WorldWideScience

Sample records for emitting planetary nebula

  1. Planetary nebulae

    International Nuclear Information System (INIS)

    Amnuehl', P.R.

    1985-01-01

    The history of planetary nebulae discovery and their origin and evolution studies is discussed in a popular way. The problem of planetary nebulae central star is considered. The connection between the white-draft star and the planetary nebulae formulation is shown. The experimental data available acknowledge the hypothesis of red giant - planetary nebula nucleus - white-draft star transition process. Masses of planetary nebulae white-draft stars and central stars are distributed practically similarly: the medium mass is close to 0.6Msub(Sun) (Msub(Sun) - is the mass of the Sun)

  2. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Kwok, S.

    1980-01-01

    A two-component dust model is suggested to explain the infrared emission from planetary nebulae. A cold dust component located in the extensive remnant of the red-giant envelope exterior to the visible nebula is responsible for the far-infrared emission. A ward dust component, which is condensed after the formation of the planetary nebula and confined within the ionized gas shell, emits most of the near- and mid-infrared radiation. The observations of NGC 7027 are shown to be consisten with such a model. The correlation of silicate emission in several planetary nebulae with an approximately +1 spectral index at low radio frequencies suggests that both the silicate and radio emissions originate from the remnant of the circumstellar envelope of th precursor star and are observable only while the planetary nebula is young. It is argued that oxygen-rich stars as well as carbon-rich stars can be progenitors of planetary nebulae

  3. Shaping of planetary nebulae

    International Nuclear Information System (INIS)

    Balick, B.

    1987-01-01

    The phases of stellar evolution and the development of planetary nebulae are examined. The relation between planetary nebulae and red giants is studied. Spherical and nonspherical cases of shaping planetaries with stellar winds are described. CCD images of nebulae are analyzed, and it is determined that the shape of planetary nebulae depends on ionization levels. Consideration is given to calculating the distances of planetaries using radio images, and molecular hydrogen envelopes which support the wind-shaping model of planetary nebulae

  4. Proto-planetary nebulae

    International Nuclear Information System (INIS)

    Zuckerman, B.

    1978-01-01

    A 'proto-planetary nebula' or a 'planetary nebula progenitor' is the term used to describe those objects that are losing mass at a rate >approximately 10 -5 Msolar masses/year (i.e. comparable to mass loss rates in planetary nebulae with ionized masses >approximately 0.2 Msolar masses) and which, it is believed, will become planetary nebulae themselves within 5 years. It is shown that most proto-planetary nebulae appear as very red objects although a few have been 'caught' near the middle of the Hertzsprung-Russell diagram. The precursors of these proto-planetaries are the general red giant population, more specifically probably Mira and semi-regular variables. (Auth.)end

  5. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1978-01-01

    The author's review concentrates on theoretical aspects of dust in planetary nebulae (PN). He considers the questions: how much dust is there is PN; what is its composition; what effects does it have on the ionization structure, on the dynamics of the nebula. (Auth.)

  6. New and misclassified planetary nebulae

    International Nuclear Information System (INIS)

    Kohoutek, L.

    1978-01-01

    Since the 'Catalogue of Galactic Planetary Nebulae' 226 new objects have been classified as planetary nebulae. They are summarized in the form of designations, names, coordinates and the references to the discovery. Further 9 new objects have been added and called 'proto-planetary nebulae', but their status is still uncertain. Only 34 objects have been included in the present list of misclassified planetary nebulae although the number of doubtful cases is much larger. (Auth.)

  7. Can planetary nebulae rotate

    International Nuclear Information System (INIS)

    Grinin, V.P.

    1982-01-01

    It is shown that the inclination of spectral lines observed in a number of planetary nebulae when the spectrograph slit is placed along the major axis, which is presently ascribed to nonuniform expansion of the shells, actually may be due to rotation of the nebulae about their minor axes, as Campbell and Moore have suggested in their reports. It is assumed that the rotation of the central star (or, if the core is a binary system, circular motions of gas along quasi-Keplerian orbits) serves as the source of the original rotation of a protoplanetary nebula. The mechanism providing for strengthening of the original rotation in the process of expansion of the shell is the tangential pressure of L/sub α/ radiation due to the anisotropic properties of the medium and radiation field. The dynamic effect produced by them is evidently greatest in the epoch when the optical depth of the nebula in the L/sub c/ continuum becomes on the order of unity in the course of its expansion

  8. Kinematics of galactic planetary nebulae

    International Nuclear Information System (INIS)

    Kiosa, M.I.; Khromov, G.S.

    1979-01-01

    The classical method of determining the components of the solar motion relative to the centroid of the system of planetary nebulae with known radial velocities is investigated. It is shown that this method is insensitive to random errors in the radial velocities and that low accuracy in determining the coordinates of the solar apex and motion results from the insufficient number of planetaries with measured radial velocities. The planetary nebulae are found not to satisfy well the law of differential galactic rotation with circular orbits. This is attributed to the elongation of their galactic orbits. A method for obtaining the statistical parallax of planetary nebulae is considered, and the parallax calculated from the tau components of their proper motion is shown to be the most reliable

  9. Red giants as precursors of planetary nebulae

    International Nuclear Information System (INIS)

    Renzini, A.

    1981-01-01

    It is generally accepted that Planetary Nebulae are produced by asymptotic giant-branch stars. Therefore, several properties of planetary nebulae are discussed in the framework of the current theory of stellar evolution. (Auth.)

  10. From red giants to planetary nebulae

    International Nuclear Information System (INIS)

    Kwok, S.

    1982-01-01

    The transition from red giants to planetary nebulae is studied by comparing the spectral characteristics of red giant envelopes and planetary nebulae. Observational and theoretical evidence both suggest that remnants of red giant envelopes may still be present in planetary nebula systems and should have significant effects on their formation. The dynamical effects of the interaction of stellar winds from central stars of planetary nebulae with the remnant red giant envelopes are evaluated and the mechanism found to be capable of producing the observed masses and momenta of planetary nebulae. The observed mass-radii relation of planetary nebulae may also be best explained by the interacting winds model. The possibility that red giant mass loss, and therefore the production of planetary nebulae, is different between Population I and II systems is also discussed

  11. Evolution of planetary nebula nuclei

    International Nuclear Information System (INIS)

    Shaw, R.A.

    1985-01-01

    The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schoenberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions. An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented

  12. Interferometric observations of planetary nebulae

    International Nuclear Information System (INIS)

    Atherton, P.D.

    1978-01-01

    Studies of the velocity field of planetary nebulae can be used to derive important information concerning their structure and dynamics. A description is given of the design, construction and operation of a servo-controlled Fabry Perot Interferometer, for the Cassegrain focus, which was built to perform these studies. New evidence is presented concerning the structure and internal motions of NGC 3242, NGC 6720 and NGC 7027. A technique is described which uses the velocity field to map variations in the electron temperature and density along the line of sight as well as across the face of the nebula. It is shown how a Fabry Perot may be used in conjunction with multi-element array detectors to facilitate this technique. Finally some extensions to the technique of capacitance micrometry are discussed which allow the operation of a single air-spaced etalon over a wide range of capacitor gaps

  13. Optical observations of southern planetary nebula candidates

    NARCIS (Netherlands)

    VandeSteene, GC; Sahu, KC; Pottasch, [No Value

    1996-01-01

    We present H alpha+[NII] images and low resolution spectra of 16 IRAS-selected, southern planetary nebula candidates previously detected in the radio continuum. The H alpha+[NII] images are presented as finding charts. Contour plots are shown for the resolved planetary nebulae. From these images

  14. Electron densities in planetary nebulae

    International Nuclear Information System (INIS)

    Stanghellini, L.; Kaler, J.B.

    1989-01-01

    Electron densities for 146 planetary nebulae have been obtained for analyzing a large sample of forbidden lines by interpolating theoretical curves obtained from solutions of the five-level atoms using up-to-date collision strengths and transition probabilities. Electron temperatures were derived from forbidden N II and/or forbidden O III lines or were estimated from the He II 4686 A line strengths. The forbidden O II densities are generally lower than those from forbidden Cl III by an average factor of 0.65. For data sets in which forbidden O II and forbidden S II were observed in common, the forbidden O II values drop to 0.84 that of the forbidden S II, implying that the outermost parts of the nebulae might have elevated densities. The forbidden Cl II and forbidden Ar IV densities show the best correlation, especially where they have been obtained from common data sets. The data give results within 30 percent of one another, assuming homogeneous nebulae. 106 refs

  15. Luminosity function for planetary nebulae and the number of planetary nebulae in local group galaxies

    International Nuclear Information System (INIS)

    Jacoby, G.H.

    1980-01-01

    Identifications of 19 and 34 faint planetary nebulae have been made in the central regions of the SMC and LMC, respectively, using on-line/off-line filter photography at [O III] and Hα. The previously known brighter planetary nebulae in these fields, eight in both the SMC and the LMC, were also identified. On the basis of the ratio of the numbers of faint to bright planetary nebulae in these fields and the numbers of bright planetary nebulae in the surrounding fields, the total numbers of planetary nebulae in the SMC and LMC are estimated to be 285 +- 78 and 996 +- 253, respectively. Corrections have been applied to account for omissions due to crowding confusion in previous surveys, spatial and detectability incompleteness, and obscuration by dust.Equatorial coordinates and finding charts are presented for all the identified planetary nebulae. The coordinates have uncertainties smaller than 0.''6 relative to nearby bright stars, thereby allowing acquisition of the planetary nebulae by bling offsetting.Monochromatic fluxes are derived photographically and used to determine the luminosity function for Magellanic Cloud planetary nebulae as faint as 6 mag below the brightest. The luminosity function is used to estimate the total numbers of planetary nebulae in eight Local Group galaxies in which only bright planetary nebulae have been identified. The dervied luminosity specific number of planetary nebulae per unit luminosity is nearly constant for all eight galaxies, having a value of 6.1 x 10 -7 planetary nebulae L -1 /sub sun/. The mass specific number, based on the three galaxies with well-determined masses, is 2.1 x 10 -7 planetary nebulae M -1 /sub sun/. With estimates for the luminosity and mass of our Galaxy, its total number of planetary nebulae is calculated to be 10,000 +- 4000, in support of the Cudworth distance scale

  16. X-ray observations of planetary nebulae

    International Nuclear Information System (INIS)

    Apparao, K.M.V.; Tarafdar, S.P.

    1990-01-01

    The Einstein satellite was used to observe 19 planetary nebulae and X-ray emission was detected from four planetary nebulae. The EXOSAT satellite observed 12 planetary nebulae and five new sources were detected. An Einstein HRI observation shows that NGC 246 is a point source, implying that the X-rays are from the central star. Most of the detected planetary nebulae are old and the X-rays are observed during the later stage of planetary nebulae/central star evolution, when the nebula has dispersed sufficiently and/or when the central star gets old and the heavy elements in the atmosphere settle down due to gravitation. However in two cases where the central star is sufficiently luminous X-rays were observed, even though they were young nebulae; the X-radiation ionizes the nebula to a degree, to allow negligible absorption in the nebula. Temperature T x is obtained using X-ray flux and optical magnitude and assuming the spectrum is blackbody. T x agrees with Zanstra temperature obtained from optical Helium lines. (author)

  17. Circumnebular neutral hydrogen in planetary nebulae

    International Nuclear Information System (INIS)

    Taylor, A.R.; Gussie, G.T.; Pottasch, S.R.

    1990-01-01

    Centimeter line observations of six compact planetary nebulae are reported. Circumnebular atomic hydrogen absorption has been observed in NGC 6790, NGC 6886, IC 418, IC 5117, and BD +30 deg 3639, while H I was not observed to a high upper limit in NGC 6741. Hydrogen was also detected in emission from BD +30 deg 3639. The expansion velocities of the circumnebular envelopes are similar to the expansion velocities observed for the ionized nebula. The optical depth of circumnebular H I appears to decrease with increasing linear radius of the ionized nebulae, indicating that these nebulae are ionization bounded and that the amount of atomic hydrogen decreases as young nebulas evolve. 28 refs

  18. Abundances in planetary nebulae : Hb 5

    NARCIS (Netherlands)

    Pottasch, S. R.; Surendiranath, R.

    The ISO spectra of the bilobal planetary nebula Hb 5 are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebula is then calculated in several ways. First by directly

  19. Galaxy dynamics with the Planetary Nebula Spectrograph

    OpenAIRE

    Napolitano, N. R.; Romanowsky, A. J.; Douglas, N. G.; Capaccioli, M.; Arnaboldi, M.; Kuijken, K.; Merrifield, M. R.; Freeman, K. C.; Gerhard, O.

    2004-01-01

    The Planetary Nebula Spectrograph is a dedicated instrument for measuring radial velocity of individual Planetary Nebulae (PNe) in galaxies. This new instrument is providing crucial data with which to probe the structure of dark halos in the outskirts of elliptical galaxies in particular, which are traditionally lacking of easy interpretable kinematical tracers at large distance from the center. Preliminary results on a sample of intermediate luminosity galaxies have shown little dark matter ...

  20. Planetary nebulae and the interstellar magnetic field

    International Nuclear Information System (INIS)

    Heiligman, G.M.

    1980-01-01

    Previous workers have found a statistical correlation between the projected directions of the interstellar magnetic field and the major axes of planetary nebulae. This result has been examined theoretically using a numerical hydromagnetic model of a cold plasma nebula expanding into a uniform vacuum magnetic field, with nebular gas accreting on the surface. It is found that magnetic pressure alone is probably not sufficient to shape most planetary nebulae to the observed degree. Phenomena are discussed which could amplify simple magnetic pressure, alter nebular morphology and account for the observed correlation. (author)

  1. Reconstruction and visualization of planetary nebulae.

    Science.gov (United States)

    Magnor, Marcus; Kindlmann, Gordon; Hansen, Charles; Duric, Neb

    2005-01-01

    From our terrestrially confined viewpoint, the actual three-dimensional shape of distant astronomical objects is, in general, very challenging to determine. For one class of astronomical objects, however, spatial structure can be recovered from conventional 2D images alone. So-called planetary nebulae (PNe) exhibit pronounced symmetry characteristics that come about due to fundamental physical processes. Making use of this symmetry constraint, we present a technique to automatically recover the axisymmetric structure of many planetary nebulae from photographs. With GPU-based volume rendering driving a nonlinear optimization, we estimate the nebula's local emission density as a function of its radial and axial coordinates and we recover the orientation of the nebula relative to Earth. The optimization refines the nebula model and its orientation by minimizing the differences between the rendered image and the original astronomical image. The resulting model allows creating realistic 3D visualizations of these nebulae, for example, for planetarium shows and other educational purposes. In addition, the recovered spatial distribution of the emissive gas can help astrophysicists gain deeper insight into the formation processes of planetary nebulae.

  2. Planetary Nebulae Beyond the Milky Way

    CERN Document Server

    Stanghellini, L; Douglas, N. G; Proceedings of the ESO Workshop held at Garching, Germany, 19-21 May, 2004

    2006-01-01

    In the last decade extra-galactic planetary nebulae (PNe) have gained increasing importance. Improved observational capabilities have allowed fainter and fainter PNe to be studied in galaxies well beyond the Milky Way. Planetary nebulae can be detected to at least 30Mpc. They are found in galaxies of all types and also between the galaxies in nearby galaxy clusters. They are valuable as probes, both for providing the velocity of their host stars and also the evolutionary status and relation to the stellar population from which they formed. This book contains the proceedings of a workshop held at ESO headquarters in Garching in 2004, the first meeting devoted entirely to Extra-galactic Planetary Nebulae. A wide range of topics is covered, from stellar and nebular astrophysics to galactic dynamics and galaxy clusters, making this volume a unique and timely reference of broad astrophysical interest.

  3. Spatiokinematical models of five planetary nebulae

    International Nuclear Information System (INIS)

    Sabbadin, F.

    1984-01-01

    The [OOOI] and Hα expansion velocity fields in the planetary nebulae NGC6058 and 6804 and the [OIII], Hα and [NII] expansion velocity fields in NGC6309, 6751 and 6818, were obtained from high dispersion spectra. Spatiokinematical models of the nebulae were derived assuming an expansion velocity of the gas proportional to the distance from the central star and using the expansion velocity-radius correlation previously given. The observational parameters of the nebulae (radius, mass and expansion velocity) and of the exciting stars (temperature, radius and luminosity) closely fit the suggested evolutionary model for this class of objects. (author)

  4. Abundance determinations in HII regions and planetary nebulae

    OpenAIRE

    Stasinska, Grazyna

    2002-01-01

    The methods of abundance determinations in HII regions and planetary nebulae are described, with emphasis on the underlying assumptions and inherent problems. Recent results on abundances in Galactic HII regions and in Galactic and extragalactic Planetary Nebulae are reviewed.

  5. ISO Spectroscopy of Proto-Planetary Nebulae

    Science.gov (United States)

    Hrivnak, Bruce J.

    2000-01-01

    features at 3.3, 6,2, 7.7, and 11.3 micron, which are commonly observed in planetary nebulae and HII regions, are also seen in these PPNs. However, their strengths relative to the continuum plateaus at 8 and 12 micron are weaker than in planetary nebulae. The 6.9 micron feature, seen almost exclusively in PPNs, is strong. The spectral energy distributions of these PPNs were fitted with a radiative-transfer model, taking into account the emission features at 21, 26, and 30 micron. A significant fraction of the total energy output is emitted in these features: as high as 20% in the 30 micron feature and 8% in the 21 micron feature. The fact that so much energy is carried in these features suggests that the material responsible for this feature must be made of abundant elements, and most likely involves carbon. The change in the in feature strengths from stronger aliphatic bonds in PPNs to stronger aromatic bonds in PNs suggests a chemical and physical evolution in the carbonaceous circumstellar dust during this transition time scale of a few thousand years.

  6. From red giants to planetary nebulae: Asymmetries, dust, and polarization

    International Nuclear Information System (INIS)

    Johnson, J.J.

    1990-01-01

    In order to investigate the development of aspherical planetary nebulae, polarimetry was obtained for a group of planetary nebulae and for objects that will evolve into planetary nebulae, i.e., red giants, late asymptotic giant branch (AGB) objects, proto-planetary nebulae, and young planetary nebulae. To study the dust around the objects in our sample, we also used data from the Infrared Astronomy Satellite (IRAS) mission. The youngest objects in our survey, red giants, had the hottest dust temperatures while planetary nebulae had the coolest. Most of the objects were intrinsically polarized, including the red giants. This indicated that the circumstellar dust shells of these objects were aspherical. Both carbon- and oxygen-rich objects could be intrinsically polarized. The intrinsic polarizations of a sample of our objects were modeled using an ellipsoidal circumstellar dust shell. The findings of this study suggest that the asphericities that lead to an aspherical planetary nebula originate when a red giant begins to undergo mass loss. The polarization and thus the asphericity as the star evolves, with both reaching a maximum during the proto-planetary nebula stage. The circumstellar dust shell will dissipate after the proto-planetary nebulae stage since no new material is being added. The polarization of planetary nebulae will thus be low. In the most evolved planetary nebulae, the dust has either been destroyed or dissipated into the interstellar medium. In these objects no polarization was observed

  7. HM Sagittae as a young planetary nebula

    International Nuclear Information System (INIS)

    Kwok, S.; Purton, C.R.

    1979-01-01

    HM Sagittae is suggested to be a very young planetary nebula recently transformed from a red-giant star through continuous mass loss. The observational data for HM Sge have been analyzed in terms of the interacting stellar wind model of planetary nebula formation. The model is in accord with virtually all the spectral data available--radio, optical, and infrared--as well as with the remarkable brightening of HM Sge observed in 1975. In particular, all three gaseous components predicted by the model are observed in the optical spectrum. The density in the newly formed shell is found to be at least 5 x 10 7 cm -3 , a value considerably higher than that found by the conventional analysis, which assumes a single-component homogeneous nebula. The radio spectrum is dominated by free-free emission from the remnant red-giant wind. The infrared spectrum suggests the presence of two dust components, one consisting of silicate grains left over from the red-giant stage and the other of grains newly formed after the 1975 brightening. The low observed shell mass is consistent with the interacting stellar wind model but is not consistent with the conventional sudden-ejection model of planetary nebula formation

  8. Evolutionary sequence of models of planetary nebulae

    International Nuclear Information System (INIS)

    Vil'koviskij, Eh.Ya.; Kondrat'eva, L.N.; Tambovtseva, L.V.

    1983-01-01

    The evolutionary sequences of model planetary nebulae of different masses have been calculated. The computed emission line intensities are compared with the observed ones by means of the parameter ''reduced size of the nebula'', Rsub(n). It is shown that the evolution tracks of Schonberner for the central stars are consistent with the observed data. Part of ionized mass Mi in any nebulae does not not exceed 0.3 b and in the average Msu(i) 3 years at actual values of radius Rsub(i) <0.025 ps. Then the luminosity growth slows down to the maximum temperature which central star reaches and decreases with sharp decrease of the star luminosity. At that, the radius of ionized zone of greater mass nebulae can even decrease, inspite of the constant expansion of the nebula. As a result nebulae of great masses having undergone the evolution can be included in the number of observed compact objects (Rsub(n) < 0.1 ps)

  9. Search for binary nuclei in planetary nebulae

    International Nuclear Information System (INIS)

    Jasniewicz, G.

    1987-01-01

    Two planetary nebulae with central stars of late spectral type were observed: LT 5 and Abell 35. The variation of the systemic velocity of the G-binary in HD 112313 gives strong support to the idea of a third body in the nucleus of LT 5. In addition, it is concluded that observed photometric variations of BD -22 deg 3467 (the central star of Abell 35) can best be explained by the binary nature of the star. 9 references

  10. Search for binary nuclei in planetary nebulae

    Science.gov (United States)

    Jasniewicz, G.

    Two planetary nebulae with central stars of late spectral type were observed: LT 5 and Abell 35. The variation of the systemic velocity of the G-binary in HD 112313 gives strong support to the idea of a third body in the nucleus of LT 5. In addition, it is concluded that observed photometric variations of BD -22 deg 3467 (the central star of Abell 35) can best be explained by the binary nature of the star.

  11. N III line emission in planetary nebulae - Not Bowen fluorescence

    Science.gov (United States)

    Kastner, S. O.; Bhatia, A. K.

    1991-01-01

    A direct comparison of photometrically observed line ratios in the N III 4640 and 4100 A multiplets emitted by planetary nebulae with theoretically predicted ratios expected from the postulated Bowen process of selective photoexcitation by an O III resonance line shows that the N III lines are not produced by the Bowen process as has been commonly accepted. This will have consequences for the interpretation of these lines in other astrophysical sources. A further, unexpected result is that the N III level populations involved are found to be essentially in statistical equilibrium. Possible populating mechanisms are briefly discussed.

  12. Influence of stellar duplicity on the form of planetary nebulae

    International Nuclear Information System (INIS)

    Kolesnik, I.G.; Pilyugin, L.S.

    1986-01-01

    Formation of planetary nebulae's spatial structures is considered. Simple expression for angular distribution of density in planetary nebulae is obtained. Bipolar structures are formed effectively in binary systems in which the velocity of the expanding shell around the main star is smaller than the orbital velocity of the satellite. Masses of satellites lie in the range 0.1-0.4Msub(sun). Theoretical isophotal contour map for the model of the planetary nebula NGC 3587 is consistent with observational data. It is shown that central stars of planetary nebulae are usually binary systems

  13. The current research of planetary nebulae distance measurement

    Science.gov (United States)

    Yang, Yuan-yuan; Zhu, Hui; Tian, Wen-wu; Wu, Dan

    2015-08-01

    Planetary Nebula is an important tracer of Galactic chemical history and evolution, star and interstellar evolution. Distance as a basic physical parameter of planetary nebula, is crucial to study its size, luminosity, ionized mass, formation rate, space density and Galactic distribution. Distance of planetary nebula has been studied for several decades, but most of their distances are not well determined, e.g. only thirty-one planetary nebulae have distance measurement with uncertainty within 20%. We summarize major distance measurement methods of planetary nebulae, i.e., trigonometric parallax, cluster member, expansion parallax, spectroscopic parallax, reddening, Na D absorption, determinations of central star gravities, Shklovsky method, kinematics method, and then discuss the limitations and applications scope of each method in detail. Actually, applying different methods to the same planetary nebulae can have a huge difference in distance, and even the same method can lead to great difference for the same planetary nebula. We focus on the kinematics method applied to planetary nebulae either seriously effected by Galactic extinction or having no observable centra star but being radio bright. The kinematics distance has been used in our on-going project of radio planetary nebulae distance measurement.

  14. of Planetary Nebulae III. NGC 6781

    Directory of Open Access Journals (Sweden)

    Hugo E. Schwarz

    2006-01-01

    Full Text Available Continuing our series of papers on the three-dimensional (3D structures and accurate distances to Planetary Nebulae (PNe, we present our study of the planetary nebula NGC6781. For this object we construct a 3D photoionization model and, using the constraints provided by observational data from the literature we determine the detailed 3D structure of the nebula, the physical parameters of the ionizing source and the first precise distance. The procedure consists in simultaneously fitting all the observed emission line morphologies, integrated intensities and the two-dimensional (2D density map from the [SII] (sulfur II line ratios to the parameters generated by the model, and in an iterative way obtain the best fit for the central star parameters and the distance to NGC6781, obtaining values of 950±143 pc (parsec – astronomic distance unit and 385 LΘ (solar luminosity for the distance and luminosity of the central star respectively. Using theoretical evolutionary tracks of intermediate and low mass stars, we derive the mass of the central star of NGC6781 and its progenitor to be 0.60±0.03MΘ (solar mass and 1.5±0.5MΘ respectively.

  15. Planetary nebulae and the interstellar medium

    Science.gov (United States)

    Aller, L. H.

    1986-01-01

    In addition to available published data on planetary nebulae (PN), some 40 objects largely concentrated towards the galactic center and anticenter regions were included. All were observed with the Lick 3(sup m) telescope and image tube scanner. Abundances of C, N, O, Ne, Cl, and Ar were determined by a procedure in which theoretical models were used to obtain ionization correction factors (ICF). Of the 106 PN, 66 are N-rich and 40 are N-poor. There appear to be no significant differences between the average compositions in the solar neighborhood and the average taken over the entire observable portion of the galaxy.

  16. The Planetary Nebula Spectrograph : The green light for galaxy kinematics

    NARCIS (Netherlands)

    Douglas, NG; Arnaboldi, M; Freeman, KC; Kuijken, K; Merrifield, MR; Romanowsky, AJ; Taylor, K; Capaccioli, M; Axelrod, T; Gilmozzi, R; Hart, J; Bloxham, G; Jones, D

    2002-01-01

    Planetary nebulae (PNe) are now well established as probes of galaxy dynamics and as standard candles in distance determinations. Motivated by the need to improve the efficiency of planetary nebulae searches and the speed with which their radial velocities are determined, a dedicated instrument-the

  17. IRAS-22568+6141 - A NEW BIPOLAR PLANETARY-NEBULA

    NARCIS (Netherlands)

    LARIO, PG; MANCHADO, A; RIERA, A; MAMPASO, A; POTTASCH, [No Value

    When carrying out a survey of IRAS sources with infrared colours similar to those of planetary nebulae, IRAS 22568 + 6141 was found to be a new young planetary nebula. It shows an extension of 8" and a bipolar structure. From its optical low resolution spectrum we have derived a high extinction

  18. Optical observations of planetary nebula candidates from the northern hemisphere

    NARCIS (Netherlands)

    VandeSteene, GC; Jacoby, GH; Pottasch, [No Value

    We present H alpha+[N II] images of 17 and low resolution spectra of 14 IRAS-selected planetary nebula candidates. The H alpha+[N II] images are presented as finding charts. Contour plots are shown for the resolved planetary nebulae. From these images accurate optical positions and mean optical

  19. Morpho-kinematic modeling of planetary nebulae

    Science.gov (United States)

    Chan, Tsz-Pan (Henry)

    2009-11-01

    The Planetary Nebulae (PNe) are the transition phase between asymptotic giant branch (AGB) star and white dwarfs for stars with masses between 1 and 8 M⊙. They were originally thought to be well-studied and can be explained with simple models. With the advance of imaging technology especially on Space Telescope (HST), the shapes of PNe have been found to be much more complex than we assumed to be. We aimed to investigate on the basic but mysterious intrinsic three-dimensional structures using the newly developed modeling software. Astronomers usually use the morphological classification on group and classify different properties of PNe. Over the past century many attempts have been made for this classification to seek for explaining and understanding the threedimensional structure that is responsible for the observed images. There have been two beliefs in explaining the variety of shapes of PNe and among them the most amazing one is that the morphologies can be accounted by different orientations of a single structure (Khromov & Kohoutek, 1968). Motivated by the study of Ring Nebula on its intrinsic structure, we investigated the possibility that different types of morphology in PNe can be explained by a single model. We used the newly developed modeling code SHAPE (Steffen et al., 2006), which cooperates the use of spatial information as well as its kinematics, and aimed to quantitatively investigate the basic structure inside PNe. We investigated two classical nebulae: NGC 2346 and NGC 2440. We proposed a simple but adequate model for these nebulae. Stimulated optical images and the p-v arrays were derived by the modeling code SHAPE to make comparison with the observed data to seek for the correctness of the model. Hubble velocity field and inverse square law density distribution were assumed throughout the modeling process. This model provides insights in seeking further adequate intrinsic structure of PNe.

  20. The Making of a Pre-Planetary Nebula

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    The gas expelled by dying stars gets twisted into intricate shapes and patterns as nebulae form. Now a team of researchers might have some answers about how this happens.Whats a Pre-Planetary Nebula?This H-R diagram for the globular cluster M5 shows where AGB stars lie: they are represented by blue markers here. The AGB is one of the final stages in a low- to intermediate-mass stars lifetime. [Lithopsian]When a low- to intermediate-mass star approaches the end of its lifetime, it moves onto the Asymptotic Giant Branch (AGB) in the Herzsprung-Russell diagram. As the star exhausts its fuel here, it shrugs off its outer layers. These layers of gas then encase the stars core, which is not yet hot enough to ionize the gas and cause it to glow.Instead, during this time the gas is relatively cool and dark, faintly reflecting light from the star and emitting only very dim infrared emission of its own. At this stage, the gas represents a pre-planetary nebula. Only later when the stellar core contracts enough to heat up and emit ionizing radiation does the nebula begin to properly glow, at which point it qualifies as a full planetary nebula.Images of OH231 in optical light (top) and 12CO (bottom) taken from the literature. [See Balick et al. 2017 for full credit]Unexpected ShapesPre-planetary nebulae are a very short-lived evolutionary stage, so weve observed only a few hundred of them which has left many unanswered questions about these objects.One particular mystery is that of their shapes: if these nebulae are formed by stars expelling their outer layers, we would naively expect them to be simple spherical shells and yet we observe pre-planetary nebulae to have intricate shapes and patterns. How does the star create these asymmetric shapes? A team of scientists led by Bruce Balick (University of Washington, Seattle) has now used simulations to address this question.Injecting MassBalick and collaborators use 3D hydrodynamic simulations to model one particular pre-planetary

  1. Photoionization modelling of planetary nebulae - II. Galactic bulge nebulae, a comparison with literature results

    NARCIS (Netherlands)

    van Hoof, PAM; Van de Steene, GC

    1999-01-01

    We have constructed photoionization models of five galactic bulge planetary nebulae using our automatic method, which enables a fully self-consistent determination of the physical parameters of a planetary nebula. The models are constrained using the spectrum, the IRAS and radio fluxes and the

  2. Planetary nebulae with UVIT: Far ultra-violet halo around the Bow Tie nebula (NGC 40)

    Science.gov (United States)

    Kameswara Rao, N.; Sutaria, F.; Murthy, J.; Krishna, S.; Mohan, R.; Ray, A.

    2018-01-01

    Context. NGC 40 is a planetary nebula with diffuse X-ray emission, suggesting an interaction of the high-speed wind from WC8 central star (CS) with the nebula. It shows strong C IV 1550 Å emission that cannot be explained by thermal processes alone. We present here the first map of this nebula in C IV emission using broad band filters on the Ultra-Violet Imaging Telescope (UVIT). Aim. We aim to map the hot C IV-emitting gas and its correspondence with soft X-ray (0.3-8 keV) emitting regions in order to study the shock interaction between the nebula and the ISM. We also aim to illustrate the potential of UVIT for nebular studies. Methods: We carry out a morphological study of images of the nebula obtained at an angular resolution of about 1.3″ in four UVIT filter bands that include C IV 1550 Å and [C II] 2326 Å lines as well as UV continuum. We also make comparisons with X-ray, optical, and IR images from the literature. Results: The [C II] 2326 Å images show the core of the nebula with two lobes on either side of CS similar to [N II]. The C IV emission in the core shows similar morphology and extent to that of diffuse X-ray emission concentrated in nebular condensations. A surprising UVIT discovery is the presence of a large faint far UV (FUV) halo in an FUV filter with λeff of 1608 Å. The UV halo is not present in any other UV filter. The FUV halo is most likely due to UV fluorescence emission from the Lyman bands of H2 molecules. Unlike the optical and IR halo, the FUV halo trails predominantly towards the south-east side of the nebular core, opposite to the CS's proper motion direction. Conclusions: Morphological similarity of C IV 1550 Å and X-ray emission in the core suggests that it results mostly from the interaction of strong CS wind with the nebula. The FUV halo in NGC 40 highlights the extensive existence of H2 molecules in the regions even beyond the optical and IR halos. Thus UV studies are important to estimate the amount of H2, which is

  3. Young planetary nebula with OH molecules - NGC 6302

    International Nuclear Information System (INIS)

    Payne, H.E.; Phillips, J.A.; Terzian, Y.

    1988-01-01

    The results of a sensitive survey of planetary nebulae in all four ground-state OH lines are reported. The results confirm that evolved planetary nebulas are not OH sources in general. However, one interesting object was not detected: an OH 1612 MHz maser in the young planetary nebula NGC 6302. This nebula may be in a brief evolutionary stage, similar to the young and compact planetary nebula Vy 2-2, where OH has already been detected. In addition, the results of further observations of NGC 6302 are reported, including VLA observations of the 1612 MHz line and continuum emission and detections of rotationally excited OH lines at 5-cm wavelength in absorption. 28 references

  4. Relation between radius and expansion velocity in planetary nebulae

    International Nuclear Information System (INIS)

    Chu, Y.H.; Kwitter, K.B.; Kaler, J.B.

    1984-01-01

    The expansion velocity-radius (R-V) relation for planetary nebulae is examined using the existing measurements of expansion velocities and recent calculations of radii. It is found that some of the previously alleged R-V relations for PN are not convincingly established. The scatter in the R-V plots may be due largely to stratification of ions in individual nebulae and to heterogeneity in the planetary nebula population. In addition, from new echelle/CCD observations of planetary nebulae, it is found that spatial information is essential in deriving the internal kinematic properties. Future investigations of R-V relations should be pursued separately for groups of planetaries with similar physical properties, and they should employ observations of appropriate low excitation lines in order to measure the expansion velocity at the surface of the nebula. 26 references

  5. Properties of dust grains in planetary nebulae. I. The ionized region of NGC 6445

    NARCIS (Netherlands)

    van Hoof, PAM; Van de Steene, GC; Beintema, DA; Martin, PG; Pottasch, [No Value

    2000-01-01

    One of the factors influencing the spectral evolution of a planetary nebula is the fate of the dust grains that are emitting the infrared continuum. Several processes have been proposed that either destroy the grains or remove them from the ionized region. To test whether these processes are

  6. Shape, structure, and morphology in planetary nebulae

    Science.gov (United States)

    Shaw, Richard A.

    2012-08-01

    A revival over the past two decades in planetary nebula (PN) morphological studies springs from a combination of factors, including the advent of wide-area, high dynamic range detectors; the growing archives of high resolution images from the X-ray to the sub-mm; and the advent of sophisticated models of the co-evolution of PNe and their central stars. Yet the story of PN formation from their immediate precursors, the AGB stars, is not yet fully written. PN morphology continues to inspire, provide context for physical interpretation, and serve as an ultimate standard of comparison for many investigations in this area of astrophysics. After a brief review of the remarkable successes of PN morphology, I summarize how this tool has been employed over the last half-decade to advance our understanding of PNe.

  7. Estimating the Binary Fraction of Central Stars of Planetary Nebulae

    Science.gov (United States)

    Douchin, Dimitri

    2015-01-01

    Planetary nebulae are the end-products of intermediate-mass stars evolution, following a phase of expansion of their atmospheres at the end of their lives. Observationally, it has been estimated that 80% of them have non-spherical shapes. Such a high fraction is puzzling and has occupied the planetary nebula community for more than 30 years. One scenario that would allow to justify the observed shapes is that a comparable fraction of the progenitors of central stars of planetary nebula (CSPN) are not single, but possess a companion. The shape of the nebulae would then be the result of an interaction with this companion. The high fraction of non-spherical planetary nebulae would thus imply a high fraction of binary central stars of planetary nebulae, making binarity a preferred channel for planetary nebula formation. After presenting the current state of knowledge regarding planetary nebula formation and shaping and reviewing the diverse efforts to find binaries in planetary nebulae, I present my work to detect a near-infrared excess that would be the signature of the presence of cool companions. The first part of the project consists in the analysis of data and photometry acquired and conducted by myself. The second part details an attempt to make use of archived datasets: the Sloan Digital Sky Survey Data Release 7 optical survey and the extended database assembled by Frew (2008). I also present results from a radial velocity analysis of VLT/UVES spectra for 14 objects aiming to the detection of spectroscopic companions. Finally I give details of the analysis of optical photometry data from our observations associated to the detection of companions around central stars of planetary nebulae using the photometric variability technique. The main result of this thesis is from the near-infrared excess studies which I combine with previously published data. I conclude that if the detected red and NIR flux excess is indicative of a stellar companion then the binary

  8. Galactic planetary nebulae and evolution of their nuclei

    International Nuclear Information System (INIS)

    Khromov, G.S.

    1980-01-01

    The galactic system of planetary nebulae is investigated using previously constructed distance scale and kinematics data. A strong effect of observational selection is established, which has the consequence that with increasing distance, ever brighter and younger objects are observed. More accurate determinations of the spatial and surface densities of the planetary nebulae system are obtained as well as a new estimate of their total number in the Galaxy, which is approximately 200,000. New estimates are also made of the masses of the nebulae, the absolute magnitudes of the nebulae and their nuclei, and other physical parameters of these objects. The spatial and kinematic characteristics of the planetary nebulae indicate that they are objects of the old type I population. It is possible that their remote ancestors are main sequence stars of the type B8-A5-F or as yet unidentified objects of the same galactic subsystem

  9. On planetary nebulae as sources of carbon dust: Infrared emission from planetary nebulae of the galactic halo

    International Nuclear Information System (INIS)

    Dinerstein, H.L.; Lester, D.F.

    1990-01-01

    Researchers examine here the characteristics of the infrared emission from the four planetary nebulae which are believed on the basis of their low overall metallicities to belong to the halo population. These nebulae are of particular interest because they are the most metal-poor ionized nebulae known in our Galaxy, and offer the opportunity to probe possible dependences of the dust properties on nebular composition. Researchers present fluxes extracted from co-addition of the IRAS data, as well as ground-based near infrared measurements. Each of the four halo objects, including the planetary nebula in the globular cluster M15, is detected in at least one infrared band. Researchers compare the estimated infrared excesses of these nebulae (IRE, the ratio of measured infrared power to the power available in the form of resonantly-trapped Lyman alpha photons) to those of disk planetary nebulae with similar densities but more normal abundances. Three of the halo planetaries have IRE values similar to those of the disk nebulae, despite the fact that their Fe- and Si-peak gas phase abundances are factors of 10 to 100 lower. However, these halo nebulae have normal or elevated C/H ratios, due to nuclear processing and mixing in their red giant progenitors. Unlike the other halo planetaries, DDDM1 is deficient in carbon as well as in the other light metals. This nebula has a substantially lower IRE than the other halo planetaries, and may be truly dust efficient. Researchers suggest that the deficiency is due to a lack of the raw material for producing carbon-based grains, and that the main bulk constituent of the dust in these planetary nebulae is carbon

  10. Chemical composition of planetary nebulae : Including ISO results

    NARCIS (Netherlands)

    Pottasch, [No Value; Beintema, DA; Salas, JB; Feibelman, WA; Henney, WJ; Franco, J; Martos, M; Pena, M

    2002-01-01

    The method of determining abundances using Infrared Space Observatory spectra is discussed. The results for seven planetary nebula are given. Using these data, a preliminary discussion of their evolution is given.

  11. Distinguishing between symbiotic stars and planetary nebulae

    Science.gov (United States)

    Iłkiewicz, K.; Mikołajewska, J.

    2017-10-01

    Context. The number of known symbiotic stars (SySt) is still significantly lower than their predicted population. One of the main problems in finding the total population of SySt is the fact that their spectrum can be confused with other objects, such as planetary nebulae (PNe) or dense H II regions. This problem is reinforced by the fact that in a significant fraction of established SySt the emission lines used to distinguish them from other objects are not present. Aims: We aim at finding new diagnostic diagrams that could help separate SySt from PNe. Additionally, we examine a known sample of extragalactic PNe for candidate SySt. Methods: We employed emission line fluxes of known SySt and PNe from the literature. Results: We found that among the forbidden lines in the optical region of spectrum, only the [O III] and [N II] lines can be used as a tool for distinguishing between SySt and PNe, which is consistent with the fact that they have the highest critical densities. The most useful diagnostic that we propose is based on He I lines, which are more common and stronger in SySt than forbidden lines. All these useful diagnostic diagrams are electron density indicators that better distinguish PNe and ionized symbiotic nebulae. Moreover, we found six new candidate SySt in the Large Magellanic Cloud and one in M 81. If confirmed, the candidate in M 81 would be the farthest known SySt thus far.

  12. Classification of ISO SWS 01 spectra of proto-planetary nebulae: a search for precursors of planetary nebulae with [WR] central stars

    OpenAIRE

    Szczerba, R.; Stasi{ń}ska, G.; Siódmiak, N.; Górny, S. K.

    2002-01-01

    We have analyzed ISO SWS 01 observations for 61 proto-planetary nebulae candidates and classified their spectra according to their dominant chemistry. On the basis of our classification and the more general classification of SWS 01 spectra by Kraemer et al. (2002) we discuss the connection between proto-planetary nebulae candidates and planetary nebulae, with emphasis on possible precursors of planetary nebulae with [WR] central stars.

  13. IDENTIFICATION OF AN OLD PLANETARY-NEBULA AROUND THE PG-1159 STAR - PG-1520+525

    NARCIS (Netherlands)

    JACOBY, GH; VANDESTEENE, G

    We have surveyed two PG 1159 class stars for the presence of ancient planetary nebulae by direct Her imaging. While we easily found an 11' diameter nebula around PG 1520+525, no nebula was detected around PG 1424+535. This nebula is the tenth member of the class of planetary nebulae surrounding PG

  14. Accounting for planet-shaped planetary nebulae

    Science.gov (United States)

    Sabach, Efrat; Soker, Noam

    2018-01-01

    By following the evolution of several observed exoplanetary systems, we show that by lowering the mass-loss rate of single solar-like stars during their two giant branches, these stars will swallow their planets at the tip of their asymptotic giant branch (AGB) phase. This will most likely lead the stars to form elliptical planetary nebulae (PNe). Under the traditional mass-loss rate these stars will hardly form observable PNe. Stars with a lower mass-loss rate as we propose, about 15 per cent of the traditional mass-loss rate of single stars, leave the AGB with much higher luminosities than what traditional evolution produces. Hence, the assumed lower mass-loss rate might also account for the presence of bright PNe in old stellar populations. We present the evolution of four exoplanetary systems that represent stellar masses in the range of 0.9-1.3 M⊙. The justification for this low mass-loss rate is our assumption that the stellar samples that were used to derive the traditional average single-star mass-loss rate were contaminated by stars that suffer binary interaction.

  15. Abundances in Eight M31 Planetary Nebulae

    Science.gov (United States)

    Hensley, Kerry G.; Kwitter, Karen B.; Corradi, Romano; Galera-Rosillo, R.; Balick, Bruce; Henry, Richard B. C.

    2014-06-01

    As part of a continuing project using planetary nebulae (PNe) to study the chemical evolution and formation history of M31 (see accompanying poster by Balick et al.), we obtained spectra of eight PNe in the fall of 2013 with the OSIRIS spectrograph on the GTC. All of these PNe are located outside M31’s inner disk and bulge. Spectral coverage extended from 3700-7800Å with a resolution of ~6 Å. Especially important in abundance determinations is the detection of the weak, temperature-sensitive auroral line of [O III], at 4363Å, which is often contaminated by Hg I 4358Å from streetlights; the remoteness of the GTC eliminated this difficulty. We reduced and measured the spectra using IRAF, and derived nebular diagnostics and abundances with ELSA, our in-house five-level-atom program. Here we report the chemical abundances determined from these spectra. The bottom line is that the oxygen abundances in these PNe are all within a factor of 2-3 of the solar value, (as are all the other M31 PNe our team has previously measured) despite the significant range of galactocentric distance. Future work will use these abundances to constrain models of the central star to estimate progenitor masses and ages. In particular we will use the results to investigate the hypothesis that these PNe might represent a population related to the encounter between M31 and M33 ~3 Gy ago. We gratefully acknowledge support from Williams College.

  16. Statistical and physical study of one-sided planetary nebulae.

    Science.gov (United States)

    Ali, A.; El-Nawawy, M. S.; Pfleiderer, J.

    The authors have investigated the spatial orientation of one-sided planetary nebulae. Most of them if not all are interacting with the interstellar medium. Seventy percent of the nebulae in the sample have inclination angles larger than 45° to the Galactic plane and 30% of the inclination angles are less than 45°. Most of the selected objects are old, evolved planetary nebulae with large dimensions, and not far away from the Galactic plane. Seventy-five percent of the objects are within 160 pc from the Galactic plane. The enhanced concavity arc can be explained physically as a result of the 'planetary nebulae-interstellar matter' interaction. The authors discuss the possible effect of the interstellar magnetic field in the concavity regions.

  17. On the evolution of central stars of planetary nebulae

    International Nuclear Information System (INIS)

    Yahel, R.Z.

    1977-01-01

    The evolution of nuclei of planetary nebulae has been calculated from the end of the ejection stage that produces the nebulae to the white dwarf stage. The structure of the central star is in agreement with the general picture of Finzi (1973) about the mass ejection from the progenitors of planetary nebulae. It has been found that in order to obtain evolutionary track consistent with the Harman-Seaton track (O'Dell, 1968) one has to assume that the masses of the nuclei stars are less than approximately 0.7 solar masses. The calculated evolutionary time scale of the central stars of planetary nebulae is approximately 2 x 10 4 yr. This time scale is negatively correlated with the stellar mass: the heavier the stellar mass, the shorter the evolutionary time scale. (Auth.)

  18. From red giant to planetary nebula - Dust, asymmetry, and polarization

    International Nuclear Information System (INIS)

    Johnson, J.J.; Jones, T.J.

    1991-01-01

    The polarization characteristics of stars in the stages of evolution from red giant to planetary nebula are investigated. Polarization is found to be a characteristic of the majority of these stars. The maximum observed polarization increases with age as the star evolves up the asymptotic giant branch (AGB) to the protoplanetary nebula phase, where the polarization reaches a maximum. The polarization then decreases as the star further evolves into a planetary nebula. These results indicate that aspherical mass loss is likely to be a continual feature of the late stages of stellar evolution, maintaining a clear continuity throughout the life of a star from the moment it first develops a measurable dust shell. The aspherical morphology seen in planetary nebulae has its origin in an intrinsic property of the star that is present at least as early as its arrival at the base of the AGB. 77 refs

  19. A radio search for planetary nebulae near the galactic center

    International Nuclear Information System (INIS)

    Isaacman, R.B.

    1980-01-01

    Because of galactic center is a hostile environment, and because planetaries are weak radio emitters, it is not clear a priori that one expects to detect any planetary nebulae at all in the nuclear region of the Galaxy. Therefore the expected lifetime and flux density distribution of galactic center nebulae is considered. The principal observational results from the Westerbork data, and the results of some pilot observations with the Very Large Array, which were intended to distinguish planetaries from other radio sources on an individual basis are given. (Auth.)

  20. Theoretical investigation into the existence of molecules in planetary nebulae

    International Nuclear Information System (INIS)

    Carlson, W.J.

    1980-01-01

    Calculations of chemical kinetic equilibrium molecular abundances in the neutral regions of planetary nebulae are presented. The development of these abundances during the expansion of the nebula is calculated. The physical parameters in the neutral regions following the formation of the nebula by the ejection of the envelope of a long peiod variable star have been taken from available dynamical models. Similarly, the temperature and luminosity of the central star as a function of time have been taken from available theoretical calculations. The thermal equilibrium has been solved independently. The temperatures in the shell and later in the condensations which develop are in the range from 30 to 250 K. Number densities range from 10 7 for the youngest model calculated to 2 x 10 4 for neutral condensations in a 10,000 year old nebula. It is shown that, for a typical nebula containing 0.2 Msub solar, molecules are expected to be the dominant form for only a short period early in the expansion phase. Subsequently, the condensations are not sufficiently optically thick to permit the continued existence of a preponderance of molecules. The molecular abundances in the later models are similar to those in diffuse interstellar clouds. The expectation arising from those results is that little molecular material will be injected into the interstellar medium by planetary nebulae. There is, however, a remarkable resemblance between the conditions in the model calculated at very early stages of the expansion and conditions deduced from observations for proto-planetary nebulae

  1. Ultraviolet spectroscopy of planetary nebulae in the Magellanic Clouds

    International Nuclear Information System (INIS)

    Maran, S.P.; Aller, L.H.; Gull, T.R.; Stecher, T.P.

    1982-01-01

    Ultraviolet spectra of three high excitation planetary nebulae in the Magellanic Clouds (LMC P40, SMC N2, SMC N5) were obtained with the International Ultraviolet Explorer. The results are analyzed together with new visual wavelength spectrophotometry of LMC P40 and published data on SMC N2 and SMC N5 to investigate chemical composition and in particular to make the first reliable estimates of the carbon abundance in extragalactic planetary nebulae. Although carbon is at most only slightly less abundant in the LMC and SMC planetary nebulae than in galactic planetaries, it is almost 40 times more abundant in the SMC planetaries than in the SMC interstellar medium, and is about 6 times more abundant in the LMC planetary than in the LMC interstellar medium. According to our limited sample, the net result of carbon synthesis and convective dredgeup in the progenitors of planetary nebulae, as reflected in the nebular carbon abundance, is roughly the same in the Galaxy, the LMC, and the SMC

  2. Asymmetric Planetary Nebulae VI: the conference summary

    Science.gov (United States)

    De Marco, O.

    2014-04-01

    The Asymmetric Planetary Nebulae conference series, now in its sixth edition, aims to resolve the shaping mechanism of PN. Eighty percent of PN have non spherical shapes and during this conference the last nails in the coffin of single stars models for non spherical PN have been put. Binary theories abound but observational tests are lagging. The highlight of APN6 has been the arrival of ALMA which allowed us to measure magnetic fields on AGB stars systematically. AGB star halos, with their spiral patterns are now connected to PPN and PN halos. New models give us hope that binary parameters may be decoded from these images. In the post-AGB and pre-PN evolutionary phase the naked post-AGB stars present us with an increasingly curious puzzle as complexity is added to the phenomenologies of objects in transition between the AGB and the central star regimes. Binary central stars continue to be detected, including the first detection of longer period binaries, however a binary fraction is still at large. Hydro models of binary interactions still fail to give us results, if we make an exception for the wider types of binary interactions. More promise is shown by analytical considerations and models driven by simpler, 1D simulations such as those carried out with the code MESA. Large community efforts have given us more homogeneous datasets which will yield results for years to come. Examples are the ChanPlaN and HerPlaNe collaborations that have been working with the Chandra and Herschel space telescopes, respectively. Finally, the new kid in town is the intermediate-luminosity optical transient, a new class of events that may have contributed to forming several peculiar PN and pre-PN.

  3. Ultraviolet imaging of planetary nebulae with GALEX

    Science.gov (United States)

    Bianchi, Luciana; Thilker, David

    2018-05-01

    Over four hundred Galactic Planetary Nebulae (PNe) have been imaged by GALEX in two ultraviolet (UV) bands, far-UV (FUV, 1344-1786 Å, λ _{eff}= 1528 Å) and near-NUV (NUV, 1771-2831 Å, λ _{eff} = 2271 Å). We present examples of extended PNe, for which UV spectroscopy is also available, to illustrate the variety in UV morphology and color, which reflects ionization conditions. The depth of the GALEX imaging varies from flux ≈ 0.4/5× 10 ^{-18} ergs cm^{-2} s^{-1} Å^{-1} \\square ^'' -1} (FUV/NUV) for exposures of the order of ˜ 100 seconds, typical of the survey with the largest area coverage, to ˜ 0.3/8.3× 10^{-19} ergs cm^{-2} s^{-1} Å^{-1} \\square ^'' -1} (FUV/NUV) for ˜ 1500 sec exposures, typical of the second largest survey (see Bianchi in Astrophys. Space Sci. 320:11, 2009; Bianchi et al. in Adv. Space Res. 53:900, 2014). GALEX broad-band FUV and NUV fluxes include nebular emission lines and in some cases nebular continuum emission. The sensitivity of the GALEX instrument and the low sky background, especially in FUV, enable detection and mapping of very faint ionization regions and fronts, including outermost wisps and bow shocks. The FUV-NUV color of the central star provides a good indication of its T_{eff}, because the GALEX FUV-NUV color is almost reddening-free for Milky Way type dust (Bianchi et al. in Astrophys. J. Suppl. Ser. 230:24, 2017; Bianchi in Astrophys. Space Sci. 335:51, 2011, Bianchi in Astrophys. Space Sci. 354:103, 2014) and it is more sensitive to hot temperatures than optical colors.

  4. Abundances of planetary nebula NGC 5315

    NARCIS (Netherlands)

    Pottasch, [No Value; Beintema, DA; Salas, JB; Koornneef, J; Feibelman, WA

    2002-01-01

    The ISO and IUE spectra of the elliptical nebula NGC 5315 is presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous

  5. Expansion patterns and parallaxes for planetary nebulae

    Science.gov (United States)

    Schönberner, D.; Balick, B.; Jacob, R.

    2018-02-01

    Aims: We aim to determine individual distances to a small number of rather round, quite regularly shaped planetary nebulae by combining their angular expansion in the plane of the sky with a spectroscopically measured expansion along the line of sight. Methods: We combined up to three epochs of Hubble Space Telescope imaging data and determined the angular proper motions of rim and shell edges and of other features. These results are combined with measured expansion speeds to determine individual distances by assuming that line of sight and sky-plane expansions are equal. We employed 1D radiation-hydrodynamics simulations of nebular evolution to correct for the difference between the spectroscopically measured expansion velocities of rim and shell and of their respective shock fronts. Results: Rim and shell are two independently expanding entities, driven by different physical mechanisms, although their model-based expansion timescales are quite similar. We derive good individual distances for 15 objects, and the main results are as follows: (i) distances derived from rim and shell agree well; (ii) comparison with the statistical distances in the literature gives reasonable agreement; (iii) our distances disagree with those derived by spectroscopic methods; (iv) central-star "plateau" luminosities range from about 2000 L⊙ to well below 10 000 L⊙, with a mean value at about 5000 L⊙, in excellent agreement with other samples of known distance (Galactic bulge, Magellanic Clouds, and K648 in the globular cluster M 15); (v) the central-star mass range is rather restricted: from about 0.53 to about 0.56 M⊙, with a mean value of 0.55 M⊙. Conclusions: The expansion measurements of nebular rim and shell edges confirm the predictions of radiation-hydrodynamics simulations and offer a reliable method for the evaluation of distances to suited objects. Results of this paper are based on observations made with the NASA/ESA Hubble Space Telescope in Cycle 16 (GO11122

  6. Modern techniques in galaxy kinematics : Results from planetary nebula spectroscopy

    NARCIS (Netherlands)

    Romanowsky, AJ; Douglas, NG; Kuijken, K; Arnaboldi, M; Gerssen, J; Merrifield, MR; Kwok, S; Dopita, M; Sutherland, R

    2003-01-01

    We have observed planetary nebulae (PNe) in several early-type galaxies using new techniques on 4- to 8-meter-class telescopes. We obtain the first large data sets (greater than or similar to 100 velocities each) of PN kinematics in galaxies at greater than or similar to 15 Mpc, and present some

  7. Physical conditions in Photo-Dissociation Regions around Planetary Nebulae

    NARCIS (Netherlands)

    Bernard-Salas, J; Tielens, A. G. G. M.

    We present observations of the infrared fine-structure lines of [Si II] (34.8 mum), [O I] (63.2 and 145.5 mum) and [C II] (157.7 mum) obtained with the ISO SWS and LWS spectrographs of nine Planetary Nebulae (PNe). These lines originate in the Photo-Dissociation Regions (PDRs) associated with the

  8. ON AN ALTERNATIVE STATISTICAL DISTANCE SCALE FOR PLANETARY-NEBULAE

    NARCIS (Netherlands)

    VANDESTEENE, GC; ZIJLSTRA, AA

    We propose to use the correlation between the distance-independent radio continuum brightness temperature and the distance-dependent radius to determine statistical distances to planetary nebulae. This correlation satisfies two objective criteria which define a statistical distance scale: (1) We

  9. The ISO-SWS spectrum of planetary nebula NGC 7027

    NARCIS (Netherlands)

    Salas, JB; Pottasch, [No Value; Beintema, DA; Wesselius, PR

    We present the infrared spectrum of the planetary nebula NGC7027 observed with the Short Wavelength Spectrometer (SWS), on board the Infrared Space Observatory (ISO). These data allow us to derive the electron density and, together with the IUE and optical spectra, the electron temperature for

  10. The central star of the Planetary Nebula NGC 6537

    NARCIS (Netherlands)

    Pottasch, [No Value

    2000-01-01

    The fact that Space Telescope WFPC2 images of the planetary nebula NGC 6537 fail to show the central star is used to derive a limit to its magnitude: it is fainter than a magnitude of 22.4 in the visible. This is used to derive a lower limit to the temperature of the star. The Zanstra temperature is

  11. The shape of the LoTr 5 planetary nebula

    NARCIS (Netherlands)

    Brosch, N; Hoffman, Y

    1999-01-01

    We observed the large and faint planetary nebula around IN Com in H alpha and N II light with a coronagraphic charge-coupled device on the Wise Observatory reflector, blocking the light from the central star. Our goal was to provide a second image of the object with which to confirm the features

  12. ON AN ALTERNATIVE STATISTICAL DISTANCE SCALE FOR PLANETARY-NEBULAE - CATALOG WITH STATISTICAL DISTANCES TO PLANETARY-NEBULAE

    NARCIS (Netherlands)

    VANDESTEENE, GC; ZIJLSTRA, AA

    1994-01-01

    We have proposed a statistical method to determine distances to planetary nebulae. The method is based on an empirical correlation between the radio-continuum brightness temperature and radius. Here we present a catalog of distance determinations calculated using this method.

  13. The Herschel Planetary Nebula Survey (HerPlaNS)

    Science.gov (United States)

    Ueta, T.; Ladjal, D.; HerPlaNS Team

    2012-12-01

    The Herschel Planetary Nebula Survey (HerPlaNS, PI: T. Ueta) is one of the largest Herschel Open Time 1 program in which we explore the far-infrared aspects of 11 planetary nebulae (PNs) with the Herschel Space Observatory, exploiting its unprecedented capabilities in broadband photometry mapping, spectral mapping, and integral-field spectroscopy. We perform (1) deep PACS/SPIRE broadband mapping to account for the coldest dust component of the nebulae and determine the spatial distribution of the dusty haloes in the target PNs, (2) exhaustive PACS/SPIRE line mapping in far-IR atomic and molecular lines in two representative PNs to diagnose the energetics of the nebulae as a function of location in the nebulae, and (3) PACS/SPIRE spectral-energy-distribution spectroscopy at several positions in the target PNs to understand variations in the physical conditions as a function of location in the nebulae, to build a more complete picture of the interplay between the dust and gas components as a function of location in the nebulae. The HerPlaNS survey is distinguished from the existing guaranteed-time Key Program (KPGT), "Mass Loss of Evolved StarS" (MESS, PI: M. Groenewegen, including 10 PNs) by the extra dimension added by spectral mapping and integral-field spatio-spectroscopy that permit simultaneous probing of the gas and dust component in the target PNs. Through these investigations, we will consider the energetics of the entire gas-dust system as a function of location in the nebulae, which is a novel approach that has rarely been taken previously. HerPlaNS is conducted in collaboration with the Chandra Planetary Survey (ChanPlaNS, PI: J.H. Kastner) to furnish substantial PN data resources that would allow us—a community of PN astronomers—to tackle a multitude of unanswered issues in PN physics, from the shaping mechanisms of the nebulae to the energetics of the multi-phased gas-dust system surrounding the central white dwarf. These PN surveys, combined with

  14. Probing Shocks of the Young Planetary Nebula NGC 7027

    Science.gov (United States)

    Montez, Rodolfo

    2013-09-01

    The rapid evolution of the planetary nebula NGC 7027 provides a rare glimpse at the evolution of the shocks. We propose a detailed spatial and spectroscopic study of the shock conditions in NGC 7027 that will enhance and bridge our understanding of the shocks seen in other planetary nebula. Comparison between the Cycle 1 observation and a new Cycle 15 observation will (i) confirm the presence of the two components in the extended X-ray emission, (ii) measure the changes (spatial and spectral) in the components, and, (iii) provide a valuable trove of tests and inputs for shock conditions and hydrodynamical simulations. We rely on the unprecedented spatial resolution and soft-sensitivity of Chandra.

  15. A new planetary nebula in the outer reaches of the Galaxy

    DEFF Research Database (Denmark)

    Viironen, K.; Mampaso, A.; L. M. Corradi, R.

    2011-01-01

    A proper determination of the abundance gradient in the Milky Way requires the observation of objects at large galactiocentric distances. With this aim, we are exploring the planetary nebula population towards the Galactic Anticentre. In this article, the discovery and physico-chemical study...... of a new planetary nebula towards the Anticentre direction, IPHASX J052531.19+281945.1 (PNG 178.1-04.0), is presented. The planetary nebula was discovered from the IPHAS survey. Long-slit follow-up spectroscopy was carried out to confirm its planetary nebula nature and to calculate its physical...... and chemical characteristics. The newly discovered planetary nebula turned out to be located at a very large galactocentric distance (D_GC=20.8+-3.8 kpc), larger than any previously known planetary nebula with measured abundances. Its relatively high oxygen abundance (12+log(O/H) = 8.36+-0.03) supports...

  16. Spectrophotometry of Bowen resonance fluorescence lines in three planetary nebulae

    Science.gov (United States)

    O'Dell, C. R.; Miller, Christopher O.

    1992-01-01

    The results are presented of a uniquely complete, carefully reduced set of observations of the O III Bowen fluorescence lines in the planetary nebulae NGC 6210, NGC 7027, and NGC 7662. A detailed comparison with the predictions of radiative excitation verify that some secondary lines are enhanced by selective population by the charge exchange mechanism involving O IV. Charge exchange is most important in NGC 6210, which is of significantly lower ionization than the other nebulae. In addition to the principal Bowen lines arising from Ly-alpha pumping of the O III O1 line, lines arising from pumping of the O3 line are also observed. Comparison of lines produced by O1 and O3 with the theoretical predictions of Neufeld indicate poor agreement; comparison with the theoretical predictions of Harrington show agreement with NGC 7027 and NGC 7662.

  17. Abundance in the planetary nebulae NGC 6537 and He2-111

    NARCIS (Netherlands)

    Pottasch, [No Value; Beintema, DA; Feibelman, WA

    2000-01-01

    The ISO and IUE spectra of the bipolar planetary nebulae NGC 6537 and He2-111 are presented. These spectra are combined with the spectrum in the visual wavelength region from the nebulae to obtain a complete spectrum that is corrected for extinction. The chemical abundance of the nebulae is then

  18. Tracing the star stream through M31 using planetary nebula kinematics

    NARCIS (Netherlands)

    Merrett, HR; Kuijken, K; Merrifield, MR; Romanowsky, AJ; Douglas, NG; Napolitano, NR; Arnaboldi, M; Capaccioli, M; Freeman, KC; Gerhard, O; Evans, NW; Wilkinson, MI; Halliday, C; Bridges, TJ; Carter, D

    2003-01-01

    We present a possible orbit for the Southern Stream of stars in M31, which connects it to the Northern Spur. Support for this model comes from the dynamics of planetary nebulae (PNe) in the disc of M31: analysis of a new sample of 2611 PNe obtained using the Planetary Nebula Spectrograph reveals

  19. Radio synthesis observations of planetary nebulae. II. A search for sub-arcsecond structure

    International Nuclear Information System (INIS)

    Balick, B.; Terzian, Y.

    1976-01-01

    Observations of 11 planetary nebulae with spatial resolutions from 0''.2 to 2'' at 2695 and 8085 MHz failed to show any very bright structure smaller than about 2''. The observations are shown to be consistent with the present understanding of the temperatures and density distributions thought to typify most planetary nebulae

  20. Identification of faint central stars in extended, low-surface-brightness planetary nebulae

    International Nuclear Information System (INIS)

    Kwitter, K.B.; Lydon, T.J.; Jacoby, G.H.

    1988-01-01

    As part of a larger program to study the properties of planetary nebula central stars, a search for faint central stars in extended, low-surface-brightness planetary nebulae using CCD imaging is performed. Of 25 target nebulae, central star candidates have been identified in 17, with certainties ranging from extremely probable to possible. Observed V values in the central star candidates extend to fainter than 23 mag. The identifications are presented along with the resulting photometric measurements. 24 references

  1. Proto-planetary nebulae. I. The extreme bipolar nebulae M2-9 and M1-91

    International Nuclear Information System (INIS)

    Goodrich, R.W.

    1991-01-01

    Results are presented on a long-slit optical spectroscopy measurements of the prototype bipolar planetary nebula M2-9 and the M1-91 bipolar nebula, performed in order to determine the nature of the morphology of the wings of these two nebulae. It is concluded that the overall bipolar morphologies of these nebulae might be due to the orbital motions of binaries, with the orbital angular momentum vector defining the axis of the nebula. Secondary symmetries in the nebulae, such as the point-symmetric knots in M1-91, could be due to other symmetries, such as the rotation axis of one of the individual stars or the polar axis of the accretion disk. 39 refs

  2. Emission lines of Mg2 and Ca2 in planetary nebulae

    International Nuclear Information System (INIS)

    Gurzadyan, G.A.

    1979-01-01

    Conditions of exciting resonance lines in the emission of ionized magnesium (lambda lambda 2796+2803 Mg2) and calcium (lambda lambda 3934+3968 Ca2) in planetary nebulae have been analyzed. It is shown that the allowed lines are excited with the same mechanism, as the forbidden lines, i.e. inelastic electron collisions, but not with common fluorescence. The emission line lambda 2800 Mg2 of enough force can be observed only in the spectra of planetary nebulae with mean excitation (IC 2149) as well as in the spectra of diffuse nebulae. The line must not be observed in high-excited planetary nebulae (NGC 7026, 7662). The absence of emission lines H and K Ca2 in planetary nebulae spectra results from the fact, that their expected intensity is by 3-4 orders less than the intensity of the line lambda 2800 Mg2 or Hsub(β) hydrogen

  3. The internal kinematics of the planetary nebula NGC 650/1

    International Nuclear Information System (INIS)

    Taylor, K.

    1979-01-01

    Hα and [N II], lambda 6584 line profiles from the bright lobes of planetary nebula NGC 650/1 have been obtained. These emission lines show a very strong symmetrical triple-peak velocity structure, not observed previously to the author's knowledge in planetary nebulae. Models are tentatively proposed to explain both the velocity data and the nebula's optical appearance. The velocity splitting amounts to approximately 62 km/s and the rest frame of the nebula is found to have a heliocentric radial velocity of -19 +- 2 km/s. (author)

  4. The chemical composition of three planetary nebulae in the Magellanic clouds

    International Nuclear Information System (INIS)

    Dufour, R.J.; Killen, R.M.

    1977-01-01

    Emission-line intensities in the planetary nebulae Henize 67 in the Small Magellanic Cloud (SMC) and Henize 97 and 153 in the LMC along with the small SMC H II regions Henize 9, 61, and 81 were measured from photographic image-tube spectra taken with the 1.5 m telescope at Cerro Tololo. The relative abundances of H, He, N, O, Ne, S, and Ar in the nebulae were estimated and compared with the compositions of galactic planetary nebulae and previously studied H II regions in the Clouds. The results show that (1) the N/O ratios in the planetary nebulae are substantially higher than found in the H II regions of each Cloud; (2) He/H approx. = 0.18 in the SMC planetary nebula, but seems normal (approx.0.10) in the two LMC planetaries; and (3) the compositions of the three small SMC H II regions are similar to that of larger SMC H II regions studied previously. It is concluded that the N/H values in the shells of planetary nebulae may not depend on the metal content of the progenitor star as much as recent theoretical models suggest and that the N content of the gas in the Magellanic Clouds arises primarily from sources other than planetary nebulae

  5. UNUSUAL DUST EMISSION FROM PLANETARY NEBULAE IN THE MAGELLANIC CLOUDS

    International Nuclear Information System (INIS)

    Bernard-Salas, J.; Sloan, G. C.; Gutenkunst, S.; Houck, J. R.; Peeters, E.; Matsuura, M.; Tielens, A. G. G. M.; Zijlstra, A. A.

    2009-01-01

    We present a Spitzer Space Telescope spectroscopic study of a sample of 25 planetary nebulae (PNe) in the Magellanic Clouds (MCs). The low-resolution modules are used to analyze the dust features present in the infrared spectra. This study complements a previous work by the same authors where the same sample was analyzed in terms of neon and sulfur abundances. Over half of the objects (14) show emission of polycyclic aromatic hydrocarbons, typical of carbon-rich dust environments. We compare the hydrocarbon emission in our objects to those of Galactic H II regions and PNe, and Large Magellanic Cloud/Small Magellanic Cloud H II regions. Amorphous silicates are seen in just two objects, enforcing the now well known fact that oxygen-rich dust is less common at low metallicities. Besides these common features, some PNe show very unusual dust. Nine objects show a strong silicon carbide feature at 11 μm and 12 of them show magnesium sulfide emission starting at 25 μm. The high percentage of spectra with silicon carbide in the MCs is not common. Two objects show a broadband which may be attributed to hydrogenated amorphous carbon and weak low-excitation atomic lines. It is likely that these nebulae are very young. The spectra of the remaining eight nebulae are dominated by the emission of fine-structure lines with a weak continuum due to thermal emission of dust, although in a few cases the signal-to-noise ratio in the spectra is low, and weak dust features may not have been detected.

  6. The Σ − D relation for planetary nebulae: Preliminary analysis

    Directory of Open Access Journals (Sweden)

    Urošević D.

    2007-01-01

    Full Text Available An analysis of the relation between radio surface brightness and diameter, so-called Σ − D relation, for planetary nebulae (PNe is presented: i the theoretical Σ − D relation for the evolution of bremsstrahlung surface brightness is derived; ii contrary to the results obtained earlier for the Galactic supernova remnant (SNR samples, our results show that the updated sample of Galactic PNe does not severely suffer from volume selection effect - Malmquist bias (same as for the extragalactic SNR samples and; iii we conclude that the empirical S − D relation for PNe derived in this paper is not useful for valid determination of distances for all observed PNe with unknown distances. .

  7. Two-dimensional spectrophotometry of planetary nebulae by CCD imaging

    International Nuclear Information System (INIS)

    Jacoby, G.H.; Africano, J.L.; Quigley, R.J.; Western Washington Univ., Bellingham, WA)

    1987-01-01

    The spatial distribution of the electron temperature and density and the ionic abundances of O(+), O(2+), N(+), and S(+) have been derived from CCD images of the planetary nebulae NGC 40 and NGC 6826 taken in the important emission lines of forbidden O II, forbidden O III, H-beta, forbidden N II, and forbidden S II. The steps required in the derivation of the absolute fluxes, line, ratios, and ionic abundances are outlined and then discussed in greater detail. The results show that the CCD imaging technique for two-dimensional spectrophotometry can effectively compete with classical spectrophotometry, providing the added benefits of complete spatial coverage at seeing-disk spatial resolution. The multiplexing in the spatial dimension, however, results in a loss of spectral information, since only one emission line is observed at any one time. 37 references

  8. The radial velocities of planetary nebulae in NGC 3379

    Science.gov (United States)

    Ciardullo, Robin; Jacoby, George H.; Dejonghe, Herwig B.

    1993-09-01

    We present the results of a radial velocity survey of planetary nebulae (PNs) in the normal elliptical galaxy NGC 3379 performed with the Kitt Peak 4 m telescope and the NESSIE multifiber spectrograph. In two half-nights, we measured 29 PNs with projected galactocentric distances between 0.4 and 3.8 effective radii with an observational uncertainty of about 7 km/s. These data extend three times farther into the halo than any previous absorption-line velocity study. The velocity dispersion and photometric profile of the galaxy agrees extremely well with that expected from a constant mass-to-light ratio, isotropic orbit Jaffe model with M/L(B) about 7; the best-fitting anisotropic models from a quadratic programming algorithm also give M/L(B) about 7. The data are consistent with models that contain no dark matter within 3.5 effective radii of the galaxy's nucleus.

  9. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae.

    Science.gov (United States)

    Aller, L H; Keyes, C D

    1980-03-01

    Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic concentrations must be multiplied to obtain elemental abundances. Comparison with a large sample of nebulae for which extensive ground-based observations have been obtained shows nitrogen to be markedly enhanced in some of these objects. Possibly most, if not all, high-excitation nebulae evolve from stars that have higher masses than progenitors of nebulae of low-to-moderate excitation.

  10. Resolving the Disk-Halo Degeneracy using Planetary Nebulae

    Science.gov (United States)

    Aniyan, S.; Freeman, K. C.; Arnaboldi, M.; Gerhard, O.; Coccato, L.; Fabricius, M.; Kuijken, K.; Merrifield, M.

    2017-10-01

    The decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σ z ) of stars in the disk and its scale height (h z ), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: star-forming spirals have an old (kinematically hot) disk population and a young cold disk population. Both of these populations contribute to the integrated light spectra from which σ z is measured. The measured scale height h z is for the old disk population. In the Jeans equation, σ z and h z must pertain to the same population. We have developed techniques to extract the velocity dispersion of the old disk from integrated light spectra and from samples of planetary nebulae. We present the analysis of the disk kinematics of the galaxy NGC 628 using IFU data in the inner regions and planetary nebulae as tracers in the outer regions of the disk. We demonstrate that using the scale height of the old thin disk with the vertical velocity dispersion of the same population, traced by PNe, results in a maximal disk for NGC 628. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for NGC 628 appear like a submaximal disk.

  11. Gaseous nebulae

    International Nuclear Information System (INIS)

    Williams, R.E.

    1976-01-01

    Gaseous nebulae are large, tenuous clouds of ionized gas that are associated with hot stars and that emit visible light because of the energy that they receive from the ultraviolet radiation of the stars. Examples include H II regions, planetary nebulae, and nova/supernova remnants. The emphasis is on the physical processes that occur in gaseous nebulae as opposed to a study of the objects themselves. The introduction discusses thermodynamic vs. steady-state equilibrium and excitation conditions in a dilute radiation field. Subsequent sections take up important atomic processes in gaseous nebulae (particle--particle collision rates, radiative interaction rates, cross sections), the ionization equilibrium (sizes of H II regions, ionization of the heavier elements), kinetic temperature and energy balance (heating of the electrons, cooling of the electrons), and the spectra of gaseous nebulae (line fluxes in nebulae). 7 figures, 5 tables

  12. Bi-Abundance Ionisation Structure of the Wolf-Rayet Planetary Nebula PB 8

    Science.gov (United States)

    Danehkar, A.

    2018-01-01

    The planetary nebula PB 8 around a [WN/WC]-hybrid central star is one of planetary nebulae with moderate abundance discrepancy factors (ADFs 2-3), which could be an indication of a tiny fraction of metal-rich inclusions embedded in the nebula (bi-abundance). In this work, we have constructed photoionisation models to reproduce the optical and infrared observations of the planetary nebula PB 8 using a non-LTE stellar model atmosphere ionising source. A chemically homogeneous model initially used cannot predict the optical recombination lines. However, a bi-abundance model provides a better fit to most of the observed optical recombination lines from N and O ions. The metal-rich inclusions in the bi-abundance model occupy 5.6% of the total volume of the nebula, and are roughly 1.7 times cooler and denser than the mean values of the surrounding nebula. The N/H and O/H abundance ratios in the metal-rich inclusions are 1.0 and 1.7 dex larger than the diffuse warm nebula, respectively. To reproduce the Spitzer spectral energy distribution of PB 8, dust grains with a dust-to-gas ratio of 0.01 (by mass) were also included. It is found that the presence of metal-rich inclusions can explain the heavy element optical recombination lines, while a dual-dust chemistry with different grain species and discrete grain sizes likely produces the infrared continuum of this planetary nebula. This study demonstrates that the bi-abundance hypothesis, which was examined in a few planetary nebulae with large abundance discrepancies (ADFs > 10), could also be applied to those typical planetary nebulae with moderate abundance discrepancies.

  13. The ISO spectrum of the planetary nebula NGC 6302 - I. Observations

    NARCIS (Netherlands)

    Beintema, DA; Pottasch, [No Value

    The spectrum of the planetary nebula NGC 6302 is presented, as it was observed by the ISO short-wavelength spectrometer. The IUE spectrum observed at the same position with the same aperture is also presented.

  14. Dark-Matter Content of Early-Type Galaxies with Planetary Nebulae

    NARCIS (Netherlands)

    Napolitano, N.R.; Romanowsky, A.J.; Coccato, L; Capaccioli, M.; Douglas, N.G.; Noordermeer, E.; Merrifield, M.R.; Kuijken, K.; Arnaboldi, M.; Gerhard, O.; Freeman, K.C.; De Lorenzi, F.; Das, P.

    2007-01-01

    Abstract. We examine the dark matter properties of nearby early-type galaxies using plane- tary nebulae (PNe) as mass probes. We have designed a specialised instrument, the Planetary Nebula Spectrograph (PN.S) operating at the William Herschel telescope, with the purpose of measuring PN velocities

  15. The Spitzer IRS infrared spectrum and abundances of the planetary nebula IC 2448

    NARCIS (Netherlands)

    Guiles, S.; Bernard-Salas, J.; Pottasch, S. R.; Roellig, T. L.

    2007-01-01

    We present the mid-infrared spectrum of the planetary nebula IC 2448. In order to determine the chemical composition of the nebula, we use the infrared line fluxes from the Spitzer spectrum along with optical line fluxes from the literature and ultraviolet line fluxes from archival IUE spectra. We

  16. The distribution of mass in the planetary system and solar nebulae

    International Nuclear Information System (INIS)

    Weidenschilling, S.J.

    1977-01-01

    A model 'solar nebula' is constructed by adding the solar complement of light elements to each planet, using recent models of planetary compositions. Uncertainties in this approach are estimated. The computed surface density varies approximately as rsup(-3/2). Mercury, Mars and the asteroid belt are anomalously low in mass, but processes exist which would preferentially remove matter from these regions. Planetary masses and compositions are generally consistent with a monotonic density distribution in the primordial solar nebula. (Auth.)

  17. ABOUT TEMPERATURE FIELDS AND CONDITIONS OF GASEOUS CONDENSATION OF NEBULAES IN THE PLANETARY VORTEX

    Directory of Open Access Journals (Sweden)

    L. V. Klyuchinskaya

    2014-01-01

    Full Text Available New exact solution of the spherically-axissymmetric Eiler's equations, called as plan­etary vortex, is applied to the problem of formation in planetary nebula germs of planets due to the condensation of gases in the areas of vortex instability which calls the rings of planetary vortex. It is shown that the vortex perturbations causes changes in preassure and temperature at which the gases of nebula condense themselves, forming the germs of the planets.

  18. Planetary nebulae: understanding the physical and chemical evolution of dying stars.

    Science.gov (United States)

    Weinberger, R; Kerber, F

    1997-05-30

    Planetary nebulae are one of the few classes of celestial objects that are active in every part of the electromagnetic spectrum. These fluorescing and often dusty expanding gaseous envelopes were recently found to be quite complex in their dynamics and morphology, but refined theoretical models can account for these discoveries. Great progress was also made in understanding the mechanisms that shape the nebulae and the spectra of their central stars. In addition, applications for planetary nebulae have been worked out; for example, they have been used as standard candles for long-range distances and as tracers of the enigmatic dark matter.

  19. Collisional effects in He I lines and helium abundances in planetary nebulae

    International Nuclear Information System (INIS)

    Clegg, R.E.S.

    1987-01-01

    Attention is drawn to new, 19-state quantal calculations for collisional excitation by electron impact in neutral helium. Recommended empirical formulae are given for the collisional contribution to HeI recombination lines such as λλ4471, 5876 A in gaseous nebulae. Collisional ionization of metastable (2 3 S) He I is significant for high-temperature nebulae. Collisional transfers provide significant cooling in nebulae with low heavy-element abundances. Revised mean He/H ratios for three large samples of planetary nebulae are given. (author)

  20. A second list of new planetary nebulae found on United Kingdom 1.2-m Schmidt telescope plates

    International Nuclear Information System (INIS)

    Longmore, A.J.; Tritton, S.B.

    1980-01-01

    Positions, photographs and descriptions are given for 11 new planetary nebulae discovered on United Kingdom Schmidt plates. One of the planetary nebulae has the highest galactic latitude of any known planetary, and may be associated with a magnitude 9 G5 star. Near-infrared (J,H,K) magnitudes are given for the star. (author)

  1. A 'FIREWORK' OF H2 KNOTS IN THE PLANETARY NEBULA NGC 7293 (THE HELIX NEBULA)

    International Nuclear Information System (INIS)

    Matsuura, M.; Speck, A. K.; McHunu, B. M.; Tanaka, I.; Wright, N. J.; Viti, S.; Wesson, R.; Smith, M. D.; Zijlstra, A. A.

    2009-01-01

    We present a deep and wide field-of-view (4' x 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 μm H 2 v = 1 → 0 S(1) line. The excellent seeing (0.''4) at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2.'2-6.'4 from the central star (CS). At the inner edge and in the inner ring (up to 4.'5 from the CS), the knot often show a 'tadpole' shape, an elliptical head with a bright crescent inside and a long tail opposite to the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multipeaks within a tail. In the outer ring (4.'5-6.'4 from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H 2 surface brightness in the inner ring: H 2 exists only within the knots. Possible mechanisms which contribute to the shaping of the knots are discussed, including photoionization and streaming motions. A plausible interpretation of our images is that inner knots are being overrun by a faster wind, but that this has not (yet) reached the outer knots. Based on H 2 formation and destruction rates, H 2 gas can survive in knots from formation during the late asymptotic giant branch phase throughout the PN phase. These observations provide new constraints on the formation and evolution of knots, and on the physics of molecular gas embedded within ionized gas.

  2. Central stars of planetary nebulae: New spectral classifications and catalogue

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.

    2011-02-01

    Context. There are more than 3000 confirmed and probable known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We undertook a spectroscopic survey of central stars of PNe at low resolution and compiled a large list of central stars for which information was dispersed in the literature. Methods: We observed 45 PNs using the 2.15 m telescope at Casleo, Argentina. Results: We present a catalogue of 492 confirmed and probable CSPN and provide a preliminary spectral classification for 45 central star of PNe. This revises previous values of the proportion of CSPN with atmospheres poor in hydrogen in at least 30% of cases and provide statistical information that allows us to infer the origin of H-poor stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.

  3. Life after stellar death: Planetary Nebulae and Supernova Remnants

    Science.gov (United States)

    Boumis, P.

    2013-09-01

    Planetary nebulae (PNe) are powerful tracers of our Galaxy's star formation history. Their study can provide insight to the late stages of stellar evolution, the nucleosynthesis in low and intermediate mass stars (1-8Mo) and the chemical evolution of galaxies. Supernova explosions belong to the most spectacular events in the Universe. Supernova remnants (SNRs), which are the consequent results of these events and come from the late stages of massive stars (>8Mo), are among the strongest radio sources observed. They have a major influence on both the properties of the interstellar medium (ISM) and the evolution of galaxies as a whole. They enrich the ISM with heavy elements, release about 1051 ergs of energy, heat the ISM, compress the magnetic field, and efficiently accelerate, by their shock waves, energetic cosmic rays observed throughout the Galaxy. I will present results of our work on PNe and SNRs, which aims to (a) discover optical SNRs in the Galaxy, (b) study their morphology and kinematics, (c) characterize their properties (such as density, shock velocity etc.) and (d) provide information on their interaction with the ISM, using the "Aristarchos" among other telescopes.

  4. G25.5 + 0.2: a very young supernova remnant or a galactic planetary nebula?

    International Nuclear Information System (INIS)

    White, R.L.; Becker, R.H.

    1990-01-01

    G25.5 + 0.2, a radio source suggested by previous authors to be a very young galactic supernova remnant, is more likely to be a planetary nebula. Its IRAS colours and fluxes and its radio spectrum and morphology are all consistent with the properties of planetary nebulae; its radio flux and distance imply a large mass of ionized gas, which is expected from a Type I planetary nebula lying in the galactic plane. We suggest some definitive observations which should be able to determine whether this interesting object is a planetary nebula or a supernova remnant. (author)

  5. Dusty disks around central stars of planetary nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); De Marco, Orsola [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); Nordhaus, Jason [Center for Computational Relativity and Gravitation, and National Technical Institute for the Deaf, Rochester Institute of Technology, Rochester, NY 14623 (United States); Green, Joel [Department of Astronomy, The University of Texas, 1 University Station, C1400, Austin, TX 78712-0259 (United States); Rauch, Thomas; Werner, Klaus [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, D-72076 Tübingen (Germany); Chu, You-Hua, E-mail: gclayton@fenway.phys.lsu.edu, E-mail: orsola@science.mq.edu.au, E-mail: nordhaus@astro.rit.edu, E-mail: joel@astro.as.utexas.edu, E-mail: rauch@astro.uni-tuebingen.de, E-mail: werner@astro.uni-tuebingen.de, E-mail: chu@astro.uiuc.edu [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

    2014-06-01

    Only a few percent of cool, old white dwarfs (WDs) have infrared excesses interpreted as originating in small hot disks due to the infall and destruction of single asteroids that come within the star's Roche limit. Infrared excesses at 24 μm were also found to derive from the immediate vicinity of younger, hot WDs, most of which are still central stars of planetary nebulae (CSPNe). The incidence of CSPNe with this excess is 18%. The Helix CSPN, with a 24 μm excess, has been suggested to have a disk formed from collisions of Kuiper belt-like objects (KBOs). In this paper, we have analyzed an additional sample of CSPNe to look for similar infrared excesses. These CSPNe are all members of the PG 1159 class and were chosen because their immediate progenitors are known to often have dusty environments consistent with large dusty disks. We find that, overall, PG 1159 stars do not present such disks more often than other CSPNe, although the statistics (five objects) are poor. We then consider the entire sample of CSPNe with infrared excesses and compare it to the infrared properties of old WDs, as well as cooler post-asymptotic giant branch (AGB) stars. We conclude with the suggestion that the infrared properties of CSPNe more plausibly derive from AGB-formed disks rather than disks formed via the collision of KBOs, although the latter scenario cannot be ruled out. Finally, there seems to be an association between CSPNe with a 24 μm excess and confirmed or possible binarity of the central star.

  6. NEUTRON-CAPTURE ELEMENT ABUNDANCES IN MAGELLANIC CLOUD PLANETARY NEBULAE

    Energy Technology Data Exchange (ETDEWEB)

    Mashburn, A. L.; Sterling, N. C. [Department of Physics, University of West Georgia, 1601 Maple Street, Carrollton, GA 30118 (United States); Madonna, S. [Instituto de Astrofísica de Canarias, Departamento Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Dinerstein, Harriet L. [Department of Astronomy, University of Texas, 2515 Speedway, C1400, Austin, TX 78712-1205 (United States); Roederer, I. U. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Geballe, T. R., E-mail: awhite15@my.westga.edu, E-mail: nsterlin@westga.edu, E-mail: smadonna@iac.es, E-mail: harriet@astro.as.utexas.edu, E-mail: iur@umich.edu, E-mail: tgeballe@gemini.edu [Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720 (United States)

    2016-11-01

    We present near-infrared spectra of 10 planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n -capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s -process enrichments of Kr (0.6–1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5–0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2–3 M {sub ⊙} progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s -process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances from our spectra and find that [S/H] agrees with [Ar/H] to within 0.2 dex for most objects, but is lower than [O/H] by 0.2–0.4 dex in some PNe, possibly due to O enrichment via third dredge-up. Our results demonstrate that n -capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s -process enrichments to be studied in PN populations with well-determined distances.

  7. THE EVOLUTION OF THE KINEMATICS OF NEBULAR SHELLS IN PLANETARY NEBULAE IN THE MILKY WAY BULGE

    International Nuclear Information System (INIS)

    Richer, Michael G.; Lopez, Jose Alberto; Garcia-Diaz, Maria Teresa; Clark, David M.; Pereyra, Margarita; Diaz-Mendez, Enrique

    2010-01-01

    We study the line widths in the [O III]λ5007 and Hα lines for two groups of planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir (OAN-SPM) using the Manchester Echelle Spectrograph. The first sample includes objects early in their evolution, having high Hβ luminosities, but [O III]λ5007/Hβ 0.5. These planetary nebulae represent evolutionary phases preceding and following those of the objects studied by Richer et al. in 2008. Our sample of planetary nebulae with weak [O III]λ5007 has a line width distribution similar to that of the expansion velocities of the envelopes of asymptotic giant branch stars and shifted to systematically lower values as compared to the less evolved objects studied by Richer et al. The sample with strong He II λ4686 has a line width distribution indistinguishable from that of the more evolved objects from Richer et al., but a distribution in angular size that is systematically larger and so they are clearly more evolved. These data and those of Richer et al. form a homogeneous sample from a single Galactic population of planetary nebulae, from the earliest evolutionary stages until the cessation of nuclear burning in the central star. They confirm the long-standing predictions of hydrodynamical models of planetary nebulae, where the kinematics of the nebular shell are driven by the evolution of the central star.

  8. Abundances of planetary nebulae NGC 7662 and NGC 6741

    NARCIS (Netherlands)

    Pottasch, [No Value; Beintema, DA; Salas, JB; Feibelman, WA

    2001-01-01

    The ISO and IUE spectra of the elliptical nebulae NGC7662 and NGC6741 are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous

  9. Abundances of the planetary nebula Hu 1-2

    NARCIS (Netherlands)

    Pottasch, [No Value; Hyung, S; Aller, LH; Beintema, DA; Bernard-Salas, J; Feibelman, WA; Klockner, HR

    The ISO and IUE spectra of the "elliptical" nebula Hu 1-2 are presented. These spectra are combined with new, high resolution spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebula is then calculated and compared to

  10. Helium shell flashes and ionization of planetary nebulae. Pt. 2. FG Sge

    International Nuclear Information System (INIS)

    Tylenda, R.

    1980-01-01

    Theoretical models have been constructed to study time-dependent effects in the nebulae (He 1-5) associated with FG Sge. Two cases have been considered: recombination of an initially stationary nebula of moderate excitation (Case A), and nonequilibrium ionization (and subsequent recombination) of an initially neutral nebula by a thermal pulse in the central star (Case B). Comparison with the observed spectrum does not allow to distinguish definitely between both cases. There are slight indications that the present state of He 1-5 is better reproduced in Case B which is also preferable from the point of view of the present theoretical knowledge of observational appearances of helium shell flashes in planetary nebula nuclei. The nebula has a normal chemical composition. (author)

  11. Nebular Spectroscopy: A Guide on Hii Regions and Planetary Nebulae

    Science.gov (United States)

    Peimbert, Manuel; Peimbert, Antonio; Delgado-Inglada, Gloria

    2017-08-01

    We present a tutorial on the determination of the physical conditions and chemical abundances in gaseous nebulae. We also include a brief review of recent results on the study of gaseous nebulae, their relevance for the study of stellar evolution, galactic chemical evolution, and the evolution of the universe. One of the most important problems in abundance determinations is the existence of a discrepancy between the abundances determined with collisionally excited lines and those determined by recombination lines: this is called abundance discrepancy factor (ADF) problem, and we review results related to it. Finally, we discuss the possible reasons for the large t 2 values observed in gaseous nebulae.

  12. A Study of Planetary Nebulae using the Faint Object Infrared Camera for the SOFIA Telescope

    Science.gov (United States)

    Davis, Jessica

    2012-01-01

    A planetary nebula is formed following an intermediate-mass (1-8 solar M) star's evolution off of the main sequence; it undergoes a phase of mass loss whereby the stellar envelope is ejected and the core is converted into a white dwarf. Planetary nebulae often display complex morphologies such as waists or torii, rings, collimated jet-like outflows, and bipolar symmetry, but exactly how these features form is unclear. To study how the distribution of dust in the interstellar medium affects their morphology, we utilize the Faint Object InfraRed CAmera for the SOFIA Telescope (FORCAST) to obtain well-resolved images of four planetary nebulae--NGC 7027, NGC 6543, M2-9, and the Frosty Leo Nebula--at wavelengths where they radiate most of their energy. We retrieve mid infrared images at wavelengths ranging from 6.3 to 37.1 micron for each of our targets. IDL (Interactive Data Language) is used to perform basic analysis. We select M2-9 to investigate further; analyzing cross sections of the southern lobe reveals a slight limb brightening effect. Modeling the dust distribution within the lobes reveals that the thickness of the lobe walls is higher than anticipated, or rather than surrounding a vacuum surrounds a low density region of tenuous dust. Further analysis of this and other planetary nebulae is needed before drawing more specific conclusions.

  13. Central Stars of Planetary Nebulae in the SMC

    Science.gov (United States)

    Bianchi, Luciana

    2004-01-01

    In FUSE cycle 3's program C056 we studied four Central Stars of Planetary Nebulae (CSPN) in the Small Magellanic Could. All FUSE observations have been successfully completed and have been reduced and analyzed. The observation of one object (SMP SMC 5) appeared to be off-target and no useful stellar flux was gathered. For another observation (SMP SMC 1) the voltage problems resulted in the loss of data from one of the SiC detectors, but we were still able to analyze the remaining data. The analysis and the results are summarized below. The FUSE data were reduced using the latest available version of the FUSE calibration pipeline (CALFUSE v2.4). The flux of these SMC post-AGB objects is at the threshold of FUSE S sensitivity, and the targets required many orbit-long exposures, each of which typically had low (target) count-rates. The background subtraction required special care during the reduction, and was done in a similar manner to our FUSE cycle 2 BOO1 objects. The resulting calibrated data from the different channels were compared in the overlapping regions for consistency. The final combined, extracted spectra of each target was then modeled to determine the stellar and nebular parameters. The FUSE spectra, combined with archival HST spectra, have been analyzed using stellar atmospheres codes such as TLUSTY and CMFGEN to derive photospheric and wind parameters of the central stars, and with ISM models to determine the amount and temperature of the surrounding atomic and molecular hydrogen. We have combined these results with those of our cycle 4 (D034) program (CSPN of the LMC) in Herald & Bianchi 2004a (paper in preparation, will be submitted to ApJ in June 2004). Two of the three SMC objects analyzed were found to have significantly lower stellar temperatures than had been predicted using nebular photoionization models, indicating either a hotter ionizing companion or the existence of strong shocks in the nebular environment. The analysis also revealed that

  14. Detection of C60 and C70 in a young planetary nebula.

    Science.gov (United States)

    Cami, Jan; Bernard-Salas, Jeronimo; Peeters, Els; Malek, Sarah Elizabeth

    2010-09-03

    In recent decades, a number of molecules and diverse dust features have been identified by astronomical observations in various environments. Most of the dust that determines the physical and chemical characteristics of the interstellar medium is formed in the outflows of asymptotic giant branch stars and is further processed when these objects become planetary nebulae. We studied the environment of Tc 1, a peculiar planetary nebula whose infrared spectrum shows emission from cold and neutral C60 and C70. The two molecules amount to a few percent of the available cosmic carbon in this region. This finding indicates that if the conditions are right, fullerenes can and do form efficiently in space.

  15. A detailed study of the structure of the nested planetary nebula, Hb 12, the Matryoshka nebula

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D. M.; López, J. A. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Campus Ensenada, Ensenada, Baja California, 22860 (Mexico); Edwards, M. L. [LBT Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Winge, C., E-mail: dmclark@astrosen.unam.mx, E-mail: jal@astrosen.unam.mx, E-mail: medwards@lbto.org, E-mail: cwinge@gemini.edu [Gemini Observatory, Southern Operations Center, c/o AURA Inc., Casilla 603, La Serena (Chile)

    2014-11-01

    We present near-IR, integral field spectroscopic observations of the planetary nebula (PN) Hb 12 using Near-infrared Integral Field Spectrograph (NIFS) on Gemini-North. Combining NIFS with the adaptive optics system Altair, we provide a detailed study of the core and inner structure of this PN. We focus the analysis in the prominent emission lines [Fe II] (1.6436 μm), He I (2.0585 μm), H{sub 2} (2.1214 μm), and Br{sub γ} (2.16553 μm). We find that the [Fe II] emission traces a tilted system of bipolar lobes, with the northern lobe being redshifted and the southern lobe blueshifted. The [Fe II] emission is very faint at the core and only present close to the systemic velocity. There is no H{sub 2} emission in the core, whereas the core is prominent in the He I and Br{sub γ} recombination lines. The H{sub 2} emission is concentrated in equatorial arcs of emission surrounding the core and expanding at ∼30 km s{sup –1}. These arcs are compared with Hubble Space Telescope images and shown to represent nested loops belonging to the inner sections of a much larger bipolar structure that replicates the inner one. The He I and Br{sub γ} emission from the core clearly show a cylindrical central cavity that seems to represent the inner walls of an equatorial density enhancement or torus. The torus is 0.''2 wide (≡200 AU radius at a distance of 2000 pc) and expanding at ≤30 km s{sup –1}. The eastern wall of the inner torus is consistently more intense than the western wall, which could indicate the presence of an off-center star, such as is observed in the similar hourglass PN, MyCn 18. A bipolar outflow is also detected in Br{sub γ} emerging within 0.''1 from the core at ∼ ± 40 km s{sup –1}.

  16. Evolution of those nuclei of planetary nebulae that experience a final helium shell flash

    International Nuclear Information System (INIS)

    Iben, I. Jr.; Kaler, J.B.; Truran, J.W.; Renzini, A.

    1983-01-01

    We suggest that some of the central stars of planetary nebulae experience a final thermal pulse having achieved a white dwarf configuration and begun their descent along a cooling white dwarf sequence of nearly constant radius. A concrete theoretical calculation demonstrates that, during such a pulse, most of the hydrogen remaining in the star at pulse onset is incorporated into the helium-burning convective shell and completely burned, and that, following the pulse, the star swells briefly to red giant dimensions. The model then proceeds to burn helium on a long time scale, retracing in the H-R diagram approximately the same path that it followed while burning hydrogen during the initial excitation of the nebula, which has by now expanded considerably in extent. We identify as being in the postpulse, quiescent helium burning phase the central stars of the planetary nebulae d Abell 78, and the central stars of a group of related high-excitation objects. These nebulae all have the large radii often found in conjunction with central stars of low luminosity that are thought to be cooling along the white dwarf sequence; however, they have the high luminosities that are characteristic of much smaller nebulae whose nuclei are thought to be proceeding for the first time through the planetary nucleus regime in the (log L, log T/sub e/)-plane

  17. Photometric investigation of possible binary occurrence in the central stars of seventeen planetary nebulae

    International Nuclear Information System (INIS)

    Drummond, J.D. III.

    1980-01-01

    A comprehensive literature search was conducted for all possible bihary central stars in planetary nebulae. The results, which include all known and suspected visual, spectroscopic, and spectrum binaries, as well as all reported variable central stars, are presented in a series of tables. A photoelectric study was conducted in order to determine the status of short period (on the order of hours) variability of the central regions of seventeen planetary nebulae. Only the stellar appearing planetary nebula M1-2 (PK 133-8 0 1) was found to be variable. Its short (4.0002 hours) period suggests that it may be only the second eclipsing binary found among central stars to date. A method of concentric apertures was developed to determine the amount of light contributed by the central star vis-a-vis the nebula through a given aperture and filter. The procedure enabled UBV magnitudes and colors (and the errors) of central stars to be measured, including some in the sample of seventeen for which no previous values have been published. Mean nebular UBV magnitudes, surface brightnesses, and color indices were also found with the technique, and represent the first such published measurements. Various UBV two-parameter were constructed, revealing possible nebular/stellar sequences; a star-plus-nebula two-color diagram identifies three spectral classes of central stars, and two suspected binaries in the seventeen studied

  18. Periodic Light Variability in Twelve Carbon-rich Proto-Planetary Nebulae

    Science.gov (United States)

    Hrivnak, Bruce J.; Lu, Wenxian; Maupin, Richard E.; Spitzbart, Bradley D.

    2009-09-01

    We present the results of a long-term (14 year) photometric monitoring program of 12 carbon-rich proto-planetary nebulae (PPNs). PPNs are objects in the evolutionary transition between the AGB and planetary nebula phases. These 12 have bright central stars (V = 8-14 mag) with F-G spectral types and faint nebulae (as seen with the HST). All of the objects show a periodicity in their light variations, although there is also evidence for multiple periods or small period changes. The pulsation periods range from 35 to 153 days, with the longer periods correlated with later spectral types. In fact, a tight correlation is seen between the period and effective temperature. The light variations range from 0.15 to 0.7 mag and are larger for the cooler objects.

  19. VizieR Online Data Catalog: Abundances in Magellanic Cloud planetary nebulae (Monk+ 1988)

    Science.gov (United States)

    Monk, D. J.; Barlow, M. J.; Clegg, R. E. S.

    1996-10-01

    Optical spectroscopic data for 71 Planetary Nebulae (PN) in the Large and Small Magellanic Clouds have been analysed. The line fluxes have been used to determine nebular temperatures, densities, and the abundances of He, N, O, Ne and Ar, relative to H. In our sample there are 12 nebulae with N/O>=0.5, resembling Peimbert's Type I PN; six low-excitation objects [1VLE) nebulae [I(Hβ)>I(5007)], similar to the Galactic VLE class. Mean abundances have been calculated for the nebulae not in these special groups. After correction for collisional excitation contributions to the nebular He I lines, PN in the SMC and LMC yield mass fractions of Y=0.249+/-0.025 and Y=0.258+/-0.012, respectively. (4 data files).

  20. Measurement of the He II radiation field in planetary nebulae through Bowen fluorescence

    Science.gov (United States)

    Bhatia, A. K.; Kastner, S. O.

    1987-01-01

    Excitation of O III by He II is treated for sources over a useful range of densities to give accurate predictions of Bowen/non-Bowen line ratios. These are applied to recent observations of planetary nebulae to show that Bowen excitation increases monotonically with excitation class, and to deduce other important consequences.

  1. Dynamos in asymptotic-giant-branch stars as the origin of magnetic fields shaping planetary nebulae.

    Science.gov (United States)

    Blackman, E G; Frank, A; Markiel, J A; Thomas, J H; Van Horn, H M

    2001-01-25

    Planetary nebulae are thought to be formed when a slow wind from the progenitor giant star is overtaken by a subsequent fast wind generated as the star enters its white dwarf stage. A shock forms near the boundary between the winds, creating the relatively dense shell characteristic of a planetary nebula. A spherically symmetric wind will produce a spherically symmetric shell, yet over half of known planetary nebulae are not spherical; rather, they are elliptical or bipolar in shape. A magnetic field could launch and collimate a bipolar outflow, but the origin of such a field has hitherto been unclear, and some previous work has even suggested that a field could not be generated. Here we show that an asymptotic-giant-branch (AGB) star can indeed generate a strong magnetic field, having as its origin a dynamo at the interface between the rapidly rotating core and the more slowly rotating envelope of the star. The fields are strong enough to shape the bipolar outflows that produce the observed bipolar planetary nebulae. Magnetic braking of the stellar core during this process may also explain the puzzlingly slow rotation of most white dwarf stars.

  2. Chemical abundances and dust in planetary nebulae in the Galactic bulge

    NARCIS (Netherlands)

    Gutenkunst, S.; Bernard-Salas, J.; Pottasch, S. R.; Sloan, G. C.; Houck, J. R.

    2008-01-01

    We present mid-infrared Spitzer spectra of 11 planetary nebulae in the Galactic bulge. We derive argon, neon, sulfur, and oxygen abundances for them using mainly infrared line fluxes combined with some optical line fluxes from the literature. Due to the high extinction toward the bulge, the infrared

  3. Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study

    NARCIS (Netherlands)

    Sahai, Raghvendra; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W.

    1994-01-01

    Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and

  4. Planetary nebula velocities in the disc and bulge of M31

    NARCIS (Netherlands)

    Halliday, C.; Carter, D.; Bridges, T. J.; Jackson, Z. C.; Wilkinson, M. I.; Quinn, D. P.; Evans, N. W.; Douglas, N. G.; Merrett, H. R.; Merrifield, M. R.; Romanowsky, A. J.; Kuijken, K.; Irwin, M. J.

    2006-01-01

    We present radial velocities for a sample of 723 planetary nebulae in the disc and bulge of M31, measured using the WYFFOS fibre spectrograph on the William Herschel Telescope. Velocities are determined using the [OIII] lambda 5007 emission line. Rotation and velocity dispersion are measured to a

  5. Model planetary nebulae: the effect of shadowed filaments on low ionization potential ion radiation

    International Nuclear Information System (INIS)

    Katz, A.

    1977-01-01

    Previous homogeneous model planetary nebulae calculations No. 4 have yielded emission strengths for low ionization potential No. 4 ions which are considerably lower than those observed. Several attempts were to correct this problem by the inclusion of optically thin condensations, the use of energy flux distributions from stellar model calculations instead of blackbody spectrum stars, and the inclusion of dust in the nebulae. The effect that shadowed filaments have on the ionization and thermal structure of model nebulae and the resultant line strengths are considered. These radial filaments are shielded from the direct stellar ionizing radiation by optically thick condensations in the nebula. Theoretical observational evidence exists for the presence of condensations and filaments. Since the only source of ionizing photons in the shadowed filaments is due to diffuse photons produced by recombination, ions of lower ionization potential are expected to exist there in greater numbers than those found in the rest of the nebula. This leads to increased line strengths from these ions and increases their values to match the observational values. It is shown that these line strengths in the filaments increase by over one to two orders of magnitude relative to values found in homogeneous models. This results in an increase of approximately one order of magnitude for these lines when contributions from both components of the nebula are considered. The parameters that determine the exact value of the increase are the radial location of the filaments in the nebula and the fraction of the nebular volume occupied by the filaments

  6. Planck intermediate results XVIII. The millimetre and sub-millimetre emission from planetary nebulae

    DEFF Research Database (Denmark)

    Cardoso, J.-F.; Delabrouille, J.; Ganga, K.

    2015-01-01

    Late stages of stellar evolution are characterized by copious mass-loss events whose signature is the formation of circumstellar envelopes (CSE). Planck multi-frequency measurements have provided relevant information on a sample of Galactic planetary nebulae (PNe) in the important and relatively...... observed in its radio and millimetre emission has previously prevented constructing its SED. A morphological study of the Helix Nebula was also performed. Planck maps reveal, for the first time, the spatial distribution of the dust inside the envelope, allowing us to identify different components, the most...

  7. IRAS-17423-1755 - A MASSIVE POST-AGE STAR EVOLVING INTO THE PLANETARY-NEBULA STAGE

    NARCIS (Netherlands)

    RIERA, A; GARCIALARIO, P; MANCHADO, A; POTTASCH, [No Value; RAGA, AC

    1995-01-01

    IRAS 17423-1755 has been recognized as a new bipolar nebula during a multi-wavelength observational program of unidentified IRAS sources with far infrared colours similar to those of known planetary nebulae. B, V, R and H alpha CCD images show a clearly marked bipolar structure with a total

  8. Absolute spectrophotometry of the IC 2149, 4593, and NGC 6210 planetary nebulae in near infrared region

    International Nuclear Information System (INIS)

    Noskova, R.I.

    1976-01-01

    The absolute monochromatic energy flux (in ergs.cm -2 sec -1 ) was determined for the emission lines of the planetary nebulae IC2149, 4593 and NGC 6210 in the spectral interval lambda 6300-11000 A. The interstellar extinction Asub(β)=1.sup(m)3; O.sup(m)4; O.sup(m)6, accordingly, was estimated by using spectral lines HI of the Paschen and Balmer series. The energy distribution (in ergsxcm -2 xsec -1 1A -1 ) was found in summary continuous spectrum in the interval lambda 4000-10000 A. The attempt was made to separate the continuum of the nucleus and the nebula. The theoretical nebula continuous spectrum was calculated from lambda 3000 A to the radio range. The continuum, calibrated by menas of the flat part of the radiospectrum, linked well enough with the optical spectrum calculated here

  9. Abundances in Planetary Nebulae: an Autopsy of Low and Intermediate Mass Stars

    Science.gov (United States)

    Buell, James Francis

    In this work we report on the results of synthetic thermally pulsing asymptotic giant branch models (TP-AGB) and compare the results to the abundance ratios in a sample of planetary nebulae. We use updated the input parameters for mass-loss, the stellar luminosity, and dredge-up. We calculated models with masses between 0.8 solar masses and 8 solar masses. We also calculated models with (Fe/H) between -2.5 and 0.3. The effect of the first, second, and third dredge-up as well as hot-bottom burning are reported on. The analysis of a sample of Galactic bulge and disk planetary nebulae is also reported on.

  10. Dark-Matter Content of Early-Type Galaxies with Planetary Nebulae

    Science.gov (United States)

    Napolitano, N. R.; Romanowsky, A. J.; Coccato, L.; Capaccioli, M.; Douglas, N. G.; Noordermeer, E.; Merrifield, M. R.; Kuijken, K.; Arnaboldi, M.; Gerhard, O.; Freeman, K. C.; De Lorenzi, F.; Das, P.

    2008-05-01

    We examine the dark matter properties of nearby early-type galaxies using planetary nebulae (PNe) as mass probes. We have designed a specialised instrument, the Planetary Nebula Spectrograph (PN.S) operating at the William Herschel telescope, with the purpose of measuring PN velocities with best efficiency. The primary scientific objective of this custom-built instrument is the study of the PN kinematics in 12 ordinary round galaxies. Preliminary results showing a dearth of dark matter in ordinary galaxies (Romanowsky et al. 2003) are now confirmed by the first complete PN.S datasets. On the other hand early-type galaxies with a “regular” dark matter content are starting to be observed among the brighter PN.S target sample, thus confirming a correlation between the global dark-to-luminous mass virial ratio (fDM = MDM M*) and the galaxy luminosity and mass.

  11. High-speed knots in the hourglass shaped planetary nebula Hubble 12

    DEFF Research Database (Denmark)

    Vaytet, N. M. H.; Rushton, A. P.; Lloyd, M.

    2009-01-01

    We present a detailed kinematical analysis of the young compact hourglass-shaped planetary nebula Hb 12. We performed optical imaging and longslit spectroscopy of Hb 12 using the Manchester echelle spectrometer with the 2.1m San Pedro Martir telescope. We reveal, for the first time, the presence...... of end caps (or knots) aligned with the bipolar lobes of the planetary nebula shell in a deep [NII]6584 image of Hb 12. We measured from our spectroscopy radial velocities of 120 km/s for these knots. We have derived the inclination angle of the hourglass shaped nebular shell to be 65 degrees to the line...... of sight. It has been suggested that Hb 12's central star system is an eclipsing binary (Hsia et al. 2006) which would imply a binary inclination of at least 80 degrees. However, if the central binary has been the major shaping influence on the nebula then both nebula and binary would be expected to share...

  12. SMC SMP 24: A Newly Radio-Detected Planetary Nebula in the Small Magellanic Cloud

    Directory of Open Access Journals (Sweden)

    Bojicic, I. S.

    2010-12-01

    Full Text Available In this paper we report a new radio-continuum detection of an extragalactic planetary nebula (PN: SMC~SMP~24. We show the radio-continuum image of this PN and present the measured radio data. The newly reduced radio observations are consistent with the multi-wavelength data and derived parameters found in the literature. SMC~SMP~24 appears to be a young and compact PN, optically thick at frequencies below 2~GHz.

  13. SMC SMP 24: A newly radio-detected planetary nebula in the small Magellanic cloud

    Directory of Open Access Journals (Sweden)

    Bojičić I.S.

    2010-01-01

    Full Text Available In this paper we report a new radio-continuum detection of an extragalactic planetary nebula (PN: SMC SMP 24. We show the radio-continuum image of this PN and present the measured radio data. The newly reduced radio observations are consistent with the multi-wavelength data and derived parameters found in the literature. SMC SMP 24 appears to be a young and compact PN, optically thick at frequencies below 2 GHz.

  14. An Analysis and Classification of Dying AGB Stars Transitioning to Pre-Planetary Nebulae

    Science.gov (United States)

    Blake, Adam C.

    2011-01-01

    The principal objective of the project is to understand part of the life and death process of a star. During the end of a star's life, it expels its mass at a very rapid rate. We want to understand how these Asymptotic Giant Branch (AGB) stars begin forming asymmetric structures as they start evolving towards the planetary nebula phase and why planetary nebulae show a very large variety of non-round geometrical shapes. To do this, we analyzed images of just-forming pre-planetary nebula from Hubble surveys. These images were run through various image correction processes like saturation correction and cosmic ray removal using in-house software to bring out the circumstellar structure. We classified the visible structure based on qualitative data such as lobe, waist, halo, and other structures. Radial and azimuthal intensity cuts were extracted from the images to quantitatively examine the circumstellar structure and measure departures from the smooth spherical outflow expected during most of the AGB mass-loss phase. By understanding the asymmetrical structure, we hope to understand the mechanisms that drive this stellar evolution.

  15. IMAGING THE ELUSIVE H-POOR GAS IN THE HIGH adf PLANETARY NEBULA NGC 6778

    Energy Technology Data Exchange (ETDEWEB)

    García-Rojas, Jorge; Corradi, Romano L. M.; Jones, David; Rodríguez-Gil, Pablo; Cabrera-Lavers, Antonio [Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife (Spain); Monteiro, Hektor [Instituto de Física e Química, Universidade Federal de Itajubá, Av. BPS 1303-Pinheirinho, 37500-903, Itajubá (Brazil)

    2016-06-20

    We present the first direct image of the high-metallicity gas component in a planetary nebula (NGC 6778), taken with the OSIRIS Blue Tunable Filter centered on the O ii λ 4649+50 Å optical recombination lines (ORLs) at the 10.4 m Gran Telescopio Canarias. We show that the emission of these faint O ii ORLs is concentrated in the central parts of the planetary nebula and is not spatially coincident either with emission coming from the bright [O iii] λ 5007 Å collisionally excited line (CEL) or the bright H α recombination line. From monochromatic emission line maps taken with VIMOS at the 8.2 m Very Large Telescope, we find that the spatial distribution of the emission from the auroral [O iii] λ 4363 line resembles that of the O ii ORLs but differs from nebular [O iii] λ 5007 CEL distribution, implying a temperature gradient inside the planetary nebula. The centrally peaked distribution of the O ii emission and the differences with the [O iii] and H i emission profiles are consistent with the presence of an H-poor gas whose origin may be linked to the binarity of the central star. However, determination of the spatial distribution of the ORLs and CELs in other PNe and a comparison of their dynamics are needed to further constrain the geometry and ejection mechanism of the metal-rich (H-poor) component and hence, understand the origin of the abundance discrepancy problem in PNe.

  16. (C III lambda 1909/Si III lambda 1892) ratio as a diagnostic for planetary nebulae and symbiotic stars

    International Nuclear Information System (INIS)

    Feibelman, W.A.; Aller, L.H.; California Univ., Los Angeles)

    1987-01-01

    Suitable IUE archival material on planetary nebulae has been examined to determine the log R /F(lambda 1909 C III)/F(lambda 1892 Si III)/ as a discriminant for distinguishing planetary nebulae from symbiotic stars and related objects. The mean value of log R for 73 galactic planetaries is 1.4, while that of extragalactic planetaries appears to be slightly lower, and that for symbiotics is 0.3. The lower value of log R for symbiotics is easily understood as a consequence of their higher densities. A plot of log R versus N-epsilon indicates that 80 percent of the planetaries fall into the range of log R between 1.2 and 1.8, but some of the peculiar and bipolar nebulae fall below log R = 1.2. The corresponding N(C++)/N(Si++) ionic ratio varies over a large range. 53 references

  17. Registration of H2O and SiO masers in the Calabash Nebula to confirm the planetary nebula paradigm

    Science.gov (United States)

    Dodson, R.; Rioja, M.; Bujarrabal, V.; Kim, J.; Cho, S. H.; Choi, Y. K.; Youngjoo, Y.

    2018-05-01

    We report on the astrometric registration of very long baseline interferometry images of the SiO and H2O masers in OH 231.8+4.2, the iconic proto-planetary nebula also known as the Calabash nebula, using the Korean VLBI Network and source frequency phase referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the asymptotic giant branch star, driving the bilobe structure with the water masers in the outflow. We are able to trace the bulk motions for the H2O masers over the last few decades to be 19 km s-1 and deduce that the age of this expansion stage is 38 ± 2 yr. The combination of this result with the distance allows a full 3D reconstruction and confirms that the H2O masers lie on and expand along the known large-scale symmetry axis and that the outflow is only a few decades old, so mass loss is almost certainly ongoing. Therefore, we conclude that the SiO emission marks the stellar core of the nebular, the H2O emission traces the expansion, and there must be multiple epochs of ejection to drive the macro-scale structure.

  18. Registration of H2O and SiO masers in the Calabash Nebula, to confirm the Planetary Nebula paradigm

    Science.gov (United States)

    Dodson, R.; Rioja, M.; Bujarrabal, V.; Kim, J.; Cho, SH; Choi, YK; Youngjoo, Y.

    2018-01-01

    We report on the astrometric registration of VLBI images of the SiO and H2O masers in OH 231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the AGB star, driving the bi-lobe structure with the water masers in the out-flow. We are able to trace the bulk motions for the H2O masers over the last few decades to be 19 km s-1 and deduce that the age of this expansion stage is 38±2 years. The combination of this result with the distance allows a full 3D reconstruction, and confirms that the H2O masers lie on and expand along the known large-scale symmetry axis and that the outflow is only a few decades old, so mass loss is almost certainly on-going. Therefore we conclude that the SiO emission marks the stellar core of the nebular, the H2O emission traces the expansion, and that there must be multiple epochs of ejection to drive the macro-scale structure.

  19. Stability of the hydrogenated benzene in the PDR of the planetary nebula NGC 7027

    Science.gov (United States)

    Quitian-Lara, Heidy M.; Wolff, Wania; Boechat-Roberty, Heloisa M.

    2017-07-01

    Polycyclic aromatic hydrocarbons, (PAHs), constituted by benzene (C6H6) rings, as well as hydrogenated PAHs (Hn-PAHs), compounds with excess peripheral H atoms, emit infrared bands (3-12 μm) due to their vibrational transitions. These molecules are present in different astrophysical environments. For example, the band at 3.3μm, assigned to vibration of aromatic C-H bonds, is generally accompanied by the band at 3.4μm, assigned to vibration of aliphatic C-H bonds. The abundances of these molecules in circumstellar environments depend on the rates of formation and destruction by UV and X-rays radiation. We study experimentally the photoionization and photodissociation of the cyclohexane molecule (C6H12), a prototype Hn-PAH, using synchrotron radiation at UV (10-100 eV) and soft X-ray (280-310 eV) energies and the time-of-flight mass spectrometry. The measurements were performed at Brazilian National Light Synchrotron (LNLS) using the toroidal grating monochromator (TGM) beamline. From the mass spectra of ionic fragments produced by the interaction of photons with the molecule in gas phase, the production of each ion was quantified as a function of the photon energy. Moreover, the stability of C6H12 and C6H6 was analyzed by the identification of the produced ions. A greater production of ethyl (C2Hn+) and propyl (C4Hn+) ion groups was observed from the photodissociation of C6H12. We determined the photon flux as a function of the energy in the photodissociation region (PDR) of the planetary nebula NGC 7027, taking into account the attenuation caused by the H and the dust grains. From these photon flux values and the photoionization and photodissociation cross-sections, the ionization and destruction rates of C6H12 and C6H6 were determined. We concluded that the aromatic structure is more stable than the aliphatic structure against UV and X-ray radiation emitted by central star. Acknowledgments: CNPq, CAPES, LNLS.

  20. A D'-type symbiotic binary in the planetary nebula SMP LMC 88

    Science.gov (United States)

    Iłkiewicz, Krystian; Mikołajewska, Joanna; Miszalski, Brent; Kozłowski, Szymon; Udalski, Andrzej

    2018-05-01

    SMP LMC 88 is one of the planetary nebulae (PNe) in the Large Magellanic Cloud. We identify in its spectrum Raman scattered O VI lines at 6825 and 7083 Å. This unambiguously classifies the central object of the nebula as a symbiotic star (SySt). We identified the cold component to be a K-type giant, making this the first D'-type (yellow) SySt discovered outside the Galaxy. The photometric variability in SMP LMC 88 resembles the orbital variability of Galactic D'-type SySt with its low amplitude and sinusoidal light-curve shape. The SySt classification is also supported by the He I diagnostic diagram.

  1. A Model for the Dynamical and Ionization Structure of Planetary Nebula IC 418

    Directory of Open Access Journals (Sweden)

    J. Ghanbari

    1997-04-01

    Full Text Available   The interacting two winds model and a spherical density distribution function are introduced to study the dynamical and ionization structure of the planetary nebula IC 418. A fast wind with a mechanical luminousity  2/34×1034erg.s-1 of interacts with a super wind with a mass-loss rate of  2×10-5M(°yr-1 and  a velocity of 10 , and produces a dense and luminous medium.   In this model, the expansion velocities of OI and HI lines are predicted to be 11 and 10.5kms-1 , respectively. The calculated dynamical time-scale 1033yr for the nebula is in good agreement with the evolution time of the central star after the interaction of the two winds. Our calculations give a luminosity  0.05M(°of for the central star

  2. Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae.

    Science.gov (United States)

    Keenan, F P; Aller, L H; Ramsbottom, C A; Bell, K L; Crawford, F L; Hyung, S

    2000-04-25

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed.

  3. The stellar seismology of hot white dwarfs and planetary nebula nuclei

    Science.gov (United States)

    Kawaler, Steven D.

    1987-01-01

    The pulsation properties of hot white dwarfs make it possible to determine their mass, surface composition, rotation, and rate of evolution, and provide constraints on their internal structure. Period spacings are sensitive measures of stellar mass and indicate surface layer structure. Measurement of the rate of period change for these stars provide a way to determine their cooling rates. Attention is also given to how well (or poorly) models of excitation of the pulsations fit within current models of planetary nebula nuclei and hot white dwarfs.

  4. 8-13 μm spectral observations of eight moderately extended planetary nebulae

    International Nuclear Information System (INIS)

    Roche, P.F.; Aitken, D.K.; Whitmore, B.

    1983-01-01

    8-13 μm spectra of eight moderately extended planetary nebulae have been obtained at a resolution of 0.24 μm using a 20-arcsec circular aperture. More compact planetaries which have been studied in this way generally show a strong continuum due to emission from dust, together with fine structure line emission. In contrast, these more extended objects have very weak continuum emission, and are dominated by fine structure line emission, especially by [S IV] which in several cases accounts for most of the broad-band 10 μm flux. There appears to be very little warm (>approx.= to 150 K) dust in some of these objects. (author)

  5. Emission Lines of O III in The Optical and Ultraviolet Spectra of Planetary Nebulae

    Science.gov (United States)

    Crawford, F. L.; Keenan, F. P.; Aggarwal, K. M.; Aller, L. H.; Feibelman, W. A.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    Recent R-matrix calculations of electron impact excitation rates in 0 III are used to calculate electron temperature and density-dependent emission line ratios R (sub 1) = I(4363 Angstroms)/ I(4960 Angstroms + 5007 Angstroms), R (sub 2) = I(1661 Angstroms + 1667 Angstroms)/ I(4960 Angstroms + 5007 Angstroms) and R (sub 3)= I(2322 Angstroms)/ I(1661 Angstroms + 1667 Angstroms), for a range of electron temperatures (7500 less than or equal to Te less than or equal to 30 000 K) and densities (10 (exp 4) less than or equal to N (sub e) less than or equal to 10 (exp 7) per cubic centimeters) applicable to gaseous nebulae. The ratio-ratio diagrams (R (sub 1), R (sub 2)) and (R (sub 1), R (sub 3)) should, in principle, allow the simultaneous determination of T (sub e) and N (sub e) from measurements of the 0 III features in a spectrum. Plasma parameters derived for a sample of high-excitation planetary nebulae from (R (sub 1), R (sub 2)) and (R (sub 1), R (sub 3)) measurements, produced using a combination of ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE) and optical data from a number of observing runs, are found to show excellent internal consistency. They also show, in general, good agreement with the values of Te and Ne estimated from other line ratios in the nebulae, therefore providing observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation.

  6. YOUNG PLANETARY NEBULAE: HUBBLE SPACE TELESCOPE IMAGING AND A NEW MORPHOLOGICAL CLASSIFICATION SYSTEM

    International Nuclear Information System (INIS)

    Sahai, Raghvendra; Villar, Gregory G.; Morris, Mark R.

    2011-01-01

    Using Hubble Space Telescope images of 119 young planetary nebulae (PNs), most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects. This system generalizes a recently devised system for pre-planetary nebulae, which are the immediate progenitors of PNs. Unlike previous classification studies, we have focused primarily on young PNs rather than all PNs, because the former best show the influences or symmetries imposed on them by the dominant physical processes operating at the first and primary stage of the shaping process. Older PNs develop instabilities, interact with the ambient interstellar medium, and are subject to the passage of photoionization fronts, all of which obscure the underlying symmetries and geometries imposed early on. Our classification system is designed to suffer minimal prejudice regarding the underlying physical causes of the different shapes and structures seen in our PN sample, however, in many cases, physical causes are readily suggested by the geometry, along with the kinematics that have been measured in some systems. Secondary characteristics in our system, such as ansae, indicate the impact of a jet upon a slower-moving, prior wind; a waist is the signature of a strong equatorial concentration of matter, whether it be outflowing or in a bound Keplerian disk, and point symmetry indicates a secular trend, presumably precession, in the orientation of the central driver of a rapid, collimated outflow.

  7. A SNAPshot Emission-line Imaging Survey of Very Low Excitation Planetary Nebulae

    Science.gov (United States)

    Sahai, Raghvendra

    1996-07-01

    We propose a "snapshot" emission-line imaging survey of a set of 30 very young planetary nebulae {PNe} selected on the basis of their very low excitation {VLE} characteristics, as evidenced by their very low O IIILambda5007, 4959 to H Alpha line flux ratios. These data will provide a unique, comprehensive dataset of images to address the issue of how AGB stars evolve into PNe. Planetary nebulae show a dazzling variety of structures not apparent in the circumstellar envelopes of the AGB stars from which they evolve. It is believed that the physical phenomena which shape the PNe occur early in thee formation history, involving the hydrodynamic interaction of one or more fast winds with the slower AGB mass-outflow. However, since the youngest PNe, which retain the clearest visible signatures of these phenomena, are very compact {VLE PNe, which together with distances and expansion velocities, will allow detailed tests of stellar evolutionary models. Classification of the morphological structures observed in this sample of very young PNe, and statistical comparisons with more evolved PNe populations, will set new constraints on hydrodynamical models of nebular evolution.

  8. Discovery of a [WO] central star in the planetary nebula Th 2-A

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.; Díaz, R. J.; Niemela, V. S.

    2008-09-01

    Context: About 2500 planetary nebulae are known in our Galaxy but only 224 have central stars with reported spectral types in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996). Aims: We have started an observational program aiming to increase the number of PN central stars with spectral classification. Methods: By means of spectroscopy and high resolution imaging, we identify the position and true nature of the central star. We carried out low resolution spectroscopic observations at CASLEO telescope, complemented with medium resolution spectroscopy performed at Gemini South and Magellan telescopes. Results: As a first outcome of this survey, we present for the first time the spectra of the central star of the PN Th 2-A. These spectra show emission lines of ionized C and O, typical in Wolf-Rayet stars. Conclusions: We identify the position of that central star, which is not the brightest one of the visual central pair. We classify it as of type [WO 3]pec, which is consistent with the high excitation and dynamical age of the nebula. Based on data collected at (i) the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina; (ii) the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile; (iii) the 8 m Gemini South Telescope, Chile.

  9. On the Radio-emitting Particles of the Crab Nebula: Stochastic Acceleration Model

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Shuta J. [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan); Asano, Katsuaki, E-mail: sjtanaka@center.konan-u.ac.jp [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa City, Chiba, 277-8582 (Japan)

    2017-06-01

    The broadband emission of pulsar wind nebulae (PWNe) is well described by non-thermal emissions from accelerated electrons and positrons. However, the standard shock acceleration model of PWNe does not account for the hard spectrum in radio wavelengths. The origin of the radio-emitting particles is also important to determine the pair production efficiency in the pulsar magnetosphere. Here, we propose a possible resolution for the particle energy distribution in PWNe; the radio-emitting particles are not accelerated at the pulsar wind termination shock but are stochastically accelerated by turbulence inside PWNe. We upgrade our past one-zone spectral evolution model to include the energy diffusion, i.e., the stochastic acceleration, and apply the model to the Crab Nebula. A fairly simple form of the energy diffusion coefficient is assumed for this demonstrative study. For a particle injection to the stochastic acceleration process, we consider the continuous injection from the supernova ejecta or the impulsive injection associated with supernova explosion. The observed broadband spectrum and the decay of the radio flux are reproduced by tuning the amount of the particle injected to the stochastic acceleration process. The acceleration timescale and the duration of the acceleration are required to be a few decades and a few hundred years, respectively. Our results imply that some unveiled mechanisms, such as back reaction to the turbulence, are required to make the energies of stochastically and shock-accelerated particles comparable.

  10. Distinguishing between HII regions and planetary nebulae with Hi-GAL, WISE, MIPSGAL, and GLIMPSE

    Science.gov (United States)

    Anderson, L. D.; Zavagno, A.; Barlow, M. J.; García-Lario, P.; Noriega-Crespo, A.

    2012-01-01

    Context. H II regions and planetary nebulae (PNe) both emit at radio and infrared (IR) wavelengths, and angularly small H II regions can be mistaken for PNe. This problem of classification is most severe for H II regions in an early evolutionary stage, those that are extremely distant, or those that are both young and distant. Previous work has shown that H II regions and PNe can be separated based on their infrared colors. Aims: Using data from the Herschel Hi-GAL survey, as well as WISE and the Spitzer MIPSGAL and GLIMPSE surveys, we wish to establish characteristic IR colors that can be used to distinguish between H II regions and PNe. Methods: We perform aperture photometry measurements for a sample of 126 H II regions and 43 PNe at wavelengths from 8.0 μm to 500 μm. Results: We find that H II regions and PNe have distinct IR colors. The most robust discriminating color criteria are [F12/F8] 1.3, and [F160/F24] > 0.8 (or alternately [F160/F22] > 0.8), where the brackets indicate the log of the flux ratio. All three of these criteria are individually satisfied by over 98% of our sample of H II regions and by ~10% of our sample of PNe. Combinations of these colors are more robust in separating the two populations; for example all H II regions and no PNe satisfy [F12/F8] F22] > 0.8. When applied to objects of unknown classification, these criteria prove useful in separating the two populations. The dispersion in color is relatively small for H II regions; this suggests that any evolution in these colors with time for H II regions must be relatively modest. The spectral energy distributions (SEDs) of H II regions can be separated into "warm" and "cold" components. The "cold" component is well-fit by a grey-body of temperature 25 K. The SEDs of nearly two-thirds of our sample of H II regions peak at 160 μm and one third peak at 70 μm. For PNe, 67% of the SEDs peak at 70 μm, 23% peak at either 22 μm or 24 μm, and 9% (two sources) peak at 160 μm. Herschel is

  11. The Hong Kong/AAO/Strasbourg Hα (HASH) Planetary Nebula Database

    Science.gov (United States)

    Bojičić, Ivan S.; Parker, Quentin A.; Frew, David J.

    2017-10-01

    The Hong Kong/AAO/Strasbourg Hα (HASH) planetary nebula database is an online research platform providing free and easy access to the largest and most comprehensive catalogue of known Galactic PNe and a repository of observational data (imaging and spectroscopy) for these and related astronomical objects. The main motivation for creating this system is resolving some of long standing problems in the field e.g. problems with mimics and dubious and/or misidentifications, errors in observational data and consolidation of the widely scattered data-sets. This facility allows researchers quick and easy access to the archived and new observational data and creating and sharing of non-redundant PN samples and catalogues.

  12. Probing the dynamics of elliptical galaxies by planetary nebulae in the framework of MOdified Newtonian Dynamics

    Science.gov (United States)

    Tian, Yong; Ko, Chung-Ming

    2015-08-01

    Planetary nebulae (PNe) at large distances from the centre of a galaxy provide us a tool to study its dynamics there. Romanowsky et al. (2003) reported the dynamics of three luminous elliptical galaxies up to 6 effective radii, and all of them can be explained by Newtonian dynamics without dark matter. Milgrom & Sanders (2003) deem that the result can be understood in the framework of MOND (MOdified Newtonian dynamics). We revisit this problem as more measurements are available in the past decade. In this contribution, we present our result on 7 elliptical galaxies with PNe data up to 6-8 effective radii and also stellar data from SAURON. We conclude that MOND can well explain the dynamics of all these galaxies.

  13. Dynamics of elliptical galaxies with planetary nebulae in modified Newtonian dynamics

    Science.gov (United States)

    Tian, Yong; Ko, Chung-Ming

    2016-10-01

    The dynamics of an elliptical galaxy within a couple of effective radii can be probed effectively by stars. However, at larger distances planetary nebulae (PNe) replace stars as the tracer of the dynamics. Making use of the motion of PNe, Romanowsky et al. measured the dynamics of three luminous elliptical galaxies (NGC821, NGC3379 and NGC4494) at large distances from the galactic centre. They found that little dark matter is needed up to six effective radii. Milgrom & Sanders showed that this result can be understood in the framework of MOdified Newtonian Dynamics (MOND). As more data are available in the past decade, we revisit this problem. We combine PNe data (up to six to eight effective radii) and stellar data from SAURON of seven elliptical galaxies, including those three galaxies in Romanowsky et al. with updated data and four other galaxies which have not been analysed before. We conclude that the dynamics of these galaxies can be well explained by MOND.

  14. AKARI/IRC NEAR-INFRARED SPECTRAL ATLAS OF GALACTIC PLANETARY NEBULAE

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Ryou [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Onaka, Takashi; Sakon, Itsuki [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Matsuura, Mikako [School of Physics and Astronomy, Cardiff University, Queen’s Buildings, 5 The Parade, Roath, Cardiff CF24 3AA (United Kingdom); Kaneda, Hidehiro, E-mail: ohsawa@ioa.s.u-tokyo.ac.jp [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)

    2016-04-15

    Near-infrared (2.5–5.0 μm) low-resolution (λ/Δλ ∼ 100) spectra of 72 Galactic planetary nebulae (PNe) were obtained with the Infrared Camera (IRC) in the post-helium phase. The IRC, equipped with a 1′ × 1′ window for spectroscopy of a point source, was capable of obtaining near-infrared spectra in a slit-less mode without any flux loss due to a slit. The spectra show emission features including hydrogen recombination lines and the 3.3–3.5 μm hydrocarbon features. The intensity and equivalent width of the emission features were measured by spectral fitting. We made a catalog providing unique information on the investigation of the near-infrared emission of PNe. In this paper, details of the observations and characteristics of the catalog are described.

  15. Optical Spectra of Radio Planetary Nebulae in the Small Magellanic Cloud

    Directory of Open Access Journals (Sweden)

    Payne, J. L.

    2008-06-01

    Full Text Available We present preliminary results from spectral observations of four (4 candidate radio sources co-identified with known planetary nebulae (PNe in the Small Magellanic Cloud (SMC. These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA surveys of the SMC at 1.42 and 2.37~GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (4arcsec/2arcsec. Optical PNe and radio candidates are within 2arcsec and may represent a sub-population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6~$M_odot$ or greater, supporting the existence of PNe progenitor central stars with masses up to 8 $M_odot$.

  16. Optical spectra of radio planetary nebulae in the small Magellanic cloud

    Directory of Open Access Journals (Sweden)

    Payne J.L.

    2008-01-01

    Full Text Available We present preliminary results from spectral observations of four (4 candidate radio sources co-identified with known planetary nebulae (PNe in the Small Magellanic Cloud (SMC. These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA surveys of the SMC at 1.42 and 2.37 GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (400 /200 . Optical PNe and radio candidates are within 200 and may represent a sub- population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6 Mo or greater, supporting the existence of PNe progenitor central stars with masses up to 8 Mo.

  17. Extinction of planetary nebulae and the turbulent structure of the galaxy

    International Nuclear Information System (INIS)

    Lerche, I.; Milne, D.K.

    1980-01-01

    Fluctuations in the extinction of planetary nebulae provide strong support for the concept of a turbulent interstellar medium. We have analyzed theoretically the mean extinction and its variance as a function of height, z, above the galactic plane. The mean increases monotonically, and exponentially, to a saturation level. The variance increases as z 2 for small z and has damped oscillations for intermediate z, before levelling off at large z. The observed mean extinction and the observed variance are found to be in excellent agreement with these theoretical deductions. The spatial scale of the mean extinction is estimated to be 100 pc; the oscillation scale of the variance and the damping scale of the oscillations are estimated to be about 200 +- 100 pc. The rms level of density fluctuations in the absorbing material causing the extinction is about equal to the mean value

  18. Imaging the elusive H-poor gas in planetary nebulae with large abundance discrepancy factors

    Science.gov (United States)

    García-Rojas, Jorge; Corradi, Romano L. M.; Boffin, Henri M. J.; Monteiro, Hektor; Jones, David; Wesson, Roger; Cabrera-Lavers, Antonio; Rodríguez-Gil, Pablo

    2017-10-01

    The discrepancy between abundances computed using optical recombination lines (ORLs) and collisionally excited lines (CELs) is a major, unresolved problem with significant implications for the determination of chemical abundances throughout the Universe. In planetary nebulae (PNe), the most common explanation for the discrepancy is that two different gas phases coexist: a hot component with standard metallicity, and a much colder plasma enhanced in heavy elements. This dual nature is not predicted by mass loss theories, and direct observational support for it is still weak. In this work, we present our recent findings that demonstrate that the largest abundance discrepancies are associated with close binary central stars. OSIRIS-GTC tunable filter imaging of the faint O ii ORLs and MUSE-VLT deep 2D spectrophotometry confirm that O ii ORL emission is more centrally concentrated than that of [Oiii] CELs and, therefore, that the abundance discrepancy may be closely linked to binary evolution.

  19. PLANETARY NEBULAE DETECTED IN THE SPITZER SPACE TELESCOPE GLIMPSE II LEGACY SURVEY

    International Nuclear Information System (INIS)

    Zhang Yong; Sun Kwok

    2009-01-01

    We report the result of a search for the infrared counterparts of 37 planetary nebulae (PNs) and PN candidates in the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire II (GLIMPSE II) survey. The photometry and images of these PNs at 3.6, 4.5, 5.8, 8.0, and 24 μm, taken through the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS), are presented. Most of these nebulae are very red and compact in the IRAC bands, and are found to be bright and extended in the 24 μm band. The infrared morphology of these objects are compared with Hα images of the Macquarie-AAO-Strasbourg (MASH) and MASH II PNs. The implications for morphological difference in different wavelengths are discussed. The IRAC data allow us to differentiate between PNs and H II regions and be able to reject non-PNs from the optical catalog (e.g., PNG 352.1 - 00.0). Spectral energy distributions are constructed by combing the IRAC and MIPS data with existing near-, mid-, and far-IR photometry measurements. The anomalous colors of some objects allow us to infer the presence of aromatic emission bands. These multi-wavelength data provide useful insights into the nature of different nebular components contributing to the infrared emission of PNs.

  20. Ages of evolved low mass stars: Central stars of planetary nebulae and white dwarfs

    Directory of Open Access Journals (Sweden)

    Costa R.D.D.

    2013-03-01

    Full Text Available We have developed several methods to estimate the ages of central stars of planetary nebulae (CSPN, which are based either on observed nebular properties or on data from the stars themselves. Our goal is to derive the age distribution of these stars and compare the results with empirical distributions for CSPN and white dwarfs. We have initially developed three methods based on nebular abundances, using (i an age-metallicity relation which is also a function of the galactocentric distance; (ii an age-metallicity relation obtained for the galactic disk, and (iii the central star masses derived from the observed nitrogen abundances. In this work we present two new, more accurate methods, which are based on kinematic properties: (I in this method, the expected rotation velocities of the nebulae around the galactic centre at their galactocentric distances are compared with the predicted values for the galactic rotation curve, and the differences are attributed to the different ages of the evolved stars; (II we determine directly the U, V, W, velocity components of the stars, as well as the velocity dispersions, and use the dispersion-age relation by the Geneva-Copenhagen survey. These methods were applied to two large samples of galactic CSPN. We conclude that most CSPN in the galactic disk have ages under 5 Gyr, and that the age distribution is peaked around 1 to 3 Gyr.

  1. Interpretation of two compact planetary nebulae, IC 4997 and NGC 6572, with aid of theoretical models.

    Science.gov (United States)

    Hyung, S; Aller, L H

    1993-01-15

    Observations of two dense compact planetary nebulae secured with the Hamilton Echelle spectrograph at Lick Observatory combined with previously published UV spectra secured with the International Ultraviolet Explorer enable us to probe the electron densities and temperatures (plasma diagnostics) and ionic concentrations in these objects. The diagnostic diagrams show that no homogenous model will work for these nebulae. NGC 6572 may consist of an inner torordal ring of density 25,000 atoms/cm3 and an outer conical shell of density 10,000 atoms/cm3. The simplest model of IC 4997 suggests a thick inner shell with a density of about 107 atoms/cm3 and an outer envelope of density 10,000 atoms/cm3. The abundances of all elements heavier than He appear to be less than the solar values in NGC 6572, whereas He, C, N, and O may be more abundant in IC 4997 than in the sun. IC 4997 presents puzzling problems.

  2. The Kinematics of the Permitted C ii λ 6578 Line in a Large Sample of Planetary Nebulae

    International Nuclear Information System (INIS)

    Richer, Michael G.; Suárez, Genaro; López, José Alberto; García Díaz, María Teresa

    2017-01-01

    We present spectroscopic observations of the C ii λ 6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ 6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ 6578 line are not those expected if this line arises from the recombination of C 2+ ions or the fluorescence of C + ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in H α line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.

  3. The Kinematics of the Permitted C ii λ 6578 Line in a Large Sample of Planetary Nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Richer, Michael G.; Suárez, Genaro; López, José Alberto; García Díaz, María Teresa, E-mail: richer@astrosen.unam.mx, E-mail: gsuarez@astro.unam.mx, E-mail: jal@astrosen.unam.mx, E-mail: tere@astro.unam.mx [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, Baja California (Mexico)

    2017-03-01

    We present spectroscopic observations of the C ii λ 6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ 6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ 6578 line are not those expected if this line arises from the recombination of C{sup 2+} ions or the fluorescence of C{sup +} ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in H α line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.

  4. Astrophysics of gaseous nebulae and active galactic nuclei

    International Nuclear Information System (INIS)

    Osterbrock, D.E.

    1989-01-01

    A graduate-level text and reference book on gaseous nebulae and the emission regions in Seyfert galaxies, quasars, and other types of active galactic nuclei (AGN) is presented. The topics discussed include: photoionization equilibrium, thermal equilibrium, calculation of emitted spectrum, comparison of theory with observations, internal dynamics of gaseous nebulae, interstellar dust, regions in the galactic context, planetary nebulae, nova and supernova remnants, diagnostics and physics of AGN, observational results on AGN

  5. Multiwavelength diagnostic properties of Galactic planetary nebulae detected by the GLIMPSE-I

    Science.gov (United States)

    Cohen, Martin; Parker, Quentin A.; Green, Anne J.; Miszalski, Brent; Frew, David; Murphy, Tara

    2011-05-01

    We uniformly analyse 136 optically detected planetary nebulae (PNe) and candidates from the GLIMPSE-I in order to develop robust, multiwavelength, classification criteria to augment existing diagnostics and provide pure PN samples. PNe represent powerful astrophysical probes. They are important dynamical tracers, key sources of interstellar medium chemical enrichment, windows into late stellar evolution and potent cosmological yardsticks. However, their utility depends on separating them unequivocally from the many nebular mimics which can strongly resemble bona fide PNe in traditional optical images and spectra. We merge new PNe from the carefully evaluated, homogeneous Macquarie-AAO-Strasbourg Hα PN Project (MASH-I) and MASH-II surveys, which offer a wider evolutionary range of PNe than hitherto available, with previously known PNe classified by SIMBAD. Mid-infrared (MIR) measurements vitally complement optical data because they reveal other physical processes and morphologies via fine-structure lines, molecular bands and dust. MIR colour-colour planes, optical emission-line ratios and radio fluxes show the unambiguous classification of PNe to be complex, requiring all available evidence. Statistical trends provide predictive value and we offer quantitative MIR criteria to determine whether an emission nebula is most likely to be a PN or one of the frequent contaminants such as compact H II regions or symbiotic systems. Prerequisites have been optical images and spectra, but MIR morphology, colours, environment and a candidate's MIR-to-radio flux ratio provide a more rigorous classification. Our ultimate goal is to recognize PNe using only MIR and radio characteristics, enabling us to trawl for PNe effectively even in heavily obscured regions of the Galaxy.

  6. Planetary Nebulae As A Laboratory For Molecular Hydrogen in the Early Universe

    Science.gov (United States)

    Sellgren, Kris; Bromm, Volker; Dinerstein, Harriet

    2008-03-01

    We propose to obtain Spitzer IRS observations of the mid-infrared rotational lines of H2 in planetary nebulae (PNe) with very hot central stars, T > 100,000 K. Our primary motivation is to investigate the excitation and cooling of H2 exposed to UV radiation near very hot stars, which can serve as a proxy for conditions in the early universe. Cosmological simulations show that the first stellar generation (Pop. III) had high masses, > 100 Msun, and hot photospheres. The UV radiation they produced and its effect on the thermal state of the ambient H2 is relevant to subsequent star formation because stellar masses are determined by accretion processes which depend on temperature, and the metal-free primordial gas cooled primarily through excited H2. Yet the effects of this radiative feedback are uncertain: for example, whether it triggers or suppresses further star formation, and the resultant characteristic masses of second generation stars, which are key to cosmic reionization. PNe with hot central stars may be the only place where we can study the relevant microphysics. We therefore propose to obtain Spitzer spectra of such nebulae, sampling regions with a range of gas densities and radiation field dilution factors. We will use the results to derive an improved H2 cooling function to be incorporated into state of the art cosmological models. Our targets have been previously observed in the near-infrared H2 lines, so we have confidence that the lower excitation rotational lines are detectable. Evidence already exists that in some PNe the excited rotational states are overpopulated relative to standard fluorescence models, and that this may be related to the presence of Lyman-continuum photons. The observations proposed here will enable us to verify and quantify this phenomenon, and improve our understanding of H2 excitation. Spitzer is the only facility at present - and for at least the next decade - which can accomplish these goals.

  7. Identification of Near-infrared [Se iii] and [Kr vi] Emission Lines in Planetary Nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Sterling, N. C.; Mashburn, A. L. [Department of Physics, University of West Georgia, 1601 Maple Street, Carrollton, GA 30118 (United States); Madonna, S.; García-Rojas, J.; Luridiana, V. [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Butler, K. [Institut für Astronomie und Astrophysik, Scheinerstr. 1, D-81679 München (Germany); Morisset, C. [Instituto de Astronomía, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20164, 04510 (Mexico); Roederer, I. U., E-mail: nsterlin@westga.edu, E-mail: awhite15@my.westga.edu, E-mail: vale@iaa.es, E-mail: smadonna@iac.es, E-mail: jogarcia@iac.es, E-mail: butler@usm.uni-muenchen.de, E-mail: chris.morisset@gmail.com, E-mail: iur@umich.edu [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States)

    2017-05-10

    We identify [Se iii] 1.0994 μ m in the planetary nebula (PN) NGC 5315 and [Kr vi] 1.2330 μ m in three PNe from spectra obtained with the Folded-Port InfraRed Echellette (FIRE) spectrometer on the 6.5 m Baade Telescope. Se and Kr are the two most widely detected neutron-capture elements in astrophysical nebulae, and can be enriched by s -process nucleosynthesis in PN progenitor stars. The detection of [Se iii] 1.0994 μ m is particularly valuable when paired with observations of [Se iv] 2.2864 μ m, as it can be used to improve the accuracy of nebular Se abundance determinations, and allows Se ionization correction factor (ICF) schemes to be empirically tested for the first time. We present new effective collision strength calculations for Se{sup 2+} and Kr{sup 5+}, which we use to compute ionic abundances. In NGC 5315, we find that the Se abundance computed from Se{sup 3+}/H{sup +} is lower than that determined with ICFs that incorporate Se{sup 2+}/H{sup +}. We compute new Kr ICFs that take Kr{sup 5+}/H{sup +} into account, by fitting correlations found in grids of Cloudy models between Kr ionic fractions and those of more abundant elements, and use these to derive Kr abundances in four PNe. Observations of [Se iii] and [Kr vi] in a larger sample of PNe, with a range of excitation levels, are needed to rigorously test the ICF prescriptions for Se and our new Kr ICFs.

  8. Faint planetary nebulae in the Magellanic Clouds - central star properties and nebular abundances for the Jacoby sample

    International Nuclear Information System (INIS)

    Henry, R.B.C.; Liebert, J.; Boroson, T.A.

    1989-01-01

    Forty-four of the LMC and SMC planetary nebulae contained in Jacoby's (1980) sample are studied. Spectrophotometric observations were used to infer the Stoy temperatures, luminosities, and radii of the central stars. For objects in which forbidden O III electron temperatures could be determined, the nebular abundances of He, N, O, and Ne were calculated and compared with values for giant H II regions for the relevant host galaxy. When the present abundance results were compared with previously published results for planetary nebulae in the LMC, SMC, and the Galaxy, a strong correlation was found for O/H versus Ne/H and strong anticorrelations were found for O/H versus forbidden O III temperature, and N/O versus O/H. 69 refs

  9. Spectrophotometry near the atmospheric cutoff of the strongest Bowen resonance fluorescence lines of O III in two planetary nebulae

    Science.gov (United States)

    O'Dell, C. R.; Opal, Chet B.

    1989-01-01

    Spectrophotometric results are presented for the stronger, well-resolved Bowen O III resonance fluorescence emission lines in the planetary nebulae 7027 and NGC 7662 down to and including the intrinsically strong line at 3133 A. These data are combined with results from the IUE atlas of spectra and similar results for the longer wavelength lines by Likkel and Aller (1986) to give the first full coverage of the Bowen lines. Good agreement is found with fluorescence theory for the primary cascade lines, except for the Likkel and Aller results. The efficiency of conversion of the exciting He II Ly-alpha into O III lines is determined, and values comparable to other planetary nebulae are found.

  10. High-resolution 8-13 micron imaging of the planetary nebulae BD + 30 deg 3639 and NGC 6572

    International Nuclear Information System (INIS)

    Hora, J.L.; Hoffmann, W.F.; Deutsch, L.K.; Fazio, G.G.

    1990-01-01

    High-resolution midinfrared images of the planetary nebulae BD + 30 deg 3639 and NGC 6572 are presented at 8.3, 8.7, 9.8, 11.2, and 12.4 microns. Analysis of the maps of BD + 30 deg 3639 supports a model in which the infrared emission originates from two spatially distinct components, one which is responsible for the continuum radiation at 8-12 microns and the other which produces the emission-line features. The NGC 6572 images provides evidence for a previously undetected 11.2 micron UIR emission feature. Comparison with radio continuum maps indicates that the distribution of dust is similar to the distribution of ionized gas in each nebula. Various models of source morphology are also investigated. The planetary nebulae DB + 30 deg 3639 and NGC 6572 can be modeled by an optically thin cylinder or a prolate ellipsoid with enhanced equatorial emission. These models reproduce well the general features of the nebula, such as the bipolar lobes of emission and the ring structure. 67 refs

  11. The halo of M 49 and its environment as traced by planetary nebulae populations

    Science.gov (United States)

    Hartke, J.; Arnaboldi, M.; Longobardi, A.; Gerhard, O.; Freeman, K. C.; Okamura, S.; Nakata, F.

    2017-07-01

    Context. The galaxy M 49 (NGC 4472) is the brightest early-type galaxy in the Virgo Cluster. It is located in subcluster B and has an unusually blue, metal-poor outer halo. Planetary nebulae (PNe) are excellent tracers of diffuse galaxy and intragroup light (IGL). Aims: We aim to present a photometric survey of PNe in the galaxy's extended halo to characterise its PN population, as well as the surrounding IGL of the subcluster B. Methods: PNe were identified based on their bright [OIII]5007 Å emission and absence of a broad-band continuum through automated detection techniques. Results: We identify 738 PNe out to a radius of 155 kpc from M 49's centre from which we define a complete sample of 624 PNe within a limiting magnitude of m5007,lim = 28.8. Comparing the PN number density to the broad-band stellar surface brightness profile, we find a variation of the PN-specific frequency (α-parameter) with radius. The outer halo beyond 60kpc has a 3.2 times higher α-parameter compared to the main galaxy halo (α2.5,innerM 49 = (3.20 ± 0.43) × 10-9 PN L-1⊙,bol), which is likely due to contribution from the surrounding blue IGL. We use the planetary nebulae luminosity function (PNLF) as an indicator of distance and stellar population. Its slope, which correlates empirically with galaxy type, varies within the inner halo. In the eastern quadrant of M 49, the PNLF slope is shallower, indicating an additional localised, bright PN population following an accretion event, likely that of the dwarf irregular galaxy VCC1249. We also determined a distance modulus of μPNLF = 31.29+ 0.07-0.08 for M 49, corresponding to a physical distance of 18.1 ± 0.6 Mpc, which agrees with a recent surface-brightness fluctuations distance. Conclusions: The PN populations in the outer halo of M 49 are consistent with the presence of a main Sérsic galaxy halo with a slight (B - V) colour gradient of 10-4 mag arcsec-1 surrounded by IGL with a very blue colour of (B - V) = 0.25 and a constant

  12. Water Fountains in the Sky: Streaming Water Jets from Aging Star Provide Clues to Planetary-Nebula Formation

    Science.gov (United States)

    2002-06-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have found that an aging star is spewing narrow, rotating streams of water molecules into space, like a jerking garden hose that has escaped its owner's grasp. The discovery may help resolve a longstanding mystery about how the stunningly beautiful objects called planetary nebulae are formed. Artist's Conception of W43A. Artist's conception of W43A, with the aging star surrounded by a disk of material and a precessing, twisted jet of molecules streaming away from it in two directions. Credit: Kirk Woellert/National Science Foundation. The astronomers used the VLBA, operated by the National Radio Astronomy Observatory, to study a star called W43A. W43A is about 8,500 light-years from Earth in the direction of the constellation Aquila, the eagle. This star has come to the end of its normal lifetime and, astronomers believe, is about to start forming a planetary nebula, a shell of brightly glowing gas lit by the hot ember into which the star will collapse. "A prime mystery about planetary nebulae is that many are not spherical even though the star from which they are ejected is a sphere," said Phillip Diamond, director of the MERLIN radio observatory at Jodrell Bank in England, and one of the researchers using the VLBA. "The spinning jets of water molecules we found coming from this star may be one mechanism for producing the structures seen in many planetary nebulae," he added. The research team, led by Hiroshi Imai of Japan's National Astronomical Observatory (now at the Joint Institute for VLBI in Europe, based in the Netherlands), also includes Kumiko Obara of the Mizusawa Astrogeodynamics Observatory and Kagoshima University; Toshihiro Omodaka, also of Kagoshima University; and Tetsuo Sasao of the Japanese National Astronomical Observatory. The scientists reported their findings in the June 20 issue of the scientific journal Nature. As stars similar to our Sun

  13. Central stars of planetary nebulae. II. New OB-type and emission-line stars

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.

    2011-07-01

    Context. There are more than 3000 confirmed and probably known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We have undertaken a spectroscopic survey of the central stars in PNe to identify their spectral types. Methods: We performed spectroscopic observations at low resolution with the 2-m telescope at CASLEO, Argentina. Results: We present the spectra of 46 central stars of PNe, most of them are OB-type and emission-line stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.The reduced spectra (FITS files) are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A172

  14. SPECTROSCOPIC OBSERVATIONS OF PLANETARY NEBULAE IN THE NORTHERN SPUR OF M31

    Energy Technology Data Exchange (ETDEWEB)

    Fang, X.; Liu, X.-W. [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zhang, Y. [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (China); Garcia-Benito, R. [Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Yuan, H.-B., E-mail: fangx@pku.edu.cn [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

    2013-09-10

    We present spectroscopy of three planetary nebulae (PNe) in the Northern Spur of the Andromeda galaxy (M31) obtained with the Double Spectrograph on the 5.1 m Hale Telescope at the Palomar Observatory. The samples were selected from the observations of Merrett et al. Our purpose is to investigate the formation of the substructures of M31 using PNe as a tracer of chemical abundances. The [O III] {lambda}4363 line is detected in the spectra of two objects, enabling temperature determinations. Ionic abundances are derived from the observed collisionally excited lines, and elemental abundances of nitrogen, oxygen, neon, sulfur, and argon are estimated. We study the correlations between oxygen and the {alpha}-element abundance ratios using our sample and the M31 disk and bulge PNe from the literature. In one of the three PNe, we observed a relatively higher oxygen abundance compared to the disk sample of M31 at similar galactocentric distances. The results of at least one of the three Northern Spur PNe might be in line with the proposed possible origin of the Northern Spur substructure of M31, i.e., the Northern Spur is connected to the Southern Stream and both substructures comprise the tidal debris of the satellite galaxies of M31.

  15. The Gaia Data Release 1 parallaxes and the distance scale of Galactic planetary nebulae

    Science.gov (United States)

    Stanghellini, Letizia; Bucciarelli, Beatrice; Lattanzi, Mario G.; Morbidelli, Roberto

    2017-11-01

    In this paper we gauge the potentiality of Gaia in the distance scale calibration of planetary nebulae (PNe) by assessing the impact of DR1 parallaxes of central stars of Galactic PNe (CSPNe) against known physical relations. For selected PNe targets with state-of-the-art data on angular sizes and fluxes, we derive the distance-dependent parameters of the classical distance scales, i.e., physical radii and ionized masses, from DR1 parallaxes; we propagate the uncertainties in the estimated quantities and evaluate their statistical properties in the presence of large relative parallax errors; we populate the statistical distance scale diagrams with this sample and discuss its significance in light of existing data and current calibrations. We glean from DR1 parallaxes 8 CSPNe with S/N> 1. We show that this set of potential calibrators doubles the number of extant trigonometric parallaxes (from HST and ground-based), and increases by two orders of magnitude the domain of physical parameters probed previously. We then use the combined sample of suitable trigonometric parallaxes to fit the physical-radius-to-surface-brightness relation. This distance scale calibration, although preliminary, appears solid on statistical grounds, and suggestive of new PNe physics. With the tenfold improvement in PNe number statistics and astrometric accuracy expected from future Gaia releases the new distance scale, already very intriguing, will be definitively constrained.

  16. The binary fraction of planetary nebula central stars - III. the promise of VPHAS+

    Science.gov (United States)

    Barker, Helen; Zijlstra, Albert; De Marco, Orsola; Frew, David J.; Drew, Janet E.; Corradi, Romano L. M.; Eislöffel, Jochen; Parker, Quentin A.

    2018-04-01

    The majority of planetary nebulae (PNe) are not spherical, and current single-star models cannot adequately explain all the morphologies we observe. This has led to the Binary Hypothesis, which states that PNe are preferentially formed by binary systems. This hypothesis can be corroborated or disproved by comparing the estimated binary fraction of all PNe central stars (CS) to that of the supposed progenitor population. One way to quantify the rate of CS binarity is to detect near infrared excess indicative of a low-mass main-sequence companion. In this paper, a sample of known PNe within data release 2 of the ongoing VPHAS+ is investigated. We give details of the method used to calibrate VPHAS+ photometry, and present the expected colours of CS and main-sequence stars within the survey. Objects were scrutinized to remove PN mimics from our sample and identify true CS. Within our final sample of seven CS, six had previously either not been identified or confirmed. We detected an i-band excess indicative of a low-mass companion star in three CS, including one known binary, leading us to conclude that VPHAS+ provides the precise photometry required for the IR excess method presented here, and will likely improve as the survey completes and the calibration process finalized. Given the promising results from this trial sample, the entire VPHAS+ catalogue should be used to study PNe and extend the IR excess-tested CS sample.

  17. Optical Spectra of Radio Planetary Nebulae in the Large Magellanic Cloud

    Directory of Open Access Journals (Sweden)

    Payne, J. L.

    2008-12-01

    Full Text Available We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe in the Large Magellanic Cloud (LMC. Originally found in Australia Telescope Compact Array (ATCA LMC surveys at 1.4, 4.8 and 8.64~GHz and confirmed by new high resolution ATCA images at 6 and 3~cm (4arcsec/2arcsec, these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC. Their spectra were obtained using the Radcliffe 1.9-meter telescope in Sutherland (South Africa. All of the optical PNe and radio candidates are within 2arcsec and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8~$M_odot$, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB phase or prior. We also identify a sub-population (33\\% of radio PNe candidates with prominent ionized iron emission lines.

  18. Optical spectra of radio planetary nebulae in the large Magellanic Cloud

    Directory of Open Access Journals (Sweden)

    Payne J.L.

    2008-01-01

    Full Text Available We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe in the Large Magellanic Cloud (LMC. Originally found in Australia Telescope Compact Array (ATCA LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (4' /2' , these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC. Their spectra were obtained using the Radcliff 1.9-meter telescope in Sutherland (South Africa. All of the optical PNe and radio candidates are within 2' and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 Mfi, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB phase or prior. We also identify a sub-population (33% of radio PNe candidates with prominent ionized iron emission lines.

  19. A Treasure Trove of Molecules: Uncovering the Molecular Content of Planetary Nebulae

    Science.gov (United States)

    Schmidt, Deborah Rose; Ziurys, Lucy M.

    2016-06-01

    We have undertaken a systematic study of the molecular content of planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). A search for HCN and HCO+ in seventeen PNe in which CO had previously been detected has been carried out. The J=1→0 and J=3→2 transitions of both molecules were searched for using the ARO 12-M Telescope and ARO Sub-Millimeter Telescope respectively. At least one transition of either molecule was detected in thirteen sources. Assuming a kinetic temperature of 20 K, the abundances of these two molecule, relative to H2, were determined to be f(HCN) ~ 0.1 - 9.1 × 10-7 and f(HCO+) ~ 0.04 - 7.4 × 10-7. The abundances of both species were found to remain relatively constant with nebular age, in contrast to predictions of chemical models. A subset of eleven of these PNe were subsequently searched for the J=1→0 and J=3→2 transitions of CCH and HNC. HNC was detected in ten sources, resulting in HCN/HNC ratios of ~2-6, while CCH has been detected in eight. The most current results for the abundances of both molecules will be reported. The correlation of CCH and C60 will also be presented. Establishing molecular abundances in PNe is vital to our understanding of their environments as well as the nature of their ejecta, which populate the interstellar medium (ISM).

  20. THE OUTFLOWS AND THREE-DIMENSIONAL STRUCTURE OF NGC 6337: A PLANETARY NEBULA WITH A CLOSE BINARY NUCLEUS

    International Nuclear Information System (INIS)

    Garcia-Diaz, Ma. T.; Clark, D. M.; Lopez, J. A.; Steffen, W.; Richer, M. G.

    2009-01-01

    NGC 6337 is a member of the rare group of planetary nebulae where a close binary nucleus has been identified. The nebula's morphology and emission line profiles are both unusual, particularly the latter. We present a thorough mapping of spatially resolved, long-slit echelle spectra obtained over the nebula that allows a detailed characterization of its complex kinematics. This information, together with narrowband imagery, is used to produce a three-dimensional (3D) model of the nebula using the code SHAPE. The 3D model yields a slowly expanding toroid with large density fluctuations in its periphery that are observed as cometary knots. A system of bipolar expanding caps of low ionization is located outside the toroid. In addition, an extended high velocity and tenuous bipolar collimated outflow is found emerging from the core and sharply bending in opposite directions, a behavior that cannot be accounted for by pure magnetic launching and collimation unless the source of the outflow is precessing or rotating, as could be expected from a close binary nucleus.

  1. Kinematic and chemical study of planetary nebulae and H II regions in NGC 3109

    Science.gov (United States)

    Flores-Durán, S. N.; Peña, M.; Ruiz, M. T.

    2017-05-01

    Aims: We present high-resolution spectroscopy of a number of planetary nebulae (PNe) and H II regions distributed along the dwarf irregular galaxy NGC 3109 and compare their kinematical behavior with that of H I data. We aim to determine if there is a kinematical connection among these objects. We also aim to determine the chemical composition of some PNe and H II regions in this galaxy and discuss it in comparison with stellar evolution models. Methods: Data for eight PNe and one H II region were obtained with the high-resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) at Las Campanas Observatory, Chile. Data for three PNe, six compact H II regions, and nine knots or clumps in extended H II regions were obtained with the high-resolution spectrograph Manchester Echelle Spectrometer (MES) attached to the 2.1m telescope at the Observatorio Astronómico Nacional, SPM, B.C., Mexico. An additional object was obtained from The SPM Catalogue of Extragalactic Planetary Nebulae. Thus, in total we have high-quality data for nine of the 20 PNe detected in this galaxy, and many H II regions. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 7.8 km s-1. Data for blue supergiant stars were collected from the literature to be included in the analysis. The heliocentric radial velocities of the different objects were compared to the velocities of the H I disk at the same position. Physical conditions and ionic abundances of PNe and H II regions were obtained from the emission lines, and we used recent ionization correction factors to derive the total chemical abundances. Results: From the analysis of radial velocities we found that H II regions in NGC 3109 share the kinematics of the H I disk at the same projected position with very low dispersion in velocities. Blue supergiant stars and PNe rotate in the same direction as the H I disk but these objects have much larger dispersion; this larger dispersion

  2. The structure of the planetary nebula NGC 2371 in the visible and mid-infrared

    Science.gov (United States)

    Ramos-Larios, Gerardo; Phillips, J. P.

    2012-09-01

    We investigate the structure of the planetary nebula NGC 2371 using [O III] λ5007 imaging taken with the Jacobus Kapteyn 1.0 m telescope, and [N II] λ6584, [O III] λ5007 and Hα results acquired with the Hubble Space Telescope. These are supplemented with archival mid-infrared (MIR) observations taken with the Spitzer Space Telescope. We note the presence of off-axis low-ionization spokes along a position angle of 65°, and associated collars of enhanced [O III] emission. The spokes appear to consist of dense condensations having low-excitation tails, possibly arising due to ultraviolet shadowing and/or ram-pressure stripping of material. Line ratios imply that most of the emission arises through photoionization, and is unlikely to derive from post-shock cooling regions. An analysis of these features in the MIR suggests that they may also be associated with high levels of emission from polycyclic aromatic hydrocarbons (PAHs), together with various permitted and forbidden line transitions. Such high levels of PAH emission, where they are confirmed, may develop as a result of preferentially enhanced far-ultraviolet pumping of the molecules, or shattering of larger grains within local shocks. Although H2 emission may also contribute to these trends, it is argued that shock-excited transitions would lead to markedly differing results. We finally note that thin filaments and ridges of [O III] emission may indicate the presence of shock activity at the limits of the interior envelope, as well as at various positions within the shell itself. We also note that radially increasing fluxes at 3.6, 5.8 and 8.0 μm, relative to the emission at 4.5 μm, may arise due to enhanced PAH emission in external photodissociative regions.

  3. THE FIRST ''WATER FOUNTAIN'' COLLIMATED OUTFLOW IN A PLANETARY NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, José F.; Miranda, Luis F.; Guerrero, Martín A. [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Suárez, Olga; Bendjoya, Philippe; Lagadec, Eric [Laboratoire Lagrange, UMR 7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06304 Nice (France); Rizzo, J. Ricardo; García-García, Enrique [Centro de Astrobiología (INTA-CSIC), Ctra. M-108, km. 4, E-28850 Torrejón de Ardoz (Spain); Green, James A. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Uscanga, Lucero [Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Athens (Greece); Ramos-Larios, Gerardo [Instituto de Astronomía y Meteorología, Av. Vallarta No. 2602, Col. Arcos Vallarta, C.P. 44130 Guadalajara, Jalisco (Mexico)

    2015-02-01

    ''Water fountains'' (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-asymptotic giant branch (post-AGB) and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103–5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103–5754 is an evolved object, while the mid-IR spectrum displays unambiguous [Ne II] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range (≅ 75 km s{sup –1}) and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and kinematical distribution of the maser emission in this object are significantly different from those in other WFs. Moreover, the velocity distribution of the maser emission shows a ''Hubble-like'' flow (higher velocities at larger distances from the central star), consistent with a short-lived, explosive mass-loss event. This velocity pattern is not seen in other WFs (which are presumably in earlier evolutionary stages). We therefore suggest that we are witnessing a fundamental change of mass-loss processes in WFs, with water masers being pumped by steady jets in post-AGB stars, but tracing explosive/ballistic events as the object enters the PN phase.

  4. DETECTION OF DIFFUSE X-RAY EMISSION FROM PLANETARY NEBULAE WITH NEBULAR O VI

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, N.; Guerrero, M. A. [Instituto de Astrofisica de Andalucia, IAA-CSIC, c/ Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Chu, Y.-H.; Gruendl, R. A. [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Jacob, R.; Schoenberner, D.; Steffen, M., E-mail: nieves@iaa.es [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2013-04-10

    The presence of O VI ions can be indicative of plasma temperatures of a few Multiplication-Sign 10{sup 5} K that are expected in heat conduction layers between the hot shocked stellar wind gas at several 10{sup 6} K and the cooler (10{sup 4} K) nebular gas of planetary nebulae (PNe). We have used FUSE observations of PNe to search for nebular O VI emission or absorption as a diagnostic of the conduction layer to ensure the presence of hot interior gas. Three PNe showing nebular O VI, namely IC 418, NGC 2392, and NGC 6826, have been selected for Chandra observations and diffuse X-ray emission is indeed detected in each of these PNe. Among the three, NGC 2392 has peculiarly high diffuse X-ray luminosity and plasma temperature compared with those expected from its stellar wind's mechanical luminosity and terminal velocity. The limited effects of heat conduction on the plasma temperature of a hot bubble at the low terminal velocity of the stellar wind of NGC 2392 may partially account for its high plasma temperature, but the high X-ray luminosity needs to be powered by processes other than the observed stellar wind, probably the presence of an unseen binary companion of the central star of the PN (CSPN) of NGC 2392. We have compiled relevant information on the X-ray, stellar, and nebular properties of PNe with a bubble morphology and found that the expectations of bubble models including heat conduction compare favorably with the present X-ray observations of hot bubbles around H-rich CSPNe, but have notable discrepancies for those around H-poor [WR] CSPNe. We note that PNe with more massive central stars can produce hotter plasma and higher X-ray surface brightness inside central hot bubbles.

  5. Pushing the limits: detecting H2 emission from faint bipolar planetary nebulae in the IPHAS sample

    Science.gov (United States)

    Ramos-Larios, G.; Guerrero, M. A.; Sabin, L.; Santamaría, E.

    2017-09-01

    We have obtained deep narrowband images in the near-infrared H2 λ2.122 μm emission line for a sample of 15 faint Isaac Newton Telescope Photometric H α Survey (IPHAS) bipolar planetary nebulae (PNe) to search for molecular material. H2 emission is found in most of them (14 out of 15), mostly associated with rings at their equatorial regions and with their bipolar lobes. These detections add to the high occurrence of H2 emission among bipolar PNe reported in previous works, resulting from the large reservoir of molecular material in these sources and the suitable excitation conditions for H2 emission. The correlation between detailed bipolar morphology and H2 luminosity is also confirmed: bipolar PNe with broad equatorial rings (R-BPNe) have almost no continuum emission, are H2 brighter and have larger H2/Br γ line ratio than bipolar PNe with pinched equatorial waists (W-BPNe). The origin of this dichotomy is unclear. The larger size and age of R-BPNe are consistent with shock excitation of H2, whereas ultraviolet pumping is most likely the excitation mechanism in the smaller and younger W-BPNe, which would explain their lower H2 luminosity. Although both types of bipolar PNe seem to proceed from the same progenitor population, this does not imply that R-BPNe descend from W-BPNe. Otherwise, we note that some of the H2-weak bipolar PNe harbor post-common envelope binary systems and symbiotic stars. Finally, we suggest that the long-living H2 emission from R-BPNe arises from a discrete distribution of compact knots embedded within the ionized gas at the equatorial region.

  6. Planetary nebulae search in the outskirts of M33: looking for the farthest candidates

    Science.gov (United States)

    Galera Rosillo, Rebeca; Corradi, Romano L. M.; Mampaso Recio, Antonio

    2015-08-01

    The nearby disc galaxy M33 is one of the best laboratories for testing chemical evolution models in galaxies and for understanding disc formation mechanisms. In this galaxy, planetary nebulae (PNe) were previously extensively studied only within a galactocentric radius of 8 kpc.In the framework of a broad study of the population of PNe in Local Group disc galaxies, we present the results of a deep narrow-band imaging of the outer regions of M33, performed using the Wide Field Camera at the 2.5 m Isaac Newton Telescope (INT).The INT images were obtained in the narrow-band filters selecting the [OIII] 5007 Å and Hα 6563 Å lines, plus broad-band filters SDSS g and i. A photometric catalog of around 150000 sources covering a total area of 5 square degrees, and extending out to 2 deg (30 kpc at the adopted distance of 840 kpc) from the centre of the galaxy is presented.PNe candidates are selected in the [OIII]-g vs Hα-r colour-colour diagram as bright emitters in the narrowband filters. A number of candidates with similar colours to those of known PNe, and with an apparent [OIII] magnitude > 21 have been selected for future follow-up. Three of these have been already spectroscopically confirmed at the William Herschel Telescope (WHT).Our survey will improve the knowledge of the PNe population in the outskirts of M33, constraining the properties of its metal-poor halo and of the extended disc substructures that have been proposed to be related to a relatively recent interaction with M31.

  7. Variability in Proto-planetary Nebulae. I. Light Curve Studies of 12 Carbon-rich Objects

    Science.gov (United States)

    Hrivnak, Bruce J.; Lu, Wenxian; Maupin, Richard E.; Spitzbart, Bradley D.

    2010-02-01

    We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of ~150 days for the coolest (G8) to 35-40 days for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-asymptotic giant branch (post-AGB) star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200 K), detached dust shells and published models imply that intensive mass loss ended 400-2000 years ago. The detection of periods as long as 150 days in these requires a revision in the published post-AGB evolution models that couple the pulsation period to the mass loss rate and that assume that intensive mass loss ended when the pulsation period had decreased to 100 days. This revision will have the effect of extending the timescale for the early phases of post-AGB evolution. It appears that real time evolution in the pulsation periods of individual objects may be detectable on the timescale of two or three decades.

  8. A deep narrowband survey for planetary nebulae at the outskirts of M 33

    Science.gov (United States)

    Galera-Rosillo, R.; Corradi, R. L. M.; Mampaso, A.

    2018-04-01

    Context. Planetary nebulae (PNe) are excellent tracers of stellar populations with low surface brightness, and therefore provide a powerful method to detect and explore the rich system of substructures discovered around the main spiral galaxies of the local group. Aim. We searched the outskirts of the local group spiral galaxy M 33 (the Triangulum) for PNe to gain new insights into the extended stellar substructure on the northern side of the disc and to study the existence of a faint classical halo. Methods: The search is based on wide field imaging covering a 4.5 square degree area out to a maximum projected distance of about 40 kpc from the centre of the galaxy. The PN candidates are detected by the combination of images obtained in narrowband filters selecting the [OIII]λ5007 Å and Hα + [NII] nebular lines and in the continuum g' and r' broadband filters. Results: Inside the bright optical disc of M 33, eight new PN candidates were identified, three of which were spectroscopically confirmed. No PN candidates were found outside the limits of the disc. Fourteen additional sources showing [OIII] excess were also discovered. Conclusions: The absence of bright PN candidates in the area outside the galaxy disc covered by this survey sets an upper limit to the luminosity of the underlying population of 1.6 × 107 L⊙, suggesting the lack of a massive classical halo, which is in agreement with the results obtained using the red giant branch population. Based on observations made with the Isaac Newton Telescope and service observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  9. ROTATING STARS AND THE FORMATION OF BIPOLAR PLANETARY NEBULAE. II. TIDAL SPIN-UP

    Energy Technology Data Exchange (ETDEWEB)

    García-Segura, G. [Instituto de Astronomía, Universidad Nacional Autónoma de Mexico, Km. 103 Carr. Tijuana-Ensenada, 22860, Ensenada, B. C. (Mexico); Villaver, E. [Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Manchado, A. [Instituto de Astrofísica de Canarias, Via Láctea s/n, E-38200 La Laguna, Tenerife (Spain); Langer, N. [Argelander-Institut für Astronomie, Universität Bonn, D-53121 Bonn (Germany); Yoon, S.-C., E-mail: ggs@astrosen.unam.mx [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul, 151-747 (Korea, Republic of)

    2016-06-01

    We present new binary stellar evolution models that include the effects of tidal forces, rotation, and magnetic torques with the goal of testing planetary nebulae (PNs) shaping via binary interaction. We explore whether tidal interaction with a companion can spin-up the asymptotic giant brach (AGB) envelope. To do so, we have selected binary systems with main-sequence masses of 2.5 M {sub ⊙} and 0.8 M {sub ⊙} and evolve them allowing initial separations of 5, 6, 7, and 8 au. The binary stellar evolution models have been computed all the way to the PNs formation phase or until Roche lobe overflow (RLOF) is reached, whatever happens first. We show that with initial separations of 7 and 8 au, the binary avoids entering into RLOF, and the AGB star reaches moderate rotational velocities at the surface (∼3.5 and ∼2 km s{sup −1}, respectively) during the inter-pulse phases, but after the thermal pulses it drops to a final rotational velocity of only ∼0.03 km s{sup −1}. For the closest binary separations explored, 5 and 6 au, the AGB star reaches rotational velocities of ∼6 and ∼4 km s{sup −1}, respectively, when the RLOF is initiated. We conclude that the detached binary models that avoid entering the RLOF phase during the AGB will not shape bipolar PNs, since the acquired angular momentum is lost via the wind during the last two thermal pulses. This study rules out tidal spin-up in non-contact binaries as a sufficient condition to form bipolar PNs.

  10. Abundances of Planetary Nebulae IC 418, IC 2165 and NGC 5882

    NARCIS (Netherlands)

    Pottasch, [No Value; Bernard-Salas, J; Beintema, DA; Feibelman, WA

    The ISO and IUE spectra of the elliptical nebulae NGC 5882, IC 418 and IC 2165 are presented. These spectra are combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to

  11. The gas turbulence in planetary nebulae: quantification and multi-D maps from long-slit, wide-spectral range echellogram

    OpenAIRE

    Sabbadin, F.; Turatto, M.; Benetti, S.; Ragazzoni, R.; Cappellaro, E.

    2008-01-01

    This methodological paper is part of a short series dedicated to the long-standing astronomical problem of de-projecting the bi-dimensional, apparent morphology of a three-dimensional distribution of gas. We focus on the quantification and spatial recovery of turbulent motions in planetary nebulae (and other classes of expanding nebulae) by means of long-slit echellograms over a wide spectral range. We introduce some basic theoretical notions, discuss the observational methodology, and develo...

  12. FARADAY ROTATION IN THE TAIL OF THE PLANETARY NEBULA DeHt 5

    International Nuclear Information System (INIS)

    Ransom, R. R.; Kothes, R.; Wolleben, M.; Landecker, T. L.

    2010-01-01

    We present 1420 MHz polarization images of a 5 0 x 5 0 region around the planetary nebula (PN) DeHt 5. The images reveal narrow Faraday-rotation structures on the visible disk of DeHt 5, as well as two wider, tail-like, structures 'behind' DeHt 5. Though DeHt 5 is an old PN known to be interacting with the interstellar medium (ISM), a tail has not previously been identified for this object. The innermost tail is ∼3 pc long and runs away from the northeast edge of DeHt 5 in a direction roughly opposite that of the sky-projected space velocity of the white dwarf central star, WD 2218+706. We believe this tail to be the signature of ionized material ram-pressure stripped and deposited downstream during a >74,000 yr interaction between DeHt 5 and the ISM. We estimate the rotation measure (RM) through the inner tail to be -15 ± 5 rad m -2 , and, using a realistic estimate for the line-of-sight component of the ISM magnetic field around DeHt 5, derive an electron density in the inner tail of n e = 3.6 ± 1.8 cm -3 . Assuming the material is fully ionized, we estimate a total mass in the inner tail of 0.68 ± 0.33 M sun and predict that 0.49 ± 0.33 M sun was added during the PN-ISM interaction. The outermost tail consists of a series of three roughly circular components, which have a collective length of ∼11.0 pc. This tail is less conspicuous than the inner tail and may be the signature of the earlier interaction between the WD 2218+706 asymptotic giant branch (AGB) progenitor and the ISM. The results for the inner and outer tails are consistent with hydrodynamic simulations and may have implications for the PN missing-mass problem as well as for models which describe the impact of the deaths of intermediate-mass stars on the ISM.

  13. New high (> or =6M/sub sun/) upper mass limit for planetary nebula formation, and a new high lower mass bound for carbon detonation supernova models

    International Nuclear Information System (INIS)

    Tuchman, Y.; Sack, N.; Barkat, Z.

    1978-01-01

    Envelope ejection leading to a planetary nebula has been recently shown to occur as the terminal point of the Mira stage. The ejection is due to a diverging pulsational instability, not to a dynamical one. It is found that in this case (and for Population I, mixing length=1 pressure scale height) the upper mass limit for formation of planetary nebulae is at least 6 M/sub sun/. It thus follows that the lower mass limit for realization of carbon detonation model configurations is also at last 6 M/sub sun/

  14. C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines

    Science.gov (United States)

    García-Rojas, J.; Delgado-Inglada, G.; García-Hernández, D. A.; Dell'Agli, F.; Lugaro, M.; Karakas, A. I.; Rodríguez, M.

    2018-02-01

    We present deep high-resolution (R ˜ 15 000) and high-quality UVES optical spectrophotometry of nine planetary nebulae with dual-dust chemistry. We compute physical conditions from several diagnostics. Ionic abundances for a large number of ions of N, O, Ne, S, Cl, Ar, K, Fe and Kr are derived from collisionally excited lines. Elemental abundances are computed using state-of-the-art ionization correction factors. We derive accurate C/O ratios from optical recombination lines. We have re-analysed additional high-quality spectra of 14 PNe from the literature following the same methodology. Comparison with asymptotic giant branch models reveals that about half of the total sample objects are consistent with being descendants of low-mass progenitor stars (M 3-4 M⊙) that have suffered a mild hot bottom burning. None of the objects seem to be descendant of very massive progenitors. We propose that in most of the planetary nebulae studied here, the polycyclic aromatic hydrocarbons have been formed through the dissociation of the CO molecule. The hypothesis of a last thermal pulse that turns O-rich PNe into C-rich PNe is discarded, except in three objects, that show C/O > 1. We also discuss the possibility of an He pre-enrichment to explain the most He-enriched objects. We cannot discard another scenarios like extra mixing, stellar rotation or binary interactions to explain the chemical abundances behaviour observed in our sample.

  15. A Renewed Look at the Planetary Nebula Luminosity Function: Circumstellar Extinction and Contamination From Compact Supernova Remnants

    Science.gov (United States)

    Davis, Brian; Ciardullo, Robin; Feldmeier, John; Jacoby, George H.; McCarron, Adam; Herrmann, Kimberly

    2018-01-01

    The planetary nebula luminosity function (PNLF) has been used as an extragalactic distance indicator since 1988, but there are still unsolved problems associated with its use. The two most serious involve PNLF distances beyond ~ 10 Mpc, which tend to be slightly smaller than those of other methods, and the lack of a theoretical explanation for the technique. We investigate these questions using a combination of narrow-band imaging data from the KPNO 4-m telescope, and recent LRS2 spectroscopy from the Hobby-Eberly Telescope.For the first project, we consider the implications of spectroscopic investigations by Kreckel et al. (2017), who found that in M74, several of the brightest planetary nebula (PN) candidates found by Herrmann et al. (2008) are actually compact supernova remnants (SNRs). First, we measure the [O III] and H-alpha fluxes of all the known SNRs in M31 and M33, and test whether those objects could be misidentified as bright PNe at distances beyond ~ 8 Mpc. We also obtain spectroscopy of bright PN candidates in the Fireworks Galaxy, NGC 6946, to test for PN/SNR confusion via the strengths of the [N II] and [S II] emission lines. Both experiments suggest that compact supernova remnants are not an important source of contamination in photometric surveys for extragalactic PNe.For the second project, we, for the first time, determine the de-reddened PNLF of an old stellar population. By performing spectroscopy of the brightest PN in M31’s bulge and measuring the objects’ Balmer decrements, we remove the effects of circumstellar extinction and derive the true location of the PNLF’s bright-end cutoff. In future studies, these data can be used to directly test the latest PNLF models, which combine modern post-AGB stellar evolutionary tracks with the physics of expanding nebulae.

  16. COMPACT GALACTIC PLANETARY NEBULAE: AN HST /WFC3 MORPHOLOGICAL CATALOG, AND A STUDY OF THEIR ROLE IN THE GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Stanghellini, Letizia; Shaw, Richard A. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Villaver, Eva [Universidad Autónoma de Madrid, Departamento de Física Teórica C-XI, E-28049 Madrid (Spain)

    2016-10-10

    We present the images of a Hubble Space Telescope ( HST /WFC3) snapshot program of angularly compact Galactic planetary nebulae (PNe), acquired with the aim of studying their size, evolutionary status, and morphology. PNe that are smaller than ∼4″ are underrepresented in most morphological studies, and today they are less well studied than their immediate evolutionary predecessors, the pre-planetary nebulae. The images have been acquired in the light of [O iii] λ 5007, which is commonly used to classify the PN morphology, in the UV continuum with the aim of detecting the central star unambiguously, and in the I -band to detect a cool stellar companion, if present. The sample of 51 confirmed PNe exhibits nearly the full range of primary morphological classes, with the distribution more heavily weighted toward bipolar PNe, but with the total of aspherical PNe almost identical to that of the general Galactic sample. A large range of microstructures is evident in our sample as well, with many nebulae displaying attached shells, halos, ansae, and internal structure in the form of arcs, rings, and spirals. Various aspherical structures in a few PNe, including detached arcs, suggest an interaction with the ISM. We studied the observed sample of compact Galactic PNe in the context of the general Galactic PN population, and explore whether their physical size, spatial distribution, reddening, radial metallicity gradient, and possible progenitors are peculiar within the population of Galactic PNe. We found that these compact Galactic PNe, which have been selected based on apparent dimensions, constitute a diverse Galactic PN population that is relatively uniformly distributed across the Galactic disk, including the outskirts of our Galaxy. This unique sample will be used in the future to probe the old Galactic disk population.

  17. A DETAILED MORPHO-KINEMATIC MODEL OF THE ESKIMO, NGC 2392: A UNIFYING VIEW WITH THE CAT'S EYE AND SATURN PLANETARY NEBULAE

    International Nuclear Information System (INIS)

    García-Díaz, Ma. T.; López, J. A.; Steffen, W.; Richer, M. G.

    2012-01-01

    The three-dimensional and kinematic structure of the Eskimo nebula, NGC 2392, has been notoriously difficult to interpret in detail given its complex morphology, multiple kinematic components and its nearly pole-on orientation along the line of sight. We present a comprehensive, spatially resolved, high-resolution, long-slit spectroscopic mapping of the Eskimo planetary nebula. The data consist of 21 spatially resolved, long-slit echelle spectra tightly spaced over the Eskimo and along its bipolar jets. This data set allows us to construct a velocity-resolved [N II] channel map of the nebula with a resolution of 10 km s –1 that disentangles its different kinematic components. The spectroscopic information is combined with Hubble Space Telescope images to construct a detailed three-dimensional morpho-kinematic model of the Eskimo using the code SHAPE. With this model we demonstrate that the Eskimo is a close analog to the Saturn and the Cat's Eye nebulae, but rotated 90° to the line of sight. Furthermore, we show that the main characteristics of our model apply to the general properties of the group of elliptical planetary nebulae with ansae or FLIERS, once the orientation is considered. We conclude that this kind of nebula belongs to a class with a complex common evolutionary sequence of events.

  18. Automatic Generation of Algorithms for the Statistical Analysis of Planetary Nebulae Images

    Science.gov (United States)

    Fischer, Bernd

    2004-01-01

    which use numerical approximations even in cases where closed-form solutions exist. AutoBayes is implemented in Prolog and comprises approximately 75.000 lines of code. In this paper, we take one typical scientific data analysis problem-analyzing planetary nebulae images taken by the Hubble Space Telescope-and show how AutoBayes can be used to automate the implementation of the necessary anal- ysis programs. We initially follow the analysis described by Knuth and Hajian [KHO2] and use AutoBayes to derive code for the published models. We show the details of the code derivation process, including the symbolic computations and automatic integration of library procedures, and compare the results of the automatically generated and manually implemented code. We then go beyond the original analysis and use AutoBayes to derive code for a simple image segmentation procedure based on a mixture model which can be used to automate a manual preproceesing step. Finally, we combine the original approach with the simple segmentation which yields a more detailed analysis. This also demonstrates that AutoBayes makes it easy to combine different aspects of data analysis.

  19. A search for photometric and spectroscopic evolutionary changes in the young planetary nebula Vy 2-2

    Science.gov (United States)

    Arkhipova, V. P.; Burlak, M. A.; Esipov, V. F.; Ikonnikova, N. P.; Komissarova, G. V.

    2017-12-01

    The results of long-term photometric and spectroscopic observations of the young compact planetary nebula Vy 2-2 (PNG 045.4-02.7) are presented. The UBV photometry in 1990-2016 has revealed a slight brightness trend in the yearly averaged data, most pronounced in the V band. We have measured the relative fluxes of optical emission lines on the spectrograms taken with the 1.25-m telescope at the Southern Station of the SAI MSU in 1999-2016, estimated the absolute flux in the Hβ line to be F(H β) = (2.1 ± 0.4) × 10-12 erg cm-2 s-1, and determined the interstellar extinction constant c(Hβ) = 1.8. The electron temperature and density in the nebula have been estimated from diagnostic line ratios: Te = (10-12) × 103 K and Ne ≥ 105 cm-3. To detect any possible evolutionary changes, we have compared the new observations with the archival data obtained over the entire history of spectroscopic observations of Vy 2-2. No significant changes in the relative intensities of the strongest emission lines and the integrated flux in the H β line exceeding the observational errors have been found. We have revealed a tendency for the intensity ratio F(λ4363)/F(λ4959) to decrease with time, which may be related to a decrease in the electron density in the nebula. Based on our photometric and spectroscopic data, we have estimated the luminosity of the central star of Vy 2-2, which corresponds to the evolutionary tracks for the most massive post-AGB stars of the O-rich sequence.

  20. Emission Line Galaxies Behind the Planetary Nebula IC 5148: Potential for a Serendipity Survey with Archival Data

    Science.gov (United States)

    Kimeswenger, S.; Barria, D.; Kausch, W.; Goldman, D. S.

    2018-04-01

    During the start of a survey program using FORS2 long slit spectroscopy on planetary nebulae (PN) and their haloes, we serendipitously discovered six background emission line galaxies (ELG) with redshifts of z = 0.2057, 0.3137, 0.37281, 0.4939, 0.7424 and 0.8668. Thus they clearly do not belong to a common cluster structure. We derived the major physical properties of the targets. Since the used long slit covers a sky area of only 570 arcsec2 (= 4.3×10-5 square degrees), we discuss further potential of serendipitous discoveries in archival data, beside the deep systematic work of the ongoing and upcoming big surveys. We conclude that archival data provide a decent potential for extending the overall data on ELGs without any selection bias.

  1. Central star temperatures of optically thick planetary nebulae and a distance-independent test of dredge-up theory

    Energy Technology Data Exchange (ETDEWEB)

    Kaler, J.B.; Jacoby, G.H. (Illinois Univ., Urbana (USA) Kitt Peak National Observatory, Tucson, AZ (USA))

    1989-10-01

    The effective temperatures are calculated and the V magnitudes are predicted for the central stars of 62 optically thick planetary nebulas by forcing agreement between the hydrogen and ionized helium Zanstra temperatures. Comparison to the measured V for 34 of the stars shows good agreement and validates the method for the other 28, for which no Zanstra analysis is available. In many cases the predicted V magnitudes are actually likely to be better than the currently measured values. The comparison suggests that optical depth and not an ultraviolet excess is the dominant cause of the Zanstra discrepancy. Nebular N/O correlates positively with effective temperature, demonstrating that the N/O-core mass relation rises more steeply than predicted by dredge-up theory. 77 refs.

  2. VARIABILITY IN PROTO-PLANETARY NEBULAE. III. LIGHT CURVE STUDIES OF MAGELLANIC CLOUD CARBON-RICH OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    Hrivnak, Bruce J.; Lu, Wenxian [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States); Volk, Kevin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); Szczerba, Ryszard; Hajduk, Marcin [N. Copernicus Astronomy Center, Rabianska 8, 87-100 Torun (Poland); Soszyński, Igor, E-mail: bruce.hrivnak@valpo.edu, E-mail: wen.lu@valpo.edu [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland)

    2015-05-20

    We have investigated the light variability in a sample of 22 carbon-rich post-AGB stars in the LMC and SMC, based primarily on photometric data from the Optical Gravitational Lensing Experiment survey. All are found to vary. Dominant periods are found in eight of them; these periods range from 49 to 157 days, and most of these stars have F spectral types. These eight are found to be similar to the Milky Way Galaxy (MWG) carbon-rich proto-planetary nebulae (PPNs) in several ways: (a) they are in the same period range of ∼38 to ∼160 days, (b) they have similar spectral types, (c) they are (all but one) redder when fainter, (d) they have multiple periods, closely spaced in time, with an average ratio of secondary to primary period of ∼1.0, and as an ensemble, (e) they show a trend of decreasing period with increasing temperature, and (f) they show a trend of decreasing amplitude with decreasing period. However, they possibly differ in that the decreasing trend of period with temperature may be slightly offset from that of the MWG. These eight are classified as PPNs. The other 14 all show evidence of variability on shorter timescales. They are likely hotter PPNs or young planetary nebulae. However, in the MWG the numbers of PPNs peak in the F−G spectral types, while it appears that in the LMC they peak at a hotter B spectral type. One of the periodic ones shows a small, R Coronae Borealis type light curve drop.

  3. Theory of extended stellar atmospheres. II. A grid of static spherical models for O stars and planetary nebula nuclei

    International Nuclear Information System (INIS)

    Kunasz, P.B.; Hummer, D.G.; Mihalas, D.

    1975-01-01

    Spherical static non-LTE model atmospheres are presented for stars with M/M/sub sun/=30 and 60 at various points on their evolutionary tracks, and for some nuclei of planetary nebulae at two points of a modified Harman-Seaton sequence. The method of Mihalas and Hummer was employed, which uses a parametrized radiation force multiplier to simulate the force of radiation arising from the entire line spectrum. However, in the present work the density structure computed in the LTE models was held fixed in the calculation of the corresponding non-LTE models; in addition, the opacity of an ''average light ion'' was taken into account. The temperatures for the non-LTE models are generally lower, at a given depth, than for the corresponding LTE models when T/sub eff/<45,000 K, while the situation is reversed at higher temperatures. The continuous energy distributions are generally flattened by extension. The Lyman jump is in emission for extended models of massive stars, but never for the models of nuclei of planetary nebulae (this is primarily a temperature effect). The Balmer jumps are always in absorption. The Lyman lines are in emission, and the Balmer lines in absorption; He ii lambda4686 comes into emission in the most extended models without hydrogen line pumping, showing that it is an indicator of atmospheric extension. Very severe limb darkening is found for extended models, which have apparent angular sized significantly smaller than expected from the geometrical size of the star. Extensive tables are given of monochromatic magnitudes, continuum jumps and gradients, Stomgren-system colors, monochromatic extensions, and the profiles and equivalent widths of the hydrogen lines for all models, and of the He ii lines for some of the 60 M/sub X/ models

  4. SULFURIZATION OF IRON IN THE DYNAMIC SOLAR NEBULA AND IMPLICATIONS FOR PLANETARY COMPOSITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ciesla, Fred J., E-mail: fciesla@uchicago.edu [Department of the Geophysical Sciences, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

    2015-02-10

    One explanation for the enhanced ratio of volatiles to hydrogen in Jupiter’s atmosphere compared to a a gas of solar composition is that the planet accreted volatile-bearing clathrates during its formation. Models, however, suggest that S would be over abundant if clathrates were the primary carrier of Jupiter’s volatiles. This led to the suggestion that S was depleted in the outer nebula due to the formation troilite (FeS). Here, this depletion is quantitatively explored by modeling the coupled dynamical and chemical evolution of Fe grains in the solar nebula. It is found that disks that undergo rapid radial expansion from an initially compact state may allow sufficient production of FeS and carry H{sub 2}S-depleted gas outward where ices would form, providing the conditions needed for S-depleted clathrates to form. However, this expansion would also carry FeS grains to this region, which could also be incorporated into planetesimals. Thus for clathrates to be a viable source of volatiles, models must account for the presence of both H{sub 2}S in FeS in the outer solar nebula.

  5. Nebulae and interstellar matter

    International Nuclear Information System (INIS)

    1987-01-01

    The South African Astronomical Observatory (SAAO) has investigated the IRAS source 1912+172. This source appears to be a young planetary nebula with a binary central star. During 1986 SAAO has also studied the following: hydrogen deficient planetary nebulae; high speed flows in HII regions, and the wavelength dependence of interstellar polarization. 2 figs

  6. The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781.

    Science.gov (United States)

    Otsuka, Masaaki; Ueta, Toshiya; van Hoof, Peter A M; Sahai, Raghvendra; Aleman, Isabel; Zijlstra, Albert A; Chu, You-Hua; Villaver, Eva; Leal-Ferreira, Marcelo L; Kastner, Joel; Szczerba, Ryszard; Exter, Katrina M

    2017-08-01

    We perform a comprehensive analysis of the planetary nebula (PN) NGC 6781 to investigate the physical conditions of each of its ionized, atomic, and molecular gas and dust components and the object's evolution, based on panchromatic observational data ranging from UV to radio. Empirical nebular elemental abundances, compared with theoretical predictions via nucleosynthesis models of asymptotic giant branch (AGB) stars, indicate that the progenitor is a solar-metallicity, 2.25-3.0 M ⊙ initial-mass star. We derive the best-fit distance of 0.46 kpc by fitting the stellar luminosity (as a function of the distance and effective temperature of the central star) with the adopted post-AGB evolutionary tracks. Our excitation energy diagram analysis indicates high-excitation temperatures in the photodissociation region (PDR) beyond the ionized part of the nebula, suggesting extra heating by shock interactions between the slow AGB wind and the fast PN wind. Through iterative fitting using the Cloudy code with empirically derived constraints, we find the best-fit dusty photoionization model of the object that would inclusively reproduce all of the adopted panchromatic observational data. The estimated total gas mass (0.41 M ⊙ ) corresponds to the mass ejected during the last AGB thermal pulse event predicted for a 2.5 M ⊙ initial-mass star. A significant fraction of the total mass (about 70%) is found to exist in the PDR, demonstrating the critical importance of the PDR in PNe that are generally recognized as the hallmark of ionized/H + regions.

  7. The interaction of the halo around the butterfly planetary nebula NGC 650-1 with the interstellar medium

    Science.gov (United States)

    Ramos-Larios, G.; Guerrero, M. A.; Nigoche-Netro, A.; Olguín, L.; Gómez-Muñoz, M. A.; Sabin, L.; Vázquez, R.; Akras, S.; Ramírez Vélez, J. C.; Chávez, M.

    2018-03-01

    With its bright and wide equatorial waist seen almost edge-on (`the butterfly body') and the faint and broad bipolar extensions (`the butterfly wings'), NGC 650-1 is the archetypical example of bipolar planetary nebula (PN) with butterfly morphology. We present here deep high-resolution broad- and narrow-band optical images that expose the rich and intricate fine structure of this bipolar PN, with small-scale bubble-like features and collimated outflows. A SHAPE spatio-kinematic model indicates that NGC 650-1 has a broad central torus with an inclination angle of 75° with respect to the line of sight, whereas that of the bipolar lobes, which are clearly seen in the position-velocity maps, is 85°. Large field of view deep images show, for first time, an arc-like diffuse envelope in low- and high-excitation emission lines located up to 180 arcsec towards the east-south-east of the central star, well outside the main nebula. This morphological component is confirmed by Spitzer MIPS and WISE infrared imaging, as well as by long-slit low- and high-dispersion optical spectroscopic observations. Hubble Space Telescope images of NGC 650-1 obtained at two different epochs ˜14 yr apart reveal the proper motion of the central star along this direction. We propose that this motion of the star through the interstellar medium compresses the remnant material of a slow asymptotic giant branch wind, producing this bow-shock-like feature.

  8. High-Speed Bullet Ejections during the AGB to Planetary Nebula Transition: A Study of the Carbon Star V Hydrae

    Science.gov (United States)

    Sahai, Raghvendra

    2017-08-01

    The carbon star V Hya is experiencing heavy mass loss as it undergoes the transition from an AGB star to a planetary nebula (PN). This is possibly the earliest object known in this brief phase, which is so short that few nearby stars are likely to be caught in the act. Molecular observations reveal that a bipolar nebula has been established even at this early stage. Using STIS, we obtained high spatial-resolution long-slit optical spectra of V Hya spanning 3 epochs spaced apart by a year during each of two periods (2002-2004, 2011-2013). These data reveal high-velocity emission in [SII] lines from compact blobs located both on- and off-source, with the ejection axis executing a flip-flop, both in, and perpendicular to, the sky-plane. We have proposed a detailed model in which V Hya ejects high-speed (200-250 km/s) bullets once every 8.5 yr associated with periastron passage of a binary companion in an eccentric orbit with an 8.5 yr period. We suggest that the jet driver is an accretion disk (produced by gravitational capture of material from the primary) that is warped and precessing. Our model predicts the locations of previously ejected bullets in V Hya and future epochs at which new bullets will emerge. We now propose new STIS observations of these remarkable bullet ejections over two new epochs well separated from previous ones, to robustly test our model. The proposed observations will provide us with an unprecedented opportunity to look on as V Hya's circumstellar envelope is sculpted by these bullets. Our study will help solve the long-standing puzzle of how the spherical mass-loss envelopes of AGB stars evolve into bipolar and multipolar PNe.

  9. Masses of the Planetary Nebula Central Stars in the Galactic Globular Cluster System from HST Imaging and Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jacoby, George H. [Lowell Observatory, Flagstaff, AZ 86001 (United States); Marco, Orsola De [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); Davies, James [Space Telescope Science Institute, Baltimore MD 21218 (United States); Lotarevich, I. [American Museum of Natural History, New York, NY (United States); Bond, Howard E. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Harrington, J. Patrick [University of Maryland, College Park, MD (United States); Lanz, Thierry, E-mail: gjacoby@lowell.edu, E-mail: orsola.demarco@mq.edu.au, E-mail: jdavies@stsci.edu, E-mail: heb11@psu.edu, E-mail: jph@astro.umd.edu, E-mail: thierry.lanz@oca.eu [Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, F-06304 Nice (France)

    2017-02-10

    The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the PN JaFu 1 with the Hubble Space Telescope (HST) to obtain photometry of its central star (CS) and high-resolution morphological information. We imaged IRAS 18333-2357 with better depth and resolution, and we analyzed its archival HST spectra to constrain its CS temperature and luminosity. All PNe in Galactic GCs now have quality HST data, allowing us to improve CS mass estimates. We find reasonably consistent masses between 0.53 and 0.58 M {sub ⊙} for all four objects, though estimates vary when adopting different stellar evolutionary calculations. The CS mass of IRAS 18333-2357, though, depends strongly on its temperature, which remains elusive due to reddening uncertainties. For all four objects, we consider their CS and nebula masses, their morphologies, and other incongruities to assess the likelihood that these objects formed from binary stars. Although generally limited by uncertainties (∼0.02 M {sub ⊙}) in post-AGB tracks and core mass versus luminosity relations, the high-mass CS in K 648 indicates a binary origin. The CS of JaFu 1 exhibits compact, bright [O iii] and H α emission, like EGB 6, suggesting a binary companion or disk. Evidence is weaker for a binary origin of JaFu 2.

  10. BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. IV. THE CENTRAL STARS OF HaTr 4 AND Hf 2-2

    Energy Technology Data Exchange (ETDEWEB)

    Hillwig, Todd C.; Schaub, S. C. [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States); Bond, Howard E. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Frew, David J. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Bodman, Eva H. L., E-mail: todd.hillwig@valpo.edu [Southeastern Association for Research in Astronomy (SARA) (United States)

    2016-08-01

    We explore the photometrically variable central stars of the planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments and data confirming the identification of both as close binaries with an irradiated cool companion to the hot central star. We include updated light curves, orbital periods, and preliminary binary modeling for both systems. We also identify for the first time the central star of HaTr 4 as an eclipsing binary. Neither system has been well studied in the past, but we utilize the small amount of existing data to limit possible binary parameters, including system inclination. These parameters are then compared to nebular parameters to further our knowledge of the relationship between binary central stars of planetary nebulae and nebular shaping and ejection.

  11. The gas turbulence in planetary nebulae: quantification and multi-D maps from long-slit, wide-spectral range echellograms

    Science.gov (United States)

    Sabbadin, F.; Turatto, M.; Benetti, S.; Ragazzoni, R.; Cappellaro, E.

    2008-09-01

    Context: This methodological paper is part of a short series dedicated to the long-standing astronomical problem of de-projecting the bi-dimensional, apparent morphology of a three-dimensional distribution of gas. Aims: We focus on the quantification and spatial recovery of turbulent motions in planetary nebulae (and other classes of expanding nebulae) by means of long-slit echellograms over a wide spectral range. Methods: We introduce some basic theoretical notions, discuss the observational methodology, and develop an accurate procedure disentangling all broadening components (instrumental resolution, thermal motions, turbulence, gradient of the expansion velocity, and fine structure of hydrogen-like ions) of the velocity profile in all spatial positions of each spectral image. This allows us to extract random, non-thermal motions at unprecedented accuracy, and to map them in 1-, 2- and 3-dimensions. Results: We discuss general and specific applications of the method. We present the solution to practical problems in the multi-dimensional turbulence-analysis of a testing-planetary nebula (NGC 7009), using the three-step procedure (spatio-kinematics, tomography, and 3D rendering) developed at the Astronomical Observatory of Padua (Italy). In addition, we introduce an observational paradigm valid for all spectroscopic parameters in all classes of expanding nebulae. Conclusions: Unsteady, chaotic motions at a local scale constitute a fundamental (although elusive) kinematical parameter of each planetary nebula, providing deep insights on its different shaping agents and mechanisms, and on their mutual interaction. The detailed study of turbulence, its stratification within a target and (possible) systematic variation among different sub-classes of planetary nebulae deserve long-slit, multi-position angle, wide-spectral range echellograms containing emissions at low-, medium-, and high-ionization, to be analyzed pixel-to-pixel with a straightforward and versatile

  12. Polycyclic aromatic hydrocarbons and molecular hydrogen in oxygen-rich planetary nebulae: the case of NGC 6720.

    Science.gov (United States)

    Cox, N L J; Pilleri, P; Berné, O; Cernicharo, J; Joblin, C

    2016-02-11

    Evolved stars are primary sources for the formation of polycyclic aromatic hydrocarbons (PAHs) and dust grains. Their circumstellar chemistry is usually designated as either oxygen-rich or carbon-rich, although dual-dust chemistry objects, whose infrared spectra reveal both silicate- and carbon-dust features, are also known. The exact origin and nature of this dual-dust chemistry is not yet understood. Spitzer -IRS mid-infrared spectroscopic imaging of the nearby, oxygen-rich planetary nebula NGC 6720 reveals the presence of the 11.3 μ m aromatic (PAH) emission band. It is attributed to emission from neutral PAHs, since no band is observed in the 7-8 μ m range. The spatial distribution of PAHs is found to closely follow that of the warm clumpy molecular hydrogen emission. Emission from both neutral PAHs and warm H 2 is likely to arise from photo-dissociation regions associated with dense knots that are located within the main ring. The presence of PAHs together with the previously derived high abundance of free carbon (relative to CO) suggest that the local conditions in an oxygen-rich environment can also become conducive to in-situ formation of large carbonaceous molecules, such as PAHs, via a bottom-up chemical pathway. In this scenario, the same stellar source can enrich the interstellar medium with both oxygen-rich dust and large carbonaceous molecules.

  13. Globular clusters and planetary nebulae kinematics and X-ray emission in the early-type galaxy NGC 5128

    Directory of Open Access Journals (Sweden)

    Samurović S.

    2006-01-01

    Full Text Available The estimates of the mass of the galaxy NGC 5128 based on the different mass tracers, globular clusters (GCs and planetary nebulae (PNe, are presented. These estimates are compared with the estimate based on the X-ray methodology and it is found that the results for the mass (and mass-to-light ratio for all three approaches are in very good agreement interior to 25 arcmin; beyond 25 arcmin the X-rays predict the mass which is too high with respect to the one found using GCs and PNe. Some possible explanations for this discrepancy were discussed. The Jeans equation is also solved and its predictions for the velocity dispersion are then compared with the observed values, which extend to ~8 effective radii in the case of the GCs and ~15 effective radii in the case of the PNe. It is found that interior to ~25 arcmin (~5 effective radii dark matter does not dominate because the total mass-to-light ratio in the B band in solar units is less than 10. Based on the GCs and PNe beyond ~25 arcmin the total mass-to-light ratio increases to ~14 (at ~80 arcmin which indicates the existence of dark matter in the outer regions of NGC 5128.

  14. Analysis of Co-spatial UV-optical HST/STIS Spectra of Planetary Nebula NGC 3242

    Science.gov (United States)

    Miller, Timothy R.; Henry, Richard B. C.; Balick, Bruce; Kwitter, Karen B.; Dufour, Reginald J.; Shaw, Richard A.; Corradi, Romano L. M.

    2016-10-01

    This project sought to consider two important aspects of the planetary nebula NGC 3242 using new long-slit HST/STIS spectra. First, we investigated whether this object is chemically homogeneous by spatially dividing the slit into different regions and calculating the abundances of each region. The major result is that the elements of He, C, O, and Ne are chemically homogeneous within uncertainties across the regions probed, implying that the stellar outflow was well-mixed. Second, we constrained the stellar properties using photoionization models computed by CLOUDY and tested the effects of three different density profiles on these parameters. The three profiles tested were a constant density profile, a Gaussian density profile, and a Gaussian with a power-law density profile. The temperature and luminosity were not affected significantly by the choice of density structure. The values for the stellar temperature and luminosity from our best-fit model are {89.7}-4.7+7.3 kK and log(L/L ⊙) = {3.36}-0.22+0.28, respectively. Comparing to evolutionary models on an HR diagram, this corresponds to an initial and final mass of {0.95}-0.09+0.35{M}⊙ and {0.56}-0.01+0.01{M}⊙ , respectively. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

  15. The Fornax Cluster VLT Spectroscopic Survey II - Planetary Nebulae kinematics within 200 kpc of the cluster core

    Science.gov (United States)

    Spiniello, C.; Napolitano, N. R.; Arnaboldi, M.; Tortora, C.; Coccato, L.; Capaccioli, M.; Gerhard, O.; Iodice, E.; Spavone, M.; Cantiello, M.; Peletier, R.; Paolillo, M.; Schipani, P.

    2018-03-01

    We present the largest and most spatially extended planetary nebulae (PNe) catalog ever obtained for the Fornax cluster. We measured velocities of 1452 PNe out to 200 kpc in the cluster core using a counter-dispersed slitless spectroscopic technique with data from FORS2 on the VLT. With such extended spatial coverage, we can study separately the stellar halos of some of the cluster main galaxies and the intracluster light. In this second paper of the Fornax Cluster VLT Spectroscopic Survey (FVSS), we identify and classify the emission-line sources, describe the method to select PNe and calculate their coordinates and velocities from the dispersed slitless images. From the PN 2D velocity map we identify stellar streams that are possibly tracing the gravitational interaction of NGC 1399 with NGC 1404 and NGC 1387. We also present the velocity dispersion profile out to ˜200 kpc radii, which shows signatures of a superposition of the bright central galaxy and the cluster potential, with the latter clearly dominating the regions outside R˜1000″(˜100 kpc).

  16. A new look inside planetary nebula LoTr 5: a long-period binary with hints of a possible third component

    Science.gov (United States)

    Aller, A.; Lillo-Box, J.; Vučković, M.; Van Winckel, H.; Jones, D.; Montesinos, B.; Zorotovic, M.; Miranda, L. F.

    2018-05-01

    LoTr 5 is a planetary nebula with an unusual long-period binary central star. As far as we know, the pair consists of a rapidly rotating G-type star and a hot star, which is responsible for the ionization of the nebula. The rotation period of the G-type star is 5.95 d and the orbital period of the binary is now known to be ˜2700 d, one of the longest in central star of planetary nebulae. The spectrum of the G central star shows a complex H α double-peaked profile which varies with very short time-scales, also reported in other central stars of planetary nebulae and whose origin is still unknown. We present new radial velocity observations of the central star which allow us to confirm the orbital period for the long-period binary and discuss the possibility of a third component in the system at ˜129 d to the G star. This is complemented with the analysis of archival light curves from Super Wide Angle Search for Planets, All Sky Automated Survey, and Optical Monitoring Camera. From the spectral fitting of the G-type star, we obtain an effective temperature of Teff = 5410 ± 250 K and surface gravity of log g = 2.7 ± 0.5, consistent with both giant and subgiant stars. We also present a detailed analysis of the H α double-peaked profile and conclude that it does not present correlation with the rotation period and that the presence of an accretion disc via Roche lobe overflow is unlikely.

  17. The fast, massive outflow of the pre-planetary nebula IRAS 19374+2356

    Science.gov (United States)

    Sánchez Contreras, C.; Martin, S.; Sahai, R.

    2013-05-01

    At some point in the late-AGB stage, a process (or processes) becomes operative that accelerates and imposes bipolarity upon the slow, spherical AGB winds. What produces bipolarity in these objects and at what stage does bipolarity manifest itself are key questions that remain yet poorly understood. We present CO (115 & 230 GHz) emission maps of IRAS19374+2359, an extreme pre-PN with an unparalleledly massive, fast molecular outflow discovered in our OVRO Post-AGB CO 1-0 emission Survey (referred to as OPACOS; Sánchez Contreras & Sahai 2012, ApJS, 203, 16). We present sub-arcsecond resolution ^{(12,13)}CO 2-1 and 1.3 mm-continuum interferometric maps recently obtained with the Submillimeter Array (SMA) together with our discovery ˜8s-resolution ^{(12,13)}CO 1-0 OVRO data. The prominent ˜300 km s^{-1}-broad wings and the lack of an intense, low-velocity CO line core in IRAS 19374 indicate that most or all of the molecular gas participates in the high-velocity flow. From our CO data, we estimate a total mass in the molecular outflow of ˜ 1 msun and an unprecedentedly large value for the linear momemtum carried of ≥ 45 msun km s^{-1}. Our SMA maps show CO emission arising from a ˜3s×2s hourglass-shaped molecular flow aligned with the optical lobes; a linear velocity gradient along the lobes as well as equatorial expansion at the nebula waist are found. The spatio-kinematic structure of this object is in support of a jet-envelope entrainment scenario in which a substantial amount of directed momentum is transferred to large parts of the dense AGB wind by interaction with fast, collimated post-AGB jets.

  18. Chemical abundances in the extremely carbon-rich and xenon-rich halo planetary nebula H4-1

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Masaaki [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Tajitsu, Akito, E-mail: otsuka@asiaa.sinica.edu.tw, E-mail: tajitsu@subaru.naoj.org [Subaru Telescope, NAOJ, 650 North A' ohoku Place, Hilo, HI 96720 (United States)

    2013-12-01

    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ∼ –2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] λ5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M {sub ☉} single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  19. OT1_tueta_2: Far-IR Emission from Planetary Nebulae: Simultaneous Mapping and Spectral Probing of the Multi-Phased Dusty Gaseous System

    Science.gov (United States)

    Ueta, T.

    2010-07-01

    We propose to undertake an ambitious Herschel large survey of planetary nebulae (PNs), mustering the full strengths of Herschel's broadband mapping, spectral mapping, and spatio-spectroscopic capabilities. Our proposed PN survey will exploit Herschel's unprecedented spatial-resolving power in the far-IR wavelengths to its fullest potential. We will perform (1) deep PACS/SPIRE broadband mapping to account for the coldest dust component of the nebulae in the target PNs and determine the spatial distribution of the dusty PN haloes, (2) exhaustive PACS/SPIRE line mapping in far-IR fine-structure and CO transition lines in two representative PNs to diagnose the energetics of the nebulae as a function of location in the nebulae, and (3) PACS/SPIRE spectral-energy-distribution spectroscopy at several positions in the target PNs to understand variations in the physical conditions as a function of location in the nebulae. This PN survey is distinguished from the existing MESS KPGT program by the extra dimension added by spectral mapping and spatio-spectroscopy that permit simultaneous probing of the gas and dust component in the target PNs. Through these investigations, we will consider the energetics of the entire gas-dust system as a function of location in the nebulae. Herschel will allow us to take this novel approach which has rarely been taken previously. The proposed Herschel survey will be conducted in collaboration with the recently-approved Chandra X-ray Observatory Large Project to furnish substantial PN data resources that would allow us - a community of PN astronomers - to tackle a multitude of unanswered issues in PN physics, from the shaping mechanisms of the nebulae to the energetics of the multi-phased gas-dust system surrounding the central white dwarf. The proposed Herschel survey and the approved Chandra survey, combined with the community assets from optical to mid-IR, will provide an extremely valuable and comprehensive compilation of PN resource that

  20. The filamentary nebulae S 188

    International Nuclear Information System (INIS)

    Rosado, M.; Kwitter, K.B.

    1982-01-01

    The crescent shaped nebula S 188 is identified as a planetary nebula (PN) of Peimbert's Type I on the basis of its observed nebula spectrum. New FP interferometric work allows to determine the systemic motion of this nebula. The derived kinematical distance exceeds Cudworth's distance estimate supporting the idea that Peimbert's Type I PNs have larger ejected masses than typical PNs. A discussion about the origin of its non-spherical shape is also given. (author)

  1. The First Extensive Molecular Study of AN Oxygen-Rich Planetary Nebula: Observations of SiO, SO_2, and so

    Science.gov (United States)

    Edwards, Jessica L.; Ziurys, Lucy M.

    2013-06-01

    A majority of stars will go through the Planetary Nebula (PN) phase during their stellar lifetimes, becoming significant contributors to the chemical enrichment of the interstellar medium. Planetary Nebulae (PNe) in general are poorly understood, both physically and chemically. The PN M2-48 is an interesting candidate for study because not only is it clearly oxygen-rich, but also because it has an age of ˜5,000 years; i.e. is about mid-way through the PN stage. Previous studies of PNe have been in either very young (˜700-1,500 years) or very old (˜12,000 years) objects. Observations of M2-48 have been carried out with the Sub-Millimeter Telescope and the 12-meter Antenna of the Arizona Radio Observatory. CO, CN, HCN, HNC, HCO^{+}, CS, SO, SO_2, and SiO have been detected. CS and SO were recently detected in the barely oxygen-rich NGC 6537, but this is the first detection of SO_2 and SiO in a PN. Indeed, age does not appear to dictate PN chemistry, but rather the chemical makeup of the progenitor AGB star. Analysis is currently under way to model the molecular abundances in this object. Most current results will be presented.

  2. A SOFIA FORCAST Grism Study of the Mineralogy of Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables

    International Nuclear Information System (INIS)

    Arneson, R. A.; Gehrz, R. D.; Woodward, C. E.; Shenoy, D.; Helton, L. A.; Evans, A.; Keller, L. D.; Hinkle, K. H.; Jura, M.; Lebzelter, T.; Lisse, C. M.; Rushton, M. T.; Mizrachi, J.

    2017-01-01

    We present a SOFIA FORCAST grism spectroscopic survey to examine the mineralogy of the circumstellar dust in a sample of post-asymptotic giant branch (post-AGB) yellow supergiants that are believed to be the precursors of planetary nebulae. Our mineralogical model of each star indicates the presence of both carbon-rich and oxygen-rich dust species—contrary to simple dredge-up models—with a majority of the dust in the form of amorphous carbon and graphite. The oxygen-rich dust is primarily in the form of amorphous silicates. The spectra do not exhibit any prominent crystalline silicate emission features. For most of the systems, our analysis suggests that the grains are relatively large and have undergone significant processing, supporting the hypothesis that the dust is confined to a Keplerian disk and that we are viewing the heavily processed, central regions of the disk from a nearly face-on orientation. These results help to determine the physical properties of the post-AGB circumstellar environment and to constrain models of post-AGB mass loss and planetary nebula formation.

  3. A SOFIA FORCAST Grism Study of the Mineralogy of Dust in the Winds of Proto-planetary Nebulae: RV Tauri Stars and SRd Variables

    Energy Technology Data Exchange (ETDEWEB)

    Arneson, R. A.; Gehrz, R. D.; Woodward, C. E.; Shenoy, D. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 106 Pleasant Street S.E., Minneapolis, MN 55455 (United States); Helton, L. A. [USRA-SOFIA Science Center, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Evans, A. [Astrophysics Group, Lennard Jones Laboratory, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Keller, L. D. [Department of Physics and Astronomy, 264 Center for Natural Sciences, Ithaca College, Ithaca, NY 14850 (United States); Hinkle, K. H. [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States); Jura, M. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Lebzelter, T. [Institute for Astrophysics (IfA), University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Lisse, C. M. [Solar System Exploration Branch, Space Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Rushton, M. T. [Astronomical Institute of the Romanian Academy, Str. Cutitul de Argint 5, Bucharest, 040557 (Romania); Mizrachi, J., E-mail: arneson@astro.umn.edu [Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States)

    2017-07-01

    We present a SOFIA FORCAST grism spectroscopic survey to examine the mineralogy of the circumstellar dust in a sample of post-asymptotic giant branch (post-AGB) yellow supergiants that are believed to be the precursors of planetary nebulae. Our mineralogical model of each star indicates the presence of both carbon-rich and oxygen-rich dust species—contrary to simple dredge-up models—with a majority of the dust in the form of amorphous carbon and graphite. The oxygen-rich dust is primarily in the form of amorphous silicates. The spectra do not exhibit any prominent crystalline silicate emission features. For most of the systems, our analysis suggests that the grains are relatively large and have undergone significant processing, supporting the hypothesis that the dust is confined to a Keplerian disk and that we are viewing the heavily processed, central regions of the disk from a nearly face-on orientation. These results help to determine the physical properties of the post-AGB circumstellar environment and to constrain models of post-AGB mass loss and planetary nebula formation.

  4. A Search for Mid-Infrared Emission Lines of F and Na in Planetary Nebulae with EXES on SOFIA: Testing AGB Nucleosynthesis

    Science.gov (United States)

    Dinerstein, Harriet L.; Sterling, N. C.; Richter, Matthew J.; DeWitt, Curtis; Montiel, Edward J.; Karakas, Amanda I.

    2018-01-01

    We report results from a search for mid-infrared emission lines of F (Z = 9) and Na (Z =11) in planetary nebulae using the Echelon-Cross-Echelle Spectrometer, EXES (DeWitt, C., et al. 2012, SPIE, 8446, id. 84461A) on the Stratospheric Facility for Infrared Astronomy (SOFIA Young et al. 2012, ApJL, 749, L17). As the envelopes of former AGB stars, planetary nebulae carry the imprint of all nuclear reactions that occurred over the star’s lifetime. Complex sequences of reactions during the late evolutionary stages may produce – or in some cases destroy – F and Na. Due to sensitivity to uncertainties in the interior physical conditions and key processes (e.g. convection, mass loss), their predicted final abundances vary widely for different sets of theoretical models (Karakas & Lugaro 2016, ApJ, 825, 26). During a flight series with EXES in May 2017, we looked for [Na III] 7.39 μm and the as-yet undetected fine structure transitions [F IV] 25.8 μm and [F V] 13.4 μm. The F lines were observed at resolving power R = 50,000, while Na was observed with R ≈ 2000. We observed a spectral region containing the [F IV] line and [O IV] 25.9 μm in 3 planetary nebulae descended from stars of ≈ 2.5 – 4 M⊙ (NGC 6886, NGC 7027, and Hb 5), and [F V] in NGC 7027 only. We observed NGC 6886 and IC 5117 in the [Na III] setting, which included the H I 6-5 Pfund α line at 7.46 μm. Simultaneous measurement of O+3 and H+ enables us to derive reliable ionic abundance ratios from the [F IV] and [Na III] lines. We obtained high S/N on the [Na III] line in IC 5117 but were unsuccessful in detecting either F line in any of our targets. We present our upper limits, compare them to values in the literature from optical spectra, and discuss our findings in the context of evolutionary models.This research is supported by NASA/USRA subcontract SOF 05-0121. Support for EXES is provided via collaborative agreement NNXAI85A between NASA Ames Research Center and the University of

  5. Models of the Mass-ejection Histories of Pre-planetary Nebulae. II. The Formation of Minkowski’s Butterfly and its Proboscis in M2–9

    Science.gov (United States)

    Balick, Bruce; Frank, Adam; Liu, Baowei; Corradi, Romano

    2018-02-01

    M2–9, or the “Minkowski’s Butterfly,” is one of the most iconic outflow sources from an evolved star. In this paper we present a hydrodynamic model of M2–9 in which the nebula is formed and shaped by a steady, low-density (“light”), mildly collimated “spray” of gas injected at 200 km s‑1 that interacts with a far denser, intrinsically simple pre-existing AGB wind that has slowly formed all of the complex features within M2–9’s lobes (including the knot pairs N3/S3 and N4/S4 at their respective leading edges, and the radial gradient of Doppler shifts within 20″ of the nucleus). We emphasize that the knot pairs are not ejected from the star but formed in situ. In addition, the observed radial speed of the knots is only indirectly related to the speed of the gas injected by the star. The model allows us to probe the early history of the wind geometry and lobe formation. We also formulate a new estimate of the nebular distance D = 1.3 kpc. The physical mechanism that accounts for the linear radial speed gradient in M2–9 applies generally to many other pre-planetary nebulae whose hollow lobes exhibit similar gradients along their edges.

  6. A New Radio Spectral Line Survey of Planetary Nebulae: Exploring Radiatively-driven Heating and Chemistry of Molecular Gas

    Science.gov (United States)

    Bublitz, Jesse; Kastner, Joel H.; Santander-García, Miguel; Montez, Rodolfo; Alcolea, Javier; Balick, Bruce; Bujarrabal, Valentín

    2018-01-01

    We report the results of a survey of mm-wave molecular line emission from nine nearby (molecular line frequencies were chosen to investigate the molecular chemistry of these nebulae. New detections of one or more of five molecules -- the molecular mass tracer 13CO and the chemically important trace species HCO+, CN, HCN, and HNC -- were made in at least one PN. We present analysis of emission line flux ratios that are potential diagnostics of the influence that ultraviolet and X-ray radiation have on the chemistry of residual molecular gas in PNe.

  7. Ant nebula

    Science.gov (United States)

    1999-01-01

    A new Hubble Space Telescope image of a celestial object called the Ant Nebula may shed new light on the future demise of our Sun. The image is available at http://www.jpl.nasa.gov/pictures/wfpc . The nebula, imaged on July 20, 1997, and June 30, 1998, by Hubble's Wide Field and Planetary Camera 2, was observed by Drs. Raghvendra Sahai and John Trauger of NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Bruce Balick of the University of Washington in Seattle; and Vincent Icke of Leiden University in the Netherlands. JPL designed and built the camera. The Ant Nebula, whose technical name is Mz3, resembles the head and thorax of an ant when observed with ground-based telescopes. The new Hubble image, with 10 times the resolution revealing 100 times more detail, shows the 'ant's' body as a pair of fiery lobes protruding from a dying, Sun- like star. The Ant Nebula is located between 3,000 and 6,000 light years from Earth in the southern constellation Norma. The image challenges old ideas about what happens to dying stars. This observation, along with other pictures of various remnants of dying stars called planetary nebulae, shows that our Sun's fate will probably be much more interesting, complex and dramatic than astronomers previously believed. Although the ejection of gas from the dying star in the Ant Nebula is violent, it does not show the chaos one might expect from an ordinary explosion, but instead shows symmetrical patterns. One possibility is that the central star has a closely orbiting companion whose gravitational tidal forces shape the outflowing gas. A second possibility is that as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Electrically charged winds, much like those in our Sun's solar wind but millions of times denser and moving at speeds up to 1,000 kilometers per second (more than 600 miles per second) from the star, follow the twisted field lines on their way out into space

  8. GTC/CanariCam Mid-IR Imaging of the Fullerene-rich Planetary Nebula IC 418: Searching for the Spatial Distribution of Fullerene-like Molecules

    Science.gov (United States)

    Díaz-Luis, J. J.; García-Hernández, D. A.; Manchado, A.; García-Lario, P.; Villaver, E.; García-Segura, G.

    2018-03-01

    We present seeing-limited narrow-band mid-IR GTC/CanariCam images of the spatially extended fullerene-containing planetary nebula (PN) IC 418. The narrow-band images cover the C60 fullerene band at 17.4 μm, the polycyclic aromatic hydrocarbon like (PAH-like) feature at 11.3 μm, the broad 9–13 μm feature, and their adjacent continua at 9.8 and 20.5 μm. We study the relative spatial distribution of these complex species, all detected in the Spitzer and Infrared Space Observatory spectra of IC 418, with the aim of getting observational constraints to the formation process of fullerenes in H-rich circumstellar environments. A similar ring-like extended structure is seen in all narrow-band filters, except in the dust continuum emission at 9.8 μm, which peaks closer to the central star. The continuum-subtracted images display a clear ring-like extended structure for the carrier of the broad 9–13 μm emission, while the spatial distribution of the (PAH-like) 11.3 μm emission is not so well defined. Interestingly, a residual C60 17.4 μm emission (at about 4σ from the sky background) is seen when subtracting the dust continuum emission at 20.5 μm. This residual C60 emission, if real, might have several interpretations, the most exciting being perhaps that other fullerene-based species like hydrogenated fullerenes with very low H-content may contribute to the observed 17.4 μm emission. We conclude that higher sensitivity mid-IR images and spatially resolved spectroscopic observations (especially in the Q-band) are necessary to get some clues about fullerene formation in PNe.

  9. Limits on [O III] 5007 Emission from NGC 4472's Globular Clusters: Constraints on Planetary Nebulae and Ultraluminous Black Hole X-Ray Binaries in Globular Clusters

    Science.gov (United States)

    Peacock, Mark B.; Zepf, Stephen E.; Maccarone, Thomas J.

    2012-06-01

    We have searched for [O III] 5007 emission in high-resolution spectroscopic data from FLAMES/GIRAFFE Very Large Telescope observations of 174 massive globular clusters (GCs) in NGC 4472. No planetary nebulae (PNe) are observed in these clusters, constraining the number of PNe per bolometric luminosity, α evolution, if all stars produce PNe. Comparing our results to populations of PNe in galaxies, we find most galaxies have a higher α than these GCs (more PNe per bolometric luminosity—though some massive early-type galaxies do have similarly low α). The low α required in these GCs suggests that the number of PNe per bolometric luminosity does not increase strongly with decreasing mass or metallicity of the stellar population. We find no evidence for correlations between the presence of known GC PNe and either the presence of low-mass X-ray binaries (LMXBs) or the stellar interaction rates in the GCs. This, and the low α observed, suggests that the formation of PNe may not be enhanced in tight binary systems. These data do identify one [O III] emission feature, this is the (previously published) broad [O III] emission from the cluster RZ 2109. This emission is thought to originate from the LMXB in this cluster, which is accreting at super-Eddington rates. The absence of any similar [O III] emission from the other clusters favors the hypothesis that this source is a black hole LMXB, rather than a neutron star LMXB with significant geometric beaming of its X-ray emission.

  10. On the production of He, C, and N by low- and intermediate-mass stars: a comparison of observed and model-predicted planetary nebula abundances

    Science.gov (United States)

    Henry, R. B. C.; Stephenson, B. G.; Miller Bertolami, M. M.; Kwitter, K. B.; Balick, B.

    2018-01-01

    The primary goal of this paper is to make a direct comparison between the measured and model-predicted abundances of He, C, and N in a sample of 35 well-observed Galactic planetary nebulae (PNe). All observations, data reductions, and abundance determinations were performed in house to ensure maximum homogeneity. Progenitor star masses (M ≤ 4 M⊙) were inferred using two published sets of post-asymptotic giant branch model tracks and L and Teff values. We conclude the following: (1) the mean values of N/O across the progenitor mass range exceeds the solar value, indicating significant N enrichment in the majority of our objects; (2) the onset of hot bottom burning appears to begin around 2 M⊙, i.e. lower than ∼5 M⊙ implied by theory; (3) most of our objects show a clear He enrichment, as expected from dredge-up episodes; (4) the average sample C/O value is 1.23, consistent with the effects of third dredge up; and (5) model grids used to compare to observations successfully span the distribution over metallicity space of all C/O and many He/H data points but mostly fail to do so in the case of N/O. The evident enrichment of N in PN and the general discrepancy between the observed and model-predicted N/O abundance ratios signal the need for extra mixing as an effect of rotation and/or thermohaline mixing in the models. The unexpectedly high N enrichment that is implied here for low-mass stars, if confirmed, will likely impact our conclusions about the source of N in the Universe.

  11. Chemical Abundances of Planetary Nebulae in the Substructures of M31. II. The Extended Sample and a Comparison Study with the Outer-disk Group

    Science.gov (United States)

    Fang, Xuan; García-Benito, Rubén; Guerrero, Martín A.; Zhang, Yong; Liu, Xiaowei; Morisset, Christophe; Karakas, Amanda I.; Miller Bertolami, Marcelo M.; Yuan, Haibo; Cabrera-Lavers, Antonio

    2018-01-01

    We report deep spectroscopy of 10 planetary nebulae (PNe) in the Andromeda Galaxy (M31) using the 10.4 m Gran Telescopio Canarias (GTC). Our targets reside in different regions of M31, including halo streams and the dwarf satellite M32, and kinematically deviate from the extended disk. The temperature-sensitive [O III] λ4363 line is observed in all PNe. For four PNe, the GTC spectra extend beyond 1 μm, enabling the explicit detection of the [S III] λ6312 and λλ9069, 9531 lines and thus determination of the [S III] temperature. Abundance ratios are derived and generally consistent with AGB model predictions. Our PNe probably all evolved from low-mass (stream. We thus speculate that our halo PNe formed in the Giant Stream’s progenitor through extended star formation. Alternatively, they might have formed from the same metal-rich gas as did the outer-disk PNe but were displaced into their present locations as a result of galactic interactions. These interpretations are, although speculative, qualitatively in line with the current picture, as inferred from previous wide-field photometric surveys, that M31's halo is the result of complex interactions and merger processes. The behavior of the N/O of the combined sample of the outer-disk and our halo/substructure PNe signifies that hot bottom burning might actually occur at <3 M ⊙ but careful assessment is needed. Based on observations made with the Gran Telescopio Canarias, installed at the Spanish Observatorio del Roque de los Muchachos of Instituto de Astrofísica de Canarias, in the island of La Palma. The observations presented in this paper are associated with GTC programs #GTC66-16A and #GTC25-16B.

  12. Neutron-capture element abundances in the planetary nebula NGC 5315 from deep optical and near-infrared spectrophotometry★†

    Science.gov (United States)

    Madonna, S.; García-Rojas, J.; Sterling, N. C.; Delgado-Inglada, G.; Mesa-Delgado, A.; Luridiana, V.; Roederer, I. U.; Mashburn, A. L.

    2017-10-01

    We analyse the chemical composition of the planetary nebula (PN) NGC 5315, through high-resolution (R ˜ 40000) optical spectroscopy with Ultraviolet-Visual Echelle Spectrograph at the Very Large Telescope, and medium-resolution (R ˜ 4800) near-infrared spectroscopy with Folded-port InfraRed Echellette at Magellan Baade Telescope, covering a wide spectral range from 0.31 to 2.50 μm. The main aim of this work is to investigate neutron (n)-capture element abundances to study the operation of the slow n-capture ('s-process') in the asymptotic giant branch (AGB) progenitor of NGC 5315. We detect more than 700 emission lines, including ions of the n-capture elements Se, Kr, Xe and possibly Br. We compute physical conditions from a large number of diagnostic line ratios, and derive ionic abundances for species with available atomic data. The total abundances are computed using recent ionization correction factors (ICFs) or by summing ionic abundances. Total abundances of common elements are in good agreement with previous work on this object. Based on our abundance analysis of NGC 5315, including the lack of s-process enrichment, we speculate that the most probable evolutionary scenario is that the progenitor star is in a binary system as hinted at by radial velocity studies, and interactions with its companion truncated the AGB before s-process enrichment could occur. However there are other two possible scenarios for its evolution, that cannot be ruled out: (I) the progenitor is a low-mass single star that did not undergo third dredge-up; (II) the progenitor star of NGC 5315 had an initial mass of 3-5 M⊙, and any s-process enhancements were heavily diluted by the massive envelope during the AGB phase.

  13. CO Isotopes in Planetary Nebulae

    OpenAIRE

    Balser, Dana S.; McMullin, Joseph P.; Wilson, T. L.

    2002-01-01

    Standard stellar evolution theory is inconsistent with the observed isotopic carbon ratio, 12C/13C, in evolved stars. This theory is also inconsistent with the 3He/H abundance ratios observed in Galactic HII regions, when combined with chemical evolution theory. These discrepancies have been attributed to an extra, non-standard mixing which further processes material during the RGB and should lower both the 12C/13C and 3He/H abundance ratios for stars with masses < 2 solar masses. Measurement...

  14. Angular diameters of Magellanic Cloud plantary nebulae. I. Speckle interferometry

    International Nuclear Information System (INIS)

    Wood, P.R.; Bessell, M.S.; Dopita, M.A.

    1986-01-01

    Speckle interferometric angular diameters of Magellanic Cloud planetary nebulae are presented. The mass of ionized gas in each nebula has been derived from the angular diameter and published H-beta line fluxes; the derives masses range from less than 0.006 to more than 0.19 solar mass. The planetary nebulae observed were the brightest in the Magellanic Clouds; consequently, they are all relatively small, young, bright, and dense. They are almost certainly only partially ionized, so that the masses derived for the ionized parts of the nebula are lower limits to the total nebula mass. The properties of the Magellanic Cloud nebulae are compared with those of planetary nebulae at the galactic center. 27 references

  15. Planetary compositions

    International Nuclear Information System (INIS)

    Taylor, S.R.

    1988-01-01

    The present study of the density, major-element and trace-element compositions, oxygen isotopes, and noble gases of the metal, sulfide, and silicate components of meteorites shows that these properties do not match those of the terrestrial planets, and thereby suggests that there was not much lateral mixing in the solar nebula during planetary accretion. The planets would then have accumulated from narrow concentric zones, and the current zonal structure of the asteroid belt may be analogous to the structure of the inner portions of the solar nebula during the terrestrial planets' accretion. Localized heating during the material's infall to the median plane of the nebula is suggested to have occurred. 64 references

  16. Modelling pulsar wind nebulae

    CERN Document Server

    2017-01-01

    In view of the current and forthcoming observational data on pulsar wind nebulae, this book offers an assessment of the theoretical state of the art of modelling them. The expert authors also review the observational status of the field and provide an outlook for future developments. During the last few years, significant progress on the study of pulsar wind nebulae (PWNe) has been attained both from a theoretical and an observational perspective, perhaps focusing on the closest, more energetic, and best studied nebula: the Crab, which appears in the cover. Now, the number of TeV detected PWNe is similar to the number of characterized nebulae observed at other frequencies over decades of observations. And in just a few years, the Cherenkov Telescope Array will increase this number to several hundreds, actually providing an essentially complete account of TeV emitting PWNe in the Galaxy. At the other end of the multi-frequency spectrum, the SKA and its pathfinder instruments, will reveal thousands of new pulsa...

  17. Observing nebulae

    CERN Document Server

    Griffiths, Martin

    2016-01-01

    This book enables anyone with suitable instruments to undertake an examination of nebulae and see or photograph them in detail. Nebulae, ethereal clouds of gas and dust, are among the most beautiful objects to view in the night sky. These star-forming regions are a common target for observers and photographers. Griffiths describes many of the brightest and best nebulae and includes some challenges for the more experienced observer. Readers learn the many interesting astrophysical properties of these clouds, which are an important subject of study in astronomy and astrobiology. Non-mathematical in approach, the text is easily accessible to anyone with an interest in the subject. A special feature is the inclusion of an observational guide to 70 objects personally observed or imaged by the author. The guide also includes photographs of each object for ease of identification along with their celestial coordinates, magnitudes and other pertinent information. Observing Nebulae provides a ready resource to allow an...

  18. Starlight excitation of permitted lines in gaseous nebulae

    International Nuclear Information System (INIS)

    Grandi, S.A.

    1975-01-01

    The weak heavy element permitted lines observed in the spectra of gaseous nebula have, with only a few exceptions, been thought to be excited only by recombination. The accuracy of this assumption for individual lines in nebula spectra is investigated in detail via model nebula calculations. First, approximations and techniques of calculation are considered for the three possible excitation mechanisms: recombination, resonance fluorescence by the starlight continuum, and resonance fluorescence by other nebular emission lines. Next, the permitted lines of O I as observed in gaseous nebulae are discussed. Thirdly, it is shown that varying combinations of recombination, resonance fluorescence by starlight, and resonance fluorescence by other nebula lines can successfully account for the observed strengths in the Orion Nebula of lines of the following ions: C II, N I, N II, N III, O II, Ne II, Si II, Si III, and S III. A similar analysis is performed for the lines in the spectra of the planetary nebulae NGC7662 and NGC7027, and, with some exceptions, satisfactory agreement between the observed and predicted line strengths is found. Finally, observations of the far red spectra of the Orion Nebula, the planetary nebulae NGC3242, NGC6210, NGC2392, IC3568, IC4997, NGC7027, and MGC7662, and the reflection nebulae IC431 and NGC2068 are reported

  19. Gamma-rays and neutrinos from the pulsar wind nebulae

    International Nuclear Information System (INIS)

    Bednarek, W.; Bartosik, M.

    2005-01-01

    We construct the time-dependent radiation model for the pulsar wind nebulae (PWNe), assuming that leptons are accelerated in resonant scattering with heavy nuclei, which are injected into the nebula by the pulsar. The equilibrium spectra of these particles inside the nebula are calculated taking into account their radiation and adiabatic energy losses. The spectra of γ-rays produced by these particles are compared with the observations of the PWNe emitting TeV γ-rays and predictions are made for the expected γ-ray fluxes from other PWNe. Expected neutrino fluxes and neutrino event rates in a 1 km 2 neutrino detector from these nebulae are also calculated. It is concluded that only the Crab Nebula can produce a detectable neutrino event rate in the 1 km 2 neutrino detector. Other PWNe can emit TeV γ-rays on the level of a few percent of that observed from the Crab Nebula

  20. LIMITS ON [O III] 5007 EMISSION FROM NGC 4472'S GLOBULAR CLUSTERS: CONSTRAINTS ON PLANETARY NEBULAE AND ULTRALUMINOUS BLACK HOLE X-RAY BINARIES IN GLOBULAR CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Peacock, Mark B.; Zepf, Stephen E. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Maccarone, Thomas J., E-mail: mpeacock@msu.edu [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2012-06-20

    We have searched for [O III] 5007 emission in high-resolution spectroscopic data from FLAMES/GIRAFFE Very Large Telescope observations of 174 massive globular clusters (GCs) in NGC 4472. No planetary nebulae (PNe) are observed in these clusters, constraining the number of PNe per bolometric luminosity, {alpha} < 0.8 Multiplication-Sign 10{sup -7} PN/L{sub Sun }. This is significantly lower than the rate predicted from stellar evolution, if all stars produce PNe. Comparing our results to populations of PNe in galaxies, we find most galaxies have a higher {alpha} than these GCs (more PNe per bolometric luminosity-though some massive early-type galaxies do have similarly low {alpha}). The low {alpha} required in these GCs suggests that the number of PNe per bolometric luminosity does not increase strongly with decreasing mass or metallicity of the stellar population. We find no evidence for correlations between the presence of known GC PNe and either the presence of low-mass X-ray binaries (LMXBs) or the stellar interaction rates in the GCs. This, and the low {alpha} observed, suggests that the formation of PNe may not be enhanced in tight binary systems. These data do identify one [O III] emission feature, this is the (previously published) broad [O III] emission from the cluster RZ 2109. This emission is thought to originate from the LMXB in this cluster, which is accreting at super-Eddington rates. The absence of any similar [O III] emission from the other clusters favors the hypothesis that this source is a black hole LMXB, rather than a neutron star LMXB with significant geometric beaming of its X-ray emission.

  1. Comparative Absorption and Emission Abundance Analyses of Nebulae: Ion Emission Densities for IC 418

    Science.gov (United States)

    Williams, Robert; Jenkins, Edward B.; Baldwin, Jack A.; Sharpee, Brian

    2003-02-01

    Recent analyses of nebular spectra have resulted in discrepant abundances from CNO forbidden and recombination lines. We consider independent methods of determining ion abundances for emission nebulae, comparing ion emission measures with column densities derived from resonance absorption lines viewed against the central star continuum. Separate analyses of the nebular emission lines and the stellar UV absorption lines yield independent abundances for ions, and their ratio can be expressed in terms of a parameter em, the ``emission density'' for each ion. Adequate data for this technique are still scarce, but separate analyses of spectra of the planetary nebula and central star of IC 418 do show discrepant abundances for several ions, especially Fe II. The discrepancies are probably due to the presence of absorbing gas that does not emit and/or to uncertain atomic data and excitation processes, and they demonstrate the importance of applying the technique of combining emission- and absorption-line data in deriving abundances for nebulae. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555, and on observations made at CTIO/NOAO, which is operated by AURA, Inc., under cooperative agreement with the NSF.

  2. N44C nebula

    Science.gov (United States)

    1999-01-01

    Resembling the hair in Botticelli's famous portrait of the birth of Venus, an image from NASA's Hubble Space Telescope has captured softly glowing filaments streaming from hot young stars in a nearby nebula. The image, presented by the Hubble Heritage Project, was taken in 1996 by Hubble's Wide Field and Planetary Camera 2, designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The image is available online at http://heritage.stsci.edu , http://oposite.stsci.edu/pubinfo/pr/2002/12 orhttp://www.jpl.nasa.gov/images/wfpc . On the top right of the image is a source of its artistic likeness, a network of nebulous filaments surrounding the Wolf-Rayet star. This type of rare star is characterized by an exceptionally vigorous 'wind' of charged particles. The shock of the wind colliding with the surrounding gas causes the gas to glow. The Wolf-Rayet star is part of N44C, a nebula of glowing hydrogen gas surrounding young stars in the Large Magellanic Cloud. Visible from the Southern Hemisphere, the Large Magellanic Cloud is a small companion galaxy to the Milky Way. What makes N44C peculiar is the temperature of the star that illuminates it. The most massive stars -- those that are 10 to 50 times more massive than the Sun -- have maximum temperatures of 30,000 to 50,000 degrees Celsius (54,000 to 90,000 degrees Fahrenheit). The temperature of this star is about 75,000 degrees Celsius (135,000 degrees Fahrenheit). This unusually high temperature may be due to a neutron star or black hole that occasionally produces X-rays but is now inactive. N44C is part of a larger complex that includes young, hot, massive stars, nebulae, and a 'superbubble' blown out by multiple supernova explosions. Part of the superbubble is seen in red at the very bottom left of the Hubble image. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt

  3. Complex molecules in the Orion Kleinmann-Low nebula

    Directory of Open Access Journals (Sweden)

    Despois D.

    2014-02-01

    Full Text Available In the framework of the delivery to the early Earth of extraterrestrial molecules, we have studied complex molecular species toward the Orion Kleinmann-Low nebula. This nebula is rich in molecules as well as in nascent stars and planetary systems. We focus here on HCOOCH3, CH3OCH3 and deuterated methanol. Upper limits on species of prebiotic interest like glycine were also obtained.

  4. Abundances and morphology in planetary nebulae

    NARCIS (Netherlands)

    Pottasch, [No Value; Kastner, JH; Soker, N; Rappaport, SA

    2000-01-01

    The abundances of 16 well studied have been determined. New ISO measurements have been combined with optical and ultraviolet data from the literature, in an attempt to obtain accurate values. Only He, O, C, N, Ne, Ar, and S are considered. High values of N/O are sometimes, but not always, found in

  5. High dispersion spectra for planetary nebula studies

    OpenAIRE

    Lawrence H. Aller; Siek Hyung

    2002-01-01

    Mapas de alta resoluci on en radio, im agenes directas con el Telescopio Espacial Hubble y observaciones con grandes telescopios con optica adaptiva muestran que las nebulosas planetarias tienen formas extremadamente complicadas y son muy diferentes de la simplicidad con que se las imaginaba tiempo atr as. Para atender este problema, uno debe obtener espectros con alta resoluci on espacial y alta dispersi on. Tambi en se requieren largos tiempos de exposiciones, a un con telescop...

  6. The Crab Nebula

    International Nuclear Information System (INIS)

    Mitton, S.

    1979-01-01

    The subject is covered in chapters, as follows: A.D.1054, a star explodes (historical account of observations of the supernova of which the Crab Nebula is the remnant); the telescope takes over (discovery and subsequent observation of the Crab Nebula); the message of the fiery remnant (detailed structure and its interpretation); the invisible nebula (electromagnetic radiation from the Crab Nebula and its interpretation); a beacon in the night (the discovery of pulsars, with special reference to the pulsar in the Crab Nebula; observation and theory); the strange world of a neutron star (theory, prediction and observation); magnetic fields and energy flow from the pulsar (stellar magnetosphere; luminosity of the nebula); how does the pulsar pulse (observation; models to explain beaming); outburst and aftermath (types of supernovae and their evolution; nucleosynthesis); supernovae and their remnants (account of observations since early records); the Crab Nebula and modern astronomy. (U.K.)

  7. Explicit relations in Bowen fluorescence - Applications to nebulae, the sun, Scorpius X-1, and laboratory plasmas

    Science.gov (United States)

    Kastner, S. O.; Bhatia, A. K.

    1990-01-01

    A general analysis of the fluorescent process is described which emphasizes the differing roles of escape probabilities in one-component and two-component gases, and the existence of discrete fluorescent saturation regimes. Explicit formulas are obtained and discussed for astrophysical Bowen fluorescence, as a concrete example, with applications to planetary nebulae, the solar atmosphere and the X-ray binary Sco X-1. An expression is also provided and evaluated for the profile overlap integral involved in the pumping process. A preliminary conclusion is deduced that densities in the fluorescent line-emitting regions of nebular sources may be higher than those derived from forbidden line ratios. The analysis is extended to a proposed laboratory investigation which would exploit the possibility of controlling the determining factors in the fluorescent process, i.e., O III/He II abundance ratio, optical depth, and photoexciting radiation field.

  8. Three-Dimensional Adaptive Mesh Refinement Simulations of Point-Symmetric Nebulae

    NARCIS (Netherlands)

    Rijkhorst, E.-J.; Icke, V.; Mellema, G.; Meixner, M.; Kastner, J.H.; Balick, B.; Soker, N.

    2004-01-01

    Previous analytical and numerical work shows that the generalized interacting stellar winds model can explain the observed bipolar shapes of planetary nebulae very well. However, many circumstellar nebulae have a multipolar or point-symmetric shape. With two-dimensional calculations, Icke showed

  9. Hubble Space Telescope Image of Omega Nebula

    Science.gov (United States)

    2002-01-01

    This sturning image, taken by the newly installed Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST), is an image of the center of the Omega Nebula. It is a hotbed of newly born stars wrapped in colorful blankets of glowing gas and cradled in an enormous cold, dark hydrogen cloud. The region of nebula shown in this photograph is about 3,500 times wider than our solar system. The nebula, also called M17 and the Swan Nebula, resides 5,500 light-years away in the constellation Sagittarius. The Swan Nebula is illuminated by ultraviolet radiation from young, massive stars, located just beyond the upper-right corner of the image. The powerful radiation from these stars evaporates and erodes the dense cloud of cold gas within which the stars formed. The blistered walls of the hollow cloud shine primarily in the blue, green, and red light emitted by excited atoms of hydrogen, nitrogen, oxygen, and sulfur. Particularly striking is the rose-like feature, seen to the right of center, which glows in the red light emitted by hydrogen and sulfur. As the infant stars evaporate the surrounding cloud, they expose dense pockets of gas that may contain developing stars. One isolated pocket is seen at the center of the brightest region of the nebula. Other dense pockets of gas have formed the remarkable feature jutting inward from the left edge of the image. The color image is constructed from four separate images taken in these filters: blue, near infrared, hydrogen alpha, and doubly ionized oxygen. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA.

  10. Properties of interstellar dust in reflection nebulae

    International Nuclear Information System (INIS)

    Sellgren, K.

    1988-01-01

    Observations of interstellar dust in reflection nebulae are the closest analog in the interstellar medium to studies of cometary dust in our solar system. The presence of a bright star near the reflection nebula dust provides the opportunity to study both the reflection and emission characteristics of interstellar dust. At 0.1 to 1 micrometer, the reflection nebula emission is due to starlight scattered by dust. The albedo and scattering phase function of the dust is determined from observations of the scattered light. At 50 to 200 micrometers, thermal emission from the dust in equilibrium with the stellar radiation field is observed. The derived dust temperature determines the relative values of the absorption coefficient of the dust at wavelengths where the stellar energy is absorbed and at far infrared wavelengths where the absorbed energy is reradiated. These emission mechanisms directly relate to those seen in the near and mid infrared spectra of comets. In a reflection nebula the dust is observed at much larger distances from the star than in our solar system, so that the equilibrium dust temperature is 50 K rather than 300 K. Thus, in reflection nebulae, thermal emission from dust is emitted at 50 to 200 micrometer

  11. Charge transfer in astrophysical nebulae

    International Nuclear Information System (INIS)

    Shields, G.A.

    1990-01-01

    Charge transfer has become a standard ingredient in models of ionized nebulae, supernovae remnants and active galactic nuclei. Charge transfer rate coefficients and the physics of ionized nebulae are considered. Charge transfer is applied to the ionization structure and line emission of ionized nebulae. Photoionized nebulae observations are used to test theoretical predictions of charge transfer rates. (author)

  12. Wolf-Rayet nebulae

    International Nuclear Information System (INIS)

    Chu, You-Hua

    2016-01-01

    Since the discovery of nebulae around Wolf-Rayet (WR) stars in the 1960s, it has been established that WR stars are massive stars at advanced evolutionary stages and that their surrounding nebulae result from the interactions between the stellar mass loss and the ambient interstellar medium. Surveys of WR nebulae have been made in the Galaxy, Magellanic Clouds, and other nearby galaxies in the Local Group. Some WR nebulae exhibit He II λ4686 line emission, indicating stellar effective temperatures of 90 — 100 x 10 3 K. The shocked fast stellar winds from WR nebulae have been detected in soft X-rays, but theoretical models have not been able to reproduce the observed X-ray spectral properties. Elemental abundances of WR nebulae consisting of synthesized stellar material can constrain stellar evolution models, but high-dispersion spectra are needed to kinematically separate the expanding shell of a WR nebula and the background interstellar medium for accurate abundance analyses. (paper)

  13. GIANT Hα NEBULA SURROUNDING THE STARBURST MERGER NGC 6240

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Yagi, Masafumi; Komiyama, Yutaka; Kashikawa, Nobunari [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Ohyama, Youichi [Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No.1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C. (China); Tanaka, Hisashi [Department of Physical Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Okamura, Sadanori, E-mail: yoshidam@hiroshima-u.ac.jp [Department of Advanced Sciences, Faculty of Science and Engineering, Hosei University, Koganei, Tokyo 184-8584 (Japan)

    2016-03-20

    We revealed the detailed structure of a vastly extended Hα-emitting nebula (“Hα nebula”) surrounding the starburst/merging galaxy NGC 6240 by deep narrow-band imaging observations with the Subaru Suprime-Cam. The extent of the nebula is ∼90 kpc in diameter and the total Hα luminosity amounts to L{sub Hα} ≈ 1.6 × 10{sup 42} erg s{sup −1}. The volume filling factor and the mass of the warm ionized gas are ∼10{sup −4}–10{sup −5} and ∼5 × 10{sup 8} M{sub ⊙}, respectively. The nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots. We found that there is a tight spatial correlation between the Hα nebula and the extended soft-X-ray-emitting gas, both in large and small scales. The overall morphology of the nebula is dominated by filamentary structures radially extending from the center of the galaxy. A large-scale bipolar bubble extends along the minor axis of the main stellar disk. The morphology strongly suggests that the nebula was formed by intense outflows—superwinds—driven by starbursts. We also found three bright knots embedded in a looped filament of ionized gas that show head-tail morphologies in both emission-line and continuum, suggesting close interactions between the outflows and star-forming regions. Based on the morphology and surface brightness distribution of the Hα nebula, we propose the scenario that three major episodes of starburst/superwind activities, which were initiated ∼10{sup 2} Myr ago, formed the extended ionized gas nebula of NGC 6240.

  14. A 'variable' stellar object in a variable blue nebula V-V 1-7

    International Nuclear Information System (INIS)

    Rao, N.K.; Gilra, D.P.

    1981-01-01

    V-V 1-7 is supposed to be one of the few planetary nebulae with Ao central stars and was included in the planetary-nebula catalogue as PK 235 + 1 0 1. The nebula was seen on the blue Palomar Observatory Sky Survey (POSS) print but not on the red print; as a result it was thought that it might be a reflection nebula. However, the symmetry of the nebula around the central star (HD 62001), and also the ultraviolet photometric variability of this central star led others to suggest that the nebula might be a nova shell. Subsequently it was found that the nebula V-V 1-7 has disappeared. It is not seen on any direct plate known to us except the POSS blue plate. In this paper the disappearance is reported (along with the nebula) of a stellar object, which appears within the 'nebular shell' of V-V 1-7 on the POSS blue plate, but not on the red plate. (author)

  15. The Crab Nebula flaring activity

    Directory of Open Access Journals (Sweden)

    G. Montani

    2014-12-01

    Full Text Available The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼1015 cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼109, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  16. Cool gaseous nebulae

    CERN Document Server

    Shaver, P A; Pottasch, S R

    1979-01-01

    The electron temperatures of diffuse gaseous nebulae have long been thought to be close to 10/sup 4/K. Much lower temperatures were derived from some of the early radio continuum and recombination line work, but these were generally considered to be wrong for a variety of reasons. While there is little doubt that the bright nebulae do indeed have temperatures of approximately 8000-9000K, there are strong indications that some nebulae of lower densities have much lower temperatures, nebulae were made in order to determine electron temperatures in the absence of such effects as collisional de-excitation, stimulated emission, and pressure broadening. Several of these nebulae have been found to have temperatures below 5000K and for two of them which are discussed (RCW94 and G339.1-0.2) absolute upper limits of approximately 4700 K are imposed by the line widths alone. (11 refs).

  17. Models for the structure and origin of bipolar nebulae

    International Nuclear Information System (INIS)

    Morris, M.

    1981-01-01

    The appearance of bipolar nebulae-symmetric reflection nebulae centered on evolved, mass-losing stars-can most simply be accounted for in terms of an axisymmetric distribution of outflowing dust in which the dust is concentrated towards an equatorial plane and declines monotonically with latitude above that plane. The symmetrically placed ''horns'' that can be seen radiating out of some bipolar nebulae, notably GL 2688, are a natural consequence of such a dust distribution if, at some latitude, the radial optical depth to starlight falls rapidly below unity. Several models of bipolar nebulae are presented. These structural models for bipolar nebulae lead in turn to an investigation of how such a geometry might arise. Although nonradial pulsation, rotationally forced mass ejection by a single star, and mass loss from a common envelope binary are all considered, the most attractive origin for bipolar nebulae is a binary star system in which the primary is evolving up the red giant branch to the point at which its radius approaches its tidal radius. If this occurs before corotation of the primary with the secondary's orbit can be achieved, then matter from the primary's enveloped can be gravitationally ejected from the system by the secondary, the ejected material being concentrated toward the system's equatorial plane. Numerical models of this phenomenon show that gravitational ejection from an asynchronous binary system easily leads to terminal outflow velocities in the observed range (20--50 km s -1 ), and that the rate of mass loss and the time scale over which the mass ejection takes place are consistent with observations if the particle density in the outer layers of the primary's atmosphere from which the material is extracted is in the range 10 14 --10 15 cm -3 . If this hypothesis is applicable, bipolar nebulae will probably become planetary nebulae, as previously suggested on observational grounds

  18. Abundance of carbon and magnesium in the Orion nebula

    International Nuclear Information System (INIS)

    Perinotto, M.; Patriarchi, P.

    1980-01-01

    The Orion nebula has been observed in two positions with IUE (International Ultraviolet Explorer) in the low-resolution mode (approx.7 A) and in the spectral range 1150--3200 A. Emission lines of C II], C III], [O II], and He I have been measured and used to determine what is probably the first reliable abundance of carbon in H II regions. The logarithmic total abundance of carbon is found to be 8.4 close to the solar value. In contrast with the situation in the planetary nebula of similar excitation, IC 418, where the resonance Mg II lambda2800 line is observed to be relatively strong, in the Orion nebula the lambda2800 line is not detectable. an upper limit for the magnesium abundance of the order of 10 times smaller than in the Sun is suggested

  19. Kinetic model of ammonia synthesis in the solar nebula

    Science.gov (United States)

    Norris, T. L.

    1980-03-01

    Kinetic model of ammonia formation by iron catalysis in the primordial solar nebula is developed. The maximum time to reach equilibrium concentration is determined for various temperatures between 1000 and 200 K on the basis of reaction rates derived from industrial data on iron catalysts for ammonia. Application of the method for calculating the equilibrium time to an arbitrary nebula cooling model which maximizes the time available for ammonia synthesis results in an upper limit of 3% of the equilibrium value to the proportion of nitrogen in the form of ammonia at the time of planetary accretion, with ammonia abundance decreasing with distance from the sun. It is concluded that kinetic rather than equilibrium considerations control the abundance of ammonia in the solar nebula, and implications of the dominance of nitrogen for the evolution of the atmospheres of the terrestrial and Jovian planets and the composition of comets are indicated.

  20. The surprising Crab pulsar and its nebula: a review.

    Science.gov (United States)

    Bühler, R; Blandford, R

    2014-06-01

    The Crab nebula and its pulsar (referred to together as 'the Crab') have historically played a central role in astrophysics. True to this legacy, several unique discoveries have been made recently. The Crab was found to emit gamma-ray pulsations up to energies of 400 GeV, beyond what was previously expected from pulsars. Strong gamma-ray flares, of durations of a few days, were discovered from within the nebula, while the source was previously expected to be stable in flux on these time scales. Here we review these intriguing and suggestive developments. In this context we give an overview of the observational properties of the Crab and our current understanding of pulsars and their nebulae.

  1. Non-planetary Science from Planetary Missions

    Science.gov (United States)

    Elvis, M.; Rabe, K.; Daniels, K.

    2015-12-01

    Planetary science is naturally focussed on the issues of the origin and history of solar systems, especially our own. The implications of an early turbulent history of our solar system reach into many areas including the origin of Earth's oceans, of ores in the Earth's crust and possibly the seeding of life. There are however other areas of science that stand to be developed greatly by planetary missions, primarily to small solar system bodies. The physics of granular materials has been well-studied in Earth's gravity, but lacks a general theory. Because of the compacting effects of gravity, some experiments desired for testing these theories remain impossible on Earth. Studying the behavior of a micro-gravity rubble pile -- such as many asteroids are believed to be -- could provide a new route towards exploring general principles of granular physics. These same studies would also prove valuable for planning missions to sample these same bodies, as techniques for anchoring and deep sampling are difficult to plan in the absence of such knowledge. In materials physics, first-principles total-energy calculations for compounds of a given stoichiometry have identified metastable, or even stable, structures distinct from known structures obtained by synthesis under laboratory conditions. The conditions in the proto-planetary nebula, in the slowly cooling cores of planetesimals, and in the high speed collisions of planetesimals and their derivatives, are all conditions that cannot be achieved in the laboratory. Large samples from comets and asteroids offer the chance to find crystals with these as-yet unobserved structures as well as more exotic materials. Some of these could have unusual properties important for materials science. Meteorites give us a glimpse of these exotic materials, several dozen of which are known that are unique to meteorites. But samples retrieved directly from small bodies in space will not have been affected by atmospheric entry, warmth or

  2. Dark nebulae, dark lanes, and dust belts

    CERN Document Server

    Cooke, Antony

    2012-01-01

    As probably the only book of its type, this work is aimed at the observer who wants to spend time with something less conventional than the usual fare. Because we usually see objects in space by means of illumination of one kind or another, it has become routine to see them only in these terms. However, part of almost everything that we see is the defining dimension of dark shading, or even the complete obscuration of entire regions in space. Thus this book is focused on everything dark in space: those dark voids in the stellar fabric that mystified astronomers of old; the dark lanes reported in many star clusters; the magical dust belts or dusty regions that have given so many galaxies their identities; the great swirling 'folds' that we associate with bright nebulae; the small dark feature detectable even in some planetary nebulae; and more. Many observers pay scant attention to dark objects and details. Perhaps they are insufficiently aware of them or of the viewing potential they hold, but also it may be...

  3. Gas capture and rare gas retention by accreting planets in the solar nebula

    International Nuclear Information System (INIS)

    Mizuno, H.; Nakazawa, K.; Hayashi, C.

    1982-01-01

    In this paper, the physico-chemical effects of the nebula gas on the planets are reviewed from a standpoint of planetary formation in the solar nebula. The proto-Earth growing in the nebula was surrounded by a primordial atmosphere with a solar chemical composition and solar isotopic composition. When the mass of the proto-Earth was greater than 0.3 times the present Earth mass, the surface was molten because of the blanketing effect of the atmosphere. Therefore, the primordial rare gases contained in the primordial atmosphere dissolved into the molten Earth material without fractionation and in particular the dissolved neon is expected to be conserved in the present Earth material. Hence, if dissolved neon with a solar isotopic ratio is discovered in the Earth material, it will indicate that the Earth was formed in the nebula and that the dissolved rare gases were one of the sources which degassed to form the present atmosphere. (author)

  4. Structure of the solar nebula, growth and decay of magnetic fields and effects of magnetic and turbulent viscosities on the nebula

    International Nuclear Information System (INIS)

    Hayashi, Chushiro

    1982-01-01

    First, distributions of surface densities of dust materials and gases in a preplanetary solar nebula, which give a good fit to the distribution of the planetary mass, are presented and the over-all structure of this nebula, which is in thermal and gravitational equilibrium, is studied. Second, in order to see magnetic effect on the structure, electric conductivity of a gas ionized by cosmic rays and radioactivities contained in dust grains is estimated for each region of the nebula and, then, the growth and decay of seed magnetic fields, which are due to differential rotation of the nebula and to the Joule dissipation, respectively, are calculated. The results indicate that, in regions of the terrestrial planets, magnetic fields decay much faster than they grow and magnetic effects can be ignored, except for the outermost layers of very low density. This is not the case for regions of Uranus and Neptune where magnetic fields can be amplified to considerable extents. Third, the transport of angular momentum due to magnetic and mechanical turbulent viscosities and the resultant redistribution of surface density in the nebula are investigated. The results show that the density redistribution occurs, in general, in a direction to attain a distribution of surface density which has nearly the same ν-dependence as that obtained from the present distribution of the planetary mass. This redistribution seems to be possible if it occurs at a formation stage of the nebula where the presence of large viscosities is expected. Finally, a comment is given on the initial condition of a collapsing interstellar cloud from which the solar nebula is formed at the end of the collapse. (author)

  5. Infrared nebula in the Chamaeleon T association

    International Nuclear Information System (INIS)

    Schwartz, R.D.; Henize, K.G.

    1983-01-01

    Data are tabulated for seven nebulae in the Chamaeleon T association. Three, which are large and clearly related to illuminating stars, appear to be typical reflection nebulae. Three are small wisps attached to stars and are probably cometary-type reflection nebulae. The remaining nebula is a triangular wisp having an unusually red spectral energy distribution and showing no illuminating star on visual wavelength photographs. The western tip of this nebula coincides closely with the position of a recently reported infrared source. The nebula is probably one lobe of a bipolar nebula

  6. Modeling radio circular polarization in the Crab nebula

    Science.gov (United States)

    Bucciantini, N.; Olmi, B.

    2018-03-01

    In this paper, we present, for the first time, simulated maps of the circularly polarized synchrotron emission from the Crab nebula, using multidimensional state of the art models for the magnetic field geometry. Synchrotron emission is the signature of non-thermal emitting particles, typical of many high-energy astrophysical sources, both Galactic and extragalactic ones. Its spectral and polarization properties allow us to infer key information on the particles distribution function and magnetic field geometry. In recent years, our understanding of pulsar wind nebulae has improved substantially thanks to a combination of observations and numerical models. A robust detection or non-detection of circular polarization will enable us to discriminate between an electron-proton plasma and a pair plasma, clarifying once for all the origin of the radio emitting particles, setting strong constraints on the pair production in pulsar magnetosphere, and the role of turbulence in the nebula. Previous attempts at measuring the circular polarization have only provided upper limits, but the lack of accurate estimates, based on reliable models, makes their interpretation ambiguous. We show here that those results are above the expected values, and that current polarimetric techniques are not robust enough for conclusive result, suggesting that improvements in construction and calibration of next generation radio facilities are necessary to achieve the desired sensitivity.

  7. Planetary Magnetism

    Science.gov (United States)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  8. Kinematics and chemistry of planetary nebulae with water maser emission /

    OpenAIRE

    Tafoya Martínez, Daniel sustentante.

    2009-01-01

     tesis que para obtener el grado de Doctor en Ciencias de la Tierra, presenta Daniel Tafoya Martínez ; asesor Yolanda Gómez Castellanos, Ninesh A. Patel. XXV, 116 páginas : ilustraciones. Doctorado en Ciencias de la Tierra UNAM, Centro de Ciencias de la Atmósfera, 2009

  9. Planetary Nebulae as kinematic and dynamical tracers of galaxy halos

    NARCIS (Netherlands)

    Coccato, Lodovico; Napolitano, Nicola; Arnaboldi, Magda; Cortesi, Arianna; Romanowsky, Aaron; Gerhard, Ortwin; Merrifield, Michael; Kuijken, Konrad; Freeman, Ken; Douglas, Nigel

    2015-01-01

    The kinematics and dynamical properties of galaxy halos are difficult to measure, given the faint stellar surface brightness that characterizes those regions. Gas-rich systems such as spiral galaxies can be probed using the radio emission of their gas component. Early type galaxies contain less gas,

  10. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Naumann-Godo, M.; Pierbattista, M.; Tibaldo, L.

    2011-01-01

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10 15 electron volts) electrons in a region smaller than 1.4 * 10 -2 parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory. (authors)

  11. The Toby Jug nebula (IC 2220): a bipolar and biconical nebula

    International Nuclear Information System (INIS)

    Perkins, H.G.; King, D.J.; Scarrott, S.M.

    1981-01-01

    An optical linear polarization map of IC 2220, the nebula surrounding the cool red giant HD 65750, is presented. The nebula appears to be bipolar and biconical in structure. The mass of the nebula is estimated to be 0.01 solar mass and is consistent with the nebula being formed from the current mass loss stage of the central star. (author)

  12. Optical polarization in the Serpens Nebula

    Energy Technology Data Exchange (ETDEWEB)

    King, D.J.; Scarrott, S.M. (Durham Univ. (UK). Dept. of Physics); Taylor, K.N.R. (New South Wales Univ., Kensington (Australia). School of Physics)

    1983-03-01

    Optical polarization maps are presented that indicate that the object is a reflection nebula illuminated by a highly obscured star that is itself seen through magnetically aligned grains. It is proposed that the dust grains overlying the central region of the nebula including the illuminating star are aligned by the local galactic magnetic field that permeates the dark cloud in which the nebula is situated. The formation of the nebula is discussed.

  13. Planetary Magnetism

    International Nuclear Information System (INIS)

    Russell, C.T.

    1980-01-01

    Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io

  14. Contraction of the solar nebula

    International Nuclear Information System (INIS)

    Rawal, J.J.

    1984-01-01

    The concept of Roche limit is applied to the Laplacian theory of the origin of the solar system to study the contraction of a spherical gas cloud (solar nebula). In the process of contraction of the solar nebula, it is assumed that the phenomenon of supersonic turbulent convection is operative and brings about the halt at various stages of contraction. It is found that the radius of the contracting solar nebula follows the Titius-Bode law. The consequences of the relation are also discussed. The aim is to attempt to explain, on the basis of the concept of Roche limit, the distribution of planets in the solar system and try to understand the physics underlying it. (Auth.)

  15. Discovery of a Circumstellar Disk in the Lagoon Nebula

    Science.gov (United States)

    1997-04-01

    Circumstellar disks of gas and dust play a crucial role in the formation of stars and planets. Until now, high-resolution images of such disks around young stars within the Orion Nebula obtained with the Hubble Space Telescope (HST) constituted the most direct proof of their existence. Now, another circumstellar disk has been detected around a star in the Lagoon Nebula - also known as Messier 8 (M8) , a giant complex of interstellar gas and dust with many young stars in the southern constellation of Sagittarius and four times more distant than the Orion Nebula. The observations were carried out by an international team of scientists led by Bringfried Stecklum (Thüringer Landessternwarte, Tautenburg, Germany) [1] who used telescopes located at the ESO La Silla observatory and also observations from the HST archive. These new results are paving the road towards exciting research programmes on star formation which will become possible with the ESO Very Large Telescope. The harsh environment of circumstellar disks The existence of circumstellar disks has been inferred from indirect measurements of young stellar objects, such as the spectral energy distribution, the analysis of the profiles of individual spectral lines and measurements of the polarisation of the emitted light [2]. Impressive images of such disks in the Orion Nebula, known as proplyds (PROto-PLanetarY DiskS), have been obtained by the HST during the recent years. They have confirmed the interpretation of previous ground-based emission-line observations and mapping by radio telescopes. Moreover, they demonstrated that those disks which are located close to hot and massive stars are subject to heating caused by the intense radiation from these stars. Subsequently, the disks evaporate releasing neutral gas which streams off. During this process, shock fronts (regions with increased density) with tails of ionised gas result at a certain distance between the disk and the hot star. These objects appear on

  16. Spectroscopy of the ringlike nebula toward the open cluster NGC 3572

    Science.gov (United States)

    Noumaru, Junichi; Ogura, Katsuo

    1993-11-01

    Low-dispersion spectroscopy has been obtained for the ringlike nebula which Phelps and Janes (1991) found in the direction of the young open cluster NGC 3572 and suspected as a planetary nebula. Some nearby nebulosities have also been observed. Analyses of these data indicate that all of them, including the NGC 3572 ring, are H II regions. Morphological considerations of the region show that the nearby nebulosities are bright rims which are associated with the H II region BBW 342 and are partly hidden by the obscuring matter lying on this side. The NGC 3572 ring could be of the same nature. However, as the alternative interpretation, it could be a ring nebula (probably a wind-blown bubble) around a massive star (WR/Of star or LBV).

  17. Planetary Rings

    Science.gov (United States)

    Tiscareno, Matthew S.

    Planetary rings are the only nearby astrophysical disks and the only disks that have been investigated by spacecraft (especially the Cassini spacecraft orbiting Saturn). Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 10- 7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close range and in real time in planetary rings.We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The A, B, and C rings of Saturn, plus the Cassini Division, comprise our solar system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are found both at Uranus (where they comprise the main rings entirely) and at Saturn (where they are embedded in the broad disk) and are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally confined arcs at Neptune, Saturn, and Jupiter. Finally, every known ring system includes a substantial component of diffuse dusty rings.Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of

  18. Planetary Society

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    Carl Sagan, Bruce Murray and Louis Friedman founded the non-profit Planetary Society in 1979 to advance the exploration of the solar system and to continue the search for extraterrestrial life. The Society has its headquarters in Pasadena, California, but is international in scope, with 100 000 members worldwide, making it the largest space interest group in the world. The Society funds a var...

  19. Planetary atomspheres

    International Nuclear Information System (INIS)

    Lal, D.; Rao, M.N.

    1986-01-01

    Salient features of the atmosheres of Venus and Mars are described and compared with those of the earth. Their temperature profiles are given. Degassing of planetary interiors by volcanic and plate tectonic processes is described. Noble gas abundances in the atmospheres of these planets are compared. Information provided by Pioneer, Venera space probes and the Viking-landers on Mars is studied. (B.G.W.)

  20. Planetary engineering

    Science.gov (United States)

    Pollack, James B.; Sagan, Carl

    1991-01-01

    Assuming commercial fusion power, heavy lift vehicles and major advances in genetic engineering, the authors survey possible late-21st century methods of working major transformations in planetary environments. Much more Earthlike climates may be produced on Mars by generating low freezing point greenhouse gases from indigenous materials; on Venus by biological conversion of CO2 to graphite, by canceling the greenhouse effect with high-altitude absorbing fine particles, or by a sunshield at the first Lagrangian point; and on Titan by greenhouses and/or fusion warming. However, in our present state of ignorance we cannot guarantee a stable endstate or exclude unanticipated climatic feedbacks or other unintended consequences. Moreover, as the authors illustrate by several examples, many conceivable modes of planetary engineering are so wasteful of scarce solar system resources and so destructive of important scientific information as to raise profound ethical issues, even if they were economically feasible, which they are not. Global warming on Earth may lead to calls for mitigation by planetary engineering, e.g., emplacement and replenishment of anti-greenhouse layers at high altitudes, or sunshields in space. But here especially we must be concerned about precision, stability, and inadvertent side-effects. The safest and most cost-effective means of countering global warming - beyond, e.g., improved energy efficiency, CFC bans and alternative energy sources - is the continuing reforestation of approximately 2 times 107 sq km of the Earth's surface. This can be accomplished with present technology and probably at the least cost.

  1. Planetary engineering

    Science.gov (United States)

    Pollack, James B.; Sagan, Carl

    Assuming commercial fusion power, heavy lift vehicles and major advances in genetic engineering, the authors survey possible late-21st century methods of working major transformations in planetary environments. Much more Earthlike climates may be produced on Mars by generating low freezing point greenhouse gases from indigenous materials; on Venus by biological conversion of CO2 to graphite, by canceling the greenhouse effect with high-altitude absorbing fine particles, or by a sunshield at the first Lagrangian point; and on Titan by greenhouses and/or fusion warming. However, in our present state of ignorance we cannot guarantee a stable endstate or exclude unanticipated climatic feedbacks or other unintended consequences. Moreover, as the authors illustrate by several examples, many conceivable modes of planetary engineering are so wasteful of scarce solar system resources and so destructive of important scientific information as to raise profound ethical issues, even if they were economically feasible, which they are not. Global warming on Earth may lead to calls for mitigation by planetary engineering, e.g., emplacement and replenishment of anti-greenhouse layers at high altitudes, or sunshields in space. But here especially we must be concerned about precision, stability, and inadvertent side-effects. The safest and most cost-effective means of countering global warming - beyond, e.g., improved energy efficiency, CFC bans and alternative energy sources - is the continuing reforestation of approximately 2 times 107 sq km of the Earth's surface. This can be accomplished with present technology and probably at the least cost.

  2. A study of the compact nebulae VV 8 and M3-27

    International Nuclear Information System (INIS)

    Adams, T.F.

    1975-01-01

    New photometric observations of the lines and continuum in the compact nebulae VV 8 and M3-27 are presented. The data for VV 8 are very similar to those obtained by O'Dell nearly 10 years ago. Both nebulae have high electron densities and are self-absorbed in Hα. Parameters describing the physical conditions are estimated using the observed Balmer and O iii line strengths. By comparing the observations with suitable models for young planetary nebulae, the abundances of helium, oxygen, and neon are shown to be normal. The N ii lines are stronger than predicted. The continuum in M3-27 is shown to be in good agreement with theory, while the continuum in VV 8 in the visible and infrared is much brighter than predicted. The similarity between the line spectra and inferred properties of the nebulae suggests that the optical continuum in VV 8 is unrelated to the nebula, and may come from a late-type companion in a binary. Serious difficulties remain, however, concerning the absolute magnitude and color of the companion in the binary model. Some implications of Zipoy's shell star model are also examined

  3. Scaled Eagle Nebula Experiments on NIF

    Energy Technology Data Exchange (ETDEWEB)

    Pound, Marc W. [Univ. of Maryland, College Park, MD (United States)

    2017-03-28

    We performed scaled laboratory experiments at the National Ignition Facility laser to assess models for the creation of pillar structures in star-forming clouds of molecular hydrogen, in particular the famous Pillars of the Eagle Nebula. Because pillars typically point towards nearby bright ultraviolet stars, sustained directional illumination appears to be critical to pillar formation. The experiments mock up illumination from a cluster of ultraviolet-emitting stars, using a novel long duration (30--60 ns), directional, laser-driven x-ray source consisting of multiple radiation cavities illuminated in series. Our pillar models are assessed using the morphology of the Eagle Pillars observed with the Hubble Space Telescope, and measurements of column density and velocity in Eagle Pillar II obtained at the BIMA and CARMA millimeter wave facilities. In the first experiments we assess a shielding model for pillar formation. The experimental data suggest that a shielding pillar can match the observed morphology of Eagle Pillar II, and the observed Pillar II column density and velocity, if augmented by late time cometary growth.

  4. The western Veil nebula (Image)

    Science.gov (United States)

    Glenny, M.

    2009-12-01

    The western Veil nebula in Cygnus. 15-part mosaic by Mike Glenny, Gloucestershire, taken over several months mostly in the autumn of 2008. 200mm LX90/f10 autoguided, Meade UHC filter, 0.3xFR/FF, Canon 20Da DSLR. Exposures each typically 10x360 secs at ISO1600, processed in Registax4, PixInsight (for flat field correction) & Photoshop CS.

  5. Planetary geology

    CERN Document Server

    Gasselt, Stephan

    2018-01-01

    This book provides an up-to-date interdisciplinary geoscience-focused overview of solid solar system bodies and their evolution, based on the comparative description of processes acting on them. Planetary research today is a strongly multidisciplinary endeavor with efforts coming from engineering and natural sciences. Key focal areas of study are the solid surfaces found in our Solar System. Some have a direct interaction with the interplanetary medium and others have dynamic atmospheres. In any of those cases, the geological records of those surfaces (and sub-surfaces) are key to understanding the Solar System as a whole: its evolution and the planetary perspective of our own planet. This book has a modular structure and is divided into 4 sections comprising 15 chapters in total. Each section builds upon the previous one but is also self-standing. The sections are:  Methods and tools Processes and Sources  Integration and Geological Syntheses Frontiers The latter covers the far-reaching broad topics of exo...

  6. The Minimum-Mass Surface Density of the Solar Nebula using the Disk Evolution Equation

    Science.gov (United States)

    Davis, Sanford S.

    2005-01-01

    The Hayashi minimum-mass power law representation of the pre-solar nebula (Hayashi 1981, Prog. Theo. Phys.70,35) is revisited using analytic solutions of the disk evolution equation. A new cumulative-planetary-mass-model (an integrated form of the surface density) is shown to predict a smoother surface density compared with methods based on direct estimates of surface density from planetary data. First, a best-fit transcendental function is applied directly to the cumulative planetary mass data with the surface density obtained by direct differentiation. Next a solution to the time-dependent disk evolution equation is parametrically adapted to the planetary data. The latter model indicates a decay rate of r -1/2 in the inner disk followed by a rapid decay which results in a sharper outer boundary than predicted by the minimum mass model. The model is shown to be a good approximation to the finite-size early Solar Nebula and by extension to extra solar protoplanetary disks.

  7. Plerions and pulsar-powered nebulae

    OpenAIRE

    Gaensler, Bryan

    2000-01-01

    In this brief review, I discuss recent developments in the study of pulsar-powered nebulae ("plerions"). The large volume of data which has been acquired in recent years reveals a diverse range of observational properties, demonstrating how differing environmental and pulsar properties manifest themselves in the resulting nebulae.

  8. A Smoking Gun in the Carina Nebula

    Science.gov (United States)

    Hamaguchi, Kenji; Corcoran, Michael F.; Ezoe, Yuichiro; Townsley, Leisa; Broos, Patrick; Gruendl, Robert; Vaidya, Kaushar; White, Stephen M.; Petre, Rob; Chu, You-Hua

    2009-01-01

    The Carina Nebula is one of thc youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for approx.30 years. The soft X-ray spectrum. consistent with kT approx.130 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicate that it is a, approx. 10(exp 6)-year-old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitor of the neutron star and massive stars in the Carina Nebula, in particular (eta)Car, are coeval. This result demonstrates that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star would be responsible for remnants of high energy activity seen in multiple wavelengths.

  9. A dam around the Water Fountain Nebula? The dust shell of IRAS16342-3814 spatially resolved with VISIR/VLT

    NARCIS (Netherlands)

    Verhoelst, T.; Waters, L.B.F.M.; Verhoeff, A.; Dijkstra, C.; van Winckel, H.; Pel, J.W.; Peletier, R.F.

    2009-01-01

    Context. Bipolar morphologies in planetary nebulae (PNe) are believed to be closely linked to binary central stars. Either by collimating a fast stellar wind or by driving a jet via accretion in the central system, dusty torii or stable disks may be crucial ingredients for the shaping of PNe. Aims.

  10. A dam around the Water Fountain Nebula? The dust shell of IRAS16342-3814 spatially resolved with VISIR/VLT

    NARCIS (Netherlands)

    Verhoelst, T.; Waters, L. B. F. M.; Verhoeff, A.; Dijkstra, C.; Van Winckel, H.; Pel, J. W.; Peletier, R. F.

    Context. Bipolar morphologies in planetary nebulae (PNe) are believed to be closely linked to binary central stars. Either by collimating a fast stellar wind or by driving a jet via accretion in the central system, dusty torii or stable disks may be crucial ingredients for the shaping of PNe. Aims.

  11. NIF Discovery Science Eagle Nebula

    Science.gov (United States)

    Kane, Jave; Martinez, David; Pound, Marc; Heeter, Robert; Casner, Alexis; Villette, Bruno; Mancini, Roberto

    2017-10-01

    The University of Maryland and and LLNL are investigating the origin and dynamics of the famous Pillars of the Eagle Nebula and similar parsec-scale structures at the boundaries of HII regions in molecular hydrogen clouds. The National Ignition Facility (NIF) Discovery Science program Eagle Nebula has performed NIF shots to study models of pillar formation. The shots feature a new long-duration x-ray source, in which multiple hohlraums mimicking a cluster of stars are driven with UV light in series for 10 to 15 ns each to create a 30 to 60 ns output x-ray pulse. The source generates deeply nonlinear hydrodynamics in the Eagle science package, a structure of dense plastic and foam mocking up a molecular cloud containing a dense core. Omega EP and NIF shots have validated the source concept, showing that earlier hohlraums do not compromise later ones by preheat or by ejecting ablated plumes that deflect later beams. The NIF shots generated radiographs of shadowing-model pillars, and also showed evidence that cometary structures can be generated. The velocity and column density profiles of the NIF shadowing and cometary pillars have been compared with observations of the Eagle Pillars made at the millimeter-wave BIMA and CARMA observatories. Prepared by LLNL under Contract DE-AC52-07NA27344.

  12. Nebulae and how to observe them

    CERN Document Server

    Coe, Steven

    2007-01-01

    This "Astronomers' Observing Guides" are designed for practical amateur astronomers who not only want to observe, but want to know the details of exactly what they are looking at. Nebulae are the places where the stars are born. For amateur astronomers, the many different kinds of nebulae vary from "easy" targets that can be seen with modest equipment under mediocre skies, to "challenging" objects that require experienced observers, large telescopes and excellent seeing. The concept of the book - and of the series - is to present an up-to-date detailed description and categorisation (part one); and then (part two) to consider how best to successfully observe and record the large range of astronomical objects that fall under the general heading of "nebulae". "Nebulae, and How to Observe Them" is a mine of information for all levels of amateur observers, from the beginner to the experienced.

  13. Is gas in the Orion nebula depleted

    International Nuclear Information System (INIS)

    Aiello, S.; Guidi, I.

    1978-01-01

    Depletion of heavy elements has been recognized to be important in the understanding of the chemical composition of the interstellar medium. This problem is also relevant to the study of H II regions. In this paper the gaseous depletion in the physical conditions of the Orion nebula is investigated. The authors reach the conclusion that very probably no depletion of heavy elements, due to sticking on dust grains, took place during the lifetime of the Orion nebula. (Auth.)

  14. Planetary Data System (PDS)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Planetary Data System (PDS) is an archive of data products from NASA planetary missions, which is sponsored by NASA's Science Mission Directorate. We actively...

  15. The simplest models of the reflection nebulae

    International Nuclear Information System (INIS)

    Voshchinnikov, N.V.

    1977-01-01

    Some models of the reflection nebulue have been considered. The (U-B), (B-V) and (V-R) colors and the U, B, V and R polarization have been calculated for a model of a reflection nebula associated with a large dust cloud. For the cases in which the illuminating star is far from the surface of the cloud, the form of the nebula has been considered to be spherical. If the star is close to the surface of the cloud, a part of the nebura boundary has been considered to be flat. Single scattering within the homogeneous nebula has been assumed. All the calculations use the scattering by spheres as given by the Mie's theory. The effect of variations of chemical composition and size distribution function of the grains and the position of the illuminating star has been examined. Comparison of the theoretical results with the observations of the Merope nebula shows that the dirty ice grains with the refraction index m=1.30-0.02i and size parameter asub(o)=0.5μ represent satisfactorily the observation if the star is embedded 0.7 pc behind the front surface of the nebula

  16. Lunar occultation observations of the Crab Nebula

    International Nuclear Information System (INIS)

    Maloney, F.P.

    1977-01-01

    Three lunar of occultations of the Crab Nebula were observed, two at 114 MHz and one at 26.3 MHz, during the 1974 series of events. The higher frequency observations were deconvolved of diffraction effects to yield four strip integrated brightness profiles of the Nebula, with an effective resolution of 30 arc-seconds. These four profiles were Fourier inverted and cleaned of sidelobe structure to synthesize a two-dimensional map of the Nebula. At 114 MHz, the Nebula is composed of a broad envelope of emission which contains several smaller sources. The attenuation of the low radio frequency radiation by the thermal hydrogen in the filaments is considered as a possible mechanism to explain these new data. The 26.3 MHz observations indicate the presence of a bright, localized source containing greater than 80% of the flux of the Nebula. The position of the source is confined by the data to a narrow strip centered at the pulsar position. Both sets of data are compared with past occultation observations

  17. Emission lines of [K V] in the optical spectra of gaseous nebulae.

    Science.gov (United States)

    Keenan, Francis P; Aller, Lawrence H; Espey, Brian R; Exter, Katrina M; Hyung, Siek; Keenan, Michael T C; Pollacco, Don L; Ryans, Robert S I

    2002-04-02

    Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 A)/I(4163.3 A) as a function of electron density (N(e)). This ratio is found to be very sensitive to changes in N(e) over the density range 10(3) to 10(6) cm(-3), but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical N(e) diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne iv], formed in the same region of the nebula as [K v]. This observation provides observational support for the accuracy of the theoretical [K v] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope, reveals that the [K v] 4122.6 A line in this object is badly blended with Fe ii 4122.6 A. Hence, the [K v] diagnostic may not be used for astrophysical sources that show a strong Fe ii emission line spectrum.

  18. Monitoring the Orion Nebula Cluster

    Science.gov (United States)

    Reipurth, Bo

    The VYSOS (Variable Young Stars Optical Survey) project has at its disposal five small telescopes: a 5-inch and a 20-inch robotic optical imaging telescope in Hawaii funded by the NSF, and a 6-inch robotic optical imaging telescope, a 32-inch robotic infrared imaging telescope, and a 60-inch optical spectroscopic telescope in Chile, funded and operated from Germany. Through an agreement between the leaders of the two sites (B. Reipurth and R. Chini), it has been decided to devote a significant fraction of time on these facilities to a large Key Project, conducting a massive monitoring survey of the Orion Nebula Cluster. The vast data streams are being reduced through automated customized pipelines. The applicant seeks funding to employ a postdoc and an undergraduate assistant to work at the University of Hawaii and collaborate on the analysis of the data. Virtually all young stars are variable, with a wide range of amplitudes and characteristic timescales. This is mainly due to accretion shocks as material from circumstellar disks fall onto the stars along magnetic funnel flows, but also giant star spots, magnetic flares, occultations by orbiting dust condensations, and eclipses by companions can modulate the light from the nascent star. It is increasingly recognized that the rather static view of pre-main sequence evolution that has prevailed for many years is misleading, and that time-dependent phenomena may hold the key to an understanding of the way young stars grow and their circumstellar environments evolve. The VYSOS project is designed to bring sophisticated modern techniques to bear on the long neglected problem of variability in young solar type stars. To interpret the observations they will be compared to sophisticated MHD models of circumstellar disks around young stars. The Orion Nebula Cluster is the nearest rich region of star formation, and numerous, albeit heterogeneous, studies exist of the cluster members. The present study will provide the first

  19. Monitoring the Crab Nebula with LOFT

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2012-01-01

    From 2008-2010, the Crab Nebula was found to decline by 7% in the 15-50 keV band, consistently in Fermi GBM, INTEGRAL IBIS, SPI, and JEMX, RXTE PCA, and Swift BAT. From 2001-2010, the 15-50 keV flux from the Crab Nebula typically varied by about 3.5% per year. Analysis of RXTE PCA data suggests possible spectral variations correlated with the flux variations. I will present estimates of the LOFT sensitivity to these variations. Prior to 2001 and since 2010, the observed flux variations have been much smaller. Monitoring the Crab with the LOFT WFM and LAD will provide precise measurements of flux variations in the Crab Nebula if it undergoes a similarly active episode.

  20. a Surprise from the Pulsar in the Crab Nebula

    Science.gov (United States)

    1995-11-01

    New observations of the spectrum of the rapidly spinning neutron star (the `pulsar') in the Crab Nebula have been carried out with the ESO 3.5-metre New Technology Telescope (NTT) by a group of Italian astronomers [1]. Because of greatly improved spectral resolution which allows to register even very fine details in the pulsar's spectrum, they are able to determine for the first time with high accuracy the overall dependance of the emission on wavelength, i.e. the `shape' of the spectrum. Quite unexpectedly, they also detect a hitherto unknown 100 A (10 nm) broad `absorption dip', which can be securely attributed to the pulsar. These results open an exciting new window for the study of the extreme physical processes close to a pulsar. The Nature of Pulsars It is estimated that there may be as many as 100 million neutron stars in our Galaxy. A neutron star is the superdense remnant of the extremely violent supernova explosion that occurs at the end of the life of a comparatively massive star. In fact, all stars that are more than about 6 times heavier than the Sun are believed to end their lives as supernovae. During the explosion, the central core of the dying star collapses in a few milliseconds and the matter at the centre is compressed to a density comparable to that of an atomic nucleus. Due to the enormous inward pressure, the atomic particles are squeezed together into a kind of neutron jam. The outcome is the formation of a neutron star with a diameter of 10-15 kilometres, weighing as much as the Sun. In accordance with the physical law that implies that the rotation momentum of the exploding star must be conserved, newborn neutron stars will rotate very rapidly around their axis, in some cases as fast as 100 times per second. In the same way, the new neutron star is expected to possess a strong magnetic field. Of these myriads of neutron stars, about 700 have been observed to emit radio pulses (hence the name `pulsar'). A few of these can also be detected

  1. The Orion Nebula: The Jewel in the Sword

    Science.gov (United States)

    2001-01-01

    -Res - JPEG: 2273 x 2784 pix - 976k] Caption : PR Photo 03d/01 shows a small section of the observational data (in one infrared spectral band only, here reproduced in B/W) on which PR Photo 03a/01 is based. The field is centred on one of the famous Orion silhouette disks (Orion 114-426) (it is located approximately halfway between the centre and the right edge of PR Photo 03c/01 ). The dusty disk itself is seen edge-on as a dark streak against the background emission of the Orion Nebula, while the bright fuzzy patches on either side betray the presence of the embedded parent star that illuminates tenuous collections of dust above its north and south poles to create these small reflection nebulae. Recent HST studies suggest that the very young Orion 114-426 disk - that is thirty times bigger than our present-day Solar System - may already be showing signs of forming its own proto-planetary system. Technical information about this photo is available below. It is even possible to see disks of dust and gas surrounding a few of the young stars, as silhouettes in projection against the bright background of the nebula. Many of these disks are very small and usually only seen on images obtained with the Hubble Space Telescope (HST) [2]. However, under the best seeing conditions on Paranal, the sharpness of VLT images at infrared wavelengths approaches that of the HST in this spectral band, revealing some of these disks, as shown in PR Photo 03d/01 . Indeed, the theoretical image sharpness of the 8.2-m VLT is more than three times better than that of the 2.4-m HST. Thus, the VLT will soon yield images of small regions with even higher resolution by means of the High-Resolution Near-Infrared Camera (CONICA) and the Nasmyth Adaptive Optics System (NAOS) that will compensate the smearing effect introduced by the turbulence in the atmosphere. Later on, extremely sharp images will be obtained when all four VLT telescopes are combined to form the Very Large Telescope Interferometer (VLTI

  2. THE SHAPING EFFECT OF COLLIMATED FAST OUTFLOWS IN THE EGG NEBULA

    International Nuclear Information System (INIS)

    Dinh-V-Trung; Lim, Jeremy

    2009-01-01

    We present high angular resolution observations of the HC 3 N J = 5-4 line from the Egg nebula, which is the archetype of proto-planetary nebulae (PPNs). We find that the HC 3 N emission in the approaching and receding portion of the envelope traces a clumpy hollow shell, similar to that seen in normal carbon-rich envelopes. Near the systemic velocity, the hollow shell is fragmented into several large blobs or arcs with missing portions correspond spatially to locations of previously reported high-velocity outflows in the Egg nebula. This provides direct evidence for the disruption of the slowly expanding envelope ejected during the AGB phase by the collimated fast outflows initiated during the transition to the PPN phase. From modeling the HC 3 N distribution, we could reproduce qualitatively the spatial kinematics of the HC 3 N J = 5-4 emission using a HC 3 N shell with two pairs of cavities cleared by the collimated high-velocity outflows along the polar direction and in the equatorial plane. We infer a relatively high abundance of HC 3 N/H 2 ∼ 3 x 10 -6 for an estimated mass-loss rate of 3 x 10 -5 M sun yr -1 in the HC 3 N shell. The high abundance of HC 3 N and the presence of some weaker J = 5-4 emission in the vicinity of the central post-AGB star suggest an unusually efficient formation of this molecule in the Egg nebula.

  3. Models of the formation of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Cassen, P.; Summers, A.

    1983-01-01

    Protostellar cloud collapse and solar nebula formation models indicate that the size of the nebula produced will be larger in terms of both gas centrifugal balance R(CF) and collapse time diffusion length R(V). From this, it can be deduced that low mass nebulas are produced if (R(V)/R(CF))-squared is much greater than unity, while nebulas result for values lower than approximately unity. The total angular momentum value distinguishes most current models of the solar nebula. Analytic expressions for the surface density, nebular mass flux and photospheric temperature distributions during the formation stage are presented for simple modes illustrating and general properties of growing protostellar disks.

  4. Large proper motions in the Orion nebula

    International Nuclear Information System (INIS)

    Cudworth, K.M.; Stone, R.C.

    1977-01-01

    Several nebular features, as well as one faint star, with large proper motions were identified within the Orion nebula. The measured proper motions correspond to tangential velocities of up to approximately 70 km sec -1 . One new probable variable star was also found

  5. Turbulent Magnetic Relaxation in Pulsar Wind Nebulae

    Science.gov (United States)

    Zrake, Jonathan; Arons, Jonathan

    2017-09-01

    We present a model for magnetic energy dissipation in a pulsar wind nebula. A better understanding of this process is required to assess the likelihood that certain astrophysical transients may be powered by the spin-down of a “millisecond magnetar.” Examples include superluminous supernovae, gamma-ray bursts, and anticipated electromagnetic counterparts to gravitational wave detections of binary neutron star coalescence. Our model leverages recent progress in the theory of turbulent magnetic relaxation to specify a dissipative closure of the stationary magnetohydrodynamic (MHD) wind equations, yielding predictions of the magnetic energy dissipation rate throughout the nebula. Synchrotron losses are self-consistently treated. To demonstrate the model’s efficacy, we show that it can reproduce many features of the Crab Nebula, including its expansion speed, radiative efficiency, peak photon energy, and mean magnetic field strength. Unlike ideal MHD models of the Crab (which lead to the so-called σ-problem), our model accounts for the transition from ultra to weakly magnetized plasma flow and for the associated heating of relativistic electrons. We discuss how the predicted heating rates may be utilized to improve upon models of particle transport and acceleration in pulsar wind nebulae. We also discuss implications for the Crab Nebula’s γ-ray flares, and point out potential modifications to models of astrophysical transients invoking the spin-down of a millisecond magnetar.

  6. Escape from planetary neighbourhoods

    NARCIS (Netherlands)

    Waalkens, H.; Burbanks, A.; Wiggins, S.

    2005-01-01

    In this paper we use recently developed phase-space transport theory coupled with a so-called classical spectral theorem to develop a dynamically exact and computationally efficient procedure for studying escape from a planetary neighbourhood. The ‘planetary neighbourhood’ is a bounded region of

  7. Planetary Atmospheric Electricity

    CERN Document Server

    Leblanc, F; Yair, Y; Harrison, R. G; Lebreton, J. P; Blanc, M

    2008-01-01

    This volume presents our contemporary understanding of atmospheric electricity at Earth and in other solar system atmospheres. It is written by experts in terrestrial atmospheric electricity and planetary scientists. Many of the key issues related to planetary atmospheric electricity are discussed. The physics presented in this book includes ionisation processes in planetary atmospheres, charge generation and separation, and a discussion of electromagnetic signatures of atmospheric discharges. The measurement of thunderstorms and lightning, including its effects and hazards, is highlighted by articles on ground and space based instrumentation, and new missions.Theory and modelling of planetary atmospheric electricity complete this review of the research that is undertaken in this exciting field of space science. This book is an essential research tool for space scientists and geoscientists interested in electrical effects in atmospheres and planetary systems. Graduate students and researchers who are new to t...

  8. DISCOVERY OF A HALO AROUND THE HELIX NEBULA NGC 7293 IN THE WISE ALL-SKY SURVEY

    International Nuclear Information System (INIS)

    Zhang Yong; Hsia, Chih-Hao; Kwok, Sun

    2012-01-01

    We report the discovery of an extended halo (∼40' in diameter) around the planetary nebula NGC 7293 (the Helix Nebula) observed in the 12 μm band from the Wide-field Infrared Survey Explorer all-sky survey. The mid-infrared halo has an axisymmetric structure with a sharp boundary to the northeast and a more diffuse boundary to the southwest, suggesting an interaction between the stellar wind and the interstellar medium (ISM). The symmetry axis of the halo is well aligned with that of a northeast arc, suggesting that the two structures are physically associated. We have attempted to fit the observed geometry with a model of a moving steady-state stellar wind interacting with the ISM. Possible combinations of the ISM density and the stellar velocity are derived from these fittings. The discrepancies between the model and the observations suggest that the stellar mass loss has a more complicated history, including possible time and angle dependences.

  9. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.

    Science.gov (United States)

    Keenan, F P; Aller, L H; Ryans, R S; Hyung, S

    2001-08-14

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027.

  10. Planetary Accretion, Oxygen Isotopes and the Central Limit Theorem

    Science.gov (United States)

    Nuth, Joseph A., III; Hill, Hugh G. M.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    The accumulation of presolar dust into increasingly larger aggregates (CAIs and Chondrules, Asteroids, Planets) should result in a very drastic reduction in the numerical spread in oxygen isotopic composition between bodies of similar size, in accord with the Central Limit Theorem. Observed variations in oxygen isotopic composition are many orders of magnitude larger than would be predicted by a simple, random accumulation model that begins in a well-mixed nebula - no matter which size-scale objects are used as the beginning or end points of the calculation. This discrepancy implies either that some as yet unspecified process acted on the solids in the Solar Nebula to increase the spread in oxygen isotopic composition during each and every stage of accumulation or that the nebula was heterogeneous and maintained this heterogeneity throughout most of nebular history. Large-scale nebular heterogeneity would have significant consequences for many areas of cosmochemistry, including the application of some well-known isotopic systems to the dating of nebular events or the prediction of bulk compositions of planetary bodies on the basis of a uniform cosmic abundance.

  11. 'Peony Nebula' Star Settles for Silver Medal

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Poster Version Movie If our galaxy, the Milky Way, were to host its own version of the Olympics, the title for the brightest known star would go to a massive star called Eta Carina. However, a new runner-up now the second-brightest star in our galaxy has been discovered in the galaxy's dusty and frenzied interior. This image from NASA's Spitzer Space Telescope shows the new silver medalist, circled in the inset above, in the central region of our Milky Way. Dubbed the 'Peony nebula' star, this blazing ball of gas shines with the equivalent light of 3.2 million suns. The reigning champ, Eta Carina, produces the equivalent of 4.7 million suns worth of light though astronomers say these estimates are uncertain, and it's possible that the Peony nebula star could be even brighter than Eta Carina. If the Peony star is so bright, why doesn't it stand out more in this view? The answer is dust. This star is located in a very dusty region jam packed with stars. In fact, there could be other super bright stars still hidden deep in the stellar crowd. Spitzer's infrared eyes allowed it to pierce the dust and assess the Peony nebula star's true brightness. Likewise, infrared data from the European Southern Observatory's New Technology Telescope in Chile were integral in calculating the Peony nebula star's luminosity. The Peony nebula, which surrounds the Peony nebular star, is the reddish cloud of dust in and around the white circle. The movie begins by showing a stretch of the dusty and frenzied central region of our Milky Way galaxy. It then zooms in to reveal the 'Peony nebula' star the new second-brightest star in the Milky Way, discovered in part by NASA's Spitzer Space Telescope. This is a three-color composite showing infrared observations from two Spitzer instruments. Blue represents 3.6-micron light and green shows light of 8 microns, both captured by Spitzer's infrared array

  12. Magnesium isotope evidence that accretional vapour loss shapes planetary compositions

    Science.gov (United States)

    Hin, Remco C.; Coath, Christopher D.; Carter, Philip J.; Nimmo, Francis; Lai, Yi-Jen; Pogge von Strandmann, Philip A. E.; Willbold, Matthias; Leinhardt, Zoë M.; Walter, Michael J.; Elliott, Tim

    2017-09-01

    It has long been recognized that Earth and other differentiated planetary bodies are chemically fractionated compared to primitive, chondritic meteorites and, by inference, the primordial disk from which they formed. However, it is not known whether the notable volatile depletions of planetary bodies are a consequence of accretion or inherited from prior nebular fractionation. The isotopic compositions of the main constituents of planetary bodies can contribute to this debate. Here we develop an analytical approach that corrects a major cause of measurement inaccuracy inherent in conventional methods, and show that all differentiated bodies have isotopically heavier magnesium compositions than chondritic meteorites. We argue that possible magnesium isotope fractionation during condensation of the solar nebula, core formation and silicate differentiation cannot explain these observations. However, isotopic fractionation between liquid and vapour, followed by vapour escape during accretionary growth of planetesimals, generates appropriate residual compositions. Our modelling implies that the isotopic compositions of magnesium, silicon and iron, and the relative abundances of the major elements of Earth and other planetary bodies, are a natural consequence of substantial (about 40 per cent by mass) vapour loss from growing planetesimals by this mechanism.

  13. Magnesium isotope evidence that accretional vapour loss shapes planetary compositions.

    Science.gov (United States)

    Hin, Remco C; Coath, Christopher D; Carter, Philip J; Nimmo, Francis; Lai, Yi-Jen; Pogge von Strandmann, Philip A E; Willbold, Matthias; Leinhardt, Zoë M; Walter, Michael J; Elliott, Tim

    2017-09-27

    It has long been recognized that Earth and other differentiated planetary bodies are chemically fractionated compared to primitive, chondritic meteorites and, by inference, the primordial disk from which they formed. However, it is not known whether the notable volatile depletions of planetary bodies are a consequence of accretion or inherited from prior nebular fractionation. The isotopic compositions of the main constituents of planetary bodies can contribute to this debate. Here we develop an analytical approach that corrects a major cause of measurement inaccuracy inherent in conventional methods, and show that all differentiated bodies have isotopically heavier magnesium compositions than chondritic meteorites. We argue that possible magnesium isotope fractionation during condensation of the solar nebula, core formation and silicate differentiation cannot explain these observations. However, isotopic fractionation between liquid and vapour, followed by vapour escape during accretionary growth of planetesimals, generates appropriate residual compositions. Our modelling implies that the isotopic compositions of magnesium, silicon and iron, and the relative abundances of the major elements of Earth and other planetary bodies, are a natural consequence of substantial (about 40 per cent by mass) vapour loss from growing planetesimals by this mechanism.

  14. Formation of iron sulphide in solar nebula

    Science.gov (United States)

    Kerridge, J. F.

    1976-01-01

    Noting that the iron sulfide in the Orgueil carbonaceous meteorite is an Fe-deficient monosulfide (pyrrhotite), it is suggested that such mineral chemistry is inconsistent with equilibrium condensation of the solar nebula and that the course of condensation may have been modified by kinetic effects. The effect of Ni on the reaction between Fe and S to produce FeS is examined, and possible reasons are considered for the fact that the cited meteorite differs in both crystal structure and Ni content from the predictions of equilibrium condensation. It is proposed that sulfide formation in the solar nebula may have been inhibited by sluggish diffusion, so that sulfur began to react with previously condensed troilite to form pyrrhotite. On this basis, observations of the Orgueil sulfides are shown to suggest that the course of solar-system condensation was modified by kinetic effects below about 700 K and that equilibrium may not have been achieved.

  15. Gazetteer of Planetary Nomenclature

    Data.gov (United States)

    National Aeronautics and Space Administration — Planetary nomenclature, like terrestrial nomenclature, is used to uniquely identify a feature on the surface of a planet or satellite so that the feature can be...

  16. Multiband observations of the Crab Nebula

    International Nuclear Information System (INIS)

    Krassilchtchikov, A M; Bykov, A M; Castelletti, G M; Dubner, G M; Kargaltsev, O Yu; Pavlov, G G

    2017-01-01

    Results of simultaneous imaging of the Crab Nebula in the radio (JVLA), optical ( HST ), and X-ray ( Chandra ) bands are presented. The images show a variety of small-scale structures, including wisps mainly located to the north-west of the pulsar and knots forming a ring-like structure associated with the termination shock of the pulsar wind. The locations of the structures in different bands do not coincide with each other. (paper)

  17. Nebula observations. Catalogues and archive of photoplates

    Science.gov (United States)

    Shlyapnikov, A. A.; Smirnova, M. A.; Elizarova, N. V.

    2017-12-01

    A process of data systematization based on "Academician G.A. Shajn's Plan" for studying the Galaxy structure related to nebula observations is considered. The creation of digital versions of catalogues of observations and publications is described, as well as their presentation in HTML, VOTable and AJS formats and basic principles of work in the interactive application of International Virtual Observatory the Aladin Sky Atlas.

  18. Nebulae at keratoconus--the result after excimer laser removal.

    Science.gov (United States)

    Fagerholm, P; Fitzsimmons, T; Ohman, L; Orndahl, M

    1993-12-01

    Ten patients underwent excimer laser ablation due to nebula formation at keratoconus. The nebulae interfered significantly with contact lens fit or wearing time. The mean follow-up time in these patients was 16.5 months. Following surgery all patients could be successfully fitted with a contact lens and thereby obtain good visual acuity. Furthermore, contact lens wearing time was 8 hours or more in all cases. In 2 patients the nebulae recurred but were successfully retreated.

  19. Environmental impact study of Orion Nebula dust

    International Nuclear Information System (INIS)

    Cardelli, J.A.; Clayton, G.C.

    1988-01-01

    In this paper, new high-quality extinction curves are presented for Theta-1 Ori A, C, and D, and Theta-2 Ori A and B, over the wavelength range 3300-6000 A. These are coupled with near-infrared and ultraviolet data to produce extinction curves from 0.12 to 3.5 microns. The Orion Nebula region is interesting in that most of the known processes of dust-grain growth, processing, and destruction may be operating nearly simultaneously in close proximity to one another. Each of these processes is considered with respect to the observed extinction curves and environmental conditions in the Orion Nebula and its associated molecular cloud. Plausible grain populations are fit to the observed extinction curves. A good fit to the average Theta Ori extinction curve can be obtained with: (1) a combination of larger than normal silicate grains produced through coagulation and accretion; (2) evaporation of volatile mantles; and (3) a reduction in the column density of small (smaller than 0.01 micron) grains responsible for the bump and far-ultraviolet extinction through differential acceleration due to radiation pressure and possible evaporation. It seems plausible to explain the observed peculiar extinction in the Orion Nebula simply by environmental effects on otherwise normal grains. 59 references

  20. A PHOTOMETRICALLY AND MORPHOLOGICALLY VARIABLE INFRARED NEBULA IN L483

    International Nuclear Information System (INIS)

    Connelley, Michael S.; Hodapp, Klaus W.; Fuller, Gary A.

    2009-01-01

    We present narrow and broad K-band observations of the Class 0/I source IRAS 18148-0440 that span 17 years. The infrared nebula associated with this protostar in the L483 dark cloud is both morphologically and photometrically variable on a timescale of only a few months. This nebula appears to be an infrared analog to other well known optically visible variable nebulae associated with young stars, such as Hubble's Variable Nebula. Along with Cepheus A, this is one of the first large variable nebulae to be found that is only visible in the infrared. The variability of this nebula is most likely due to changing illumination of the cloud rather than any motion of the structure in the nebula. Both morphological and photometric changes are observed on a timescale only a few times longer than the light crossing time of the nebula, suggesting very rapid intrinsic changes in the illumination of the nebula. Our narrowband observations also found that H 2 knots are found nearly twice as far to the east of the source as to its west, and that H 2 emission extends farther east of the source than the previously known CO outflow.

  1. Radiation emitting devices act

    International Nuclear Information System (INIS)

    1970-01-01

    This Act, entitled the Radiation Emitting Devices Act, is concerned with the sale and importation of radiation emitting devices. Laws relating to the sale, lease or import, labelling, advertising, packaging, safety standards and inspection of these devices are listed as well as penalties for any person who is convicted of breaking these laws

  2. Interstellar and Solar Nebula Materials in Cometary Dust

    Science.gov (United States)

    Messenger, Scott; Nakamura-Messenger, Keiko; Keller, Lindsay; Nguyen, Ann; Clemett, Simon

    2017-01-01

    Laboratory studies of cometary dust collected in the stratosphere and returned from comet 81P/Wild 2 by the Stardust spacecraft have revealed ancient interstellar grains and molecular cloud organic matter that record a range of astrophysical processes and the first steps of planetary formation. Presolar materials are rarer meteorites owing to high temperature processing in the solar nebula and hydrothermal alteration on their asteroidal parent bodies. The greater preservation of presolar materials in comets is attributed to their low accretion temperatures and limited planetary processing. Yet, comets also contain a large complement of high temperature materials from the inner Solar System. Owing to the limited and biased sampling of comets to date, the proportions of interstellar and Solar System materials within them remains highly uncertain. Interstellar materials are identified by coordinated isotopic, mineralogical, and chemical measurements at the scale of individual grains. Chondritic porous interplanetary dust particles (CP IDPs) that likely derive from comets are made up of 0.1 - 10 micron-sized silicates, Fe-Ni-sulfides, oxides, and other phases bound by organic material. As much as 1% of the silicates are interstellar grains that have exotic isotopic compositions imparted by nucleosynthetic processes in their parent stars. Crystalline silicates in CP IDPs dominantly have normal isotopic compositions and probably formed in the Solar System. 81P samples include isotopically normal refractory minerals that resemble Ca-Al rich inclusions and chondrules common in meteorites. The origins of sub-micron amorphous silicates in IDPs are not certain, but at least a few % of them are interstellar grains. The remainder have isotopic compositions consistent with Solar System origins and elemental compositions that are inconsistent with interstellar grain properties, thus favoring formation in the solar nebula [4]. The organic component in comets and primitive

  3. A PROTOSOLAR NEBULA ORIGIN FOR THE ICES AGGLOMERATED BY COMET 67P/CHURYUMOV–GERASIMENKO

    Energy Technology Data Exchange (ETDEWEB)

    Mousis, O.; Vernazza, P. [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Lunine, J. I. [Center For Radiophysics And Space Research, Space Sciences Building Cornell University, Ithaca, NY 14853 (United States); Luspay-Kuti, A.; Hässig, M.; Waite, J. H. [Department of Space Research, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228 (United States); Guillot, T. [Laboratoire J.-L. Lagrange, Université de Nice-Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, BP 4229, F-06304 Nice (France); Marty, B. [CRPG-CNRS, Nancy-Université, 15 rue Notre Dame des Pauvres, F-54501 Vandoeuvre-lès-Nancy (France); Ali-Dib, M. [Université de Franche-Comté, Institut UTINAM, CNRS/INSU, UMR 6213, Besançon Cedex (France); Wurz, P.; Altwegg, K.; Bieler, A.; Rubin, M., E-mail: olivier.mousis@lam.fr [Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

    2016-03-10

    The nature of the icy material accreted by comets during their formation in the outer regions of the protosolar nebula (PSN) is a major open question in planetary science. Some scenarios of comet formation predict that these bodies agglomerated from crystalline ices condensed in the PSN. Concurrently, alternative scenarios suggest that comets accreted amorphous ice originating from the interstellar cloud or from the very distant regions of the PSN. On the basis of existing laboratory and modeling data, we find that the N{sub 2}/CO and Ar/CO ratios measured in the coma of the Jupiter-family comet 67P/Churyumov–Gerasimenko by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument on board the European Space Agency’s Rosetta spacecraft match those predicted for gases trapped in clathrates. If these measurements are representative of the bulk N{sub 2}/CO and Ar/CO ratios in 67P/Churyumov–Gerasimenko, it implies that the ices accreted by the comet formed in the nebula and do not originate from the interstellar medium, supporting the idea that the building blocks of outer solar system bodies have been formed from clathrates and possibly from pure crystalline ices. Moreover, because 67P/Churyumov–Gerasimenko is impoverished in Ar and N{sub 2}, the volatile enrichments observed in Jupiter’s atmosphere cannot be explained solely via the accretion of building blocks with similar compositions and require an additional delivery source. A potential source may be the accretion of gas from the nebula that has been progressively enriched in heavy elements due to photoevaporation.

  4. A virtual observatory for photoionized nebulae: the Mexican Million Models database (3MdB).

    Science.gov (United States)

    Morisset, C.; Delgado-Inglada, G.; Flores-Fajardo, N.

    2015-04-01

    Photoionization models obtained with numerical codes are widely used to study the physics of the interstellar medium (planetary nebulae, HII regions, etc). Grids of models are performed to understand the effects of the different parameters used to describe the regions on the observables (mainly emission line intensities). Most of the time, only a small part of the computed results of such grids are published, and they are sometimes hard to obtain in a user-friendly format. We present here the Mexican Million Models dataBase (3MdB), an effort to resolve both of these issues in the form of a database of photoionization models, easily accessible through the MySQL protocol, and containing a lot of useful outputs from the models, such as the intensities of 178 emission lines, the ionic fractions of all the ions, etc. Some examples of the use of the 3MdB are also presented.

  5. Forming H-shaped and barrel-shaped nebulae with interacting jets

    Science.gov (United States)

    Akashi, Muhammad; Bear, Ealeal; Soker, Noam

    2018-04-01

    We conduct three-dimensional hydrodynamical simulations of two opposite jets with large opening angles launched from a binary stellar system into a previously ejected shell and show that the interaction can form barrel-like and H-like shapes in the descendant nebula. Such features are observed in planetary nebulae (PNe) and supernova remnants. Under our assumption, the dense shell is formed by a short instability phase of the giant star as it interacts with a stellar companion, and the jets are then launched by the companion as it accretes mass through an accretion disc from the giant star. We find that the H-shaped and barrel-shaped morphological features that the jets form evolve with time, and that there are complicated flow patterns, such as vortices, instabilities, and caps moving ahead along the symmetry axis. We compare our numerical results with images of 12 PNe, and show that jet-shell interaction that we simulate can account for the barrel-like or H-like morphologies that are observed in these PNe.

  6. Starlight excitation of permitted lines in the Orion Nebula

    International Nuclear Information System (INIS)

    Grandi, S.A.

    1975-01-01

    From an idealized model of the Orion Nebula and from an analysis of line ratios it is shown that direct starlight excitation of the permitted O I line dominates over recombination and Lyman line fluorescence. The line strengths predicted by this mechanism agree reasonably well with those observed in the Orion Nebula. The application of direct starlight excitation to other ions is also discussed

  7. An Analysis of Spectra in the Red Rectangle Nebula

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... This paper presents an analysis of a series of spectra in the Red Rectangle nebula. Only the reddest part of the spectra can safely be attributed to light from the nebula, and indicates Rayleigh scattering by the gas, in conformity with the large angles of scattering involved and the proximity of the star. In the ...

  8. Airships for Planetary Exploration

    Science.gov (United States)

    Colozza, Anthony

    2004-01-01

    The feasibility of utilizing an airship for planetary atmospheric exploration was assessed. The environmental conditions of the planets and moons within our solar system were evaluated to determine their applicability for airship flight. A station-keeping mission of 50 days in length was used as the baseline mission. Airship sizing was performed utilizing both solar power and isotope power to meet the baseline mission goal at the selected planetary location. The results show that an isotope-powered airship is feasible within the lower atmosphere of Venus and Saturn s moon Titan.

  9. A large bubble around the Crab Nebula

    Science.gov (United States)

    Romani, Roger W.; Reach, William T.; Koo, Bon Chul; Heiles, Carl

    1990-01-01

    IRAS and 21 cm observations of the interstellar medium around the Crab nebula show evidence of a large bubble surrounded by a partial shell. If located at the canonical 2 kpc distance of the Crab pulsar, the shell is estimated to have a radius of about 90 pc and to contain about 50,000 solar masses of swept-up gas. The way in which interior conditions of this bubble can have important implications for observations of the Crab are described, and the fashion in which presupernova evolution of the pulsar progenitor has affected its local environment is described.

  10. ELEMENT MASSES IN THE CRAB NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Sibley, Adam R.; Katz, Andrea M.; Satterfield, Timothy J.; Vanderveer, Steven J.; MacAlpine, Gordon M. [Department of Physics and Astronomy, Trinity University, San Antonio, TX 78212 (United States)

    2016-10-01

    Using our previously published element abundance or mass-fraction distributions in the Crab Nebula, we derived actual mass distributions and estimates for overall nebular masses of hydrogen, helium, carbon, nitrogen, oxygen and sulfur. As with the previous work, computations were carried out for photoionization models involving constant hydrogen density and also constant nuclear density. In addition, employing new flux measurements for [Ni ii]  λ 7378, along with combined photoionization models and analytic computations, a nickel abundance distribution was mapped and a nebular stable nickel mass estimate was derived.

  11. The Search for Binaries in Post-Asymptotic Giant Branch Stars: Do Binary Companions Shape the Nebulae?

    Directory of Open Access Journals (Sweden)

    Bruce J. Hrivnak

    2012-03-01

    Full Text Available Binary companions are often invoked to explain the axial and point symmetry seen in the majority of planetary nebulae and proto-planetary nebulae (PPNs. To explore this hypothesis, we have undertaken a long-term (20 year study of light and velocity variations in PPNs. From the photometric study of 24 PPNs, we find that all vary in brightness, and from a subset of 12 carbon-rich PPNs of F-G spectral type we find periods of 35-155 days, with the cooler having the longer periods. The variations are seen to be due to pulsation; no photometric evidence for binarity is seen. A radial velocity study of a sub-sample of seven of the brightest of these shows that they all vary with the pulsation periods. Only one shows evidence of a longer-term variation that we tentatively identify as being due to a binary companion. We conclude that the present evidence for the binary nature of these PPNs is meager and that any undetected companions of these PPNs must be of low mass ( 30 years.

  12. Evidence for Reduced, Carbon-rich Regions in the Solar Nebula from an Unusual Cometary Dust Particle

    Energy Technology Data Exchange (ETDEWEB)

    De Gregorio, Bradley T.; Stroud, Rhonda M. [Materials Science and Technology Division, Naval Research Laboratory, Code 6366, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Nittler, Larry R. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Kilcoyne, A. L. David, E-mail: bradley.degregorio@nrl.navy.mil [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mailstop 7R0222, Berkeley, CA 94720 (United States)

    2017-10-20

    Geochemical indicators in meteorites imply that most formed under relatively oxidizing conditions. However, some planetary materials, such as the enstatite chondrites, aubrite achondrites, and Mercury, were produced in reduced nebular environments. Because of large-scale radial nebular mixing, comets and other Kuiper Belt objects likely contain some primitive material related to these reduced planetary bodies. Here, we describe an unusual assemblage in a dust particle from comet 81P/Wild 2 captured in silica aerogel by the NASA Stardust spacecraft. The bulk of this ∼20 μ m particle is comprised of an aggregate of nanoparticulate Cr-rich magnetite, containing opaque sub-domains composed of poorly graphitized carbon (PGC). The PGC forms conformal shells around tiny 5–15 nm core grains of Fe carbide. The C, N, and O isotopic compositions of these components are identical within errors to terrestrial standards, indicating a formation inside the solar system. Magnetite compositions are consistent with oxidation of reduced metal, similar to that seen in enstatite chondrites. Similarly, the core–shell structure of the carbide + PGC inclusions suggests a formation via FTT reactions on the surface of metal or carbide grains in warm, reduced regions of the solar nebula. Together, the nanoscale assemblage in the cometary particle is most consistent with the alteration of primary solids condensed from a C-rich, reduced nebular gas. The nanoparticulate components in the cometary particle provide the first direct evidence from comets of reduced, carbon-rich regions that were present in the solar nebula.

  13. On Aryabhata's Planetary Constants

    OpenAIRE

    Kak, Subhash

    2001-01-01

    This paper examines the theory of a Babylonian origin of Aryabhata's planetary constants. It shows that Aryabhata's basic constant is closer to the Indian counterpart than to the Babylonian one. Sketching connections between Aryabhata's framework and earlier Indic astronomical ideas on yugas and cyclic calendar systems, it is argued that Aryabhata's system is an outgrowth of an earlier Indic tradition.

  14. The planetary scientist's companion

    CERN Document Server

    Lodders, Katharina

    1998-01-01

    A comprehensive and practical book of facts and data about the Sun, planets, asteroids, comets, meteorites, the Kuiper belt and Centaur objects in our solar system. Also covered are properties of nearby stars, the interstellar medium, and extra-solar planetary systems.

  15. Si isotope homogeneity of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  16. The Eagle Nebula Science on NIF experiment

    Science.gov (United States)

    Kane, Jave; Heeter, Robert; Martinez, David; Pound, Marc; Remington, Bruce; Ryutov, Dmitri; Smalyuk, Vladimir

    2012-10-01

    The Eagle Nebula NIF experiment was one of nine selected for laser time through the Science on NIF program. The goal of this scale laboratory experiment is to study the dynamic evolution of distinctive structures in star forming regions of astrophysical molecular clouds such as the Pillars of the Eagle Nebula. That evolution is driven by photoionizing radiation from nearby stars. A critical aspect of the radiation is its very directional nature at the photoionization front. The long duration of the drive and its directionality can generate new classes of instabilities and dynamic flows at the front that may be responsible for the shapes of Pillars and other structures. The experiment will leverage and modify the existing NIF Radiation Transport platform, replacing the target at the back end of the halfraum with a collimating aperture, and extending the existing 20 ns drive to longer times, using a combination of gas fill and other new design features. The apertured, quasi-collimated drive will be used to drive a target placed 2 mm away from the aperture. The astrophysical background and the status of the experimental design will be presented.

  17. BD-22deg3467, a DAO-type Star Exciting the Nebula Abell 35

    Science.gov (United States)

    Ziegler, M.; Rauch, T.; Werner, K.; Koppen, J.; Kruk, J. W.

    2013-01-01

    to the white dwarf state. This would explain why it is not surrounded by a planetary nebula. However, the star, ionizes the ambient interstellar matter, mimicking a planetary nebula.

  18. BD-22°3467, a DAO-type star exciting the nebula Abell 35

    Science.gov (United States)

    Ziegler, M.; Rauch, T.; Werner, K.; Köppen, J.; Kruk, J. W.

    2012-12-01

    state. This would explain why it is not surrounded by a planetary nebula. However, the star, ionizes the ambient interstellar matter, mimicking a planetary nebula. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Tables 1 and 2, and Fig. 2 are available in electronic form at http://www.aanda.org

  19. Illuminating gas inflows/outflows in the MUSE deepest fields: Lyα nebulae around forming galaxies at z ≃ 3.3

    Science.gov (United States)

    Vanzella, E.; Balestra, I.; Gronke, M.; Karman, W.; Caminha, G. B.; Dijkstra, M.; Rosati, P.; De Barros, S.; Caputi, K.; Grillo, C.; Tozzi, P.; Meneghetti, M.; Mercurio, A.; Gilli, R.

    2017-03-01

    We report the identification of extended Lyα nebulae at z ≃ 3.3 in the Hubble Ultra Deep Field (HUDF, ≃40 kpc × 80 kpc) and behind the Hubble Frontier Field galaxy cluster MACSJ0416 (≃40 kpc), spatially associated with groups of star-forming galaxies. VLT/MUSE integral field spectroscopy reveals a complex structure with a spatially varying double-peaked Lyα emission. Overall, the spectral profiles of the two Lyα nebulae are remarkably similar, both showing a prominent blue emission, more intense and slightly broader than the red peak. From the first nebula, located in the HUDF, no X-ray emission has been detected, disfavouring the possible presence of active galactic nuclei. Spectroscopic redshifts have been derived for 11 galaxies within 2 arcsec from the nebula and spanning the redshift range 1.037 < z < 5.97. The second nebula, behind MACSJ0416, shows three aligned star-forming galaxies plausibly associated with the emitting gas. In both systems, the associated galaxies reveal possible intense rest-frame-optical nebular emissions lines [O III] λλ4959, 5007+Hβ with equivalent widths as high as 1500 Å rest frame and star formation rates ranging from a few to tens of solar masses per year. A possible scenario is that of a group of young, star-forming galaxies emitting ionizing radiation that induces Lyα fluorescence, therefore revealing the kinematics of the surrounding gas. Also Lyα powered by star formation and/or cooling radiation may resemble the double-peaked spectral properties and the morphology observed here. If the intense blue emission is associated with inflowing gas, then we may be witnessing an early phase of galaxy or a proto-cluster (or group) formation.

  20. Mass and motion of globulettes in the Rosette Nebula

    Science.gov (United States)

    Gahm, G. F.; Persson, C. M.; Mäkelä, M. M.; Haikala, L. K.

    2013-07-01

    Context. Tiny molecular clumps are abundant in many H ii regions surrounding newborn stellar clusters. In optical images these so-called globulettes appear as dark patches against the background of bright nebulosity. The majority of the globulettes were found to be of planetary mass in a previous optical investigation, while the largest objects may contain more than half a solar mass. Aims: We aim to clarify the physical nature of globulettes by deriving densities and masses, and to determine their velocities as a function of position over the nebula. This information will provide clues to the question of origins, evolution, and fate of globulettes. The Rosette Nebula is relatively rich in globulettes, and we selected a sample of well-confined objects of different sizes for the present investigation. Methods: Radio observations were made of molecular line emission from 16 globulettes combined with near-infrared (NIR) broad-band JHKs and narrow-band Paschen β and H2 imaging. Ten objects, for which we collected information from several transitions in 12CO and 13CO, were modelled using a spherically symmetric model. Results: Practically all globulettes were detected in our CO survey. The observed 12CO (3-2) and (2-1) line temperatures range from 0.6 K to 6 K, the 13CO being a third of this. As a rule, the lines are narrow, ~1.0 km s-1. The best fit to observed line ratios and intensities was obtained by assuming a model composed of a cool and dense centre and warm and dense surface layer. This model provides estimates of maximum and minimum mass; the average masses range from about 50 to 500 Jupiter masses, which is similar to earlier estimates based on extinction measures. The selected globulettes are dense, nH ~ 104 cm-3, with very thin layers of fluorescent H2 emission, showing that the gas is in molecular form just below the surface. The NIR data show that several globulettes are very opaque and contain dense cores. No infrared-excess stars in the fields are

  1. The UV (IUE) spectrum of the planetary nebula PC 11 (HD 149427)

    NARCIS (Netherlands)

    Parthasarathy, M; Garcia-Lario, P; Pottasch, [No Value; de Martino, D; Surendiranath, R

    The UV spectrum of PC 11 is found to show variations in the strength of the O III] 1666 Angstrom, N III] 1750 Angstrom and C III] 1909 Angstrom emission lines. The detection of continuum emission in the wavelength interval 2650 Angstrom to 3200 Angstrom indicates that the central star of PC 11 has

  2. The lbv phase of the planetary nebula lmc-n66

    OpenAIRE

    M. Peña

    2002-01-01

    Observaciones recientes de la estrella central de la nebulosa planetaria LMC-N66 muestran que el fuerte viento tipo LBV ha estado disminuyendo lentamente, despu es del violento m aximo de 1994. La magnitud actual (mV 18:1 mag) y la probable tasa de p erdida de masa de la estrella son similares a los valores de 1990. A partir de espectros de rendija larga obtenidos con el espectr ografo STIS del Telescopio Espacial Hubble, se han podido analizar algunos datos nebulares.

  3. Testing the nature of SO galaxies using planetary nebula kinematics in NGC 1023

    NARCIS (Netherlands)

    Noordermeer, E.; Merrifield, M. R.; Coccato, L.; Arnaboldi, M.; Capaccioli, M.; Douglas, N. G.; Freeman, K. C.; Gerhard, O.; Kuijken, K.; De Lorenzi, F.; Napolitano, N. R.; Romanowsky, A. J.

    2008-01-01

    We investigate the manner in which lenticular galaxies are formed by studying their stellar kinematics: an S0 formed from a fading spiral galaxy should display similar cold outer disc kinematics to its progenitor, while an S0 formed in a minor merger should be more dominated by random motions. In a

  4. An Expanding Radio Nebula Produced by a Giant Flare from the Magnetar SGR 1806-20

    Energy Technology Data Exchange (ETDEWEB)

    Gaensler, B.

    2005-03-04

    Soft gamma repeaters (SGRs) are ''magnetars'', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B {approx} 10{sup 15} gauss. On 2004 December 27, a giant flare was detected from the magnetar SGR 1806-20, the third such event ever recorded. This burst of energy was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere recorded around the globe. Here we report the detection of a fading radio afterglow produced by this outburst, with a luminosity 500 times larger than the only other detection of a similar source. From day 6 to day 19 after the flare from SGR 1806-20, a resolved, linearly polarized, radio nebula was seen, expanding at approximately a quarter the speed of light. To create this nebula, at least 4 x 10{sup 43} ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles. The combination of spatially resolved structure and rapid time evolution allows a study in unprecedented detail of a nearby analog to supernovae and gamma-ray bursts.

  5. Radiation emitting devices regulations

    International Nuclear Information System (INIS)

    1970-01-01

    The Radiation Emitting Devices Regulations are the regulations referred to in the Radiation Emitting Devices Act and relate to the operation of devices. They include standards of design and construction, standards of functioning, warning symbol specifications in addition to information relating to the seizure and detention of machines failing to comply with the regulations. The radiation emitting devices consist of the following: television receivers, extra-oral dental x-ray equipment, microwave ovens, baggage inspection x-ray devices, demonstration--type gas discharge devices, photofluorographic x-ray equipment, laser scanners, demonstration lasers, low energy electron microscopes, high intensity mercury vapour discharge lamps, sunlamps, diagnostic x-ray equipment, ultrasound therapy devices, x-ray diffraction equipment, cabinet x-ray equipment and therapeutic x-ray equipment

  6. OpenNebula KVM SR-IOV driver

    CSIR Research Space (South Africa)

    Macleod, D

    2013-05-01

    Full Text Available Version: 0.1 License: Apache 2.0 Web Links: Project Website: http://wiki.chpc.ac.za/acelab:opennebula_sr-iov_vmm_driver Demonstration Video: http://www.youtube.com/watch?v=wB-Z1o2jGaY OpenNebula Page: http...://opennebula.org/software:ecosystem:sr-iov Prerequisites and Limitations 1. This driver has been developed to support OpenNebula 4.0 and KVM. The driver should be backwards compatible the OpenNebula 3.x. 2. SR-IOV capable hardware and software is required. Before using...

  7. X-ray Emission from the Guitar Nebula

    OpenAIRE

    Romani, Roger W.; Cordes, James M.; Yadigaroglu, I. -A.

    1997-01-01

    We have detected weak soft X-ray emission from the Pulsar Wind Nebula trailing the high velocity star PSR 2224+65 (the `Guitar Nebula'). This X-ray flux gives evidence of \\gamma~10^7 eV particles in the pulsar wind and constrains the properties of the post-shock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near equipartition values.

  8. X-Ray Emission from the Guitar Nebula

    Science.gov (United States)

    Romani, Roger W.; Cordes, James M.; Yadigaroglu, I.-A.

    1997-01-01

    We have detected weak soft X-ray emission from the pulsar wind nebula trailing the high-velocity star PSR 2224+65 (the "Guitar Nebula"). This X-ray flux gives evidence of gamma approximately 10(exp 7) eV particles in the pulsar wind and constrains the properties of the postshock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near-equipartition values.

  9. Transition radiation and peculiar nebulas. [Emission lines, color indices

    Energy Technology Data Exchange (ETDEWEB)

    Gurzadyan, G.A.

    1975-01-01

    The transition radiation resulting from the electrodynamic interaction of fast electrons with dust particles may explain certain observations for peculiar galactic nebulas--Herbig--Haro objects, cometary nebulas, nebulas of the Barnard 10 type, T Tauri stars, FU Ori stars, etc. Equations are derived for the energetic and physical properties of peculiar objects. The probable energy of the fast electrons turns out to be on the order of 1.5 MeV. The excitation of emission lines, the color indices in the case of transition radiation, etc., are also discussed. A possible application of this theory to FUOR's is pointed out.

  10. Annual review of earth and planetary sciences. Volume 16

    Science.gov (United States)

    Wetherill, George W.; Albee, Arden L.; Stehli, Francis G.

    Various papers on earth and planetary science topics are presented. The subjects addressed include: role and status of earth science field work; phase relations of prealuminous granitic rocks and their petrogenetic implications; chondritic meteorites and the solar nebula; volcanic winters; mass wasting on continental margins; earthquake ground motions; ore deposits as guides to geologic history of the earth; geology of high-level nuclear waste disposal; and tectonic evolution of the Caribbean. Also discussed are: the earth's rotation; the geophysics of a restless caldera (Long Valley, California); observations of cometary nuclei; geology of Venus; seismic stratigraphy; in situ-produced cosmogenic isotopes in terrestrial rocks; time variations of the earth's magnetic field; deep slabs, geochemical heterogeneity, and the large-scale structure of mantle convection; early proterozoic assembly and growth of Laurentia; concepts and methods of high-resolution event stratigraphy.

  11. A HST/WFC3 Search for Substellar Companions in the Orion Nebula Cluster

    Science.gov (United States)

    Strampelli, Giovanni Maria; Aguilar, Jonathan; Aparicio, Antonio; Piotto, Giampaolo; Pueyo, Laurent; Robberto, Massimo

    2018-01-01

    We present new results relative to the population of substellar binaries in the Orion Nebula Cluster. We reprocessed HST/WFC3 data using an analysis technique developed to detect close companions in the wings of the stellar PSFs, based on the PyKLIP implementation of the KLIP PSF subtraction algorithm. Starting from a sample of ~1200 stars selected over the range J=11-15 mag, we were able to uncover ~80 candidate companions in the magnitude range J=16-23 mag. We use the presence of the 1.4 micron H2O absorption feature in the companion photosphere to discriminate 32 bona-fide substellar candidates from a population of reddened background objects. We derive an estimate of the companion mass assuming a 2Myr isochrone and the reddening of their primary. With 8 stellar companions, 19 brown dwarfs and 5 planetary mass objects, our study provide us with an unbiased sample of companions at the low-mass end of the IMF, probing the transition from binary to planetary systems.

  12. Planetary seismology and interiors

    Science.gov (United States)

    Toksoz, M. N.

    1979-01-01

    This report briefly summarizes knowledge gained in the area of planetary seismology in the period 1969-1979. Attention is given to the seismic instruments, the seismic environment (noise, characteristics of seismic wave propagation, etc.), and the seismicity of the moon and Mars as determined by the Apollo missions and Viking Lander experiments, respectively. The models of internal structures of the terrestrial planets are discussed, with the earth used for reference.

  13. Galactic planetary science.

    Science.gov (United States)

    Tinetti, Giovanna

    2014-04-28

    Planetary science beyond the boundaries of our Solar System is today in its infancy. Until a couple of decades ago, the detailed investigation of the planetary properties was restricted to objects orbiting inside the Kuiper Belt. Today, we cannot ignore that the number of known planets has increased by two orders of magnitude nor that these planets resemble anything but the objects present in our own Solar System. Whether this fact is the result of a selection bias induced by the kind of techniques used to discover new planets--mainly radial velocity and transit--or simply the proof that the Solar System is a rarity in the Milky Way, we do not know yet. What is clear, though, is that the Solar System has failed to be the paradigm not only in our Galaxy but even 'just' in the solar neighbourhood. This finding, although unsettling, forces us to reconsider our knowledge of planets under a different light and perhaps question a few of the theoretical pillars on which we base our current 'understanding'. The next decade will be critical to advance in what we should perhaps call Galactic planetary science. In this paper, I review highlights and pitfalls of our current knowledge of this topic and elaborate on how this knowledge might arguably evolve in the next decade. More critically, I identify what should be the mandatory scientific and technical steps to be taken in this fascinating journey of remote exploration of planets in our Galaxy.

  14. Light-Emitting Pickles

    Science.gov (United States)

    Vollmer, M.; Mollmann, K-P.

    2015-01-01

    We present experiments giving new insights into the classical light-emitting pickle experiment. In particular, measurements of the spectra and temperatures, as well as high-speed recordings, reveal that light emission is connected to the polarity of the electrodes and the presence of hydrogen.

  15. Possible mass distributions in the nebulae of other solar systems

    International Nuclear Information System (INIS)

    Brown, W.K.

    1987-01-01

    The supernova shell fragmentation model of solar system formation - previously shown to be successful in describing the mass distribution of our solar system - is used to calculate the mass distributions of other solar nebulae. (Auth.)

  16. The [NeIV] Lines in High Excitation Gaseous Nebulae.

    Science.gov (United States)

    Aller, L H

    1970-04-01

    The "forbidden" lines of three times ionized neon are among the most precious indicators of electron temperature and excitation. They are also predicted to be among the strongest lines observed in the far ultraviolet spectra of high excitation nebulae.

  17. The carbon budget in the outer solar nebula

    International Nuclear Information System (INIS)

    Simonelli, D.P.; Pollack, J.B.; Mckay, C.P.; Reynolds, R.T.; Summers, A.L.

    1989-01-01

    The compositional contrast between the giant-planet satellites and the significantly rockier Pluto/Charon system is indicative of different formation mechanisms; cosmic abundance calculations, in conjunction with an assumption of the Pluto/Charon system's direct formation from solar nebula condensates, strongly suggest that most of the carbon in the outer solar nebula was in CO form, in keeping with both the inheritance from the dense molecular clouds in the interstellar medium, and/or the Lewis and Prinn (1980) kinetic-inhibition model of solar nebula chemistry. Laboratory studies of carbonaceous chondrites and Comet Halley flyby studies suggest that condensed organic material, rather than elemental carbon, is the most likely candidate for the small percentage of the carbon-bearing solid in the outer solar nebula. 71 refs

  18. Interpretation of the [ClIII] Lines in Gaseous Nebulae.

    Science.gov (United States)

    Aller, L H; Czyzak, S J; Walker, M F; Krueger, T K

    1970-05-01

    The intensity ratio of the green lambdalambda5517 and 5537 lines of [ClIII] serves as an indicatrix of the electron density in many gaseous nebulae whose spectra can be observed with an image converter. Quantitative interpretation of the line ratio requires accurate values of the collisional strengths and transition probabilities. With improved values of these parameters we have revised electron densities for a number of nebulae; the results seem to be in good accord with those derived from other criteria.

  19. The Variable Crab Nebula: Evidence for a Connection Between GeV Flares and Hard X-ray Variations

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Harding, A. K.; Hays, E. A.; Cherry, M. L.; Case, G. L.; Finger, M. H.; Jenke, P.; Zhang, X.

    2016-01-01

    In 2010, hard X-ray variations (Wilson-Hodge et al. 2011) and GeV flares (Tavani et al 2011, Abdo et al. 2011) from the Crab Nebula were discovered. Connections between these two phenomena were unclear, in part because the timescales were quite different, with yearly variations in hard X-rays and hourly to daily variations in the GeV flares. The hard X-ray flux from the Crab Nebula has again declined since 2014, much like it did in 2008-2010. During both hard X-ray decline periods, the Fermi LAT detected no GeV flares, suggesting that injection of particles from the GeV flares produces the much slower and weaker hard X-ray variations. The timescale for the particles emitting the GeV flares to lose enough energy to emit synchrotron photons in hard X-rays is consistent with the yearly variations observed in hard X-rays and with the expectation that the timescale for variations slowly increases with decreasing energy. This hypothesis also predicts even slower and weaker variations below 10 keV, consistent with the non-detection of counterparts to the GeV flares by Chandra (Weisskopf et al 2013). We will present a comparison of the observed hard X-ray variations and a simple model of the decay of particles from the GeV flares to test our hypothesis.

  20. The Orion Nebula: Still Full of Surprises

    Science.gov (United States)

    2011-01-01

    This ethereal-looking image of the Orion Nebula was captured using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory, Chile. This nebula is much more than just a pretty face, offering astronomers a close-up view of a massive star-forming region to help advance our understanding of stellar birth and evolution. The data used for this image were selected by Igor Chekalin (Russia), who participated in ESO's Hidden Treasures 2010 astrophotography competition. Igor's composition of the Orion Nebula was the seventh highest ranked entry in the competition, although another of Igor's images was the eventual overall winner. The Orion Nebula, also known as Messier 42, is one of the most easily recognisable and best-studied celestial objects. It is a huge complex of gas and dust where massive stars are forming and is the closest such region to the Earth. The glowing gas is so bright that it can be seen with the unaided eye and is a fascinating sight through a telescope. Despite its familiarity and closeness there is still much to learn about this stellar nursery. It was only in 2007, for instance, that the nebula was shown to be closer to us than previously thought: 1350 light-years, rather than about 1500 light-years. Astronomers have used the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile to observe the stars within Messier 42. They found that the faint red dwarfs in the star cluster associated with the glowing gas radiate much more light than had previously been thought, giving us further insights into this famous object and the stars that it hosts. The data collected for this science project, with no original intention to make a colour image, have now been reused to create the richly detailed picture of Messier 42 shown here. The image is a composite of several exposures taken through a total of five different filters. Light that passed through a red filter as well as light from a filter that

  1. Robotic Planetary Drill Tests

    Science.gov (United States)

    Glass, Brian J.; Thompson, S.; Paulsen, G.

    2010-01-01

    Several proposed or planned planetary science missions to Mars and other Solar System bodies over the next decade require subsurface access by drilling. This paper discusses the problems of remote robotic drilling, an automation and control architecture based loosely on observed human behaviors in drilling on Earth, and an overview of robotic drilling field test results using this architecture since 2005. Both rotary-drag and rotary-percussive drills are targeted. A hybrid diagnostic approach incorporates heuristics, model-based reasoning and vibration monitoring with neural nets. Ongoing work leads to flight-ready drilling software.

  2. Signatures of Chemical Evolution in Protostellar Nebulae

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha

    2011-01-01

    A decade ago observers began to take serious notice of the presence of crystalline silicate grains in the dust flowing away from some comets. While crystallinity had been seen in such objects previously, starting with the recognitions by Campins and Ryan (1990) that the 10 micron feature of Comet Halley resembled that of the mineral forsterite, most such observations were either ignored or dismissed as no path to explain such crystalline grains was available in the literature. When it was first suggested that an outward flow must be present to carry annealed silicate grains from the innermost regions of the Solar Nebula out to the regions where comets could form (Nuth, 1999; 2001) this suggestion was also dismissed because no such transport mechanism was known at the time. Since then not only have new models of nebular dynamics demonstrated the reality of long distance outward transport (Ciesla, 2007; 2008; 2009) but examination of older models (Boss, 2004) showed that such transport had been present but had gone unrecognized for many years. The most unassailable evidence for outward nebular transport came with the return of the Stardust samples from Comet Wild2, a Kuiper-belt comet that contained micron-scale grains of high temperature minerals resembling the Calcium-Aluminum Inclusions found in primitive meteorites (Zolensky et aI., 2006) that formed at T > 1400K. Now that outward transport in protostellar nebulae has been firmly established, a re-examination of its consequences for nebular gas is in order that takes into account both the factors that regulate both the outward flow as well as those that likely control the chemical composition of the gas. Laboratory studies of surface catalyzed reactions suggest that a trend toward more highly reduced carbon and nitrogen compounds in the gas phase should be correlated with a general increase in the crystallinity of the dust (Nuth et aI., 2000), but is such a trend actually observable? Unlike the Fischer-Tropsch or

  3. PLANETARY EMBRYO BOW SHOCKS AS A MECHANISM FOR CHONDRULE FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Christopher R.; Boley, Aaron C. [Department of Physics and Astronomy University of British Columbia Vancouver, BC V6T 1Z1 (Canada); Morris, Melissa A. [Physics Department State University of New York at Cortland Cortland, NY 13045 (United States)

    2016-02-20

    We use radiation hydrodynamics with direct particle integration to explore the feasibility of chondrule formation in planetary embryo bow shocks. The calculations presented here are used to explore the consequences of a Mars-size planetary embryo traveling on a moderately excited orbit through the dusty, early environment of the solar system. The embryo’s eccentric orbit produces a range of supersonic relative velocities between the embryo and the circularly orbiting gas and dust, prompting the formation of bow shocks. Temporary atmospheres around these embryos, which can be created via volatile outgassing and gas capture from the surrounding nebula, can non-trivially affect thermal profiles of solids entering the shock. We explore the thermal environment of solids that traverse the bow shock at different impact radii, the effects that planetoid atmospheres have on shock morphologies, and the stripping efficiency of planetoidal atmospheres in the presence of high relative winds. Simulations are run using adiabatic and radiative conditions, with multiple treatments for the local opacities. Shock speeds of 5, 6, and 7 km s{sup −1} are explored. We find that a high-mass atmosphere and inefficient radiative conditions can produce peak temperatures and cooling rates that are consistent with the constraints set by chondrule furnace studies. For most conditions, the derived cooling rates are potentially too high to be consistent with chondrule formation.

  4. Dynamical evolution of the Orion nebula cluster

    Science.gov (United States)

    Scally, Aylwyn; Clarke, Cathie; McCaughrean, Mark J.

    2005-04-01

    Observations of star formation in the Galaxy support the conclusion that most stars - including our own - form in an environment like the Orion nebula cluster (ONC). We construct a range of dynamical models of the ONC, using Aarseth's NBODY6 code, and explore their consequences for the origins of the cluster and its subsequent evolution. We find that the most acceptable fits to the cluster density profile are obtained in models where the cluster is set up in virial equilibrium and where the cluster extends well outside the limits of existing photometric surveys. However, current estimates of the virial ratio suggest the cluster is already unbound. We show that the size and age of the ONC in this case imply either that it became unbound only very recently, or else that it has expanded quasi-statically. In the latter case, its initial central density may have exceeded its current value by 1-2 orders of magnitude. We stress the importance of future proper motion experiments to distinguish between these possibilities.

  5. The Rapid Evolution of the Exciting Star of the Stingray Nebula

    Science.gov (United States)

    Reindl, N.; Rauch, T.; Parthasarathy, M.; Werner, K.; Kruk, J.W.; Hamann, W. R.; Sander, A.; Todt, H.

    2014-01-01

    . Alternatively, it could be the outcome of close-binary evolution. Then SAO244567 would be a low-mass (0.354 solar mass) helium pre-white dwarf after the common-envelope phase, during which the planetary nebula was ejected.

  6. Further considerations on contracting solar nebula

    International Nuclear Information System (INIS)

    Rawal, J.J.

    1986-01-01

    Prentice (1978) in his modern Laplacian theory of the origin of the solar system established the scenario of the formation of the solar system on the basis of the usual laws of conservation of mass and angular momentum and the concept of supersonic turbulent convection. This provides a physical understanding of the Titius-Bode law of planetary distances. Starting with the concept of the Roche limit, the author derives a similar relation and discusses Kepler's third law in relation to this concept. He also discusses the resonant structure in the solar system in this context. (Auth.)

  7. Planetary Sciences and Exploration Programme

    Indian Academy of Sciences (India)

    The Indian Space Research Organisation (ISRO) has taken a number of initiatives to plan for a National. Research Programme in the area of planetary science and exploration. This announcement solicits proposals in the field of planetary science. Universities, research and educational institutions may submit proposals ...

  8. IDENTIFICATION OF THREE NEW PROTOPLANETARY NEBULAE EXHIBITING THE UNIDENTIFIED FEATURE AT 21 μm

    International Nuclear Information System (INIS)

    Cerrigone, Luciano; Hora, Joseph L.; Hart, Alexa; Fazio, Giovanni; Umana, Grazia; Trigilio, Corrado

    2011-01-01

    Among its great findings, the Infrared Astronomical Satellite mission showed the existence of an unidentified mid-IR feature around 21 μm. Since its discovery, this feature has been detected in all C-rich protoplanetary nebulae (PPNe) of intermediate spectral type (F-G) and-weakly-in a few PNe and asymptotic giant branch (AGB) stars, but the nature of its carriers remains unknown. In this paper, we show the detection of this feature in the spectra of three new stars transiting from the AGB to the PN stage obtained with the Spitzer Space Telescope. Following a recent suggestion, we try to model the spectral energy distributions of our targets with amorphous carbon and FeO, which might be responsible for the unidentified feature. The fit thus obtained is not completely satisfactory, since the shape of the feature is not well matched. In an attempt to relate the unidentified feature to other dust features, we retrieved mid-IR spectra of all 21 μm sources currently known from Infrared Space Observatory and Spitzer online archives and noticed a correlation between the flux emitted in the 21 μm feature and that emitted at 7 and 11 μm (polycyclic aromatic hydrocarbon bands and hydrogenated amorphous carbon broad emission). Such a correlation may point to a common nature of the carriers.

  9. A turbulent two-phase flow model for nebula flows

    International Nuclear Information System (INIS)

    Champney, J.M.; Cuzzi, J.N.

    1990-01-01

    A new and very efficient turbulent two-phase flow numericaly model is described to analyze the environment of a protoplanetary nebula at a stage prior to the formation of planets. Focus is on settling processes of dust particles in flattened gaseous nebulae. The model employs a perturbation technique to improve the accuracy of the numerical simulations of such flows where small variations of physical quantities occur over large distance ranges. The particles are allowed to be diffused by gas turbulence in addition to settling under gravity. Their diffusion coefficients is related to the gas turbulent viscosity by the non-dimensional Schmidt number. The gas turbulent viscosity is determined by the means of the eddy viscosity hypothesis that assumes the Reynolds stress tensor proportional to the mean strain rate tensor. Zero- and two-equation turbulence models are employed. Modeling assumptions are detailed and discussed. The numerical model is shown to reproduce an existing analytical solution for the settling process of particles in an inviscid nebula. Results of nebula flows are presented taking into account turbulence effects of nebula flows. Diffusion processes are found to control the settling of particles. 24 refs

  10. Spectral and interferometric observation of four emission nebulas

    International Nuclear Information System (INIS)

    Lozinskaya, T.A.; Klement'eva, A.Yu.; Zhukov, G.V.; Shenavrin, V.I.

    1975-01-01

    Results of spectrophotometric and interferometric observations of four emission nebulae are presented; electron temperature Te and electron density Ne are estimated; mean beam velocities and parameters of the internal motion in the nebylae are determined. The following objects have been investigated: 1) a bright compact nebulae of unknown nature 2.5 in size which is identified with the non-thermal radiosource G6.4-0.5 in the region W28; 2) nebulae RCW171 5' in size which is identified with the radiosource G23.1+0.6; 3) the nebulae Simeiz 34/Sharpless 261/d 1950 =6sup(h)05sup(m), sigma 1950 =+15 deg 49'; its diameter is approximately 30 an extensive complex of bright emission fibres in the nebulae Swan, which are partially projected into a possible remainder of the outburst of a supernova W63; L 1950 =20sup(h)17sup(m); S 1950 =45 deg 30' its diameter is approximately 1 deg 5

  11. Continuous emission from the gaseous nebula beyond the Lyman limit

    International Nuclear Information System (INIS)

    Bolgova, G.T.; Khromov, G.S.

    1975-01-01

    Models of spherically-symmetric isothermic hydrogen nebula with an exciting star in the centre are considered. Spectra and energies of diffuse radiation of nebula and of direct radiation of its kernel are calculated in the Lyman continuum for the external boundary of the object. The spectrum of the diffuse radiation is shown to be to a great extent invariant in relation to all parameters of models except for Tsub(e). The total loss in energy of Lsub(c)-radiation of kernel through the external border of the ionized nebula, amounts to 20-30% in the average even at a considerable optical thickness of the object tausub(0). The greater part of this energy is transferred via direct ionizing radiation, though the relative contribution of the diffuse Lsub(c)-radiation of nebula reaches 30% at low temperatures of the exciting star and at large tausub(0). The results of this work may be applied to calculating the energy balance of the star-nebula system, the heating of dust particles and ionization of the neighbouring interstellar medium, and also for determining the conditions of observation of the far ultra-violet radiation of similar objects

  12. The discovery of a highly polarized bipolar nebula

    International Nuclear Information System (INIS)

    Wolstencroft, R.D.; Scarrott, S.M.; Menzies, J.

    1989-01-01

    During a search for the optical counterparts of IRAS sources whose flux peaks at 25 microns, a small faint bipolar nebula was discovered in Monoceros at the position of IRAS 07131-0147. The CCD images display the object's considerable structure. The central star seems relatively free of closeby nebulosity: the two lobes have a bow-tie structure with those parts nearest to the star consisting of series of small knots. The outer parts of the lobes seem to be made up of filaments streaming away from knots. On the basis of its optical spectrum, the central star was classified as a M5-6 giant. In the IRAS color classification scheme of Van der Veen and Habing (1988), the central star is VIb which indicates that there are distinct hot and cold components of circumstellar dust and that the mass loss process may have temporarily abated. Therefore, it is proposed that the object is in the post main sequence stage of evolution and is a protoplanetary nebulae. Young protoplanetary nebulae have totally obscured central stars illuminating reflective lobes whereas older ones such as M2-9 have lobes seen in emission from gas ionized by the central hot star which is clearly visible. Since the central object of IRAS07131-0147 is a relatively unobscured late type star and the lobes are seen only by reflection, it is suggested that this nebula is a protoplanetary nebula in an evolutionary stage intermediate between that of CRL2688 and M2-9

  13. On the injection of relativistic particles into the Crab Nebula

    International Nuclear Information System (INIS)

    Shklovskij, I.S.

    1977-01-01

    It is shown that a flux of relativistic electrons from the NP 0532 pulsar magnetosphere, responsible for its synchrotron emission, cannot provide the necessary energy pumping to the Crab Nebula. A conclusion is reached that such a pumping can be effectuated by a flow of relativistic electrons leaving the NP 0532 magnetosphere at small pitch angles and giving therefore no appreciable contribution to the synchrotron emission of the pulsar. An interpretation of the Crab Nebula synchrotron spectrum is given on the assumption of secular ''softening'' of the energy spectrum of the relativistic electrons injected into the Nebula. A possibility of explanation of the observed rapid variability of some features in the central part of the Nebula by ejection of free - neutron - rich dense gas clouds from the pulsar surface during ''starquakes'' is discussed. The clouds of rather dense (nsub(e) approximately 10 7 cm -3 ) plasma, thus formed at about 10 13 cm from pulsar, will be accelerated up to relativistic velocities by the pressure of the magneto-dipole radiation of NP 0532 and will deform the magnetic field in the inner part (R 17 cm) of the Crab Nebula, that is the cause of the variability observed. In this case, favourable conditions for the acceleration of the particles in the cloud up to relativistic energies are realized; that may be an additional source of injection

  14. Technology under Planetary Protection Research (PPR)

    Data.gov (United States)

    National Aeronautics and Space Administration — Planetary protection involves preventing biological contamination on both outbound and sample return missions to other planetary bodies. Numerous areas of research...

  15. Planetary heat flow measurements.

    Science.gov (United States)

    Hagermann, Axel

    2005-12-15

    The year 2005 marks the 35th anniversary of the Apollo 13 mission, probably the most successful failure in the history of manned spaceflight. Naturally, Apollo 13's scientific payload is far less known than the spectacular accident and subsequent rescue of its crew. Among other instruments, it carried the first instrument designed to measure the flux of heat on a planetary body other than Earth. The year 2005 also should have marked the launch of the Japanese LUNAR-A mission, and ESA's Rosetta mission is slowly approaching comet Churyumov-Gerasimenko. Both missions carry penetrators to study the heat flow from their target bodies. What is so interesting about planetary heat flow? What can we learn from it and how do we measure it?Not only the Sun, but all planets in the Solar System are essentially heat engines. Various heat sources or heat reservoirs drive intrinsic and surface processes, causing 'dead balls of rock, ice or gas' to evolve dynamically over time, driving convection that powers tectonic processes and spawns magnetic fields. The heat flow constrains models of the thermal evolution of a planet and also its composition because it provides an upper limit for the bulk abundance of radioactive elements. On Earth, the global variation of heat flow also reflects the tectonic activity: heat flow increases towards the young ocean ridges, whereas it is rather low on the old continental shields. It is not surprising that surface heat flow measurements, or even estimates, where performed, contributed greatly to our understanding of what happens inside the planets. In this article, I will review the results and the methods used in past heat flow measurements and speculate on the targets and design of future experiments.

  16. Solar planetary systems stardust to terrestrial and extraterrestrial planetary sciences

    CERN Document Server

    Bhattacharya, Asit B

    2017-01-01

    The authors have put forth great efforts in gathering present day knowledge about different objects within our solar system and universe. This book features the most current information on the subject with information acquired from noted scientists in this area. The main objective is to convey the importance of the subject and provide detailed information on the physical makeup of our planetary system and technologies used for research. Information on educational projects has also been included in the Radio Astronomy chapters.This information is a real plus for students and educators considering a career in Planetary Science or for increasing their knowledge about our planetary system

  17. Layers in the Central Orion Nebula

    Science.gov (United States)

    O'Dell, C. R.

    2018-04-01

    The existence of multiple layers in the inner Orion Nebula has been revealed using data from an Atlas of spectra at 2″ and 12 km s-1 resolution. These data were sometimes grouped over Samples of 10″×10″ to produce high Signal to Noise spectra and sometimes grouped into sequences of pseudo-slit Spectra of 12{^''.}8 - 39″width for high spatial resolution studies. Multiple velocity systems were found: V_{MIF} traces the Main Ionization Front (MIF), V_{scat} arises from back-scattering of V_{MIF} emission by particles in the background Photon Dissociation Region (PDR), V_{low} is an ionized layer in front of the MIF and if it is the source of the stellar absorption lines seen in the Trapezium stars, it must lie between the foreground Veil and those stars, V_{new,[O III]} may represent ionized gas evaporating from the Veil away from the observer. There are features such as the Bright Bar where variations of velocities are due to changing tilts of the MIF, but velocity changes above about 25″ arise from variations in velocity of the background PDR. In a region 25″ ENE of the Orion-S Cloud one finds dramatic changes in the [O III] components, including the signals from the V_{low,[O III]} and V_{MIF,[O III]} becoming equal, indicating shadowing of gas from stellar photons of >24.6 eV. This feature is also seen in areas to the west and south of the Orion-S Cloud.

  18. Facilitating NASA Earth Science Data Processing Using Nebula Cloud Computing

    Science.gov (United States)

    Chen, A.; Pham, L.; Kempler, S.; Theobald, M.; Esfandiari, A.; Campino, J.; Vollmer, B.; Lynnes, C.

    2011-12-01

    Cloud Computing technology has been used to offer high-performance and low-cost computing and storage resources for both scientific problems and business services. Several cloud computing services have been implemented in the commercial arena, e.g. Amazon's EC2 & S3, Microsoft's Azure, and Google App Engine. There are also some research and application programs being launched in academia and governments to utilize Cloud Computing. NASA launched the Nebula Cloud Computing platform in 2008, which is an Infrastructure as a Service (IaaS) to deliver on-demand distributed virtual computers. Nebula users can receive required computing resources as a fully outsourced service. NASA Goddard Earth Science Data and Information Service Center (GES DISC) migrated several GES DISC's applications to the Nebula as a proof of concept, including: a) The Simple, Scalable, Script-based Science Processor for Measurements (S4PM) for processing scientific data; b) the Atmospheric Infrared Sounder (AIRS) data process workflow for processing AIRS raw data; and c) the GES-DISC Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI) for online access to, analysis, and visualization of Earth science data. This work aims to evaluate the practicability and adaptability of the Nebula. The initial work focused on the AIRS data process workflow to evaluate the Nebula. The AIRS data process workflow consists of a series of algorithms being used to process raw AIRS level 0 data and output AIRS level 2 geophysical retrievals. Migrating the entire workflow to the Nebula platform is challenging, but practicable. After installing several supporting libraries and the processing code itself, the workflow is able to process AIRS data in a similar fashion to its current (non-cloud) configuration. We compared the performance of processing 2 days of AIRS level 0 data through level 2 using a Nebula virtual computer and a local Linux computer. The result shows that Nebula has significantly

  19. Ring-shaped nebulae around FU Orionis stars

    International Nuclear Information System (INIS)

    Goodrich, R.W.

    1987-01-01

    Observational data on the morphology and spectra of the nebulae surrounding V1057 Cyg, V1515 Cyg, and V1735 Cyg stars are presented and studied. The data reveal that V1735 Cyg is more highly reddened than the nebula and the spectra of all three nebulae are from reflection. A simple model for the dust shell is proposed and it is argued that the shells may indicate a relatively advanced evolutionary state for the FU Orionis star. The relation between the shells and the evolution of the stars is examined. The models of Herbig (1977), Mould et al. (1978), Larson (1980), and Hartmann and Kenyon (1985), which are utilized to analyze the FU Orionis outburst phenomenon, are tested. 23 references

  20. Planetary Landscape Geography

    Science.gov (United States)

    Hargitai, H.

    INTRODUCTION Landscape is one of the most often used category in physical ge- ography. The term "landshap" was introduced by Dutch painters in the 15-16th cen- tury. [1] The elements that build up a landscape (or environment) on Earth consists of natural (biogenic and abiogenic - lithologic, atmospheric, hydrologic) and artificial (antropogenic) factors. Landscape is a complex system of these different elements. The same lithology makes different landscapes under different climatic conditions. If the same conditions are present, the same landscape type will appear. Landscapes build up a hierarchic system and cover the whole surface. On Earth, landscapes can be classified and qualified according to their characteristics: relief forms (morphology), and its potential economic value. Aesthetic and subjective parameters can also be considered. Using the data from landers and data from orbiters we can now classify planetary landscapes (these can be used as geologic mapping units as well). By looking at a unknown landscape, we can determine the processes that created it and its development history. This was the case in the Pathfinder/Sojourner panoramas. [2]. DISCUSSION Planetary landscape evolution. We can draw a raw landscape develop- ment history by adding the different landscape building elements to each other. This has a strong connection with the planet's thermal evolution (age of the planet or the present surface materials) and with orbital parameters (distance from the central star, orbit excentricity etc). This way we can build a complex system in which we use differ- ent evolutional stages of lithologic, atmospheric, hydrologic and biogenic conditions which determine the given - Solar System or exoplanetary - landscape. Landscape elements. "Simple" landscapes can be found on asteroids: no linear horizon is present (not differentiated body, only impact structures), no atmosphere (therefore no atmospheric scattering - black sky as part of the landscape) and no

  1. Excimer laser superficial keratectomy for proud nebulae in keratoconus.

    Science.gov (United States)

    Moodaley, L; Liu, C; Woodward, E G; O'Brart, D; Muir, M K; Buckley, R

    1994-06-01

    Contact lens intolerance in keratoconus may be due to the formation of a proud nebula at or near the apex of the cone. Excimer laser superficial keratectomy was performed as an outpatients with proud nebulae as treatment patients with proud nebulae as treatment for their contact lens intolerance. The mean period of contact lens wear before the development of intolerance was 13.4 years (range 2 to 27 years). Following the development of intolerance, three patients abandoned contact lens wear in the affected eye while the remainder experienced a reduction in comfortable wearing time (mean = 3.75 hours; range: 0-14 hours). All patients had good potential Snellen visual acuity with a contact lens of 6/9 (nine eyes) and 6/12 (one eye). The proud nebulae were directly ablated with a 193 nm ArF excimer laser using a 1 mm diameter beam. Between 100-150 pulses were sufficient to ablate the raised area. Patients experienced no pain during the procedure and reported minimal discomfort postoperatively. In all cases flattening of the proud nebulae was achieved. Seven patients were able to resume regular contact lens wear (mean wearing time = 10.17 hours; range 8 to 16 hours). In three patients, resumption of contact lens wear was unsuccessful because of cone steepness. All patients achieved postoperative Snellen visual acuity of 6/12 or better with a contact lens. Four patients experienced a loss of one line in Snellen acuity. The mean follow up period was 8.3 months (range 2 to 17 months). Excimer laser superficial keratectomy is a useful technique for the treatment of contact lens intolerance caused by proud nebulae in patients with keratoconus. Penetrating keratoplasty is thus avoided.

  2. Proper-Motion Measurements of the Cygnus Egg Nebula

    Science.gov (United States)

    Ueta, Toshiya; Murakawa, Koji; Meixner, Margaret

    2006-04-01

    We present the results of proper-motion measurements of the dust shell structure in the Egg Nebula (AFGL 2688, CRL 2688, V1610 Cyg), based on the archived two-epoch data at 2 μm taken with the Hubble Space Telescope. We measured the amount of motion of local structures in the nebula by determining their relative shifts over an interval of 5.5 yr. The dynamical age of the nebula is found to be roughly 350 yr based on the overall Hubble-law-esque motion of the nebula. By adopting the deprojected velocity of 45 km s-1 at the tips of the bipolar lobes, our proper-motion measurements indicate that the distance to the Egg Nebula is about 420 pc and that the lobes are inclined at 7.7d with respect to the plane of the sky. The refined distance estimate yields a luminosity of the central star of 3.3×103 Lsolar, a total shell mass of 1.2 Msolar, and a mass-loss rate (the upper limit) of 3.6×10-3 Msolar yr-1. Assuming a 0.6 Msolar central post-AGB stellar mass, the initial mass of the Egg is 1.8 Msolar. Upon analysis, we also discovered that (1) the central star of the Egg Nebula has a proper motion of its own at a rate of 17 mas yr-1, (2) the tips of the lobes increased their velocity due to shock acceleration, and (3) the apparent bipolar lobes consist of multiple outflows at distinct inclination angles projected onto each other.

  3. Facilitating NASA Earth Science Data Processing Using Nebula Cloud Computing

    Science.gov (United States)

    Pham, Long; Chen, Aijun; Kempler, Steven; Lynnes, Christopher; Theobald, Michael; Asghar, Esfandiari; Campino, Jane; Vollmer, Bruce

    2011-01-01

    Cloud Computing has been implemented in several commercial arenas. The NASA Nebula Cloud Computing platform is an Infrastructure as a Service (IaaS) built in 2008 at NASA Ames Research Center and 2010 at GSFC. Nebula is an open source Cloud platform intended to: a) Make NASA realize significant cost savings through efficient resource utilization, reduced energy consumption, and reduced labor costs. b) Provide an easier way for NASA scientists and researchers to efficiently explore and share large and complex data sets. c) Allow customers to provision, manage, and decommission computing capabilities on an as-needed bases

  4. Observing by hand sketching the nebulae in the nineteenth century

    CERN Document Server

    Nasim, Omar W

    2014-01-01

    Today we are all familiar with the iconic pictures of the nebulae produced by the Hubble Space Telescope's digital cameras. But there was a time, before the successful application of photography to the heavens, in which scientists had to rely on handmade drawings of these mysterious phenomena.           Observing by Hand sheds entirely new light on the ways in which the production and reception of handdrawn images of the nebulae in the nineteenth century contributed to astronomical observation. Omar W. Nasim investigates hundreds of unpublished observing books and paper records from six ninete

  5. Further considerations on contracting solar nebula

    Science.gov (United States)

    Rawal, J. J.

    1986-01-01

    Kepler's third law of the planetary system is analyzed in terms of Prentice's (1978a) modern Laplacian theory and Rawal's (1984) Roche limit concept. Prentice has determined, based on laws of conservation of mass and angular momentum and the concept of supersonic turbulent convection, that the ratio of orbital radii of successively disposed gaseous rings is a constant of approximately 1.69. Rawal studied the relationship between the supersonic turbulent convection concept and Roche limit and established a limit of 1.442. It is concluded that Kepler's law determines the rotation period of the sun at the time of its formation at the present radius to be equal to 0.1216 d. The correlation between orbital periods of the radii and resonant structure is investigated.

  6. Planetary Protection Constraints For Planetary Exploration and Exobiology

    Science.gov (United States)

    Debus, A.; Bonneville, R.; Viso, M.

    According to the article IX of the OUTER SPACE TREATY (London / Washington January 27., 1967) and in the frame of extraterrestrial missions, it is required to preserve planets and Earth from contamination. For ethical, safety and scientific reasons, the space agencies have to comply with the Outer Space Treaty and to take into account the related planetary protection Cospar recommendations. Planetary protection takes also into account the protection of exobiological science, because the results of life detection experimentations could have impacts on planetary protection regulations. The validation of their results depends strongly of how the samples have been collected, stored and analyzed, and particularly of their biological and organic cleanliness. Any risk of contamination by organic materials, chemical coumpounds and by terrestrial microorganisms must be avoided. A large number of missions is presently scheduled, particularly on Mars, in order to search for life or traces of past life. In the frame of such missions, CNES is building a planetary protection organization in order handle and to take in charge all tasks linked to science and engineering concerned by planetary protection. Taking into account CNES past experience in planetary protection related to the Mars 96 mission, its planned participation in exobiological missions with NASA as well as its works and involvement in Cospar activities, this paper will present the main requirements in order to avoid celestial bodies biological contamination, focussing on Mars and including Earth, and to protect exobiological science.

  7. In Situ Planetary Geochronology Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — This project's purpose was to determine whether a Pulsed Neutron Generator (PNG) could be used in an instrument that could perform in situ age dating of planetary...

  8. The first frost in the Pipe Nebula

    Science.gov (United States)

    Goto, Miwa; Bailey, Jeffrey D.; Hocuk, Seyit; Caselli, Paola; Esplugues, Gisela B.; Cazaux, Stephanie; Spaans, Marco

    2018-02-01

    Context. Spectroscopic studies of ices in nearby star-forming regions indicate that ice mantles form on dust grains in two distinct steps, starting with polar ice formation (H2O rich) and switching to apolar ice (CO rich). Aims: We test how well the picture applies to more diffuse and quiescent clouds where the formation of the first layers of ice mantles can be witnessed. Methods: Medium-resolution near-infrared spectra are obtained toward background field stars behind the Pipe Nebula. Results: The water ice absorption is positively detected at 3.0 μm in seven lines of sight out of 21 sources for which observed spectra are successfully reduced. The peak optical depth of the water ice is significantly lower than those in Taurus with the same AV. The source with the highest water-ice optical depth shows CO ice absorption at 4.7 μm as well. The fractional abundance of CO ice with respect to water ice is 16-6+7%, and about half as much as the values typically seen in low-mass star-forming regions. Conclusions: A small fractional abundance of CO ice is consistent with some of the existing simulations. Observations of CO2 ice in the early diffuse phase of a cloud play a decisive role in understanding the switching mechanism between polar and apolar ice formation. Based on data collected by SpeX at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration.Based also on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.The final reduced spectra (FITS format) are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610

  9. Abundant Solar Nebula Solids in Comets

    Science.gov (United States)

    Messenger, S.; Keller, L. P.; Nakamura-Messenger, K.; Nguyen, A. N.; Clemett, S.

    2016-01-01

    Comets have been proposed to consist of unprocessed interstellar materials together with a variable amount of thermally annealed interstellar grains. Recent studies of cometary solids in the laboratory have shown that comets instead consist of a wide range of materials from across the protoplanetary disk, in addition to a minor complement of interstellar materials. These advances were made possible by the return of direct samples of comet 81P/Wild 2 coma dust by the NASA Stardust mission and recent advances in microscale analytical techniques. Isotopic studies of 'cometary' chondritic porous interplanetary dust particles (CP-IDPs) and comet 81P/Wild 2 Stardust samples show that preserved interstellar materials are more abundant in comets than in any class of meteorite. Identified interstellar materials include sub-micron-sized presolar silicates, oxides, and SiC dust grains and some fraction of the organic material that binds the samples together. Presolar grain abundances reach 1 weight percentage in the most stardust-rich CP-IDPs, 50 times greater than in meteorites. Yet, order of magnitude variations in presolar grain abundances among CP-IDPs suggest cometary solids experienced significant variations in the degree of processing in the solar nebula. Comets contain a surprisingly high abundance of nebular solids formed or altered at high temperatures. Comet 81P/Wild 2 samples include 10-40 micron-sized, refractory Ca- Al-rich inclusion (CAI)-, chondrule-, and ameboid olivine aggregate (AOA)-like materials. The O isotopic compositions of these refractory materials are remarkably similar to their meteoritic counterparts, ranging from 5 percent enrichments in (sup 16) O to near-terrestrial values. Comet 81P/Wild 2 and CP-IDPs also contain abundant Mg-Fe crystalline and amorphous silicates whose O isotopic compositions are also consistent with Solar System origins. Unlike meteorites, that are dominated by locally-produced materials, comets appear to be composed of

  10. N IV emission lines in the ultraviolet spectra of gaseous nebulae

    Science.gov (United States)

    Keenan, F. P.; Ramsbottom, C. A.; Bell, K. L.; Berrington, K. A.; Hibbert, A.; Feibelman, W. A.; Blair, W. P.

    1995-01-01

    Theoretical electron density sensitive emission-line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R = I(2s(sup 2) (1)S-2s2p 3P(sub 2))/I(2s(sup 2) (1)S-2s2p 3P(sub 1) = 1(1483 A)/I(1486 A) in N IV. These are found to be up to an order of magnitude different from those deduced by previous authors, principally due to the inclusion of excitation rates for transitions among the 2s2p (3)p fine-structure levels. The observed values of R for several planetary nebulae, symbiotic stars and the Cygnus Loop supernova remnant, measured from spectra obtained with the International Ultraviolet Explorer (IUE) satellite and the Hopkins Ultraviolet Explorer (HUT), lead to electron densities which are in excellent agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations.

  11. Formation of a hybrid-type proto-atmosphere on Mars accreting in the solar nebula

    Science.gov (United States)

    Saito, Hiroaki; Kuramoto, Kiyoshi

    2018-03-01

    Recent studies of the chronology of Martian meteorites suggest that the growth of Mars was almost complete within a few Myr after the birth of the Solar system. During such rapid accretion, proto-Mars likely gravitationally maintained both the solar nebula component and the impact degassing component, containing H2O vapour and reduced gas species, as a proto-atmosphere to be called a hybrid-type proto-atmosphere. Here we numerically analyse the mass and composition of the degassed component and the atmospheric thermal structure sustained by accretional heating. Our results predict that a growing Mars possibly acquired a massive and hot hybrid-type proto-atmosphere with surface pressure and temperature greater than several kbar and 2000 K, respectively, which is sufficient to produce a deep magma ocean. In such a high-temperature and high-pressure environment, a significant amount of H2O, CH4, CO, and H2 is expected to be partitioned into the planetary interior, although this would strongly depend on the dynamics of the magma ocean and mantle solidification. The dissolved H2O may explain the wet Martian mantle implied from basaltic Martian meteorites. Along with the remnant reduced atmosphere after the hydrodynamic atmospheric escape, dissolved reduced gas species may have maintained an earliest Martian surface environment that allowed prebiotic chemical evolution and liquid H2O activities.

  12. Planetary Geologic Mapping Handbook - 2009

    Science.gov (United States)

    Tanaka, K. L.; Skinner, J. A.; Hare, T. M.

    2009-01-01

    Geologic maps present, in an historical context, fundamental syntheses of interpretations of the materials, landforms, structures, and processes that characterize planetary surfaces and shallow subsurfaces (e.g., Varnes, 1974). Such maps also provide a contextual framework for summarizing and evaluating thematic research for a given region or body. In planetary exploration, for example, geologic maps are used for specialized investigations such as targeting regions of interest for data collection and for characterizing sites for landed missions. Whereas most modern terrestrial geologic maps are constructed from regional views provided by remote sensing data and supplemented in detail by field-based observations and measurements, planetary maps have been largely based on analyses of orbital photography. For planetary bodies in particular, geologic maps commonly represent a snapshot of a surface, because they are based on available information at a time when new data are still being acquired. Thus the field of planetary geologic mapping has been evolving rapidly to embrace the use of new data and modern technology and to accommodate the growing needs of planetary exploration. Planetary geologic maps have been published by the U.S. Geological Survey (USGS) since 1962 (Hackman, 1962). Over this time, numerous maps of several planetary bodies have been prepared at a variety of scales and projections using the best available image and topographic bases. Early geologic map bases commonly consisted of hand-mosaicked photographs or airbrushed shaded-relief views and geologic linework was manually drafted using mylar bases and ink drafting pens. Map publishing required a tedious process of scribing, color peel-coat preparation, typesetting, and photo-laboratory work. Beginning in the 1990s, inexpensive computing, display capability and user-friendly illustration software allowed maps to be drawn using digital tools rather than pen and ink, and mylar bases became obsolete

  13. Protostar Evolution in the Orion Nebula Cluster (ONC)

    Science.gov (United States)

    Sanchez, Michael Allan

    2018-01-01

    We present our preliminary analysis of the protostars within the Orion Nebula Cluster (ONC). We developed a pipeline to identify protostars in the ONC using the IRAC instrument aboard Spitzer. We verified our photometric measurements with the catalog provided by Megeath et al. (2012). We then classified the protostar evolution stages (0/I, Flatt, II, and III) based on their spectral slope.

  14. Warm molecular gas in the M17 SW nebula

    NARCIS (Netherlands)

    Pérez-Beaupuits, J. P.; Spaans, M.; Hogerheijde, M.; Güsten, R.; Corbett, IF

    2010-01-01

    High resolution maps of the (12)CO J = 6 -> 5 line and the [C I] (3) P(2) (3)P(1) (370 mu m) fine-structure transition in the Galactic nebula M17 SW are presented. The maps were obtained using the dual color multiple pixel receiver CHAMP(+) on the APEX dagger telescope.

  15. FORMING CHONDRITES IN A SOLAR NEBULA WITH MAGNETICALLY INDUCED TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi, E-mail: yasuhiro@caltech.edu [Center for Computational Astrophysics, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-03-20

    Chondritic meteorites provide valuable opportunities to investigate the origins of the solar system. We explore impact jetting as a mechanism of chondrule formation and subsequent pebble accretion as a mechanism of accreting chondrules onto parent bodies of chondrites, and investigate how these two processes can account for the currently available meteoritic data. We find that when the solar nebula is ≤5 times more massive than the minimum-mass solar nebula at a ≃ 2–3 au and parent bodies of chondrites are ≤10{sup 24} g (≤500 km in radius) in the solar nebula, impact jetting and subsequent pebble accretion can reproduce a number of properties of the meteoritic data. The properties include the present asteroid belt mass, the formation timescale of chondrules, and the magnetic field strength of the nebula derived from chondrules in Semarkona. Since this scenario requires a first generation of planetesimals that trigger impact jetting and serve as parent bodies to accrete chondrules, the upper limit of parent bodies’ masses leads to the following implications: primordial asteroids that were originally ≥10{sup 24} g in mass were unlikely to contain chondrules, while less massive primordial asteroids likely had a chondrule-rich surface layer. The scenario developed from impact jetting and pebble accretion can therefore provide new insights into the origins of the solar system.

  16. Multibaseline Observations of the Occultation of Crab Nebula by the ...

    Indian Academy of Sciences (India)

    tribpo

    Observations of the radio source Crab Nebula were made at the time of transit during. June 1986 and 1987. The fringe amplitude V(S) for a baseline S was calibrated using the corresponding baseline fringe amplitude of radio source 3C123 or 3C134 and normalised to the preoccultation value V(O). Normalised fringe ...

  17. An Analysis of Spectra in the Red Rectangle Nebula

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Only the reddest part of the spectra can safely be attributed to light from the nebula, and indicates Rayleigh scattering by the gas, in conformity with the large angles of scattering involved and the proximity of the star. In the blue, light from HD 44179, refracted or scattered in the atmosphere, dominates the ...

  18. Hard X-ray Variations in the Crab Nebula

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Cherry, M. L.; Case, G. L.; Baumgartner, W. H.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Camero-Arranz, A.; Connaughton, V.; Finger, M. H.; hide

    2013-01-01

    In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM), August 2008 to August 2010, approximately 7% (70 mcrab) decline was discovered in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline was independently confirmed with four other instruments: the RXTE/PCA, Swift/BAT, INTEGRAL/IBIS, and INTEGRAL/SPI. The pulsed flux measured with RXTE/PCA from 1999-2010 was consistent with the pulsar spin-down, indicating that the observed changes were nebular. From 2001 to 2010, the Crab nebula flux measured with RXTE/ PCA was particularly variable, changing by up to approximately 3.5% per year in the 15-50 keV band. These variations were confirmed with INTEGRAL/SPI starting in 2003, Swift/BAT starting in 2005, and Fermi GBM starting in 2008. Before 2001 and since 2010, the Crab nebula flux has appeared more stable, varying by less than 2% per year. I will present updated light curves in multiple energy bands for the Crab Nebula, including recent data from Fermi GBM, Swift/BAT, INTEGRAL and MAXI, and a 16-year long light curve from RXTE/PCA.

  19. Crab Nebula Variations in Hard X-rays

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2012-01-01

    The Crab Nebula was surprisingly variable from 2001-2010, with less variability before 2001 and since mid-2010. We presented evidence for spectral softening from RXTE, Swift/BAT, and Fermi GBM during the mid-2008-2010 flux decline. We see no clear connections between the hard X-ray variations and the GeV flares

  20. Preferrential Concentration of Particles in Protoplanetary Nebula Turbulence

    Science.gov (United States)

    Hartlep, Thomas; Cuzzi, Jeffrey N.

    2015-01-01

    Preferential concentration in turbulence is a process that causes inertial particles to cluster in regions of high strain (in-between high vorticity regions), with specifics depending on their stopping time or Stokes number. This process is thought to be of importance in various problems including cloud droplet formation and aerosol transport in the atmosphere, sprays, and also in the formation of asteroids and comets in protoplanetary nebulae. In protoplanetary nebulae, the initial accretion of primitive bodies from freely-floating particles remains a problematic subject. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" [1] in turbulent nebulae. One scenario that can lead directly from independent nebula particulates to large objects, avoiding the problematic m-km size range, involves formation of dense clumps of aerodynamically selected, typically mm-size particles in protoplanetary turbulence. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles generally known as "chondrules" [2]. Thus, while it is arcane, turbulent preferential concentration acting directly on chondrule size particles are worthy of deeper study. Here, we present the statistical determination of particle multiplier distributions from numerical simulations of particle-laden isotopic turbulence, and a cascade model for modeling turbulent concentration at lengthscales and Reynolds numbers not accessible by numerical simulations. We find that the multiplier distributions are scale dependent at the very largest scales but have scale-invariant properties under a particular variable normalization at smaller scales.

  1. Millimeter-wave molecular line observations of the Tornado nebula

    International Nuclear Information System (INIS)

    Sakai, D.; Oka, T.; Tanaka, K.; Matsumura, S.; Miura, K.; Takekawa, S.

    2014-01-01

    We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7-0.1), which is a bright radio source behind the Galactic center region. A 15' × 15' area was mapped in the J = 1-0 lines of CO, 13 CO, and HCO + with the Nobeyama Radio Observatory 45 m telescope. The Very Large Array archival data of OH at 1720 MHz were also reanalyzed. We found two molecular clouds with separate velocities, V LSR = –14 km s –1 and +5 km s –1 . These clouds show rough spatial anti-correlation. Both clouds are associated with OH 1720 MHz emissions in the area overlapping with the Tornado Nebula. The spatial and velocity coincidence indicates violent interaction between the clouds and the Tornado Nebula. Modestly excited gas prefers the position of the Tornado 'head' in the –14 km s –1 cloud, also suggesting the interaction. Virial analysis shows that the +5 km s –1 cloud is more tightly bound by self-gravity than the –14 km s –1 cloud. We propose a formation scenario for the Tornado Nebula; the +5 km s –1 cloud collided into the –14 km s –1 cloud, generating a high-density layer behind the shock front, which activates a putative compact object by Bondi-Hoyle-Lyttleton accretion to eject a pair of bipolar jets.

  2. A 100 kpc nebula associated with the `Teacup' fading quasar

    Science.gov (United States)

    Villar-Martín, M.; Cabrera-Lavers, A.; Humphrey, A.; Silva, M.; Ramos Almeida, C.; Piqueras-López, J.; Emonts, B.

    2018-02-01

    We report the discovery of an ˜100 kpc ionized nebula associated with the radio-quiet type 2 quasar (QSO2) nicknamed the `Teacup' (z = 0.085). The giant nebula is among the largest known around active galaxies at any z. We propose that it is part of the circumgalactic medium (CGM) of the QSO2 host, which has been populated with tidal debris by galactic interactions. This rich gaseous medium has been rendered visible due to the illumination by the powerful active nucleus (AGN). Subsolar abundances (˜0.5 Z⊙) are tentatively favoured by AGN photoionization models. We also report the detection of coronal emission (Fe+6) from the NE bubble, at ˜9 kpc from the AGN. The detection of coronal lines at such large distances from the AGN and the [N II] λ6583/Hα, [S II] λλ6716,6731/Hα, [O I] λ6300/Hα optical emission-line ratios of the giant nebula are consistent with the fading quasar scenario proposed by Gagne et al. The fading rate appears to have been faster in the last ˜46 000 yr. Deep wide field integral field spectroscopy of giant nebulae around powerful AGN such as the `Teacup's' with instruments such as MUSE on VLT opens up a way to detect and study the elusive material from the CGM around massive active galaxies thanks to the illumination by the luminous AGN.

  3. NASA Planetary Visualization Tool

    Science.gov (United States)

    Hogan, P.; Kim, R.

    2004-12-01

    NASA World Wind allows one to zoom from satellite altitude into any place on Earth, leveraging the combination of high resolution LandSat imagery and SRTM elevation data to experience Earth in visually rich 3D, just as if they were really there. NASA World Wind combines LandSat 7 imagery with Shuttle Radar Topography Mission (SRTM) elevation data, for a dramatic view of the Earth at eye level. Users can literally fly across the world's terrain from any location in any direction. Particular focus was put into the ease of usability so people of all ages can enjoy World Wind. All one needs to control World Wind is a two button mouse. Additional guides and features can be accessed though a simplified menu. Navigation is automated with single clicks of a mouse as well as the ability to type in any location and automatically zoom to it. NASA World Wind was designed to run on recent PC hardware with the same technology used by today's 3D video games. NASA World Wind delivers the NASA Blue Marble, spectacular true-color imagery of the entire Earth at 1-kilometer-per-pixel. Using NASA World Wind, you can continue to zoom past Blue Marble resolution to seamlessly experience the extremely detailed mosaic of LandSat 7 data at an impressive 15-meters-per-pixel resolution. NASA World Wind also delivers other color bands such as the infrared spectrum. The NASA Scientific Visualization Studio at Goddard Space Flight Center (GSFC) has produced a set of visually intense animations that demonstrate a variety of subjects such as hurricane dynamics and seasonal changes across the globe. NASA World Wind takes these animations and plays them directly on the world. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) produces a set of time relevant planetary imagery that's updated every day. MODIS catalogs fires, floods, dust, smoke, storms and volcanic activity. NASA World Wind produces an easily customized view of this information and marks them directly on the globe. When one

  4. Polymer light emitting diodes

    International Nuclear Information System (INIS)

    Gautier-Thianche, Emmmanuelle

    1998-01-01

    We study sandwich type semiconducting polymer light emitting diodes; anode/polymer/cathode. ITO is selected as anode, this polymer is a blend of a commercially available polymer with a high hole transport ability: polyvinyl-carbazole and a laser dye: coumarin-515. Magnesium covered with silver is chosen for the anode. We study the influence of polymer thickness and coumarin doping ratio on electroluminescence spectrum, electric characteristics and quantum efficiency. An important drawback is that diodes lifetime remains low. In the second part of our study we determine degradations causes with X-Ray reflectivity experiments. It may be due to ITO very high roughness. We realize a new type of planar electroluminescent device: a channel type electroluminescent device in which polymer layer is inserted into an aluminium channel. Such a device is by far more stable than using classical sandwich structures with the same polymer composition: indeed, charges are generated by internal-field ionization and there is no injection from the electrode to the polymer. This avoids electrochemical reactions at electrodes, thus reducing degradations routes. (author) [fr

  5. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  6. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  7. The OpenPlanetary initiative

    Science.gov (United States)

    Manaud, Nicolas; Rossi, Angelo Pio; Hare, Trent; Aye, Michael; Galluzzi, Valentina; van Gasselt, Stephan; Martinez, Santa; McAuliffe, Jonathan; Million, Chase; Nass, Andrea; Zinzi, Angelo

    2016-10-01

    "Open" has become attached to several concepts: science, data, and software are some of the most obvious. It is already common practice within the planetary science community to share spacecraft missions data freely and openly [1]. However, this is not historically the case for software tools, source code, and derived data sets, which are often reproduced independently by multiple individuals and groups. Sharing data, tools and overall knowledge would increase scientific return and benefits [e.g. 2], and recent projects and initiatives are helping toward this goal [e.g. 3,4,5,6].OpenPlanetary is a bottom-up initiative to address the need of the planetary science community for sharing ideas and collaborating on common planetary research and data analysis problems, new challenges, and opportunities. It started from an initial participants effort to stay connected and share information related to and beyond the ESA's first Planetary GIS Workshop [7]. It then continued during the 2nd (US) Planetary Data Workshop [8], and aggregated more people.Our objective is to build an online distributed framework enabling open collaborations within the planetary science community. We aim to co-create, curate and publish resource materials and data sets; to organise online events, to support community-based projects development; and to offer a real-time communication channel at and between conferences and workshops.We will present our current framework and resources, developing projects and ideas, and solicit for feedback and participation. OpenPlanetary is intended for research and education professionals: scientists, engineers, designers, teachers and students, as well as the general public that includes enthusiasts and citizen scientists. All are welcome to join and contribute at openplanetary.co[1] International Planetary Data Alliance, planetarydata.org. [2] Nosek et al (2015), dx.doi.org/10.1126/science.aab2374. [3] Erard S. et al. (2016), EGU2016-17527. [4] Proposal for a PDS

  8. Planetary Transmission Diagnostics

    Science.gov (United States)

    Lewicki, David G. (Technical Monitor); Samuel, Paul D.; Conroy, Joseph K.; Pines, Darryll J.

    2004-01-01

    This report presents a methodology for detecting and diagnosing gear faults in the planetary stage of a helicopter transmission. This diagnostic technique is based on the constrained adaptive lifting algorithm. The lifting scheme, developed by Wim Sweldens of Bell Labs, is a time domain, prediction-error realization of the wavelet transform that allows for greater flexibility in the construction of wavelet bases. Classic lifting analyzes a given signal using wavelets derived from a single fundamental basis function. A number of researchers have proposed techniques for adding adaptivity to the lifting scheme, allowing the transform to choose from a set of fundamental bases the basis that best fits the signal. This characteristic is desirable for gear diagnostics as it allows the technique to tailor itself to a specific transmission by selecting a set of wavelets that best represent vibration signals obtained while the gearbox is operating under healthy-state conditions. However, constraints on certain basis characteristics are necessary to enhance the detection of local wave-form changes caused by certain types of gear damage. The proposed methodology analyzes individual tooth-mesh waveforms from a healthy-state gearbox vibration signal that was generated using the vibration separation (synchronous signal-averaging) algorithm. Each waveform is separated into analysis domains using zeros of its slope and curvature. The bases selected in each analysis domain are chosen to minimize the prediction error, and constrained to have the same-sign local slope and curvature as the original signal. The resulting set of bases is used to analyze future-state vibration signals and the lifting prediction error is inspected. The constraints allow the transform to effectively adapt to global amplitude changes, yielding small prediction errors. However, local wave-form changes associated with certain types of gear damage are poorly adapted, causing a significant change in the

  9. Planetary Geophysics and Tectonics

    Science.gov (United States)

    Zuber, Maria

    2005-01-01

    The broad objective of this work is to improve understanding of the internal structures and thermal and stress histories of the solid planets by combining results from analytical and computational modeling, and geophysical data analysis of gravity, topography and tectonic surface structures. During the past year we performed two quite independent studies in the attempt to explain the Mariner 10 magnetic observations of Mercury. In the first we revisited the possibility of crustal remanence by studying the conditions under which one could break symmetry inherent in Runcorn's model of a uniformly magnetized shell to produce a remanent signal with a dipolar form. In the second we applied a thin shell dynamo model to evaluate the range of intensity/structure for which such a planetary configuration can produce a dipole field consistent with Mariner 10 results. In the next full proposal cycle we will: (1) develop numerical and analytical and models of thin shell dynamos to address the possible nature of Mercury s present-day magnetic field and the demise of Mars magnetic field; (2) study the effect of degree-1 mantle convection on a core dynamo as relevant to the early magnetic field of Mars; (3) develop models of how the deep mantles of terrestrial planets are perturbed by large impacts and address the consequences for mantle evolution; (4) study the structure, compensation, state of stress, and viscous relaxation of lunar basins, and address implications for the Moon s state of stress and thermal history by modeling and gravity/topography analysis; and (5) use a three-dimensional viscous relaxation model for a planet with generalized vertical viscosity distribution to study the degree-two components of the Moon's topography and gravity fields to constrain the primordial stress state and spatial heterogeneity of the crust and mantle.

  10. Studies of dust grain properties in infrared reflection nebulae.

    Science.gov (United States)

    Pendleton, Y J; Tielens, A G; Werner, M W

    1990-01-20

    We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light.

  11. Planetary Image Geometry Library

    Science.gov (United States)

    Deen, Robert C.; Pariser, Oleg

    2010-01-01

    The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A

  12. The fragility of planetary systems

    Science.gov (United States)

    Portegies Zwart, S. F.; Jílková, Lucie

    2015-07-01

    We specify the range to which perturbations penetrate a planetesimal system. Such perturbations can originate from massive planets or from encounters with other stars. The latter can have an origin in the star cluster in which the planetary system was born, or from random encounters once the planetary system has escaped its parental cluster. The probability of a random encounter, either in a star cluster or in the Galactic field depends on the local stellar density, the velocity dispersion and the time spend in that environment. By adopting order of magnitude estimates, we argue that the majority of planetary systems born in open clusters will have a Parking zone, in which planetesimals are affected by encounters in their parental star cluster but remain unperturbed after the star has left the cluster. Objects found in this range of semimajor axis and eccentricity preserve the memory of the encounter that last affected their orbits, and they can therefore be used to reconstruct this encounter. Planetary systems born in a denser environment, such as in a globular cluster are unlikely to have a Parking zone. We further argue that some planetary systems may have a Frozen zone, in which orbits are not affected either by the more inner massive planets or by external influences. Objects discovered in this zone will have preserved information about their formation in their orbital parameters.

  13. VARIATIONAL PRINCIPLE FOR PLANETARY INTERIORS

    International Nuclear Information System (INIS)

    Zeng, Li; Jacobsen, Stein B.

    2016-01-01

    In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equations into one, which provides us some insight into the problem. From this principle, a universal mass–radius relation, an estimate of the error propagation from the equation of state to the mass–radius relation, and a form of the virial theorem applicable to planetary interiors are derived.

  14. From Planetary Mapping to Map Production: Planetary Cartography as integral discipline in Planetary Sciences

    Science.gov (United States)

    Nass, Andrea; van Gasselt, Stephan; Hargitai, Hendrik; Hare, Trent; Manaud, Nicolas; Karachevtseva, Irina; Kersten, Elke; Roatsch, Thomas; Wählisch, Marita; Kereszturi, Akos

    2016-04-01

    Cartography is one of the most important communication channels between users of spatial information and laymen as well as the open public alike. This applies to all known real-world objects located either here on Earth or on any other object in our Solar System. In planetary sciences, however, the main use of cartography resides in a concept called planetary mapping with all its various attached meanings: it can be (1) systematic spacecraft observation from orbit, i.e. the retrieval of physical information, (2) the interpretation of discrete planetary surface units and their abstraction, or it can be (3) planetary cartography sensu strictu, i.e., the technical and artistic creation of map products. As the concept of planetary mapping covers a wide range of different information and knowledge levels, aims associated with the concept of mapping consequently range from a technical and engineering focus to a scientific distillation process. Among others, scientific centers focusing on planetary cartography are the United State Geological Survey (USGS, Flagstaff), the Moscow State University of Geodesy and Cartography (MIIGAiK, Moscow), Eötvös Loránd University (ELTE, Hungary), and the German Aerospace Center (DLR, Berlin). The International Astronomical Union (IAU), the Commission Planetary Cartography within International Cartographic Association (ICA), the Open Geospatial Consortium (OGC), the WG IV/8 Planetary Mapping and Spatial Databases within International Society for Photogrammetry and Remote Sensing (ISPRS) and a range of other institutions contribute on definition frameworks in planetary cartography. Classical cartography is nowadays often (mis-)understood as a tool mainly rather than a scientific discipline and an art of communication. Consequently, concepts of information systems, mapping tools and cartographic frameworks are used interchangeably, and cartographic workflows and visualization of spatial information in thematic maps have often been

  15. Hydrocarbons on Saturns Satellites: Relationship to Interstellar Dust and the Solar Nebula

    Science.gov (United States)

    Cruikshank, D. P.

    2012-01-01

    To understand the origin and evolution of our Solar System, and the basic components that led to life on Earth, we study interstellar and planetary spectroscopic signatures. The possible relationship of organic material detected in carbonaceous meteorites, interplanetary dust particles (IDPs), comets and the interstellar medium have been the source of speculation over the years as the composition and processes that governed the early solar nebula have been explored to understand the extent to which primitive material survived or became processed. The Cassini VIMS has provided new data relevant to this problem. Three of Saturn's satellites, Phoebe, Iapetus, and Hyperion, are found to have aromatic and aliphatic hydrocarbons on their surfaces. The aromatic hydrocarbon signature (C-H stretching mode at 3.28 micrometers) is proportionally significantly stronger (relative to the aliphatic bands) than that seen in other Solar System bodies (e.g., comets) and materials (Stardust samples, IDPs, meteorites) and the distinctive sub-features of the 3.4 micrometer aliphatic band (CH2 and CH3 groups) are reminiscent of those widely detected throughout the diffuse ISM. Phoebe may be a captured object that originated in the region beyond the present orbit of Neptune, where the solar nebula contained a large fraction of original interstellar ice and dust that was less processed than material closer to the Sun. Debris from Phoebe now resident on Iapetus and Hyperion, as well as o Phoebe itself, thus presents a unique blend of hydrocarbons, amenable to comparisons with interstellar hydrocarbons and other Solar System materials. The dust ring surrounding Saturn, in which Phoebe is embedded, probably originated from a collision with Phoebe. Dust ring particles are the likely source of the organic-bearing materials, and perhaps the recently identified small particles of Fe detected on Saturn's satellites. Lab measurements of the absolute band strengths of representative aliphatic and

  16. Timing of Solar Nebula Dispersal Constrained by Early Solar System Paleomagnetism

    Science.gov (United States)

    Wang, H.; Weiss, B. P.; Downey, B. G.; Bai, X. N.; Wang, J.; Suavet, C. R.; Fu, R. R.; Lima, E. A.; Zucolotto, M. E.

    2015-12-01

    The formation of the solar system/extrasolar planets largely takes place in the gas-rich solar nebular/protoplanetary disks. Nebular magnetic fields are thought to play a dominant role in global disk evolution by driving angular momentum transport via the magneto-rotational instability and/or magnetized disk winds, with the magnetically-driven accretion rate proportional to the square of the field strength. Previous paleomagnetic analyses of the Semarkona meteorite found evidence for a ~5-50 μT solar nebular field at ~2-3 My after the formation of calcium-aluminum-rich inclusions (CAIs), which consist of the first solids condensed from the cooling protoplanetary disk. These field strengths are consistent with stellar accretion rates of ~10-8 Msun/yr as typically observed for Sun-like stars. A key remaining question is the time when the nebular magnetic field and solar nebula itself dispersed. To address this, we analyzed the paleomagnetism of angrites, a class of exceptionally well-preserved igneous rocks that should retain magnetic records beginning just ~4 My after CAI formation. Here we present paleomagnetic, rock magnetic, and synchrotron-based transmission X-ray microscopic analyses of the quenched angrites D'Orbigny, Sahara 99555 and Asuka 881371. Our data show that the magnetic field at the angrite parent body region was < ~0.1 µT at ~4 My after CAI formation. This indicates that the nebular magnetic field had rapidly declined by at least a factor of ~50 by that time, such that the magnetically driven solar accretion rate was well below 10-11 Msun/yr. Because a strong nebular magnetic field was likely present throughout most of the gaseous disk lifetime, our results suggest that the solar nebula itself had probably already dispersed by ~4 My after CAI formation. This dispersal time agrees with typical protoplanetary disk lifetimes inferred from infrared excesses for Sun-like protostars. Our results suggest that the formation of the solar system giant

  17. The jovian nebula: a post-voyager perspective.

    Science.gov (United States)

    Trauger, J T

    1984-10-19

    Voyager 1 carried a diverse collection of magnetospheric probes through the inner Jovian magnetosphere in March 1979. The ensuing data analysis and theoretical investigation provided a comprehensive description of the Jovian nebula, a luminous torus populated with newly released heavy ions drawn from Io's surface. Recent refinements in Earth-based imaging instrumentation are used to extend the Voyager in situ picture in temporal and spatial coverage. An analysis of [SIII] and [SII] optical emissions observed during the Jovian apparitions of 1981 through 1983 reveals three distinct torus components. Regularities have been identified in the ion partitioning and ion densities in the hot outer and inner tori, sharply defined radial structure is found in the plasma near Io, and the relative permanence of the cool inner torus is inferred. An extended cloud of neutral material is required as a source of fresh ions in the nebula.

  18. Catalysis by Dust Grains in the Solar Nebula

    Science.gov (United States)

    Kress, Monika E.; Tielens, Alexander G. G. M.

    1996-01-01

    In order to determine whether grain-catalyzed reactions played an important role in the chemistry of the solar nebula, we have applied our time-dependent model of methane formation via Fischer-Tropsch catalysis to pressures from 10(exp -5) to 1 bar and temperatures from 450 to 650 K. Under these physical conditions, the reaction 3H2 + CO yields CH4 + H2O is readily catalyzed by an iron or nickel surface, whereas the same reaction is kinetically inhibited in the gas phase. Our model results indicate that under certain nebular conditions, conversion of CO to methane could be extremely efficient in the presence of iron-nickel dust grains over timescales very short compared to the lifetime of the solar nebula.

  19. Al-Sufi's Investigation of Stars, Star Clusters and Nebulae

    Science.gov (United States)

    Hafez, Ihsan; Stephenson, F. R.; Orchiston, W.

    2011-01-01

    The distinguished Arabic astronomer, Al-Sufi (AD 903-986) is justly famous for his Book of the Fixed Stars, an outstanding Medieval treatise on astronomy that was assembled in 964. Developed from Ptolemy's Algamest, but based upon al-Sufi's own stellar observations, the Book of the Fixed Stars has been copied down through the ages, and currently 35 copies are known to exist in various archival repositories around the world. Among other things, this major work contains 55 astronomical tables, plus star charts for 48 constellations. For the first time a long-overdue English translation of this important early work is in active preparation. In this paper we provide biographical material about Al-Sufi and the contents of his Book of the Fixed Stars, before examining his novel stellar magnitude system, and his listing of star clusters and nebulae (including the first-ever mention of the Great Nebula in Andromeda).

  20. SPEX: The spectropolarimeter for planetary EXploration

    NARCIS (Netherlands)

    Snik, F.; Rietjens, J.H.H.; Harten, G. van; Stam, D.M.; Keller, C.U.; Smit, J.M.; Laan, E.C.; Verlaan, A.L.; Horst, R. ter; Navarro, R.; Wielinga, K.; Moon, S.G.; Voors, R.

    2010-01-01

    SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact instrument for spectropolarimetry, and in particular for detecting and characterizing aerosols in planetary atmospheres. With its ∼1-liter volume it is capable of full linear spectropolarimetry, without moving parts. The

  1. The FU Orionis Phenomenon and Solar Nebula Material

    Science.gov (United States)

    Bell, K. R.; Cassen, P. M.; Wasson, J. T.; Woolum, D. S.

    2001-01-01

    We summarize astronomical, meteoritic, and theoretical evidence relating to the FU Orionis phenomenon. This evidence suggests that at early times (the first few 10(exp 5) yr), the solar nebula experienced a hot phase characterized by high accretion rates (the "FU Ori epoch"), punctuated by episodic outbursts of enhanced mass flow through the inner part of the disk (less than or equal to 0.3 AU). Throughout this epoch, disk midplane temperatures exceeded 1000 K at 1 AU. Diminishing infall from the cloud core led to decreasing mass flux throughout the disk. When mass flow de creased below the value critical for outburst (5 x 10(exp -7) solar mass/yr, as suggested by thermal ionization instability models), outbursts ceased and the T Tauri epoch began. Outburst timescales are too long to explain calcium- and aluminum-rich inclusion (CAI) and chondrule formation. Volatility-dependent fractionation patterns seen in meteoritic materials suggest that solids formed beginning during a hot epoch when temperatures exceeded 1400 K, and the presence of volatiles in chondrites argues that this process continued until the nebula had cooled to below 400 K. The thermal ionization instability model for FU Ori outbursts is in quantitative agreement with astronomical observations. Its results imply that the terrestrial region of the nebula reached the hot end of this range only during a time when mass flow through the disk was high enough to trigger outbursts (i.e., the FU Ori epoch) and reached the cool end of this range only during the later T Tauri epoch. According to the models, heating of material in the terrestrial planet region during individual FU Ori outbursts would be limited to surface layers of the nebula, leaving midplane materials (which are at greater than or equal to 1000 K) largely unaffected. Alternative FU Ori models should be developed, particularly if compositional differences among chondrite clans are attributable to episodic heating.

  2. Hydrodynamics of photoionized columns in the Eagle Nebula, M 16

    OpenAIRE

    Williams, R. J. R.; Ward-Thompson, D.; Whitworth, A. P.

    2001-01-01

    We present hydrodynamical simulations of the formation, structure and evolution of photoionized columns, with parameters based on those observed in the Eagle Nebula. On the basis of these simulations we argue that there is no unequivocal evidence that the dense neutral clumps at heads of the columns were cores in the pre-existing molecular cloud. In our simulations, a variety of initial conditions leads to the formation and maintenance of near-equilibrium columns. Therefore, it is likely that...

  3. Two phases of the interstellar medium in nebulas around quasars

    Energy Technology Data Exchange (ETDEWEB)

    Zentsova, A.S.

    1988-05-01

    It is shown that for the interstellar gas in nebulas surrounding quasars the condition of thermal instability is satisfied, and the gas must separate into two phases: cold (T /approx equal/ 10/sup 4//degree/K) dense clouds and a hot (T /approx equal/ 10/sup 8//degree/K) rarefied medium. The density, size, and mass of the clouds formed by the development of the thermal instability are estimated.

  4. A BROADBAND EMISSION MODEL OF MAGNETAR WIND NEBULAE

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Shuta J. [Department of Physics, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Kobe, Hyogo 658-8501 (Japan)

    2016-08-20

    Angular momentum loss by the plasma wind is considered as a universal feature of isolated neutron stars including magnetars. The wind nebulae that are powered by magnetars allow us to compare the wind properties and the spin evolution of magnetars with those of rotation-powered pulsars (RPPs). In this paper, we construct a broadband emission model of magnetar wind nebulae (MWNe). This model is similar to past studies of young pulsar wind nebulae (PWNe) around RPPs, but is modified for the application to MWNe that have far less observational information than the young PWNe. We apply the model to the MWN around the youngest (∼1 kyr) magnetar, 1E 1547.0-5408, which has the largest spin-down power L {sub spin} among all the magnetars. However, the MWN is faint because of the low L {sub spin} of 1E 1547.0-5408 when compared to the young RPPs. Since most parameters are not well constrained by only an X-ray flux upper limit of the MWN, we adopt the model’s parameters from the young PWN Kes 75 around PSR J1846-0258, which is a peculiar RPP showing magnetar-like behaviors. The model predicts that γ -ray flux will be detected in a future TeV γ -ray observation by CTA (Cherenkov Telescope Array). The MWN spectrum does not allow us to test the hypothesis that 1E 1547.0-5408 had a period of milliseconds at its birth because the particles injected during the early phase of evolution suffered from severe adiabatic and synchrotron losses. Furthermore, both observational and theoretical studies of the wind nebulae around magnetars are required to constrain the wind and the spin-down properties of magnetars.

  5. GTR Component of Planetary Precession

    Indian Academy of Sciences (India)

    detection of gravitational waves has only augmented their en- thusiasm about the General Theory of Relativity ... the GTR advance of the perihelion of planetary motion about the sun. 1. Introduction. When you throw an ... cury's orbit was estimated to advance by about 565 seconds of an arc per Earth-century. It is also now ...

  6. CO survey of the dark nebulae in Taurus and Perseus

    International Nuclear Information System (INIS)

    Baran, G.P.

    1986-01-01

    The thesis reports a large-scale survey of carbon monoxide ( 12 CO) emission (at λ = 2.6 mm) from dark nebulae in Taurus and Perseus. CO spectra at 4395 points were obtained within an area of about 800 square degrees generally west of the galactic anti-center. The spatial resolution of the instrument was eight arcminutes and velocity resolution was 2.6 km s -1 /. CO emission is strongest wherever extinction by dust is greatest, spilling over the apparent outer boundaries of the dust clouds observed optically. Combining CO velocity for the nebulae with optically determined distances shows that the clouds in the survey area form several layers. The molecular cloud mass closest to the sun is the Taurus and Auriga complex about 150 +/- 50 pc). Nearer to the Per )B2 OB association (at 350 +/- 100 pc) than the Taurus clouds are the Per OB2 molecular cloud (350 +/- 100 pc) and the California Nebula = NGC15979 molecular clouds (at 400 +/- 150 pc). Cloud masses were determined from integrated CO emission intensity alone by assuming that γ-ray emission intensities can be used to relate H 2 column densities to CO emission intensities

  7. Planetary imaging with amateur astronomical instruments

    Science.gov (United States)

    Papathanasopoulos, k.; Giannaris, G.

    2017-09-01

    Planetary imaging can be varied by the types and size of instruments and processing. With basic amateur telescopes and software, can be captured images of our planetary system, mainly Jupiter, Saturn and Mars, but also solar eclipses, solar flares, and many more. Planetary photos can be useful for professional astronomers, and how amateur astronomers can play a role on that field.

  8. Physical Properties of the Very Young PN Hen3-1357 (Stingray Nebula) Based on Multiwavelength Observations

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Masaaki [Institute of Astronomy and Astrophysics Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU. No.1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C. (China); Parthasarathy, M. [Indian Institute of Astrophysics, II B lock Koramangala, Bangalore 560034, Karnataka (India); Tajitsu, A. [Subaru Telescope, National Astronomical Observatory of Japan, 650 N Aohoku Place, Hilo, HI 96720 (United States); Hubrig, S., E-mail: otsuka@asiaa.sinica.edu.tw [Leibniz-Institut fuer Astrophysik Potsdam (AIP) An der Sternwarte 12, D-14482 Potsdam (Germany)

    2017-03-20

    We carried out a detailed analysis of the interesting and important very young planetary nebula (PN) Hen3-1357 (Stingray Nebula) based on a unique data set of optical to far-IR spectra and photometric images. We calculated the abundances of nine elements using collisionally excited lines (CELs) and recombination lines (RLs). The RL C/O ratio indicates that this PN is O-rich, which is also supported by the detection of the broad 9/18 μ m bands from amorphous silicate grains. The observed elemental abundances can be explained by asymptotic giant branch (AGB) nucleosynthesis models for initially 1–1.5 M {sub ⊙} stars with Z = 0.008. The Ne overabundance might be due to the enhancement of {sup 22}Ne isotope in the He-rich intershell. Using the spectrum of the central star synthesized by Tlusty as the ionization/heating source of the PN, we constructed the self-consistent photoionization model with Cloudy to the observed quantities and derived the gas and dust masses, dust-to-gas mass ratio, and core mass of the central star. About 80% of the total dust mass is from warm–cold dust component beyond ionization front. Comparison with other Galactic PNe indicates that Hen3-1357 is an ordinary amorphous silicate-rich and O-rich gas PN. Among other studied PNe, IC4846 shows many similarities in properties of the PN to Hen3-1357, although their post-AGB evolution is quite different from each other. Further monitoring of observations and comparisons with other PNe such as IC4846 are necessary to understand the evolution of Hen3-1357.

  9. The Anthropocene: A Planetary Perspective

    Science.gov (United States)

    Anbar, A. D.; Hartnett, H. E.; York, A.; Selin, C.

    2016-12-01

    The Anthropocene is a new planetary epoch defined by the emergence of human activity as one of the most important driving forces on Earth, rivaling and also stressing the other systems that govern the planet's habitability. Public discussions and debates about the challenges of this epoch tend to be polarized. One extreme denies that humans have a planetary-scale impact, while the other wishes that this impact could disappear. The tension between these perspectives is often paralyzing. Effective adaptation and mitigation requires a new perspective that reframes the conversation. We propose a planetary perspective according to which this epoch is the result of a recent major innovation in the 4 ­billion ­year history of life on Earth: the emergence of an energy-intensive planetary civilization. The rate of human energy use is already within an order of magnitude of that of the rest of the biosphere, and rising rapidly, and so this innovation is second only to the evolution of photosynthesis in terms of energy capture and utilization by living systems. Such energy use has and will continue to affect Earth at planetary scale. This reality cannot be denied nor wished away. From this pragmatic perspective, the Anthropocene is not an unnatural event that can be reversed, as though humanity is separate from the Earth systems with which we are co-evolving. Rather, it is an evolutionary transition to be managed. This is the challenge of turning a carelessly altered planet into a carefully designed and managed world, maintaining a "safe operating space" for human civilization (Steffen et al., 2011). To do so, we need an integrated approach to Earth systems science that considers humans as a natural and integral component of Earth's systems. Insights drawn from the humanities and the social sciences must be integrated with the natural sciences in order to thrive in this new epoch. This type of integrated perspective is relatively uncontroversial on personal, local, and even

  10. Blue light emitting thiogallate phosphor

    Science.gov (United States)

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  11. Transfer of polarized light in planetary atmospheres basic concepts and practical methods

    CERN Document Server

    Hovenier, Joop W; Domke, Helmut

    2004-01-01

    The principal elements of the theory of polarized light transfer in planetary atmospheres are expounded in a systematic but concise way. Basic concepts and practical methods are emphasized, both for single and multiple scattering of electromagnetic radiation by molecules and particles in the atmospheres of planets in the Solar System, including the Earth, and beyond. A large part of the book is also useful for studies of light scattering by particles in comets, the interplanetary and interstellar medium, circumstellar disks, reflection nebulae, water bodies like oceans and suspensions of particles in a gas or liquid in the laboratory. Throughout the book symmetry principles, such as the reciprocity principle and the mirror symmetry principle, are employed. In this way the theory is made more transparent and easier to understand than in most papers on the subject. In addition, significant computational reductions, resulting from symmetry principles, are presented. Hundreds of references to relevant literature ...

  12. Solar Variability and Planetary Climates

    CERN Document Server

    Calisesi, Y; Gray, L; Langen, J; Lockwood, M

    2007-01-01

    Variations in solar activity, as revealed by variations in the number of sunspots, have been observed since ancient times. To what extent changes in the solar output may affect planetary climates, though, remains today more than ever a subject of controversy. In 2000, the SSSI volume on Solar Variability and Climate reviewed the to-date understanding of the physics of solar variability and of the associated climate response. The present volume on Solar Variability and Planetary Climates provides an overview of recent advances in this field, with particular focus at the Earth's middle and lower atmosphere. The book structure mirrors that of the ISSI workshop held in Bern in June 2005, the collection of invited workshop contributions and of complementary introductory papers synthesizing the current understanding in key research areas such as middle atmospheric processes, stratosphere-troposphere dynamical coupling, tropospheric aerosols chemistry, solar storm influences, solar variability physics, and terrestri...

  13. Teaching, Learning, and Planetary Exploration

    Science.gov (United States)

    Brown, Robert A.

    2002-01-01

    This is the final report of a program that examined the fundamentals of education associated with space activities, promoted educational policy development in appropriate forums, and developed pathfinder products and services to demonstrate the utility of advanced communication technologies for space-based education. Our focus was on space astrophysics and planetary exploration, with a special emphasis on the themes of the Origins Program, with which the Principal Investigator (PI) had been involved from the outset. Teaching, Learning, and Planetary Exploration was also the core funding of the Space Telescope Science Institute's (ST ScI) Special Studies Office (SSO), and as such had provided basic support for such important NASA studies as the fix for Hubble Space Telescope (HST) spherical aberration, scientific conception of the HST Advanced Camera, specification of the Next-Generation Space Telescope (NGST), and the strategic plan for the second decade of the HST science program.

  14. The PSA: Planetary Science Archive

    Science.gov (United States)

    Barthelemy, M.; Martinez, S.; Heather, D.; Vazquez, J. L.; Arviset, C.; Osuna, P.; PSA development Team

    2012-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. Besides data from the GIOTTO spacecraft and several ground-based cometary observations, the PSA contains data from the Mars Express, Venus Express, Rosetta, SMART-1 and Huygens missions. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Advanced Search Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. By nature, this interface requires careful use and heavy interaction with the end-user to input and control the relevant search parameters. - The Map-based Interface is currently operational only for Mars Express HRCS and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Advanced interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Advanced interface. - The FTP Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All data are prepared by the corresponding instrument teams, mostly located in Europe. PSA supports the instrument teams in the full archiving process, from the definition of the data products, meta-data and product labels

  15. Numerical models of planetary dynamos

    International Nuclear Information System (INIS)

    Glatzmaier, G.A.; Roberts, P.H.

    1992-01-01

    We describe a nonlinear, axisymmetric, spherical-shell model of planetary dynamos. This intermediate-type dynamo model requires a prescribed helicity field (the alpha effect) and a prescribed buoyancy force or thermal wind (the omega effect) and solves for the axisymmetric time-dependent magnetic and velocity fields. Three very different time dependent solutions are obtained from different prescribed sets of alpha and omega fields

  16. Stream Lifetimes Against Planetary Encounters

    Science.gov (United States)

    Valsecchi, G. B.; Lega, E.; Froeschle, Cl.

    2011-01-01

    We study, both analytically and numerically, the perturbation induced by an encounter with a planet on a meteoroid stream. Our analytical tool is the extension of pik s theory of close encounters, that we apply to streams described by geocentric variables. The resulting formulae are used to compute the rate at which a stream is dispersed by planetary encounters into the sporadic background. We have verified the accuracy of the analytical model using a numerical test.

  17. Planetary rovers and data fusion

    OpenAIRE

    Masuku, Anthony Dumisani

    2012-01-01

    This research will investigate the problem of position estimation for planetary rovers. Diverse algorithmic filters are available for collecting input data and transforming that data to useful information for the purpose of position estimation process. The terrain has sandy soil which might cause slipping of the robot, and small stones and pebbles which can affect trajectory. The Kalman Filter, a state estimation algorithm was used for fusing the sensor data to improve the p...

  18. Gazetteer of planetary nomenclature 1994

    Science.gov (United States)

    Batson, Raymond M.; Russell, Joel F.

    1995-01-01

    Planetary nomenclature, like terrestrial nomenclature, is used to uniquely identify a feature on the surface of a planet or satellite so that the feature can be easily located, described, and discussed. This volume contains detailed information about all names of topographic and albedo features on planets and satellites (and some planetary ring and ring-gap systems) that the International Astronomical Union has named and approved from its founding in 1919 through its triennial meeting in 1994.This edition of the Gazetteer of Planetary Nomenclature supersedes an earlier informal volume distributed by the U.S. Geological Survey in 1986 as Open-File Report 84-692 (Masursky and others, 1986). Named features are depicted on maps of the Moon published first by the U.S. Defense Mapping Agency or the Aeronautical Chart and Information Center and more recently by the U.S. Geological Survey; on maps of Mercury, Venus, Mars, and the satellites of Jupiter, Saturn, and Uranus published by the U.S. Geological Survey; and on maps of the Moon, Venus, and Mars produced by the U.S.S.R.Although we have attempted to check the accuracy of all data in this volume, we realize that some errors will remain in a work of this size. Readers noting errors or omissions are urged to communicate them to the U.S. Geological Survey, Branch of Astrogeology, Rm. 409, 2255 N. Gemini Drive, Flagstaff, AZ 86001.

  19. The Coldest Object in the Universe: Probing the Mass Distribution of the Ultra-Cold Outflow and Dusty Disk in the Boomerang Nebula

    Science.gov (United States)

    Sahai, R.; Vlemmings, W.; Nyman, L. A.

    2014-01-01

    Our Cycle 0 ALMA observations confirmed that the Boomerang Nebula is the coldest known object in the universe, with a massive high-speed outflow that has cooled significantly below the temperature of the cosmic background (CMB). The Boomerang's prodigious mass-loss rate (0.001 solar mass M yr (exp -1) and low-luminosity (300L ) make it a key object for understanding the remarkable transition of the circumstellar envelopes of AGB stars into bipolar planetary nebulae. We have obtained new ACA CO 1-0 data that recover much of the flux lost in the Cycle O data, and reveal heretofore unseen distant regions of the ultra-cold outflow reheated to temperatures above the CMB. Our CO J=3-2 data reveal the precise, highly collimated shape of an inner bipolar structure and its dense central waist, with unprecedented angular resolution (0.4 in). The waist shows a core-halo structure in the thermal dust emission at 0.88 millimeter, and its derived flux at this wavelength, compared with the 3.3, 2.6, and 1.3 millimeter fluxes support the presence of about 5 x 10 (exp -4) solar mass of very large (approximately millimeter-sized), cold (approximately 30K) grains. We also find the unexpected presence of weak SO emission, possibly resulting from the release of S from grains due to high-speed shocks.

  20. Evolution of extra-galactic nebulae and the origin of metagalactic radio noise

    International Nuclear Information System (INIS)

    Bruce, C.E.R.

    1975-01-01

    It is pointed out that the discovery of the 'jet' in the radio source NGC 4486 fulfils a prediction made many years ago that such 'jets' would exist in some globular or elliptical nebulae. They are the channels of electrical discharges on a nebular scale then postulated, which will last for about 10 million years. It is emphasized that the discharge hypothesis would account for - 1. the existence of irregular nebulae; 2. the 'cataclysmic action' which Hubble regarded as required to account for the transition from nebulae of Type E to Type Sa; 3. the fact that the arms of spiral nebulae are never seen in process of formation; 4. the gathering of the matter towards the discharge channels by magnetic pinch effect; 5. the frequent occurrence of two diametrically opposed major arms; 6. the origin of radio waves throughout an extensive volume of space surrounding the 'jet' or discharge channel in NGC 4486; 7. the effect of one extra galactic nebula, NGC 3187, on another, NGC 3190; 8. the existence of diffuse patches of luminosity, 'emission nebulae', in the spiral arms of our own galaxy and in those of the 'Andromeda Nebula'. On the discharge theory about one per cent of all nebulae will be passing through the discharge phase at any one time, i.e., the number required to account for the observed intensity of metagalactic radio noise. (author)

  1. An Analysis of Spectra in the Red Rectangle Nebula Frédéric Zagury

    Indian Academy of Sciences (India)

    Abstract. This paper presents an analysis of a series of spectra in the. Red Rectangle nebula. Only the reddest part of the spectra can safely be attributed to light from the nebula, and indicates Rayleigh scattering by the gas, in conformity with the large angles of scattering involved and the prox- imity of the star. In the blue ...

  2. PPAK integral field spectroscopy survey of the Orion nebula. Data release

    NARCIS (Netherlands)

    Sánchez, S. F.; Cardiel, N.; Verheijen, M. A. W.; Martín-Gordón, D.; Vilchez, J. M.; Alves, J.

    2007-01-01

    Aims:We present a low-resolution spectroscopic survey of the Orion nebula. The data are released for public use. We show the possible applications of this dataset analyzing some of the main properties of the nebula. Methods: We perform an integral field spectroscopy mosaic of an area of ~5 arcmin× 6

  3. Disks, Microjets, Windblown Bubbles, and Outflows in the Orion Nebula

    Science.gov (United States)

    Bally, John; O'Dell, C. R.; McCaughrean, Mark J.

    2000-06-01

    New deep narrowband images of the Orion Nebula obtained with WFPC2 on the Hubble Space Telescope (HST) and spectra taken with the HIRES spectrometer at the Keck Observatory are presented. We report eight new circumstellar disks seen in silhouette against the background nebular light and about 30 dark disks embedded within the bright proplyds rimmed by ionization fronts. Deep narrowband λ6300 Å images reveal skins of glowing [O I] emission associated with several disks embedded within bright proplyds. [O I] emission also surrounds one dark disk not surrounded by an ionization front; this object may be embedded within the photon-dominated, mostly neutral region behind the ionization front of the Orion Nebula. The intensity and morphology of the [O I] emission provides support for the photon-dominated-region models of externally irradiated circumstellar disks in which soft UV powers photoablation of the disk surface. Dozens of outflows powered by young stars have been discovered on the new images. More than 20 stellar jets emerge from the externally irradiated circumstellar disks or their associated young stars embedded within the Nebula. Most are one-sided (monopolar) subarcsecond-scale microjets, too small to be seen on ground-based images against the bright background nebular light. Additionally, wide-angle winds from 10 young stars in the outskirts of the Nebula power large-scale bow shocks facing the Trapezium OB stars. These shocks may be produced by wind-wind interactions where the T-Tauri winds interact with the outflow of plasma from the core of M42. The largest such structure, associated with the star LL Ori, contains a number of compact high-proper-motion clumps moving almost tangentially to the bow shock. The new data are combined with older HST images to determine proper motions for many nebular features. Neither the LL Ori type bow shocks in the outskirts of the nebula nor the Hα + [O III] arcs that surround many proplyds near the Trapezium show

  4. Models for circumstellar nebulae around red and blue supergiants

    Science.gov (United States)

    Chita, S. M.

    2011-10-01

    In this thesis, we model the circumstellar medium of stars with initial masses of 8, 12, 18 and 20 solar masses, over their entire life from the main sequence until their supernova explosion. During the post-main-sequence stages, stars can evolve through several blue and red supergiant stages depending on their initial mass, composition and rotation rate. The models considered in the second Chapter have long-lasting RSG stages starting after the MS. In this phase, they develop shells of RSG wind material at the location where the free streaming RSG wind is stalled by the thermal pressure of the hot MS bubble, close to the central star. The RSG shells develop violent Rayleigh-Taylor instabilities. Once these start to grow non-linear, the RSG shell becomes highly structured as clumps form, and shell material mixes with material in the hot bubble. Later, the stars evolve to the BSG stage, during which the RSG shells are completely destroyed. These models return to the RSG stage, and build new RSG shells, which are more massive than those formed earlier. RSG shells are essential for our understanding of bipolar emission nebulae around BSGs. In the third Chapter are shown the results of the wind-wind interaction model of single star with 12 solar masses. On a time scale of a few 10000 yr, a BSG hour-glas shaped nebula expands into the sphere defined by the RSG shell. The faster polar parts of the hour glass hit the inner edge of the RSG shell first. The collision creates a pair of hot and dense polar caps. As time passes, the collision zone moves to lower latitudes of the RSG shell and becomes more confined in latitude. At the same time, the interaction of the BSG wind with the equatorial disk defines a second, ring shaped collision zone in the equatorial plane. These structures are reminiscent of the observed nebulae around the blue supergiant Sher 25. In the Chapter 3 we present calculations that predict the properties of the circumstellar medium for rapidly rotating

  5. Collisional stripping of planetary crusts

    Science.gov (United States)

    Carter, Philip J.; Leinhardt, Zoë M.; Elliott, Tim; Stewart, Sarah T.; Walter, Michael J.

    2018-02-01

    Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of 'crustal stripping' during accretion and its key geochemical consequences. Crusts are expected to contain a significant fraction of planetary budgets of incompatible elements, which include the major heat producing nuclides. We present smoothed particle hydrodynamics simulations of collisions between differentiated rocky planetesimals and planetary embryos. We find that the crust is preferentially lost relative to the mantle during impacts, and we have developed a scaling law based on these simulations that approximates the mass of crust that remains in the largest remnant. Using this scaling law and a recent set of N-body simulations of terrestrial planet formation, we have estimated the maximum effect of crustal stripping on incompatible element abundances during the accretion of planetary embryos. We find that on average approximately one third of the initial crust is stripped from embryos as they accrete, which leads to a reduction of ∼20% in the budgets of the heat producing elements if the stripped crust does not reaccrete. Erosion of crusts can lead to non-chondritic ratios of incompatible elements, but the magnitude of this effect depends sensitively on the details of the crust-forming melting process on the planetesimals. The Lu/Hf system is fractionated for a wide range of crustal formation scenarios. Using eucrites (the products of planetesimal silicate melting, thought to represent the crust of Vesta) as a guide to the Lu/Hf of planetesimal crust partially lost during accretion, we predict the Earth could evolve to a superchondritic 176Hf/177Hf (3-5 parts per ten thousand) at present day. Such values are in keeping with compositional estimates of the bulk Earth. Stripping of planetary crusts during accretion can lead to

  6. MAPPING THE POLARIZATION OF THE RADIO-LOUD Ly α NEBULA B3 J2330+3927

    Energy Technology Data Exchange (ETDEWEB)

    You, Chang; Zabludoff, Ann; Smith, Paul; Jannuzi, Buell [Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721 (United States); Yang, Yujin [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Kim, Eunchong; Lee, Myung Gyoon [Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 88226 (Korea, Republic of); Prescott, Moire K. M. [Department of Astronomy, New Mexico State University, 1320 Frenger Mall, Las Cruces, NM 88003 (United States); Matsuda, Yuichi, E-mail: yyang@kasi.re.kr [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2017-01-10

    Ly α nebulae, or “Ly α blobs,” are extended (up to ∼100 kpc), bright (L{sub Lyα}  ≳ 10{sup 43} erg s{sup −1}) clouds of Ly α emitting gas that tend to lie in overdense regions at z  ∼ 2–5. The origin of the Ly α emission remains unknown, but recent theoretical work suggests that measuring the polarization might discriminate among powering mechanisms. Here we present the first narrowband imaging polarimetry of a radio-loud Ly α nebula, B3 J2330+3927, at z = 3.09, with an embedded active galactic nucleus (AGN). The AGN lies near the blob’s Ly α emission peak, and its radio lobes align roughly with the blob’s major axis. With the SPOL polarimeter on the 6.5 m MMT telescope, we map the total (Ly α + continuum) polarization in a grid of circular apertures of a radius of 0.″6 (4.4 kpc), detecting a significant (>2 σ ) polarization fraction P {sub %} in nine apertures and achieving strong upper limits (as low as 2%) elsewhere. P{sub %} increases from <2% at ∼5 kpc from the blob center to 17% at ∼15–25 kpc. The detections are distributed asymmetrically, roughly along the nebula’s major axis. The polarization angles θ are mostly perpendicular to this axis. Comparing the Ly α flux to that of the continuum and conservatively assuming that the continuum is highly polarized (20%–100%) and aligned with the total polarization, we place lower limits on the polarization of the Ly α emission P{sub %,Lyα} ranging from no significant polarization at ∼5 kpc from the blob center to 3%–17% at 10–25 kpc. Like the total polarization, the Ly α polarization detections occur more often along the blob’s major axis.

  7. The origin of magnetic fields in protoplanetary nebulae

    Science.gov (United States)

    Pascoli, Gianni; Leclercq, Josette

    1989-04-01

    The hypothesis that the magnetic fields of protoplanetary nebulae are generated deep in the core of the progenitor, an evolved M-type red giant, is explored. An examination of the transport of magnetic field lines through the convective envelope and of diffusion in the stellar wind/photosphere transition zone reveals values of about 10 G for the subphotospheric magnetic field and of about 2-3 G at the base of the stellar wind. The results are in agreement with the findings of Pascoli (1987) and Pascoli and Macron (1987).

  8. The Radio Spectral Index of the Crab Nebula

    Science.gov (United States)

    1997-11-20

    provision of law , no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid...Nebula either, so the spectrum near the edge maintains its power law form at least down to 74 MHz. The uniformity of the spectral index throughout the... Walra -(Oort ven This feature is moving outward,1956 ; Scargle 1969). and in the radio, it seems to have a sharp outward edge (BK92). Since our 327

  9. Early-type objects in NGC6611 and Eagle Nebula

    OpenAIRE

    Martayan, Christophe; Floquet, Michele; Hubert, Anne-Marie; Neiner, Coralie; Fremat, Yves; Baade, Dietrich; Fabregat, Juan

    2008-01-01

    An important question about Be stars is whether Be stars are born as Be stars or not. It is necessary to observe young clusters to answer this question. Observations of stars in NGC6611 and the star-formation region of Eagle Nebula have been carried out with the ESO-WFI in slitless spectroscopic mode and at the VLT-GIRAFFE. The targets for the GIRAFFE observations were pre-selected from the literature and our catalogue of emission-line stars (ELS) based on the WFI study. GIRAFFE observations ...

  10. Interstellar Organics, the Solar Nebula, and Saturn's Satellite Phoebe

    Science.gov (United States)

    Pendleton, Y. J.; Cruikshank, D. P.

    2014-01-01

    The diffuse interstellar medium inventory of organic material (Pendleton et al. 1994, Pendleton & Allamandola 2002) was likely incorporated into the molecular cloud in which the solar nebula condensed. This provided the feedstock for the formation of the Sun, major planets, and the smaller icy bodies in the region outside Neptune's orbit (transneptunian objects, or TNOs). Saturn's satellites Phoebe, Iapetus, and Hyperion open a window to the composition of one class of TNO as revealed by the near-infrared mapping spectrometer (VIMS) on the Cassini spacecraft at Saturn. Phoebe (mean diameter 213 km) is a former TNO now orbiting Saurn. VIMS spaectral maps of PHoebe's surface reveal a complex organic spectral signature consisting of prominent aromatic (CH) and alophatic hydrocarbon (CH2, CH3) absorption bands (3.2-3.6 micrometers). Phoebe is the source of a huge debris ring encircling Saturn, and from which particles (approximately 5-20 micrometer size) spiral inward toward Saturn. They encounter Iapetus and Hperion where they mix with and blanket the native H2O ice of those two bodies. Quantitative analysis of the hydrocarbon bands on Iapetus demonstrates that aromatic CH is approximately 10 times as abundant as aliphatic CH2+CH3, significantly exceeding the strength of the aromatic signature in interplanetary dust particles, comet particles, ad in carbonaceous meteorites (Cruikshank et al. 2013). A similar excess of aromatics over aliphatics is seen in the qualitative analysis of Hyperion and Phoebe itself (Dalle Ore et al. 2012). The Iapetus aliphatic hydrocarbons show CH2/CH3 approximately 4, which is larger than the value found in the diffuse ISM (approximately 2-2.5). In so far as Phoebe is a primitive body that formed in the outer regions of the solar nebula and has preserved some of the original nebula inventory, it can be key to understanding the content and degree of procesing of the nebular material. There are other Phoebe-like TNOs that are presently

  11. Volcanic Degassing and the Atmosphere of Planetary Suites

    Science.gov (United States)

    Gaillard, F.; Scaillet, B.

    2012-12-01

    How unique the Earth is requires an urgent definition in front of the myriad of spatial observations revealing extra solar planets with variable spectral signatures. In the close solar system, high water abundance, atmospheric pressure at 1 bar and an O2-rich atmosphere constitute the main features of the Earth surface. This contrasts with dry Venus and its nearly 100 bar of reduced atmosphere dominated by CO2. This also contrasts with Mars, once flowed by water, today dominated by sulphate deposits, with 0.01 bar of atmospheric pressure and its oxidized surface. Such diversity in the physic and chemistry of planetary surfaces constitutes our most robust observation and benchmark for deciphering the remote exoplanets and defining the possible development of clement conditions for extra-terrestrial life. Volcanic degassing is a fundamental planetary process that conveys igneous volatiles species regulating important physical and chemical features of the exosphere. Understanding the planetary chemical fix supplied by volcanoes and how it can vary is therefore critical for a better definition of systems favorable to life emergence. We show that the atmospheric pressure, defining the minimum pressure of volcanic degassing, is the chief parameter controlling the composition of volcanic gases. On Venus, volcanic degassing occurring at minimum pressure of 100 bar can only be composed of CO2, whereas water and sulfur remain dissolved in the lavas. This explains the dry Venusian atmosphere. Degassing at 1 bar (minimum) on Earth produces mixtures dominated by water, explaining the Earth's wet surface. On Mars, gases produced at less than 0.05 bar contain more sulfur than water and Jupiter moon, Io, emits, in vacuum, gases that are dominated by sulfite. The composition of volcanic gases is therefore merely regulated by the atmospheric pressure. The latter is, in turn, mainly controlled by the size of the planet, even if little certitude exists about the most influential

  12. The evolution of solar ultraviolet luminosity. [influence on planetary atmospheres

    Science.gov (United States)

    Zahnle, K. J.; Walker, J. C. G.

    1982-01-01

    Astronomical observations of stars analogous to the sun are used to construct a tentative account of the evolution of solar UV luminosity. Evidence exists that the young sun was a much more powerful source of energetic particles and radiation than it is today, and while on the main sequence, solar activity has declined as an inverse power law of age as a consequence of angular momentum loss to the solar wind. Observations of pre-main sequence stars indicate that before the sun reached the main sequence, it may have emitted as much as ten thousand times the amount of ultraviolet radiation that it does today. The impact of the results on knowledge of photochemistry and escape of constituents of primordial planetary atmospheres is discussed.

  13. The Planetary Data System— Archiving Planetary Data for the use of the Planetary Science Community

    Science.gov (United States)

    Morgan, Thomas H.; McLaughlin, Stephanie A.; Grayzeck, Edwin J.; Vilas, Faith; Knopf, William P.; Crichton, Daniel J.

    2014-11-01

    NASA’s Planetary Data System (PDS) archives, curates, and distributes digital data from NASA’s planetary missions. PDS provides the planetary science community convenient online access to data from NASA’s missions so that they can continue to mine these rich data sets for new discoveries. The PDS is a federated system consisting of nodes for specific discipline areas ranging from planetary geology to space physics. Our federation includes an engineering node that provides systems engineering support to the entire PDS.In order to adequately capture complete mission data sets containing not only raw and reduced instrument data, but also calibration and documentation and geometry data required to interpret and use these data sets both singly and together (data from multiple instruments, or from multiple missions), PDS personnel work with NASA missions from the initial AO through the end of mission to define, organize, and document the data. This process includes peer-review of data sets by members of the science community to ensure that the data sets are scientifically useful, effectively organized, and well documented. PDS makes the data in PDS easily searchable so that members of the planetary community can both query the archive to find data relevant to specific scientific investigations and easily retrieve the data for analysis. To ensure long-term preservation of data and to make data sets more easily searchable with the new capabilities in Information Technology now available (and as existing technologies become obsolete), the PDS (together with the COSPAR sponsored IPDA) developed and deployed a new data archiving system known as PDS4, released in 2013. The LADEE, MAVEN, OSIRIS REx, InSight, and Mars2020 missions are using PDS4. ESA has adopted PDS4 for the upcoming BepiColumbo mission. The PDS is actively migrating existing data records into PDS4 and developing tools to aid data providers and users. The PDS is also incorporating challenge

  14. Planetary resources and astroecology. Planetary microcosm models of asteroid and meteorite interiors: electrolyte solutions and microbial growth--implications for space populations and panspermia.

    Science.gov (United States)

    Mautner, Michael N

    2002-01-01

    Planetary microcosms were constructed using extracts from meteorites that simulate solutions in the pores of carbonaceous chondrites. The microcosms were found to support the growth of complex algal and microbial populations. Such astroecology experiments demonstrate how a diverse ecosystem could exist in fluids within asteroids, and in meteorites that land on aqueous planets. The microcosm solutions were obtained by extracting nutrient electrolytes under natural conditions from powders of the Allende (CV3) and Murchison (CM2) meteorites at low (0.02 g/ml) and high (10.0 g/ml) solid/solution ratios. The latter solutions contain > 3 mol/L electrolytes and about 10 g/L organics, that simulate natural fluids in asteroids during aqueous alteration and in the pores of meteorites, which can help prebiotic synthesis and the survival of early microorganisms. These solutions and wet solids were in fact found to support complex self-sustaining microbial communities with populations of 4 x 10(5) algae and 6 x 10(6) bacteria and fungi for long periods (> 8 months). The results show that planetary microcosms based on meteorites can: assay the fertilities of planetary materials; identify space bioresources; target astrobiology exploration; and model past and future space-based ecosystems. The results show that bioresources in the carbonaceous asteroids can sustain a biomass of 10(18) kg, comprising 10(32) microorganisms and a human population of 10(14). The results also suggest that protoplanetary nebulae can support and disperse microorganisms and can be therefore effective environments for natural and directed panspermia.

  15. Teaching, learning, and planetary exploration

    Science.gov (United States)

    Brown, Robert A.

    1992-01-01

    The progress accomplished in the first five months of the three-year grant period of Teaching, Learning, and Planetary Exploration is presented. The objectives of this project are to discover new education products and services based on space science, particularly planetary exploration. An Exploration in Education is the umbrella name for the education projects as they are seen by teachers and the interested public. As described in the proposal, our approach consists of: (1) increasing practical understanding of the potential role and capabilities of the research community to contribute to basic education using new discoveries; (2) developing an intellectual framework for these contributions by supplying criteria and templates for the teacher's stories; (3) attracting astronomers, engineers, and technical staff to the project and helping them form productive education partnerships for the future, (4) exploring relevant technologies and networks for authoring and communicating the teacher's stories; (5) enlisting the participation of potential user's of the teacher's stories in defining the products; (6) actually producing and delivering many educationally useful teacher's stories; and (7) reporting the pilot study results with critical evaluation. Technical progress was made by assembling our electronic publishing stations, designing electronic publications based on space science, and developing distribution approaches for electronic products. Progress was made addressing critical issues by developing policies and procedures for securing intellectual property rights and assembling a focus group of teachers to test our ideas and assure the quality of our products. The following useful materials are being produced: the TOPS report; three electronic 'PictureBooks'; one 'ElectronicArticle'; three 'ElectronicReports'; ten 'PrinterPosters'; and the 'FaxForum' with an initial complement of printed materials. We have coordinated with planetary scientists and astronomers

  16. The Integral Field View of the Orion Nebula

    Directory of Open Access Journals (Sweden)

    Adal Mesa-Delgado

    2014-01-01

    Full Text Available This paper reviews the major advances achieved in the Orion Nebula through the use of integral field spectroscopy (IFS. Since the early work of Vasconcelos and collaborators in 2005, this technique has facilitated the investigation of global properties of the nebula and its morphology, providing new clues to better constrain its 3D structure. IFS has led to the discovery of shock-heated zones at the leading working surfaces of prominent Herbig-Haro objects as well as the first attempt to determine the chemical composition of Orion protoplanetary disks, also known as proplyds. The analysis of these morphologies using IFS has given us new insights into the abundance discrepancy problem, a long-standing and unresolved issue that casts doubt on the reliability of current methods used for the determination of metallicities in the universe from the analysis of H II regions. Results imply that high-density clumps and high-velocity flows may play an active role in the production of such discrepancies. Future investigations based on the large-scale IFS mosaic of Orion will be very valuable for exploring how the integrated effect of small-scale structures may have impact at larger scales in the framework of star-forming regions.

  17. The Crab nebula's ''wisps'' as shocked pulsar wind

    International Nuclear Information System (INIS)

    Gallant, Y.A.; Arons, J.; Langdon, A.B.

    1992-01-01

    The Crab synchrotron nebula has been successfully modelled as the post-shock region of a relativistic, magnetized wind carrying most of the spindown luminosity from the central pulsar. While the Crab is the best-studied example, most of the highest spindown luminosity pulsars are also surrounded by extended synchrotron nebulae, and several additional supernova remnants with ''plerionic'' morphologies similar to the Crab are known where the central object is not seen. All these objects have nonthermal, power-law spectra attributable to accelerated high-energy particles thought to originate in a Crab-like relativistic pulsar wind. However, proposed models have so far treated the wind shock as an infinitesimally thin discontinuity, with an arbitrarily ascribed particle acceleration efficiency. To make further progress, investigations resolving the shock structure seemed in order. Motivated by these considerations, we have performed ''particle-in-cell (PIC) simulations of perpendicularly magnetized shocks in electron-positron and electron-positron-ion plasmas. The shocks in pure electron-positron plasmas were found to produce only thermal distributions downstream, and are thus poor candidates as particle acceleration sites. When the upstream plasma flow also contained a smaller population of positive ions, however, efficient acceleration of positrons, and to a lesser extent of electrons, was observed in the simulations

  18. Gigahertz-peaked spectra pulsars in Pulsar Wind Nebulae

    Science.gov (United States)

    Basu, R.; RoŻko, K.; Kijak, J.; Lewandowski, W.

    2018-04-01

    We have carried out a detailed study of the spectral nature of six pulsars surrounded by pulsar wind nebulae (PWNe). The pulsar flux density was estimated using the interferometric imaging technique of the Giant Metrewave Radio Telescope at three frequencies 325, 610, and 1280 MHz. The spectra showed a turnover around gigahertz frequency in four out of six pulsars. It has been suggested that the gigahertz-peaked spectrum (GPS) in pulsars arises due to thermal absorption of the pulsar emission in surrounding medium like PWNe, H II regions, supernova remnants, etc. The relatively high incidence of GPS behaviour in pulsars surrounded by PWNe imparts further credence to this view. The pulsar J1747-2958 associated with the well-known Mouse nebula was also observed in our sample and exhibited GPS behaviour. The pulsar was detected as a point source in the high-resolution images. However, the pulsed emission was not seen in the phased-array mode. It is possible that the pulsed emission was affected by extreme scattering causing considerable smearing of the emission at low radio frequencies. The GPS spectra were modelled using the thermal free-free absorption and the estimated absorber properties were largely consistent with PWNe. The spatial resolution of the images made it unlikely that the point source associated with J1747-2958 was the compact head of the PWNe, but the synchrotron self-absorption seen in such sources was a better fit to the estimated spectral shape.

  19. Two different sources of water for the early solar nebula.

    Science.gov (United States)

    Kupper, Stefan; Tornow, Carmen; Gast, Philipp

    2012-06-01

    Water is essential for life. This is a trivial fact but has profound implications since the forming of life on the early Earth required water. The sources of water and the related amount of delivery depend not only on the conditions on the early Earth itself but also on the evolutionary history of the solar system. Thus we ask where and when water formed in the solar nebula-the precursor of the solar system. In this paper we explore the chemical mechanics for water formation and its expected abundance. This is achieved by studying the parental cloud core of the solar nebula and its gravitational collapse. We have identified two different sources of water for the region of Earth's accretion. The first being the sublimation of the icy mantles of dust grains formed in the parental cloud. The second source is located in the inner region of the collapsing cloud core - the so-called hot corino with a temperature of several hundred Kelvin. There, water is produced efficiently in the gas phase by reactions between neutral molecules. Additionally, we analyse the dependence of the production of water on the initial abundance ratio between carbon and oxygen.

  20. Observation and Spectral Measurements of the Crab Nebula with Milagro

    Science.gov (United States)

    Abdo, A. A.; Allen, B. T.; Aune, T.; Benbow, W.; Berley, D.; Chen, C.; Christopher, G. E.; DeYoung, T.; Dingus, B. L.; Falcone, A.; hide

    2011-01-01

    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV - 100 TeV gamma ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between 1 and 100 TeV. The TeV emission is believed to be caused by inverse-Compton up-scattering scattering of ambient photons by an energetic electron population. The location of a Te V steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fit.

  1. Institute of Geophysics, Planetary Physics, and Signatures

    Data.gov (United States)

    Federal Laboratory Consortium — The Institute of Geophysics, Planetary Physics, and Signatures at Los Alamos National Laboratory is committed to promoting and supporting high quality, cutting-edge...

  2. Sealed Planetary Return Canister (SPRC), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Sample return missions have primary importance in future planetary missions. A basic requirement is that samples be returned in pristine, uncontaminated condition,...

  3. Polarimetry of stars and planetary systems

    National Research Council Canada - National Science Library

    Kolokolova, Ludmilla; Hough, James; Levasseur-Regourd, Anny-Chantal

    2015-01-01

    ... fields of polarimetric exploration, including proto-planetary and debris discs, icy satellites, transneptunian objects, exoplanets and the search for extraterrestrial life -- unique results produced...

  4. Sealed Planetary Return Canister (SPRC), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Sample return missions have primary importance in future planetary missions. A basic requirement is that samples be returned in pristine, uncontaminated condition,...

  5. Examples of Radiation-Emitting Products

    Science.gov (United States)

    Examples of Radiation-Emitting Electronic Products Radiation Use Medical: Diagnostic Medical: Therapeutic Medical: Surgical Medical: Other Scientific, ... FDA Enforcement Authorities for Radiation-Emitting Products (with examples of products) RCHSA Television Receivers, Microwave Ovens, Cabinet ...

  6. Public Participation in Planetary Exploration

    Science.gov (United States)

    Friedman, Louis

    2000-07-01

    In the past several years The Planetary Society has created several innovative opportunities for general public participation in the exploration of the solar system and the search for extraterrestrial life. The conduct of such exploration has traditionally been the province of a few thousand, at most, of professionally involved scientists and engineers. Yet the rationale for spending resources required by broad and far-reaching exploration involves a greater societal interest - it frequently being noted that the rationale cannot rely on science alone. This paper reports on the more notable of the opportunities for general public participation, in particular: 1) Visions of Mars: a CD containing the works of science fiction about Mars, designed to be placed on Mars as the first library to be found by eventual human explorers; 2) MAPEX: a Microelectronics And Photonics Experiment, measuring the radiation environment for future human explorers of Mars, and containing a electron beam lithograph of names of all the members of The Planetary Society at a particular time; 3) Naming of spacecraft: Involvement in the naming of spacecraft: Magellan, Sojourner; 4) The Mars Microphone: the first privately funded instrument to be sent to another world; 5) Red Rover Goes to Mars: the first commercial-education partnership on a planetary mission; 6) Student designed nanoexperiments: to fly on a Mars lander; and 7) SETI@home: a tool permitting millions to contribute to research and data processing in the search for extraterrestrial intelligence. A brief description of each of the projects will be given, and the opportunity it provided for public participation described. The evolving complexity of these projects suggest that more opportunities will be found, and that the role of public participation can increase at the same time as making substantive contributions to the flight missions. It will be suggested that these projects presage the day that planetary exploration will be truly

  7. PSUP: A Planetary SUrface Portal

    Science.gov (United States)

    Poulet, F.; Quantin-Nataf, C.; Ballans, H.; Dassas, K.; Audouard, J.; Carter, J.; Gondet, B.; Lozac'h, L.; Malapert, J.-C.; Marmo, C.; Riu, L.; Séjourné, A.

    2018-01-01

    The large size and complexity of planetary data acquired by spacecraft during the last two decades create a demand within the planetary community for access to the archives of raw and high level data and for the tools necessary to analyze these data. Among the different targets of the Solar System, Mars is unique as the combined datasets from the Viking, Mars Global Surveyor, Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter missions provide a tremendous wealth of information that can be used to study the surface of Mars. The number and the size of the datasets require an information system to process, manage and distribute data. The Observatories of Paris Sud (OSUPS) and Lyon (OSUL) have developed a portal, called PSUP (Planetary SUrface Portal), for providing users with efficient and easy access to data products dedicated to the Martian surface. The objectives of the portal are: 1) to allow processing and downloading of data via a specific application called MarsSI (Martian surface data processing Information System); 2) to provide the visualization and merging of high level (image, spectral, and topographic) products and catalogs via a web-based user interface (MarsVisu), and 3) to distribute some of these specific high level data with an emphasis on products issued by the science teams of OSUPS and OSUL. As the MarsSI service is extensively described in a companion paper (Quantin-Nataf et al., companion paper, submitted to this special issue), the present paper focus on the general architecture and the functionalities of the web-based user interface MarsVisu. This service provides access to many data products for Mars: albedo, mineral and thermal inertia global maps from spectrometers; mosaics from imagers; image footprints and rasters from the MarsSI tool; high level specific products (defined as catalogs or vectors). MarsVisu can be used to quickly assess the visualized processed data and maps as well as identify areas that have not been mapped yet

  8. Planetary Radars Operating Centre PROC

    Science.gov (United States)

    Catallo, C.; Flamini, E.; Seu, R.; Alberti, G.

    2007-12-01

    Planetary exploration by means of radar systems, mainly using Ground Penetrating Radars (GPR) plays an important role in Italy. Numerous scientific international space programs are currently carried out jointly with ESA and NASA by Italian Space Agency, the scientific community and the industry. Three important experiments under Italian leadership ( designed and manufactured by the Italian industry), provided by ASI either as contribution to ESA programs either within a NASA/ASI joint venture framework, are now operating: MARSIS on-board Mars Express, SHARAD on-board Mars Reconnaissance Orbiter and CASSINI Radar on-board Cassini spacecraft. In order to support all the scientific communities, institutional customers and experiment teams operation three Italian dedicated operational centers have been realized, namely SHOC, (Sharad Operating Centre), MOC (Marsis Operating Center) and CASSINI PAD ( Processing Altimetry Data). Each center is dedicated to a single instrument management and control, data processing and distribution. Although they had been conceived to operate autonomously and independently one from each other, synergies and overlaps have been envisaged leading to the suggestion of a unified center, the Planetary Radar Processing Center (PROC). PROC is conceived in order to include the three operational centers, namely SHOC, MOC and CASSINI PAD, either from logistics point of view and from HW/SW capabilities point of view. The Planetary Radar Processing Center shall be conceived as the Italian support facility to the scientific community for on-going and future Italian planetary exploration programs. Therefore, scalability, easy use and management shall be the design drivers. The paper describes how PROC is designed and developed, to allow SHOC, MOC and CASSINI PAD to operate as before, and to offer improved functionalities to increase capabilities, mainly in terms of data exchange, comparison, interpretation and exploitation. Furthermore, in the frame of

  9. The Chlorine Isotope Composition of the Solar Nebula & Implications to the Sources of Volatiles to the Terrestrial Planets

    Science.gov (United States)

    Gargano, A. M.; Sharp, Z. D.

    2017-12-01

    It was originally proposed by Sharp et al., 2016 that the solar nebula was isotopically light based on limited sampling of the Ol-phyric shergottites and two ordinary chondrites (Parnallee LL3.00, and NWA 8276 L3.00). Iron meteorites are remnants of early planetesimals which segregated cores planets is commonly assumed to be chondritic in origin. These preliminary chlorine isotope data suggest that early planetesimals and planetary embryos had a solar Cl component at -7‰ or less, and secondary processes has since increased the δ37Cl values of Earth, Mars, and most chondrites. The chlorine isotope system therefore provides a new constraint regarding the sources of volatiles to the terrestrial planets. The δ37Cl value of the bulk Earth is around 0‰, inconsistent with a nebular source as measured in the Martian mantle but similar to that of chondrites with HCl clathrate precursors. The prolonged accretion of heavy chondritic material to Earth can account for the chlorine isotope discrepancy between the Earth and Mars, but is unconstrained by HSE abundances before complete core-mantle differentiation. Here, we examine the amount of chondritic chlorine and water that can added to the Earth allowable by HSE abundances and explore other potential sources of volatiles to the terrestrial planets to account for isotopic and elemental discrepancies.

  10. He II Raman Scattered Line by Neutral Hydrogen in the Bipolar Platenary Nebula M2-9

    Directory of Open Access Journals (Sweden)

    Hee-Won Lee

    2001-06-01

    Full Text Available In the spectrum of the young bipolar planetary nebula M2-9 obtained from the 1.5 m telescope at the Cerro Tololo Inter-American Observatory, we detected the He~II feature at 6545 Å that are proposed to be formed via Raman scattering by atomic hydrogen. However, in the same spectrum, the He~II emission lines at 6527 Å and 6560 Å are absent, which implies that the He~II emission region is hidden from our line of sight and that the H~I scattering region is pretty much extended not to be obscured entirely. We performed photoionization computations to estimate the physical size of the He~II emission line region to be 1016 cm, from which the location and dimension of the obscuring circumstellar region are inferred and the temperature of the central star must exceed 105 K. The angular size of the circumstellar region responsible for the obscuration of the He~II emission region is ~ 1'' with the assumption of the distance 01 kpc to M2-9, which is consistent with the recent image of M2-9 obtained with the Hubble Space Telescope.

  11. A Self-Perpetuating Catalyst for the Production of Complex Organic Molecules in Protostellar Nebulae

    Science.gov (United States)

    Nuth, Joseph A.; Johnson, N. M.

    2010-01-01

    The formation of abundant carbonaceous material in meteorites is a long standing problem and an important factor in the debate on the potential for the origin of life in other stellar systems. Many mechanisms may contribute to the total organic content in protostellar nebulae, ranging from organics formed via ion-molecule and atom-molecule reactions in the cold dark clouds from which such nebulae collapse, to similar ion-molecule and atom-molecule reactions in the dark regions of the nebula far from the proto star, to gas phase reactions in sub-nebulae around growing giant planets and in the nebulae themselves. The Fischer-Tropsch-type (FTT) catalytic reduction of CO by hydrogen was once the preferred model for production of organic materials in the primitive solar nebula. The Haber-Bosch catalytic reduction of N2 by hydrogen was thought to produce the reduced nitrogen found in meteorites. However, the clean iron metal surfaces that catalyze these reactions are easily poisoned via reaction with any number of molecules, including the very same complex organics that they produce and both reactions work more efficiently in the hot regions of the nebula. We have demonstrated that many grain surfaces can catalyze both FTT and HB-type reactions, including amorphous iron and magnesium silicates, pure silica smokes as well as several minerals. Although none work as well as pure iron grains, and all produce a wide range of organic products rather than just pure methane, these materials are not truly catalysts.

  12. Energetic Techniques For Planetary Defense

    Science.gov (United States)

    Barbee, B.; Bambacus, M.; Bruck Syal, M.; Greenaugh, K. C.; Leung, R. Y.; Plesko, C. S.

    2017-12-01

    Near-Earth Objects (NEOs) are asteroids and comets whose heliocentric orbits tend to approach or cross Earth's heliocentric orbit. NEOs of various sizes periodically collide with Earth, and efforts are currently underway to discover, track, and characterize NEOs so that those on Earth-impacting trajectories are discovered far enough in advance that we would have opportunities to deflect or destroy them prior to Earth impact, if warranted. We will describe current efforts by the National Aeronautics and Space Administration (NASA) and the National Nuclear Security Administration (NNSA) to assess options for energetic methods of deflecting or destroying hazardous NEOs. These methods include kinetic impactors, which are spacecraft designed to collide with an NEO and thereby alter the NEO's trajectory, and nuclear engineering devices, which are used to rapidly vaporize a layer of NEO surface material. Depending on the amount of energy imparted, this can result in either deflection of the NEO via alteration of its trajectory, or robust disruption of the NEO and dispersal of the remaining fragments. We have studied the efficacies and limitations of these techniques in simulations, and have combined the techniques with corresponding spacecraft designs and mission designs. From those results we have generalized planetary defense mission design strategies and drawn conclusions that are applicable to a range of plausible scenarios. We will present and summarize our research efforts to date, and describe approaches to carrying out planetary defense missions with energetic NEO deflection or disruption techniques.

  13. Interactive investigations into planetary interiors

    Science.gov (United States)

    Rose, I.

    2015-12-01

    Many processes in Earth science are difficult to observe or visualize due to the large timescales and lengthscales over which they operate. The dynamics of planetary mantles are particularly challenging as we cannot even look at the rocks involved. As a result, much teaching material on mantle dynamics relies on static images and cartoons, many of which are decades old. Recent improvements in computing power and technology (largely driven by game and web development) have allowed for advances in real-time physics simulations and visualizations, but these have been slow to affect Earth science education.Here I demonstrate a teaching tool for mantle convection and seismology which solves the equations for conservation of mass, momentum, and energy in real time, allowing users make changes to the simulation and immediately see the effects. The user can ask and answer questions about what happens when they add heat in one place, or take it away from another place, or increase the temperature at the base of the mantle. They can also pause the simulation, and while it is paused, create and visualize seismic waves traveling through the mantle. These allow for investigations into and discussions about plate tectonics, earthquakes, hot spot volcanism, and planetary cooling.The simulation is rendered to the screen using OpenGL, and is cross-platform. It can be run as a native application for maximum performance, but it can also be embedded in a web browser for easy deployment and portability.

  14. Visual lunar and planetary astronomy

    CERN Document Server

    Abel, Paul G

    2013-01-01

    With the advent of CCDs and webcams, the focus of amateur astronomy has to some extent shifted from science to art. The object of many amateur astronomers is now to produce “stunning images” that, although beautiful, are not intended to have scientific merit. Paul Abel has been addressing this issue by promoting visual astronomy wherever possible – at talks to astronomical societies, in articles for popular science magazines, and on BBC TV’s The Sky at Night.   Visual Lunar and Planetary Astronomy is a comprehensive modern treatment of visual lunar and planetary astronomy, showing that even in the age of space telescopes and interplanetary probes it is still possible to contribute scientifically with no more than a moderately priced commercially made astronomical telescope.   It is believed that imaging and photography is somehow more objective and more accurate than the eye, and this has led to a peculiar “crisis of faith” in the human visual system and its amazing processing power. But by anal...

  15. Planetary Stoichiometry, Mineral Ecology, and the Rise of Habitability

    Science.gov (United States)

    Hazen, R. M.; Downs, R. T.; Golden, J.; Hystad, G.; Grew, E. S.

    2014-12-01

    The near-surface mineralogy of terrestrial planets and moons, and the corresponding evolution of habitable environments, is shaped by physical, chemical, and biological processes. Four factors contribute to a planet's mineral distribution and diversity: (1) planetary stoichiometry; (2) crystal chemical characteristics; (3) mineral stability ranges; and (4) the probability of occurrence for rare minerals. Measurements of stellar stoichiometry reveal that stars can differ significantly from the Sun in relative abundances of rock-forming elements, which implies that bulk compositions of some extrasolar Earth-like planets differ significantly from those of Earth, particularly if fractionation processes in evolving stellar nebulas and planetary differentiation are factored in. Comparison of Earth's upper continental crust and the Moon shows that differences in element ratios are reflected in ratios of mineral species containing these elements. More abundant elements generally have larger numbers of mineral species, though elements that mimic other more abundant elements are less likely to form their own species. Total mineral diversity for different elements is not appreciably influenced by the relative stabilities of individual phases, e.g., the broad pressure-temperature-composition stability range of zircon (ZrSiO4) does not significantly diminish the total number of observed Zr minerals. To the extent that origins and evolution of life depend on key mineral species, habitability is dependent on the emergence of a minimal mineral diversity. Evolving life has, in turn, exerted the largest single influence on mineral diversity. Notably, changes in near-surface redox conditions on Earth through the evolution of oxygenic photosynthesis tripled the available "composition space" of Earth's near-surface environment, and resulted in a corresponding tripling of mineral diversity subsequent to atmospheric oxidation. Statistical analysis of mineral frequency distributions

  16. Solar nebula magnetic fields recorded in the Semarkona meteorite

    DEFF Research Database (Denmark)

    Fu, Roger R.; Weiss, Benjamin P.; Lima, Eduardo A.

    2014-01-01

    Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the first solids. However, there have been no experimental constraints on the int...

  17. Visualization of Kepler's Laws of Planetary Motion

    Science.gov (United States)

    Lu, Meishu; Su, Jun; Wang, Weiguo; Lu, Jianlong

    2017-01-01

    For this article, we use a 3D printer to print a surface similar to universal gravitation for demonstrating and investigating Kepler's laws of planetary motion describing the motion of a small ball on the surface. This novel experimental method allows Kepler's laws of planetary motion to be visualized and will contribute to improving the…

  18. Preparing Planetary Scientists to Engage Audiences

    Science.gov (United States)

    Shupla, C. B.; Shaner, A. J.; Hackler, A. S.

    2017-12-01

    While some planetary scientists have extensive experience sharing their science with audiences, many can benefit from guidance on giving presentations or conducting activities for students. The Lunar and Planetary Institute (LPI) provides resources and trainings to support planetary scientists in their communication efforts. Trainings have included sessions for students and early career scientists at conferences (providing opportunities for them to practice their delivery and receive feedback for their poster and oral presentations), as well as separate communication workshops on how to engage various audiences. LPI has similarly begun coaching planetary scientists to help them prepare their public presentations. LPI is also helping to connect different audiences and their requests for speakers to planetary scientists. Scientists have been key contributors in developing and conducting activities in LPI education and public events. LPI is currently working with scientists to identify and redesign short planetary science activities for scientists to use with different audiences. The activities will be tied to fundamental planetary science concepts, with basic materials and simple modifications to engage different ages and audience size and background. Input from the planetary science community on these efforts is welcome. Current results and resources, as well as future opportunities will be shared.

  19. Introduction to the special issue: Planetary geomorphology

    Science.gov (United States)

    Burr, Devon M.; Howard, Alan D.

    2015-07-01

    Planetary geomorphology is the study of extraterrestrial landscapes. In recognition of the promise for productive interaction between terrestrial and planetary geomorphologists, the 45th annual Binghamton Geomorphology Symposium (BGS) focused on Planetary Geomorphology. The aim of the symposium was to bring planetary and terrestrial geomorphologists together for symbiotic and synthetic interactions that would enrich both subdisciplines. In acknowledgment of the crucial role of terrestrial field work in planetary geomorphology and of the BGS tradition, the symposium began with a field trip to the Appalachian Mountains, followed by a dinner talk of recent results from the Mars Surface Laboratory. On Saturday and Sunday, the symposium was organized around major themes in planetary geomorphology, starting with the geomorphic processes that are most common in our Solar System-impact cratering, tectonism, volcanism-to set the stage for other geomorphic processes, including aeolian, fluvial, lacustrine, and glacial/polar. On Saturday evening, the banquet talk provided an historical overview of planetary geomorphology, including its roots in the terrestrial geosciences. The symposium concluded with a full-afternoon tutorial on planetary geomorphologic datasets. This special issue of Geomorphology consists of papers by invited authors from the 2014 BGS, and this introduction provides some context for these papers.

  20. Interoperability in the Planetary Science Archive (PSA)

    Science.gov (United States)

    Rios Diaz, C.

    2017-09-01

    The protocols and standards currently being supported by the recently released new version of the Planetary Science Archive at this time are the Planetary Data Access Protocol (PDAP), the EuroPlanet- Table Access Protocol (EPN-TAP) and Open Geospatial Consortium (OGC) standards. We explore these protocols in more detail providing scientifically useful examples of their usage within the PSA.

  1. Planetary CubeSats Come of Age

    Science.gov (United States)

    Sherwood, Brent; Spangelo, Sara; Frick, Andreas; Castillo-Rogez, Julie; Klesh, Andrew; Wyatt, E. Jay; Reh, Kim; Baker, John

    2015-01-01

    Jet Propulsion Laboratory initiatives in developing and formulating planetary CubeSats are described. Six flight systems already complete or underway now at JPL for missions to interplanetary space, the Moon, a near-Earth asteroid, and Mars are described at the subsystem level. Key differences between interplanetary nanospacecraft and LEO CubeSats are explained, as well as JPL's adaptation of vendor components and development of system solutions to meet planetary-mission needs. Feasible technology-demonstration and science measurement objectives are described for multiple modes of planetary mission implementation. Seven planetary-science demonstration mission concepts, already proposed to NASA by Discovery-2014 PIs partnered with JPL, are described for investigations at Sun-Earth L5, Venus, NEA 1999 FG3, comet Tempel 2, Phobos, main-belt asteroid 24 Themis, and metal asteroid 16 Psyche. The JPL staff and facilities resources available to PIs for analysis, design, and development of planetary nanospacecraft are catalogued.

  2. The Light and Dark Face of a Star-Forming Nebula

    Science.gov (United States)

    2010-03-01

    Today, ESO is unveiling an image of the little known Gum 19, a faint nebula that, in the infrared, appears dark on one half and bright on the other. On one side hot hydrogen gas is illuminated by a supergiant blue star called V391 Velorum. New star formation is taking place within the ribbon of luminous and dark material that brackets V391 Velorum's left in this perspective. After many millennia, these fledgling stars, coupled with the explosive demise of V391 Velorum as a supernova, will likely alter Gum 19's present Janus-like appearance. Gum 19 is located in the direction of the constellation Vela (the Sail) at a distance of approximately 22 000 light years. The Gum 19 moniker derives from a 1955 publication by the Australian astrophysicist Colin S. Gum that served as the first significant survey of so-called HII (read "H-two") regions in the southern sky. HII refers to hydrogen gas that is ionised, or energised to the extent that the hydrogen atoms lose their electrons. Such regions emit light at well-defined wavelengths (or colours), thereby giving these cosmic clouds their characteristic glow. And indeed, much like terrestrial clouds, the shapes and textures of these HII regions change as time passes, though over the course of eons rather than before our eyes. For now, Gum 19 has somewhat of a science fiction-esque, "rip in spacetime" look to it in this image, with a narrow, near-vertical bright region slashing across the nebula. Looking at it, you could possibly see a resemblance to a two-toned angelfish or an arrow with a darkened point. This new image of the evocative Gum 19 object was captured by an infrared instrument called SOFI, mounted on ESO's New Technology Telescope (NTT) that operates at the La Silla Observatory in Chile. SOFI stands for Son of ISAAC, after the "father" instrument, ISAAC, that is located at ESO's Very Large Telescope observatory at Paranal to the north of La Silla. Observing this nebula in the infrared allows astronomers to see

  3. Spectroscopic Binaries in the Orion Nebula Cluster and NGC 2264

    Science.gov (United States)

    Kounkel, Marina; Hartmann, Lee; Tobin, John J.; Mateo, Mario; Bailey, John I., III; Spencer, Meghin

    2016-04-01

    We examine the spectroscopic binary population for two massive nearby regions of clustered star formation, the Orion Nebula Cluster (ONC) and NGC 2264, supplementing the data presented by Tobin et al. with more recent observations and more extensive analysis. The inferred multiplicity fraction up to 10 au based on these observations is 5.3 ± 1.2% for NGC 2264 and 5.8 ± 1.1% for the ONC; these values are consistent with the distribution of binaries in the field in the relevant parameter range. Eight of the multiple systems in the sample have enough epochs to perform an initial fit for the orbital parameters. Two of these sources are double-lined spectroscopic binaries; for them, we determine the mass ratio. Our reanalysis of the distribution of stellar radial velocities toward these clusters presents a significantly better agreement between stellar and gas kinematics than was previously thought.

  4. The ultraviolet extinction properties of the 30 Dor Nebula

    Science.gov (United States)

    De Marchi, Guido; Panagia, Nino

    2018-01-01

    Recent investigation of the extinction law in 30 Dor and the Tarantula Nebula, at optical and near infrared wavelengths, has revealed a ratio of total to selective extinction RV=AV/E(B-V) of about 4.5. This indicates a larger proportion of large grains than in the Galactic diffuse interstellar medium. Possible origins include coalescence of small grains, grain growth, selective destruction of small grains, and fresh injection of large grains. From a study of the ultraviolet extinction properties of three Wolf-Rayet stars in 30 Dor (R 139, R 140, R 145), observed with the International Ultraviolet Explorer, we show that the excess of large grains does not come at the expense of small grains, which are still present. Fresh injection of large grains by supernova explosions appears to be the dominant mechanism.

  5. Protoplanetary Nebula Evolution using the Beta Viscosity Model

    Science.gov (United States)

    Davis, Sanford S.

    2003-01-01

    The evolutionary dynamics of a protoplanetary disk is an important component of the planet formation process. In particular, the dynamic and thermodynamic field plays a critical role in chemical evolution, the migration of dust particles in the nebula, and the radial transport of meteoritic components. The dynamic evolution is investigated using analytical solutions of the surface density transport equations using a turbulence model based on hydrodynamic generation of turbulence. It captures the major properties of the disk including region of separation between radial inflow and-outflow and the evolution of the central plane temperature. The analytical formulas are compared with available numerical solutions based on the alpha viscosity model. The beta viscosity model, heretofore used for steady-state disks, is shown to be a useful approximation for unsteady problems.

  6. An earlier explosion date for the Crab Nebula supernova

    Science.gov (United States)

    Abt, Helmut A.; Fountain, John W.

    2018-04-01

    The Chinese first reported the Crab Nebula supernova on 1054 July 5. Ecclesiastical documents from the near east reported it in April and May of 1054. More than 33 petroglyphs made by Native Americans in the US and Mexico are consistent with sightings both before and after conjunction with the Sun on 1054 May 27. We found a petroglyph showing the new star close to Venus and the Moon, which occurred on 1054 April 12 and April 13, respectively. Collins et al., using the four historical dates, derived a light curve that is like that of a Type Ia supernova. The only remaining problem with this identification is that this supernova was near maximum light for 85 d, which is unlike the behavior of any known supernova.

  7. Visualization Tools for Planetary Data

    Science.gov (United States)

    DeWolfe, Alexandria; Larsen, Kristopher; Brain, David; Chaffin, Michael; Harter, Bryan; Putnam, Brian

    2017-04-01

    We have developed a set of software tools for displaying and analyzing data from the MAVEN and MMS missions. In order to better visualize the science data and models, we have constructed 3D visualizations of MAVEN orbiting Mars and MMS orbiting Earth using the CesiumJS library. These visualizations allow viewing of not only spacecraft orientation and position over time, but also scientific data from the spacecraft, and atmospheric models as well. We have also developed a Python toolkit which replicates the functionality of the widely-used IDL "tplot" toolkit for analyzing planetary atmospheric data. We use the bokeh and matplotlib libraries to generate interactive line plots and spectrograms, providing additional functionality beyond the capabilities of IDL graphics. These Python tools are generalized to work with missions beyond MAVEN, and our open-source software is available on Github.

  8. Planetary accretion in circumstellar disks

    Science.gov (United States)

    Lissauer, Jack J.; Stewart, Glen R.

    1993-01-01

    The formation of terrestrial planets and the cores of Jovian planets is reviewed in the framework of the planetesimal hypothesis, wherein planets are assumed to grow via the pairwise accumulation of small solid bodies. Emphasis is placed on the dynamics of solid body accretion from kilometer size planetesimals to terrestrial type planets. This stage of planetary growth is least dependent on the characteristics of the evolutionary state of the central star. It is concluded that the evolution of the planetesimal size distribution is determined by the gravitationally enhanced collision cross-section, which favors collisions between planetesimals with smaller velocities. Runaway growth of the largest planetesimal in each accretion zone appears to be a likely outcome. The subsequent accumulation of the resulting protoplanets leads to a large degree of radial mixing in the terrestrial planet region, and giant impacts are probable.

  9. Sonic anemometry of planetary atmospheres

    Science.gov (United States)

    Cuerva, Alvaro; Sanz-Andrés, Angel; Lorenz, Ralph D.

    2004-02-01

    Sonic anemometers are robust, fast and reliable wind sensors which are able to measure the complete wind speed vector at high sampling rates. All these characteristics make sonic anemometers to be ideal candidates for atmospheric applications. Since sonic anemometers have not moving parts and they can be designed to have loss mass and power consumption, they have become adequate for planetary exploration purposes, both for atmosphere studies and for flying robot control. However, some challenges must be undertaken before implementing their use. Problems such as sound attenuation in different atmospheres, sensor/air acoustic impedance matching as well as flow/fluid dependence of sonic measurements have to be considered when these sensors are used in other atmospheres.

  10. Synthesis of Organics in the Early Solar Nebula

    Science.gov (United States)

    Johnson, Natasha M.; Manning, S.; Nuth, J. A., III

    2007-10-01

    It is unknown what process or processes made the organics that are found or detected in extraterrestrial materials. One process that forms organics are Fischer-Tropsch type (FTT) reactions. Fischer-Tropsch type synthesis produces complex hydrocarbons by hydrogenating carbon monoxide via surface mediated reactions. The products of these reactions have been well-studied using `natural’ catalysts [1] and calculations of the efficiency of FTT synthesis in the Solar Nebula suggest that these types of reactions could make significant contributions to material near three AU [2]. We use FTT synthesis to coat Fe-silicate amorphous grains with organic material to simulate the chemistry in the early Solar Nebula. These coatings are composed of macromolecular organic phases [3]. Previous work also showed that as the grains became coated, Haber-Bosch type reactions took place resulting in nitrogen-bearing organics [4]. Our experiments consist of circulating CO, N2, and H2 gas through Fe- amorphous silicate grains that are maintained at a specific temperature in a closed system. The gases are passed through an FTIR spectrometer and are measured to monitor the reaction progress. Samples are analyzed using FTIR, and GCMS (including pyrolysis) and extraction techniques are used to analyze the organic coatings. These experiments show that these types of reactions are an effective means to produce complex hydrocarbons. We present the analysis of the produced organics (solid and gas phase) and the change in the production rate of several compounds as the grains become coated. Organics generated by this technique could represent the carbonaceous material incorporated in comets and meteorites. References: [1] Hayatsu and Anders 1981. Topics in Current Chemistry 99:1-37. [2] Kress and Tielens 2001. MAPS 36:75-91. [3] Johnson et al. 2004. #1876. 35th LPSC. [4] Hill and Nuth 2003. Astrobiology 3:291-304. This work was supported by a grant from NASA.

  11. New View of Gas and Dust in the Solar Nebula

    Science.gov (United States)

    Taylor, G. J.

    2010-08-01

    The recognizable components in meteorites differ in their relative abundances of the three oxygen isotopes (16O, 17O, and 18O). In particular, the amount of 16O varies from being like that of the Earth to substantially enriched compared to the other two isotopes. The current explanation for this interesting range in isotopic composition is that dust and gas in the solar nebula (the cloud of gas and dust surrounding the primitive Sun) began with the same 16O-rich composition, but the solids evolved towards the terrestrial value. A new analysis of the problem by Alexander Krot (University of Hawaii) and colleagues at the University of Hawaii, the University of Chicago, Clemson University, and Lawrence Livermore National Laboratory leads to the bold assertion that primordial dust and gas differed in isotopic composition. The gas was rich in 16O as previously thought (possibly slightly richer in 16O than the measurements of the solar wind returned by the Genesis Mission), but that the dust had a composition close to the 16O-depleted terrestrial average. In this new view, the dust had a different history than did the gas before being incorporated into the Solar System. Solids with compositions near the terrestrial line may have formed in regions of the solar nebula where dust had concentrated compared to the mean solar dust/gas ratio (1 : ~100). The idea has great implications for understanding the oxygen-isotope composition of the inner Solar System and the origin of materials in the molecular cloud from which the Solar System formed.

  12. Hot Gas in the Wolf–Rayet Nebula NGC 3199

    Energy Technology Data Exchange (ETDEWEB)

    Toalá, J. A.; Chu, Y.-H. [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), Taipei 10617, Taiwan (China); Marston, A. P. [European Space Agency/STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Guerrero, M. A. [Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, Granada E-18008 (Spain); Gruendl, R. A. [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States)

    2017-09-01

    The Wolf–Rayet (WR) nebula NGC 3199 has been suggested to be a bow shock around its central star, WR 18, which is presumably a runaway star, because optical images of the nebula show a dominating arc of emission southwest of the star. We present the XMM-Newton detection of extended X-ray emission from NGC 3199, unveiling the powerful effect of the fast wind from WR 18. The X-ray emission is brighter in the region southeast of the star and an analysis of the spectral properties of the X-ray emission reveals abundance variations: (i) regions close to the optical arc present nitrogen-rich gas enhanced by the stellar wind from WR 18 and (ii) gas at the eastern region exhibits abundances close to those reported for the nebular abundances derived from optical studies, which is a signature of an efficient mixing of the nebular material with the stellar wind. The dominant plasma temperature and electron density are estimated to be T ≈ 1.2 × 10{sup 6} K and n {sub e} = 0.3 cm{sup −3} with an X-ray luminosity in the 0.3–3.0 keV energy range of L {sub X} = 2.6 × 10{sup 34} erg s{sup −1}. Combined with information derived from Herschel and the recent Gaia first data release, we conclude that WR 18 is not a runaway star and that the formation, chemical variations, and the shape of NGC 3199 depend on the initial configuration of the interstellar medium.

  13. Cloud structure and feedback effects in the Carina Nebula Complex

    Science.gov (United States)

    Roccatagliata, Veronica; Preibisch, Thomas; Gaczkowski, Benjamin; Ratzka, Thorsten

    2013-07-01

    The star formation process in large clusters/associations can be strongly influenced by the feedback from high mass stars. Whether the resulting net effect of the feedback is predominantly negative (cloud dispersal) or positive (triggering of star formation due to cloud compression) is still an open question. The Carina Nebula complex (CNC) represents one of the most massive star-forming regions in our Galaxy. We use our Herschel far-infrared observations to study the properties of the clouds over the entire CNC and LABOCA/APEX telescope on the central part of the CNC.Our Herschel maps resolve, for the first time, the small-scale structure of the dense clouds over the entire spatial extent of the CNC. Several particularly interesting regions, including the prominent pillars south of eta Car, are analyzed in detail. Our maps also reveal a peculiar 'wave'-like pattern in the northern part of the Carina Nebula. The total mass of the clouds seen by Herschel in the central region is about 656 000 Msun. We derive the global spectral energy distribution in the mid-infrared to mm wavelength range and derive a total mass of stars, rather than random turbulence. Comparing the cloud mass and the star formation rate derived for the CNC to other Galactic star forming regions suggests that the CNC is forming stars very efficiently. We suggest this to be a consequence of triggered star formation by radiative cloud compression.In our LABOCA sub-mm map, we identify about 600 individual clumps. We analyze and interpret the clump initial mass function (CIMF) as signature of turbulent pre-stellar clouds or star-forming clouds.

  14. The International Planetary Data Alliance

    Science.gov (United States)

    Stein, T.; Arviset, C.; Crichton, D. J.

    2017-12-01

    The International Planetary Data Alliance (IPDA) is an association of partners with the aim of improving the quality of planetary science data and services to the end users of space based instrumentation. The specific mission of the IPDA is to facilitate global access to, and exchange of, high quality scientific data products managed across international boundaries. Ensuring proper capture, accessibility and availability of the data is the task of the individual member space agencies. The IPDA was formed in 2006 with the purpose of adopting standards and developing collaborations across agencies to ensure data is captured in common formats. Member agencies include: Armenian Astronomical Society, China National Space Agency (CNSA), European Space Agency (ESA), German Aerospace Center (DLR), Indian Space Research Organization (ISRO), Italian Space Agency (ASI), Japanese Aerospace Exploration Agency (JAXA), National Air and Space Administration (NASA), National Centre for Space Studies (CNES), Space Research Institute (IKI), UAE Space Agency, and UK Space Agency. The IPDA Steering Committee oversees the execution of projects and coordinates international collaboration. The IPDA conducts a number of focused projects to enable interoperability, construction of compatible archives, and the operation of the IPDA as a whole. These projects have helped to establish the IPDA and to move the collaboration forward. A key project that is currently underway is the implementation of the PDS4 data standard. Given the international focus, it has been critical that the PDS and the IPDA collaborate on its development. Also, other projects have been conducted successfully, including developing the IPDA architecture and corresponding requirements, developing shared registries for data and tools across international boundaries, and common templates for supporting agreements for archiving and sharing data for international missions. Several projects demonstrating interoperability across

  15. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    Science.gov (United States)

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium.

  16. Colorimetry of the diffuse nebulas S 156, S 157A, S 158, and NGC 7635

    Energy Technology Data Exchange (ETDEWEB)

    Parsamian, E.S.; Petrosian, V.M.

    1984-11-01

    The results of a colorimetric investigation of the diffuse nebulas S 156, S 157A, S 158, and NGC 7635, which are excited by O stars, are presented. The nebulas S 156, S 157A, and NGC 7635 are very bright in U due to the presence in them of strong ultraviolet doublet forbidden O II 3727 A. These values correspond effectively to the monochromatic image of the nebulas at this wavelength. The measurements show that the B-V color index does not change significantly with distance from the star except for S 158, where a weak dependence is observed. The results indicate that the physical properties of these nebulas differ little. It is concluded that the gas masses in this association are remnants of star formation that have a common origin with the stars. The age of the association is estimated at 100,000-1,000,000 yr. 13 references.

  17. Planetary gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Reedy, R.C.

    1978-01-01

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed

  18. IRAS surface brightness maps of visible reflection nebulae: evidence for non-equilibrium infrared emission

    International Nuclear Information System (INIS)

    Castelaz, M.W.; Werner, M.W.; Sellgren, K.

    1986-01-01

    Surface brightness maps at 12, 25, 60, and 100 microns of 16 visible reflection nebulae were extracted from the Infrared Astronomy Satellite (IRAS) database. The maps were produced by coadding IRAS survey scans over areas centered on the illuminating stars, and have spatial resolutions of 0.9' x 4' at 12 and 25 microns, 1.8' x 4.5' at 60 microns, and 3.6' x 5' at 100 microns. Extended emission in the four IRAS bandpasses was detected in fourteen of the reflection nebulae. The IRAS data were used to measure the flux of the infrared emission associated with each source. The energy distributions show that the 12 micron flux is greater than the 25 micron flux in 11 of the nebulae, and the peak flux occurs in the 60 or 100 micron bandpass in all 16 nebular. The 60 and 100 micron flux can be approximated by blackbodies with temperatures between 30 and 50 K, consistent with temperatures expected from extrapolation of greybody fits to the 60 and 100 micron data. The excess 12 and 25 micron emission is attributed to a nonequilibrium process such as emission from thermal fluctuations of very small grains excited by single ultraviolet photons, or emission from polycyclic aromatic hydrocarbons (PAHs) excited by ultraviolet radiation. The common features of the energy distributions of the 16 reflection nebulae, also seen in the reflection nebulae associated with the Pleiades, suggest that PAHs or very small grains may be found in most reflection nebulae

  19. A ROTATIONALLY POWERED MAGNETAR NEBULA AROUND SWIFT J1834.9–0846

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Diego F. [Institute of Space Sciences (IEEC-CSIC), Campus UAB, Carrer de Magrans s/n, E-08193 Barcelona (Spain)

    2017-01-20

    A wind nebula generating extended X-ray emission was recently detected surrounding Swift J1834.9–0846. This is the first magnetar for which such a wind nebula was found. Here, we investigate whether there is a plausible scenario where the pulsar wind nebula (PWN) can be sustained without the need of advocating for additional sources of energy other than rotational. We do this by using a detailed radiative and dynamical code that studies the evolution of the nebula and its particle population in time. We find that such a scenario indeed exists: Swift J1834.9–0846's nebula can be explained as being rotationally powered, as all other known PWNe are, if it is currently being compressed by the environment. The latter introduces several effects, the most important of which is the appearance of adiabatic heating, being increasingly dominant over the escape of particles as reverberation goes by. The need of reverberation naturally explains why this is the only magnetar nebula detected and provides estimates for Swift 1834.9–0846's age.

  20. An online planetary exploration tool: ;Country Movers;

    Science.gov (United States)

    Gede, Mátyás; Hargitai, Henrik

    2017-08-01

    Results in astrogeologic investigations are rarely communicated towards the general public by maps despite the new advances in planetary spatial informatics and new spatial datasets in high resolution and more complete coverage. Planetary maps are typically produced by astrogeologists for other professionals, and not by cartographers for the general public. We report on an application designed for students, which uses cartography as framework to aid the virtual exploration of other planets and moons, using the concepts of size comparison and travel time calculation. We also describe educational activities that build on geographic knowledge and expand it to planetary surfaces.