WorldWideScience

Sample records for ae supergiant hd

  1. Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra

    Science.gov (United States)

    Tanrıverdi, T.; Baştürk, Ö.

    2016-08-01

    This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD 80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003)1

  2. HD 133656 : A new high-latitude supergiant

    NARCIS (Netherlands)

    VanWinckel, H; Oudmaijer, RD; Trams, NR

    1996-01-01

    In the course of our study of post-asymptotic Giant Branch objects, we discovered that the seventh magnitude A supergiant HD 133656 has an infrared excess emission due to cool circumstellar dust, and that its photospheric abundance pattern is population II like. We present a detailed abundance study

  3. Ultraviolet analysis of the peculiar supergiant HD 112374 = HR 4912

    Science.gov (United States)

    Bohm-Vitense, E.; Proffitt, C.

    1984-01-01

    The ultraviolet energy distribution of the metal-poor supergiant HD 112374 is analyzed based on observations from the International Ultraviolet Explorer (IUE) satellite for the region between 1200 and 2000 A. A discontinuity was found in the UV spectra at 2600 A which confirmed the low-abundance of heavy elements found by Luck et al. (1983). Values for effective temperature and log g in HD112374 were consistent with the star being a very luminous Population II semi-regular variable. The full observational results are presented in a table.

  4. Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra

    CERN Document Server

    Tanrıverdi, Taner

    2015-01-01

    This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003) were analysed to compute their elemental abundances using ATLAS9 (Kurucz, 1993, 2005; Sbordone et al., 2004). In our analysis we assumed local thermodynamic equilibrium. The atmospheric parameters of HD 80057 used in this study are from Firnstein & Przybilla (2012), and that of HD80404 are derived from spectral energy distribution, ionization equilibria of Cr I/II and Fe I/II, and the fits to the wings of Balmer lines and Paschen lines as Teff = 7700 +/- 150 K and log g=1.60 +/- 0.15 (in cgs). The microturbulent velocities of HD 80057 and HD 80404 have been determined as 4.3 +/- 0.1 and 2.2 +/- 0.7 km s^-1 . The rotational velocities are 15 +/-1 and 7 +/- 2 km s^-1 and their macroturbulence velocities are 24 +/-2 and 2+/-1 km s^-1 . We have given the abundances...

  5. The Herbig Ae Star HD 163296 in X-Rays

    Science.gov (United States)

    Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward

    2004-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT approximately 0.5 approximately kev), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least approximately 100 approximately G and perhaps as high as several kG.

  6. The Herbig Ae star HD 163296 in X-rays

    CERN Document Server

    Swartz, D A; Elsner, R F; Ghosh, K K; Grady, C A; Wassell, E; Woodgate, B E; Kimble, R A; Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward; Woodgate, Bruce E.; Kimble, Randy A.

    2005-01-01

    Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT~0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion.

  7. HD 187885 and s-process elements in high galactic latitude supergiants

    NARCIS (Netherlands)

    VanWinckel, H; Waelkens, C; Waters, LBFM

    1996-01-01

    We present an accurate LTE chemical analysis of HD 187885 on the basis of high-resolution, high signal-to-noise spectra. The low iron abundance of [Fe/H] = -0.5 confirms the old, low-mass nature of the supergiant. With [C/Fe] = +0.9, [N/Fe] = +0.7, [O/Fe] = +0.6 and above all the high s-process elem

  8. Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569

    NARCIS (Netherlands)

    Merin, B; Montesinos, B; Eiroa, C; Solano, E; Mora, A; D'Alessio, P; Calvet, N; Oudmaijer, RD; de Winter, D; Davies, JK; Harris, AW; Cameron, A; Deeg, HJ; Ferlet, R; Garzon, F; Grady, CA; Horne, K; Miranda, LF; Palacios, J; Penny, A; Quirrenbach, A; Rauer, H; Schneider, J; Wesselius, PR

    2004-01-01

    We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of HD 34282 and HD 141569, two pre-main sequence Herbig AeBe stars. Both objects have been reported to show "anomalous positions" in the HR diagram in the sense that they appear below the main sequence.

  9. The eccentric short-period orbit of the supergiant fast X-ray transient HD 74194 (=LM Vel)

    CERN Document Server

    Gamen, R; Walborn, N R; Morrell, N I; Arias, J I; Apellániz, J Maíz; Sota, A; Alfaro, E J

    2015-01-01

    Aims. We present the first orbital solution for the O-type supergiant star HD 74194, which is the optical counterpart of the supergiant fast X-ray transient IGR J08408-4503. Methods. We measured the radial velocities in the optical spectrum of HD 74194, and we determined the orbital solution for the first time. We also analysed the complex H{\\alpha} profile. Results. HD 74194 is a binary system composed of an O-type supergiant and a compact object in a short-period ($P=9.5436\\pm0.0002$ d) and high-eccentricity ($e=0.63\\pm0.03$) orbit. The equivalent width of the H{\\alpha} line is not modulated entirely with the orbital period, but seems to vary in a superorbital period ($P=285\\pm10$ d) nearly 30 times longer than the orbital one.

  10. Photometric variability of the Herbig Ae star HD 37806

    CERN Document Server

    Rucinski, S M; Hareter, M; Pojmanski, G; Kuschnig, R; Matthews, J M; Guenther, D B; Moffat, A F J; Sasselov, D; Weiss, W W

    2010-01-01

    The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales ranging between minutes and several years. A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <~0.05 on a time scale of a few years. The resulting variability has properties of stochastic "red" nois...

  11. The Environment of the Optically Brightest Herbig Ae Star, HD 104237

    Science.gov (United States)

    Grady, C. A.; Woodgate, B.; Torres, Carlos A. O.; Henning, Th.; Apai, D.; Rodmann, J.; Wang, Hongchi; Stecklum, B.; Linz, H.; Williger, G. M.; Brown, A.; Wilkinson, E.; Harper, G. M.; Herczeg, G. J.; Danks, A.; Vieira, G. L.; Malumuth, E.; Collins, N. R.; Hill, R. S.

    2004-06-01

    We investigate the environment of the nearest Herbig Ae star, HD 104237, with a multiwavelength combination of optical coronagraphic, near-IR, and mid-IR imaging supported by optical, UV, and far-ultraviolet spectroscopy. We confirm the presence of T Tauri stars associated with the Herbig Ae star HD 104237, noted by Feigelson et al. We find that two of the stars within 15" of HD 104237 have IR excesses, potentially indicating the presence of circumstellar disks, in addition to the Herbig Ae star itself. We derive a new spectral type of A7.5Ve-A8Ve for HD 104237 and find log(L/Lsolar)=1.39. With these data, HD 104237 has an age of t~5 Myr, in agreement with the estimates for the other members of the association. HD 104237 is still actively accreting, with a conspicuous UV/far-UV excess seen down to 1040 Å, and is driving a bipolar microjet termed HH 669. This makes it the second, older Herbig Ae star now known to have a microjet. The presence of the microjet enables us to constrain the circumstellar disk to rExplorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.

  12. HD 179821 (V1427 Aql, IRAS 19114+0002) - a massive post-red supergiant star?

    Science.gov (United States)

    Şahin, T.; Lambert, David L.; Klochkova, Valentina G.; Panchuk, Vladimir E.

    2016-10-01

    We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe] = 1.0 ± 0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H] = 0.4 dex places it among the most metal-rich stars yet analysed. The abundance analysis of this luminous star is based on high-resolution and high-quality (S/N ≈ 120-420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over 21 epochs. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters over all epochs: Teff = 7350 ± 200 K, log g= +0.6 ± 0.3, and a microturbulent velocity ξ = 6.6 ± 1.6 km s-1 and [Fe/H] = 0.4 ± 0.2, and a carbon abundance [C/Fe] = -0.19 ± 0.30. We find oxygen abundance [O/Fe] = -0.25 ± 0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 ± 2.0 km s-1 is determined from both strong and weak Fe I and Fe II lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] ≈ 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for H α line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.

  13. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    OpenAIRE

    Järvinen, S. P.; Hubrig, S.; Schöller, M; Ilyin, I; Carroll, T. A.; Korhonen, H.

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles...

  14. ACCRETION VARIABILITY OF HERBIG Ae/Be STARS OBSERVED BY X-SHOOTER HD 31648 AND HD 163296

    Energy Technology Data Exchange (ETDEWEB)

    Mendigutía, I.; Brittain, S. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States); Eiroa, C.; Meeus, G. [Departamento de Física Teórica, Módulo 15, Facultad de Ciencias, Universidad Autónoma de Madrid, P.O. Box 78, E-28049, Cantoblanco, Madrid (Spain); Montesinos, B. [Centro de Astrobiología, Departamento de Astrofísica (CSIC-INTA), ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Mora, A. [GAIA Science Operations Centre, ESA, European Space Astronomy Centre, P.O. Box 78, E-28691, Villanueva de la Cañada, Madrid (Spain); Muzerolle, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Oudmaijer, R. D. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Rigliaco, E., E-mail: imendig@clemson.edu [Department of Planetary Science, Lunar and Planetary Lab, University of Arizona, 1629, E. University Boulevard, 85719, Tucson, AZ (United States)

    2013-10-10

    This work presents X-Shooter/Very Large Telescope spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of 12 ultraviolet, optical, and near-infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 × 10{sup –7} and 4.50 × 10{sup –7} M{sub ☉} yr{sup –1} for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ∼15 yr. Averaged accretion luminosities derived from the Balmer excess are consistent with the ones inferred from the empirical calibrations with the emission line luminosities, indicating that those can be extrapolated to HAe stars. In spite of that, the accretion rate variations do not generally coincide with those estimated from the line luminosities, suggesting that the empirical calibrations are not useful to accurately quantify accretion rate variability.

  15. Accretion variability of Herbig Ae/Be stars observed by X-Shooter. HD 31648 and HD 163296

    CERN Document Server

    Mendigutía, I; Eiroa, C; Meeus, G; Montesinos, B; Mora, A; Muzerolle, J; Oudmaijer, R D; Rigliaco, E

    2013-01-01

    This work presents X-Shooter/VLT spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of twelve ultraviolet, optical and near infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 x 10^-7 and 4.50 x 10^-7 Msun yr^-1 for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ~ 15 years. Averaged accretion luminosities derived fro...

  16. Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569

    CERN Document Server

    Merin, B; Eiroa, C; Solano, E; Mora, A; D'Alessio, P; Calvet, N

    2004-01-01

    We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of HD 34282 and HD 141569, two pre-main sequence Herbig AeBe stars. Both objects have been reported to show `anomalous positions' in the HR diagram in the sense that they appear below the main sequence. A significant result of this work is that both stars are metal-deficient. The {\\it Hipparcos} distance of HD 34282 is very uncertain and the current study places the star at the expected evolutionary position in the HR diagram, i.e. as a PMS star. The distance for HD 141569 found in this work matches the {\\it Hipparcos} distance, and the problem of its anomalous position is solved as a result of the low metallicity of the object: using the right metallicity tracks, the star is in the PMS region. The SEDs are constructed using data covering ultraviolet to millimetre wavelengths. Physical, non-parametric models, have been applied in order to extract some properties of the disks surrounding the stars. The disk around ...

  17. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999

    Science.gov (United States)

    Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.

    1993-01-01

    Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10(exp -8) solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.

  18. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    CERN Document Server

    Järvinen, S P; Schöller, M; Ilyin, I; Carroll, T A; Korhonen, H

    2016-01-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magn...

  19. Rotationally modulated variations and the mean longitudinal magnetic field of the Herbig Ae star HD 101412

    CERN Document Server

    Hubrig, S; Gonzalez, J F; Schoeller, M; Ilyin, I; Cure, M; Zejda, M; Cowley, C R; Elkin, V G; Pogodin, M A; Yudin, R V

    2010-01-01

    Despite of the importance of magnetic fields for the full understanding of the properties of accreting Herbig Ae/Be stars, these fields have scarcely been studied over the rotation cycle until now. One reason for the paucity of such observations is the lack of knowledge of their rotation periods. The sharp-lined young Herbig Ae star HD101412 with a strong surface magnetic field became in the last years one of the most studied targets among the Herbig Ae/Be stars. A few months ago we obtained multi-epoch polarimetric spectra of this star with FORS2 to search for a rotation period and to constrain the geometry of the magnetic field. We measured longitudinal magnetic fields on 13 different epochs distributed over 62 days. These new measurements together with our previous measurements of the magnetic field in this star were combined with available photometric observations to determine the rotation period. The search of the rotation period resulted in P=42.076+-0.01d. According to near-infrared imaging studies the...

  20. Interplay between pulsations and mass loss in the blue supergiant 55 Cygnus = HD 198478

    CERN Document Server

    Kraus, M; Cidale, L S; Venero, R O J; Nickeler, D H; Nemeth, P; Niemczura, E; Tomic, S; Aret, A; Kubat, J; Kubatova, B; Oksala, M E; Cure, M; Kaminski, K; Dimitrov, W; Fagas, M; Polinska, M

    2015-01-01

    Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested to be linked to stellar pulsations. Pulsational activity in massive stars strongly depends on the star's evolutionary stage and is assumed to be connected with mass-loss episodes, the appearance of macroturbulent line broadening, and the formation of clumps in the wind. To investigate a possible interplay between pulsations and mass-loss, we carried out an observational campaign of the supergiant 55 Cyg over a period of five years to search for photospheric activity and cyclic mass-loss variability in the stellar wind. We modeled the H, He I, Si II and Si III lines using the nonlocal thermal equilibrium atmosphere code FASTWIND and derived the photospheric and wind parameters. In addition, we searched for variability in the intensity and radial velocity of photospheric lines and performed a moment analysis of the line profiles to derive frequencies and amplitudes of the variations. The Halpha line varies wit...

  1. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    Science.gov (United States)

    Järvinen, S. P.; Hubrig, S.; Schöller, M.; Ilyin, I.; Carroll, T. A.; Korhonen, H.

    2016-03-01

    Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magnetic field changes sign from negative to positive polarity. The distribution of field values obtained using Ti, Cr, and Fe lines is, however, completely different compared to the magnetic field values determined in previous low-resolution FORS 2 measurements, where hydrogen Balmer lines are the main contributors to the magnetic field measurements, indicating the presence of concentration of the studied iron-peak elements in the region of the magnetic equator. Further, we discuss the potential role of contamination by the surrounding warm circumstellar matter in the appearance of Zeeman features obtained using Ti lines. Based on data obtained from the ESO Science Archive Facility under request MSCHOELLER 101895 (ESO programme Nos. 081.C-0410(A), 085.C-0137(A), and 187.D-0917(D)).

  2. The magnetic field of the pre-main sequence Herbig Ae star HD 190073

    Science.gov (United States)

    Catala, C.; Alecian, E.; Donati, J.-F.; Wade, G. A.; Landstreet, J. D.; Böhm, T.; Bouret, J.-C.; Bagnulo, S.; Folsom, C.; Silvester, J.

    2007-01-01

    Context: The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. Aims: The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. Methods: We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution, high signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Results: Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74± 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. Conclusions: .This magnetic detection contributes an important new observational discovery which will aid our understanding of stellar magnetism at intermediate masses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  3. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters

    OpenAIRE

    Fumel, Aurelie; Boehm, Torsten

    2011-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigat...

  4. Near-infrared interferometric observation of the Herbig Ae star HD144432 with VLTI/AMBER

    CERN Document Server

    Chen, Lei; Wang, Yang; Weigelt, Gerd; Hofmann, Karl-Heinz; Kraus, Stefan; Schertl, Dieter; Lagarde, Stephane; Natta, Antonella; Petrov, Roman; Robbe-Dubois, Sylvie; Tatulli, Eric

    2012-01-01

    We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the structure of its inner dust disk. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H- and K-band visibilities, the near- and mid-infrared visibilities from the literature, and the SED of HD144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. We derived a K-band ring-fit radius of 0.17 \\pm 0.01 AU and an H-band radius of 0.18 \\pm 0.01 AU (for a distance of 145 pc). This measured K-band radius of \\sim0.17 AU lies in the range between the dust sublimation radius of \\sim0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (\\sim0.27 AU). We found that an additional extended halo component is required in both the geometric and temperature-gradi...

  5. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    CERN Document Server

    Ellerbroek, L E; Dougados, C; Cabrit, S; Sitko, M L; Sana, H; Kaper, L; de Koter, A; Klaassen, P D; Mulders, G D; Mendigutia, I; Grady, C A; Grankin, K; van Winckel, H; Bacciotti, F; Russell, R W; Lynch, D K; Hammel, H B; Beerman, L C; Day, A N; Huelsman, D M; Werren, C; Henden, A; Grindlay, J

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination...

  6. The circumstellar disc around the Herbig AeBe star HD169142

    CERN Document Server

    Dent, W R F; Osorio, M; Calvet, N; Anglada, G

    2006-01-01

    We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy), unresolved (~1") 7 mm continuum emission, being one of the brightest isolated Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm wavelength range, indicating that the observed flux density at 7mm is most likely dominated by thermal dust emission coming from a circumstellar disc. We use available photometric data from the literature to model the spectral energy distribution (SED) of this object from radio to near-ultraviolet frequencies. The observed SED can be understood in terms of an irradiated accretion disc with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star with an age of ~10 Myr....

  7. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD101412

    CERN Document Server

    Schöller, M; Cahuasqui, J A; Drake, N A; Hubrig, S; Petr-Gotzens, M G; Savanov, I S; Wolff, B; Gonzalez, J F; Mysore, S; Ilyin, I; Jarvinen, S P; Stelzer, B

    2016-01-01

    Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD101412. We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He I lambda 10,830 and Pa gamma lines, formed in the accretion region. We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD101412 can be explained by rotational modulation of line profiles generated by accreting gas with a pe...

  8. The compact H$\\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry

    CERN Document Server

    Mendigutía, I; Mourard, D; Muzerolle, J

    2016-01-01

    This work presents CHARA/VEGA H$\\alpha$ spectro-interferometry (R ~ 6000, and $\\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The observed H$\\alpha$ emission is spatially unresolved, indicating that the size of the H$\\alpha$ emitting region is smaller than ~ 0.21 and 0.12 au for HD 179218 and HD 141529 (~ 15 and 16 R*, respectively). This is smaller than for the two other HAeBes previously observed with the same instrumentation. Two different scenarios have been explored in order to explain the compact line emitting regions. A hot, several thousand K, blackbody disc is consistent with the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is able to reproduce the bulk of the H$\\alpha$ emission shown by HD 179218, confirming previous estimates from MA shock modelling with a mass accretion rate of 10^-8 Msun/yr, and an inclination to the line of sight between 30 and 50 degr. The H$\\al...

  9. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD 101412

    Science.gov (United States)

    Schöller, M.; Pogodin, M. A.; Cahuasquí, J. A.; Drake, N. A.; Hubrig, S.; Petr-Gotzens, M. G.; Savanov, I. S.; Wolff, B.; González, J. F.; Mysore, S.; Ilyin, I.; Järvinen, S. P.; Stelzer, B.

    2016-07-01

    Context. Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. Aims: We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD 101412. Methods: We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD 101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD 101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He iλ10 830 and Paγ lines, formed in the accretion region. Results: We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD 101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d±1.68d. The discovery of this period, about half of the magnetic rotation period Pm = 42.076d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 087.C-0124(A), 088.C-0218(A,B,C,E), 090.C-0331(A), and 092.C-0126(A).

  10. HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star?

    CERN Document Server

    Sahin, Timur; Klochkova, Valentina G; Panchuk, Vladimir E

    2016-01-01

    We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0$\\pm$0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich stars yet analyzed. The abundance analysis of this luminous star is based on high resolution and high quality (S/N$\\approx$120--420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over twenty-one epochs. Standard 1D {\\sc LTE} analysis provides a fresh determination of the atmospheric parameters over all epochs: \\Teff = 7350$\\pm$200 \\kelvin, \\logg = +0.6$\\pm$0.3, and a microturbulent velocity $\\xi =$ 6.6$\\pm$1.6 km s$^{\\rm -1}$ and [Fe/H] = 0.4$\\pm$0.2, and a carbon abundance [C/Fe]= $-$0.19$\\pm$0.30. We find oxygen abundance [O/Fe]= $-$0.25$\\pm$0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 $\\pm$ 2.0 km s$^{\\rm -1}$ is determined from both strong and we...

  11. The B-Supergiant Components of the Double-Lined Binary HD1383

    CERN Document Server

    Boyajian, T S; Helsel, M E; Kaye, A B; McSwain, M V; Riddle, R L; Wingert, D W

    2006-01-01

    We present new results from a study of high quality, red spectra of the massive binary star system HD 1383 (B0.5 Ib + B0.5 Ib). We determined radial velocities and revised orbital elements (P = 20.28184 +/- 0.0002 d) and made Doppler tomographic reconstructions of the component spectra. A comparison of these with model spectra from non-LTE, line blanketed atmospheres indicates that both stars have almost identical masses (M_2/M_1 = 1.020 +/- 0.014), temperatures (T_eff = 28000 +/- 1000 K), gravities (log g = 3.25 +/- 0.25), and projected rotational velocities (V sin i < 30 km/s). We investigate a number of constraints on the radii and masses of the stars based upon the absence of eclipses, surface gravity, stellar wind terminal velocity, and probable location in the Perseus spiral arm of the Galaxy, and these indicate a range in probable radius and mass of R/R_sun = 14 - 20 and M/M_sun = 16 - 35, respectively. These values are consistent with model evolutionary masses for single stars of this temperature a...

  12. Low-amplitude rotational modulation rather than pulsations in the CoRoT B-type supergiant HD 46769

    Science.gov (United States)

    Aerts, C.; Simón-Díaz, S.; Catala, C.; Neiner, C.; Briquet, M.; Castro, N.; Schmid, V. S.; Scardia, M.; Rainer, M.; Poretti, E.; Pápics, P. I.; Degroote, P.; Bloemen, S.; Østensen, R. H.; Auvergne, M.; Baglin, A.; Baudin, F.; Michel, E.; Samadi, R.

    2013-09-01

    Aims: We aim to detect and interpret photometric and spectroscopic variability of the bright CoRoT B-type supergiant target HD 46769 (V = 5.79). We also attempt to detect a magnetic field in the target. Methods: We analyse a 23-day oversampled CoRoT light curve after detrending and spectroscopic follow-up data using standard Fourier analysis and phase dispersion minimization methods. We determine the fundamental parameters of the star, as well as its abundances from the most prominent spectral lines. We perform a Monte Carlo analysis of spectropolarimetric data to obtain an upper limit of the polar magnetic field, assuming a dipole field. Results: In the CoRoT data, we detect a dominant period of 4.84 d with an amplitude of 87 ppm and some of its (sub-)multiples. Given the shape of the phase-folded light curve and the absence of binary motion, we interpret the dominant variability in terms of rotational modulation, with a rotation period of 9.69 d. Subtraction of the rotational modulation signal does not reveal any sign of pulsations. Our results are consistent with the absence of variability in the Hipparcos light curve. The spectroscopy leads to a projected rotational velocity of 72 ± 2 km s-1 and does not reveal periodic variability or the need to invoke macroturbulent line broadening. No signature of a magnetic field is detected in our data. A field stronger than ~500 G at the poles can be excluded, unless the possible non-detected field were more complex than dipolar. Conclusions: The absence of pulsations and macroturbulence of this evolved B-type supergiant is placed into the context of instability computations and of observed variability of evolved B-type stars. Based on CoRoT space-based photometric data; the CoRoT space mission was developed and operated by the French space agency CNES, with the participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. Based on observations collected at La Silla Observatory, ESO

  13. Variability of Disk Emission in Pre-main-sequence and Related Stars. I. HD 31648 and HD 163296: Isolated Herbig Ae Stars Driving Herbig-Haro Flows

    Science.gov (United States)

    Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Wilde, J. Leon; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venterini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, R. Brad

    2008-01-01

    Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 micron in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 micron region throughout this span of time. In both stars, the changes in the 1-5 micron flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly simultaneous photometric data.

  14. Variability of Disk Emission in Pre-Main Sequence and Related Stars. I. HD 31648 and HD 163296 - Isolated Herbig Ae Stars Driving Herbig-Haro Flows

    Science.gov (United States)

    Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venturini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, Raleigh B.

    2007-01-01

    Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 pm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 pm region throughout this span of time. In both stars the changes in the 1-5 pm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly-simultaneous photometric data.

  15. VLTI/AMBER spectro-interferometry of the late-type supergiants V766 Cen (=HR 5171 A), sigma Oph, BM Sco, and HD 206859

    CERN Document Server

    Wittkowski, M; Marcaide, J M; Abellan, F J; Chiavassa, A; Guirado, J C

    2016-01-01

    We add four warmer late-type supergiants to our previous spectro-interferometric studies of red giants and supergiants. V766 Cen (=HR 5171 A) is found to be a high-luminosity log(L/L_sun)=5.8+-0.4 source of Teff 4290+-760 K and radius 1490+-540 Rsun located close to both the Hayashi and Eddington limits; this source is consistent with a 40 Msun evolutionary track without rotation and current mass 27-36 Msun. It exhibits NaI in emission arising from a shell of radius 1.5 Rphot and a photocenter displacement of about 0.1 Rphot. V766 Cen shows strong extended molecular (CO) layers and a dusty circumstellar background component. This suggest an optically thick pseudo-photosphere at about 1.5 Rphot at the onset of the wind. V766 Cen is a red supergiant located close to the Hayashi limit instead of a yellow hypergiant already evolving back toward warmer Teff as previously discussed. The stars sigma Oph, BM Sco, and HD 206859 are found to have lower luminosities of about log(L/Lsun)=3.4-3.5 and Teff of 3900-5300 K, ...

  16. Short time scale spectral variability in the A0 supergiant HD92207 and the importance of line profile variations for the interpretation of FORS2 spectropolarimetric observations

    CERN Document Server

    Hubrig, S; Kholtygin, A F

    2014-01-01

    Our recent search for the presence of a magnetic field in the bright early A-type supergiant HD92207 using FORS2 in spectropolarimetric mode indicated the presence of a longitudinal magnetic field of the order of a few hundred Gauss. Assuming the ideal case of a non-variable star, this discovery has recently been questioned in one work trying to demonstrate the importance of non-photon noise in FORS2 observations. The assumption of non-variability of HD92207 can, however, not be held since substantial profile variations of diverse lines on a time scale of minutes or maybe even a fraction of a minute are detected in FORS2 spectra. The presence of short-term spectral variability in blue supergiants, which are considered as type II supernova progenitors, has not been a subject of systematic studies before and is critical for the current theoretical understanding of their physics. Given the detected short term variability, the question of the presence of a magnetic field cannot be answered without proper modeling...

  17. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters

    CERN Document Server

    Fumel, Aurelie

    2011-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile. To do this, we worked on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present a mode identification corresponding to the detected dominan...

  18. The importance of non-photon noise in stellar spectropolarimetry. The spurious detection of a non-existing magnetic field in the A0 supergiant HD 92207

    CERN Document Server

    Bagnulo, Stefano; Kochukhov, Oleg; Landstreet, John D

    2013-01-01

    The low-resolution, Cassegrain mounted, FORS spectropolarimeter of the ESO Very Large Telescope is being extensively used for magnetic field surveys. Some of the new discoveries suggest that relatively strong magnetic fields may play an important role in numerous physical phenomena observed in the atmospheres as well as in the circumstellar environments of certain kinds of stars. We show in detail how small instabilities or data-reduction inaccuracies represent an alternative explanation for the origin of certain signals of circular polarisation published in recent years. With the help of analytical calculations we simulate the observation of a spectral line in spectropolarimetric mode, adding very small spurious wavelength shifts, which may mimic the effects of seeing variations, rapid variations of the stellar radial velocity, or instrument instabilities. As a case study, we then re-visit the FORS2 measurements that have been used to claim the discovery of a magnetic field in the A0 supergiant HD 92207. In ...

  19. Relating jet structure to photometric variability: the Herbig Ae star HD 163296

    NARCIS (Netherlands)

    L.E. Ellerbroek; L. Podio; C. Dougados; S. Cabrit; M.L. Sitko; H. Sana; L. Kaper; A. de Koter; P.D. Klaassen; G.D. Mulders; I. Mendigutía; C.A. Grady; K. Grankin; H. van Winckel; F. Bacciotti; R.W. Russell; D.K. Lynch; H.B. Hammel; L.C. Beerman; A.N. Day; D.M. Huelsman; C. Werren; A. Henden; J. Grindlay

    2014-01-01

    Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the out

  20. Monte-Carlo radiative transfer simulation of the circumstellar disk of the Herbig Ae star HD 144432

    CERN Document Server

    Chen, L; Weigelt, G; Hofmann, K -H; Schertl, D; Malbet, F; Massi, F; Petrov, R; Stee, Ph

    2015-01-01

    Studies of pre-transitional disks, with a gap region between the inner infrared-emitting region and the outer disk, are important to improving our understanding of disk evolution and planet formation. Previous infrared interferometric observations have shown hints of a gap region in the protoplanetary disk around the Herbig Ae star HD~144432. We study the dust distribution around this star with two-dimensional radiative transfer modeling. We compare the model predictions obtained via the Monte-Carlo radiative transfer code RADMC-3D with infrared interferometric observations and the {\\SED} of HD~144432. The best-fit model that we found consists of an inner optically thin component at $0.21\\enDash0.32~\\AU$ and an optically thick outer disk at $1.4\\enDash10~\\AU$. We also found an alternative model in which the inner sub-AU region consists of an optically thin and an optically thick component. Our modeling suggests an optically thin component exists in the inner sub-AU region, although an optically thick componen...

  1. Gas and dust mass in the disk around the Herbig Ae star HD169142

    CERN Document Server

    Panić, Olja; Wilner, David; Qi, Chunhua

    2008-01-01

    We investigate the physical structure of the gas component of the disk around the pre-main-sequence star HD169142. The 13CO and C18O J=2-1 line emission is observed from the disk with 1.4'' resolution using the Submillimeter Array. We adopt the disk physical structure derived from a model which fits the spectral energy distribution of HD169142. We obtain the full three-dimensional information on the CO emission with the aid of a molecular excitation and radiative transfer code. This information is used for the analysis of our observations and previous 12CO J=2-1 and 1.3 mm continuum data. The disk is in Keplerian rotation and seen at an inclination close to 13 deg from face-on. We conclude that the regions traced by different CO isotopologues are distinct in terms of their vertical location within the disk, their temperature and their column densities. With the given disk structure, we find that freeze-out is not efficient enough to remove a significant amount of CO from gas phase. Both observed lines match t...

  2. Inner disk clearing around the Herbig Ae star HD\\,139614: Evidence for a planet-induced gap ?

    CERN Document Server

    Matter, A; Augereau, J -C; Kluska, J; Crida, A; Carmona, A; Gonzalez, J F; Thi, W F; Bouquin, J -B Le; Olofsson, J; Lopez, B

    2016-01-01

    Spatially resolving the inner dust cavity of the transitional disks is a key to understanding the connection between planetary formation and disk dispersal. The disk around the Herbig star HD 139614 is of particular interest since it presents a pretransitional nature with an au-sized gap, in the dust, that was spatially resolved by mid-IR interferometry. Using new NIR interferometric observations, we aim to characterize the 0.1-10~au region of the HD~139614 disk further and identify viable mechanisms for the inner disk clearing. We report the first multiwavelength radiative transfer modeling of the interferometric data acquired on HD~139614 with PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometries. We confirm a gap structure in the um-sized dust, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing surface density profile, and a depletion of 10^3 relative to the outer disk. Since self-shadowing and photoevaporation appears...

  3. DISCOVERY OF A TWO-ARMED SPIRAL STRUCTURE IN THE GAPPED DISK AROUND HERBIG Ae STAR HD 100453

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Kevin; Apai, Daniel [Department of Astronomy/Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Kasper, Markus [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Robberto, Massimo, E-mail: kwagner@as.arizona.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2015-11-01

    We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (∼42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (∼21–29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ∼850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects.

  4. High-resolution Br-gamma spectro-interferometry of the transitional Herbig Ae/Be star HD 100546: a Keplerian gaseous disc inside the inner rim

    CERN Document Server

    Mendigutía, I; Oudmaijer, R D; Fairlamb, J R; Carciofi, A C; Ilee, J D; Vieira, R G

    2015-01-01

    We present spatially and spectrally resolved Br-gamma emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br-gamma spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2-4 mas and 12000. The Br-gamma visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br-gamma line -displaced 0.6 mas (0.06 au at 100 pc) NE from the star- and that of the K-band continuum emission -displaced 0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br-gamma line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest ...

  5. Chandra X-ray spectroscopy of the very early O supergiant HD 93129A: constraints on wind shocks and the mass-loss rate

    CERN Document Server

    Cohen, David H; Leutenegger, Maurice A; MacArthur, James P; Wollman, Emma E; Sundqvist, Jon O; Fullerton, Alex W; Owocki, Stanley P

    2011-01-01

    We present analysis of both the resolved X-ray emission line profiles and the broadband X-ray spectrum of the O2 If* star HD 93129A, measured with the Chandra HETGS. This star is among the earliest and most massive stars in the Galaxy, and provides a test of the embedded wind shock scenario in a very dense and powerful wind. A major new result is that continuum absorption by the dense wind is the primary cause of the hardness of the observed X-ray spectrum, while intrinsically hard emission from colliding wind shocks contributes less than 10% of the X-ray flux. We find results consistent with the predictions of numerical simulations of the line-driving instability, including line broadening indicating an onset radius of X-ray emission of several tenths Rstar. Helium-like forbidden-to-intercombination line ratios are consistent with this onset radius, and inconsistent with being formed in a wind-collision interface with the star's closest visual companion at a distance of ~100 AU. The broadband X-ray spectrum ...

  6. Chemical abundances for A-and F-type supergiant stars

    CERN Document Server

    Molina, R E

    2016-01-01

    We present the stellar parameters and elemental abundances of a set of A--F-type supergiant stars HD\\,45674, HD\\,180028, HD\\,194951 and HD\\,224893 using high resolution ($R$\\,$\\sim$\\,42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD\\,45674 and HD\\,224893. We reaffirm the abundances for HD\\,180028 and HD\\,194951 studied previously by Luck (2014) respectively. Alpha-elements indicates that objects belong to the thin disc population. From their abundances and its location on the Hertzsprung-Russell diagram seems point out that HD\\,45675, HD\\,194951 and HD\\,224893 are in the post-first dredge-up (post-1DUP) phase and they are moving in the red-blue loop region. HD~180028, on the contary, shows typical abundances of the population I but its evolutionary status could not be satisfactorily defined.

  7. Chemical abundances for A-and F-type supergiant stars

    Science.gov (United States)

    Molina, R. E.; Rivera, H.

    2016-04-01

    We present the stellar parameters and elemental abundances of a set of A-F-type supergiant stars HD 45674, HD 180028, HD 194951 and HD 224893 using high resolution (R≈ 42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD 45674 and HD 224893. We reaffirm the abundances for HD 180028 and HD 194951 studied previously by Luck. Alpha-elements indicate that the objects belong to the thin disc population. Their abundances and their location on the Hertzsprung-Russell diagram seem to indicate that HD 45675, HD 194951 and HD 224893 are in the post-first dredge-up (post-1DUP) phase, and that they are moving in the red-blue loop region. HD 180028, on the contary, shows typical abundances of Population I, but its evolutionary status cannot be satisfactorily defined.

  8. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?

    CERN Document Server

    Carmona, A; Kamp, I; Baruteau, C; Matter, A; Ancker, M van den; Pinte, C; Kóspál, A; Audard, M; Liebhart, A; Sicilia-Aguilar, A; Pinilla, P; Regály, Zs; Güdel, M; Henning, Th; Cieza, L A; Baldovin-Saavedra, C; Meeus, G; Eiroa, C

    2016-01-01

    Context: Quantifying the gas content inside the dust gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the disk of HD 139614, a Herbig Ae star with a transition disk exhibiting a dust gap from 2.3 to 6 AU. Methods: We have obtained ESO/VLT CRIRES high-resolution spectra of CO ro-vibrational emission. We derive disk structure constraints by modeling the line profiles, the spectroastrometric signal, and the rotational diagrams using flat Keplerian disk models. Results: We detected v=1-0 12CO, 2-1 12CO, 1-0 13CO, 1-0 C18O, and 1-0 C17O ro-vibrational lines. 12CO v=1-0 lines have an average width of 14 km/s, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km/s narrower, and are dominated by emission at R>6 AU. The 12CO v=1-0 line profile indicates that if there is a gap in the gas it must be narrower than 2 AU. We find that a drop in the gas surface density (delta_gas)...

  9. AE 941.

    Science.gov (United States)

    2004-01-01

    AE 941 [Arthrovas, Neoretna, Psovascar] is shark cartilage extract that inhibits angiogenesis. AE 941 acts by blocking the two main pathways that contribute to the process of angiogenesis, matrix metalloproteases and the vascular endothelial growth factor signalling pathway. When initial development of AE 941 was being conducted, AEterna assigned the various indications different trademarks. Neovastat was used for oncology, Psovascar was used for dermatology, Neoretna was used for ophthalmology and Arthrovas was used for rheumatology. However, it is unclear if these trademarks will be used in the future and AEterna appears to only be using the Neovastat trademark in its current publications regardless of the indication. AEterna Laboratories signed commercialisation agreements with Grupo Ferrer Internacional SA of Spain and Medac GmbH of Germany in February 2001. Under the terms of the agreement, AEterna has granted exclusive commercialisation and distribution rights to AE 941 in oncology to Grupo Ferrer Internacional for the Southern European countries of France, Belgium, Spain, Greece, Portugal and Italy. It also has rights in Central and South America. Medac GmbH will have marketing rights in Germany, the UK, Scandinavia, Switzerland, Austria, Ireland, the Netherlands and Eastern Europe. In October 2002, AEterna Laboratories announced that it had signed an agreement with Australian healthcare products and services company Mayne Group for marketing AE 941 (as Neovastat) in Australia, New Zealand, Canada and Mexico. In March 2003, AEterna Laboratories announced it has signed an agreement with Korean based LG Life Sciences Ltd for marketing AE 941 (as Neovastat) in South Korea. The agreement provides AEterna with upfront and milestone payments, as well as a return on manufacturing and sales of AE 941. AEterna Laboratories had granted Alcon Laboratories an exclusive worldwide licence for AE 941 for ophthalmic products. However, this licence has been terminated. In

  10. Spatially and spectrally resolved 10 mu m emission in Herbig Ae/Be stars

    NARCIS (Netherlands)

    van Boekel, R; Waters, LBFM; Dominik, C; Dullemond, CP; Tielens, AGGM; de Koter, A

    2004-01-01

    We present new mid-infrared spectroscopy of the emission from warm circumstellar dust grains in the Herbig Ae stars HD 100546. HD 97048 and HD 104237, with a spatial resolution Of of approximate to0."9. We find that the emission in the UIR bands at 8.6, 11.3 and (HD 97048 only) 12.7 mum is extended

  11. Surface abundances of OC supergiants

    CERN Document Server

    Martins, F; Bouret, J -C; Barba, R; Howarth, I

    2016-01-01

    Some O and B stars show unusually strong or weak lines of carbon and/or nitrogen. These objects are classified as OBN or OBC stars. It has recently been shown that nitrogen enrichment and carbon depletion are the most likely explanations for the existence of the ON class. We investigate OC stars (all being supergiants) to check that surface abundances are responsible for the observed anomalous line strengths. We perform a spectroscopic analysis of three OC supergiants using atmosphere models. A fourth star was previously studied by us. Our sample thus comprises all OC stars known to date in the Galaxy. We determine the stellar parameters and He, C, N, and O surface abundances. We show that all stars have effective temperatures and surface gravities fully consistent with morphologically normal O supergiants. However, OC stars show little, if any, nitrogen enrichment and carbon surface abundances consistent with the initial composition. OC supergiants are thus barely chemically evolved, unlike morphologically n...

  12. THE ROTATION PERIOD OF HD-77581 (VELA X-1)

    NARCIS (Netherlands)

    ZUIDERWIJK, EJ

    1995-01-01

    The rotation period of HD 77581, supergiant primary in the X-ray binary Vela X-1, is determined from an analysis of selected absorption line profiles. The rotation rate determined from He I line profiles is 0.67 +/- 0.04 times that of the binary angular velocity, corresponding to a rotation velocity

  13. Diamonds in HD 97048

    CERN Document Server

    Habart, E; Natta, A; Carbillet, M

    2004-01-01

    We present adaptive optics high angular resolution ($\\sim0\\farcs$1) spectroscopic observations in the 3 $\\mu$m region of the Herbig Ae/Be star HD 97048. For the first time, we spatially resolve the emission in the diamond features at 3.43 and 3.53 $\\mu$m and in the adjacent continuum. Using both the intensity profiles along the slit and reconstructed two-dimensional images of the object, we derive full-width at half-maximum sizes consistent with the predictions for a circumstellar disk seen pole-on. The diamond emission originates in the inner region ($R \\lesssim 15$ AU) of the disk.

  14. The Temperatures of Red Supergiants

    NARCIS (Netherlands)

    Davies, Ben; Kudritzki, Rolf-Peter; Plez, Bertrand; Trager, Scott; Lançon, Ariane; Gazak, Zach; Bergemann, Maria; Evans, Chris; Chiavassa, Andrea

    2013-01-01

    We present a re-appraisal of the temperatures of red supergiants (RSGs) using their optical and near-infrared spectral energy distributions (SEDs). We have obtained data of a sample of RSGs in the Magellanic Clouds using VLT+XSHOOTER, and we fit MARCS model atmospheres to different regions of the sp

  15. The Temperatures of Red Supergiants

    NARCIS (Netherlands)

    Davies, Ben; Kudritzki, Rolf-Peter; Plez, Bertrand; Trager, Scott; Lancon, Ariane; Gazak, Zach; Bergemann, Maria; Evans, Chris; Chiavassa, Andrea

    2013-01-01

    We present a re-appraisal of the temperatures of Red Supergiants (RSGs) using their optical and near-infrared spectral energy distributions (SEDs). We have obtained data of a sample of RSGs in the Magellanic Clouds using VLT+XSHOOTER, and we fit MARCS model atmospheres to different regions of the sp

  16. HD5980

    OpenAIRE

    Koenigsberger, C

    2015-01-01

    HD5980 is a multiple system containing at least 3 very massive and luminous stars. Located in the Small Magellanic Cloud, it is an ideal system for studying the massive star structure and evolutionary processes in low-metallicity environments. Intensely observed over the past few decades, HD5980 is a treasure trove of information on stellar wind structure, on wind-wind collisions and on the formation of wind-blown circumstellar structures. In addition, its characteristics suggest that the ecl...

  17. Red supergiants and stellar evolution

    CERN Document Server

    Ekström, Sylvia; Meynet, Georges; Groh, Jose; Granada, Anahí

    2013-01-01

    We review the significant role played by red supergiants (RSGs) in stellar populations, and some challenges and questions they raise for theoretical stellar evolution. We present how metallicity and rotation modify the way stars go to the red part of the Hertzsprung- Russell diagram or come back from it, and how RSGs might keep a trace of their main-sequence evolution. We compare theoretical popu- lation ratios with observed ones.

  18. Magnetic fields in PMS stars: HARPS spectropolarimetry of sharp-lined Herbig Ae stars

    OpenAIRE

    Järvinen, Silva P.; Carroll, Thorsten A.; Hubrig, Swetlana; Schöller, Markus; Ilyin, Ilya; Korhonen, Heidi H.; Feiden, Gregory A.

    2016-01-01

    Herbig Ae/Be-type stars are analogs of T Tauri stars in the higher mass  range. Spectropolarimetric studies involving sharp-lined Herbig Ae stars  appear to be a promising approach for the detection of their magnetic fields.  We report the results of our HARPS high-resolution spectropolarimetric  analysis of four Herbig Ae stars with low v sin i values: HD 101412,  HD 104237, HD 190073, and PDS 2. The role of contamination by the surrounding  wa...

  19. HD5980

    Science.gov (United States)

    Koenigsberger, C.

    HD5980 is a multiple system containing at least 3 very massive and luminous stars. Located in the Small Magellanic Cloud, it is an ideal system for studying the massive star structure and evolutionary processes in low-metallicity environments. Intensely observed over the past few decades, HD5980 is a treasure trove of information on stellar wind structure, on wind-wind collisions and on the formation of wind-blown circumstellar structures. In addition, its characteristics suggest that the eclipsing WR+LBV stars of the system are the product of quasihomogeneous chemical evolution, thus making them candidate pair production supernovae or GRB progenitors. This paper summarizes some of the outstanding results derived from half a century of observations and recent theoretical studies.

  20. Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light

    CERN Document Server

    Garufi, Antonio; Schmid, Hans Martin; Avenhaus, Henning; Buenzli, Esther; Wolf, Sebastian

    2014-01-01

    The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric fac...

  1. Yellow supergiants in open clusters

    International Nuclear Information System (INIS)

    Superluminous giant stars (SLGs) have been reported in young globular clusters in the Large Magellanic Cloud (LMC). These stars appear to be in the post-asymptotic-giant-branch phase of evolution. This program was an investigation of galactic SLG candidates in open clusters, which are more like the LMC young globular clusters. These were chosen because luminosity, mass, and age determinations can be made for members since cluster distances and interstellar reddenings are known. Color magnitude diagrams were searched for candidates, using the same selection criteria as for SLGs in the LMC. Classification spectra were obtained of 115 program stars from McGraw-Hill Observatory and of 68 stars from Cerro Tololo Inter-American Observatory Chile. These stars were visually classified on the MK system using spectral scans of standard stars taken at the respective observations. Published information was combined with this program's data for 83 stars in 30 clusters. Membership probabilities were assigned to these stars, and the clusters were analyzed according to age. It was seen that the intrinsically brightest supergiants are found in the youngest clusters. With increasing cluster age, the absolute luminosities attained by the supergiants decline. Also, it appears that the evolutionary tracks of luminosity class II stars are more similar to those of class I than of class III

  2. The complex circumstellar environment of HD142527

    CERN Document Server

    Verhoeff, A P; Pantin, E; Waters, L B F M; Tielens, A G G M; Honda, M; Fujiwara, H; Bouwman, J; van Boekel, R; Dougherty, S M; de Koter, A; Dominik, C; Mulders, G D

    2011-01-01

    The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of infrared to stellar luminosity. Its properties differ considerably from other Herbig Ae/Be stars. This suggests that the disk surrounding HD142527 is in an uncommon evolutionary stage. We aim for a better understanding of the geometry and evolutionary status of the circumstellar material around the Herbig Ae/Be star HD142527. We map the composition and spatial distribution of the dust around HD142527. We analyze SEST and ATCA millimeter data, VISIR N and Q-band imaging and spectroscopy. We gather additional relevant data from the literature. We use the radiative transfer code MCMax to construct a model of the geometry and density structure of the circumstellar matter, which fits all of the observables satisfactorily. We find...

  3. Large dust gaps in the transitional disks of HD 100453 and HD 34282

    CERN Document Server

    Khalafinejad, S; Marinas, N; Tielens, A G G M

    2015-01-01

    The formation of dust gaps in protoplanetary disks is one of the most important signposts of disk evolution and possibly the formation of planets. We aim to characterize the 'flaring' disk structure around the Herbig Ae/Be stars HD 100453 and HD 34282. Their spectral energy distributions (SEDs) show an emission excess between 15-40{\\mu}m, but very weak (HD 100453) and no (HD 34282) signs of the 10 and 20 {\\mu}m amorphous silicate features. We investigate whether this implies the presence of large dust gaps. In this work, spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE are investigated. We perform radiative transfer modeling and examine the radial distribution of dust. We simultaneously fit the Q-band images and SEDs of HD 100453 and HD 34282. Our solutions require that the inner-halos and outer-disks are likely separated by large dust gaps that are depleted wih respect to the outer disk by a factor of 1000 or more. The inner edges of the outer disks of HD 100453 and HD 34282 hav...

  4. THE TEMPERATURES OF RED SUPERGIANTS

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Ben [Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom); Kudritzki, Rolf-Peter; Gazak, Zach [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Plez, Bertrand [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS, F-34095 Montpellier (France); Trager, Scott [Kapteyn Institute, University of Groningen, P.O. Box 800, 9700-AV Groningen (Netherlands); Lancon, Ariane [Observatoire Astronomique and CNRS UMR 7550, Universite de Strasbourg, F-67000 Strasbourg (France); Bergemann, Maria [Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Evans, Chris [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Chiavassa, Andrea [CNRS Laboratoire Lagrange, Universite de Nice Sophia-Antipolis, Observatoire de la Cote d' Azur, BP 4229, F-06304 Nice Cedex 4 (France)

    2013-04-10

    We present a re-appraisal of the temperatures of red supergiants (RSGs) using their optical and near-infrared spectral energy distributions (SEDs). We have obtained data of a sample of RSGs in the Magellanic Clouds using VLT+XSHOOTER, and we fit MARCS model atmospheres to different regions of the spectra, deriving effective temperatures for each star from (1) the TiO bands, (2) line-free continuum regions of the SEDs, and (3) the integrated fluxes. We show that the temperatures derived from fits to the TiO bands are systematically lower than the other two methods by several hundred kelvin. The TiO fits also dramatically overpredict the flux in the near-IR, and imply extinctions which are anomalously low compared to neighboring stars. In contrast, the SED temperatures provide good fits to the fluxes at all wavelengths other than the TiO bands, are in agreement with the temperatures from the flux integration method, and imply extinctions consistent with nearby stars. After considering a number of ways to reconcile this discrepancy, we conclude that three-dimensional effects (i.e., granulation) are the most likely cause, as they affect the temperature structure in the upper layers where the TiO lines form. The continuum, however, which forms at much deeper layers, is apparently more robust to such effects. We therefore conclude that RSG temperatures are much warmer than previously thought. We discuss the implications of this result for stellar evolution and supernova progenitors, and provide relations to determine the bolometric luminosities of RSGs from single-band photometry.

  5. Investigating the transitional nature of extreme O-type supergiants in X-rays

    Science.gov (United States)

    De Becker, Michael

    2011-10-01

    We propose to investigate the X-ray properties of HD14947, an O5 supergiant believed to be a transition object between O and Wolf-Rayet stars. Stars belonging to this scarce category display several properties strongly pointing to their transitional status, including broad and strong emission lines in the visible and infrared, and the existence is some cases of surrounding nebulae similar to those existing close to WR stars. We request observation time with XMM-Newton to check whether the X-ray emission of HD14947 deviates significantly from the expected behaviour of regular O-type stars, as recently revealed by our team on the basis of an XMM-Newton observation of a similar object, attempting to establish an additional transition criterion in X-rays for evolved O-type stars.

  6. Hardware Implementation of AES

    Directory of Open Access Journals (Sweden)

    Aakrati Chaturvedi

    2014-01-01

    Full Text Available The Advanced Encryption Standard algorithm can be efficiently programmed in software and implemented in hardware. Field Programmable Gate Array (FPGA devices are considered as efficient and cost effective solution for hardware. This research is in context to efficient hardware implementation of AES algorithm with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. This research is in context to efficient hardware implementation of AES algorithm with 128-192-256 key all in one module with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. The software part has been created, processed and simulated through Xilinx ISE 9.2. A compact design approach has been chosen to implement the algorithm with minimal hardware. As for hardware, Spartan 3AN family device (XC3S700A device is used

  7. Gas in the protoplanetary disc of HD 169142 : Herschel's view

    NARCIS (Netherlands)

    Meeus, G.; Pinte, C.; Woitke, P.; Montesinos, B.; Mendigutia, I.; Riviere-Marichalar, P.; Eiroa, C.; Mathews, G. S.; Vandenbussche, B.; Howard, C. D.; Roberge, A.; Sandell, G.; Duchene, G.; Menard, F.; Grady, C. A.; Dent, W. R. F.; Kamp, I.; Augereau, J. C.; Thi, W. F.; Tilling, I.; Alacid, J. M.; Andrews, S.; Ardila, D. R.; Aresu, G.; Barrado, D.; Brittain, S.; Ciardi, D. R.; Danchi, W.; Fedele, D.; de Gregorio-Monsalvo, I.; Heras, A.; Huelamo, N.; Krivov, A.; Lebreton, J.; Liseau, R.; Martin-Zaidi, C.; Mora, A.; Morales-Calderon, M.; Nomura, H.; Pantin, E.; Pascucci, I.; Phillips, N.; Podio, L.; Poelman, D. R.; Ramsay, S.; Riaz, B.; Rice, K.; Solano, E.; White, G. J.; Williams, J. P.; Wright, G.; Walker, H.

    2010-01-01

    In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the open time key program GASPS, which is aimed a

  8. HARPS spectropolarimetry of Herbig Ae/Be stars

    CERN Document Server

    Hubrig, S; Schoeller, M; Curto, G Lo

    2013-01-01

    Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right- and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD58647 and HD98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD104237 by Donati et al. and confirm the previous detection of a...

  9. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights

    CERN Document Server

    Järvinen, S P; Hubrig, S; Schöller, M; Ilyin, I; Korhonen, H; Pogodin, M; Drake, N A

    2015-01-01

    Several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be promising for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. High-resolution spectropolarimetric observations of the three sharp-lined Herbig Ae stars HD101412, HD104237, and HD190073 have been obtained in recent years with the HARPS. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition method. We discovered that different line...

  10. Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD 116657, HD 138213, HD 155375, HD 159560, HD 196544 and HD 204188

    OpenAIRE

    Stateva, I.; Iliev, I. Kh; Budaj, J.

    2012-01-01

    We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abun...

  11. The Red Supergiant Content of M31

    CERN Document Server

    Massey, Philip

    2016-01-01

    We investigate the red supergiant (RSG) population of M31, obtaining radial velocities of 255 stars. These data substantiate membership of our photometrically-selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar-metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 Mo stars, while the vast majority evolved from stars with initial masses of 20 Mo or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is o...

  12. Supergiant Fast X-ray Transients

    CERN Document Server

    Sidoli, Lara

    2011-01-01

    The phenomenology of a subclass of High Mass X-ray Binaries hosting a blue supergiant companion, the so-called Supergiant Fast X-ray Transients (SFXTs), is reviewed. Their number is growing, mainly thanks to the discoveries performed by the INTEGRAL satellite, then followed by soft X-rays observations (both aimed at refining the source position and at monitoring the source behavior) leading to the optical identification of the blue supergiant nature of the donor star. Their defining properties are a transient X-ray activity consisting of sporadic, fast and bright flares, (each with a variable duration between a few minutes and a few hours), reaching 1E36-1E37 erg/s. The quiescence is at a luminosity of 1E32 erg/s, while their more frequent state consists of an intermediate X-ray emission of 1E33-1E34 erg/s (1-10 keV). Only the brightest flares are detected by INTEGRAL (>17 keV) during short pointings, with no detected persistent emission. The physical mechanism driving the short outbursts is still debated, al...

  13. The Disk and Wind of HD 104237

    Science.gov (United States)

    Danks, Anthony

    2000-07-01

    STIS GTO studies of intermediate-mass stars have revealed circumstellar disks and associated nebulosities in 44% of our sample. The largest-scale nebulosity is seen in those systems with emission in the unidentified infrared bands, which have been interpreted as being associated with C-H stretch and bend modes in small organic grains {sometimes interpreted as polycyclic aromatic hydrocarbons}. We wish to test this hypothesis with coronagraphic observations of the nearby Herbig Ae star, HD 104237 {d=115pc} which shows UIB features in its ISO SWS spectrum. This system is also known to have lyman alpha in emission, and is thus a prime candidate for mapping the spatial extent of the wind and to search for the presence of a collimated outflow similar to that seen in HD 163296. We will follow up on the coronagraphic imaging with a G140M long slit spectrum at Lyman alpha, and a G140L spectrum.

  14. Aes grave iz Jesenica

    OpenAIRE

    Bonačić Mandinić, Maja

    2009-01-01

    U zbirci Arheološkog muzeja u Splitu čuva se primjerak aes grave tipa Apolon/Apolon (RRC 18/1). Pripada emisiji kovnice u Rimu iz 275. do 270. godine prije Krista. Nađen je oko 1901. godine u Jesenicama. Bilo kakve pojedinosti o kontekstu nalaza nisu poznate. Jesenice su selo na oko 200 do 250 m nadmorske visine, na padini Peruna - južna kosa planine Mosor. Uz ostale helenističke nalaze sa šireg područja Jesenica, na potezu uz obalu između Splita i Omiša, ovaj nalaz bi mogao svjedočiti o vezi...

  15. Pro Tools HD

    CERN Document Server

    Camou, Edouard

    2013-01-01

    An easy-to-follow guide for using Pro Tools HD 11 effectively.This book is ideal for anyone who already uses ProTools and wants to learn more, or is new to Pro Tools HD and wants to use it effectively in their own audio workstations.

  16. The Red Supergiant Content of M31*

    Science.gov (United States)

    Massey, Philip; Evans, Kate Anne

    2016-08-01

    We investigate the red supergiant (RSG) population of M31, obtaining the radial velocities of 255 stars. These data substantiate membership of our photometrically selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B ‑ V, V ‑ R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25–30 M ⊙ stars, while the vast majority evolved from stars with initial masses of 20 M ⊙ or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; i.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. This paper uses data products produced by the OIR Telescope Data Center, supported by the Smithsonian Astrophysical Observatory.

  17. Lights, camera, A&E.

    Science.gov (United States)

    Gould, Mark

    Channel 4 series 24 Hours in A&E was one of the television highlights of 2011. Filmed at King's College Hospital in London, it showed the reality of life in an A&E department and may have improved the public's understanding of nursing. PMID:22324233

  18. References: AePW publications

    Data.gov (United States)

    National Aeronautics and Space Administration — This page is the repository for the publications resulting from the AePW. This includes the special sessions at conferences: AIAA ASM 2012, Grapevine TX; AIAA SDM...

  19. Supernova Shock Breakout from a Red Supergiant

    CERN Document Server

    Schawinski, Kevin; Wolf, Christian; Podsiadlowski, Philipp; Sullivan, Mark; Steenbrugge, Katrien C; Bell, Tony; Roeser, Hermann-Josef; Walker, Emma; Astier, Pierre; Balam, Dave; Balland, Christophe; Basa, Stephane; Carlberg, Ray; Conley, Alex; Fouchez, Dominque; Guy, Julien; Hardin, Delphine; Hook, Isobel; Howell, Andy; Pain, Reynald; Perrett, Kathy; Pritchet, Chris; Regnault, Nicolas; Yi, Sukyoung K

    2008-01-01

    Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic `core-collapse' supernova. Such events are usually detected long after the star has exploded. Here we report the first detection of the radiative precursor from a supernova shock before it has reached the surface of a star followed by the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve show that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a promising and novel way to probe the physics of core-collapse supernovae and the internal structures of their progenitors.

  20. Supergiant halos as an integral record of natural pionic radioactivity

    OpenAIRE

    Ion, D. B.; Ion-Mihai, Reveica; Ion, M. L.; Sandru, Adriana I.

    2004-01-01

    In this paper an unified interpretation of the supergiant halos (SGH), discovered by Grady, Walker and Laemmlein, is discussed. So, it is proved that SGH`s can be considered as integral records of the nuclear pionic radioactivity.

  1. (abstract) Airborne Emission Spectrometer (AES)

    Science.gov (United States)

    Beer, Reinhard

    1994-01-01

    AES is a low-cost analog of the TES downlooking modes. Because AES operates at ambient temperature, limb-viewing is not possible. The first flight of AES took place in April 1994 on the NASA P3B aircraft out of Wallops Island, VA. While planned as an engineering test flight, spectra were successfully acquired both over the Atlantic Ocean and the area of the Great Dismal Swamp on the Virginia-North Carolina border. At this writing (July 1994), a second series of flights on the NASA DC8 aircraft out of Ames RC,CA is in progress. By the time of the workshop, a third series using the NASA C130 should have been accomplished.

  2. On the binarity of Herbig Ae/Be stars

    CERN Document Server

    Baines, D; Porter, J; Pozzo, M; Baines, Deborah; Oudmaijer, Rene; Porter, John; Pozzo, Monica

    2005-01-01

    We present high resolution spectro-astrometry of a sample of 28 Herbig Ae/Be and 3 F-type pre-main sequence stars. The spectro-astrometry is shown from both empirical and simulated data to be capable of detecting binary companions that are fainter by up to 6 magnitudes at separations larger than 0.1 arcsec. The nine targets that were previously known to be a binary are all detected. In addition, we report the discovery of 6 new binaries and present 5 further possible binaries. The resulting binary fraction of 68+/-11 per cent is the largest reported for any observed sample of Herbig Ae/Be stars, presumably because of the exquisite sensitivity of spectro-astrometry for detecting binary systems. The data hint that the binary frequency of the Herbig Be stars is larger than for the Herbig Ae stars. The appendix presents model simulations to assess the capabilities of spectro-astrometry and reinforces the empirical findings. Two objects, HD 87643 and Z CMa, display evidence for asymmetric outflows. Finally, the po...

  3. Is macroturbulent broadening in OB Supergiants related to pulsations?

    CERN Document Server

    Simón-Díaz, S; Herrero, A; Castro, N; Puls, J; Aerts, C

    2010-01-01

    The spectrum of O and B Supergiants is known to be affected by an important extra line-broadening (usually called \\macro) that adds to stellar rotation. Recent analysis of high resolution spectra has shown that the interpretation of this line-broadening as a consequence of large-scale turbulent motions would imply highly super-sonic velocity fields, making this scenario quite improbable. Stellar oscillations have been proposed as a likely alternative explanation. We present first encouraging results of an observational project aimed at investigating the $macroturbulent$ broadening in O and B Supergiants, and its possible connection with spectroscopic variability phenomena and stellar oscillations: a) all the studied B Supergiants show line profile variations, quantified by means of the first () and third velocity () moments of the lines, b) there is a strong correlation between the peak-to-peak amplitudes of the and variability and the size of the extra-broadening.

  4. Spectral type, temperature, and evolutionary stage in cool supergiants

    Science.gov (United States)

    Dorda, Ricardo; Negueruela, Ignacio; González-Fernández, Carlos; Tabernero, Hugo M.

    2016-07-01

    Context. In recent years, our understanding of red supergiants has been questioned by strong disagreements between stellar atmospheric parameters derived with different techniques. Temperature scales have been disputed, and the possibility that spectral types do not depend primarily on temperature has been raised. Aims: We explore the relations between different observed parameters, and we explore the ability to derive accurate intrinsic stellar parameters from these relations through the analysis of the largest spectroscopic sample of red supergiants to date. Methods: We obtained intermediate-resolution spectra of a sample of about 500 red supergiants in the Large and the Small Magellanic Cloud. From these spectra, we derive spectral types and measure a large set of photospheric atomic lines. We explore possible correlations between different observational parameters, also making use of near- and mid-infrared colours and literature on photometric variability. Results: Direct comparison between the behaviour of atomic lines (Fe i, Ti i, and Ca ii) in the observed spectra and a comprehensive set of synthetic atmospheric models provides compelling evidence that effective temperature is the prime underlying variable driving the spectral-type sequence between early G and M2 for supergiants. In spite of this, there is a clear correlation between spectral type and luminosity, with later spectral types tending to correspond to more luminous stars with heavier mass loss. This trend is much more marked in the LMC than in the SMC. The population of red supergiants in the SMC is characterised by a higher degree of spectral variability, early spectral types (centred on type K1) and low mass-loss rates (as measured by dust-sensitive mid-infrared colours). The population in the LMC displays less spectroscopic variability and later spectral types. The distribution of spectral types is not single-peaked. Instead, the brightest supergiants have a significantly different

  5. Toepassing ICP-AES op het RIKILT

    NARCIS (Netherlands)

    Ruig, de W.G.

    1980-01-01

    Rapportage over de toepassing van ICP-AES op het RIKILT. Bij ICP-AES worden twee manieren van lichtemissie detectie toegepast nl. simultaan en sequentieel. De voor- en nadelen van ICP-AES t.o.v. AAS worden op een rij gezet.

  6. Discovery of SiO Band Emission from Galactic B[e] Supergiants

    Science.gov (United States)

    Kraus, M.; Oksala, M. E.; Cidale, L. S.; Arias, M. L.; Torres, A. F.; Borges Fernandes, M.

    2015-02-01

    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulate in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, HD 327083, and CPD-57 2874. From model fits, we find that in all these stars the SiO bands are rotationally broadened with a velocity lower than observed in the CO band forming regions, suggesting that SiO forms at larger distances from the star. Hence, searching for and analyzing these bands is crucial for studying the structure and kinematics of circumstellar disks, because they trace complementary regions to the CO band formation zone. Moreover, since SiO molecules are the building blocks for silicate dust, their study might provide insight in the early stage of dust formation. Based on observations collected with the ESO VLT Paranal Observatory under program 093.D-0248(A).

  7. DISCOVERY OF SiO BAND EMISSION FROM GALACTIC B[e] SUPERGIANTS

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, M. [Astronomický ústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov (Czech Republic); Oksala, M. E. [LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris Diderot, 5 place Jules Janssen, F-92190, Meudon (France); Cidale, L. S.; Arias, M. L.; Torres, A. F. [Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata (Argentina); Fernandes, M. Borges, E-mail: michaela.kraus@asu.cas.cz [Observatório Nacional, Rua General José Cristino 77, 20921-400 São Cristovão, Rio de Janeiro (Brazil)

    2015-02-20

    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulate in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, HD 327083, and CPD-57 2874. From model fits, we find that in all these stars the SiO bands are rotationally broadened with a velocity lower than observed in the CO band forming regions, suggesting that SiO forms at larger distances from the star. Hence, searching for and analyzing these bands is crucial for studying the structure and kinematics of circumstellar disks, because they trace complementary regions to the CO band formation zone. Moreover, since SiO molecules are the building blocks for silicate dust, their study might provide insight in the early stage of dust formation.

  8. Supergiant Fast X-ray Transients: a Review

    CERN Document Server

    Romano, P; Gang, the SFXT

    2010-01-01

    We review the status of our knowledge on supergiant fast X-ray transients (SFXTs), a new hot topic in multi wavelength studies of binaries. We discuss the mechanisms believed to power these transients and then highlight the unique contribution Swift is giving to this field, and how new technology complements and sometimes changes the view of things.

  9. Magnetic braking of stellar cores in red giants and supergiants

    Energy Technology Data Exchange (ETDEWEB)

    Maeder, André; Meynet, Georges, E-mail: andre.maeder@unige, E-mail: georges.meynet@unige.ch [Geneva Observatory, Geneva University, CH-1290 Sauverny (Switzerland)

    2014-10-01

    Magnetic configurations, stable on the long term, appear to exist in various evolutionary phases, from main-sequence stars to white dwarfs and neutron stars. The large-scale ordered nature of these fields, often approximately dipolar, and their scaling according to the flux conservation scenario favor a fossil field model. We make some first estimates of the magnetic coupling between the stellar cores and the outer layers in red giants and supergiants. Analytical expressions of the truncation radius of the field coupling are established for a convective envelope and for a rotating radiative zone with horizontal turbulence. The timescales of the internal exchanges of angular momentum are considered. Numerical estimates are made on the basis of recent model grids. The direct magnetic coupling of the core to the extended convective envelope of red giants and supergiants appears unlikely. However, we find that the intermediate radiative zone is fully coupled to the core during the He-burning and later phases. This coupling is able to produce a strong spin down of the core of red giants and supergiants, also leading to relatively slowly rotating stellar remnants such as white dwarfs and pulsars. Some angular momentum is also transferred to the outer convective envelope of red giants and supergiants during the He-burning phase and later.

  10. Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188

    CERN Document Server

    Stateva, I; Budaj, J

    2011-01-01

    We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abundances of several elements were determined. We conclude that all six stars are Am stars. These stars were put into the context of other Am binaries with 10 < Porb < 200 days and their abundance anomalies discussed in the context of possible tidal effects. There is clear anti-correlation of the Am peculiarities with v sin i. However, there seems to be also a correlation with the eccentricity and may be with the orbital period. The dependence on the temperature, age, mass, and microturbulence was studied as well. The ...

  11. The weak magnetic field of the O9.7 supergiant zeta Orionis A

    CERN Document Server

    Bouret, J -C; Martins, F; Escolano, C; Marcolino, W; Lanz, T; Howarth, Ian

    2008-01-01

    We report here the detection of a weak magnetic field of 50 - 100 G on the O9.7 supergiant zeta Ori A, using spectropolarimetric observations obtained with NARVAL at the 2m Telescope Bernard Lyot atop Pic du Midi (France). zeta Ori A is the third O star known to host a magnetic field (along with theta^1 Ori C and HD 191612), and the first detection on a 'normal' rapidly-rotating O star. The magnetic field of zeta Ori A is the weakest magnetic field ever detected on a massive star. The measured field is lower than the thermal equipartition limit (about 100 G). By fitting NLTE model atmospheres to our spectra, we determined that zeta Ori A is a 40 Msun star with a radius of 25 Rsun and an age of about 5 - 6 Myr, showing no surface nitrogen enhancement and losing mass at a rate of about 2x10^(-6) Msol/yr. The magnetic topology of zeta Ori A is apparently more complex than a dipole and involves two main magnetic polarities located on both sides of the same hemisphere; our data also suggest that zeta Ori A rotates...

  12. Discovery of SiO band emission from Galactic B[e] supergiants

    CERN Document Server

    Kraus, Michaela; Cidale, Lydia; Arias, Maria Laura; Torres, Andrea; Fernandes, Marcelo Borges

    2015-01-01

    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulates in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, ...

  13. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights ⋆

    Science.gov (United States)

    Järvinen, S. P.; Carroll, T. A.; Hubrig, S.; Schöller, M.; Ilyin, I.; Korhonen, H.; Pogodin, M.; Drake, N. A.

    2015-12-01

    Aims: Recently, several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. Methods: High-resolution spectropolarimetric observations of the three sharp-lined (vsini< 15 km s-1) Herbig Ae stars HD 101412, HD 104237, and HD 190073 have been obtained in recent years with the HARPS spectrograph in polarimetric mode. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition (SVD) method for Stokes profile reconstruction. Results: We carried out a high-resolution spectropolarimetric analysis of the Herbig Ae star HD 101412 for the first time. We discovered that different line lists yield differences in both the shape of the Stokes V signatures and their field strengths. They could be interpreted in the context of the impact of the circumstellar matter and elemental abundance inhomogeneities on the measurements of the magnetic field. On the other hand, due to the small size of the Zeeman features on the first three epochs and the lack of near-IR observations, circumstellar and photospheric contributions cannot be estimated unambiguously. In the SVD Stokes V spectrum of the SB2 system HD 104237, we detect that the secondary component, which is a T Tauri star, possesses a rather strong magnetic field ⟨Bz⟩ = 129 ± 12 G, while no significant field is present in the primary

  14. Developing A/E Capabilities

    International Nuclear Information System (INIS)

    During the last few years, the methods used by EMPRESARIOS AGRUPADOS and INITEC to perform Architect-Engineering work in Spain for nuclear projects has undergone a process of significant change in project management and engineering approaches. Specific practical examples of management techniques and design practices which represent a good record of results will be discussed. They are identified as areas of special interest in developing A/E capabilities for nuclear projects . Command of these areas should produce major payoffs in local participation and contribute to achieving real nuclear engineering capabities in the country. (author)

  15. Late-Type Red Supergiants: Too Cool for the Clouds?

    Science.gov (United States)

    Levesque, Emily M.; Massey, P.; Olsen, K. A.; Plez, B.

    2006-12-01

    It has long been known that the median spectral types of red supergiants change from M2 I in the Milky Way to M1 I in the Large Magellanic Cloud (LMC) and to K5-7 I in the Small Magellanic Cloud (SMC) (Elias et al 1985, Massey & Olsen 2002). This is now understood in terms of the shifting of the evolutionary tracks to warmer temperatures with decreasing metallicity. Stars falling below the temperatures of these tracks would no longer be in hydrostatic equilibrium. This region of the H-R diagram is known as the Hayashi "forbidden zone". Early work identified supergiants no later than M2 I in the SMC, while in the Milky Way supergiants of spectral class M4 I and later abound. However, our work has identified seven red supergiants in the LMC and four red supergiants in the SMC, all of which have spectral types that are considerably later than the average type observed in their parent galaxy. We find that these stars have radial velocities which are consistent with membership in the Clouds. By fitting our moderate-resolution spectrophotometry of these stars with MARCS stellar atmosphere models of the appropriate metallicities, we also determine their physical parameters and place them on the H-R diagram for comparison with the predictions of current stellar evolutionary tracks. We find that these stars are colder and more luminous than allowed by the predictions of stellar evolutionary theory at these low metallicities. Unsurprisingly, these stars also exhibit unusual variability in V. We then suggest that these stars have such unusual properties because they are in an unstable (and short-lived) phase of their evolutionary lives. This work was supported by the National Science Foundation through AST-0604569 to PM.

  16. Signs of Planetary Formation in the Disk of HD169142

    Science.gov (United States)

    Osorio, M.; Anglada, G.; Carrasco-Gonzalez, C.; Torrelles, J. M.; D'Alessio, P.; Rodriguez, L. F.; Calvet, N.; Gomez, J. F.; Mayén-Gijón, J. M.; Dent, W.

    2013-07-01

    We present 7mm continuum observations at subarcsecond angular resolution, as well as detailed modeling of the disk surrounding the nearby Herbig AeBe star HD 169142. Our modeling of the SED indicates that the system is in an advanced stage of evolution, in which infall and outflow processes have almost halted, and the dust particles have begun to coagulate and settle towards the disk mid-plane to eventually form planetesimals. Our high angular resolution (0."15) VLA observations reveal a region of enhanced 7mm emission with internal substructure, with several local emission peaks at radii 20-40 AU. We interpret these features as signs of planetary formation.

  17. Resolving the evolutionary stage of HD163899 from its oscillation spectrum

    Science.gov (United States)

    Ostrowski, Jakub; Daszynska-Daszkiewicz, Jadwiga; Cugier, Henryk

    2015-08-01

    HD 163899 is the prototype of Slowly Pulsating B-type supergiants (SPBsg), a relatively new class of pulsating variables. Despite the efforts of many groups the physical properties of this object are still poorly known. Due to the lack of good observational data it was impossible to obtain a precise determination of its basic parameters such as effective temperature and gravity. The position of the star on the Hertzsprung-Russel diagram suggested that the star is a supergiant with a mass of about 16 M⊙. It could be in the hydrogen shell-burning phase during the first crossing towards the red giant branch or on the blue loop during core helium burning. The first option seemed to be more plausible due the pulsational properties of the object (Ostrowski & Daszynska-Daszkiewicz 2015).The analysis of the high-resolution spectra from the HARPS spectrograph changed the situation. Our determination of the effective temperature, mass-luminosity ratio and rotational velocity highly prefers the more massive models than previously considered (M=22-25 M⊙). Now it is also possible that the star could be on the main sequence if convective overshooting and rotation are properly included.Using the oscillation spectrum as a gauge, we intend to determine which stage of evolution corresponds better to HD 163899. To this end we use MESA evolutionary code and the non-adiabatic code for stellar pulsations.

  18. HD 100453: A Link Between Gas-Rich Protoplanetary Disks and Gas-Poor Debris Disks

    CERN Document Server

    Collins, K A; Hamaguchi, K; Wisniewski, J P; Brittain, S; Sitko, M; Carpenter, W J; Williams, J P; Mathews, G S; Williger, G M; Van Boekel, R; Carmona, A; Henning, T; Ancker, M E van den; Meeus, G; Chen, X P; Petre, R; Woodgate, B E

    2009-01-01

    HD 100453 has an IR spectral energy distribution (SED) which can be fit with a power-law plus a blackbody. Previous analysis of the SED suggests that the system is a young Herbig Ae star with a gas-rich, flared disk. We reexamine the evolutionary state of the HD 100453 system by refining its age (based on a candidate low-mass companion) and by examining limits on the disk extent, mass accretion rate, and gas content of the disk environment. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with a spectral type of M4.0V - M4.5V, and derive an age of 10 +/- 2 Myr. We find no evidence of mass accretion onto the star. Chandra ACIS-S imagery shows that the Herbig Ae star has L_X/L_Bol and an X-ray spectrum similar to non-accreting Beta Pic Moving Group early F stars. Moreover, the disk lacks the conspicuous Fe II emission and excess FUV continuum seen in spectra of actively accreting Herbig Ae stars, and from the FUV continuum, we find the accretion rate is < 1.4x10^-9 M_Sun yr^-1. A...

  19. HD 285507b

    DEFF Research Database (Denmark)

    Quinn, Samuel N.; White, Russel J.; Latham, David W.;

    2014-01-01

    We report the discovery of the first hot Jupiter in the Hyades open cluster. HD 285507b orbits a V = 10.47 K4.5V dwarf (M * = 0.734 M ☉; R * = 0.656 R ☉) in a slightly eccentric () orbit with a period of days. The induced stellar radial velocity corresponds to a minimum companion mass of M Psin i...... = 0.917 ± 0.033 M Jup. Line bisector spans and stellar activity measures show no correlation with orbital phase, and the radial velocity amplitude is independent of wavelength, supporting the conclusion that the variations are caused by a planetary companion. Follow-up photometry indicates with high...

  20. Biclique cryptanalysis of the full AES

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Khovratovich, Dmitry; Rechberger, Christian

    2011-01-01

    Since Rijndael was chosen as the Advanced Encryption Standard (AES), improving upon 7-round attacks on the 128-bit key variant (out of 10 rounds) or upon 8-round attacks on the 192/256-bit key variants (out of 12/14 rounds) has been one of the most difficult challenges in the cryptanalysis of block...... ciphers for more than a decade. In this paper, we present the novel technique of block cipher cryptanalysis with bicliques, which leads to the following results: The first key recovery method for the full AES-128 with computational complexity 2126.1. The first key recovery method for the full AES-192...... with computational complexity 2189.7. The first key recovery method for the full AES-256 with computational complexity 2254.4. Key recovery methods with lower complexity for the reduced-round versions of AES not considered before, including cryptanalysis of 8-round AES-128 with complexity 2124.9. Preimage search...

  1. Manufacture of Automatic Heating Equipment for AES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper introduced the design and application of automaticheating equipment for Auger Emission Spectroscopy (AES). The special electric furnace used in the AES was designed, the Al2O3 glass window which allows both visible light and infrared ray to pass through was made, and the MA2S/B thermo-meter based on infrared ray radiant energy from the sample was selected. The equipment gives dynamic analyzingby AES. It offers possibilities for widening the fields of materials surface and interface research . As a sample , the FeCr17 alloy was studied by in situ AES in the heating progress with the help of automaticheating equipment.

  2. A New Survey for Red Supergiants in the Magellanic Clouds

    Science.gov (United States)

    González-Fernández, C.; Negueruela, I.; Dorda, R.

    2016-10-01

    We present a pilot program focused on the red supergiant population of the Magellanic Clouds, with the intent of extending the current known sample to include the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behavior to other Galactic and extra-galactic environments. For a pool of candidates selected over near-infrared photometry, we obtain medium resolution multi-object spectroscopy to confirm their nature and their membership in the clouds. Around two hundred new red supergiants have been detected, hinting at a yet-to-be-observed large population. Based on this sample, new a priori classification criteria are investigated, combining mid- and near-infrared photometry to improve the observational efficiency of programs similar to this. A more complete and detailed analysis of this dataset can be found in González- Fernández et al. (2015).

  3. Magnetic braking of stellar cores in red giants and supergiants

    CERN Document Server

    Maeder, Andre

    2014-01-01

    Magnetic configurations, stable on the long term, appear to exist in various evolutionary phases, from Main-Sequence stars to white dwarfs and neutron stars. The large scale ordered nature of these fields, often approximately dipolar, and their scaling according to the flux conservation scenario favor the model of a fossil field (Duez et al. 2010). We make some first estimates of the magnetic coupling between the stellar cores and the outer layers in red giants and supergiants. Analytical expressions of the truncation radius of the field coupling are established for a convective envelope and for a rotating radiative zone with horizontal turbulence. The timescales of the internal exchanges of angular momentum are considered. Numerical estimates are made on the basis of recent model grids. The direct magnetic coupling of the core to the extended convective envelope of red giants and supergiants appears unlikely. However, we find that the intermediate radiative zone is fully coupled to the core during the He-bur...

  4. Surface magnetism of cool giant and supergiant stars

    CERN Document Server

    Korhonen, Heidi

    2013-01-01

    The existence of starspots on late-type giant stars in close binary systems, that exhibit rapid rotation due to tidal locking, has been known for more than five decades. Photometric monitoring spanning decades has allowed studying the long-term magnetic activity in these stars revealing complicated activity cycles. The development of observing and analysis techniques that has occurred during the past two decades has also enabled us to study the detailed starspot and magnetic field configurations on these active giants. In the recent years magnetic fields have also been detected on slowly rotating giants and supergiant stars. In this paper I review what is known of the surface magnetism in the cool giant and supergiant stars.

  5. Chromosome isolation by flow sorting in Aegilops umbellulata and Ae. comosa and their allotetraploid hybrids Ae. biuncialis and Ae. geniculata.

    Directory of Open Access Journals (Sweden)

    István Molnár

    Full Text Available This study evaluates the potential of flow cytometry for chromosome sorting in two wild diploid wheats Aegilops umbellulata and Ae. comosa and their natural allotetraploid hybrids Ae. biuncialis and Ae. geniculata. Flow karyotypes obtained after the analysis of DAPI-stained chromosomes were characterized and content of chromosome peaks was determined. Peaks of chromosome 1U could be discriminated in flow karyotypes of Ae. umbellulata and Ae. biuncialis and the chromosome could be sorted with purities exceeding 95%. The remaining chromosomes formed composite peaks and could be sorted in groups of two to four. Twenty four wheat SSR markers were tested for their position on chromosomes of Ae. umbellulata and Ae. comosa using PCR on DNA amplified from flow-sorted chromosomes and genomic DNA of wheat-Ae. geniculata addition lines, respectively. Six SSR markers were located on particular Aegilops chromosomes using sorted chromosomes, thus confirming the usefulness of this approach for physical mapping. The SSR markers are suitable for marker assisted selection of wheat-Aegilops introgression lines. The results obtained in this work provide new opportunities for dissecting genomes of wild relatives of wheat with the aim to assist in alien gene transfer and discovery of novel genes for wheat improvement.

  6. Long-term spectropolarimetric monitoring of the cool supergiant Betelgeuse

    OpenAIRE

    Bedecarrax, I.; Petit, P.; Aurière, M.; Grunhut, J.; Wade, G.; Chiavassa, A.; Donati, J.-F.; Konstantinova-Antova, R.; Perrin, G.

    2013-01-01

    We report on a long-term monitoring of the cool supergiant Betelgeuse, using the NARVAL and ESPaDOnS high-resolution spectropolarimeters, respectively installed at Telescope Bernard Lyot (Pic du Midi Observatory, France) and at the Canada-France-Hawaii Telescope (Mauna Kea Observatory, Hawaii). The data set, constituted of circularly polarized (Stokes V) and intensity (Stokes I) spectra, was collected between 2010 and 2012. We investigate here the temporal evolution of magnetic field, convect...

  7. Pulsations of blue supergiants before and after helium core ignition

    OpenAIRE

    Ostrowski, Jakub; Daszyńska-Daszkiewicz

    2013-01-01

    We present results of pulsation analyses of B-type supergiant models with masses of $14 - 18 M_\\odot$, considering evolutionary stages before and after helium core ignition. Using a non-adiabatic pulsation code, we compute instability domains for low degree modes. For selected models in these two evolutionary phases, we compare properties of pulsation modes. Significant differences are found in oscillation spectra and the kinetic energy density of pulsation modes.

  8. Mass Losing Asymptotic Giant Branch Stars and Supergiants

    CERN Document Server

    Whitelock, Patricia A; Höfner, Susanne; Wittkowski, Markus; Zijlstra, Albert A

    2016-01-01

    This paper presents a summary of four invited and twelve contributed presentations on asymptotic giant branch stars and red supergiants, given over the course of two afternoon splinter sessions at the 19th Cool Stars Workshop. It highlights both recent observations and recent theory, with some emphasis on high spatial resolution, over a wide range of wavelengths. Topics covered include 3D models, convection, binary interactions, mass loss, dust formation and magnetic fields.

  9. Water vapor on supergiants. The 12 micron TEXES spectra of ? Cephei

    OpenAIRE

    Harper, Graham

    2006-01-01

    PUBLISHED Several recent papers have argued for warm, semidetached, molecular layers surrounding red giant and supergiant stars, a concept known as a MOLsphere. Spectroscopic and interferometric analyses have often corroborated this general picture. Here we present high-resolution spectroscopic data of pure rotational lines of water vapor at 12 ?m for the supergiant ? Cep. This star has often been used to test the concept of molecular layers around supergiants. Given the prediction of an i...

  10. Observations of Supergiant Fast X-ray Transients with LOFT

    CERN Document Server

    Bozzo, E; Ferrigno, C; Esposito, P; Mangano, V

    2012-01-01

    Supergiant Fast X-ray transients are a subclass of high mass X-ray binaries displaying a peculiar and still poorly understood extreme variability in the X-ray domain. These sources undergo short sporadic outbursts (LX ~ 10^36 - 10^37 erg/s), lasting few ks at the most, and spend a large fraction of their time in an intermediate luminosity state at about LX ~ 10^33 - 10^34 erg/s. The sporadic and hardly predictable outbursts of supergiant fast X-ray transients were so far best discovered by large field of view (FOV) coded-mask instruments; their lower luminosity states require, instead, higher sensitivity focusing instruments to be studied in sufficient details. In this contribution, we provide a summary of the current knowledge on Supergiant Fast X-ray Transients and explore the contribution that the new space mission concept LOFT, the Large Observatory For X-ray Timing, will be able to provide in the field of research of these objects.

  11. Nitrogen Enrichment in Atmospheres of A- and F- Type Supergiants

    CERN Document Server

    Lyubimkov, Leonid S; Korotin, Sergey A; Poklad, Dmitry B; Rachkovskaya, Tamara M; Rostopchin, Sergey I

    2010-01-01

    Using new accurate fundamental parameters of 30 Galactic A and F supergiants, namely their effective temperatures Teff and surface gravities log g, we implemented a non-LTE analysis of the nitrogen abundance in their atmospheres. It is shown that the non-LTE corrections to the N abundances increase with Teff. The nitrogen overabundance as a general feature of this type of stars is confirmed. A majority of the stars has a nitrogen excess [N/Fe] between 0.2 and 0.9 dex with the maximum position of the star's distribution on [N/Fe] between 0.4 and 0.7 dex. The N excesses are discussed in light of predictions for B-type main sequence (MS) stars with rotationally induced mixing and for their next evolutionary phase, i.e. A- and F-type supergiants that have experienced the first dredge-up. Rotationally induced mixing in the MS progenitors of the supergiants may be a significant cause of the nitrogen excesses. When comparing our results with predictions of the theory developed for stars with the mixing, we find that...

  12. ALE: AES-based lightweight authenticated encryption

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Mendel, Florian; Regazzoni, Francesco;

    2014-01-01

    In this paper, we propose a new Authenticated Lightweight Encryption algorithm coined ALE. The basic operation of ALE is the AES round transformation and the AES-128 key schedule. ALE is an online single-pass authenticated encryption algorithm that supports optional associated data. Its security...... relies on using nonces. We provide an optimized low-area implementation of ALE in ASIC hardware and demonstrate that its area is about 2.5 kGE which is almost two times smaller than that of the lightweight implementations for AES-OCB and ASC-1 using the same lightweight AES engine. At the same time......, it is at least 2.5 times more performant than the alternatives in their smallest implementations by requiring only about 4 AES rounds to both encrypt and authenticate a 128-bit data block for longer messages. When using the AES-NI instructions, ALE outperforms AES-GCM, AES-CCM and ASC-1 by a considerable margin...

  13. NEWLY DISCOVERED PLANETS ORBITING HD 5319, HD 11506, HD 75784 AND HD 10442 FROM THE N2K CONSORTIUM

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, Matthew J.; Fischer, Debra A.; Brewer, John M. [Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Payne, Matthew J.; Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Isaacson, Howard T. [Department of Astronomy, University of California, Berkeley, Berkeley, California 94720 (United States)

    2015-01-20

    Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 M {sub Jup}) orbiting stars monitored as part of the Next 2000 target stars (N2K) Doppler Survey program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer planet has an orbital period of 1627.5 days, and the newly discovered inner planet orbits in 223.6 days. A planet has also been discovered orbiting HD 75784 with an orbital period of 341.7 days. There is evidence for a longer period signal; however, several more years of observations are needed to put tight constraints on the Keplerian parameters for the outer planet. Lastly, an additional planet has been detected orbiting HD 10442 with a period of 1043 days.

  14. AES in deficit on Georgian trade

    International Nuclear Information System (INIS)

    According to Vedomosti journal Russian state energy company RAO JES Rossii paid for Georgian assets acquisition to American company AES only 23 million USD, what is less than a tenth of sum which AES had originally paid for it. Thus total transaction value including debts reached 80 millions USD. But internal documents of American AES confirm that Americans paid 260 millions USD for Georgian assets and they took besides over 60 millions USD of obligations. Russians bought Georgian AES assets through Finnish filial Nordic Oy. Thus they obtained 75 per cent share in Telasi company which operates distributive network in Tbilisi, two blocks of plant in Tbilisi and half share in AES-Transenergy company which exports electric energy from Georgia to Turkey. RAO JES besides got managerial laws on Hramesi company which owns two water plants. Russian company controls one fifth of production and 35 per cent of electric energy sale in Georgia by these assets

  15. Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium

    CERN Document Server

    Giguere, Matthew J; Payne, Matthew J; Brewer, John M; Johnson, John Asher; Howard, Andrew W; Isaacson, Howard T

    2014-01-01

    Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly-discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 MJup) orbiting stars monitored as part of the N2K program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously-unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly-discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer pla...

  16. GASPS observations of Herbig Ae/Be stars with PACS/Herschel. The atomic and molecular content of their protoplanetary discs

    CERN Document Server

    Meeus, G; Mendigutia, I; Kamp, I; Thi, W F

    2012-01-01

    We observed a sample of 20 representative Herbig Ae/Be stars and five A-type debris discs with PACS onboard of Herschel. The observations were done in spectroscopic mode, and cover far-IR lines of [OI], [CII], CO, CH+, H2O and OH. We have a [OI]63 micron detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. [OI]145 micron is only detected in 25%, CO J=18-17 in 45% (and less for higher J transitions) of the Herbig Ae/Be stars and for [CII] 157 micron, we often found spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. CH+, first seen in HD 100546, is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and stellar or disc parameters, such as stellar luminosity, UV and X-ray fl...

  17. Attacks and countermeasures on AES and ECC

    DEFF Research Database (Denmark)

    Tange, Henrik; Andersen, Birger

    2013-01-01

    AES (Advanced Encryption Standard) is widely used in LTE and Wi-Fi communication systems. AES has recently been exposed to new attacks which have questioned the overall security of AES. The newest attack is a so called biclique attack, which is using the fact that the content of the state array...... is foreseeable while the rounds are performed. ECC (Elliptic Curve Cryptography) is used as a public key crypto system with the key purpose of creating a private shared between two participants in a communication network. Attacks on ECC include the Pohlig-Hellman attack and the Pollard's rho attack. Furthermore...

  18. New related-key rectangle attacks on reduced AES-192 and AES-256

    Institute of Scientific and Technical Information of China (English)

    WEI YongZhuang; HU YuPu

    2009-01-01

    In this paper, we examine the security of reduced AES-192 and AES-256 against related-key rectangle attacks by exploiting the weakness in the AES key schedule. We find the following two new attacks: 9-round reduced AES-192 with 4 related keys, and 10-round reduced AES-256 with 4 related keys. Our results show that related-key rectangle attack with 4 related keys on 9-round reduced AES-192 requires a data complexity of about 2101 chosen plaintexts and a time complexity of about 2174.8 encryptions, and moreover, related-key rectangle attack with 4 related keys on 10-round reduced AES-256 requires a data complexity of about 297.5 chosen plaintexts and a time complexity of about 2254 encryptions. These attacks are the first known attacks on 9-round reduced AES-192 and 10-round reduced AES-256 with only 4 related keys. Furthermore, we give an improvement of the 10-round reduced AES-192 attack presented at FSE2007, which reduces both the data complexity and the time complexity.

  19. HD depletion in starless cores

    CERN Document Server

    Sipilä, O; Harju, J

    2013-01-01

    Aims: We aim to investigate the abundances of light deuterium-bearing species such as HD, H2D+ and D2H+ in a gas-grain chemical model including an extensive description of deuterium and spin state chemistry, in physical conditions appropriate to the very centers of starless cores. Methods: We combine a gas-grain chemical model with radiative transfer calculations to simulate density and temperature structure in starless cores. The chemical model includes deuterated forms of species with up to 4 atoms and the spin states of the light species H2, H2+ and H3+ and their deuterated forms. Results: We find that HD eventually depletes from the gas phase because deuterium is efficiently incorporated to grain-surface HDO, resulting in inefficient HD production on grains. HD depletion has consequences not only on the abundances of e.g. H2D+ and D2H+, whose production depends on the abundance of HD, but also on the spin state abundance ratios of the various light species, when compared with the complete depletion model ...

  20. The stellar wind velocity field of HD 77581

    CERN Document Server

    Manousakis, A

    2015-01-01

    The early acceleration of stellar winds in massive stars is poorly constrained. The scattering of hard X-ray photons emitted by the pulsar in the high-mass X-ray binary Vela X-1 can be used to probe the stellar wind velocity and density profile close to the surface of its supergiant companion HD 77581. We built a high signal-to-noise and high resolution hard X-ray lightcurve of Vela X-1 measured by Swift/BAT over 300 orbital periods of the system and compared it with the predictions of a grid of hydrodynamic simulations. We obtain a very good agreement between observations and simulations for a narrow set of parameters, implying that the wind velocity close to the stellar surface is twice larger than usually assumed with the standard beta law. Locally a velocity gradient of $\\beta\\sim0.5$ is favoured. Even if still incomplete, hydrodynamic simulations are successfully reproducing several observational properties of Vela X-1.

  1. Magnetic field and convection in the cool supergiant Betelgeuse

    OpenAIRE

    Petit, P.; Aurière, M.; Konstantinova-Antova, R.; Morgenthaler, A.; Perrin, G.; Roudier, T.; Donati, J.-F.

    2011-01-01

    We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly-polarized spectra was obtained using the NARVAL spectropolarimeter at T\\'elescope Bernard Lyot (Pic du Midi Observatory), between 2010 March and April. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5...

  2. Supergiant fast X-ray transients: the Swift monitoring program

    OpenAIRE

    Romano, P; Sidoli, L.; Cusumano, G.; La Parola, V.; Kennea, J. A.; Vercellone, S.; Ducci, L.; Krimm, H.A.; Esposito, P.; Mangano, V.; Paizis, A.; Burrows, D. N.; Gehrels, N.

    2010-01-01

    For the first time, Swift is giving us the opportunity to study supergiant fast X-ray transients (SFXTs) throughout all phases of their life: outbursts, intermediate level, and quiescence. We present our intense monitoring of four SFXTs, observed 2-3 times per week since October 2007. We find that, unexpectedly, SFXTs spend most of their time in an intermediate level of accretion ($L_{X}\\sim 10^{33-34} $ erg s$^{-1}$), characterized by rich flaring activity. We present an overview of our inve...

  3. Outflowing disk winds in B[e] Supergiants

    CERN Document Server

    Cur'e, M; Cidale, L; Cur\\'{e}, Michel; Rial, Diego F.; Cidale, Lydia

    2005-01-01

    The effects of rapid rotation and bi--stability upon the density contrast between the equatorial and polar directions of a B[e] supergiant are investigated. Based on a new slow solution for different high rotational radiation--driven winds and the fact that bi--stability allows a change in the line--force parameters ($\\alpha$, $k$, and $\\delta$), the equatorial densities are about $10^2$--$10^3$ times higher than the polar ones. These values are in qualitative agreement with the observations. This calculation also permits to obtain the aperture angle of the disk.

  4. Calculating Auroral Oval Pattern by AE Index

    Institute of Scientific and Technical Information of China (English)

    CHEN Anqin; LI Jiawei; YANG Guanglin; WANG Jingsong

    2008-01-01

    The relationship between the auroral oval pattern, i.e., location, size, shape, and intensity, and the auroral electrojet activity index (AE index) is studied. It is found that the maximal auroral intensity is elliptically distributed, and the lengths of semimajor and semiminor axes are positively correlated to AE.The intensity along the normal of the auroral oval can be satisfyingly described by a Gaussian distribution,and the maximum and the full width at half maximum of the Gaussian distribution are both positively correlated to AE. Based on these statistical results, a series of experimental formulas as a function of AE are developed to calculate the location, size, shape, and intensity of the auroral oval. These formulas are validated by the auroral images released by SWPC/NOAA.

  5. New Encryption Standard AES%一种新的加密标准 AES

    Institute of Scientific and Technical Information of China (English)

    单玉峰; 潘孟贤

    2002-01-01

    AES是一种新的加密标准,它是分组加密算法,分组长度为128位,密钥长度为128bits、192bits、256bits三种,分别称为AES-128、AES-192、AES-256.本文介绍了AES的加密算法的加密过程,函数定义,密钥扩展过程.

  6. Planetary companions orbiting M giants HD 208527 and HD 220074

    CERN Document Server

    Lee, B -C; Park, M -G

    2012-01-01

    Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) is used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 +/- 5.8 and 672.1 +/- 3.7 days. The RV variations are not apparently related to the surface inhomogeneities and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 +/- 0.4 and 1.2 +/- 0.3 M_Sun, we obtain the minimum masses for the exoplanets of 9.9 +/- 1.7 and 11.1 +/- 1.8 M_Jup around HD 208527 and HD 220074 with an orbital semi-major axis of 2.1 +/- 0.2 and 1.6 +/- 0.1 AU and an eccentricity of 0.08 and 0.14, respectively. We also find that the previously known spectral class...

  7. Searching for supergiant fast X-ray transients with Swift

    CERN Document Server

    Romano, P; Esposito, P; Sbarufatti, B; Haberl, F; Ponti, G; D'Avanzo, P; Ducci, L; Segreto, A; Jin, C; Masetti, N; Del Santo, M; Campana, S; Mangano, V

    2016-01-01

    Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) hosting a neutron star and an OB supergiant companion. We examine the available Swift data, as well as other new or archival/serendipitous data, on three sources: IGR J17407-2808, 2XMM J185114.3-000004, and IGR J18175-2419, whose X-ray characteristics qualify them as candidate SFXT, in order to explore their properties and test whether they are consistent with an SFXT nature. As IGR J17407-2808 and 2XMM J185114.3-000004 triggered the Burst Alert Telescope on board Swift, the Swift data allow us to provide their first arcsecond localisations, leading to an unequivocal identification of the source CXOU J174042.0-280724 as the soft X-ray counterpart of IGR J17407-2808, as well as their first broadband spectra, which can be fit with models generally describing accreting neutron stars in HMXBs. While still lacking optical spectroscopy to assess the spectral type of the companion, we propose 2XMM J185114.3-000004 as a very strong SFXT can...

  8. Blue supergiants as descendants of magnetic main sequence stars

    Science.gov (United States)

    Petermann, I.; Langer, N.; Castro, N.; Fossati, L.

    2015-12-01

    About 10% of the massive main sequence stars have recently been found to host a strong, large scale magnetic field. Both, the origin and the evolutionary consequences of these fields are largely unknown. We argue that these fields may be sufficiently strong in the deep interior of the stars to suppress convection near the outer edge of their convective core. We performed parametrised stellar evolution calculations and assumed a reduced size of the convective core for stars in the mass range 16M⊙ to 28M⊙ from the zero age main sequence until core carbon depletion. We find that such models avoid the coolest part of the main sequence band, which is usually filled by evolutionary models that include convective core overshooting. Furthermore, our "magnetic" models populate the blue supergiant region during core helium burning, i.e., the post-main sequence gap left by ordinary single star models, and some of them end their life in a position near that of the progenitor of Supernova 1987A in the Hertzsprung-Russell diagram. Further effects include a strongly reduced luminosity during the red supergiant stage, and downward shift of the limiting initial mass for white dwarf and neutron star formation.

  9. The blue supergiant MN18 and its bipolar circumstellar nebula

    CERN Document Server

    Gvaramadze, V V; Bestenlehner, J M; Bodensteiner, J; Langer, N; Greiner, J; Grebel, E K; Berdnikov, L N; Beletsky, Y

    2015-01-01

    We report the results of spectrophotometric observations of the massive star MN18 revealed via discovery of a bipolar nebula around it with the Spitzer Space Telescope. Using the optical spectrum obtained with the Southern African Large Telescope, we classify this star as B1 Ia. The evolved status of MN18 is supported by the detection of nitrogen overabundance in the nebula, which implies that it is composed of processed material ejected by the star. We analysed the spectrum of MN18 by using the code CMFGEN, obtaining a stellar effective temperature of \\approx 21 kK. The star is highly reddened, E(B-V)\\approx 2 mag. Adopting an absolute visual magnitude of M_V=-6.8\\pm0.5 (typical of B1 supergiants), MN18 has a luminosity of log L/Lsun \\approx 5.42\\pm0.30, a mass-loss rate of \\approx (2.8-4.5)\\times10^{-7} Msun/yr, and resides at a distance of \\approx 5.6^{+1.5} _{-1.2} kpc. We discuss the origin of the nebula around MN18 and compare it with similar nebulae produced by other blue supergiants in the Galaxy (She...

  10. YELLOW AND RED SUPERGIANTS IN THE LARGE MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    Due to their transitionary nature, yellow supergiants (YSGs) provide a critical challenge for evolutionary modeling. Previous studies within M31 and the Small Magellanic Cloud show that the Geneva evolutionary models do a poor job at predicting the lifetimes of these short-lived stars. Here, we extend this study to the Large Magellanic Cloud (LMC) while also investigating the galaxy's red supergiant (RSG) content. This task is complicated by contamination by Galactic foreground stars that color and magnitude criteria alone cannot weed out. Therefore, we use proper-motions and the LMC's large systemic radial velocity (∼278 km s–1) to separate out these foreground dwarfs. After observing nearly 2000 stars, we identified 317 probable YSGs, 6 possible YSGs, and 505 probable RSGs. Foreground contamination of our YSG sample was ∼80%, while that of the RSG sample was only 3%. By placing the YSGs on the Hertzsprung-Russell diagram and comparing them against the evolutionary tracks, we find that new Geneva evolutionary models do an exemplary job at predicting both the locations and the lifetimes of these transitory objects.

  11. B[e] Supergiants' circumstellar environment: disks or rings?

    CERN Document Server

    Maravelias, G; Aret, A; Cidale, L; Arias, M L; Fernandes, M Borges

    2016-01-01

    B[e] Supergiants are a phase in the evolution of some massive stars for which we have observational evidence but no predictions by any stellar evolution model. The mass-loss during this phase creates a complex circumstellar environment with atomic, molecular, and dust regions usually found in rings or disk-like structures. However, the detailed structure and the formation of the circumstellar environment are not well-understood, requiring further investigation. To address that we initiated an observing campaign to obtain a homogeneous set of high-resolution spectra in both the optical and NIR (using MPG-ESO/FEROS, GEMINI/Phoenix and VLT/CRIRES, respectively). We monitor a number of Galactic B[e] Supergiants, for which we examined the [OI] and [CaII] emission lines and the bandheads of the CO and SiO molecules to probe the structure and the kinematics of their formation regions. We find that the emission from each tracer forms either in a single or in multiple equatorial rings.

  12. Supergiant fast X-ray transients as an under-luminous class of supergiant X-ray binaries

    CERN Document Server

    Bozzo, E; Ducci, L; Bernardini, F; Falanga, M

    2014-01-01

    The usage of cumulative luminosity distributions, constructed thanks to the long-term observations available through wide field hard X-ray imagers, has been recently exploited to study the averaged high energy emission (>17 keV) from Supergiant Fast X-ray Transients (SFXTs) and classical Supergiant High Mass X-ray Binaries (SgXBs). Here, we take advantage of the long term monitorings now available with Swift/XRT to construct for the first time the cumulative luminosity distributions of a number of SFXTs and the classical SgXB IGR J18027-2016 in the soft X-ray domain with a high sensitivity focusing X-ray telescope (0.3-10 keV). By complementing previous results obtained in the hard X-rays, we found that classical SgXBs are characterized by cumulative distributions with a single knee around $\\sim$10$^{36}$-10$^{37}$ erg/s, while SFXTs are found to be systematically sub-luminous and their distributions are shifted at significantly lower luminosities (a factor of $\\sim$10-100). As the luminosity states in which ...

  13. Clinical epidemiology of human AE in Europe.

    Science.gov (United States)

    Vuitton, D A; Demonmerot, F; Knapp, J; Richou, C; Grenouillet, F; Chauchet, A; Vuitton, L; Bresson-Hadni, S; Millon, L

    2015-10-30

    This review gives a critical update of the situation regarding alveolar echinococcosis (AE) in Europe in humans, based on existing publications and on findings of national and European surveillance systems. All sources point to an increase in human cases of AE in the "historic endemic areas" of Europe, namely Germany, Switzerland, Austria and France and to the emergence of human cases in countries where the disease had never been recognised until the end of the 20th century, especially in central-eastern and Baltic countries. Both increase and emergence could be only due to methodological biases; this point is discussed in the review. One explanation may be given by changes in the animal reservoir of the parasite, Echinococcus multilocularis (increase in the global population of foxes in Europe and its urbanisation, as well as a possible increased involvement of pet animals as definitive infectious hosts). The review also focuses onto 2 more original approaches: (1) how changes in therapeutic attitudes toward malignant and chronic inflammatory diseases may affect the epidemiology of AE in the future in Europe, since a recent survey of such cases in France showed the emergence of AE in patients with immune suppression since the beginning of the 21st century; (2) how setting a network of referral centres in Europe based on common studies on the care management of patients might contribute to a better knowledge of AE epidemiology in the future. PMID:26346900

  14. 22 CFR 120.30 - The Automated Export System (AES).

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of Commerce, Bureau of Census, electronic filing of export information. The AES shall serve as the...

  15. A Survey for a Coeval, Comoving Group Associated with HD 141569

    CERN Document Server

    Aarnio, Alicia N; Stassun, Keivan G; Mamajek, Eric E; James, David J

    2008-01-01

    We present results of a search for a young stellar moving group associated with the star HD 141569, a nearby, isolated Herbig AeBe primary member of a 5+/-3 Myr-old triple star system on the outskirts of the Sco-Cen complex. Our spectroscopic survey identified a population of 21 Li-rich, <30 Myr-old stars within 30 degrees of HD 141569 which possess similar proper motions with the star. The spatial distribution of these Li-rich stars, however, is not suggestive of a moving group associated with the HD 141569 triplet, but rather this sample appears cospatial with Upper Scorpius and Upper Centaurus Lupus. We apply a modified moving cluster parallax method to compare the kinematics of these youthful stars with Upper Scorpius and Upper Centaurus Lupus. Eight new potential members of Upper Scorpius and five new potential members of Upper Centaurus Lupus are identified. A substantial moving group with an identifiable nucleus within 15 degrees (~30 pc) of HD 141569 is not found in this sample. Evidently, the HD 1...

  16. Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1

    CERN Document Server

    Mackey, Jonathan; Fossati, Luca; Langer, Norbert

    2015-01-01

    The massive red supergiant (RSG) W26 in Westerlund 1 is one of a growing number of RSGs shown to have winds that are ionized from the outside in. The fate of this dense wind material is important for models of second generation star formation in massive star clusters. Mackey et al. (2014) showed that external photoionization can stall the wind of RSGs and accumulate mass in a dense static shell. We use 1D R-HD simulations of an externally photoionized wind to predict the Halpha and [NII] emission arising from photoionized winds both with and without a dense shell. We analyse spectra of the Halpha and [NII] emission in the environment around W26 and compare them with predicted synthetic emission. Simulations of slow winds that are decelerated into a dense shell show strongly limb-brightened line emission, with line radial velocities that are independent of the wind speed. Faster winds (>22 km/s) do not form a dense shell, have less limb-brightening, and the line radial velocity is a good tracer of the wind spe...

  17. Detection of a red supergiant progenitor star of a type II-plateau supernova.

    Science.gov (United States)

    Smartt, Stephen J; Maund, Justyn R; Hendry, Margaret A; Tout, Christopher A; Gilmore, Gerard F; Mattila, Seppo; Benn, Chris R

    2004-01-23

    We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion, and subsequent HST images confirm the positional coincidence of the supernova with a single resolved star that is a red supergiant of 8(+4)(-2) solar masses. This confirms both stellar evolution models and supernova theories predicting that cool red supergiants are the immediate progenitor stars of type II-plateau supernovae. PMID:14739452

  18. AES ALGORITHM IMPLEMENTATION IN PROGRAMMING LANGUAGES

    Directory of Open Access Journals (Sweden)

    Luminiţa DEFTA

    2010-12-01

    Full Text Available Information encryption represents the usage of an algorithm to convert an unknown message into an encrypted one. It is used to protect the data against unauthorized access. Protected data can be stored on a media device or can be transmitted through the network. In this paper we describe a concrete implementation of the AES algorithm in the Java programming language (available from Java Development Kit 6 libraries and C (using the OpenSSL library. AES (Advanced Encryption Standard is an asymmetric key encryption algorithm formally adopted by the U.S. government and was elected after a long process of standardization.

  19. Magnetic Fields and Convection in the Cool Supergiant Betelgeuse

    Science.gov (United States)

    Petit, P.; Aurière, M.; Konstantinova-Antova, R.; Morgenthaler, A.; Perrin, G.; Roudier, T.; Donati, J.-F.

    We present the outcome of a highly-sensitive search for magnetic fields on the cool supergiant Betelgeuse. A time-series of six circularly polarized spectra was obtained using the NARVAL spectropolarimeter at Télescope Bernard Lyot (Pic du Midi Observatory (F)), between March and April 2010. Zeeman signatures were repeatedly detected in cross-correlation profiles, corresponding to a longitudinal component of about 1 G. The time-series unveils a smooth increase of the longitudinal field from 0.5 to 1.5 G, correlated with radial velocity fluctuations. We observe a strong asymmetry of Stokes V signatures, also varying in correlation with the radial velocity. The Stokes V line profiles are red-shifted by about 9 km s-1 with respect to the Stokes I profiles, suggesting that the observed magnetic elements may be concentrated in the sinking components of the convective flows.

  20. Long-term spectropolarimetric monitoring of the cool supergiant betelgeuse

    Science.gov (United States)

    Bedecarrax, I.; Petit, P.; Aurière, M.; Grunhut, J.; Wade, G.; Chiavassa, A.; Donati, J.-F.; Konstantinova-Antova, R.; Perrin, G.

    2013-05-01

    We report on a long-term monitoring of the cool supergiant Betelgeuse, using the NARVAL and ESPaDOnS high-resolution spectropolarimeters, respectively installed at Telescope Bernard Lyot (Pic du Midi Observatory, France) and at the Canada-France-Hawaii Telescope (Mauna Kea Observatory, Hawaii). The data set, constituted of circularly polarized (Stokes V) and intensity (Stokes I) spectra, was collected between 2010 and 2012. We investigate here the temporal evolution of magnetic field, convection and temperature at photospheric level, using simultaneous measurements of the longitudinal magnetic field component, the core emission of the Ca II infrared triplet, the line-depth ratio of selected photospheric lines and the radial velocity of the star.

  1. Supergiant fast X-ray transients: the Swift monitoring program

    CERN Document Server

    Romano, P; Cusumano, G; La Parola, V; Kennea, J A; Vercellone, S; Ducci, L; Krimm, H A; Esposito, P; Mangano, V; Paizis, A; Burrows, D N; Gehrels, N

    2010-01-01

    For the first time, Swift is giving us the opportunity to study supergiant fast X-ray transients (SFXTs) throughout all phases of their life: outbursts, intermediate level, and quiescence. We present our intense monitoring of four SFXTs, observed 2-3 times per week since October 2007. We find that, unexpectedly, SFXTs spend most of their time in an intermediate level of accretion ($L_{X}\\sim 10^{33-34} $ erg s$^{-1}$), characterized by rich flaring activity. We present an overview of our investigation on SFXTs with Swift, the key results of our Project. We highlight the unique contribution Swift is giving to this field, both in terms of outburst observations and through a systematic monitoring.

  2. Spectroscopic diagnostics for circumstellar disks of B[e] supergiants

    CERN Document Server

    Kraus, Michaela

    2016-01-01

    B[e] supergiants (B[e]SGs) are emission-line objects, presumably in a short-lived phase in the post-main sequence evolution of massive stars. Their intense infrared excess emission indicates large amounts of warm circumstellar dust, and the stars were longtime assumed to possess an aspherical wind consisting of a classical line-driven wind in polar direction and a dense, slow equatorial wind dubbed outflowing disk. The general properties obtained for these disks are in line with this scenario, although current theories have considerable difficulties reproducing the observed quantities. Therefore, more sophisticated observational constraints are needed. These follow from combined optical and infrared spectroscopic studies, which delivered the surprising result that the circumstellar material of B[e]SGs is concentrated in multiple rings revolving the stars on stable Keplerian orbits. Such a scenario requires new ideas for the formation mechanism, in which pulsations might play an important role.

  3. Spectral type, temperature and evolutionary stage in cool supergiants

    CERN Document Server

    Dorda, Ricardo; González-Fernández, Carlos; Tabernero, Hugo M

    2016-01-01

    In recent years, temperature scales in cool supergiants (CSGs) have been disputed, and the possibility that spectral types (SpTs) do not depend primarily on temperature has been raised. We explore the relations between different observed parameters and the capability of deriving accurate intrinsic stellar parameters from them through the analysis of the largest spectroscopic sample of CSGs to date from SMC and LMC. We explore possible correlations between different observational parameters, also making use of near- and mid-infrared colours and literature on photometric variability. Direct comparison between the behaviour of atomic lines (Fe I, Ti I, and Ca II) in the observed spectra and synthetic atmospheric models provides compelling evidence that effective temperature is the prime underlying variable driving the SpT sequence in CSGs. However, there is a clear correlation between SpT and luminosity, with later ones tending to correspond to more luminous stars with heavier mass loss. The population of CSGs i...

  4. Long-term spectropolarimetric monitoring of the cool supergiant Betelgeuse

    CERN Document Server

    Bedecarrax, I; Aurière, M; Grunhut, J; Wade, G; Chiavassa, A; Donati, J -F; Konstantinova-Antova, R; Perrin, G

    2013-01-01

    We report on a long-term monitoring of the cool supergiant Betelgeuse, using the NARVAL and ESPaDOnS high-resolution spectropolarimeters, respectively installed at Telescope Bernard Lyot (Pic du Midi Observatory, France) and at the Canada-France-Hawaii Telescope (Mauna Kea Observatory, Hawaii). The data set, constituted of circularly polarized (Stokes V) and intensity (Stokes I) spectra, was collected between 2010 and 2012. We investigate here the temporal evolution of magnetic field, convection and temperature at photospheric level, using simultaneous measurements of the longitudinal magnetic field component, the core emission of the Ca II infrared triplet, the line-depth ratio of selected photospheric lines and the radial velocity of the star.

  5. Polarimetry and the Envelopes of Magellanic B[e] Supergiants

    CERN Document Server

    Magalhães, A M; Melgarejo, R; Pereyra, A

    2006-01-01

    We discuss the nature of the circumstellar envelopes around the B[e] supergiants (B[e]SG) in the Magellanic Clouds (MC). Contrary to those in the Galaxy, the MC B[e]SG have a well defined luminosity and can be considered members of a well defined class. We discuss spectroscopy and optical broadband polarimetry and spectropolarimetry data. These data show for the first time detailed changes in the polarization across several spectral features. We show that the envelopes of the B[e]SG are generally variable. Broadband polarimetry data show that the envelopes are definitely non-spherically symmetric and large non-axisymmetric ejections may occur. In addition to that, spectropolarimetry is coming of age as a tool to study the B[e]SG envelope structure.

  6. The polarisation of HD 189733

    CERN Document Server

    Bott, Kimberly; Kedziora-Chudczer, Lucyna; Cotton, Daniel V; Lucas, P W; Marshall, Jonathan P; Hough, J H

    2016-01-01

    We present linear polarization observations of the exoplanet system HD 189733 made with the HIgh Precision Polarimetric Instrument (HIPPI) on the Anglo-Australian Telescope (AAT). The observations have higher precision than any previously reported for this object. They do not show the large amplitude polarization variations reported by Berdyugina et al. 2008 and Berdyugina et al. 2011. Our results are consistent with polarization data presented by Wiktorowicz et al. 2015. A formal least squares fit of a Rayleigh-Lambert model yields a polarization amplitude of 29.4 +/- 15.6 parts-per-million. We observe a background constant level of polarization of ~ 55-70 ppm, which is a little higher than expected for interstellar polarization at the distance of HD 189733.

  7. HD188112: Supernova Ia progenitor?

    CERN Document Server

    Latour, M; Heber, U; Schaffenroth, V

    2015-01-01

    HD188112 is an extremely low mass white dwarf in a close binary system. According to a previous study, the mass of HD188112 is $\\sim$0.24 Msun and a lower limit of 0.73 Msun could be put for the mass of its unseen companion, a compact degenarate object. We used HST STIS spectra to measure the rotational broadening of UV metallic lines in HD188112, in order to put tighter constraints on the mass of its companion. By assuming that the system in is synchronous rotation, we derive a companion mass between 1.05 and 1.25 Msun. We also measure abundances for magnesium, silicon, and iron, respectively log $N$(X)/$N$(H) = $-$6.40, $-$7.25, and $-$5.81. The radial velocities measured from the UV spectra are found to be in very good agreement with the prediction based on the orbital parameters derived in the previous study made a decade ago.

  8. The Multiple System HD 27638

    CERN Document Server

    Torres, G

    2005-01-01

    We report spectroscopic observations of HD 27638B, the secondary in a visual binary in which the physically associated primary (separation approximately 19 arcsec) is a B9V star. The secondary shows strong Li 6708 absorption suggesting youth, and has attracted attention in the past as a candidate post-T Tauri star although this has subsequently been ruled out. It was previously known to be a double-lined spectroscopic binary (F8+G6) with a period of 17.6 days, and to show velocity residuals indicating a more distant massive third companion with a period of at least 8 years. Based on our radial velocity measurements covering more than two cycles of the outer orbit, along with other measurements, we derive an accurate triple orbital solution giving an outer period of 9.447 +/- 0.017 yr. The third object is more massive than either of the other two components of HD 27638B, but is not apparent in the spectra. We derive absolute visual magnitudes and effective temperatures for the three visible stars in HD 27638. ...

  9. An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants

    CERN Document Server

    Shultz, M; Petit, V; Grunhut, J; Neiner, C; Hanes, D

    2013-01-01

    Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution ({\\lambda}/{\\Delta}{\\lambda} {\\sim} 65,000) circular polarization (Stokes V ) spectra of six late B and early A type supergiants ({\\beta} Ori, B8Iae; 4 Lac, B9Iab; {\\eta} Leo, A0Ib; HR1040, A0Ib; {\\alpha} Cyg, A2Iae; {\

  10. Research on propagation law of AE wave in coal seam

    Institute of Scientific and Technical Information of China (English)

    WEN Guang-cai; YANG Hui-ming; ZOU Yin-hui; DONG Guo-wei

    2007-01-01

    Based on mechanism of AE creation, put forward sphere cavity model, and deduced wave Equation of AE wave radiated by the AE source in detail, and analyzed the propagation attenuation law of AE stress wave in coal (rock) strata. Displacement function of AE wave indicates that displacement field can be divided into two parts. Firstly, displacement of particle is approaching to the source intensity function in zone near the AE source. Secondly, in zone far away from the AE source, displacement of particle is approaching to the derivative of source intensity function. AE wave changes gradually in the spreading process, and notable change of the wave form happens when wave propagates far away from the AE source.

  11. HD depletion in starless cores

    OpenAIRE

    Sipilä, O.; Caselli, P.; Harju, J.

    2013-01-01

    Aims: We aim to investigate the abundances of light deuterium-bearing species such as HD, H2D+ and D2H+ in a gas-grain chemical model including an extensive description of deuterium and spin state chemistry, in physical conditions appropriate to the very centers of starless cores. Methods: We combine a gas-grain chemical model with radiative transfer calculations to simulate density and temperature structure in starless cores. The chemical model includes deuterated forms of species with up to...

  12. HD139614: the interferometric case for a group-Ib pre-transitional young disk

    CERN Document Server

    Labadie, Lucas; Kreplin, Alexander; Lopez, Bruno; Wolf, Sebastian; Weigelt, Gerd; Ertel, Steve; Berger, Jean-Philippe; Pott, Jorg-Uwe; Danchi, William C

    2014-01-01

    The Herbig Ae star HD 139614 is a group-Ib object, which featureless SED indicates disk flaring and a possible pre-transitional evolutionary stage. We present mid- and near-IR interferometric results collected with MIDI, AMBER and PIONIER with the aim of constraining the spatial structure of the 0.1-10 AU disk region and assess its possible multi-component structure. A two-component disk model composed of an optically thin 2-AU wide inner disk and an outer temperature-gradient disk starting at 5.6 AU reproduces well the observations. This is an additional argument to the idea that group-I HAeBe inner disks could be already in the disk-clearing transient stage. HD 139614 will become a prime target for mid-IR interferometric imaging with the second-generation instrument MATISSE of the VLTI.

  13. AES Water Architecture Study Interim Results

    Science.gov (United States)

    Sarguisingh, Miriam J.

    2012-01-01

    The mission of the Advanced Exploration System (AES) Water Recovery Project (WRP) is to develop advanced water recovery systems in order to enable NASA human exploration missions beyond low earth orbit (LEO). The primary objective of the AES WRP is to develop water recovery technologies critical to near term missions beyond LEO. The secondary objective is to continue to advance mid-readiness level technologies to support future NASA missions. An effort is being undertaken to establish the architecture for the AES Water Recovery System (WRS) that meets both near and long term objectives. The resultant architecture will be used to guide future technical planning, establish a baseline development roadmap for technology infusion, and establish baseline assumptions for integrated ground and on-orbit environmental control and life support systems (ECLSS) definition. This study is being performed in three phases. Phase I of this study established the scope of the study through definition of the mission requirements and constraints, as well as indentifying all possible WRS configurations that meet the mission requirements. Phase II of this study focused on the near term space exploration objectives by establishing an ISS-derived reference schematic for long-duration (>180 day) in-space habitation. Phase III will focus on the long term space exploration objectives, trading the viable WRS configurations identified in Phase I to identify the ideal exploration WRS. The results of Phases I and II are discussed in this paper.

  14. Acceleration of AES encryption on CUDA GPU

    Directory of Open Access Journals (Sweden)

    Takakazu Kurokawa

    2012-01-01

    Full Text Available

    GPU exhibits the capability for applications with a high level of parallelism despite its low cost. The support of integer and logical instructions by the latest generation of GPUs enables us to implement cipher algorithms more easily. However, decisions such as parallel processing granularity and memory allocation impose a heavy burden on programmers. Therefore, this paper presents results of several experiments that were conducted to elucidate the relation between memory allocation styles of variables of AES and granularity as the parallelism exploited from AES encoding processes using CUDA with an NVIDIA GeForce GTX285 (Nvidia Corp.. Results of these experiments showed that the 16 bytes/thread granularity had the highest performance. It achieved approximately 35 Gbps throughput. It also exhibited differences of memory allocation and granularity effects around 2%–30% for performance in standard implementation. It shows that the decision of granularity and memory allocation is the most important factor for effective processing in AES encryption on GPU. Moreover, implementation with overlapping between processing and data transfer yielded 22.5 Gbps throughput including the data transfer time.

  15. Luminous and Variable Stars in M31 and M33. III. The Yellow and Red Supergiants and Post-Red Supergiant Evolution

    CERN Document Server

    Gordon, Michael S; Jones, Terry J

    2016-01-01

    Recent supernova and transient surveys have revealed an increasing number of non-terminal stellar eruptions. Though the progenitor class of these eruptions includes the most luminous stars, little is known of the pre-supernova mechanics of massive stars in their most evolved state, thus motivating a census of possible progenitors. From surveys of evolved and unstable luminous star populations in nearby galaxies, we select a sample of yellow and red supergiant candidates in M31 and M33 for review of their spectral characteristics and spectral energy distributions. Since the position of intermediate and late-type supergiants on the color-magnitude diagram can be heavily contaminated by foreground dwarfs, we employ spectral classification and multi-band photometry from optical and near-infrared surveys to confirm membership. Based on spectroscopic evidence for mass loss and the presence of circumstellar dust in their SEDs, we find that $30-40\\%$ of the yellow supergiants are likely in a post-red supergiant state...

  16. ALMA detection of the rotating molecular disk wind from the young star HD 163296

    OpenAIRE

    Klaassen, P. D.; Juhasz, A.; Mathews, G. S.; Mottram, J. C.; de Gregorio-Monsalvo, I.; van Dishoeck, E. F.; Takahashi, S.; Akiyama, E.; Chapillon, E.; Espada, D.; Hales, A.; Hogerheijde, M.R.; Rawlings, M.; Schmalzl, M.; Testi, L.

    2013-01-01

    Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew ...

  17. LOCATING PLANETESIMAL BELTS IN THE MULTIPLE-PLANET SYSTEMS HD 128311, HD 202206, HD 82943, AND HR 8799

    International Nuclear Information System (INIS)

    In addition to the Sun, six other stars are known to harbor multiple planets and debris disks: HD 69830, HD 38529, HD 128311, HD 202206, HD 82943, and HR 8799. In this paper, we set constraints on the location of the dust-producing planetesimals around the latter four systems. We use a radiative transfer model to analyze the spectral energy distributions of the dust disks (including two new Spitzer IRS spectra presented in this paper), and a dynamical model to assess the long-term stability of the planetesimals' orbits. As members of a small group of stars that show evidence of harboring a multiple planets and planetesimals, their study can help us learn about the diversity of planetary systems.

  18. Red Supergiants as Cosmic Abundance Probes: The Magellanic Clouds

    CERN Document Server

    Davies, Ben; Gazak, Zach; Plez, Bertrand; Bergemann, Maria; Evans, Chris; Patrick, Lee

    2015-01-01

    Red Supergiants (RSGs) are cool (~4000K), highly luminous stars (L - 10^5 Lsun), and are among the brightest near-infrared (NIR) sources in star-forming galaxies. This makes them powerful probes of the properties of their host galaxies, such as kinematics and chemical abundances. We have developed a technique whereby metallicities of RSGs may be extracted from a narrow spectral window around 1{\\mu}m from only moderate resolution data. The method is therefore extremely efficient, allowing stars at large distances to be studied, and so has tremendous potential for extragalactic abundance work. Here, we present an abundance study of the Large and Small Magellanic Clouds (LMC and SMC respectively) using samples of 9-10 RSGs in each. We find average abundances for the two galaxies of [Z]LMC = -0.37 +/- 0.14 and [Z]SMC = -0.53 +/- 0.16 (with respect to a Solar metallicity of Zsun=0.012). These values are consistent with other studies of young stars in these galaxies, and though our result for the SMC may appear hig...

  19. Blue supergiants as descendants of magnetic main sequence stars

    CERN Document Server

    Petermann, I; Castro, N; Fossati, L

    2015-01-01

    About 10$\\%$ of the massive main sequence stars have recently been found to host a strong, large scale magnetic field. Both, the origin and the evolutionary consequences of these fields are largely unknown. We argue that these fields may be sufficiently strong in the deep interior of the stars to suppress convection near the outer edge of their convective core. We performed parametrised stellar evolution calculations and assumed a reduced size of the convective core for stars in the mass range 16 M$_{\\odot}$ to 28 M$_{\\odot}$ from the zero age main sequence until core carbon depletion. We find that such models avoid the coolest part of the main sequence band, which is usually filled by evolutionary models that include convective core overshooting. Furthermore, our `magnetic' models populate the blue supergiant region during core helium burning, i.e., the post-main sequence gap left by ordinary single star models, and some of them end their life in a position near that of the progenitor of Supernova 1987A in t...

  20. Characterisation of red supergiants in the Gaia spectral range

    CERN Document Server

    Dorda, Ricardo; Negueruela, Ignacio

    2016-01-01

    The infrared Calcium Triplet and its nearby spectral region have been used for spectral and luminosity classification of late-type stars, but the samples of cool supergiants (CSGs) used have been very limited (in size, metallicity range, and spectral types covered). The spectral range of the Gaia Radial Velocity Spectrograph (RVS) covers most of this region but does not reach the main TiO bands in this region, whose depths define the M sequence. We study the behaviour of spectral features around the Calcium Triplet and develop effective criteria to identify and classify CSGs, comparing their efficiency with other methods previously proposed. We measure the main spectral features in a large sample (almost 600) of CSGs from three different galaxies, and we analyse their behaviour through a principal component analysis. Using the principal components, we develop an automatised method to differentiate CSGs from other bright late-type stars, and to classify them. The proposed method identifies a high fraction of t...

  1. Bright Flares in Supergiant Fast X-ray Transients

    CERN Document Server

    Shakura, N; Sidoli, L; Paizis, A

    2014-01-01

    At steady low-luminosity states, Supergiant Fast X-ray Transients (SFXTs) can be at the stage of quasi-spherical settling accretion onto slowly rotating magnetized NS from the OB-companion winds. At this stage, a hot quasi-static shell is formed above the magnetosphere, the plasma entry rate into magnetosphere is controlled by (inefficient) radiative plasma cooling, and the accretion rate onto the NS is suppressed by a factor of \\sim 30 relative to the Bondi-Hoyle-Littleton value. Changes in the local wind velocity and density can only slightly increase the mass accretion rate (a factor of \\sim 10) bringing the system into the Compton cooling dominated regime and led to the production of moderately bright flares (L_x\\lesssim 10^{36} erg/s). To interpret the brightest flares (L_x>10^{36}~erg/s) displayed by the SFXTs, we propose that a larger increase in the mass accretion rate can be produced by sporadic capture of magnetized stellar wind plasma. At sufficiently low accretion rates, magnetic reconnection can ...

  2. HD CCTV联盟设定第一个HD CCTV规范

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    最近,旨在管理与提升HD CCTV设备技术标准的全球安防工业联盟宣布,其组内成员已经认证了1.0版本的HD CCTV规范,并且HD CCTV联盟的会员厂商已经开始生产带有HD CCTV徽标的HD CCTV规范产品。

  3. Supernovae from yellow, blue supergiants: origin and consequences for stellar evolution

    Science.gov (United States)

    Meynet, Georges; Georgy, Cyril; Saio, Hideyuki; Kudritzki, Rolf-Peter; Groh, Jose

    2015-08-01

    A few core collapse supernovae progenitors have been found to be yellow or blue supergiants. We shall discuss possible scenarios involving single and close binary evolution allowing to explain this kind of core collapse supernova progenitors. According to stellar models for both single and close binaries, blue supergiants, at the end of their nuclear lifetimes and thus progenitors of core collapse supernovae, present very different characteristics for what concerns their surface compositions, rotational surface velocities and pulsational properties with respect to blue supergiants in their core helium burning phase. We discuss how the small observed scatter of the flux-weighted gravity-luminosity (FWGL) relation of blue supergiants constrains the evolution of massive stars after the Main-Sequence phase and the nature of the progenitors of supernovae in the mass range between 12 and 40 solar masses. The present day observed surface abundances of blue supergiants, of their pulsational properties, as well as the small scatter of the FWGL relation provide strong constraints on both internal mixing and mass loss in massive stars and therefore on the end point of their evolution.

  4. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    W.; BAUMJOHANN; M.; DUNLOP

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  5. A new processing method for the AE index

    Institute of Scientific and Technical Information of China (English)

    ZHANG LingQian; LIU ZhenXing; MA ZhiWei; W. BAUMJOHANN; WU Jian; M. DUNLOP; SHI JianKui; LU Li; WANG JiYe

    2008-01-01

    In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as e coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index end AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

  6. Disk wind and magnetospheric accretion in emission from the Herbig Ae star MWC 480

    Science.gov (United States)

    Tambovtseva, L. V.; Grinin, V. P.; Potravnov, I. S.; Mkrtichian, D. E.

    2016-09-01

    The young Herbig Ae star MWC 480 (HD 31648) is one of the comprehensively spectroscopically studied stars in the ultraviolet, optical, and infrared spectral ranges. Using non-LTE modeling of its hydrogen spectrum, we have calculated the contribution to the hydrogen emission from such important regions of the circumstellar environment as the disk wind and the magnetosphere. We have used our own observations of the stellar spectrum performed with the 2.4-m telescope at the Thai National Observatory to quantitatively check our theoretical calculations. In addition, all of the visible and infrared spectra available in the literature have been used for a qualitative comparison. The modeling results have revealed a significant role of the magneto-centrifugal disk wind in the formation of atomic hydrogen emission. The cause of the emission line variability in the spectrum ofMWC 480 is discussed.

  7. Chaotic appearance of the AE index

    Science.gov (United States)

    Shan, L.-H.; Hansen, P.; Goertz, C. K.; Smith, R. A.

    1991-01-01

    Results are reported from a stochastic analysis of a 5-day time series of the geomagnetic AE index during an active period. The original data, the power spectrum, and the autocorrelation function are shown, and the steps in the analysis are described in detail. It is found that the autocorrelation time scale is about 50 min, giving a correlation dimension (for the construction of a time series of m-dimensional vectors) of 2.4. This result is consistent with either colored-noise or deterministic-chaos magnetosphere models, indicating the need for further investigation.

  8. BOREAS AES READAC Surface Meteorological Data

    Science.gov (United States)

    Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

    2000-01-01

    Canadian AES personnel collected and processed data related to surface atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from one READAC meteorology station in Hudson Bay, Saskatchewan. Parameters include day, time, type of report, sky condition, visibility, mean sea level pressure, temperature, dewpoint, wind, altimeter, opacity, minimum and maximum visibility, station pressure, minimum and maximum air temperature, a wind group, precipitation, and precipitation in the last hour. The data were collected non-continuously from 24-May-1994 to 20-Sep-1994. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  9. BOREAS AES MARSII Surface Meteorological Data

    Science.gov (United States)

    Atkinson, G. Barrie; Funk, Barry; Hall, Forrest G. (Editor); Knapp, David E. (Editor)

    2000-01-01

    Canadian AES personnel collected several data sets related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from six MARSII meteorology stations in the BOREAS region in Canada. Parameters include site, time, temperature, dewpoint, visibility, wind speed, wind gust, wind direction, two cloud groups, precipitation, and station pressure. Temporally, the data cover the period of May to September 1994. Geo-graphically, the stations are spread across the provinces of Saskatchewan and Manitoba. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  10. Bright flares in supergiant fast X-ray transients

    Science.gov (United States)

    Shakura, N.; Postnov, K.; Sidoli, L.; Paizis, A.

    2014-08-01

    At steady low-luminosity states, supergiant fast X-ray transients (SFXTs) can be at the stage of quasi-spherical settling accretion on to slowly rotating magnetized neutron stars from the OB-companion winds. At this stage, a hot quasi-static shell is formed above the magnetosphere, the plasma entry rate into magnetosphere is controlled by (inefficient) radiative plasma cooling, and the accretion rate on to the neutron star is suppressed by a factor of ˜30 relative to the Bondi-Hoyle-Littleton value. Changes in the local wind velocity and density due to, e.g. clumps, can only slightly increase the mass accretion rate (a factor of ˜10) bringing the system into the Compton-cooling-dominated regime and led to the production of moderately bright flares (Lx ≲ 1036 erg s-1). To interpret the brightest flares (Lx > 1036 erg s-1) displayed by the SFXTs within the quasi-spherical settling accretion regimes, we propose that a larger increase in the mass accretion rate can be produced by sporadic capture of magnetized stellar wind plasma. At sufficiently low accretion rates, magnetic reconnection can enhance the magnetospheric plasma entry rate, resulting in copious production of X-ray photons, strong Compton cooling and ultimately in unstable accretion of the entire shell. A bright flare develops on the free-fall time-scale in the shell, and the typical energy released in an SFXT bright flare corresponds to the mass of the shell. This view is consistent with the energy released in SFXT bright flares (˜1038-1040 erg), their typical dynamic range (˜100) and with the observed dependence of these characteristics on the average unflaring X-ray luminosity of SFXTs. Thus, the flaring behaviour of SFXTs, as opposed to steady HMXBs, may be primarily related to their low X-ray luminosity allowing sporadic magnetic reconnection to occur during magnetized plasma entry into the magnetosphere.

  11. Simulation and Experimental Investigation on the AE Tomography to Improve AE Source Location in the Concrete Structure

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2014-01-01

    Full Text Available Acoustic emission (AE tomography, which is based on the time-travel tomography with AE events as its signal sources, is a new visualization tool for inspecting and locating the internal damages in the structures. In this paper, AE tomography is applied to examine a man-made damage in a typical heterogeneous concrete structure to validate its effectiveness. Firstly, the finite element (ABAQUS/Explicit simulation model of the concrete structure with one damaged circle in its center is built, and the simulated AE signals are obtained to establish the AE tomography. The results show that the damaged circle in the created model can be visualized clearly with the AE tomography in its original location. Secondly, the concrete specimen based on the FE model is fabricated, and the pencil lead break (PLB signal is taken as the exciting source for AE tomography. It is shown that the experimental results have good consistency with the FE simulation results, which also verifies the feasibility of the finite element model for AE tomography. Finally, the damage source location based on AE tomography is compared with the traditional time of arrival (TOA location method, and the better location accuracy is obtained with the AE tomography. The research results indicate that AE tomography has great potential in the application of structure damage detection.

  12. Gas Modelling in the Disc of HD 163296

    Science.gov (United States)

    Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; Martin-Zaidi, C.; Kamp, I.; Pinte, C.; Sandell, G.; Vacca, W. D.; Menard, F.; Mendigutia, I.; Duchene, G.; Dent, W. R. F.; Aresu, G.; Meijerink, R.; Spaans, M.

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry

  13. An M-dwarf star in the transition disk of Herbig HD142527; Physical parameters and orbital elements

    CERN Document Server

    Lacour, S; Cheetham, A; Greenbaum, A; Pearce, T; Marino, S; Tuthill, P; Pueyo, L; Mamajek, E E; Girard, J H; Sivaramakrishnan, A; Bonnefoy, M; Baraffe, I; Chauvin, G; Olofsson, J; Juhasz, A; Benisty, M; Pott, J -U; Sicilia-Aguilar, A; Henning, T; Cardwell, A; Goodsell, S; Graham, J R; Hibon, P; Ingraham, P; Konopacky, Q; Macintosh, B; Oppenheimer, R; Perrin, M; Rantakyrö, F; Sadakuni, N; Thomas, S

    2015-01-01

    HD 142527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of $\\approx20$ in mass ratio between the two objects makes this binary system different from any other YSO. The HD142527 system could therefore provides a valuable testbed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and the dust trapping observed by ALMA at longer distances. We have observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present here the SEDS for HD 142527A and B from the $R$ band up to the $M$ band as well as the orbital motion of HD 142527B ov...

  14. Clumpy wind accretion in supergiant neutron star high mass X-ray binaries

    Science.gov (United States)

    Bozzo, E.; Oskinova, L.; Feldmeier, A.; Falanga, M.

    2016-05-01

    The accretion of the stellar wind material by a compact object represents the main mechanism powering the X-ray emission in classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. In this work we present the first attempt to simulate the accretion process of a fast and dense massive star wind onto a neutron star, taking into account the effects of the centrifugal and magnetic inhibition of accretion ("gating") due to the spin and magnetic field of the compact object. We made use of a radiative hydrodynamical code to model the nonstationary radiatively driven wind of an O-B supergiant star and then place a neutron star characterized by a fixed magnetic field and spin period at a certain distance from the massive companion. Our calculations follow, as a function of time (on a total timescale of several hours), the transitions of the system through all different accretion regimes that are triggered by the intrinsic variations in the density and velocity of the nonstationary wind. The X-ray luminosity released by the system is computed at each time step by taking into account the relevant physical processes occurring in the different accretion regimes. Synthetic lightcurves are derived and qualitatively compared with those observed from classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. Although a number of simplifications are assumed in these calculations, we show that taking into account the effects of the centrifugal and magnetic inhibition of accretion significantly reduces the average X-ray luminosity expected for any neutron star wind-fed binary. The present model calculations suggest that long spin periods and stronger magnetic fields are favored in order to reproduce the peculiar behavior of supergiant fast X-ray transients in the X-ray domain.

  15. Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way

    International Nuclear Information System (INIS)

    In this paper the fundamental properties of the brightest known stars in our Galaxy are determined for future comparison with results for the most luminous stars in other galaxies. The H-R diagrams (M/sub v/ versus spectral type and M/sub bol/ versus log T/sub e/), the luminosities of the brightest stars, and the ratios of blue to red supergiants are all discussed, and a catalog of over 1000 supergiants and O stars in associations and clusters is included at the end of the paper.The ''theoretical'' H-R diagram (M/sub bol/ versus log T/sub e/) reveals a group of superluminous O stars with M/sub bol/ between -12 mag, a lack of evolved supergiants at these very high luminosities, and an apparent upper limit to the luminosities of the later-type supergiants (>B5) near M/sub bol/=-9.5 mag.The most luminous red supergiants have a maximum visual luminosity near M/sub v/approx. =-8 mag, supporting the suggestion by Sandage and Tammann that they are good distance indicators. Excluding the superluminous star Cyg OB 2 No. 12 (M/sub v/approx. =-9.9 mag), the brightest blue stars are found at M/sub v/approx. =-8.5 mag.The variation of the ratio of blue to red supergiants with luminosity is discussed. There is also evidence for a gradient in this ratio with distance from the galactic center, although the results are limited by the incompleteness of the data

  16. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ?

    OpenAIRE

    Alecian, E.; Neiner, C.; Mathis, S.; Catala, C.; Kochukhov, O.; Landstreet, J.; collaboration, the MiMeS

    2013-01-01

    In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman ...

  17. Detailed Abundances of Planet-Hosting Wide Binaries. II. HD80606 + HD80607

    CERN Document Server

    Mack, Claude E; Schuler, Simon C; Hebb, Leslie; Pepper, Joshua A

    2016-01-01

    We present a detailed chemical abundance analysis of 15 elements in the planet-hosting wide binary system HD80606 + HD80607 using Keck/HIRES spectra. As in our previous analysis of the planet-hosting wide binary HD20782 + HD20781, we presume that these two G5 dwarf stars formed together and therefore had identical primordial abundances. In this binary, HD80606 hosts an eccentric ($e\\approx0.93$) giant planet at $\\sim$0.5 AU, but HD80607 has no detected planets. If close-in giant planets on eccentric orbits are efficient at scattering rocky planetary material into their host stars, then HD80606 should show evidence of having accreted rocky material while HD80607 should not. Here we show that the trends of abundance versus element condensation temperature for HD80606 and HD80607 are statistically indistinguishable, corroborating the recent result of Saffe et al. This could suggest that both stars accreted similar amounts of rocky material; indeed, our model for the chemical signature of rocky planet accretion i...

  18. Quantitative Studies of the Optical and UV Spectra of Galactic Early B Supergiants

    Science.gov (United States)

    Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R.

    2008-01-01

    We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0-B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made. Methods. Fundamental parameters (e.g., T(sub eff), log L(sub *), mass-loss rates and CNO abundances) are derived for individual stars using CMFGEN, a nLTE, line-blanketed model atmosphere code. The impact of these newly derived parameters on the Galactic B supergiant Ten scale, mass discrepancy, and wind-momentum luminosity relation is examined. Results. The B supergiant temperature scale derived here shows a reduction of about 1000-3000 K compared to previous results using unblanketed codes. Mass-loss rate estimates are in good agreement with predicted theoretical values, and all of the 20 BO-B5 supergiants analysed show evidence of CNO processing. A mass discrepancy still exists between spectroscopic and evolutionary masses, with the largest discrepancy occuring at log (L/(solar)L approx. 5.4. The observed WLR values calculated for B0-B0.7 supergiants are higher than predicted values, whereas the reverse is true for B1-B5 supergiants. This means that the discrepancy between observed and theoretical values cannot be resolved by adopting clumped (i.e., lower) mass-loss rates as for O stars. The most surprising result is that, although CMFGEN succeeds in reproducing the optical stellar spectrum accurately, it fails to precisely reproduce key UV diagnostics, such as the N v and C IV P Cygni profiles. This problem arises because the models are not ionised enough and fail to reproduce the full extent of the observed absorption trough of the P Cygni profiles. Conclusions. Newly-derived fundamental parameters for early B supergiants are in good agreement with similar work in the field. The most significant discovery, however, is the failure of CMFGEN to predict

  19. What does C II lambda 2325 A emission tell us about chromospheres of red supergiants? - A critical test using Zeta Aurigae-type K supergiants

    Science.gov (United States)

    Schroeder, K.-P.; Reimers, D.; Carpenter, K. G.; Brown, A.

    1988-01-01

    The limitations of the Carpenter et al. (1985) C II intercombination multiplet method of determining the density and geometric extent of red giant chromospheres are presently tested through observation of the C II 2325 A emission of two K-type supergiants whose empirical model chromospheres have been derived by high-resolution IUE observations at eclipse phases. While the observed C II emission fluxes are well reproduced, much of this emission originates in the high-density lower chromosphere.

  20. HD DVD而生——Seastone HD DVD包装盒

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    虽然支持HD DVD的好莱坞制版商还不能透露HD DVD影碟确切的发行日期,但他们的一个合作伙伴公司透露了相关的消息。Seastone、Media Group[海石媒介集团]最近推出了专门针对HD DVD碟片设计的包装盒。

  1. BOREAS AES Campbell Scientific Surface Meteorological Data

    Science.gov (United States)

    Atkinson, G. Barrie; Funk, Barrie; Knapp. David E. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    Canadian AES personnel collected data related to surface and atmospheric meteorological conditions over the BOREAS region. This data set contains 15-minute meteorological data from 14 automated meteorology stations located across the BOREAS region. Included in this data are parameters of date, time, mean sea level pressure, station pressure, temperature, dew point, wind speed, resultant wind speed, resultant wind direction, peak wind, precipitation, maximum temperature in the last hour, minimum temperature in the last hour, pressure tendency, liquid precipitation in the last hour, relative humidity, precipitation from a weighing gauge, and snow depth. Temporally, the data cover the period of August 1993 to December 1996. The data are provided in tabular ASCII files, and are classified as AFM-Staff data.

  2. Acoustic Emissions (AE) Electrical Systems' Health Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Acoustic Emissions (AE) are associated with physical events, such as thermal activity, dielectric breakdown, discharge inception, as well as crack nucleation and...

  3. Two Small Planets Transiting HD 3167

    CERN Document Server

    Vanderburg, Andrew; Duev, Dmitry A; Jensen-Clem, Rebecca; Latham, David W; Mayo, Andrew W; Baranec, Christoph; Berlind, Perry; Kulkarni, Shrinivas; Law, Nicholas M; Nieberding, Megan N; Riddle, Reed; Salama, Maissa

    2016-01-01

    We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R_e and an ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has a radius of 2.9 R_e and orbits its host star every 29.85 days. At a distance of just 45.8 +/- 2.2 pc, HD 3167 is one of the closest and brightest stars hosting multiple transiting planets, making HD 3167 b and c well suited for follow-up observations. The star is chromospherically inactive and slowly rotating, ideal for radial velocity observations to measure the planets' masses. The outer planet is large enough that it likely has a thick gaseous envelope which could be studied via transmission spectroscopy. Planets transiting bright, nearby stars like HD 3167 are valuable objects to study leading up to the launch of the James Webb Space Telescope.

  4. Water ice at the surface of HD 100546 disk

    CERN Document Server

    Honda, M; Takatsuki, S; Inoue, A K; Nakamoto, T; Fukagawa, M; Tamura, M; Terada, H; Takato, N

    2016-01-01

    We made near infrared multicolor imaging observations of a disk around Herbig Be star HD100546 using Gemini/NICI. K (2.2\\,$\\mu$m), H$_2$O ice (3.06\\,$\\mu$m), and L'(3.8\\,$\\mu$m) disk images were obtained and we found the 3.1\\,$\\mu$m absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on \\cite{Oka2012} including water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by the both disk models with/without photodesorption effect within the measurement accuracy, but slightly favors the model with photodesorption effects, implying that the UV photons play an important role on the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement on the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models.

  5. Gas in the protoplanetary disc of HD 169142: Herschel's view

    CERN Document Server

    Meeus, G; Woitke, P; Montesinos, B; Mendigutía, I; Riviere-Marichalar, P; Eiroa, C; Mathews, G S; Vandenbussche, B; Howard, C D; Roberge, A; Sandell, G; Duchêne, G; Ménard, F; Grady, C A; Dent, W R F; Kamp, I; Augereau, J C; Thi, W F; Tilling, I; Alacid, J M; Andrews, S; Ardila, D R; Aresu, G; Barrado, D; Brittain, S; Ciardi, D R; Danchi, W; Fedele, D; de Gregorio-Monsalvo, I; Heras, A; Huelamo, N; Krivov, A; Lebreton, J; Liseau, R; Martin-Zaidi, C; Mora, A; Morales-Calderon, M; Nomura, H; Pantin, E; Pascucci, I; Phillips, N; Podio, L; Poelman, D R; Ramsay, S; Riaz, B; Rice, K; Solano, E; Walker, H; White, G J; Williams, J P; Wright, G

    2010-01-01

    In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the Open Time Key Project GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 micron, [CII] 157.7 micron, CO 72.8 and 90.2 micron, and o-H2O 78.7 and 179.5 micron. We only detect the [OI] 63.2 micron line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and 12/13CO data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ...

  6. LBT Discovery of a Yellow Supergiant Eclipsing Binary in the Dwarf Galaxy Holmberg IX

    CERN Document Server

    Prieto, J L; Kochanek, C S; Weisz, D R; Baruffolo, A; Bechtold, J; Burwitz, V; DeSantis, C; Gallozzi, S; Garnavich, P M; Giallongo, E; Hill, J M; Pogge, R W; Ragazzoni, R; Speziali, R; Thompson, D J; Wagner, R M

    2007-01-01

    In a variability survey of M81 using the Large Binocular Telescope we have discovered a peculiar eclipsing binary (MV ~ -7.1) in the field of the dwarf galaxy Holmberg IX. It has a period of 272 days and the light curve is well-fit by an overcontact model in which both stars are overflowing their Roche lobes. It is composed by two yellow supergiants (V-I ~ 1 mag, T_eff = 4800 K), rather than the far more common red or blue supergiants. Such systems must be rare. While we failed to find any similar systems in the literature, we did, however note a second example. The SMC F0 supergiant R47 is a bright (MV ~ -7.5) periodic variable whose All Sky Automated Survey (ASAS) light curve is well-fit as a contact binary with a 181 day period. We propose that these systems are the progenitors of supernovae like SN 2004et and SN 2006ov, which appeared to have yellow progenitors. The binary interactions (mass transfer, mass loss) limit the size of the supergiant to give it a higher surface temperature than an isolated star...

  7. The Disappearance of the Red Supergiant Progenitor of Supernova 2008bk

    OpenAIRE

    Mattila, Seppo; Smartt, Stephen; Maund, Justyn; Benetti, Stefano; Ergon, Mattias

    2010-01-01

    Massive stars end their lives in spectacular supernova explosions. Identifying the progenitor star is a test of stellar evolution and explosion models. Here we show that the progenitor star of the supernova SN 2008bk has now disappeared, which provides conclusive evidence that this was the death of a red supergiant star.

  8. Spectrum of class-M supergiants in the region lambda lambda 7000-6000 angstrom

    Science.gov (United States)

    Orlov, M. Y.; Rodriguez, M. H.; Shavrina, A. V.

    1973-01-01

    A general description is given of the spectrum of four M-supergiants in the region lambda lambda 7000-6000 A from high-dispersion spectrograms (6 A/mm). The equivalent widths of several hundred lines and depths of some molecular band heads were measured.

  9. A cavity and further radial substructures in the disk around HD~97048

    CERN Document Server

    van der Plas, G; Ménard, F; Casassus, S; Canovas, H; Pinte, C; Maddison, S T; Maaskant, K; Avenhaus, H; Cieza, L; Perez, S; Ubach, C

    2016-01-01

    Context: Gaps, cavities and rings in circumstellar disks are signposts of disk evolution and planet-disk interactions. We follow the recent suggestion that Herbig Ae/Be disks with a flared disk harbour a cavity, and investigate the disk around HD~97048. Aims: We aim to resolve the 34$\\pm$ 4 au central cavity predicted by Maaskant et al. (2013) and to investigate the structure of the disk. Methods: We image the disk around HD~97048 using ALMA at 0.85~mm and 2.94~mm, and ATCA (multiple frequencies) observations. Our observations also include the 12CO J=1-0, 12CO J=3-2 and HCO+ J=4-3 emission lines. Results: A central cavity in the disk around HD~97048 is resolved with a 40-46 au radius. Additional radial structure present in the surface brightness profile can be accounted for either by an opacity gap at ~90 au or by an extra emitting ring at ~150 au. The continuum emission tracing the dust in the disk is detected out to 355 au. The 12CO J=3-2 disk is detected 2.4 times farther out. The 12CO emission can be trac...

  10. Dust and Polycyclic Aromatic Hydrocarbon in the Pre-Transitional Disk around HD 169142

    CERN Document Server

    Seok, Ji Yeon

    2015-01-01

    The pre-transitional disk around the Herbig Ae star HD 169142 shows a complex structure of possible ongoing planet formation in dust thermal emission from the near infrared (IR) to millimeter wavelength range. Also, a distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 $\\mu$m, commonly attributed to polycyclic aromatic hydrocarbons (PAHs), are detected prominently in the HD 169142 disk. We model the spectral energy distribution (SED) as well as the PAH emission features of the HD 169142 disk simultaneously with porous dust and astronomical-PAHs taking into account the spatially resolved disk structure. Our porous dust model consisting of three distinct components that are primarily concentrated in the inner ring, middle ring, and outer disk, respectively, provides an excellent fit to the entire SED, and the PAH model closely reproduces the observed PAH features. The accretion of ice mantles onto porous dust aggregates occurs between ~16 AU and 60 AU, which overlaps with the spatial e...

  11. What causes the large extensions of red-supergiant atmospheres? Comparisons of interferometric observations with 1-D hydrostatic, 3-D convection, and 1-D pulsating model atmospheres

    CERN Document Server

    Arroyo-Torres, B; Chiavassa, A; Scholz, M; Freytag, B; Marcaide, J M; Hauschildt, P H; Wood, P R; Abellan, F J

    2015-01-01

    We present the atmospheric structure and the fundamental parameters of three red supergiants, increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. We carried out spectro-interferometric observations of 3 RSGs in the near-infrared K-band with the VLTI/AMBER instrument at medium spectral resolution. To comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3-D convection, and new 1-D self-excited pulsation models of RSGs. Our near-infrared flux spectra are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict ...

  12. HD 30187 B and HD 39927 B: Two suspected nearby hot subdwarfs in resolved binaries (based on observations made with the ESA Hipparcos satellite)

    DEFF Research Database (Denmark)

    Makarov, V.V.; Fabricius, C.

    1999-01-01

    Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual......Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual...

  13. 山羊草Aegilops kotschyi及其供体种Ae.longissima和Ae.umbellulata的醇溶蛋白研究%Gliadin Variations in Aegilops kotschyi and its Progentiors Ae. longissima and Ae. umbellulata

    Institute of Scientific and Technical Information of China (English)

    李霞; 郑有良; 刘登才; 颜泽洪

    2003-01-01

    采用酸性聚丙烯酰胺凝胶电泳(APAGE)法对11份Aegilops kotschyi及其S1染色体组供体种Ae.longissima2份和U染色体组供体种Ae.umbellulata6份进行了醇溶蛋白位点的研究.结果表明:11份Ae.kotschyi共分离出32条带,31条具有多态性,占96.88%,每份材料可以分离出10~17条谱带,其中仅1条(3.12%)是共有带;11份Ae.kotschyi的遗传距离的变异范围在0~0.704之间,平均为0.409;11份Ae.kotschyi分离出的多数醇溶蛋白谱带均与其染色体组供体种Ae.longissi-ma及Ae.umbellulata相同,但仍有8条谱带未在两供体种中找到;11份Ae.kotschyi的醇溶蛋白多态性(96.88%)明显高于Ae.longissima(52.94%)与Ae.umbellulata(88.89%);11份Ae.kotschyi中有4份表现出了一定的特征带,分析知可能在γ区发生了较大的变异.

  14. HD Radio技术及其应用的思考%HD Radio Technology and Its Application

    Institute of Scientific and Technical Information of China (English)

    李栋

    2007-01-01

    本文简要介绍美国HD Radio技术的发展与应用现状,阐述HD Radio技术系统的原理和特征,包括应用在调频广播中的FM HD Radio和应用在中波广播中的AM HD Radio,并讨论了HD Radio技术的应用问题.

  15. Identifying gaps in flaring Herbig Ae/Be disks using spatially resolved mid-infrared imaging. Are all group I disks transitional?

    CERN Document Server

    Maaskant, K M; Waters, L B F M; Tielens, A G G M; Dominik, C; Min, M; Verhoeff, A; Meeus, G; Ancker, M E van den

    2013-01-01

    *Context The evolution of young massive protoplanetary disks toward planetary systems is expected to include the formation of gaps and the depletion of dust and gas. *Aims A special group of flaring disks around Herbig Ae/Be stars do not show prominent silicate emission features. We focus our attention on four key Herbig Ae/Be stars to understand the structural properties responsible for the absence of silicate feature emission. *Methods We investigate Q- and N-band images taken with Subaru/COMICS, Gemini South/T-ReCS and VLT/VISIR. Our radiative transfer modeling solutions require a separation of inner- and outer- disks by a large gap. From this we characterize the radial density structure of dust and PAHs in the disk. *Results The inner edge of the outer disk has a high surface brightness and a typical temperature between ~100-150 K and therefore dominates the emission in the Q-band. We derive radii of the inner edge of the outer disk of 34, 23, 30 and 63 AU for HD97048, HD169142, HD135344B and Oph IRS 48 r...

  16. Light variations of the blue hypergiants HD 168607 and HD 168625 (1973-1999)

    NARCIS (Netherlands)

    Sterken, C; Arentoft, T; Duerbeck, HW; Brogt, E

    1999-01-01

    Stromgren differential photometry of I-ID 168607 and HD 168625 collected during the previous 27 years is analysed. We bring to an end our quarter of a century monitoring of these objects and conclude that HD 168607 shows typical variability of an uneventful LBV, whereas I-ID 168625 remains to be cla

  17. The nature of the late B-type stars HD 67044 and HD 42035

    CERN Document Server

    Monier, R; Royer, F

    2016-01-01

    While monitoring a sample of apparently slowly rotating superficially normal bright late B and early A stars in the northern hemisphere, we have discovered that HD 67044 and HD 42035, hitherto classified as normal late B-type stars, are actually respectively a new chemically peculiar star and a new spectroscopic binary containing a very slow rotator HD 42035 S with ultra-sharp lines (vsini = 3.7 km/s) and a fast rotator HD 42035 B with broad lines. The lines of Ti, Cr, Mn, Sr, Y, Zr and Ba are conspicuous features in the high resolution SOPHIE spectrum of HD 67044. The HgII line at 3983.93 A is also present as a weak feature. The composite spectrum of HD 42035 is characterised by very sharp lines formed in HD 42035 S superimposed onto the shallow and broad lines of HD 42035 B. These very sharp lines are mostly due to light elements from C to Ni, the only heavy species definitely present are Sr and Ba. Selected lines of 21 chemical elements from He up to Hg have been synthesized using model atmospheres compute...

  18. AES, Automated Construction Cost Estimation System

    International Nuclear Information System (INIS)

    A - Description of program or function: AES (Automated Estimating System) enters and updates the detailed cost, schedule, contingency, and escalation information contained in a typical construction or other project cost estimates. It combines this information to calculate both un-escalated and escalated and cash flow values for the project. These costs can be reported at varying levels of detail. AES differs from previous versions in at least the following ways: The schedule is entered at the WBS-Participant, Activity level - multiple activities can be assigned to each WBS-Participant combination; the spending curve is defined at the schedule activity level and a weighing factor is defined which determines percentage of cost for the WBS-Participant applied to the schedule activity; Schedule by days instead of Fiscal Year/Quarter; Sales Tax is applied at the Line Item Level- a sales tax codes is selected to indicate Material, Large Single Item, or Professional Services; a 'data filter' has been added to allow user to define data the report is to be generated for. B - Method of solution: Average Escalation Rate: The average escalation for a Bill of is calculated in three steps. 1. A table of quarterly escalation factors is calculated based on the base fiscal year and quarter of the project entered in the estimate record and the annual escalation rates entered in the Standard Value File. 2. The percentage distribution of costs by quarter for the Bill of Material is calculated based on the schedule entered and the curve type. 3. The percent in each fiscal year and quarter in the distribution is multiplied by the escalation factor for the fiscal year and quarter. The sum of these results is the average escalation rate for that Bill of Material. Schedule by curve: The allocation of costs to specific time periods is dependent on three inputs, starting schedule date, ending schedule date, and the percentage of costs allocated to each quarter. Contingency Analysis: The

  19. Floorplanning with boundary constraints by using AE-TCG

    Science.gov (United States)

    Li, YiMing; Zhou, MingTian; Li, Yi

    2013-03-01

    It is practical and crucial that a designer will want to control the positions of some modules along the chip boundary in the final packing for I/O connection. To solve the problem we propose an algorithm named Area Estimate Transitive Closure Graphs (AE-TCG). By analyzing the feasible condition of boundary constraints, AE-TCG guarantees that the result of each perturbation is a feasible placement with boundary constraints, and doesn't need to transform the infeasible solution to feasible one. Unlike most of the previous algorithms getting the target area after packing, AE-TCG can satisfy the boundary constraints and estimate the area of feasible placement without packing after random perturbation, then accept the beneficial perturbation. For the property of concentrate itself, AE-TCG is running without Simulated Annealing (SA) process. The experimental results show that AE-TCG is effective and efficient than other algorithms with boundary constraints in commonly used MCNC benchmark circuits.

  20. AES and XPS study of plutonium oxidation

    International Nuclear Information System (INIS)

    The initial oxidation of plutonium metal at 270C has been studied using AES and XPS. Initially a clean plutonium surface was prepared by Ar+ bombardment and 5000C-Ar+ bombardment heat cycles. Changes occurring in the plutonium Auger electron spectra in the energy range of 40 to 120 eV and the 4f/sub 5/2/, 4f/sub 7/2/ (core levels), and 5f, 7s (valence band) XPS peaks were monitored during oxygen exposure (10 to 1.8 x 108 L). Examination of the 4f/sub 7/2/ level revealed two oxidation states which are attributed to a suboxide and PuO2. The 4f/sub 7/2/ binding energies for the two oxidation states and plutonium metal are 426.1, 424.4, and 422.2 eV, respectively. By taking the Auger ratio [0(511 eV)/Pu(317 eV)], it was observed that oxidation proceeded by two steps. In the first step there was a rapid increase of oxygen with the formation of the suboxide. In the second stage, the 0(511 eV)/Pu(317 eV) ratio was constant with conversion of the suboxide to PuO2

  1. Gene flow between wheat and wild relatives: empirical evidence from Aegilops geniculata, Ae. neglecta and Ae. triuncialis.

    Science.gov (United States)

    Arrigo, Nils; Guadagnuolo, Roberto; Lappe, Sylvain; Pasche, Sophie; Parisod, Christian; Felber, François

    2011-09-01

    Gene flow between domesticated species and their wild relatives is receiving growing attention. This study addressed introgression between wheat and natural populations of its wild relatives (Aegilops species). The sampling included 472 individuals, collected from 32 Mediterranean populations of three widespread Aegilops species (Aegilops geniculata, Ae. neglecta and Ae. triuncialis) and compared wheat field borders to areas isolated from agriculture. Individuals were characterized with amplified fragment length polymorphism fingerprinting, analysed through two computational approaches (i.e. Bayesian estimations of admixture and fuzzy clustering), and sequences marking wheat-specific insertions of transposable elements. With this combined approach, we detected substantial gene flow between wheat and Aegilops species. Specifically, Ae. neglecta and Ae. triuncialis showed significantly more admixed individuals close to wheat fields than in locations isolated from agriculture. In contrast, little evidence of gene flow was found in Ae. geniculata. Our results indicated that reproductive barriers have been regularly bypassed during the long history of sympatry between wheat and Aegilops.

  2. Polarized proton and deuteron solid HD targets

    International Nuclear Information System (INIS)

    A decade has now elapsed since HD was proposed as a polarized proton and deuteron target with exceptionally desirable properties. These include a very high free proton proportion, independently polarizable proton and deuteron systems, and a ''frozen-spin'' mode of operation which allows separation of the functions of production and utilization of the highly polarized target. A discussion is given of what can be expected of the polarized HD system right now, without further research. The basic features of solid HD pertinent to its use as a ''frozen-spin'' target are outlined, then a summary is given of the particular experimental results which support the contention that the target will perform successfully, and finally, some feasible operating modes and the expected performances from them are presented

  3. Luminous and Variable Stars in M31 and M33. III. The Yellow and Red Supergiants and Post-red Supergiant Evolution

    Science.gov (United States)

    Gordon, Michael S.; Humphreys, Roberta M.; Jones, Terry J.

    2016-07-01

    Recent supernova (SN) and transient surveys have revealed an increasing number of non-terminal stellar eruptions. Though the progenitor class of these eruptions includes the most luminous stars, little is known of the pre-SN mechanics of massive stars in their most evolved state, thus motivating a census of possible progenitors. From surveys of evolved and unstable luminous star populations in nearby galaxies, we select a sample of yellow and red supergiant (RSG) candidates in M31 and M33 for review of their spectral characteristics and spectral energy distributions (SEDs). Since the position of intermediate- and late-type supergiants on the color-magnitude diagram can be heavily contaminated by foreground dwarfs, we employ spectral classification and multi-band photometry from optical and near-infrared surveys to confirm membership. Based on spectroscopic evidence for mass loss and the presence of circumstellar (CS) dust in their SEDs, we find that 30%-40% of the yellow supergiants are likely in a post-RSG state. Comparison with evolutionary tracks shows that these mass-losing, post-RSGs have initial masses between 20 and 40 M ⊙. More than half of the observed RSGs in M31 and M33 are producing dusty CS ejecta. We also identify two new warm hypergiants in M31, J004621.05+421308.06 and J004051.59+403303.00, both of which are likely in a post-RSG state. Based on observations obtained with the Large Binocular Telescope (LBT), an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.

  4. Measurement of HD concentration by gas chromatography

    International Nuclear Information System (INIS)

    Gas chromatography has been used for the on-line measurement of deuterium hydride (HD) which is used in a Tritium Removal Pilot Facility for the demonstration of the removal of the tritium mainly generated in CANDU reactors. Two methods with different carrier gases, neon and hydrogen, are tested and compared each other. It was showed that both the methods could be possible to measure the concentration of H2 and HD. However, the method with a column packed with alumina showed difficulty in the application due to quite long measurement time and reproducibility. The other method using hydrogen as a carrier gas could measure the concentration accurately within comparably short period

  5. Reconfigurable Secure Video Codec Based on DWT and AES Processor

    Directory of Open Access Journals (Sweden)

    Rached Tourki

    2010-01-01

    Full Text Available In this paper, we proposed a secure video codec based on the discrete wavelet transformation (DWT and the Advanced Encryption Standard (AES processor. Either, use of video coding with DWT or encryption using AES is well known. However, linking these two designs to achieve secure video coding is leading. The contributions of our work are as follows. First, a new method for image and video compression is proposed. This codec is a synthesis of JPEG and JPEG2000,which is implemented using Huffman coding to the JPEG and DWT to the JPEG2000. Furthermore, an improved motion estimation algorithm is proposed. Second, the encryptiondecryption effects are achieved by the AES processor. AES is aim to encrypt group of LL bands. The prominent feature of this method is an encryption of LL bands by AES-128 (128-bit keys, or AES-192 (192-bit keys, or AES-256 (256-bit keys.Third, we focus on a method that implements partial encryption of LL bands. Our approach provides considerable levels of security (key size, partial encryption, mode encryption, and has very limited adverse impact on the compression efficiency. The proposed codec can provide up to 9 cipher schemes within a reasonable software cost. Latency, correlation, PSNR and compression rate results are analyzed and shown.

  6. Characterization of Aes nuclear foci in colorectal cancer cells.

    Science.gov (United States)

    Itatani, Yoshiro; Sonoshita, Masahiro; Kakizaki, Fumihiko; Okawa, Katsuya; Stifani, Stefano; Itoh, Hideaki; Sakai, Yoshiharu; Taketo, M Mark

    2016-01-01

    Amino-terminal enhancer of split (Aes) is a member of Groucho/Transducin-like enhancer (TLE) family. Aes is a recently found metastasis suppressor of colorectal cancer (CRC) that inhibits Notch signalling, and forms nuclear foci together with TLE1. Although some Notch-associated proteins are known to form subnuclear bodies, little is known regarding the dynamics or functions of these structures. Here, we show that Aes nuclear foci in CRC observed under an electron microscope are in a rather amorphous structure, lacking surrounding membrane. Investigation of their behaviour during the cell cycle by time-lapse cinematography showed that Aes nuclear foci dissolve during mitosis and reassemble after completion of cytokinesis. We have also found that heat shock cognate 70 (HSC70) is an essential component of Aes foci. Pharmacological inhibition of the HSC70 ATPase activity with VER155008 reduces Aes focus formation. These results provide insight into the understanding of Aes-mediated inhibition of Notch signalling. PMID:26229111

  7. Geometric Phase Effects in the Ultracold D + HD $\\to$ D + HD and D + HD $\\leftrightarrow$ H + D$_2$ Reactions

    CERN Document Server

    Kendrick, Brian K; Balakrishnan, N

    2016-01-01

    The results of accurate quantum reactive scattering calculations for the D + HD($v=4$, $j=0$) $\\to$ D + HD($v'$, $j'$), D + HD($v=4$, $j=0$) $\\to$ H + D$_2$($v'$, $j'$) and H + D$_2$($v=4$, $j=0$) $\\to$ D + HD($v'$,$j'$) reactions are presented for collision energies between $1\\,\\mu{\\rm K}$ and $100\\,{\\rm K}$. The ${\\it ab\\ initio}$ BKMP2 PES for the ground electronic state of H$_3$ is used and all values of total angular momentum between $J=0-4$ are included. The general vector potential approach is used to include the geometric phase. The rotationally resolved, vibrationally resolved, and total reaction rate coefficients are reported as a function of collision energy. Rotationally resolved differential cross sections are also reported as a function of collision energy and scattering angle. Large geometric phase effects appear in the ultracold reaction rate coefficients which result in a significant enhancement or suppression of the rate coefficient (up to $3$ orders of magnitude) relative to calculations wh...

  8. Novel Frequency Hopping Sequences Generator Based on AES Algorithm

    Institute of Scientific and Technical Information of China (English)

    李振荣; 庄奕琪; 张博; 张超

    2010-01-01

    A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying ...

  9. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES. II. NLTE EFFECTS IN J-BAND SILICON LINES

    Energy Technology Data Exchange (ETDEWEB)

    Bergemann, Maria; Kudritzki, Rolf-Peter; Wuerl, Matthias [Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str.1, D-85741 Garching (Germany); Plez, Bertrand [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS, F-34095 Montpellier (France); Davies, Ben [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Gazak, Zach, E-mail: mbergema@mpa-garching.mpg.de, E-mail: Matthias.Wuerl@physik.uni-muenchen.de, E-mail: kud@ifa.hawaii.edu, E-mail: zgazak@ifa.hawaii.edu, E-mail: bertrand.plez@univ-montp2.fr, E-mail: bdavies@ast.cam.ac.uk [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2013-02-20

    Medium-resolution J-band spectroscopy of individual red supergiant stars is a promising tool to investigate the chemical composition of the young stellar population in star-forming galaxies. As a continuation of recent work on iron and titanium, detailed non-LTE (NLTE) calculations are presented to investigate the influence of NLTE on the formation of silicon lines in the J-band spectra of red supergiants. Substantial effects are found resulting in significantly stronger absorption lines of neutral silicon in NLTE. As a consequence, silicon abundances determined in NLTE are significantly smaller than in local thermodynamic equilibrium (LTE) with the NLTE abundance corrections varying smoothly between -0.4 dex and -0.1 dex for effective temperatures between 3400 K and 4400 K. The effects are largest at low metallicity. The physical reasons behind the NLTE effects and the consequences for extragalactic J-band abundance studies are discussed.

  10. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES. II. NLTE EFFECTS IN J-BAND SILICON LINES

    International Nuclear Information System (INIS)

    Medium-resolution J-band spectroscopy of individual red supergiant stars is a promising tool to investigate the chemical composition of the young stellar population in star-forming galaxies. As a continuation of recent work on iron and titanium, detailed non-LTE (NLTE) calculations are presented to investigate the influence of NLTE on the formation of silicon lines in the J-band spectra of red supergiants. Substantial effects are found resulting in significantly stronger absorption lines of neutral silicon in NLTE. As a consequence, silicon abundances determined in NLTE are significantly smaller than in local thermodynamic equilibrium (LTE) with the NLTE abundance corrections varying smoothly between –0.4 dex and –0.1 dex for effective temperatures between 3400 K and 4400 K. The effects are largest at low metallicity. The physical reasons behind the NLTE effects and the consequences for extragalactic J-band abundance studies are discussed.

  11. Red Supergiant Stars as Cosmic Abundance Probes: II. NLTE Effects in J-band Silicon Lines

    CERN Document Server

    Bergemann, Maria; Wueurl, Matthias; Plez, Bertrand; Davies, Ben; Gazak, Zach

    2012-01-01

    Medium resolution J-band spectroscopy of individual red supergiant stars is a promising tool to investigate the chemical composition of the young stellar population in star forming galaxies. As a continuation of recent work on iron and titanium, detailed non-LTE calculations are presented to investigate the influence of NLTE on the formation of silicon lines in the J-band spectra of red supergiants. Substantial effects are found resulting in significantly stronger absorption lines of neutral silicon in non-LTE. As a consequence, silicon abundances determined in non-LTE are significantly smaller than in LTE with the non-LTE abundance corrections varying smoothly between -0.4 dex to -0.1 dex for effective temperatures between 3400K to 4400K. The effects are largest at low metallicity. The physical reasons behind the non-LTE effects and the consequences for extragalactic J-band abundance studies are discussed.

  12. Semi-analytical Formulas for the Fundamental Parameters of Galactic Early B Supergiants

    Directory of Open Access Journals (Sweden)

    Zaninetti, L.

    2009-12-01

    Full Text Available The publication of new tables of calibration of some fundamental parameters of Galactic B0-B5 supergiants in the two classes $I_mathrm{a}$ and $I_mathrm{b} $ allows to particularize the eight parameters conjecture that model five fundamental parameters. The numerical expressions for visual magnitude, radius, mass, luminosity and surface gravity are derived for supergiants in the range of temperature between 29700 K and 15200 K. The availability of accurate tables of calibration allows us to estimate the efficiency of the derived formulas in reproducing the observed values. The average efficiency of the new formulas, expressed in percent, is 94 for the visual magnitude, 81 for the mass, 96 for the radius, 99 for the logarithm of the luminosity and 97 for the logarithm of the surface gravity.

  13. Radiative hydrodynamics simulations of red supergiant stars. IV gray versus non-gray opacities

    CERN Document Server

    Chiavassa, A; Masseron, T; Plez, B

    2011-01-01

    Red supergiants are massive evolved stars that contribute extensively to the chemical enrichment of our Galaxy. It has been shown that convection in those stars gives rise to large granules that cause surface inhomogeneities and shock waves in the photosphere. The understanding of their dynamics is crucial to unveil the unknown mass-loss mechanism, their chemical composition and stellar parameters. We present a new generation of red supergiants simulations with a more sophisticated opacity treatment done with 3D radiative- hydrodynamics CO5BOLD. In the code, the coupled equations of compressible hydrodynamics and non-local radiation transport are solved in the presence of a spherical potential. The stellar core is replaced by a special spherical inner boundary condition, where the gravitational potential is smoothed and the energy production by fusion is mimicked by a simply producing heat corresponding to the stellar luminosity. The post-processing radiative transfer code OPTIM3D is used to extract spectrosc...

  14. An observational evaluation of magnetic confinement in the winds of BA supergiants

    Science.gov (United States)

    Shultz, M.; Wade, G. A.; Petit, V.; Grunhut, J.; Neiner, C.; Hanes, D.; MiMeS Collaboration

    2014-02-01

    Magnetic wind confinement has been proposed as one explanation for the complex wind structures of supergiant stars of spectral types B and A. Observational investigation of this hypothesis was undertaken using high-resolution (λ/Δλ ˜ 65 000) circular polarization (Stokes V) spectra of six late B- and early A-type supergiants (β Ori, B8Iae; 4 Lac, B9Iab; η Leo, A0Ib; HR1040, A0Ib; α Cyg, A2Iae; ν Cep, A2Iab), obtained with the instruments ESPaDOnS and Narval at the Canada-France-Hawaii Telescope and the Bernard Lyot Telescope. Least-squares deconvolution (LSD) analysis of the Stokes V spectra of all stars yields no evidence of a magnetic field, with best longitudinal field 1σ error bars ranging from ˜0.5 to ˜4.5 G for most stars. Spectrum synthesis analysis of the LSD profiles using Bayesian inference yields an upper limit with 95.4 per cent credibility on the polar strength of the (undetected) surface dipole fields of individual stars ranging from 3 to 30 G. These results strongly suggest that magnetic wind confinement due to organized dipolar magnetic fields is not the origin of the wind variability of BA supergiant stars. Upper limits for magnetic spots may also be inconsistent with magnetic wind confinement in the limit of large spot size and filling factor, depending on the adopted wind parameters. Therefore, if magnetic spots are responsible for the wind variability of BA supergiant stars, they likely occupy a small fraction of the photosphere.

  15. Velocities of relaxation processes and thermochemical equilibrium in cold supergiant atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Grinin, V.P.; Tsymbal, V.V.

    1982-01-01

    The velocities of the main relaxational processes in the atmospheres of cold supergiants are considered. It is shown that the characteristic time of the attainment of the dissociation equilibrium in the upper layers of the atmospheres substantially exceeds the characteristic time of the temperature relaxation. It may lead to the deviations from LTE in the atmospheres of the stars where (quasi) periodical temperature perturbations are taking place. The Mira variables and the related objects belong to such stars.

  16. Periodic Variations in Ultraviolet Spectral Lines of the B0.5 Ib Star HD 64760: Evidence for Corotating Wind Streams Rooted in Surface Variations

    Science.gov (United States)

    Owocki, Stanley P.; Cranmer, Steven R.; Fullerton, Alexander W.

    1995-11-01

    We discuss recently observed periodic modulations in the UV wind lines of the B-type supergiant HD 64760, with a focus on the peculiar, upwardly bowed shape seen in isoflux contours of the absorption variations plotted against velocity and time. We show that this qualitative impression of bowed contours is quantitatively confirmed by a peak in the phase for the associated periodic variation at very nearly the same line position as the apparent bow minimum. The bowed shape is significant because it indicates that wind variations evolve both blueward and redward, i.e., toward both larger and smaller line-of-sight velocities. We show here, however, that these characteristics arise naturally from absorption by strictly accelerating corotating wind streams seen in projection against the stellar disk. The quite good agreement obtained with the observed profile variations provides strong evidence for corotating stream modulations in this wind.

  17. Evidence for Tidal Heating in the Dynamics of LMC Carbon Stars and Red Supergiants

    Science.gov (United States)

    Olsen, Knut A.; Massey, P.

    2006-12-01

    We present an analysis of the kinematics of the HI gas, carbon stars, and red supergiants of the Large Magellanic Cloud. After correcting the line-of-sight velocities for the recent accurate measurement of the LMC's space motion, we find that each kinematic tracer clearly defines a flat rotation curve with similar shape but different amplitude for each tracer: 61 km s-1 for the carbon stars, 80 km s-1 for the HI gas, and 107 km s-1 for the red supergiants. We suggest that noncircular motions of the stars and gas in the LMC can at least in part explain the different rotation amplitudes. A significant fraction, 7-15%, of the total sample of carbon stars appears to be associated with previously identified tidal HI streamers. In addition, although the local velocity dispersion of the red supergiants is small, 8 km s-1, their velocity dispersion about the carbon star rotation solution is 17 km s-1, equal to the velocity dispersion of the carbon stars themselves. We thus appear to be witnessing the tidal heating of the LMC's stellar populations.

  18. The evolution of Red Supergiants to supernova in the LMC cluster NGC 2100

    CERN Document Server

    Beasor, Emma R

    2016-01-01

    The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion. To study how mass-loss rates change with evolution we measure the mass-loss rates (\\mdot) and extinctions of 19 red supergiants in the young massive cluster NGC2100 in the Large Magellanic Cloud. By targeting stars in a coeval cluster we can study the mass-loss rate evolution whilst keeping the variables of mass and metallicity fixed. Mass-loss rates were determined by fitting DUSTY models to mid-IR photometry from WISE and Spitzer/IRAC. We find that the \\mdot\\ in red supergiants increases as the star evolves, and is well described by \\mdot\\ prescription of de Jager, used widely in stellar evolution calculations. We find the extinction caused by the warm dust is negligible, meaning the warm circumstellar material of the inner wind cannot explain the higher levels of extinction found in the RSGs compared to other cluster stars. We discuss the implications of this work in...

  19. Clumpy wind accretion in supergiant neutron star high mass X-ray binaries

    CERN Document Server

    Bozzo, E; Feldmeier, A; Falanga, M

    2016-01-01

    The accretion of the stellar wind material by a compact object represents the main mechanism powering the X-ray emission in classical supergiant high mass X-ray binaries and supergiant fast X-ray transients. In this work we present the first attempt to simulate the accretion process of a fast and dense massive star wind onto a neutron star, taking into account the effects of the centrifugal and magnetic inhibition of accretion ("gating") due to the spin and magnetic field of the compact object. We made use of a radiative hydrodynamical code to model the non-stationary radiatively driven wind of an O-B supergiant star and then place a neutron star characterized by a fixed magnetic field and spin period at a certain distance from the massive companion. Our calculations follow, as a function of time (on a total time scale of several hours), the transition of the system through all different accretion regimes that are triggered by the intrinsic variations in the density and velocity of the non-stationary wind. Th...

  20. Probing the structure and dynamics of B[e] supergiant stars' disks

    Science.gov (United States)

    Kraus, M.

    2016-08-01

    B[e] supergiants are a group of evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulates in a circumstellar ring or disk-like structure, revolving around the star on Keplerian orbits. In most objects, the disks seem to be stable over many decades. This guarantees these disks as ideal chemical laboratories to study molecule formation and dust condensation. Combining high-resolution optical and infrared spectroscopic data allows to search for emission features that trace the disk structure, kinematics, and chemical composition at different distances from the star. Certain forbidden emission lines of singly ionized or neutral metals, such as [Caii] and [Oi], are ideal tracers for the innermost gaseous (atomic) regions. Farther out, molecules form. While first-overtone bands of carbon monoxide (CO) mark the hot, inner rim of the molecular disk, more molecules are expected to form and to fill the space between the CO emitting region and the dust condensation zone. Observing campaigns have been initiated to search for these molecules and their emission features, in order to construct a global picture of the properties of the disks around B[e] supergiants. This paper presents an overview of the status of our knowledge about the structure and kinematics of B[e] supergiant stars' disks, based on currently available information from different observational tracers.

  1. Water vapor on supergiants. The 12 micron TEXES spectra of mu Cephei

    CERN Document Server

    Ryde, N; Harper, G M; Lambert, D L; Richter, M J

    2006-01-01

    Several recent papers have argued for warm, semi-detached, molecular layers surrounding red giant and supergiant stars, a concept known as a MOLsphere. Spectroscopic and interferometric analyses have often corroborated this general picture. Here, we present high-resolution spectroscopic data of pure rotational lines of water vapor at 12 microns for the supergiant mu Cephei. This star has often been used to test the concept of molecular layers around supergiants. Given the prediction of an isothermal, optically thick water-vapor layer in Local Thermodynamic Equilibrium around the star (MOLsphere), we expected the 12 micron lines to be in emission or at least in absorption but filled in by emission from the molecular layer around the star. Our data, however, show the contrary; we find definite absorption. Thus, our data do not easily fit into the suggested isothermal MOLsphere scenario. The 12 micron lines, therefore, put new, strong constraints on the MOLsphere concept and on the nature of water seen in signat...

  2. A Habitable Planet around HD 85512?

    CERN Document Server

    Kaltenegger, L; Pepe, F

    2011-01-01

    Aims: In this study we assess the habitability of HD85512b, a 3.6M_Earth planet orbiting a K5V star. The radial velocity data and orbital parameters for HD 85512 b have just been published, based on data from the dedicated HARPS-upgrade GTO program. Methods: This paper outlines a simple approach to evaluate habitability of rocky planets from radial velocity (RV) searches by using atmospheric models of rocky planets with H2O/CO2/N2 atmospheres, like Earth. We focus our analysis on HD 85512 b. To first order the limits of the Habitable Zone depend on the effective stellar flux distribution in wavelength and time, the planet's Bond albedo, and greenhouse gas effects in this approach. We also discuss the dependence of habitability on the measurement accuracies. Results: We provide a simple set of parameters which can be used for evaluating current and future planet candidates from RV searches for their potential habitability. We find that HD 85512 b could be potentially habitable if the planet exhibits more than ...

  3. Hegel HD25解码器

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    来自挪威的Hegel(音乐哲学)推出HD25高级解码器,这款全新的解码器集合了HDll和HD20的经验,专门对电脑音频文件解码进行升级和改造,在采取“即插即用”方式下连接电脑时,HD25能达到24bid96kHz解码能力:当安装专门开发的第三方驱动后,HD25则能支持24bit/192kHz高清音频文件解码播放,当中配备多组数字滤波器,用家可以根据不同的音色喜好来选择。

  4. Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314

    CERN Document Server

    Sato, Bun'ei; Liu, Yujuan; Harakawa, Hiroki; Izumiura, Hideyuki; Kambe, Eiji; Toyota, Eri; Murata, Daisuke; Lee, Byeong-Cheol; Masuda, Seiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro; Ida, Shigeru; Zhao, Gang; Han, Inwoo

    2010-01-01

    We report the detections of two substellar companions orbiting around evolved intermediate-mass stars from precise Doppler measurements at Subaru Telescope and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of 1.9 M_sun and has a planet of minimum mass m_2sini=2.9 M_J orbiting with period of P=176 d and eccentricity of e=0.11. HD 180314 is also a K0 giant with 2.6 M_sun and hosts a substellar companion of m_2sin i=22 M_J, which falls in brown-dwarf mass regime, in an orbit with P=396 d and e=0.26. HD 145457 b is one of the innermost planets and HD 180314 b is the seventh candidate of brown-dwarf-mass companion found around intermediate-mass evolved stars.

  5. Preflight and Inflight Calibration of TES and AES

    Science.gov (United States)

    Rider, David M.

    1997-01-01

    The Thermal Emission Spectrometer (TES), an EOS CHEM platform instrument, and its companion instrument, the Airborne Emission Spectrometer (AES), are both Fourier transform spectrometers designed for remote sensing of the troposphere.

  6. Slowly rotating black holes in Einstein-{\\ae}ther theory

    CERN Document Server

    Barausse, Enrico; Vega, Ian

    2015-01-01

    We study slowly rotating, asymptotically flat black holes in Einstein-\\ae ther theory and show that solutions that are free from naked finite area singularities form a two-parameter family. These parameters can be thought of as the mass and angular momentum of the black hole, while there are no independent \\ae ther charges. We also show that the \\ae ther has non-vanishing vorticity throughout the spacetime, as a result of which there is no hypersurface that resembles the universal horizon found in static, spherically symmetric solutions. Moreover, for experimentally viable choices of the coupling constants, the frame-dragging potential of our solutions only shows percent-level deviations from the corresponding quantities in General Relativity and Horava gravity. Finally, we uncover and discuss several subtleties in the correspondence between Einstein-\\ae ther theory and Horava gravity solutions in the $c_\\omega\\to\\infty$ limit.

  7. The mineral clouds on HD 209458b and HD 189733b

    Science.gov (United States)

    Helling, Ch.; Lee, G.; Dobbs-Dixon, I.; Mayne, N.; Amundsen, D. S.; Khaimova, J.; Unger, A. A.; Manners, J.; Acreman, D.; Smith, C.

    2016-07-01

    3D atmosphere model results are used to comparatively study the kinetic, non-equilibrium cloud formation in the atmospheres of two example planets guided by the giant gas planets HD 209458b and HD 189733b. Rather independently of hydrodynamic model differences, our cloud modelling suggest that both planets are covered in mineral clouds throughout the entire modelling domain. Both planets harbour chemically complex clouds that are made of mineral particles that have a height-dependent material composition and size. The remaining gas-phase element abundances strongly affect the molecular abundances of the atmosphere in the cloud-forming regions. Hydrocarbon and cyanopolyyne molecules can be rather abundant in the inner, dense part of the atmospheres of HD 189733b and HD 209458b. No one value for metallicity and the C/O ratio can be used to describe an extrasolar planet. Our results concerning the presence and location of water in relation to the clouds explain some of the observed difference between the two planets. In HD 189733b, strong water features have been reported while such features appear less strong for HD 209458b. By considering the location of the clouds in the two atmospheres, we see that obscuring clouds exist high in the atmosphere of HD 209458b, but much deeper in HD 189733b. We further conclude that the (self-imposed) degeneracy of cloud parameters in retrieval methods can only be lifted if the cloud formation processes are accurately modelled in contrast to prescribing them by independent parameters.

  8. Photometric Observations of Two Cool Stars: HD 17025 and HD 38392

    Science.gov (United States)

    Stȩpień, K.

    1995-07-01

    UBV(RI)c observations of a G6/G8IV star HD17025 suggest a variation period of about 9 days. The light curve has a marginal amplitude of about 0.015 of a magnitude but is poorly defined and needs an independent confirmation. No prominent chromospheric emission is visible in a spectrum of this star. The other observed star, a K2 dwarf HD38392, did not show measurable light variations over a two weeks period of observations.

  9. Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509

    CERN Document Server

    Wittrock, Justin M; Horch, Elliott P; Hirsch, Lea; Howell, Steve B; Ciardi, David R; Everett, Mark E; Teske, Johanna K

    2016-01-01

    An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 nm and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD 2638 and HD 164509. The stellar companion to HD 2638 has been previously detected, but the companion to HD 164509 is a newly discovered companion. The angular separation for HD 2638 is $0.512 \\pm 0.002\\arcsec$ and for HD 164509 is $0.697 \\pm 0.002\\arcsec$. This corresponds to a projected separation of $25.6 \\pm 1.9$ AU and $36.5 \\pm 1.9$ AU, respectively. By employing stellar isochrone models, we e...

  10. JVC公司在广州发布Full HD HD-ILA&Sophisti影音新品

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    12月12日,JVC 2006-2007年度Full HD HD-ILA&Sophisti影音新品发布会在广州江湾酒店隆重举行,JVC公司推出了一系列新品,包括多款超大屏幕FullHD HD-ILA“真高清”光硅晶电视以及全新的Sophisti家庭影院系统。

  11. Gene flow between wheat and wild relatives: empirical evidence from Aegilops geniculata, Ae. neglecta and Ae. triuncialis

    OpenAIRE

    Arrigo, Nils; Guadagnuolo, Roberto; Lappe, Sylvain; Pasche, Sophie; Parisod, Christian; Felber, François

    2011-01-01

    Gene flow between domesticated species and their wild relatives is receiving growing attention. This study addressed introgression between wheat and natural populations of its wild relatives (Aegilops species). The sampling included 472 individuals, collected from 32 Mediterranean populations of three widespread Aegilops species (Aegilops geniculata, Ae. neglecta and Ae. triuncialis) and compared wheat field borders to areas isolated from agriculture. Individuals were characterized with ampli...

  12. Search for exoplanet around northern circumpolar stars - Four planets around HD 11755, HD 12648, HD 24064, and 8 Ursae Minoris

    CERN Document Server

    Lee, B -C; Lee, S -M; Jeong, G; Oh, H -I; Han, I; Lee, J W; Lee, C -U; Kim, S -L; Kim, K -M

    2015-01-01

    Aims. This program originated as the north pole region extension of the established exoplanet survey using 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). The aim of our paper is to find exoplanets in northern circumpolar stars with a precise radial velocity (RV) survey. Methods. We have selected about 200 northern circumpolar stars with the following criteria: Dec. > 70 degree, 0.6 < B-V < 1.6, HIPPARCOS_scat < 0.05 magnitude, and 5.0 < mv < 7.0. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used for the RV survey. Chromospheric activities, the HIPPARCOS photometry, and line bisectors were analyzed to exclude other causes for the RV variations. Results. In 2010, we started to monitor the candidates and have completed initial screening for all stars for the last five years. We present the detection of four new exoplanets. Stars HD 11755, HD 12648, HD 24064, and 8 UMi all show evidence for giant planets in Keplerian motion. The companion ...

  13. Combinations of Hd2 and Hd4 genes determine rice adaptability to Heilongjiang Province, northern limit of China

    Institute of Scientific and Technical Information of China (English)

    Xiufeng Li; Jun Fang; Qingyun Bu; Huazhao Liu; Maoqing Wang; Hualong Liu; Xiaojie Tian; Wenjia Zhou; Tianxiao L; Zhenyu Wang; Chengcai Chu

    2015-01-01

    Heading date is a key trait in rice domestication and adaption, and a number of quantitative trait loci (QTLs) have been identified. The rice (Oryza sativa L.) cultivars in the Heilongjiang Province, the northernmost region of China, have to flower extremely early to fulfill their life cycle. However, the critical genes or different gene combinations controlling early flowering in this region have not been determined. QTL and candidate gene analysis revealed that Hd2/Ghd7.1/OsPRR37 plays a major role in controlling rice distribution in Heilongjiang. Further association analysis with a collection of rice cultivars demonstrated that another three major QTL genes (Hd4/Ghd7, Hd5/DTH8/Ghd8, and Hd1) also participate in regulating heading date under natural long day (LD) conditions. Hd2/Ghd7.1/OsPRR37 and Hd4/Ghd7 are two major QTLs and function additively. With the northward rice cultivation, the Hd2/Ghd7.1/OsPRR37 and Hd4/Ghd7 haplotypes became non-functional alleles. Hd1 might be non-functional in most Heilongjiang rice varieties, implying that recessive hd1 were selected during local rice breeding. Non-functional Hd5/DTH8/Ghd8 is very rare, but constitutes a potential target for breeding extremely early flowering cultivars. Our results indicated that diverse genetic combinations of Hd1, Hd2, Hd4, and Hd5 determined the different distribution of rice varieties in this northernmost province of China.

  14. HD DVD全国首家深度报道:TOSHIBA HD-A1 HD DVD播放机

    Institute of Scientific and Technical Information of China (English)

    Firewan; 游宇(PHOTO)

    2006-01-01

    早在今年3月,东芝就推出了首款HD DVD播放机,可惜一直未在国内上市。国内一位资深玩家从美国辗转带回一台东芝HD-A1 HD DVD播放机,终于让我们也能够首次品尝HD DVD带来的高清体验。

  15. The SPHERE view of the planet-forming disk around HD100546

    CERN Document Server

    Garufi, Antonio; Schmid, Hans Martin; Mulders, Gijs D; Avenhaus, Henning; Boccaletti, Anthony; Ginski, Christian; Langlois, Maud; Stolker, Tomas; Augereau, Jean-Charles; Benisty, Myriam; Lopez, Bruno; Dominik, Carsten; Gratton, Raffaele; Henning, Thomas; Janson, Markus; Menard, Francois; Meyer, Michael R; Pinte, Christophe; Sissa, Elena; Vigan, Arthur; Zurlo, Alice; Bazzon, Andreas; Buenzli, Esther; Bonnefoy, Mickael; Brandner, Wolfgang; Chauvin, Gael; Cheetham, Anthony; Cudel, Maxime; Desidera, Silvano; Feldt, Markus; Galicher, Raphael; Kasper, Markus; Lagrange, Anne-Marie; Lannier, Justine; Maire, Anne-Lise; Mesa, Dino; Mouillet, David; Peretti, Sebastien; Perrot, Clement; Salter, Graeme; Wildi, Francois

    2016-01-01

    We image with unprecedented spatial resolution and sensitivity disk features that could be potential signs of planet-disk interaction. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD100546 in scattered light. We obtain the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyze with the Pynpoint package. The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to ADI processing) resembles a morphology newly observed in inclined disks. Given the cav...

  16. Formation of the resonant system HD 60532

    CERN Document Server

    Sandor, Zsolt

    2010-01-01

    Among multi-planet planetary systems there are a large fraction of resonant systems. Studying the dynamics and formation of these systems can provide valuable informations on processes taking place in protoplanetary disks where the planets are thought have been formed. The recently discovered resonant system HD 60532 is the only confirmed case, in which the central star hosts a pair of giant planets in 3:1 mean motion resonance. We intend to provide a physical scenario for the formation of HD 60532, which is consistent with the orbital solutions derived from the radial velocity measurements. Observations indicate that the system is in an antisymmetric configuration, while previous theoretical investigations indicate an asymmetric equilibrium state. The paper aims at answering this discrepancy as well. We performed two-dimensional hydrodynamical simulations of thin disks with an embedded pair of massive planets. Additionally, migration and resonant capture are studied by gravitational N-body simulations that a...

  17. Characterization of depression in prodromal Huntington disease in the neurobiological predictors of HD (PREDICT-HD) study.

    Science.gov (United States)

    Epping, Eric A; Mills, James A; Beglinger, Leigh J; Fiedorowicz, Jess G; Craufurd, David; Smith, Megan M; Groves, Mark; Bijanki, Kelly R; Downing, Nancy; Williams, Janet K; Long, Jeffrey D; Paulsen, Jane S

    2013-10-01

    Depression causes significant morbidity and mortality, and this also occurs in Huntington Disease (HD), an inherited neurodegenerative illness with motor, cognitive, and psychiatric symptoms. The presentation of depression in this population remains poorly understood, particularly in the prodromal period before development of significant motor symptoms. In this study, we assessed depressive symptoms in a sample of 803 individuals with the HD mutation in the prodromal stage and 223 mutation-negative participants at the time of entry in the Neurobiological Predictors of HD (PREDICT-HD) study. Clinical and biological HD variables potentially related to severity of depression were analyzed. A factor analysis was conducted to characterize the symptom domains of depression in a subset (n=168) with clinically significant depressive symptoms. Depressive symptoms were found to be more prevalent in HD mutation carriers but did not increase with proximity to HD diagnosis and were not associated with length of the HD mutation. Increased depressive symptoms were significantly associated with female gender, self-report of past history of depression, and a slight decrease in functioning, but not with time since genetic testing. The factor analysis identified symptom domains similar to prior studies in other populations. These results show that individuals with the HD mutation are at increased risk to develop depressive symptoms at any time during the HD prodrome. The clinical presentation appears to be similar to other populations. Severity and progression are not related to the HD mutation.

  18. 可兼容AES-128、AES-192、AES-256串行AES加密解密电路设计%Compatible AES-128、AES-192、AES-256 Serial AES Encryption and Decryption Circuit Design

    Institute of Scientific and Technical Information of China (English)

    韩少男; 李晓江

    2010-01-01

    通过分析AES算法的基本原理,对算法中的AES-128、AES-192、AES-256三种不同的加密解密模式进行了综合设计,有效地利用了公共模块,与单个分别实施各个加密解密模式相比,大大减少了硬件电路面积.针对目前AES实现方法中的key产生模块进行了理论分析,提出了一种新的实现电路结构.设计出的串行AES硬件加密解密电路经综合后得到的芯片面积为31 286门,最高工作频率为66MHz,可以满足目前的大部分无线传感网络的数据交换速率的需求.

  19. 77 FR 15098 - AES Hawaii, Inc.; Notice of Petition for Temporary Waiver

    Science.gov (United States)

    2012-03-14

    ... Energy Regulatory Commission AES Hawaii, Inc.; Notice of Petition for Temporary Waiver Take notice that... (Commission) Rules of Practice and Procedure, 18 CFR 292.205(c), AES Hawaii, Inc. (AES Hawaii) filed a Request... on the island of Oauh, Hawaii. AES Hawaii makes such a request because of a forced boiler outage...

  20. 76 FR 1427 - AES Wind Generation, Inc. v. California Independent System Operator Corporation; Notice of...

    Science.gov (United States)

    2011-01-10

    ... Energy Regulatory Commission AES Wind Generation, Inc. v. California Independent System Operator..., 2011. Take notice that on December 30, 2010, AES Wind Generation, Inc. (AES Wind), pursuant to Rule 206...), concerning the requirement that AES Wind post its second financial security for transmission...

  1. An M-dwarf star in the transition disk of Herbig HD 142527. Physical parameters and orbital elements

    Science.gov (United States)

    Lacour, S.; Biller, B.; Cheetham, A.; Greenbaum, A.; Pearce, T.; Marino, S.; Tuthill, P.; Pueyo, L.; Mamajek, E. E.; Girard, J. H.; Sivaramakrishnan, A.; Bonnefoy, M.; Baraffe, I.; Chauvin, G.; Olofsson, J.; Juhasz, A.; Benisty, M.; Pott, J.-U.; Sicilia-Aguilar, A.; Henning, T.; Cardwell, A.; Goodsell, S.; Graham, J. R.; Hibon, P.; Ingraham, P.; Konopacky, Q.; Macintosh, B.; Oppenheimer, R.; Perrin, M.; Rantakyrö, F.; Sadakuni, N.; Thomas, S.

    2016-05-01

    Aims: HD 42527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of ≈20 in mass ratio between the two objects makes this binary system different from any other YSO. The HD 142527 system could therefore provide a valuable test bed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and dust trapping observed by ALMA at longer distances. Methods: We observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present the spectral energy distribution (SED) for HD 142527A and B. Brightness of the companion is now known from the R band up to the M' band. We also followed the orbital motion of HD 142527B over a period of more than two years. Results: The SED of the companion is compatible with a T = 3000 ± 100 K object in addition to a 1700 K blackbody environment (likely a circum-secondary disk). From evolution models, we find that it is compatible with an object of mass 0.13 ± 0.03 M⊙, radius 0.90 ± 0.15 R⊙, and age Myr. This age is significantly younger than the age previously estimated for HD 142527A. Computations to constrain the orbital parameters found a semimajor axis of mas, an eccentricity of 0.5 ± 0.2, an inclination of 125 ± 15 degrees, and a position angle of the right ascending node of -5 ± 40 degrees. Inclination and position angle of the ascending node are in agreement with an orbit coplanar with the inner disk, not coplanar with the outer disk. Despite its high eccentricity, it is unlikely that HD 142527B is responsible for truncating the inner edge of the outer disk.

  2. X-ray Pulsations from the region of the Supergiant Fast X-ray Transient IGR J17544-2619

    CERN Document Server

    Drave, S P; Townsend, L J; Hill, A B; McBride, V A; Sguera, V; Bazzano, A; Clark, D J

    2012-01-01

    Phase-targeted RXTE observations have allowed us to detect a transient 71.49 \\pm 0.02 s signal that is most likely to be originating from the supergiant fast X-ray transient IGR J17544-2619. The phase-folded light curve shows a possible double-peaked structure with a pulsed flux of ~4.8*10^-12 erg cm^-2 s^-1 (3-10 keV). Assuming the signal to indicate the spin period of the neutron star in the system, the provisional location of IGR J17544-2619 on the Corbet diagram places the system within the classical wind-fed supergiant XRB region. Such a result illustrates the growing trend of supergiant fast X-ray transients to span across both of the original classes of HMXB in Porb - Pspin space.

  3. Resolving the inner regions of the HD97048 circumstellar disk with VLT/NACO polarimetric differential imaging

    CERN Document Server

    Quanz, Sascha P; Apai, Daniel; Wolf, Sebastian; Henning, Thomas

    2011-01-01

    Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. As most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disk on these scales to constrain the conditions for planet formation. Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD97048 in polarized light. We use VLT/NACO to observe HD97048 in polarimetric differential imaging (PDI) mode in the H and Ks band. We spatially resolve the disk around HD97048 in polarized flux in both filters on scales between ~0.1"-1.0" corresponding to the inner ~16-160 AU. Fitting isophots to the flux calibrated H-band image between 13 - 14 mag/arcsec^2 and 14 - 15 mag/arcsec^2 we derive a apparent disk inclination angle of 34+-5 deg and 47+-2 deg, respectively. The disk position angle in both brightness regimes is almost identical and roughly 80 deg. Along...

  4. A model with nonzero rise time for AE signals

    Indian Academy of Sciences (India)

    M A Majeed; C R L Murthy

    2001-10-01

    Acoustic emission (AE) signals are conventionally modelled as damped or decaying sinusoidal functions. A major drawback of this model is its negligible or zero rise time. This paper proposes an alternative model, which provides for the rising part of the signal without sacrificing the analytical tractability and simplicity of the conventional model. Signals obtained from the proposed model through computer programs are illustrated for demonstrating their parity with actual AE signals. Analytic expressions for the time-domain parameters, viz., peak amplitude and rise time used in conventional AE signal analysis, are also derived. The model is believed to be also of use in modelling the output signal of any transducer that has finite rise time and fall time.

  5. Shaft Crack Identification Based on Vibration and AE Signals

    Directory of Open Access Journals (Sweden)

    Wenxiu Lu

    2011-01-01

    Full Text Available The shaft crack is one of the main serious malfunctions that often occur in rotating machinery. However, it is difficult to locate the crack and determine the depth of the crack. In this paper, the acoustic emission (AE signal and vibration response are used to diagnose the crack. The wavelet transform is applied to AE signal to decompose into a series of time-domain signals, each of which covers a specific octave frequency band. Then an improved union method based on threshold and cross-correlation method is applied to detect the location of the shaft crack. The finite element method is used to build the model of the cracked rotor, and the crack depth is identified by comparing the vibration response of experiment and simulation. The experimental results show that the AE signal is effective and convenient to locate the shaft crack, and the vibration signal is feasible to determine the depth of shaft crack.

  6. Meteosat Images Encryption based on AES and RSA Algorithms

    Directory of Open Access Journals (Sweden)

    Boukhatem Mohammed Belkaid

    2015-06-01

    Full Text Available Satellite image Security is playing a vital role in the field of communication system and Internet. This work is interested in securing transmission of Meteosat images on the Internet, in public or local networks. To enhance the security of Meteosat transmission in network communication, a hybrid encryption algorithm based on Advanced Encryption Standard (AES and Rivest Shamir Adleman (RSA algorithms is proposed. AES algorithm is used for data transmission because of its higher efficiency in block encryption and RSA algorithm is used for the encryption of the key of the AES because of its management advantages in key cipher. Our encryption system generates a unique password every new session of encryption. Cryptanalysis and various experiments have been carried out and the results were reported in this paper, which demonstrate the feasibility and flexibility of the proposed scheme.

  7. Sodium Enrichment in Yellow Supergiants: a Perspective from the Uncertainties of Reaction Rates

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Sodium overabundance in yellow supergiants has stumped people for more than 20 years. The purpose of this paper is to explore this problem from the perspective of nuclear physics. We investigate carefully the CNO and NeNa cycles that are responsible for sodium production. We investigate some key reactions in the appropriate network. We show whether and how the sodium output can be affected by the rate uncertainties in these reactions. In this way, we evaluate if a reaction is important enough to deserve a better determination of its rate in terrestrial laboratories.

  8. Clumpy molecular structures revolving the B[e] supergiant MWC 137

    CERN Document Server

    Kraus, M; Liimets, T; Cappa, C E; Duronea, N; Gunawan, D S; Oksala, M E; Santander-Garcia, M; Arias, M L; Nickeler, D H; Maravelias, G; Fernandes, M Borges; Cure, M

    2016-01-01

    The peculiar emission-line star MWC 137 with its extended optical nebula was recently classified as B[e] supergiant. To study the spatial distribution of its circumstellar molecular gas on small and large scales, we obtained near-infrared and radio observations using SINFONI and APEX, respectively. We find that the hot CO gas is arranged in moving clumpy ring and shell structures close to the star, while a cold CO envelope is encircling the borders of the optical nebula from the south to the west.

  9. Cometary Dust in the Debris of HD 31648 and HD163296: Two "Baby" Beta pictoris Stars

    Science.gov (United States)

    Sitko, Michael L.; Grady, Carol A.; Lynch, David K.; Russell, Ray W.; Hanner, Martha S.

    1999-01-01

    The debris disks surrounding the pre-main-sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 microns. Both stars possess a silicate emission feature at 10 Am that resembles that of the star P Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxene material, plus an underlying continuum of unspecified origin. The similarity in both size and structure of the silicate band suggests that the material in these systems had a processing history similar to that in our own solar system prior to the time that the grains were incorporated into comets.

  10. Herbig AeBe stars: Multiplicity and consequences

    OpenAIRE

    Duchene, Gaspard

    2014-01-01

    By virtue of their young age and intermediate mass, Herbig AeBe stars represent a cornerstone for our understanding of the mass-dependency of both the stellar and planetary formation processes. In this contribution, I review the current state-of-the-art multiplicity surveys of Herbig AeBe stars to assess both the overall frequency of companions and the distribution of key orbital parameters (separation, mass ratio and eccentricity). In a second part, I focus on the interplay between the multi...

  11. Security of the AES with a Secret S-Box

    DEFF Research Database (Denmark)

    Tiessen, Tyge; Knudsen, Lars Ramkilde; Kölbl, Stefan;

    2015-01-01

    How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds? In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret...... key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 217/216, 238/240 and 290/264, respectively. Another...

  12. Validation and empirical correction of MODIS AOTand AE over ocean

    OpenAIRE

    N. A. J. Schutgens; Nakata, M; Nakajima, T.

    2013-01-01

    We present a validation study of Coll. 5 MODIS level 2 Aqua and Terra AOT and AE over ocean by comparison to coastal and island AERONET sites for the years 2003–2009. We show that MODIS AOT exhibits significant biases due to windspeed and cloudiness of the observed scene, while MODIS AE although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against marine AERONET data, suggesting that ...

  13. HD-DVD曙光初现——东芝HD-XA1 HD DVD播放机

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    全球首部HD DVD播放机已经推出,它就是TOSHIBA HD—XA1,这也意味蕾HD高;膏视频时代即将来到我们身边。虽然在早期,HD视频相关产品的价格不可避免地的会高高在上,但并不影响我们第一时间对这款划时代的播放机进行评测。

  14. The Transiting Exocomets of HD 172555

    Science.gov (United States)

    Grady, C. A.; Brown, Alex; Kamp, Inga; Riviere-Marichalar, Pablo; Roberge, Aki; Welsh, Barry

    2016-01-01

    While most attention has been garnered by searches for super-Jovian mass exo-planets the presence of minor bodies can be detected, at least through their dissociation products in suitably oriented systems. The principal detection technique is line-of-sight absorption spectroscopy of systems viewed close to edge-on. I review what we have learned about such bodies in beta Pictoris, and HD 172555, their link to more massive bodies in their systems, and what this tells us about the frequency and potential locations of Jovian-mass bodies in advance of their direct imaging detection.

  15. Performance and enhancement for HD videoconference environment

    OpenAIRE

    Turull Torrents, Daniel

    2008-01-01

    In this work proposed here is framed in the project of research V3 (Video, Videoconference, and Visualization) of the Foundation i2CAT, that has for final goal to design and development of a platform of video, videoconference and independent visualization of resolution in high and super though inside new generation IP networks. i2CAT Foundation uses free software for achieving its goals. UltraGrid for the transmission of HD video is used and SAGE is used for distributed visualization among mu...

  16. Dynamical Spot Evolution in HD 11753

    OpenAIRE

    Korhonen, H.; Hubrig, S.; Briquet, Maryline; González, J.F.; Savanov, I.

    2011-01-01

    Our recent studies of HD 11753, a late B-type star showing a HgMn peculiarity for the first time revealed the presence of a fast dynamical evolution of chemical spots on the surface of this chemically peculiar early-type star. These observations suggest a hitherto unknown physical process operating in stars with outer radiative envelopes. Furthermore, we have also discovered existence of magnetic fields on HgMn stars that were up to now considered non-magnetic. Here we will discuss the dyna...

  17. On the importance of the wind emission to the optical continuum of OB supergiants

    CERN Document Server

    Kraus, Michaela; Krticka, Jiri

    2008-01-01

    Thermal wind emission in the form of free-free and free-bound emission is known to show up in the infrared and radio continuum of hot and massive stars. For OB supergiants with moderate mass loss rates and a wind velocity distribution with \\beta = 0.8...1.0, no influence of the wind to the optical continuum, i.e. for \\lambda 1. For the case of a spherically symmetric, isothermal wind in local thermodynamical equilibrium (LTE) we calculate the free-free and free-bound processes and the emerging wind and total continuum spectra. We localize the generation region of the optical wind continuum and especially focus on the influence of a \\beta-type wind velocity distribution with \\beta > 1 on the formation of the wind continuum at optical wavelengths. The optical wind continuum is found to be generated within about 2 R_* which is exactly the wind region where \\beta strongly influences the density distribution. We find that for \\beta > 1, the continuum of a typical OB supergiant can indeed be contaminated with ther...

  18. Red Supergiant Stars as Cosmic Abundance Probes. III. NLTE effects in J-band Magnesium lines

    CERN Document Server

    Bergemann, Maria; Gazak, Zach; Davies, Ben; Plez, Bertrand

    2014-01-01

    Non-LTE calculations for Mg I in red supergiant stellar atmospheres are presented to investigate the importance of non-LTE for the formation of Mg I lines in the NIR J-band. Recent work using medium resolution spectroscopy of atomic lines in the J-band of individual red supergiant stars has demonstrated that technique is a very promising tool to investigate the chemical composition of the young stellar population in star forming galaxies. As in previous work, where non-LTE effects were studied for iron, titanium and silicon, substantial effects are found resulting in significantly stronger Mg I absorption lines. For the quantitative spectral analysis the non-LTE effects lead to magnesium abundances significantly smaller than in LTE with the non-LTE abundance corrections varying smoothly between -0.4 dex to -0.1 dex for effective temperatures between 3400 K to 4400 K. We discuss the physical reasons of the non-LTE effects and the consequences for extragalactic J-band abundance studies using individual red supe...

  19. The Coolest Stars in the Clouds: Unusual Red Supergiants in the Magellanic Clouds

    CERN Document Server

    Levesque, Emily M; Olsen, K A G; Plez, Bertrand

    2007-01-01

    Red supergiants (RSGs) are a He-burning phase in the evolution of moderately high mass stars (10-25 solar masses). The evolution of these stars, particularly at low metallicities, is still poorly understood. The latest-type RSGs in the Magellanic Clouds are cooler than the current evolutionary tracks allow, occupying the region to the right of the Hayashi limit where stars are no longer in hydrodynamic equilibrium. We have discovered four Cloud RSGs in this region that display remarkably similar unusual behavior. All of them show considerable variations in their V magnitudes and effective temperatures (and spectral types). Two of these stars, HV 11423 and [M2002] SMC 055188, have been observed in an M4.5 I state, considerably later and cooler than any other supergiant in the SMC. These stars suffer dramatic physical changes on timescales of months - when they are at their warmest, they are also brighter, more luminous, and show an increased amount of extinction. This variable extinction is characteristic of t...

  20. <3D> NLTE line formation in the atmospheres of red supergiants

    CERN Document Server

    Bergemann, Maria; Davies, Ben; Plez, Bertrand; Gazak, Zach; Chiavassa, Andrea

    2013-01-01

    Red supergiants with their enormous brightness at J-band are ideal probes of cosmic chemical composition. It is therefore crucial to have realistic models of radiative transfer in their atmospheres, which will permit determination of abundances accurate to 0.15 dex, the precision attainable with future telescope facilities in galaxies as distant as tens of Mpc. Here, we study the effects of non-local thermodynamic equilibrium (NLTE) on the formation of iron, titanium, and silicon lines, which dominate J-band spectra of red supergiants. It is shown that the NLTE radiative transfer models enable accurate derivation of metallicity and effective temperature in the J-band. We also discuss consequences for RSG spectrum synthesis in different spectral windows, including the heavily TiO-blanketed optical region, and atmospheric structure. We then touch upon challenges of NLTE integration with new generation of 3D hydrodynamical RSG models and present the first calculations of NLTE spectra with the mean 3D model of Be...

  1. Two Ring Nebulae around Blue Supergiants in the Large Magellanic Cloud

    CERN Document Server

    Weis, K; Duschl, W J; Bomans, D J

    1997-01-01

    Ring nebulae are often found around massive stars such as Wolf-Rayet stars, OB and Of stars and Luminous Blue Variables (LBVs). In this paper we report on two ring nebulae around blue supergiants in the Large Magellanic Cloud. The star Sk-69 279 is classified as O9f and is surrounded by a closed shell with a diameter of 4.5 pc. Our echelle observations show an expansion velocity of 14 km/s and a high [N II]6583A/H alpha ratio. This line ratio suggests nitrogen abundance enhancement consistent with those seen in ejectas from LBVs. Thus the ring nebula around Sk-69 279 is a circumstellar bubble. The star Sk-69 271, a B2 supergiant, is surrounded by an H alpha arc resembling an half shell. Echelle observations show a large expanding shell with the arc being part of the approaching surface. The expansion velocity is about 24 km/s and the [N II]6583A/H alpha is not much higher than that of the background emission. The lack of nitrogen abundance anomaly suggests that the expanding shell is an interstellar bubble wi...

  2. The Discovery of a Massive Cluster of Red Supergiants with GLIMPSE

    CERN Document Server

    Alexander, Michael J; Clemens, Dan P; Jameson, Katherine; Pinnick, April; Pavel, Michael

    2009-01-01

    We report the discovery of a previously unknown massive Galactic star cluster at l=29.22, b=-0.20. Identified visually in mid-IR images from the Spitzer GLIMPSE survey, the cluster contains at least 8 late-type supergiants, based on followup near-IR spectroscopy, and an additional 3-6 candidate supergiant embers having IR photometry consistent with a similar distance and reddening. The cluster lies at a local minimum in the 13-CO column density and 8 micron emission. We interpret this feature as a hole carved by the energetic winds of the evolving massive stars. The 13-CO hole seen in molecular maps at V_LSR ~95 km/s corresponds to near/far kinematic distances of 6.1/8.7+/-1 kpc. We calculate a mean spectrophotometric distance of 7.0^+3.7_-2.4 kpc, broadly consistent with the kinematic distances inferred. This location places it near the northern end of the Galactic bar. For the mean extinction of A_V=12.6+/-0.5 mag (A_K=1.5+/-0.1 mag), the color-magnitude diagram of probable cluster members is well fit by is...

  3. Elemental abundances of the supergiant stars {\\sigma} Cygnus and {\\eta} Leonis

    CERN Document Server

    Tanriverdi, Taner

    2015-01-01

    This study aims to analyse the elemental abundances for the late B type supergiant star $\\sigma$ Cyg and the early A-type supergiant $\\eta$ Leo using ATLAS9 (Kurucz, 1995; Sbordone et al., 2004), assuming local thermodynamic equilibrium (LTE). The spectra used in this study are obtained from Dominion Astrophysical Observatory and have high resolution and signal-to-noise ratios. The effective temperature and the surface gravity of $\\sigma$ Cyg are determined from the ionisation equilibria of Al I/II, Mg I/II, Fe I/II, Fe II/III , and by fitting to the wings of H$_\\gamma$ and H$_\\beta$ profiles as $\\textit{T}$$_{eff}$ = 10388 K and log $\\textit{g}$ = 1.80. The elemental abundances of $\\eta$ Leo} are determined using $\\textit{T}$$_{eff}$ = 9600 K and log $\\textit{g}$ = 2.00, as reported by Przybilla et al. (2006). The ionisation equilibria of C I/II, N I/II, Mg I/II, Ca I/II, Cr I/II and Fe I/II/III are also satisfied in the atmosphere of $\\eta$ Leo. The radial velocities of $\\sigma$ Cyg and $\\eta$ Leo are -7.25...

  4. GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC3

    CERN Document Server

    Origlia, L; Sanna, N; Mucciarelli, A; Dalessandro, E; Scuderi, S; Baffa, C; Biliotti, V; Carbonaro, L; Falcini, G; Giani, E; Iuzzolino, M; Massi, F; Sozzi, M; Tozzi, A; Ghedina, A; Ghinassi, F; Lodi, M; Harutyunyan, A; Pedani, M

    2015-01-01

    The Scutum complex in the inner disk of the Galaxy has a number of young star clusters dominated by red supergiants that are heavily obscured by dust extinction and observable only at infrared wavelengths. These clusters are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy. During the technical commissioning and as a first science verification of the GIANO spectrograph at the Telescopio Nazionale Galileo, we secured high-resolution (R=50,000) near-infrared spectra of five red supergiants in the young Scutum cluster RSGC3. Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to measure several tens of atomic and molecular lines that were suitable for determining chemical abundances. By means of spectral synthesis and line equivalent width measurements, we obtained abundances of Fe and iron-peak elements such as Ni, Cr, and Cu, alpha (O, Mg, Si, Ca, Ti), other light elements (C, N, F, Na, Al, and Sc), and some s-process...

  5. The Red Supergiant Progenitor of Supernova 2012aw (PTF12bvh) in Messier 95

    CERN Document Server

    Van Dyk, Schuyler D; Poznanski, Dovi; Arcavi, Iair; Gal-Yam, Avishay; Filippenko, Alexei V; Silverio, Kathryn; Stockton, Alan; Cuillandre, Jean-Charles; Marcy, Geoffrey W; Howard, Andrew W; Isaacson, Howard

    2012-01-01

    We report on the direct detection and characterization of the probable red supergiant progenitor of the intermediate-luminosity Type II-Plateau (II-P) supernova (SN) 2012aw in the nearby (10.0 Mpc) spiral galaxy Messier 95 (M95; NGC 3351). We have identified the star in both Hubble Space Telescope images of the host galaxy, obtained 17-18 yr prior to the explosion, and near-infrared ground-based images, obtained 6-12 yr prior to the SN. The luminous supergiant showed evidence for substantial circumstellar dust, manifested as excess line-of-sight extinction. The effective total-to-selective ratio of extinction to the star was R'_V \\approx 4.35, which is significantly different from that of diffuse interstellar dust (i.e., R_V=3.1), and the total extinction to the star was therefore, on average, A_V \\approx 3.1 mag. We find that the observed spectral energy distribution for the progenitor star is consistent with an effective temperature of 3600 K (spectral type M3), and that the star therefore had a bolometric ...

  6. GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC2

    CERN Document Server

    Origlia, L; Maiolino, R; Mucciarelli, A; Baffa, C; Biliotti, V; Bruno, P; Falcini, G; Gavriousev, V; Ghinassi, F; Giani, E; Gonzalez, M; Leone, F; Lodi, M; Massi, F; Montegriffo, P; Mochi, I; Pedani, M; Rossetti, E; Scuderi, S; Sozzi, M; Tozzi, A

    2013-01-01

    The inner disk of the Galaxy has a number of young star clusters dominated by red supergiants that are heavily obscured by dust extinction and observable only at infrared wavelengths. These clusters are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy. During the technical commissioning and as a first science verification of the GIANO spectrograph at the Telescopio Nazionale Galileo, we secured high-resolution (R~50,000) near-infrared spectra of three red supergiants in the young Scutum cluster RSGC2. Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to identify several tens of atomic and molecular lines suitable for chemical abundance determinations. By means of spectral synthesis and line equivalent width measurements, we obtained abundances of Fe and other iron-peak elements such as V, Cr, Ni, of alpha (O, Mg, Si, Ca and Ti) and other light elements (C, N, Na, Al, K, Sc), and of some s-process elements (Y, Sr). ...

  7. Double bow shocks around young, runaway red supergiants: application to Betelgeuse

    CERN Document Server

    Mackey, Jonathan; Neilson, Hilding R; Langer, Norbert; Meyer, Dominique M -A

    2012-01-01

    A significant fraction of massive stars are moving supersonically through the interstellar medium (ISM), either due to disruption of a binary system or ejection from their parent star cluster. The interaction of their wind with the ISM produces a bow shock. In late evolutionary stages these stars may undergo rapid transitions from red to blue and vice versa on the Hertzsprung-Russell diagram, with accompanying rapid changes to their stellar winds and bow shocks. Recent 3D simulations of the bow shock produced by the nearby runaway red supergiant (RSG) Betelgeuse, under the assumption of a constant wind, indicate that the bow shock is very young (<30000 years old), hence Betelgeuse may have only recently become a RSG. To test this possibility, we have calculated stellar evolution models for single stars which match the observed properties of Betelgeuse in the RSG phase. The resulting evolving stellar wind is incorporated into 2D hydrodynamic simulations in which we model a runaway blue supergiant (BSG) as i...

  8. Water in Emission in the ISO Spectrum of the Early M Supergiant Star mu Cephei

    CERN Document Server

    Tsuji, T

    2000-01-01

    We report a detection of water in emission in the spectrum of the M2 supergiant atar mu Cep (M2Ia) observed by the Short Wavelength Spectrometer (SWS) aboard Infrared Space Observatory (ISO) and now released as the ISO Archives. The emission first appears in the 6 micron region (nu2 fundamental) and then in the 40 micron region (pure rotation lines) despite the rather strong dust emission. The intensity ratios of the emission features are far from those of the optically thin gaseous emission. Instead, we could reproduce the major observed emission features by an optically thick water sphere of the inner radius about two stellar radii (1300Rsun), Tex = 1500K, and Ncol (H2O) = 3.0E+20/cm2. This model also accounts for the H2O absorption bands in the near infrared (1.4, 1.9, and 2.7 micron) as well. The detection of water in emission provides strong constraints on the nature of water in the early M supergiant stars, and especially its origin in the outer atmosphere is confirmed against other models such as the l...

  9. Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks

    CERN Document Server

    Hubrig, S; Schöller, M; Grady, C; Schuetz, O; Pogodin, M A; Cure, M; Hamaguchi, K; Yudin, R V

    2009-01-01

    Among the 21 Herbig Ae/Be stars studied, new detections of a magnetic field were achieved in six stars. For three Herbig Ae/Be stars, we confirm previous magnetic field detections. The largest longitudinal magnetic field, = -454+-42G, was detected in the Herbig Ae/Be star HD101412 using hydrogen lines. No field detection at a significance level of 3sigma was achieved in stars with debris disks. Our study does not indicate any correlation of the strength of the longitudinal magnetic field with disk orientation, disk geometry, or the presence of a companion. We also do not see any simple dependence on the mass-accretion rate. However, it is likely that the range of observed field values qualitatively supports the expectations from magnetospheric accretion models giving support for dipole-like field geometries. Both the magnetic field strength and the X-ray emission show hints for a decline with age in the range of ~2-14Myrs probed by our sample supporting a dynamo mechanism that decays with age. However, our s...

  10. The algorithm AE11 of learning from examples

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-yi; BI Jian-dong

    2006-01-01

    We first put forward the idea of a positive extension matrix (PEM) on paper. Then, an algorithm,AE11. was built with the aid of the PEM. Finally, we made the comparisons of our experimental results and the final result was fairly satisfying.

  11. 15 CFR 758.2 - Automated Export System (AES).

    Science.gov (United States)

    2010-01-01

    ... that agency. See 15 CFR 30.62(b) of the FTSR. (b) BIS Option 4 application process. When AES filers... Regulations (FTSR) (15 CFR Part 30) contain provisions for filing Shipper's Export Declarations (SEDs... Census Bureau for certification and approval through a Letter of Intent (see 15 CFR 30.60(b) and...

  12. Herbig Ae/Be Stars in nearby OB associations

    CERN Document Server

    Hernández, J; Hartmann, L; Briceño, C; Sicilia-Aguilar, A; Berlind, P; Hernandez, Jesus; Calvet, Nuria; Hartmann, Lee; Briceno, Cesar; Sicilia-Aguilar, Aurora; Berlind, Perry

    2004-01-01

    We have carried out a study of the early type stars in nearby OB associations spanning an age range of $\\sim$ 3 to 16 Myr, with the aim of determining the fraction of stars which belong to the Herbig Ae/Be class. We studied the B, A, and F stars in the nearby ($\\le 500$ pc) OB associations Upper Scorpius, Perseus OB2, Lacerta OB1, and Orion OB1, with membership determined from Hipparcos data. We obtained spectra for 440 Hipparcos stars in these associations, from which we determined accurate spectral types, visual extinctions, effective temperatures, luminosities and masses, using Hipparcos photometry. Using colors corrected for reddening, we find that the Herbig Ae/Be stars and the Classical Be stars (CBe) occupy clearly different regions in the JHK diagram. Thus, we use the location on the JHK diagram, as well as the presence of emission lines and of strong 12 microns flux relative to the visual to identify the Herbig Ae/Be stars in the associations. We find that the Herbig Ae/Be stars constitute a small fr...

  13. Ultra-low power S-Boxes architecture for AES

    Institute of Scientific and Technical Information of China (English)

    XING Ji-peng; ZOU Xue-cheng; GUO Xu

    2008-01-01

    It is crucial to design energy-efficient advancedcncryption standard (AES) cryptography for low power embeddedsystems powered by limited battery. Since the S-Boxes consumemuch of the total AES circuit power, an efficient approach toreducing the AES power consumption consists in reducing theS-Boxes power consumption. Among various implementationsof S-Boxes, the most energy-efficient one is the decoder-switch-encoder (DSE) architecture. In this paper, we refine the DSEarchitecture and propose one faster, more compact S-Boxesarchitecture of lower power: an improved and full-balanced DSEarchitecture. This architecture achieves low power consumptionof 68 μW at 10 MHz using 0.25 μm 1.8V UMC CMOStechnology. Compared with the original DSE S-Boxes, it furtherreduces the delay, gate count and power consumption by 8%,14% and 10% respectively. At the sane time, simulation resultsshow that the improved DSE S-Boxes has the best performanceamong various S-Boxes architectures in terms of power-areaproduct and power-delay product, and it is optimal forimplementing low power AES cryptography.

  14. Near-Earth bursty bulk flows and AE index

    Institute of Scientific and Technical Information of China (English)

    ZHANG LingQian; SHI JianKui; LIU ZhenXing; W BAUMJOHANN; MA ZhiWei; M. W. DUNLOP; C. CARR; H. REME

    2008-01-01

    With the 4-s resolution data of the magnetometer and the ion plasma analyzer on TC-1 from June to November of each year during the period of 2004-2006, we statistically analyzed the occurrence rate of both convective and field-aligned bursty flows (FABFs). A near-Earth bursty bulk flow (NEBBF) occurred during both the quiet time and substorm process. In general, the magnetic field and the plasma density began oscillating with the appearance of the NEBBF associated with a distinct increase of the AE index. The increase of AE index during the NEBBF was more than 100 nT in both quiet time and substorm process. The statistical analysis indicated that the occurrence rates of the FABFs were nearly the same in the dif-ferent stages of the AE index, but the occurrence rate of the NEBBFs was much higher in the growth stage of the AE index, indicating that the NEBBFs were di-rectly related to the growth and expansion phases of the substorm. The observa-tions suggested that the quite large number of BBFs from the mid magnetotail could enter into the near-Earth tail and play important role in triggering the sub-storm onset.

  15. BVRI Photometry of nz Gem, HD 73017, HD 77247, RT Vir and 104 Her

    Science.gov (United States)

    Adelman, Saul J.; Harrell, William L.

    We examined single channel differential BVRI photometry of the cool stars NZ Gem, HD 73017, HD 77247, RT Vir and 104 Her obtained by the first author with the Four College Automated Photoelectric Telescope with of order 100 observations taken over two or more years. Four of these stars are Small-Amplitude Red Variables (SARVs). The primary period of NZ Gem (M3 II-IIIs) is about 33.70 days. HD 77247, the shortest period barium star with spectral type K0, has a photometric period of about 82 days which is close to its binary period of 80.53 days. Its check star HD 73017, a non-variable in B, V and R, is variable in I due most likely to a previously unknown cooler companion. RT Vir (M8 III) is found to be a multiperiodic star whose observations are consistent with the 155 day primary period of Lebzelter & Hinkle (2002). 104 Her (M3 III) is also multiperiodic with a primary period of 21.48 days.

  16. The mineral clouds on HD 209458b and HD189733b

    CERN Document Server

    Helling, Ch; Dobbs-Dixon, I; Mayne, N; Amundsen, D S; Khaimova, J; Unger, A A; Manners, J; Acreman, D; Smith, C

    2016-01-01

    3D atmosphere model results are used to comparatively study the kinetic, non-equilibrium cloud formation in the atmospheres of two example planets guided by the giant gas planets HD209458b and HD189733b. Rather independently of hydrodynamic model differences, our cloud modelling suggests that both planets are covered in mineral clouds throughout the entire modelling domain. Both planets harbour chemically complex clouds that are made of mineral particles that have a height-dependent material composition and size. The remaining gas-phase element abundances strongly effects the molecular abundances of the atmosphere in the cloud forming regions. Hydrocarbon and cyanopolyyne molecules can be rather abundant in the inner, dense part of the atmospheres of HD189733b and HD209458b. No one value for metallicity and the C/O ratio can be used to describe an extrasolar planet. Our results concerning the presence and location of water in relation to the clouds explain some of the observed discrepancies between the two pl...

  17. Numerical predictions for planets in the debris discs of HD 202628 and HD 207129

    Science.gov (United States)

    Thilliez, E.; Maddison, S. T.

    2016-04-01

    Resolved debris disc images can exhibit a range of radial and azimuthal structures, including gaps and rings, which can result from planetary companions shaping the disc by their gravitational influence. Currently, there are no tools available to determine the architecture of potential companions from disc observations. Recent work by Rodigas, Malhotra & Hinz presents how one can estimate the maximum mass and minimum semimajor axis of a hidden planet empirically from the width of the disc in scattered light. In this work, we use the predictions of Rodigas et al. applied to two debris discs HD 202628 and HD 207129. We aim to test if the predicted orbits of the planets can explain the features of their debris disc, such as eccentricity and sharp inner edge. We first run dynamical simulations using the predicted planetary parameters of Rodigas et al., and then numerically search for better parameters. Using a modified N-body code including radiation forces, we perform simulations over a broad range of planet parameters and compare synthetics images from our simulations to the observations. We find that the observational features of HD 202628 can be reproduced with a planet five times smaller than expected, located 30 AU beyond the predicted value, while the best match for HD 207129 is for a planet located 5-10 AU beyond the predicted location with a smaller eccentricity. We conclude that the predictions of Rodigas et al. provide a good starting point but should be complemented by numerical simulations.

  18. CHARACTERIZING THE RIGIDLY ROTATING MAGNETOSPHERE STARS HD 345439 AND HD 23478

    Energy Technology Data Exchange (ETDEWEB)

    Wisniewski, J. P.; Lomax, J. R. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Chojnowski, S. D. [Department of Astronomy, New Mexico State University, 1780 E University Avenue, Las Cruces, NM 88003 (United States); Davenport, J. R. A. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Bartz, J.; Pepper, J. [Lehigh University, Department of Physics, 413 Deming Lewis Lab, 16 Memorial Drive, East Bethlehem, PA 18015 (United States); Whelan, D. G. [Department of Physics, Austin College, 900 N. Grand Avenue, Sherman, TX 75090 (United States); Eikenberry, S. S. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Majewski, S. R.; Skrutskie, M. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Richardson, N. D., E-mail: wisniewski@ou.edu [Département de Physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada)

    2015-10-01

    The SDSS III APOGEE survey recently identified two new σ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the Kilodegree Extremely Little Telescope, Wide Angle Search for Planets, and ASAS surveys reveals the presence of a ∼0.7701 day period in each data set, suggesting the system is among the faster known σ Ori E analogs. We also see clear evidence that the strength of Hα, H i Brackett series lines, and He i lines also vary on a ∼0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5 m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H i lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H i Br-11 line strength and line profile in multi-epoch observations of HD 23478 from the SDSS-III APOGEE instrument. The observed periodic behavior is consistent with that recently reported by Sikora and collaborators in optical spectra.

  19. Tetrabenazine as anti-chorea therapy in Huntington Disease: an open-label continuation study. Huntington Study Group/TETRA-HD Investigators

    Directory of Open Access Journals (Sweden)

    Frank Samuel

    2009-12-01

    Full Text Available Abstract Background Tetrabenazine (TBZ selectively depletes central monoamines by reversibly binding to the type-2 vesicular monoamine transporter. A previous double blind study in Huntington disease (HD demonstrated that TBZ effectively suppressed chorea, with a favorable short-term safety profile (Neurology 2006;66:366-372. The objective of this study was to assess the long-term safety and effectiveness of TBZ for chorea in HD. Methods Subjects who completed the 13-week, double blind protocol were invited to participate in this open label extension study for up to 80 weeks. Subjects were titrated to the best individual dose or a maximum of 200 mg/day. Chorea was assessed using the Total Maximal Chorea (TMC score from the Unified Huntington Disease Rating Scale. Results Of the 75 participants, 45 subjects completed 80 weeks. Three participants terminated due to adverse events (AEs including depression, delusions with associated previous suicidal behavior, and vocal tics. One subject died due to breast cancer. The other 26 subjects chose not to continue on with each ensuing extension for various reasons. When mild and unrelated AEs were excluded, the most commonly reported AEs (number of subjects were sedation/somnolence (18, depressed mood (17, anxiety (13, insomnia (10, and akathisia (9. Parkinsonism and dysphagia scores were significantly increased at week 80 compared to baseline. At week 80, chorea had significantly improved from baseline with a mean reduction in the TMC score of 4.6 (SD 5.5 units. The mean dosage at week 80 was 63.4 mg (range 12.5-175 mg. Conclusions TBZ effectively suppresses HD-related chorea for up to 80 weeks. Patients treated chronically with TBZ should be monitored for parkinsonism, dysphagia and other side effects including sleep disturbance, depression, anxiety, and akathisia. Trial Registration Clinicaltrials.gov registration number (initial study: NCT00219804

  20. Supraphysiologic levels of the AML1-ETO isoform AE9a are essential for transformation.

    Science.gov (United States)

    Link, Kevin A; Lin, Shan; Shrestha, Mahesh; Bowman, Melissa; Wunderlich, Mark; Bloomfield, Clara D; Huang, Gang; Mulloy, James C

    2016-08-01

    Chromosomal translocation 8;21 is found in 40% of the FAB M2 subtype of acute myeloid leukemia (AML). The resultant in-frame fusion protein AML1-ETO (AE) acts as an initiating oncogene for leukemia development. AE immortalizes human CD34(+) cord blood cells in long-term culture. We assessed the transforming properties of the alternatively spliced AE isoform AE9a (or alternative splicing at exon 9), which is fully transforming in a murine retroviral model, in human cord blood cells. Full activity was realized only upon increased fusion protein expression. This effect was recapitulated in the AE9a murine AML model. Cotransduction of AE and AE9a resulted in a strong selective pressure for AE-expressing cells. In the context of AE, AE9a did not show selection for increased expression, affirming observations of human t(8;21) patient samples where full-length AE is the dominant protein detected. Mechanistically, AE9a showed defective transcriptional regulation of AE target genes that was partially corrected at high expression. Together, these results bring an additional perspective to our understanding of AE function and highlight the contribution of oncogene expression level in t(8;21) experimental models. PMID:27457952

  1. The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing

    Science.gov (United States)

    Wisniewski, John P.; Clampin, Mark; Grady, Carol A.; Ardila, David R.; Ford, Holland C.; Golimowski, David A.; Illingworth, Garth D.; Krist, John E.

    2008-01-01

    We present the first multi-color view of the scattered light disk of the Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble Space Telescope Advanced Camera for Surveys (ACS). Radial profile fits of the surface brightness along the disk's semi-major axis indicates that the disk is not continuously flared, and extends to approx.540 AU. The disk's color (V-I)=1.1 at a radial distance of 3.5" is redder than the observed stellar color (V-I)=0.15. This red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition, both of which would be consistent with the observed non-flared geometry of the outer disk. We also identify a single ansa morphological structure in our F435W ACS data, which is absent from earlier epoch F606W and F814W ACS data, but corresponds to one of the two ansa observed in archival HST STIS coronagraphic data. Following transformation to similar band-passes, we find that the scattered light disk of HD 163296 is 1 mag arcsec(sup -2) fainter at 3.5" in the STIS data than in the ACS data. Moreover, variations are seen in (i) the visibility of the ansa(e) structures, in (ii) the relative surface brightness of the ansa(e) structures, and in (iii) the (known) intrinsic polarization of the system. These results indicate that the scattered light from the HD 163296 disk is variable. We speculate that the inner disk wall, which Sitko et al. suggests has a variable scale height as diagnosed by near-IR SED variability, induces variable self-shadowing of the outer disk. We further speculate that the observed surface brightness variability of the ansa(e) structures may indicate that the inner disk wall is azimuthally asymmetric. Subject headings: circumstellar matter - stars: individual (HD 163296) - planetary systems: formation - planetary systems: protoplanetary disks

  2. Enhanced ATM Security using Biometric Authentication and Wavelet Based AES

    Directory of Open Access Journals (Sweden)

    Sreedharan Ajish

    2016-01-01

    Full Text Available The traditional ATM terminal customer recognition systems rely only on bank cards, passwords and such identity verification methods are not perfect and functions are too single. Biometrics-based authentication offers several advantages over other authentication methods, there has been a significant surge in the use of biometrics for user authentication in recent years. This paper presents a highly secured ATM banking system using biometric authentication and wavelet based Advanced Encryption Standard (AES algorithm. Two levels of security are provided in this proposed design. Firstly we consider the security level at the client side by providing biometric authentication scheme along with a password of 4-digit long. Biometric authentication is achieved by considering the fingerprint image of the client. Secondly we ensure a secured communication link between the client machine to the bank server using an optimized energy efficient and wavelet based AES processor. The fingerprint image is the data for encryption process and 4-digit long password is the symmetric key for the encryption process. The performance of ATM machine depends on ultra-high-speed encryption, very low power consumption, and algorithmic integrity. To get a low power consuming and ultra-high speed encryption at the ATM machine, an optimized and wavelet based AES algorithm is proposed. In this system biometric and cryptography techniques are used together for personal identity authentication to improve the security level. The design of the wavelet based AES processor is simulated and the design of the energy efficient AES processor is simulated in Quartus-II software. Simulation results ensure its proper functionality. A comparison among other research works proves its superiority.

  3. NICMOS Spectroscopy of HD 189733b

    Science.gov (United States)

    Swain, Mark R.; Deroo, Pieter; Vasisht, Gautam

    2010-01-01

    Spectral features corresponding to methane and water opacity were reported based on transmission spectroscopy of HD 189733b with Hubble/NICMOS. Recently, these data, and a similar data set for XO-1b, have been reexamined in Gibson et al. 2010, who claim they cannot reliably reproduce prior results. We examine the methods used by the Gibson team and identify two specific issues that could act to increase the formal uncertainties and to create instability in the minimization process. This would also be consistent with the GPA10 finding that they could not identify a way to select among the several instrument models they constructed. In the case of XO-1b, the Gibson team significantly changed the way in which the instrument model is defined (both with respect to the three approaches they used for HD 189733b, and the approach used by previous authors); this change, which omits the effect of the spectrum position on the detector, makes direct intercomparison of results difficult. In the experience of our group, the position of the spectrum on the detector is an important element of the instrument model because of the significant residual structure in the NICMOS spectral flat field. The approach of changing instrument models significantly complicates understanding the data reduction process and interpreting the results. Our team favors establishing a consistent method of handling NICMOS instrument systematic errors and applying it uniformly to data sets.

  4. The evolved pulsating CEMP star HD112869

    CERN Document Server

    Začs, L; Grankina, A; Deveikis, V; Kaminskyi, B; Pavlenko, Y; Musaev, F

    2015-01-01

    Radial velocity measurements, $BVR_C$ photometry, and high-resolution spectroscopy in the wavelength region from blue to near infrared are employed in order to clarify the evolutionary status of the carbon-enhanced metal-poor star HD112869 with unique ratio of carbon isotopes in the atmosphere. An LTE abundance analysis was carried out using the method of spectral synthesis and new self consistent 1D atmospheric models. The radial velocity monitoring confirmed semiregular variations with a peak-to-peak amplitude of about 10 km $s^{-1}$ and a dominating period of about 115 days. The light, color and radial velocity variations are typical of the evolved pulsating stars. The atmosphere of HD112869 appears to be less metal-poor than reported before, [Fe/H] = -2.3 $\\pm$0.2 dex. Carbon to oxygen and carbon isotope ratios are found to be extremely high, C/O $\\simeq$ 12.6 and $^{12}C/^{13}C \\gtrsim$ 1500, respectively. The s-process elements yttrium and barium are not enhanced, but neodymium appears to be overabundan...

  5. Hubble Space Telescope Observations of the HD 202628 Debris Disk

    Science.gov (United States)

    Krist, John E.; Stapelfeldt, Karl R.; Bryden, Geoffrey; Plavchan, Peter

    2012-01-01

    A ring-shaped debris disk around the G2V star HD 202628 (d = 24.4 pc) was imaged in scattered light at visible wavelengths using the coronagraphic mode of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The ring is inclined by approx.64deg from face-on, based on the apparent major/minor axis ratio, with the major axis aligned along PA = 130deg. It has inner and outer radii (> 50% maximum surface brightness) of 139 AU and 193 AU in the northwest ansae and 161 AU and 223 AU in the southeast ((Delta)r/r approx. = 0.4). The maximum visible radial extent is approx. 254 AU. With a mean surface brightnesses of V approx. = 24 mag arcsec.(sup -2), this is the faintest debris disk observed to date in reflected light. The center of the ring appears offset from the star by approx.28 AU (deprojected). An ellipse fit to the inner edge has an eccentricity of 0.18 and a = 158 AU. This offset, along with the relatively sharp inner edge of the ring, suggests the influence of a planetary-mass companion. There is a strong similarity with the debris ring around Fomalhaut, though HD 202628 is a more mature star with an estimated age of about 2 Gyr. We also provide surface brightness limits for nine other stars in our study with strong Spitzer excesses around which no debris disks were detected in scattered light (HD 377, HD 7590, HD 38858, HD 45184, HD 73350, HD 135599, HD 145229, HD 187897, and HD 201219).

  6. SiO and H2O Maser Observations of Red Supergiants in Star Clusters Embedded in the Galactic Disk

    CERN Document Server

    Deguchi, S; Zhang, Y; Chong, S S N; Koike, K; Kwok, S

    2010-01-01

    We present the result of radio observations of red supergiants in the star cluster, Stephenson's #2, and candidates for red supergiants in the star clusters, Mercer et al. (2005)'s #4, #8, and #13, in the SiO and H$_2$O maser lines.The Stephenson's #2 cluster and nearby aggregation at the South-West contain more than 15 red supergiants. We detected one at the center of Stephenson's #2 and three in the south-west aggregation in the SiO maser line, and three of these 4 were also detected in the H2O maser line. The average radial velocity of the 4 detected objects is 96 km s^{-1}, giving a kinematic distance of 5.5 kpc, which locates this cluster near the base of the Scutum-Crux spiral arm. We also detected 6 SiO emitting objects associated with the other star clusters. In addition, mapping observations in the CO J=1--0 line toward these clusters revealed that an appreciable amount of molecular gas still remains around Stephenson's #2 cluster in contrast to the prototypical red-supergiant cluster, Bica et al.'s ...

  7. IUE observations of the Henize-Carlson sample of peculiar emission line supergiants: The galactic analogs of the Magellanic Zoo

    Science.gov (United States)

    Shore, Steven N.; Brown, Douglas N.; Sanduleak, N.

    1986-01-01

    Some 15 stars from the Carlson-Henize survey of southern peculiar emission line stars were studied. From both the optical and UV spectra, they appear to be galactic counterparts of the most extreme early-type emission line supergiants of the Magellanic Clouds.

  8. The nature of B supergiants: clues from a steep drop in rotation rates at 22 000 K

    NARCIS (Netherlands)

    Vink, J.S.; Brott, I.; Gräfener, G.; Langer, N.; de Koter, A.; Lennon, D.J.

    2010-01-01

    The location of B supergiants in the Hertzsprung-Russell diagram (HRD) represents a long-standing problem in massive star evolution. Here we propose their nature may be revealed utilising their rotational properties, and we highlight a steep drop in massive star rotation rates at an effective temper

  9. The AES/EBU Digital Audio Transmission Standard%AES/EBU数字音频传输标准

    Institute of Scientific and Technical Information of China (English)

    侯书婷; 杨宇; 徐品

    2014-01-01

    In order to ensure that all kinds of digital audio equipment in the studio to be connected to each other and transmitting data securely,the AES/ EBU ( audio engineering association/European broadcast-ing union) formulated the AES/ EBU digital audio interface standard and revised it in 1992. The standard has become a popular professional digital audio standard. This paper mainly introduces the standard in de-tail.%为了保证演播室中各种数字音频设备之间能够相互连接并且安全的传输数据,AES/EBU(声频工程协会/欧洲广播联盟)制定了AES/EBU数字音频接口标准并于1992对它进行重新修订。该标准现已成为专业数字音频较为流行的标准。本文主要对该标准进行详细的介绍。

  10. HD DVD全国首家深度报道TOSHIBA HD-A1HD DVD播放机

    Institute of Scientific and Technical Information of China (English)

    Firewan

    2006-01-01

    @@ HD DVD和蓝光为争夺谁是下一代的DVD标准已经纠缠了四年,而作为双方的正式产品也终于在今年上市.就在索尼发布搭载了蓝光的新一代游戏机的前夕,我花费近5000多元托朋友从美国帮我买的HD DVD播放机--东芝HD-A1也到家了.

  11. Real-time control of electronic motion: Application to HD+

    DEFF Research Database (Denmark)

    Grønager, Michael; Henriksen, Niels Engholm

    1998-01-01

    We show that a nonstationary electron can be created in HD+ corresponding to partial electron transfer between H+ and D+.......We show that a nonstationary electron can be created in HD+ corresponding to partial electron transfer between H+ and D+....

  12. Distillation of hydrogen isotopes for polarized HD target

    CERN Document Server

    Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouill', G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

    2011-01-01

    We have developed a cryogenic distillation system to purify Hydrogen-Deuteride (HD) gas for a polarized HD target in LEPS experiments at SPring-8. A small amount of ortho-H$_2$ ($\\sim$0.01%) in the HD gas plays an important role in efficiently polarizing the HD target. Since there are 1$\\sim$5% impurities of H$_2$ and D$_2$ in commercially available HD gases, it is inevitable that the HD gas is purified up to $\\sim$99.99%. The distillation system has a cryogenic pot (17$\\sim$21 K) containing many small stainless steel cells called Heli-pack. Commercial HD gas with an amount of 5.2 mol is fed into the pot. We carried out three distillation runs by changing temperatures (17.5 K and 20.5 K) and gas extraction speeds (1.3 ml/min and 5.2 ml/min). The extracted gas was analyzed by using a gas analyzer system combining a quadrupole mass spectrometer with a gas chromatograph. The HD gas of 1 mol with a purity better than 99.99% has been successfully obtained. The effective NTS (Number of Theoretical Stages), which is...

  13. The mass-loss rates of red supergiants at low metallicity: Detection of rotational CO emission from two red supergiants in the Large Magellanic Cloud

    CERN Document Server

    Matsuura, Mikako; Swinyard, Bruce; Yates, Jeremy; Royer, P; Barlow, M J; Boyer, Martha; Decin, L; Khouri, Theo; Meixner, Margaret; van Loon, Jacco Th; Woods, Paul M

    2016-01-01

    Using the PACS and SPIRE spectrometers on-board the Herschel Space Observatory, we obtained spectra of two red supergiants (RSGs) in the Large Magellanic Cloud (LMC). Multiple rotational CO emission lines (J=6-5 to 15-14) and 15 H2O lines were detected from IRAS 05280-6910, and one CO line was detected from WOH G64. This is the first time CO rotational lines have been detected from evolved stars in the LMC. Their CO line intensities are as strong as those of the Galactic RSG, VY CMa. Modelling the CO lines and the spectral energy distribution results in an estimated mass-loss rate for IRAS 05280-6910 of 3x10^-4 Msun per yr. The model assumes a gas-to-dust ratio and a CO-to-H2 abundance ratio is estimated from the Galactic values scaled by the LMC metallicity ([Fe/H]~-0.3), i.e., that the CO-to-dust ratio is constant for Galactic and LMC metallicities within the uncertainties of the model. The key factor determining the CO line intensities and the mass-loss rate found to be the stellar luminosity.

  14. The mass-loss rates of red supergiants at low metallicity: Detection of rotational CO emission from two red supergiants in the Large Magellanic Cloud

    Science.gov (United States)

    Matsuura, Mikako; Sargent, B.; Swinyard, Bruce; Yates, Jeremy; Royer, P.; Barlow, M. J.; Boyer, Martha; Decin, L.; Khouri, Theo; Meixner, Margaret; van Loon, Jacco Th.; Woods, Paul M.

    2016-08-01

    Using the PACS and SPIRE spectrometers on-board the Herschel Space Observatory, we obtained spectra of two red supergiants (RSGs) in the Large Magellanic Cloud (LMC). Multiple rotational CO emission lines (J=6-5 to 15-14) and 15 H2O lines were detected from IRAS 05280-6910, and one CO line was detected from WOH G64. This is the first time CO rotational lines have been detected from evolved stars in the LMC. Their CO line intensities are as strong as those of the Galactic RSG, VY CMa. Modelling the CO lines and the spectral energy distribution results in an estimated mass-loss rate for IRAS 05280-6910 of 3 × 10-4 M⊙ yr-1. The model assumes a gas-to-dust ratio and a CO-to-H2 abundance ratio is estimated from the Galactic values scaled by the LMC metallicity ([Fe/H]˜-0.3), i.e., that the CO-to-dust ratio is constant for Galactic and LMC metallicities within the uncertainties of the model. The key factor determining the CO line intensities and the mass-loss rate found to be the stellar luminosity.

  15. Differential inhibition of AE1 and AE2 anion exchangers by oxonol dyes and by novel polyaminosterol analogs of the shark antibiotic squalamine.

    Science.gov (United States)

    Alper, S L; Chernova, M N; Williams, J; Zasloff, M; Law, F Y; Knauf, P A

    1998-01-01

    Oxonol and polyaminosterol drugs were examined as inhibitors of recombinant mouse AE1 and AE2 anion exchangers expressed in Xenopus laevis oocytes and were compared as inhibitors of AE1-mediated anion flux in red cells and in HL-60 cells that express AE2. The oxonols WW-781, diBA(5)C4, and diBA(3)C4 inhibited HL-60 cell Cl-/Cl- exchange with IC50 values from 1 to 7 microM, 100-1000 times less potent than their IC50 values for red cell Cl-/anion exchange. In Xenopus oocytes, diBA(5)C4 inhibited AE1-mediated Cl- efflux several hundred times more potently than that mediated by AE2. Several novel squalamine-related polyaminosterols were also evaluated as anion exchange inhibitors. In contrast to diBA(5)C4, polyaminosterol 1361 inhibited oocyte-expressed AE2 8-fold more potently than AE1 (IC50 0.6 versus 5.2 microM). The 3-fold less potent desulfo-analog, 1360, showed similar preference for AE2. It was found that 1361 also partially inhibited Cl- efflux from red cells, whereas neither polyaminosterol inhibited Cl efflux from HL60 cells. Thus, the oxonol diBA(5)C4 is >100-fold more potent as an inhibitor of AE1 than of AE2, whereas the polyaminosterols 1360 and 1361 are 8-fold more potent as inhibitors of AE2 than of AE1. Assay conditions and cell type influenced IC50 values for both classes of compounds. PMID:10353714

  16. HD gas analysis with Gas Chromatography and Quadrupole Mass Spectrometer

    CERN Document Server

    Ohta, T; Didelez, J -P; Fujiwara, M; Fukuda, K; Kohri, H; Kunimatsu, T; Morisaki, C; Ono, S; Rouille, G; Tanaka, M; Ueda, K; Uraki, M; Utsuro, M; Wang, S Y; Yosoi, M

    2011-01-01

    A gas analyzer system has been developed to analyze Hydrogen-Deuteride (HD) gas for producing frozen-spin polarized HD targets, which are used for hadron photoproduction experiments at SPring-8. Small amounts of ortho-H$_{2}$ and para-D$_{2}$ gas mixtures ($\\sim$0.01%) in the purified HD gas are a key to realize a frozen-spin polarized target. In order to obtain reliable concentrations of these gas mixtures in the HD gas, we produced a new gas analyzer system combining two independent measurements with the gas chromatography and the QMS. The para-H$_{2}$, ortho-H$_{2}$, HD, and D$_{2}$ are separated using the retention time of the gas chromatography and the mass/charge. It is found that the new gas analyzer system can measure small concentrations of $\\sim$0.01% for the otho-H$_2$ and D$_2$ with good S/N ratios.

  17. Two Methods of AES Implementation Based on CPLD/FPGA

    Institute of Scientific and Technical Information of China (English)

    刘常澍; 彭艮鹏; 王晓卓

    2004-01-01

    This paper describes two single-chip--complex programmable logic devices/field programmable gate arrays(CPLD/FPGA)--implementations of the new advanced encryption standard (AES) algorithm based on the basic iteration architecture (design [A]) and the hybrid pipelining architecture (design [B]). Design [A] is an encryption-and-decryption implementation based on the basic iteration architecture. This design not only supports 128-bit, 192-bit, 256-bit keys, but saves hardware resources because of the iteration architecture and sharing technology. Design [B] is a method of the 2×2 hybrid pipelining architecture. Based on the AES interleaved mode of operation, the design successfully accomplishes the algorithm, which operates in the feedback mode (cipher block chaining). It not only guarantees security of encryption/decryption, but obtains high data throughput of 1.05 Gb/s. The two designs have been realized on Aitera's EP20k300EBC652-1 devices.

  18. Magnetic fields of Herbig Ae/Be stars

    Directory of Open Access Journals (Sweden)

    Hubrig S.

    2014-01-01

    Full Text Available We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. The magnetic field geometries of these stars, investigated with spectropolarimetric time series, can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields have recently been observed with X-shooter in the visible and the near-IR, as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of the accretion flow and the accretion disk gas emission.

  19. The research of DPA attacks against AES implementations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This article examines vulnerabilities to power analysis attacks between software and hardware implementations of cryptographic algorithms. Representative platforms including an Atmel 89S8252 8-bit processor and a 0.25 μm 1.8 v standard cell circuit are proposed to implement the advance encryption standard (AES). A simulation-based experimental environment is built to acquire power data, and single-bit differential power analysis (DPA), and multi-bit DPA and correlation power analysis (CPA) attacks are conducted on two implementations respectively. The experimental results show that the hardware implementation has less data-dependent power leakages to resist power attacks. Furthermore, an improved DPA approach is proposed. It adopts hamming distance of intermediate results as power model and arranges plaintext inputs to differentiate power traces to the maximal probability. Compared with the original power attacks, our improved DPA performs a successful attack on AES hardware implementations with acceptable power measurements and fewer computations.

  20. Accelerating Solution Proposal of AES Using a Graphic Processor

    Directory of Open Access Journals (Sweden)

    STRATULAT, M.

    2011-11-01

    Full Text Available The main goal of this work is to analyze the possibility of using a graphic processing unit in non graphical calculations. Graphic Processing Units are being used nowadays not only for game engines and movie encoding/decoding, but also for a vast area of applications, like Cryptography. We used the graphic processing unit as a cryptographic coprocessor in order accelerate AES algorithm. Our implementation of AES is on a GPU using CUDA architecture. The performances obtained show that the CUDA implementation can offer speedups of 11.95Gbps. The tests are conducted in two directions: running the tests on small data sizes that are located in memory and large data that are stored in files on hard drives.

  1. HD2C interacts with HDA6 and is involved in ABA and salt stress response in Arabidopsis

    OpenAIRE

    Luo, Ming; Wang, Yu-Yuan; Liu, Xuncheng; Yang, Songguang; Lu, Qing; Cui, Yuhai; Wu, Keqiang

    2012-01-01

    HD2 proteins are plant specific histone deacetylases. Four HD2 proteins, HD2A, HD2B, HD2C, and HD2D, have been identified in Arabidopsis. It was found that the expression of HD2A, HD2B, HD2C, and HD2D was repressed by ABA and NaCl. To investigate the function of HD2 proteins further, two HD2C T-DNA insertion lines of Arabidopsis, hd2c-1 and hd2c-3 were identified. Compared with wild-type plants, hd2c-1 and hd2c-3 plants displayed increased sensitivity to ABA and NaCl during germination and de...

  2. A Comparison of Problem Behavior Profiles in Turkish Children with AD/HD and Non-AD/HD Children

    Science.gov (United States)

    Ozdemir, Selda

    2010-01-01

    Introduction: There is an increasing number of studies describing the symptoms of ADHD among school-age children in western cultures. Yet, studies on children with ADHD living in non-western cultures are limited. Thus, the purpose of this study was to compare problem behavior profiles of Turkish children with AD/HD and non-AD/HD children. Method:…

  3. Resolving Close Encounters: Stability in the HD 5319 and HD 7924 Planetary Systems

    CERN Document Server

    Kane, Stephen R

    2016-01-01

    Radial velocity searches for exoplanets have detected many multi-planet systems around nearby bright stars. An advantage of this technique is that it generally samples the orbit outside of inferior/superior conjunction, potentially allowing the Keplerian elements of eccentricity and argument of periastron to be well characterized. The orbital architectures for some of these systems show signs of close planetary encounters that may render the systems unstable as described. We provide an in-depth analysis of two such systems: HD 5319 and HD 7924, for which the scenario of coplanar orbits results in rapid destabilization of the systems. The poorly constrained periastron arguments of the outer planets in these systems further emphasizes the need for detailed investigations. An exhaustive scan of parameters space via dynamical simulations reveals specific mutual inclinations between the two outer planets in each system that allow for stable configurations over long timescales. We compare these configurations with ...

  4. 众中之选八达HD-22SE CD 播放机

    Institute of Scientific and Technical Information of China (English)

    小友

    2008-01-01

    八达旗下编号为HD-22的CD播放机有三款,即HD-22、HD-22(摩机版)、HD-22SE。HD-22可视为基准版;HD-22(摩机版)则是针对某一特定消费群体的机种;HD-22SE可视为这个HD-22家族的特别版,

  5. HD 93129A AT DIFFERENT RADIO SCALES

    Directory of Open Access Journals (Sweden)

    P. Benaglia

    2010-01-01

    Full Text Available Observaciones recientes hacia la estrella HD 93129A (O2 If* han revelado emisión no-t ermica en radioondas; además, datos del FGS-HST mostraron que tiene una compañera de tipo O temprana, a 140 UA si la distancia estelar es de 2.5 kpc. Ambos resultados son consistentes con la presencia de una región de colisión de vientos entre las dos componentes. En esta región pueden acelerarse los electrones relativistas involucrados en la emisión sincrotrón. Con el objetivo de resolver la fuente no-térmica hemos llevado a cabo observaciones VLBI con el LBA australiano a 2.37 GHz. Presentamos aquí algunos resultados preliminares.

  6. Ultraviolet spectral synthesis of HD 72660

    Science.gov (United States)

    Golriz, S. S.; Landstreet, J. D.

    2016-03-01

    The study of chemical abundances in stellar atmosphere provides a useful tool to investigate the formation and evolution history of stars. The optical wavelength range has been used almost exclusively in the past to determine the elemental abundance in A-type stars. We use high-resolution, high signal-to-noise ultraviolet spectra obtained from the STIS/NUV-MAMA instrument on board Hubble Space Telescope. The spectra available cover the wavelength ranges 1630 Å-1901 Å and 2130 Å-2887 Å. The main challenge to carrying out abundance analysis in the ultraviolet is the extreme level of line blending. Abundance analysis using single isolated spectral lines is almost completely impossible; it is necessary to model spectral windows using spectrum synthesis with fairly complete line-lists. We have used the LTE spectrum synthesis code ZEEMAN to model the UV spectrum of HD 72660, adjusting abundances for a best match for elements with 6 ≤ Z≤ 82 for which lines are present in the Vinna Atomic Line Database line-list. Abundances or upper limits are derived for 32 elements. We find that except a few, our derived abundances are slightly higher than solar values. We estimate upper limits for abundances of eleven elements and abundance values of 12 elements which have not been detected in the optical. The high abundances that we find for some heavy elements may point to radiative levitation. The presence of lanthanides plus our results, suggest the reclassification of HD 72660 as a transition object between an HgMn star and an Am star.

  7. A New Distance to M33 Using Blue Supergiants and the FGLR Method

    CERN Document Server

    U, Vivian; Kudritzki, Rolf-Peter; Jacobs, Bradley A; Bresolin, Fabio; Przybilla, Norbert

    2009-01-01

    The quantitative spectral analysis of medium resolution optical spectra of A and B supergiants obtained with DEIMOS and ESI at the Keck Telescopes is used to determine a distance modulus of 24.93 +/- 0.11 mag for the Triangulum Galaxy M33. The analysis yields stellar effective temperatures, gravities, interstellar reddening, and extinction, the combination of which provides a distance estimate via the Flux-weighted Gravity--Luminosity Relationship (FGLR). This result is based on an FGLR calibration that is continually being polished. An average reddening of ~ 0.08 mag is found, with a large variation ranging from 0.01 to 0.16 mag however, demonstrating the importance of accurate individual reddening measurements for stellar distance indicators in galaxies with evident signatures of interstellar absorption. The large distance modulus found is in good agreement with recent work on eclipsing binaries, planetary nebulae, long period variables, RR Lyrae stars, and also with HST observations of Cepheids, if reason...

  8. IUE observations of HR 6902 - Effect of luminosity on supergiant chromospheres

    Science.gov (United States)

    Ahmad, Imad A.

    1990-01-01

    IUE observations of the most recently discovered Zeta Aurigae system, HR 6902, are reported to reveal profound differences in the spectrum of the chromosphere of the cool primary from those of all other Zeta Aurigae systems. Unlike its sister systems, HR 6902 shows evidence of neither strong wind nor an extended chromosphere for the cool primary. Instead, the spectrum is like that of a single blue dwarf. The most likely reason for this contrast to all other Zeta Aur systems observed with IUE is the lower luminosity of the HR 6902 primary: a type-II 'bright giant' as opposed to the type I (or Ib-II in the case of 22 Vul) 'supergiants' in the other Zeta Aur systems.

  9. Spectroscopic studies of yellow supergiants in the open cluster NGC 129

    Science.gov (United States)

    Usenko, I. A.

    2015-09-01

    Spectroscopic studies of three yellow supergiants in the open cluster NGC 129, the classical Cepheid DL Cas, SAO 21450, and SAO 21482, have been performed on the basis of high-resolution spectra. For the two nonvariable cluster supergiants, the atmospheric parameters and chemical composition have been determined for the first time. SAO 21450 ( T eff = 6541 ± 16 K, log g = 2.00, V t = 4.20 km s-1) has nearly solar abundances of the key elements in the evolution of yellow supergiants (CNO, Na, Mg, and Al), while SAO 21482 ( T eff = 4506 ± 50 K, log g = 1.10, V t = 9.90 km s-1) exhibits an overabundance of carbon ([C/H] = +0.34 dex) and aluminum and nearly solar N, O, Na, and Mg abundances. The abundances of the key elements in the Cepheid DL Cas are typical for an object that has passed the first dredge-up: a C underabundance, N and Na overabundances, and nearly solar O, Mg, and Al abundances. In all objects, the abundances of iron [Fe/H] = -0.01 dex, α-elements, Fe-peak elements, and r- and s-process elements are virtually identical and nearly solar. The radial velocities of SAO 21482 measured from metal absorption lines have confirmed its membership in NGC 129. The knifelike shape of the H α and H β line profiles in SAO 21482 and the asymmetry of the Mg Ib 5183.618 Å line in SAO 21482 and DL Cas as well as the absorption lines of neutral atoms and ions of metals in the Cepheid suggest the existence of extended gaseous envelopes around them. The positions of the objects on the T eff- L diagram among the tracks of evolutionary masses for the objects show the following: (1) the primary component of SAO 21450 has a mass of 6.6 M ⊙ and approaches the blue edge of the Cepheid instability strip (CIS) for the first time, while its companion of possible spectral type B5 V has a mass of 4.8 M ⊙; (2) DL Cas is on the path of its CIS with a mass of 5.8 M ⊙ and has lost ~1.5 M ⊙ after the first dredge-up; (3) SAO 21482 with a mass of no more than 7.3 M ⊙ has

  10. The Swift Supergiant Fast X-ray Transients Project: a review, new results, and future perspectives

    CERN Document Server

    Romano, P; Ducci, L; Esposito, P; Vercellone, S; Bocchino, F; Burrows, D N; Kennea, J A; Krimm, H A; Gehrels, N; Farinelli, R; Ceccobello, C

    2013-01-01

    We present a review of the Supergiant Fast X-ray Transients (SFXT) Project, a systematic investigation of the properties of SFXTs with a strategy that combines Swift monitoring programs with outburst follow-up observations. This strategy has quickly tripled the available sets of broad-band data of SFXT outbursts, and gathered a wealth of out-of-outburst data, which have led us to a broad-band spectral characterization, an assessment of the fraction of the time these sources spend in each phase, and their duty cycle of inactivity. We present some new observational results obtained through our outburst follow-ups, as fitting examples of the exceptional capabilities of Swift in catching bright flares and monitor them panchromatically.

  11. The Swift Supergiant Fast X-Ray Transients Project:. [A Review, New Results and Future Perspectives

    Science.gov (United States)

    Romano, P.; Mangano, V.; Ducci, L.; Esposito, P.; Vercellone, S.; Bocchino, F.; Burrows, D. N.; Kennea, J. A.; Krimm, H. A.; Gehrels, N.; Farinelli, R.; Ceccobello, C.

    2013-01-01

    We present a review of the Supergiant Fast X-ray Transients (SFXT) Project, a systematic investigation of the properties of SFXTs with a strategy that combines Swift monitoring programs with outburst follow-up observations. This strategy has quickly tripled the available sets of broad-band data of SFXT outbursts, and gathered a wealth of out-of-outburst data, which have led us to a broad-band spectral characterization, an assessment of the fraction of the time these sources spend in each phase, and their duty cycle of inactivity. We present some new observational results obtained through our outburst follow-ups, as fitting examples of the exceptional capabilities of Swift in catching bright flares and monitor them panchromatically.

  12. Two supergiants in the Large Magellanic Cloud with thick dust shells

    Science.gov (United States)

    Elias, J. H.; Frogel, J. A.; Schwering, P. B. W.

    1986-01-01

    Ground-based observations from 0.6 to 20 microns have identified two luminous, evolved stars surrounded by thick dust shells among the Magellanic Cloud sources detected by the Infrared Astronomical Satellite. Their energy distributions resemble those of typical Galactic OH/IR stars, but they have bolometric magnitudes brighter than -9 and the small-amplitude variability of supergiants. One star, IRAS 04553 - 6825, has a special type of M7.5 and a dust shell which absorbs and reradiates roughly 75 percent of the star's luminosity; its radial velocity confirms its LMC membership. The second star, IRAS 05346 - 6949, has an even thicker dust shell, and the central star is not observable.

  13. The Ionized Nebula surrounding the Red Supergiant W26 in Westerlund 1

    CERN Document Server

    Wright, Nicholas J; Drew, Janet E; Barentsen, Geert; Barlow, Michael J; Walsh, Jeremy R; Zijlstra, Albert; Drake, Jeremy J; Eisloffel, Jochen; Farnhill, Hywel J

    2013-01-01

    We present H\\alpha images of an ionized nebula surrounding the M2-5Ia red supergiant (RSG) W26 in the massive star cluster Westerlund 1. The nebula consists of a circumstellar shell or ring ~0.1pc in diameter and a triangular nebula ~0.2pc from the star that in high-resolution Hubble Space Telescope images shows a complex filamentary structure. The excitation mechanism of both regions is unclear since RSGs are too cool to produce ionizing photons and we consider various possibilities. The presence of the nebula, high stellar luminosity and spectral variability suggest that W26 is a highly evolved RSG experiencing extreme levels of mass-loss. As the only known example of an ionized nebula surrounding a RSG W26 deserves further attention to improve our understanding of the final evolutionary stages of massive stars.

  14. Efficient Hardware Design and Implementation of AES Cryptosystem

    Directory of Open Access Journals (Sweden)

    Pravin B. Ghewari

    2010-03-01

    Full Text Available We propose an efficient hardware architecture design & implementation of Advanced Encryption Standard (AES-Rijndael cryptosystem. The AES algorithm defined by the National Institute of Standard and Technology(NIST of United States has been widely accepted. The cryptographic algorithms can be implemented with software or built with pure hardware. However Field Programmable Gate Arrays (FPGA implementation offers quicker solution and can be easily upgraded to incorporate any protocol changes. This contribution investigates the AES encryption and decryption cryptosystem with regard to FPGA and Very High Speed Integrated Circuit Hardware Description language (VHDL. Optimized and Synthesizable VHDL code is developed for theimplementation of both 128- bit data encryption and decryption process. Xilinx ISE 8.1 software is used for simulation. Each program is tested with some of the sample vectors provided by NIST and output results are perfect with minimal delay. The throughput reaches the value of 352 Mbit/sec for both encryption and decryption process with Device XCV600 of Xilinx Virtex Family.

  15. Effective Comparison and Evaluation of DES and Rijndael Algorithm (AES

    Directory of Open Access Journals (Sweden)

    Prof.N..Penchalaiah,

    2010-08-01

    Full Text Available This paper discusses the effective coding of Rijndael algorithm, Advanced Encryption Standard (AES in Hardware Description Language, Verilog. In this work we analyze the structure and design of new AES, following three criteria: a resistance against all known attacks; b speed and code compactness on a wide range of platforms; and c designsimplicity; as well as its similarities and dissimilarities with other symmetric ciphers. On the other side, the principal advantages of new AES with respect to DES, as well as its limitations, are investigated. Thus, for example, the fact that the new cipher and its inverse use different components, which practically eliminates the possibility for weak and semi-weak keys, as existing for DES, and the non-linearity of the key expansion, which practically eliminates the possibility of equivalent keys, are two of the principal advantages of new cipher. Finally, the implementation aspects of Rijndael cipherand its inverse are treated. Thus, although Rijndael is well suited to be implemented efficiently on a wide range of processors and in dedicated hardware, we have concentrated our study on 8-bit processors, typical for current Smart Cards and on 32-bit processors, typical for PCs.

  16. Characterizing the Rigidly Rotating Magnetosphere Stars HD 345439 and HD 23478

    CERN Document Server

    Wisniewski, J P; Davenport, J R A; Bartz, J; Pepper, J; Whelan, D G; Eikenberry, S S; Lomax, J R; Majewski, S R; Richardson, N D; Skrutskie, M

    2015-01-01

    The SDSS III APOGEE survey recently identified two new $\\sigma$ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the KELT, SuperWASP, and ASAS surveys reveals the presence of a $\\sim$0.7701 day period in each dataset, suggesting the system is amongst the faster known $\\sigma$ Ori E analogs. We also see clear evidence that the strength of H-alpha, H I Brackett series lines, and He I lines also vary on a $\\sim$0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H I lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H I Br-11 ...

  17. The type IIb supernova 2013df and its cool supergiant progenitor

    Energy Technology Data Exchange (ETDEWEB)

    Van Dyk, Schuyler D. [Spitzer Science Center/Caltech, Mail Code 220-6, Pasadena, CA 91125 (United States); Zheng, WeiKang; Fox, Ori D.; Clubb, Kelsey I.; Filippenko, Alexei V.; Kelly, Patrick L. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Miller, Adam A. [Jet Propulsion Laboratory, MS 169-506, Pasadena, CA 91109 (United States); Smith, Nathan [Steward Observatory, University of Arizona, Tucson, AZ 85720 (United States); Lee, William H. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, Cd. Universitaria, México DF 04510 (Mexico); Ben-Ami, Sagi; Gal-Yam, Avishay, E-mail: vandyk@ipac.caltech.edu [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel)

    2014-02-01

    We have obtained early-time photometry and spectroscopy of supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less {sup 56}Ni (≲ 0.06 M {sub ☉}) was synthesized in the SN 2013df explosion than was the case for the SNe IIb 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013df is estimated to be A{sub V} = 0.30 mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope (HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 yr prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a red supergiant progenitor for a normal Type II-Plateau SN. From its observed spectral energy distribution, assuming that the light is dominated by one star, the progenitor had effective temperature T {sub eff} = 4250 ± 100 K and a bolometric luminosity L {sub bol} = 10{sup 4.94±0.06} L {sub ☉}. This leads to an effective radius R {sub eff} = 545 ± 65 R {sub ☉}. The star likely had an initial mass in the range of 13-17 M {sub ☉}; however, if it was a member of an interacting binary system, detailed modeling of the system is required to estimate this mass more accurately. The progenitor star of SN 2013df appears to have been relatively similar to the progenitor of SN 1993J.

  18. GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC3

    Science.gov (United States)

    Origlia, L.; Oliva, E.; Sanna, N.; Mucciarelli, A.; Dalessandro, E.; Scuderi, S.; Baffa, C.; Biliotti, V.; Carbonaro, L.; Falcini, G.; Giani, E.; Iuzzolino, M.; Massi, F.; Sozzi, M.; Tozzi, A.; Ghedina, A.; Ghinassi, F.; Lodi, M.; Harutyunyan, A.; Pedani, M.

    2016-01-01

    Aims: The Scutum complex in the inner disk of the Galaxy has a number of young star clusters dominated by red supergiants that are heavily obscured by dust extinction and observable only at infrared wavelengths. These clusters are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy. Methods: During the technical commissioning and as a first science verification of the GIANO spectrograph at the Telescopio Nazionale Galileo, we secured high-resolution (R ≃ 50 000) near-infrared spectra of five red supergiants in the young Scutum cluster RSGC3. Results: Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to measure several tens of atomic and molecular lines that were suitable for determining chemical abundances. By means of spectral synthesis and line equivalent width measurements, we obtained abundances of Fe and iron-peak elements such as Ni, Cr, and Cu, alpha (O, Mg, Si, Ca, Ti), other light elements (C, N, F, Na, Al, and Sc), and some s-process elements (Y, Sr). We found average half-solar iron abundances and solar-scaled [X/Fe] abundance patterns for most of the elements, consistent with a thin-disk chemistry. We found depletion of [C/Fe] and enhancement of [N/Fe], consistent with standard CN burning, and low 12C /13C abundance ratios (between 9 and 11), which require extra-mixing processes in the stellar interiors during the post-main sequence evolution. We also found local standard of rest VLSR = 106 km s-1 and heliocentric Vhel = 90 km s-1 radial velocities with a dispersion of 2.3 km s-1. Conclusions: The inferred radial velocities, abundances, and abundance patterns of RSGC3 are very similar to those previously measured in the other two young clusters of the Scutum complex, RSGC1 and RSGC2, suggesting a common kinematics and chemistry within the Scutum complex.

  19. GIANO-TNG spectroscopy of red supergiants in the young star cluster RSGC2

    Science.gov (United States)

    Origlia, L.; Oliva, E.; Maiolino, R.; Mucciarelli, A.; Baffa, C.; Biliotti, V.; Bruno, P.; Falcini, G.; Gavriousev, V.; Ghinassi, F.; Giani, E.; Gonzalez, M.; Leone, F.; Lodi, M.; Massi, F.; Montegriffo, P.; Mochi, I.; Pedani, M.; Rossetti, E.; Scuderi, S.; Sozzi, M.; Tozzi, A.

    2013-12-01

    Aims: The inner disk of the Galaxy has a number of young star clusters dominated by red supergiants that are heavily obscured by dust extinction and observable only at infrared wavelengths. These clusters are important tracers of the recent star formation and chemical enrichment history in the inner Galaxy. Methods: During the technical commissioning and as a first science verification of the GIANO spectrograph at the Telescopio Nazionale Galileo, we secured high-resolution (R ≃ 50 000) near-infrared spectra of three red supergiants in the young Scutum cluster RSGC2. Results: Taking advantage of the full YJHK spectral coverage of GIANO in a single exposure, we were able to identify several tens of atomic and molecular lines suitable for chemical abundance determinations. By means of spectral synthesis and line equivalent width measurements, we obtained abundances of Fe and other iron-peak elements such as V, Cr, Ni, of alpha (O, Mg, Si, Ca and Ti) and other light elements (C, N, Na, Al, K, Sc), and of some s-process elements (Y, Sr). We found iron abundances between half and one third solar and solar-scaled [X/Fe] abundance patterns of iron-peak, alpha and most of the light elements, consistent with a thin-disk chemistry. We found a depletion of [C/Fe] and enhancement of [N/Fe], consistent with CN burning, and low 12C/13C abundance ratios (between 9 and 11), requiring extra-mixing processes in the stellar interiors during the post-main-sequence evolution. Finally, we found a slight [Sr/Fe] enhancement and a slight [Y/Fe] depletion (by a factor of ≤2), with respect to solar. Table 3 is available in electronic form at http://www.aanda.org

  20. The Type IIb Supernova 2013df and its Cool Supergiant Progenitor

    Science.gov (United States)

    VanDyk, Schuyler D.; Zeng, Weikang; Fox, Ori D.; Cenko, S. Bradley; Clubb, Kelsey I.; Filippenko, Alexei; Foley, Ryan J.; Miller, Adam A.; Smith, Nathan; Kelly, Patrick L.; Lee, William H.; Ben-Ami, Sagi; Gal-Yam, Avishay

    2014-01-01

    We have obtained early-time photometry and spectroscopy of supernova (SN) 2013df in NGC 4414. The SN is clearly of Type II b, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less Ni-56 (is approximately less than 0.06M) was synthesized in the SN 2013df explosion than was the case for the SNe II b 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013dfis estimated to be A(sub V) = 0.30 mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope(HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 yr prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a red supergiant progenitor for a normal Type II-Plateau SN. From its observed spectral energy distribution, assuming that the light is dominated by one star, the progenitor had effective temperature T(sub eff) = 4250+/-100 K and a bolometric luminosity L(sub bol) =10(exp 4.94+/-0.06) Solar Luminosity. This leads to an effective radius Reff = 545+/-65 Solar Radius. The star likely had an initial mass in the range of 13-17Solar Mass; however, if it was a member of an interacting binary system, detailed modeling of the system is required to estimate this mass more accurately. The progenitor star of SN 2013df appears to have been relatively similar to the progenitor of SN 1993J.

  1. The study of acoustic emission (AE) forecasting coal and rock disaster technique

    Institute of Scientific and Technical Information of China (English)

    ZOU Yin-hui

    2009-01-01

    Introduced the coal and rock AE propagation rule, wave guide fixing technics on AE sensors, and AE forecasting coal and rock disaster on the scene and so on. The coal and rock AE propagation rule that follows the exponent attenuation function on different AE frequencies, different quality factors and different propagation distances were analyzed and deduced by theory, numerical simulation, and by actual experiment. Consequently, it was deduced that the coal and rock AE propagation rule follows the exponent attenuation function. Based on the correlative theory of wave dynamics and AE sensor, the AE wave guide propagation mechanical model on the sensor fixing manner is found, and the rela-tions of displacement and speed and acceleration between the AE signal source and the AE signal receiving terminal are presented. The effect of the AE sensor fixing manners on coal and rock surfaces, coal and rock bottoms and wave guides were studied by actual experiment. For the results, the effect of the AE sensor fixing manner on wave guides is better than on coal and rock surfaces, and was equivalent to the fixing manner on coal and rock bottoms. Based on the above study results, actual coal and rock dynamistic disasters were successfully forecasted.

  2. Characterisation of the magnetic fields of the Herbig Be stars HD 200775 and V380 0ri

    CERN Document Server

    Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J C; Donati, J F; Folsom, C P; Landstreet, J D; Silvester, J

    2006-01-01

    The origin of the magnetic fields of the chemically peculiar main sequence Ap/Bp stars is still matter of intense debate. The recent discoveries of magnetic fields in Herbig Ae/Be stars using high resolution data obtained with the spectropolarimeter ESPaDOnS at CFHT provide a strong argument in favour of the fossil field hypothesis. Using a simple oblique rotator model of a centered dipole, we fit the Stokes V LSD profiles of two of these magnetic HAeBe stars, HD 200775 and V380 Ori, as well as their variations on timescales from days to months. We find that in both cases the dipole hypothesis is acceptable and we determine the rotation period, the angle between rotation and magnetic axes and the intensity of the magnetic field at pole.

  3. The SPHERE view of the planet-forming disk around HD 100546

    Science.gov (United States)

    Garufi, A.; Quanz, S. P.; Schmid, H. M.; Mulders, G. D.; Avenhaus, H.; Boccaletti, A.; Ginski, C.; Langlois, M.; Stolker, T.; Augereau, J.-C.; Benisty, M.; Lopez, B.; Dominik, C.; Gratton, R.; Henning, T.; Janson, M.; Ménard, F.; Meyer, M. R.; Pinte, C.; Sissa, E.; Vigan, A.; Zurlo, A.; Bazzon, A.; Buenzli, E.; Bonnefoy, M.; Brandner, W.; Chauvin, G.; Cheetham, A.; Cudel, M.; Desidera, S.; Feldt, M.; Galicher, R.; Kasper, M.; Lagrange, A.-M.; Lannier, J.; Maire, A. L.; Mesa, D.; Mouillet, D.; Peretti, S.; Perrot, C.; Salter, G.; Wildi, F.

    2016-04-01

    Context. The mechanisms governing planet formation are not fully understood. A new era of high-resolution imaging of protoplanetary disks has recently started, thanks to new instruments such as SPHERE, GPI, and ALMA. The planet formation process can now be directly studied by imaging both planetary companions embedded in disks and their effect on disk morphology. Aims: We image disk features that could be potential signs of planet-disk interaction with unprecedented spatial resolution and sensitivity. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD 100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. Methods: We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD 100546 in scattered light. We obtained the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyzed with the pynpoint package. Results: The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to angular differential imaging processing) resembles a morphology newly observed in inclined disks. Given the cavity size in the visible (11 AU), the CO emission associated to the planet candidate c might arise from within the circumstellar disk. We find an extended emission in the K band at the expected location of b. The surrounding large-scale region is the brightest in scattered light. There is no sign of any disk gap associated to b. Based on data collected at the European Southern Observatory, Chile (ESO Programs 095.C-0273(A) and 095.C-0298(A)).

  4. H/D isotope effects in high temperature proton conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Huijser, A.; Poulsen, Finn Willy

    2015-01-01

    The atomic mass ratio of ca. 2 between deuterium and hydrogen is the highest for any pair of stable isotopes and results in significant and measurable H/D isotope effects in high temperature proton conductors containing these species. This paper discusses H/D isotope effects manifested in O......-H/O-D vibration frequencies, the mobility of H+/D+ carriers, the kinetics of the electrochemical oxidation of H2/D2, the solubilities of H2O/D2O and, finally, the spontaneous electromotive force that appears across H2/D2 cells with proton conducting electrolytes. Comparable work on tritium-exchanged materials...

  5. Differential asteroseismic study of seismic twins observed by CoRoT; Comparison of HD 175272 with HD 181420

    CERN Document Server

    Ozel, N; Dupret, M A; Bruntt, H; Barban, C; Deheuvels, S; Garc'\\ia, R A; Michel, E; Samadi, R; Baudin, F; Mathur, S; Régulo, C; Auvergne, M; Morel, P; Pichon, B

    2013-01-01

    The CoRoT short asteroseismic runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report the observation and modeling of the F5V star HD 175272. Our aim is to define a method for extracting as much information as possible from a noisy oscillation spectrum. We followed a differential approach that consists of using a well-known star as a reference to characterize another star. We used classical tools such as the envelope autocorrelation function to derive the global seismic parameters of the star. We compared HD 175272 with HD 181420 through a linear approach, because they appear to be asteroseismic twins. The comparison with the reference star enables us to substantially enhance the scientific output for HD 175272. First, we determined its global characteristics through a detailed seismic analysis of HD 181420. Second, with our differential approach, we measured the difference of mass, radius and age between HD 175272 and HD 181420. We have deve...

  6. Improving diffusion power of AES Rijndael with 8x8 MDS matrix

    Directory of Open Access Journals (Sweden)

    R.Elumalai,

    2011-01-01

    Full Text Available AES Rijndael is a block cipher developed by NIST as the Advanced Encryption Standard (AES replacing DES and published as FIPS 197 in November 2001 [5] to address the threatened key size of Data Encryption Standard (DES. AES-Rijndael was developed by Joan Daemen and Vincent Rijmen, Rijndael [4, 5] and was selected from five finalists. Advancement in computation speed every day puts lotsof pressure on AES and AES may not with stand attack for longer time. This work focuses on improving security of an encryption algorithm, beyond AES. Though there are various techniques available to enhance the security, an attempt is made to improve the diffusion strength of an algorithm. For enhancing the diffusion power AES Rijndael in MixColumn operation the branch number of MDS matrix is raised from 5 to 9 using a new 8X8 MDS matrix with trade off of speed [8, 9] and implemented on R8C microcontroller.

  7. Long-term soft X-ray characterization of Supergiant Fast X-ray Transients: the cumulative luminosity distributions

    CERN Document Server

    Bozzo, E; Ducci, L; Bernardini, F; Falanga, M

    2014-01-01

    We constructed the cumulative luminosity distributions of most supergiant fast X-ray transients (SFXTs) and the classical supergiant X-ray binary (SgXB) IGR J18027-2016 by taking advantage of the long term monitoring of these sources carried out with Swift/XRT (0.3-10 keV). Classical SgXBs are characterized by cumulative distributions with a single knee around $\\sim$10$^{36}$-10$^{37}$ erg/s, while all SFXTs are found to be significantly sub-luminous and the main knee in their distributions is shifted at lower luminosities ($$15 keV), we show that a soft X-ray monitoring is required to reconstruct the entire profile of the SFXT cumulative luminosity distributions. The difference between the cumulative luminosity distributions of classical SgXBs and SFXTs is interpreted in terms of different wind accretion modes.

  8. Gas lines from the 5-Myr old optically thin disk around HD141569A. Herschel observations and modeling

    CERN Document Server

    Thi, Wing-Fai; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Menard, Francois; Martin-Zaïdi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, Williams; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean

    2013-01-01

    At the distance of 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of OI at 63 and 145 micron and the CII line at 157 micron with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 micron, and 12CO fundamental ro-vibrational and pure rotational J=3-2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. The models suggest that the oxygen lines are emitted from the inner disk around HD141569A, whereas the [CII] line emission is more extended. The CO submillimeter fl...

  9. ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk

    CERN Document Server

    Walsh, Catherine; Meeus, Gwendolyn; Dent, William R F; Maud, Luke; Aikawa, Yuri; Millar, Tom J; Nomura, Hideko

    2016-01-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially-resolved observations at ~ mm wavelengths. We present the first spatially-resolved ~ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ~ 640 au. The ALMA data reveal a circular-symmetric dusty disk extending to ~ 350 au, and a molecular disk traced in CO J=3-2 emission, extending to ~ 750 au. The CO emission arises from a flared layer with an opening angle ~ 30 deg - 40 deg. HD 97048 is another source for which the large (~ mm-sized) dust grains are more centrally concentrated than the small (~ {\\mu}m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modelling suggests a decrement in continuum emission within ~ 50 au, consistent with the cavity size determined from mid-infrared imaging (34 +/- 4 au). The extracted continuum intensity profiles show ring-l...

  10. EFFECT OF PHOTODESORPTION ON THE SNOW LINES AT THE SURFACE OF OPTICALLY THICK CIRCUMSTELLAR DISKS AROUND HERBIG Ae/Be STARS

    International Nuclear Information System (INIS)

    We investigate the effect of photodesorption on the snow line position at the surface of a protoplanetary disk around a Herbig Ae/Be star, motivated by the detection of water ice particles at the surface of the disk around HD142527 by Honda et al. For this aim, we obtain the density and temperature structure in the disk with a 1+1D radiative transfer and determine the distribution of water ice particles in the disk by the balance between condensation, sublimation, and photodesorption. We find that photodesorption induced by far-ultraviolet radiation from the central star depresses the ice-condensation front toward the mid-plane and pushes the surface snow line significantly outward when the stellar effective temperature exceeds a certain critical value. This critical effective temperature depends on the stellar luminosity and mass, the water abundance in the disk, and the yield of photodesorption. We present an approximate analytic formula for the critical temperature. We separate Herbig Ae/Be stars into two groups on the HR diagram according to the critical temperature: one is the disks where photodesorption is effective and from which we may not find ice particles at the surface, and the other is the disks where photodesorption is not effective. We estimate the snow line position at the surface of the disk around HD142527 to be 100-300 AU, which is consistent with the water ice detection at >140 AU in the disk. All the results depend on the dust grain size in a complex way, and this point requires more work in the future.

  11. Practical Attacks on AES-like Cryptographic Hash Functions

    DEFF Research Database (Denmark)

    Kölbl, Stefan; Rechberger, Christian

    2015-01-01

    Despite the great interest in rebound attacks on AES-like hash functions since 2009, we report on a rather generic, albeit keyschedule-dependent, algorithmic improvement: A new message modification technique to extend the inbound phase, which even for large internal states makes it possible...... to drastically reduce the complexity of attacks to very practical values for reduced-round versions. Furthermore, we describe new and practical attacks on Whirlpool and the recently proposed GOST R hash function with one or more of the following properties: more rounds, less time/memory complexity, and more...

  12. Triafamone (AE 1887196) a new rice herbicide for Asia

    OpenAIRE

    Sato, Yoshitaka; Hacker, Erwin; Shirakura, Shinichi; Rosinger, Christopher; Heibkes, Silke; Nakamura Shin

    2012-01-01

    Triafamone (approved ISO common name) is a new sulfonanilide herbicide discovered and developed by Bayer CropScience AG under the code number AE 1887196. Its mode of action is inhibition of the enzyme acetolactate synthase (ALS). Field trials since 2007 have shown that triafamone can be effectively used in direct seeded or transplanted rice from seeding or transplanting to late post-emergence at rates of 20 to 50 g a.i./ha using spray or granular formulations. Target weeds are important grass...

  13. Radiative hydrodynamics simulations of red supergiant stars. III. Spectro-photocentric variability, photometric variability, and consequences on Gaia measurements

    OpenAIRE

    Chiavassa, A.; Pasquato, E.; Jorissen, A.; Sacuto, S.; Babusiaux, C.; Freytag, B.; Ludwig, H. -G.; Cruzalebes, P.; Rabbia, Y.; Spang, A.; Chesneau, O.

    2010-01-01

    Context. It has been shown that convection in red supergiant stars gives rise to large granules causing surface inhomogeneities together with shock waves in the photosphere. The resulting motion of the photocenter (on time scales ranging from months to years) could possibly have adverse effects on the parallax determination with Gaia. Aims. We explore the impact of the granulation on the photocentric and photometric variability. We quantify these effects in order to better characterize the er...

  14. 2D radiaition-hydrodynamic simulations of supernova shock breakout in bipolar explosions of a blue supergiant progenitor

    OpenAIRE

    Suzuki, Akihiro; Maeda, Keiichi; Shigeyama, Toshikazu

    2016-01-01

    A two-dimensional special relativistic radiation-hydrodynamics code is developed and applied to numerical simulations of supernova shock breakout in bipolar explosions of a blue supergiant. Our calculations successfully simulate the dynamical evolution of a blast wave in the star and its emergence from the surface. Results of the model with spherical energy deposition show a good agreement with previous simulations. Furthermore, we calculate several models with bipolar energy deposition and c...

  15. Genome Sequence of Bacillus thuringiensis subsp. kurstaki Strain HD-1

    OpenAIRE

    Day, Michael; Ibrahim, Mohamed; Dyer, David; Bulla, Lee

    2014-01-01

    We report here the complete genome sequence of Bacillus thuringiensis subsp. kurstaki strain HD-1, which serves as the primary U.S. reference standard for all commercial insecticidal formulations of B. thuringiensis manufactured around the world.

  16. HD 12098 and Other Results from Nainital–Cape Survey

    Indian Academy of Sciences (India)

    V. Girish

    2005-06-01

    Nainital;Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere.We discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD 12098 and briefly discuss the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.

  17. Asymmetric H-D exchange reactions of fluorinated aromatic ketones

    KAUST Repository

    Zhao, Yujun

    2012-01-01

    Chiral bicyclic guanidine catalyzes the asymmetric H-D exchange reactions. Up to 30% ee was achieved. DFT calculations were employed to elucidate and explain the origin of the reaction\\'s stereoselectivity. © 2012 The Royal Society of Chemistry.

  18. The VLT-FLAMES Tarantula Survey. XIX. B-type supergiants: Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequence

    OpenAIRE

    McEvoy, C. M.; Dufton, P. L.; Evans, C J; Kalari, V. M.; Markova, N.; Simón-Díaz, S.; Vink, J. S.; N. R. Walborn; Crowther, P. A.; Koter, de, A.; Mink, de, S.E.; Dunstall, P. R.; Hénault-Brunet, V.; Herrero, A.; Langer, N.

    2015-01-01

    Context. Model atmosphere analyses have been previously undertaken for both Galactic and extragalactic B-type supergiants. By contrast, little attention has been given to a comparison of the properties of single supergiants and those that are members of multiple systems. Aims. Atmospheric parameters and nitrogen abundances have been estimated for all the B-type supergiants identified in the VLT-FLAMES Tarantula survey. These include both single targets and binary candidates. The results h...

  19. The Puzzling Spectrum of HD 94509

    CERN Document Server

    Cowley, C R; Hubrig, S

    2015-01-01

    The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmo...

  20. Three Super-Earths Orbiting HD 7924

    CERN Document Server

    Fulton, Benjamin J; Sinukoff, Evan; Isaacson, Howard; Howard, Andrew W; Marcy, Geoffrey W; Henry, Gregory W; Holden, Bradford P; Kibrick, Robert I

    2015-01-01

    We report the discovery of two super-Earth mass planets orbiting the nearby K0.5 dwarf HD 7924 which was previously known to host one small planet. The new companions have masses of 7.9 and 6.4 M$_\\oplus$, and orbital periods of 15.3 and 24.5 days. We perform a joint analysis of high-precision radial velocity data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to robustly detect three total planets in the system. We refine the ephemeris of the previously known planet using five years of new Keck data and high-cadence observations over the last 1.3 years with the APF. With this new ephemeris, we show that a previous transit search for the inner-most planet would have covered 70% of the predicted ingress or egress times. Photometric data collected over the last eight years using the Automated Photometric Telescope shows no evidence for transits of any of the planets, which would be detectable if the planets transit and their compositions are hydrogen-dominated. We detect a long-period signa...

  1. MID-INFRARED IMAGING OF THE TRANSITIONAL DISK OF HD 169142: MEASURING THE SIZE OF THE GAP

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Mathematics and Physics, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Maaskant, Koen; Waters, L. B. F. M.; Dominik, C.; Mulders, G. D. [Astronomical Institute Anton Pannekoek, University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Okamoto, Y. K. [Institute of Astrophysics and Planetary Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Kataza, H. [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Fukagawa, M. [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Min, M. [Astronomical Institute Utrecht, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Yamashita, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Fujiyoshi, T.; Fujiwara, H. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Miyata, T.; Sako, S. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Sakon, I.; Onaka, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-06-20

    The disk around the Herbig Ae star HD 169142 was imaged and resolved at 18.8 and 24.5 {mu}m using Subaru/COMICS. We interpret the observations using a two-dimensional radiative transfer model and find evidence for the presence of a large gap. The mid-infrared images trace dust that is emitted at the onset of a strong rise in the spectral energy distribution (SED) at 20 {mu}m, and are therefore very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23{sup +3}{sub -5} AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the near-infrared, and an optically thin, geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a strong case for classification as a transitional disk, though improved imaging surveys are needed to support this speculation.

  2. Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap

    CERN Document Server

    Honda, M; Okamoto, Y K; Kataza, H; Fukagawa, M; Waters, L B F M; Dominik, C; Tielens, A G G M; Mulders, G D; Min, M; Yamashita, T; Fujiyoshi, T; Miyata, T; Sako, S; Sakon, I; Fujiwara, H; Onaka, T

    2012-01-01

    The disk around the Herbig Ae star HD\\,169142 was imaged and resolved at 18.8 and 24.5\\,$\\mu$m using Subaru/COMICS. We interpret the observations using a 2D radiative transfer model and find evidence for the presence of a large gap. The MIR images trace dust that emits at the onset of the strong rise in the spectral energy distribution (SED) at 20\\,$\\mu$m, therefore are very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23$^{+3}_{-5}$\\,AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the NIR and an optically thin geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a support for classifi...

  3. Bidirectional uncompressed HD video distribution over fiber employing VCSELs

    DEFF Research Database (Denmark)

    Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José; Rodes, G. A.;

    2012-01-01

    We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links.......We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links....

  4. Cometary grains in the HD 32297 debris disk

    Science.gov (United States)

    Yang, Y.-G.; Li, Aigen

    2016-07-01

    HD 32297 is a young A-type star with a bright edge-on debris disk. The dust thermal emission spectral energy distribution and scattered starlight spectrum are simultaneously modeled in terms of porous cometary grains. Our modeling suggests that, similar to the solar system, the debris disk around HD 32297 may have an inner warm ring and an outer cold disk which are seen in other young debris disks as well.

  5. Above-Threshold Dissociation of HD+ in Femtosecond Laser Field

    Institute of Scientific and Technical Information of China (English)

    BA Song-Yue; YUAN Kai-Jun; HAN Yong-Chang; CONG Shu-Lin

    2008-01-01

    @@ The above-threshold dissociation (ATD) of the HD+ molecular ion in femtosecond laser field is investigated theoretically. The energy-dependent distribution of the dissociated fragments is calculated using an asymptotic-flow expression in the momentum space. The calculations show that the ATD of HD+ is sensitive to the initial vibrational level of ground electronic state. Multiphoton ATDs can be observed in the dissociation processes. The dynamics phenomena are interpreted by using the concept of light-dressed potential.

  6. The impact of mass-loss on the evolution and pre-supernova properties of red supergiants

    CERN Document Server

    Meynet, G; Ekström, S; Georgy, C; Granada, A; Groh, J; Maeder, A; Eggenberger, P; Levesque, E; Massey, P

    2014-01-01

    The post main-sequence evolution of massive stars is very sensitive to many parameters of the stellar models. Key parameters are the mixing processes, the metallicity, the mass-loss rate and the effect of a close companion. We study how the red supergiant lifetimes, the tracks in the Hertzsprung-Russel diagram (HRD), the positions in this diagram of the pre-supernova progenitor as well as the structure of the stars at that time change for various mass-loss rates during the red supergiant phase (RSG), and for two different initial rotation velocities. The surface abundances of RSGs are much more sensitive to rotation than to the mass-loss rates during that phase. A change of the RSG mass-loss rate has a strong impact on the RSG lifetimes and therefore on the luminosity function of RSGs. At solar metallicity, the enhanced mass-loss rate models do produce significant changes on the populations of blue, yellow and red supergiants. When extended blue loops or blue ward excursions are produced by enhanced mass-loss...

  7. Red Supergiant Stars as Cosmic Abundance Probes: NLTE Effects in J-band Iron and Titanium Lines

    CERN Document Server

    Bergemann, Maria; Plez, Bertrand; Davies, Ben; Lind, Karin; Gazak, Zach

    2012-01-01

    Detailed non-LTE calculations for red supergiant stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J-band. With their enormous brightness at J-band red supergiant stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium resolution spectroscopy of individual red supergiants in galaxies as distant as 10 Mpc. The non-LTE results obtained in this investigation support these findings. Non-LTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400K to 4200K and 0.1 dex at 4400K. For titanium the non-LTE abundance corrections vary smoothly between -0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the non-LTE corrections and the consequences for extragalactic J-band abundance studies are discussed.

  8. Ring Nebula and Bipolar Outflows Associated with the B1.5 Supergiant Sher #25 in NGC 3603

    CERN Document Server

    Brandner, W; Chu, Y H; Weis, K; Brandner, Wolfgang; Grebel, Eva K.; Chu, You-Hua; Weis, Kerstin

    1996-01-01

    We have identified a ring-shaped emission-line nebula and a possible bipolar outflow centered on the B1.5 supergiant Sher #25 in the Galactic giant HII region NGC 3603 (distance 6 kpc). The clumpy ring around Sher #25 appears to be tilted by 64 deg against the plane of the sky. Its semi-major axis (position angle approx. 165 deg) is 6.9" long, which corresponds to a ring diameter of 0.4 pc. The bipolar outflow filaments, presumably located above and below the ring plane on either side of Sher #25, show a separation of approx. 0.5 pc from the central star. High-resolution spectra show that the ring has a systemic velocity of V_LSR = +19 km/s and a de-projected expansion velocity of 20 km/s, and that one of the bipolar filaments has an outflow speed of approx. 83 km/s. The spectra also show high [NII]/Halpha ratio, suggestive of strong N enrichment. Sher #25 must be an evolved blue supergiant (BSG) past the red supergiant (RSG) stage. We find that the ratio of equatorial to polar mass-loss rate during the red s...

  9. On the H$\\alpha$ Behaviour of Blue Supergiants: Rise and Fall over the Bi-stability Jump

    CERN Document Server

    Petrov, Blagovest; Gräfener, Götz

    2014-01-01

    The evolutionary state of blue supergiants is still unknown. Stellar wind mass loss is one of the dominant processes determining the evolution of massive stars, and it may provide clues on the evolutionary properties of blue supergiants. As the H$\\alpha$ line is the most oft-used mass-loss tracer in the OB-star regime, we provide a detailed analysis of the H$\\alpha$ line for OB supergiant models over an $T_{\\rm eff}$ range between 30000 and 12500K. We find a maximum in the H$\\alpha$ equivalent width at 22500 K - at the location of the bi-stability jump. The H$\\alpha$ line-profile behaviour is characterised by two branches of $T_{\\rm eff}$: (i) a "hot" branch between 30000 and 22500 K, where H$\\alpha$ emission becomes stronger with decreasing $T_{\\rm eff}$, and (ii) a "cool" branch between 22500 and 12500 K, where the line becomes weaker. Our models show that this non-monotonic H$\\alpha$ behaviour is related to the optical depth of Ly$\\alpha$, finding that at the "cool" branch the population of the 2nd level o...

  10. A Dark Energy Camera Search for Missing Supergiants in the LMC After the Advanced LIGO Gravitational Wave Event GW150914

    CERN Document Server

    Annis, J; Berger, E; Brout, D; Chen, H; Chornock, R; Cowperthwaite, P S; Diehl, H T; Doctor, Z; Drlica-Wagner, A; Drout, M R; Farr, B; Finley, D A; Flaugher, B; Foley, R J; Frieman, J; Gruendl, R A; Herner, K; Holz, D; Kessler, R; Lin, H; Marriner, J; Neilsen, E; Rest, A; Sako, M; Smith, M; Smith, N; Sobreira, F; Walker, A R; Yanny, B; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Bernstein, R A; Bertin, E; Buckley-Geer, E; Burke, D L; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Castander, F J; Cenko, S B; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Dietrich, J P; Eifler, T F; Evrard, A E; Fernandez, E; Fischer, J; Fong, W; Fosalba, P; Fox, D B; Fryer, C L; Garcia-Bellido, J; Gaztanaga, E; Gerdes, D W; Goldstein, D A; Gruen, D; Gutierrez, G; Honscheid, K; James, D J; Karliner, I; Kasen, D; Kent, S; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Lima, M; Maia, M A G; Martini, P; Metzger, B D; Miller, C J; Miquel, R; Mohr, J J; Nichol, R C; Nord, B; Ogando, R; Peoples, J; Plazas, A A; Quataert, E; Romer, A K; Roodman, A; Rykoff, E S; Sanchez, E; Santiago, B; Scarpine, V; Schindler, R; Schubnell, M; Sevilla-Noarbe, I; Sheldon, E; Smith, R C; Stebbins, A; Swanson, M E C; Tarle, G; Thaler, J; Thomas, R C; Tucker, D L; Vikram, V; Wechsler, R H; Weller, J; Wester, W

    2016-01-01

    The collapse of the core of a star is expected to produce gravitational radiation. While this process will usually produce a luminous supernova, the optical signatue could be subluminous and a direct collapse to a black hole, with the star just disappearing, is possible. The gravitational wave event GW150914 reported by the LIGO Virgo Collaboration (LVC) on 2015 September 16, was detected by a burst analysis and whose high probability spatial localization included the Large Magellanic Cloud. Shortly after the announcement of the event, we used the Dark Energy Camera to observe 102 deg$^2$ of the localization area, including a 38 deg$^2$ area centered on the LMC. Using a catalog of 152 LMC luminous red supergiants, candidates to undergo a core collapse without a visible supernova, we find that the positions of 144 of these are inside our images, and that all are detected - none have disappeared. There are other classes of candidates: we searched existing catalogs of red supergiants, yellow supergiants, Wolf-Ra...

  11. ALMA detection of the rotating molecular disk wind drom the young star HD 163296

    CERN Document Server

    Klaassen, P D; Mathews, G S; De Gregorio-Monsalvo, J C Mottram I; van Dishoeck, E F; Takahashi, S; Akiyama, E; Chapillon, E; Espada, D; Hales, A; Hogerheijde, M R; Rawlings, M; Schmalzl, M; Testi, L

    2013-01-01

    Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew morphology and extends more than 10" from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet which is moving at much higher velocities. We show that the J=3-2 emission is likely heavily filtered by the interferometer, but the J=2-1 emission suffers less due to the larger beam and measurable angular scales. Excitation analysis suggests temperatures...

  12. Unveiling the gas and dust disk structure in HD 163296 using ALMA observations

    CERN Document Server

    de Gregorio-Monsalvo, I; Dent, W; Pinte, C; López, C; Klaassen, P; Hales, A; Cortés, P; Rawlings, M G; Tachihara, K; Testi, L; Takahashi, S; Chapillon, E; Mathews, G; Juhasz, A; Akiyama, E; Higuchi, A E; Saito, M; Nyman, L - Å; Phillips, N; Rodń, J; Corder, S; Van Kempen, T

    2013-01-01

    Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We have used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 microns, as well as the 3- dimensional radiative transfer code MCFOST to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at sub-millimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back- and the front-side of a flared disk. Continuum emission at 850 microns reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirms the need for a sharp outer edge to the dust disk. The models for the ...

  13. Resolving the CO Snow Line in the Disk around HD 163296

    CERN Document Server

    Qi, Chunhua; Oberg, Karin I; Wilner, David J; Hughes, A Meredith; Andrews, Sean M; Ayala, Sandra

    2011-01-01

    We report Submillimeter Array (SMA) observations of CO (J=2--1, 3--2 and 6--5) and its isotopologues (13CO J=2--1, C18O J=2--1 and C17O J=3--2) in the disk around the Herbig Ae star HD 163296 at ~2" (250 AU) resolution, and interpret these data in the framework of a model that constrains the radial and vertical location of the line emission regions. First, we develop a physically self-consistent accretion disk model with an exponentially tapered edge that matches the spectral energy distribution and spatially resolved millimeter dust continuum emission. Then, we refine the vertical structure of the model using wide range of excitation conditions sampled by the CO lines, in particular the rarely observed J=6--5 transition. By fitting 13CO data in this structure, we further constrain the vertical distribution of CO to lie between a lower boundary below which CO freezes out onto dust grains (T ~ 19 K) and an upper boundary above which CO can be photodissociated (the hydrogen column density from the disk surface ...

  14. Pre-main-sequence binaries with tidally disrupted discs: the Br gamma in HD 104237

    CERN Document Server

    Garcia, P J V; Dougados, C; Bacciotti, F; Clausse, J -M; Massi, F; Mérand, A; Petrov, R; Weigelt, G

    2013-01-01

    Active pre-main-sequence binaries with separations of around ten stellar radii present a wealth of phenomena unobserved in common systems. The study of these objects is extended from Classical T Tauri stars to the Herbig Ae star HD 104237. Spectro-interferometry with the VLTI/AMBER is presented. It is found that the K-band continuum squared visibilities are compatible with a circumbinary disc with a radius of ~0.5 AU. However, a significant fraction (~50 per cent) of the flux is unresolved and not fully accounted by the stellar photospheres. The stars probably don't hold circumstellar discs, in addition to the circumbinary disk, due to the combined effects of inner magnetospheric truncation and outer tidal truncation. This unresolved flux likely arises in compact structures inside the tidally disrupted circumbinary disc. Most ($\\gtrsim 90$ per cent) of the Br gamma line emission is unresolved. The line-to-continuum spectro-astrometry shifts in time, along the direction of the Ly alpha jet known to be driven b...

  15. Chemical Imaging of the CO Snow Line in the HD 163296 Disk

    CERN Document Server

    Qi, Chunhua; Andrews, Sean M; Wilner, David J; Bergin, Edwin A; Hughes, A Meredith; Hogherheijde, Michiel; D'Alessio, Paola

    2015-01-01

    The condensation fronts (snow lines) of H2O, CO and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density is expected to drop substantially, based solely on CO emission profiles is challenging. This has prompted an exploration of chemical signatures of CO freeze-out. We present ALMA Cycle 1 observations of the N2H+ J=3-2 and DCO+ J=4-3 emission lines toward the disk around the Herbig Ae star HD~163296 at ~0.5" (60 AU) resolution, and evaluate their utility as tracers of the CO snow line location. The N2H+ emission is distributed in a ring with an inner radius at 90 AU, corresponding to a midplane temperature of 25 K. This result is consistent with a new analysis of optically thin C18O data, which implies a sharp drop in CO abundance at 90 AU. Thus N2H+ appears to be a robust tracer of the midplane CO snow line. The DCO+ emission also has a ring morphology, but neither the inner nor the outer radi...

  16. A SPATIALLY RESOLVED VERTICAL TEMPERATURE GRADIENT IN THE HD 163296 DISK

    International Nuclear Information System (INIS)

    We analyze sensitive, sub-arcsecond resolution ALMA science verification observations of CO emission lines in the protoplanetary disk hosted by the young, isolated Ae star HD 163296. The observed spatial morphology of the 12CO J = 3-2 emission line is asymmetric across the major axis of the disk; the 12CO J = 2-1 line features a much less pronounced, but similar, asymmetry. The J = 2-1 emission from 12CO and its main isotopologues have no resolved spatial asymmetry. We associate this behavior with the direct signature of a vertical temperature gradient and layered molecular structure in the disk. This is demonstrated using both toy models and more sophisticated calculations assuming non-local thermodynamic equilibrium conditions. A model disk structure is developed to reproduce both the distinctive spatial morphology of the 12CO J = 3-2 line as well as the J = 2-1 emission from the CO isotopologues assuming relative abundances consistent with the interstellar medium. This model disk structure has τ = 1 emitting surfaces for the 12CO emission lines that make an angle of ∼15° with respect to the disk midplane. Furthermore, we show that the spatial and spectral sensitivity of these data can distinguish between models that have sub-Keplerian gas velocities due to the vertical extent of the disk and its associated radial pressure gradient (a fractional difference in the bulk gas velocity field of ∼> 5%)

  17. Structures in the protoplanetary disk of HD142527 seen in polarized scattered light

    CERN Document Server

    Avenhaus, Henning; Schmid, Hans Martin; Meyer, Michael R; Garufi, Antonio; Wolf, Sebastian; Dominik, Carsten

    2013-01-01

    We present H- and Ks-band polarized differential images (PDI) of the Herbig Ae/Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (~0.1") and high resolution achievable with an 8m-class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered light images. Previously known substructures are resolved more clearly and new structures are seen. Specifically, we are able to resolve 1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiral arms and arcs close to the inner rim of the disk; 2) peculiar holes in the polarized surface brightness at position angles of ~0{\\deg} and ~160{\\deg}; 3) the inner rim on the eastern side of the disk; 4) the gap between the outer and inner disk, ranging from the inner working angle of 0.1" out to between 0.7 and 1.0", which is nearly devoid of dust. We then use a Markov-...

  18. Warm H2O and OH in the disk around the Herbig star HD 163296

    CERN Document Server

    Fedele, D; van Dishoeck, E F; Herczeg, G J; Evans, N J; Bouwman, J; Henning, Th; Green, J

    2012-01-01

    We present observations of far-infrared (50-200 micron) OH and H2O emission of the disk around the Herbig Ae star HD 163296 obtained with Herschel/PACS in the context of the DIGIT key program. In addition to strong [OI] emission, a number of OH doublets and a few weak highly excited lines of H2O are detected. The presence of warm H2O in this Herbig disk is confirmed by a line stacking analysis, enabled by the full PACS spectral scan, and by lines seen in Spitzer data. The line fluxes are analyzed using an LTE slab model including line opacity. The water column density is 10^14 - 10^15 cm^-2, and the excitation temperature is 200-300 K implying warm gas with a density n > 10^5 cm^-3. For OH we find a column density of 10^14 - 2x10^15 cm^-2 and T_ex ~ 300-500 K. For both species we find an emitting region of r ~ 15-20 AU from the star. We argue that the molecular emission arises from the protoplanetary disk rather than from an outflow. This far-infrared detection of both H2O and OH contrasts with near- and mid-...

  19. Unix环境下编译调试HD Photo%Compiling and Debugging HD PHOTO Based on Unix Environment

    Institute of Scientific and Technical Information of China (English)

    朱海华

    2009-01-01

    微软公司自行研发了HD Photo图片格式,HD Photo可以支持高达32 bit的色彩深度.在Windows系统中使用Cygwin工具构造Unix虚拟环境,配置编译HD Photo所需要的编译环境,然后用这个编译环境对HD Photo工具包内的编解码算法进行编译,并产生二进制可执行文件.通过可视化GDB工具Insight对可执行文件进行调试,可以用Insight连接终端设备并将可执行文件下载到终端设备上.

  20. Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b

    CERN Document Server

    Moses, Julianne I; Fortney, Jonathan J; Showman, Adam P; Lewis, Nikole K; Griffith, Caitlin A; Shabram, Megan; Friedson, A James; Marley, Mark S; Freedman, Richard S

    2011-01-01

    We have developed 1-D photochemical and thermochemical kinetics and diffusion models for the transiting exoplanets HD 189733b and HD 209458b to study the effects of disequilibrium chemistry on the atmospheric composition of "hot Jupiters." Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species, and we compare the model results with existing transit and eclipse observations. We find that the vertical profiles of molecular constituents are significantly affected by transport-induced quenching and photochemistry, particularly on cooler HD 189733b; however, the warmer stratospheric temperatures on HD 209458b can help maintain thermochemical equilibrium and reduce the effects of disequilibrium chemistry. For both planets, the methane and ammonia mole fractions are found to be enhanced over their equilibrium values at pressures of a few bar to less than a mbar due to transport-induced quenching, but CH$_4$ and NH$_3$ are photochemically removed at higher altitudes. Atomi...

  1. Analytical role of sodium dodecyl sulphate in icp-aes

    International Nuclear Information System (INIS)

    Effect of Sodium Dodecyl Sulphate (SDS) on sample transport efficiency, nebulisation and overall contribution in analysis using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for different analytes has been studied. The objective of this study was to investigate the effect of surfactant on the quality of aerosols results in enhancement or depression of the final analyte signals The SDS is anionic in nature, has been added to set of standards containing Cr, Fe, Co, Ni, Cu, Cd and Pb in the presence of 0.01% - 2.0% HNO/sub 3/. Typical property of surfactants i.e. lowering of surface tension has been exploited to modify the analytical procedures for analysis through ICP-AES. Determinations were carried out using 5 ppm analytes under a set of conditions i.e. below Critical Micelle Concentration (CMC) at CMC and above CMC of the surfactant used. All glass Meinhard pneumatic nebuliser was used for the nebulisation processes. The results have been explained on the basis of a mild action of the surfactants to modify the plasma analytical conditions due to the change in the overall physical parameters. (author)

  2. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star?

    Science.gov (United States)

    Alecian, E.; Neiner, C.; Mathis, S.; Catala, C.; Kochukhov, O.; Landstreet, J.

    2013-01-01

    In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman signature on timescales of days to weeks, indicating that the configuration of its field has changed between 2009 and 2011. Such a sudden change of external structure of a fossil field has never previously been observed in any intermediate or high-mass star. HD 190073 is an almost entirely radiative pre-main sequence star, probably hosting a growing convective core. We propose that this dramatic change is the result of the interaction between the fossil field and the ignition of a dynamo field generated in the newly-born convective core. Based on observations collected at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers (INSU) of the Centre National de la Recherche Scientifique (CNRS) of France and the University of Hawaii, at the Observatoire du Pic du Midi (France), operated by INSU, and at the European Southern Observatory, Chile (Program ID 187.D-0917).

  3. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ?

    CERN Document Server

    Alecian, E; Mathis, S; Catala, C; Kochukhov, O; Landstreet, J

    2013-01-01

    In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman signature on timescales of days to weeks, indicating that the configuration of its field has changed between 2009 and 2011. Such a sudden change of external structure of a fossil field has never previously been observed in any intermediate or high-mass star. HD 190073 is an almost entirely radiative pre-main sequence star, probably hosting a growing convective core. We propose that this dramatic change is the result of the interaction between the fossil field and the ignition of a dynamo field generated in the newly-born ...

  4. Numerical predictions for planets in the debris discs of HD 202628 and HD 207129

    CERN Document Server

    Thilliez, E

    2016-01-01

    Resolved debris disc images can exhibit a range of radial and azimuthal structures, including gaps and rings, which can result from planetary companions shaping the disc by their gravitational influence. Currently there are no tools available to determine the architecture of potential companions from disc observations. Recent work by Rodigas et al. (2014) presents how one can estimate the maximum mass and minimum semi major axis of a hidden planet empirically from the width of the disc in scattered light. In this work, we use the predictions of Rodigas et al. applied to two debris discs HD 202628 and HD 207129. We aim to test if the predicted orbits of the planets can explain the features of their debris disc, such as eccentricity and sharp inner edge. We first run dynamical simulations using the predicted planetary parameters of Rodigas et al., and then numerically search for better parameters. Using a modified N-body code including radiation forces, we perform simulations over a broad range of planet parame...

  5. Inhomogeneous molecular ring around the B[e] supergiant LHA 120-S 73

    CERN Document Server

    Kraus, M; Arias, M L; Maravelias, G; Nickeler, D H; Torres, A F; Fernandes, M Borges; Aret, A; Cure, M; Vallverdu, R; Barba, R H

    2016-01-01

    We aim to improve our knowledge on the structure and dynamics of the circumstellar disk of the LMC B[e] supergiant LHA 120-S 73. High-resolution optical and near-IR spectroscopic data were obtained over a period of 16 and 7 years, respectively. The spectra cover the diagnostic emission lines from [CaII] and [OI], as well as the CO bands. These features trace the disk at different distances from the star. We analyzed the kinematics of the individual emission regions by modeling their emission profiles. A low-resolution mid-infrared spectrum was obtained as well, which provides information on the composition of the dusty disk. All diagnostic emission features display double-peaked line profiles, which we interpret as due to Keplerian rotation. We find that LHA 120-S 73 is surrounded by at least four individual rings of material with alternating densities (or by a disk with strongly non-monotonic radial density distribution). Moreover, we find that the molecular ring must have gaps or at least strong density inh...

  6. The Type IIb Supernova 2013df and Its Cool Supergiant Progenitor

    CERN Document Server

    Van Dyk, Schuyler D; Fox, Ori D; Cenko, S Bradley; Clubb, Kelsey I; Filippenko, Alexei V; Foley, Ryan J; Miller, Adam A; Smith, Nathan; Kelly, Patrick L; Lee, William H; Ben-Ami, Sagi; Gal-Yam, Avishay

    2013-01-01

    We have obtained early-time photometry and spectroscopy of Supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less $^{56}$Ni ($\\lesssim 0.06\\ M_{\\odot}$) was synthesized in the SN 2013df explosion than was the case for the SNe IIb 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013df is estimated to be $A_V=0.30$ mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope (HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 years prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a ...

  7. The eclipsing, double-lined, Of supergiant binary Cygnus OB2-B17

    Science.gov (United States)

    Stroud, V. E.; Clark, J. S.; Negueruela, I.; Roche, P.; Norton, A. J.; Vilardell, F.

    2010-02-01

    Context. Massive, eclipsing, double-lined, spectroscopic binaries are not common but are necessary to understand the evolution of massive stars as they are the only direct way to determine stellar masses. They are also the progenitors of energetic phenomena such as X-ray binaries and γ-ray bursts. Aims: We present a photometric and spectroscopic analysis of the candidate binary system Cyg OB2-B17 to show that it is indeed a massive evolved binary. Methods: We utilise V band and white-light photometry to obtain a light curve and period of the system, and spectra at different resolutions to calculate preliminary orbital parameters and spectral classes for the components. Results: Our results suggest that B17 is an eclipsing, double-lined, spectroscopic binary with a period of 4.0217±0.0004 days, with two massive evolved components with preliminary classifications of O7 and O9 supergiants. The radial velocity and light curves are consistent with a massive binary containing components with similar luminosities, and in turn with the preliminary spectral types and age of the association.

  8. The eclipsing, double-lined, Of supergiant binary Cyg OB2-B17

    CERN Document Server

    Stroud, V E; Negueruela, I; Roche, P; Norton, A J; Vilardell, F

    2010-01-01

    Massive, eclipsing, double-lined, spectroscopic binaries are not common but are necessary to understand the evolution of massive stars as they are the only direct way to determine stellar masses. They are also the progenitors of energetic phenomena such as X-ray binaries and gamma-ray bursts. We present a photometric and spectroscopic analysis of the candidate binary system Cyg OB2-B17 to show that it is indeed a massive evolved binary. We utilise V band and white-light photometry to obtain a light curve and period of the system, and spectra at different resolutions to calculate preliminary orbital parameters and spectral classes for the components. Our results suggest that B17 is an eclipsing, double-lined, spectroscopic binary with a period of 4.0217+/-0.0004 days, with two massive evolved components with preliminary classifications of O7 and O9 supergiants. The radial velocity and light curves are consistent with a massive binary containing components with similar luminosities, and in turn with the prelimi...

  9. X-ray, UV and optical analysis of supergiants: $\\epsilon$ Ori

    CERN Document Server

    Puebla, Raul E; Zsargó, Janos; Cohen, David H; Leutenegger, Maurice A

    2015-01-01

    We present a multi-wavelength (X-ray to optical) analysis, based on non-local thermodynamic equilibrium photospheric+wind models, of the B0 Ia-supergiant: $\\epsilon$~Ori. The aim is to test the consistency of physical parameters, such as the mass-loss rate and CNO abundances, derived from different spectral bands. The derived mass-loss rate is $\\dot{M}/\\sqrt{f_\\infty}\\sim$1.6$\\times$10$^{-6}$ M$_\\odot$ yr$^{-1}$ where $f_\\infty$ is the volume filling factor. However, the S IV $\\lambda\\lambda$1062,1073 profiles are too strong in the models; to fit the observed profiles it is necessary to use $f_\\infty<$0.01. This value is a factor of 5 to 10 lower than inferred from other diagnostics, and implies $\\dot{M} \\lesssim1 \\times 10^{-7}$ M$_\\odot$ yr$^{-1}$. The discrepancy could be related to porosity-vorosity effects or a problem with the ionization of sulfur in the wind. To fit the UV profiles of N V and O VI it was necessary to include emission from an interclump medium with a density contrast ($\\rho_{cl}/\\rho...

  10. Interferometric observations of the supergiant stars alpha Orionis and alpha Herculis with FLUOR at IOTA

    CERN Document Server

    Perrin, G; Foresto, V C; Mennesson, B; Traub, W A; Lacasse, M G

    2004-01-01

    We report the observations in the K band of the red supergiant star alpha Orionis and of the bright giant star alpha Herculis with the FLUOR beamcombiner at the IOTA interferometer. The high quality of the data allows us to estimate limb-darkening and derive precise diameters in the K band which combined with bolometric fluxes yield effective temperatures. In the case of Betelgeuse, data collected at high spatial frequency although sparse are compatible with circular symmetry and there is no clear evidence for departure from circular symmetry. We have combined the K band data with interferometric measurements in the L band and at 11.15 micron. The full set of data can be explained if a 2055 K layer with optical depths $\\tau_{K}=0.060\\pm0.003$, $\\tau_{L}=0.026\\pm0.002$ and $\\tau_{11.15\\mu m}=2.33\\pm0.23$ is added 0.33 $R_{\\star}$ above the photosphere providing a first consistent view of the star in this range of wavelengths. This layer provides a consistent explanation for at least three otherwise puzzling ob...

  11. ALMA observations of the supergiant B[e] star Wd1-9

    CERN Document Server

    Fenech, D; Prinja, R K; Morford, J C; Dougherty, S; Blomme, R

    2016-01-01

    Mass-loss in massive stars plays a critical role in their evolution, although the precise mechanism(s) responsible - radiatively driven winds, impulsive ejection and/or binary interaction -remain uncertain. In this paper we present ALMA line and continuum observations of the supergiant B[e] star Wd1-9, a massive post-Main Sequence object located within the starburst cluster Westerlund 1. We find it to be one of the brightest stellar point sources in the sky at millimetre wavelengths, with (serendipitously identified) emission in the H41alpha radio recombination line. We attribute these properties to a low velocity (~100 km/s) ionised wind, with an extreme mass-loss rate 6.4x10^-5(d/5kpc)^1.5 Msol/yr. External to this is an extended aspherical ejection nebula indicative of a prior phase of significant mass-loss. Taken together, the millimetre properties of Wd1-9 show a remarkable similarity to those of the highly luminous stellar source MWC349A.We conclude that these objects are interacting binaries evolving a...

  12. Monitoring Supergiant Fast X-ray Transients with Swift. Results from the first year

    CERN Document Server

    Romano, P; Cusumano, G; La Parola, V; Vercellone, S; Pagani, C; Ducci, L; Mangano, V; Cummings, J; Krimm, H A; Guidorzi, C; Kennea, J A; Hoversten, E A; Burrows, D N; Gehrels, N

    2009-01-01

    Swift has allowed the possibility to give Supergiant Fast X-ray Transients (SFXTs), the new class of High Mass X-ray Binaries discovered by INTEGRAL, non serendipitous attention throughout all phases of their life. We present our results based on the first year of intense Swift monitoring of four SFXTs, IGR J16479-4514, XTE J1739-302, IGR J17544-2619 and AX J1841.0-0536. We obtain the first assessment of how long each source spends in each state using a systematic monitoring with a sensitive instrument. The duty-cycle of inactivity is 17, 28, 39, 55% (5% uncertainty), for IGR J16479-4514, AX J1841.0-0536, XTE J1739-302, and IGR J17544-2619, respectively, so that true quiescence is a rare state. This demonstrates that these transients accrete matter throughout their life at different rates. AX J1841.0-0536 is the only source which has not undergone a bright outburst during our campaign. Although individual sources behave somewhat differently, common X-ray characteristics of this class are emerging such as outb...

  13. Quantitative spectroscopic J-band study of red supergiants in Perseus OB-1

    Energy Technology Data Exchange (ETDEWEB)

    Gazak, J. Zachary; Kudritzki, Rolf [Institute for Astronomy, University of Hawai' i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Davies, Ben [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Bergemann, Maria [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Plez, Bertrand [Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS, F-34095 Montpellier (France)

    2014-06-10

    We demonstrate how the metallicities of red supergiant (RSG) stars can be measured from quantitative spectroscopy down to resolutions of ≈3000 in the J-band. We have obtained high resolution spectra on a sample of the RSG population of h and χ Persei, a double cluster in the solar neighborhood. We show that careful application of the MARCS model atmospheres returns measurements of Z consistent with solar metallicity. Using two grids of synthetic spectra–one in pure LTE and one with non-LTE (NLTE) calculations for the most important diagnostic lines–we measure Z = +0.04 ± 0.10 (LTE) and Z = –0.04 ± 0.08 (NLTE) for the sample of eleven RSGs in the cluster. We degrade the spectral resolution of our observations and find that those values remain consistent down to resolutions of less than λ/δλ of 3000. Using measurements of effective temperatures we compare our results with stellar evolution theory and find good agreement. We construct a synthetic cluster spectrum and find that analyzing this composite spectrum with single-star RSG models returns an accurate metallicity. We conclude that the RSGs make ideal targets in the near infrared for measuring the metallicities of star forming galaxies out to 7-10 Mpc and up to 10 times farther by observing the integrated light of unresolved super star clusters.

  14. Photometric and Spectroscopic Study of the Supergiant with an Infrared Excess V1027 Cygni

    CERN Document Server

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

    2016-01-01

    We present the results of our $UBV$ and $JHKLM$-photometry for the semiregular pulsating variable V1027~Cyg, a supergiant with an infrared excess, over the period from 1991 to 2015. Our search for a periodicity in the $UBV$ brightness variations has led to several periods from $P=212^{d}$ to $P=320^{d}$ in different time intervals. We have found the period $P=237^{d}$ based on our infrared photometry. The variability amplitude, the light-curve shape, and the magnitude of V1027~Cyg at maximum light change noticeably from cycle to cycle. An ambiguous correlation of the $B-V$ and $U-B$ colors with the brightness has been revealed. The spectral energy distribution for V1027~Cyg from our photometry in the range 0.36 ($U$)-5.0 ($M$) $\\mu$m corresponds to spectral types from G8I to K3I at different phases of the pulsation cycle. Low-resolution spectra of V1027 Cyg in the range $\\lambda$4400--9200 \\AA\\ were taken during 16 nights over the period 1995--2015. At the 1995 and 2011 photometric minima the star's spectrum ...

  15. INTEGRAL study of temporal properties of bright flares in Supergiant Fast X-ray Transients

    CERN Document Server

    Sidoli, L; Postnov, K

    2016-01-01

    We have characterized the typical temporal behaviour of the bright X-ray flares detected from the three Supergiant Fast X-ray Transients showing the most extreme transient behaviour (XTEJ1739-302, IGRJ17544-2619, SAXJ1818.6-1703). We focus here on the cumulative distributions of the waiting-time (time interval between two consecutive X-ray flares), and the duration of the hard X-ray activity (duration of the brightest phase of an SFXT outburst), as observed by INTEGRAL/IBIS in the energy band 17-50 keV. Adopting the cumulative distribution of waiting-times, it is possible to identify the typical timescale that clearly separates different outbursts, each composed by several single flares at ks timescale. This allowed us to measure the duration of the brightest phase of the outbursts from these three targets, finding that they show heavy-tailed cumulative distributions. We observe a correlation between the total energy emitted during SFXT outbursts and the time interval covered by the outbursts (defined as the ...

  16. The Reddening of Red Supergiants: When Smoke Gets In Your Eyes

    CERN Document Server

    Massey, P; Levesque, E M; Olsen, K A G; Clayton, G; Josselin, E; Massey, Philip; Plez, Bertrand; Levesque, Emily M.; Clayton, Geoffrey; Josselin, Eric

    2005-01-01

    Deriving the physical properties of red supergiants (RSGs) depends upon accurate corrections for reddening by dust. We use our recent modeling of the optical spectra of RSGs to address this topic. We find: (1) Previous broad-band studies have underestimated the correction for extinction in the visible, and hence the luminousities, if derived from V. (2) A significant fraction of RSGs in Galactic OB associations and clusters show up to several magnitudes of excess visual extinction compared to OB stars in the same regions; we argue that this is likely due to circumstellar dust around the RSGs. (3) RSGs contribute dust grains at the rate of $3 \\times 10^{-8} M_\\odot$ yr$^{-1}$ kpc$^{-2}$ in the solar neighborhood, comparable to what we estimate for late-type WC Wolf-Rayet stars, $1 \\times 10^{-7} M_\\odot$ yr$^{-1}$ kpc$^{-2}$. In the solar neighborhood this represents only a few percent of the dust production (which is dominated by low-mass AGBs), but we note that in low-metallicity starbursts, dust production ...

  17. Three-micron spectra of AGB stars and supergiants in nearby galaxies

    CERN Document Server

    Matsuura, M; Van Loon, J T; Yamamura, I; Markwick, A J; Whitelock, P A; Woods, P M; Marshall, J R; Feast, M W; Waters, L B F M

    2005-01-01

    The dependence of stellar molecular bands on the metallicity is studied using infrared L-band spectra of AGB stars (both carbon-rich and oxygen-rich) and M-type supergiants in the Large and Small Magellanic Clouds (LMC and SMC) and in the Sagittarius Dwarf Spheroidal Galaxy. The spectra cover SiO bands for oxygen-rich stars, and acetylene (C2H2), CH and HCN bands for carbon-rich AGB stars. The equivalent width of acetylene is found to be high even at low metallicity. The high C2H2 abundance can be explained with a high carbon-to-oxygen (C/O) ratio for lower metallicity carbon stars. In contrast, the HCN equivalent width is low: fewer than half of the extra-galactic carbon stars show the 3.5micron HCN band, and only a few LMC stars show high HCN equivalent width. HCN abundances are limited by both nitrogen and carbon elemental abundances. The amount of synthesized nitrogen depends on the initial mass, and stars with high luminosity (i.e. high initial mass) could have a high HCN abundance. CH bands are found in...

  18. Chemistry and Kinematics of Red Supergiant Stars in the Young Massive Cluster NGC 2100

    CERN Document Server

    Patrick, L R; Davies, B; Kudritzki, R-P; Hénault-Brunet, V; Bastian, N; Lapenna, E; Bergemann, M

    2016-01-01

    We have obtained K-band Multi-Object Spectrograph (KMOS) near-IR spectroscopy for 14 red supergiant stars (RSGs) in the young massive star cluster NGC 2100 in the Large Magellanic Cloud (LMC). Stellar parameters including metallicity are estimated using the J-band analysis technique, which has been rigorously tested in the Local Universe. We find an average metallicity for NGC 2100 of [Z]=$-$0.38$\\pm$0.20 dex, in good agreement with estimates from the literature for the LMC. Comparing our results in NGC 2100 with those for a Galactic cluster (at Solar-like metallicity) with a similar mass and age we find no significant difference in the location of RSGs in the Hertzsprung--Russell diagram. We combine the observed KMOS spectra to form a simulated integrated-light cluster spectrum and show that, by analysing this spectrum as a single RSG, the results are consistent with the average properties of the cluster. Radial velocities are estimated for the targets and the dynamical properties are estimated for the first...

  19. THE PERIOD-LUMINOSITY RELATION OF RED SUPERGIANT STARS IN THE SMALL MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    The characteristics of light variation of red supergiant (RSG) stars in the Small Magellanic Cloud (SMC) are analyzed based on the nearly 8-10 year data collected by the ASAS and MACHO projects. The 126 identified RSGs are classified into five categories accordingly: 20 with poor photometry, 55 with no reliable period, 6 with semi-regular variation, 15 with a long secondary period (LSP) and distinguishable short period, and 30 with only an LSP. For the semi-regular variables and the LSP variables with distinguishable short period, the KS -band period-luminosity (P-L) relation is analyzed and compared with that of the Galaxy, the Large Magellanic Cloud, and M33. It is found that the RSGs in these galaxies obey a similar P-L relation except for those in the Galaxy. In addition, the P-L relations in the infrared bands, namely, the 2MASS JHKS , Spitzer/IRAC, and Spitzer/MIPS 24 μm bands, are derived with high reliability. The best P-L relation occurs in the Spitzer/IRAC [3.6] and [4.5] bands. Based on the comparison with the theoretical calculation of the P-L relation, the mode of pulsation of RSGs in the SMC is suggested to be the first-overtone radial mode.

  20. Complexes of triggered star formation in supergiant shell of Holmberg II.

    Science.gov (United States)

    Egorov, Oleg V.; Lozinskaya, Tatiana A.; Moiseev, Alexei V.; Shchekinov, Yuri A.

    2016-09-01

    We report a detailed analysis of all regions of current star formation in the walls of the supergiant H I shell (SGS) in the galaxy Holmberg II based on observations with a scanning Fabry-Perot interferometer at the 6-m SAO RAS telescope. We compare the structure and kinematics of ionized gas with that of atomic hydrogen and with the stellar population of the SGS. Our deep Hα images and archival images taken by the HST demonstrate that current star formation episodes are larger and more complicated than previously thought: they represent unified star-forming complexes with sizes of several hundred pc rather than `chains' of separate bright nebulae in the walls of the SGS. The fact that we are dealing with unified complexes is evidenced by identified faint shell-like structures of ionized and neutral gas which connect several distinct bright H II regions. Formation of such complexes is due to the feedback of stars with very inhomogeneous ambient gas in the walls of the SGS. The arguments supporting an idea about the triggering of star formation in SGS by the H I supershells collision are presented. We also found a faint ionized supershell inside the H I SGS expanding with a velocity of no greater than 10 - 15 km s-1. Five OB stars located inside the inner supershell are sufficient to account for its radiation, although a possibility of leakage of ionizing photons from bright H II regions is not ruled out as well.

  1. Pulsations of red supergiant pair-instability supernova progenitors leading to extreme mass loss

    CERN Document Server

    Moriya, Takashi J

    2014-01-01

    Recent stellar evolution models show consistently that very massive metal-free stars evolve into red supergiants shortly before they explode. We argue that the envelopes of these stars, which will form pair-instability supernovae, become pulsationally unstable, and that this will lead to extreme mass-loss rates even though the metal content of the envelopes is very small. We investigate the pulsational properties of such models, and derive pulsationally induced mass-loss rates which take the damping effects of the mass loss on the pulsations selfconsistently into account. We find that the pulsations may induce mass-loss rates of ~ 1e-4 - 1e-2 Msun/yr shortly before the explosions, which may create a dense circumstellar medium. Our results show that very massive stars with dense circumstellar media may originate from a wider initial mass range than that of pulsational-pair instability supernovae. The extreme mass loss will cease when so much of the hydrogen-rich envelope is lost that the star becomes more comp...

  2. Cumulative luminosity distributions of Supergiant Fast X-ray Transients in hard X-rays

    CERN Document Server

    Paizis, A

    2014-01-01

    We have analyzed in a systematic way about nine years of INTEGRAL data (17-100 keV) focusing on Supergiant Fast X-ray Transients (SFXTs) and three classical High Mass X-ray Binaries (HMXBs). Our approach has been twofold: image based analysis, sampled over a ~ks time frame to investigate the long-term properties of the sources, and lightcurve based analysis, sampled over a 100s time frame to seize the fast variability of each source during its ~ks activity. We find that while the prototypical SFXTs (IGR J17544-2619, XTE J1739-302 and SAX J1818.6-1703) are among the sources with the lowest ~ks based duty cycle ($<$1% activity over nine years of data), when studied at the 100s level, they are the ones with the highest detection percentage, meaning that, when active, they tend to have many bright short-term flares with respect to the other SFXTs. To investigate in a coherent and self consistent way all the available results within a physical scenario, we have extracted cumulative luminosity distributions for ...

  3. Complexes of triggered star formation in supergiant shell of Holmberg II

    CERN Document Server

    Egorov, Oleg V; Moiseev, Alexei V; Shchekinov, Yuri A

    2016-01-01

    We report a detailed analysis of all regions of current star formation in the walls of the supergiant HI shell (SGS) in the galaxy Holmberg II based on observations with a scanning Fabry-Perot interferometer at the 6-m SAO RAS telescope. We compare the structure and kinematics of ionized gas with that of atomic hydrogen and with the stellar population of the SGS. Our deep H$\\alpha$ images and archival images taken by the HST demonstrate that current star formation episodes are larger and more complicated than previously thought: they represent unified star-forming complexes with sizes of several hundred pc rather than 'chains' of separate bright nebulae in the walls of the SGS. The fact that we are dealing with unified complexes is evidenced by identified faint shell-like structures of ionized and neutral gas which connect several distinct bright HII regions. Formation of such complexes is due to the feedback of stars with very inhomogeneous ambient gas in the walls of the SGS. The arguments supporting an ide...

  4. Quantitative Spectroscopic J-band Study of Red Supergiants in Perseus OB-1

    CERN Document Server

    Gazak, J Zachary; Kudritzki, Rolf; Bergemann, Maria; Plez, Bertrand

    2014-01-01

    We demonstrate how the metallicities of red supergiant (RSG) stars can be measured from quantitative spectroscopy down to resolutions of ~3000 in the J-band. We have obtained high resolution spectra on a sample of the RSG population of h and chi Persei, a double cluster in the solar neighborhood. We show that careful application of the MARCS model atmospheres returns measurements of Z consistent with solar metallicity. Using two grids of synthetic spectra--one in pure LTE and one with NLTE calculations for the most important diagnostic lines--we measure Z = +0.04 +/- 0.10 (LTE) and Z = -0.04 +/- 0.08 (NLTE) for the sample of eleven RSGs in the cluster. We degrade the spectral resolution of our observations and find that those values remain consistent down to resolutions of less than R of 3000. Using measurements of effective temperatures we compare our results with stellar evolution theory and find good agreement. We construct a synthetic cluster spectrum and find that analyzing this composite spectrum with s...

  5. The potential of Red Supergiants as extra-galactic abundance probes at low spectral resolution

    CERN Document Server

    Davies, Ben; Figer, Donald F

    2010-01-01

    Red Supergiants (RSGs) are among the brightest stars in the local universe, making them ideal candidates with which to probe the properties of their host galaxies. However, current quantitative spectroscopic techniques require spectral resolutions of R>17,000, making observations of RSGs at distances greater than 1Mpc unfeasible. Here we explore the potential of quantitative spectroscopic techniques at much lower resolutions, R ~2-3000. We take archival J-band spectra of a sample of RSGs in the Solar neighbourhood. In this spectral region the metallic lines of FeI, MgI, SiI and TiI are prominent, while the molecular absorption features of OH, H_2O, CN and CO are weak. We compare these data with synthetic spectra produced from the existing grid of model atmospheres from the MARCS project, with the aim of deriving chemical abundances. We find that all stars studied can be unambiguously fit by the models, and model parameters of log g, effective temperatures Teff, microturbulence and global metal content may be ...

  6. Large Magellanic Cloud helium-rich peculiar blue supergiants and SN 1987A

    International Nuclear Information System (INIS)

    The theoretical distribution of massive stars in the H-R diagram is compared to the revised data of Fitzpatrick and Garmany for the LMC. Preferred models of about 20 M solar masses undergo a thermal contraction at T(eff) about 35,000 K at the end of core hydrogen burning but reestablish thermal equilibrium to the red of the main sequence at T(eff) about 20,000 K after ignition of a hydrogen-burning shell. They then evolve on a nuclear time scale to T(eff) about 6000 K where they lose thermal equilibrium and jump to the Hayashi track. The theoretical and observed distributions agree with two significant exceptions: the blue thermal contraction gap is overpopulated compared to the theory, and there is a ledge crossing the center of the H-R diagram. The hypothesis that some of the observed stars in the blue gap are secondaries that have accreted helium-rich matter from deep within the hydrogen envelope of a red supergiant primary is explored. Some preliminary observational justification is given. 27 refs

  7. THE ULTRA-LONG GAMMA-RAY BURST 111209A: THE COLLAPSE OF A BLUE SUPERGIANT?

    Energy Technology Data Exchange (ETDEWEB)

    Gendre, B.; Cutini, S.; D' Elia, V. [ASI Science Data Center, via Galileo Galilei, I-00044 Frascati (Italy); Stratta, G. [Osservatorio Astronomico di Roma, OAR-INAF, via Frascati 33, I-00040, Monte Porzio Catone (Italy); Atteia, J. L.; Klotz, A. [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Basa, S. [Aix Marseille Universite, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); Boeer, M. [CNRS, ARTEMIS, UMR 7250, Boulevard de l' Observatoire, BP 4229, F-06304 Nice Cedex 4 (France); Coward, D. M.; Howell, E. J [University of Western Australia, School of Physics, University of Western Australia, Crawley WA 6009 (Australia); Piro, L., E-mail: bruce.gendre@gmail.com [Istituto di Astrofisica e Planetologia Spaziali di Roma, INAF, via fosso del cavaliere 100, I-00133 Roma (Italy)

    2013-03-20

    We present optical, X-ray and gamma-ray observations of GRB 111209A, observed at a redshift of z = 0.677. We show that this event was active in its prompt phase for about 25000 s, making it the longest burst ever observed. This rare event could have been detected up to z {approx} 1.4 in gamma-rays. Compared to other long gamma-ray bursts (GRBs), GRB 111209A is a clear outlier in the energy-fluence and duration plane. The high-energy prompt emission shows no sign of a strong blackbody component, the signature of a tidal disruption event, or a supernova shock breakout. Given the extreme longevity of this event, and lack of any significant observed supernova signature, we propose that GRB 111209A resulted from the core-collapse of a low-metallicity blue supergiant star. This scenario is favored because of the necessity to supply enough mass to the central engine over a duration of thousands of seconds. Hence, we suggest that GRB 111209A could have more in common with population III stellar explosions, rather than those associated with normal long GRBs.

  8. The Chromospheric Structure and Wind of the K-Supergiant Lambda Velorum

    Science.gov (United States)

    Carpenter, Kenneth G.; Ayres, T. R.; Brown, A.; Harper, G. M.; Wahlgren, G. M.

    2011-01-01

    Recently, the 1326-1466 Å region of the FUV spectrum of the K4 Ib-II supergiant Lambda Vel was observed with the Cosmic Origins Spectrograph (COS) on HST, as part of the Ayres and Redfield Cycle 17 SNAP program "SNAPing Coronal Iron.” This spectrum covers a region not previously recorded in Lambda Vel at high resolution and, in a mere 20 minutes of exposure, reveals an amazing treasure trove of information. It shows a wide variety of strong atomic and molecular emission lines formed in the chromosphere and multiple atomic absorption lines formed in the stellar wind, both superposed on a bright chromospheric continuum. Further evidence of the stellar wind is seen in the P Cygni profiles presented by the C II (UV 1) lines near 1335 Å. We combine this COS data with archival GHRS spectra of other selected FUV and NUV regions to better characterize the outer atmospheric structure of the star and its massive, outflowing wind.

  9. Discovery of an Extraordinary Number of Red Supergiants in the Inner Galaxy

    Science.gov (United States)

    Messineo, Maria; Zhu, Qingfeng; Menten, Karl M.; Ivanov, Valentin D.; Figer, Donald F.; Kudritzki, Rolf-Peter; Chen, C.-H. Rosie

    2016-05-01

    In this Letter, we present a search for Galactic red supergiant stars (RSGs) in the direction of the inner Galaxy. A total of 94 targets selected from the 2MASS and GLIMPSE I North catalogs—via their blue extinction-free Q1 and Q2 colors—were spectroscopically observed at infrared wavelengths (in the H- and K-bands at R ˜ 1000), and an extraordinary high detection rate of RSGs (\\gt 61%) was found. We identified spectroscopically 58 RSGs, based on their flat continua and large equivalent widths of the CO-band at 2.293 μm (EW > 45 Å). This increase corresponds to about 25% of previously known RSGs in the Galactic region 10° < l < 60°, -1.°1 < b < 1.°1. In order to confirm the location of the new RSGs in the inner Galaxy, distances were estimated for a subsample of 47 stars with the clump method and found to range from 3.6 ± 0.4 to 8.6 ± 0.7 kpc. The large new sample will allow us to investigate Galactic metallicity gradients as a function of galactocentric distances and azimuthal angles. Such information is currently an highly disputed issue to constrain models of Galaxy formation and evolution.

  10. SN 2004A: Another Type II-P Supernova with a Red Supergiant Progenitor

    CERN Document Server

    Hendry, M A; Cenko, S B; Crockett, R M; Fox, D W; Gal-Yam, A; Kudritzki, R P; Maund, J R; Moon, D S; Smartt, S J

    2006-01-01

    We present a monitoring study of SN 2004A and probable discovery of a progenitor star in pre-explosion HST images. The photometric and spectroscopic monitoring of SN 2004A show that it was a normal Type II-P which was discovered in NGC 6207 about two weeks after explosion. We compare SN 2004A to the similar Type II-P SN 1999em and estimate an explosion epoch of 2004 January 6. We also calculate three new distances to NGC 6207 of 21.0 +/-4.3, 21.4 +/-3.5 and 25.1 +/-1.7Mpc. The former was calculated using the Standard Candle Method (SCM) for SNe II-P, and the latter two from the Brightest Supergiants Method (BSM). We combine these three distances with existing kinematic distances, to derive a mean value of 20.3 +/-3.4Mpc. Using this distance we estimate that the ejected nickel mass in the explosion is 0.046(+0.031,-0.017) Msolar. The progenitor of SN 2004A is identified in pre-explosion WFPC2 F814W images with a magnitude of mF814W = 24.3 +/-0.3, but is below the detection limit of the F606W images. We show th...

  11. The first spectropolarimetric monitoring of the peculiar O4Ief supergiant zeta Puppis

    CERN Document Server

    Hubrig, S; Ilyin, I; Schöller, M; Oskinova, L M

    2016-01-01

    The origin of the magnetic field in massive O-type stars is still under debate. To model the physical processes responsible for the generation of O star magnetic fields, it is important to understand whether correlations between the presence of a magnetic field and stellar evolutionary state, rotation velocity, kinematical status, and surface composition can be identified. The O4Ief supergiant zeta Pup is a fast rotator and a runaway star, which may be a product of a past binary interaction, possibly having had an encounter with the cluster Trumper 10 some 2Myr ago. The currently available observational material suggests that certain observed phenomena in this star may be related to the presence of a magnetic field. We acquired spectropolarimetric observations of zeta Pup with FORS2 mounted on the 8-m Antu telescope of the VLT to investigate if a magnetic field is indeed present in this star. We show that many spectral lines are highly variable and probably vary with the recently detected period of 1.78d. No ...

  12. SPITZER, VERY LARGE TELESCOPE, AND VERY LARGE ARRAY OBSERVATIONS OF THE GALACTIC LUMINOUS BLUE VARIABLE CANDIDATE HD 168625

    International Nuclear Information System (INIS)

    We present mid-IR and radio observations of the Galactic luminous blue variables (LBVs) candidate HD 168625 and its associated nebula. We obtained mid-IR spectroscopic observations using the Infrared Spectrograph on board the Spitzer Space Telescope, and performed mid-IR and radio imaging observations using VISIR on the Very Large Telescope and the Very Large Array with comparable angular resolution. Our spectroscopic observations detected spectral features attributable to polycyclic aromatic hydrocarbons (PAHs) and therefore indicate the presence of a photodissociation region (PDR) around the ionized nebula. This result increases the number of LBVs and LBV candidates where a PDR has been found, confirming the importance of such a component in the total mass-loss budget of the central object during this elusive phase of massive star evolution. We have analyzed and compared the mid-IR and radio maps, and derive several results concerning the associated nebula. There is evidence for grain distribution variations across the nebula, with a predominant contribution from bigger grains in the northern part of the nebula while PAH and smaller grains are more concentrated in the southern part. A compact radio component located where there is a lack of thermal dust grains corroborates the presence of a shock in the southern nebula, which could arise as a consequence of the interaction of a fast outflow with the slower, expanding dusty nebula. Such a shock would be a viable means for PAH production as well as for changes in the grain size distribution. Finally, from the detection of a central radio component probably associated with the wind from the central massive supergiant, we derive a current mass-loss rate of M-dot =(1.46±0.15)x10-6 Msun yr-1.

  13. Latitudinal variation of thermospheric hydrogen near solstice from AE-D observations

    Science.gov (United States)

    Sanatani, S.; Breig, E. L.

    1988-01-01

    Variations of thermospheric neutral atomic hydrogen with latitude during a solstice season near solar minimum were investigated using data acquired with the polar-orbiting AE-D satellite. Hydrogen concentrations at low latitude were found to be comparable to those found from observations with the AE-E satellite, but were slightly higher than concentrations derived from the 1983 mass spectrometer incoherent scatter atmospheric model. Results confirm the general summer-to-winter density increase, large latitudinal gradients in the summer hemisphere, and the winter enhancement of hydrogen observed in AE-C nighttime measurements. The AE-D data, however, show a small polar depression in hydrogen concentration at high winter latitudes, attributed to atmospheric dynamics following auroral heating. The density gradients observed by AE-D in the summer hemisphere were in sharp contrast to the more constant horizontal daytime profiles reported from OGO-6 and previous AE-C measurements, indicating the possibility of local time effects.

  14. Implementation of AES as a Custom Hardware using NIOS II Processor

    Directory of Open Access Journals (Sweden)

    Meghana Hasamnis

    2012-08-01

    Full Text Available In this paper Advanced Encryption Standard (AES algorithm has been designed and implemented as custom hardware. The algorithm is controlled through C-code written in NIOS II IDE. AES as a custom hardware is interfaced with the system designed around NIOS II Processor using SOPC builder tool. AES is written in hardware in VHDL language and the interface is through GPIO (General Purpose Input / Output Port. AES implemented using data size of 128 bits, while the length of the key used is of 128 bits. The key size of AES used is of 128 bits, as it is secure from the different attacks in existence. The FPGA used is CYCLONE II from Altera. AES as a custom hardware increases the speed of encryption and serves as an accelerator and hence improves the performance of the system.

  15. The evidence for clumpy accretion in the Herbig Ae star HR 5999

    Science.gov (United States)

    Perez, M. R.; Grady, C. A.; The, P. S.

    1994-01-01

    Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 has revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 A) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Ly(alpha), O I and C IV emission lines, which are correlated with the UV excess luminosity. We also observe variability in the spectral type inferred from the UV spectral energy distribution, ranging from A5 IV-III in high state to A7 III in the low state. The trend of earlier inferred spectral type with decreasing wavelength and with increasing UV continuum flux has previously been noted as a signature of accretion disks in lower mass pre-main sequence stars (PMS) and in systems undergoing FU Orionis-type outbursts. Our data represent the first detection of similar phenomena in an intermediate mass (M equal to or greater than 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as +300 km/s, much as is seen toward beta Pic, and suggest that we also view this system through the debris disk. The absence of UV lines with the rotational broadening expected given the optical data (A7 IV, upsilon sin i = 180 plus or minus 20 km/s) for this system also suggests that most of the UV light originates in the disk, even in the low continuum state. The dramatic variability in the column density of accreting gas, consistent with clumpy accretion, such as has been observed toward beta Pic, is a hallmark of accretion onto young stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed.

  16. The onset of cluster formation around Herbig Ae/Be stars

    OpenAIRE

    Testi, L.; Palla, F.; Natta, A.

    1998-01-01

    The large body of near infrared observations presented in Testi et al. (1997; 1998) are analysed with the aim of characterizing the young stellar clusters surrounding Herbig Ae/Be stars. The results confirm the tendency of early Be stars to be surrounded by dense clusters of lower mass "companions", while Ae stars are never found to be associated with conspicuous groups. The transition between the different environments appears to occur smoothly from Ae to Be stars without a sharp threshold. ...

  17. The use of the inner zone electron model AE-5 and associated computer programs

    Science.gov (United States)

    Teague, M. J.; Vette, J. I.

    1972-01-01

    A users guide to the inner radiation zone electron model AE-5 is introduced. The guide covers a description of the model, the forms in which it is available, directions on how to use the model, and a discussion of its limitations. Computer programs MODEL and ORP are described. These are major programs needed to use the electron models AE-4 and AE-5 and the smoothed proton models.

  18. Role of AE2 for pHi regulation in biliary epithelial cells

    Directory of Open Access Journals (Sweden)

    Axel R. Concepcion

    2014-01-01

    Full Text Available The Cl-/HCO3- anion exchanger 2 (AE2 is known to be involved in intracellular pH (pHi regulation and transepithelial acid-base transport. Early studies showed that AE2 gene expression is reduced in liver biopsies and blood mononuclear cells from patients with primary biliary cirrhosis (PBC, a disease characterized by chronic nonsuppurative cholangitis associated with antimitochondrial antibodies (AMA and other autoimmune phenomena. Microfluorimetric analysis of the Cl-/HCO3- anion exchange (AE in isolated cholangiocytes showed that the cAMP-stimulated AE activity is diminished in PBC compared to both healthy and diseased controls. More recently, it was found that miR-506 is upregulated in cholangiocytes of PBC patients and that AE2 may be a target of miR-506. Additional evidence for a pathogenic role of AE2 dysregulation in PBC was obtained with Ae2a,b-/- mice, which develop biochemical, histological, and immunologic alterations that resemble PBC (including development of serum AMA. Analysis of HCO3- transport systems and pHi regulation in cholangiocytes from normal and Ae2a,b-/- mice confirmed that AE2 is the transporter responsible for the Cl–/HCO3– exchange in these cells. On the other hand, both Ae2a,b+/+ and Ae2a,b-/- mouse cholangiocytes exhibited a Cl--independent bicarbonate transport system, essentially a Na+-bicarbonate cotransport (NBC system, which could contribute to pHi regulation in the absence of AE2.

  19. A Lossless Data Hiding Technique based on AES-DWT

    Directory of Open Access Journals (Sweden)

    Gustavo Fernandaacute;ndez Torres2

    2012-09-01

    Full Text Available In this paper we propose a new data hiding technique. The new technique uses steganography and cryptography on images with a size of 256x256 pixels and an 8-bit grayscale format. There are design restrictions such as a fixed-size cover image, and reconstruction without error of the hidden image. The steganography technique uses a Haar-DWT (Discrete Wavelet Transform with hard thresholding and LSB (Less Significant Bit technique on the cover image. The algorithms used for compressing and ciphering the secret image are lossless JPG and AES, respectively. The proposed technique is used to generate a stego image which provides a double type of security that is robust against attacks. Results are reported for different thresholds levels in terms of PSNR.

  20. Quality of Life in Prodromal HD: Qualitative Analyses of Discourse from Participants and Companions

    Directory of Open Access Journals (Sweden)

    Rebecca E. Ready

    2011-01-01

    Full Text Available Persons who are at risk for Huntington's Disease (HD can be tested for the HD gene expansion before symptom onset. People with the gene expansion, but no clinical diagnosis, are in the prodromal phase of HD. This study explored quality of life (QOL in prodromal HD. Interviews about QOL, conducted with 9 prodromal HD participants and 6 companions, were transcribed. Discourse was coded for emotional valence, content (e.g., coping, spirituality, interpersonal relationships, HD in others, and employment, and time frame (e.g., current, past, and future. Respondents were more positive than negative about the present, which was their major focus. The most common statements were about positive attitudes. Positive statements were made about spirituality, and negative statements were made about HD in other people. Relationships, employment, and coping with HD reflected both positivity and negativity. Participants and companions spoke of the future with different concerns. Applicability of findings to the clinical management of HD are discussed.

  1. High spectral resolution spectroscopy of the SiO fundamental lines in red giants and red supergiants with VLT/VISIR

    CERN Document Server

    Ohnaka, Keiichi

    2013-01-01

    We present high spectral resolution (R = 30000) spectroscopic observations of the SiO fundamental lines near 8.1 micron in 16 bright red giants and red supergiants using VLT/VISIR. Our sample consists of seven normal K--M giants, three Mira stars, three optically bright red supergiants, two dusty red supergiants, and the enigmatic object GCIRS3 near the Galactic center. We detected SiO fundamental lines in all of our program stars except for GCIRS3. The SiO lines in normal K and M giants as well as optically bright red supergiants do not show P-Cyg profiles or blueshifts, which means the absence of systematic outflows in the SiO line forming region. On the other hand, we detected P-Cyg profiles in the SiO lines in the dusty red supergiants VY CMa and VX Sgr (with the latter being a new detection), which suggest outflow velocities of 27 and 17 km/s, respectively. We derived basic stellar parameters (effective temperature, surface gravity, luminosity, and mass) for the normal K--M giants and optically bright re...

  2. Comportamento de Aedes albopictus e de Ae. scapularis adultos (Diptera: Culicidae no Sudeste do Brasil Adults Aedes albopictus and Ae. scapularis behavior (Diptera: Culidae in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Oswaldo Paulo Forattini

    2000-10-01

    Full Text Available OBJETIVO: Observar e comparar o comportamento das espécies de Aedes albopictus e de Ae. scapularis, na localidade de Pedrinhas, litoral sul do Estado de São Paulo, Brasil. MÉTODOS: As observações foram feitas de outubro de 1996 a janeiro de 2000. Foram realizadas coletas sistemáticas de formas adultas mediante a utilização de isca humana, aspirações ambientais e armadilha tipo Shannon. A domiciliação foi estimada pelo índice de Nuorteva e pela razão de sinantropia. RESULTADOS: Foram feitas 87 coletas diurnas, com a obtenção de 872 adultos fêmeas. As médias de Williams', multiplicadas por 100, foram de 118 e 21 para Ae. albopictus nos horários de 7h às 18h e de 18h às 20h, respectivamente. Quanto a Ae. scapularis, foram de 100 e 106 nos mesmos períodos. Esse último revelou pico de atividade crepuscular vespertina. Na aspiração de abrigos, obteve-se o total de 1.124 espécimens, dos quais 226 Ae. albopictus e 898 Ae. scapularis. O período de janeiro a maio correspondeu ao de maior rendimento para ambos os mosquitos. Quanto à armadilha de Shannon, as coletas realizadas na mata revelaram a ausência de Ae. albopictus. No que concerne à domiciliação, esse último mostrou os maiores valores de índices, enquanto Ae. scapularis revelou comportamento de tipo ubiquista. CONCLUSÕES: Os resultados confirmam outras observações, permitindo levantar hipóteses. Em relação a Ae. scapularis, sugere-se que possa existir fenômeno de diapausa das fêmeas no período verão-outono, a qual cessaria no inverno-primavera quando então a atividade seria retomada. Quanto a Ae. albopictus, os dados sugerem que se trata de população em processo adaptativo ao novo ambiente.OBJECTIVE: Aedes albopictus and Ae. scapularis were found living together in the Pedrinhas Village, Southeastern of São Paulo State, Brazil. This finding was a good opportunity to make observations about the mosquitoes' behavior. METHODS: From October 1996 to

  3. Analysis of Fracture Signals from Tooth/Composite Restoration According to AE Sensor Attachment

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Ja Uk; Choi, Nak Sam [Hanyang University, Ansan (Korea, Republic of)

    2011-10-15

    Acoustic emission(AE) signals during the polymerization shrinkage of composite resin subjected to the LED light exposure were detected through a wave guide method and a direct sensor attachment method. For PMMA, human tooth, stainless steel substrate, data of AE hits and amplitudes were compared. For the test using the wave guide, AE amplitudes decreased because of the attenuant wave. However, AE hits and 1st peak frequency distribution were not different according to the sensor attachments. Through the experiments, wave guide could be used for a nondestructive evaluation of the marginal disintegrative fracture of dental restoration.

  4. About the extrasolar multi-planet system around HD160691

    CERN Document Server

    Gozdziewski, K; Migaszewski, C; Gozdziewski, Krzysztof; Maciejewski, Andrzej J.; Migaszewski, Cezary

    2006-01-01

    We re-analyze the precision radial velocity (RV) observations of HD160691 (mu Ara) by the Anglo-Australian Planet Search Team. The star is supposed to host two Jovian companions (HD160691b, HD160691c) in long-period orbits (about 630 days and 2500 days, respectively) and a hot-Neptune (HD160691d) in about 9 days orbit. We perform a global search for the best fits in the orbital parameters space with a hybrid code employing the genetic algorithm and simplex method. The stability of Keplerian fits is verified with the N-body model of the RV signal that takes into account the dynamical constraints (so called GAMP method). Our analysis reveals a signature of the fourth, yet unknown and unconfirmed, 0.5 Jupiter-mass planet in about 307 days orbit. In overview, the global architecture of the four-planet configuration recalls the Solar system. All companions of HD160691 move in close to circular orbits. The orbits of the two inner Jovian planets are close to the 2:1 mean motion resonance (MMR). The alternative three...

  5. Asteroseismology of the $\\delta$ Scuti star HD 50844

    CERN Document Server

    Chen, X H; Lai, X J; Wu, T

    2016-01-01

    Aims. We aim to probe the internal structure and investigate more detailed information of the $\\delta$ Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the $\\delta$ Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree $l$ and azimuthal number $m$ are unique. The corresponding rotational period of HD 50844 is found to be 2.44$^{+0.13}_{-0.08}$ days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as...

  6. Cummins MD & HD Accessory Hybridization CRADA -Annual Report FY15

    Energy Technology Data Exchange (ETDEWEB)

    Deter, Dean D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    There are many areas of MD and HD vehicles that can be improved by new technologies and optimized control strategies. Component optimization and idle reduction need to be addressed, this is best done by a two part approach that includes selecting the best component technology, and/or architecture, and optimized controls that are vehicle focused. While this is a common focus in the light duty industry it has been gaining momentum in the MD and HD market as the market gets more competitive and the regulations become more stringent. When looking into systems optimization and idle reduction technologies, affected vehicle systems must first be considered, and if possible included in the new architecture to get the most benefit out of these new capabilities. Typically, when looking into idle reduction or component optimization for MD/HD, the vehicle s accessories become a prime candidate for electrification or hybridization. While this has already been studied on light duty vehicles (especially on hybrids and electric vehicles) it has not made any head way or market penetration in most MD and HD applications. If hybrids and electric MD and HD vehicles begin to break into the market this would be a necessary step into the ability to make those vehicles successful by allowing for independent, optimized operation separate from the engine.

  7. Superlattice origin of incommensurable density waves in $La__{2-x}Ae_xCuO4$ (Ae = Ba, Sr)

    CERN Document Server

    Bucher, Manfred

    2013-01-01

    In line with the Coulomb-oscillator model of superconductivity, loop currents of excited 3s electrons from O^2- ions, passing in the CuO2 plane through nuclei of nearest-neighbor oxygen quartets, create the antiferromagnetic phase of undoped copper oxides. Holes, introduced by alkaline-earth doping of La2CuO4, destroy the loop currents, thereby weakening antiferromagnetism until it disappears at doping x = 0.02. Further doping of La_2-xAe_xCuO4 gives rise to incommensurate free-hole density waves whose wavelength is determined by the spacing of a doping superlattice. Modulating the ordering of the ions' magnetic moments, the charge-density wave, of incommensurability 2 delta, causes a magnetic density wave of incommensurability delta. The formula derived for delta(x) is in excellent agreement with data from X-ray diffraction and neutron scattering.

  8. Spontaneous wheat-Aegilops biuncialis, Ae. geniculata and Ae. triuncialis amphiploid production, a potential way of gene transference

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, I.; Escorial, C.; Garcia-Baudin, J. M.; Chueca, M. C.

    2009-07-01

    Some F1 hybrid plants between three species of the Aegilops genus and different hexaploid wheat Triticum aestivum cultivars show certain self-fertility, with averages of F{sub 1} hybrids bearing F{sub 2} seeds of 8.17%, 5.12% and 48.14% for Aegilops biuncialis, Aegilops geniculata and Aegilops triuncialis respectively. In the Ae. triuncialis-wheat combination with Astral wheat cultivar, the fertility was higher than that found in the other combinations. All the F2 seeds studied were spontaneous amphiploids (2n=10x=70). The present study evidences the possibility of spontaneous formation of amphiploids between these three Aegilops species and hexaploid wheat and discusses their relevance for gene transference. Future risk assessment of transgenic wheat cultivars needs to evaluate the importance of amphiploids as a bridge for transgene introgression and for gene escape to the wild. (Author)

  9. The HD+ dissociative recombination rate coefficient at low temperature

    Directory of Open Access Journals (Sweden)

    Wolf A.

    2015-01-01

    Full Text Available The effect of the rotational temperature of the ions is considered for low-energy dissociative recombination (DR of HD+. Merged beams measurements with HD+ ions of a rotational temperature near 300 K are compared to multichannel quantum defect theory calculations. The thermal DR rate coefficient for a Maxwellian electron velocity distribution is derived from the merged-beams data and compared to theoretical results for a range of rotational temperatures. Good agreement is found for the theory with 300 K rotational temperature. For a low-temperature plasma environment where also the rotational temperature assumes 10 K, theory predicts a considerably higher thermal DR rate coefficient. The origin of this is traced to predicted resonant structures of the collision-energy dependent DR cross section at few-meV collision energies for the particular case of HD+ ions in the rotational ground state.

  10. Stability and Formation of the Resonant System HD 73526

    CERN Document Server

    Sándor, Z; Klagyivik, P

    2007-01-01

    Based on radial velocity measurements it has been found recently that the two giant planets detected around the star HD 73526 are in 2:1 resonance. However, as our numerical integration shows, the derived orbital data for this system result in chaotic behavior of the giant planets, which is uncommon among the resonant extrasolar planetary systems. We intend to present regular (non-chaotic) orbital solutions for the giant planets in the system HD 73526 and offer formation scenarios based on combining planetary migration and sudden perturbative effects such as planet-planet scattering or rapid dispersal of the protoplanetary disk. A comparison with the already studied resonant system HD 128311, exhibiting similar behavior, is also done. The new sets of orbital solutions have been derived by the Systemic Console (www.oklo.org). The stability of these solutions has been investigated by the Relative Lyapunov indicator, while the migration and scattering effects are studied by gravitational N-body simulations apply...

  11. The Discovery of HD 37605c and a Dispositive Null Detection of Transits of HD 37605b

    DEFF Research Database (Denmark)

    Xuesong Wang, Sharon; Wright, Jason T.; Cochran, William;

    2012-01-01

    We report the radial-velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P~55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of ~7.5 years with a low eccentricity and an Msini of ~3.4 MJup. Our...... discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS) effort to provide precise ephemerides to long-period planets for transit follow......-up. With a total of 137 radial velocity observations covering almost eight years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using...

  12. Characterization of low-molecular-weight-glutenin subunit genes from the D-genome of Triticum aestivum, Aegilops crassa, Ae. cylindrica and Ae. tauschii

    NARCIS (Netherlands)

    Naghavi, M.R.; Ahmadi, S.; Shanejat-Boushehri, A.A.; Komaei, G.; Struik, P.C.

    2013-01-01

    Twenty low-molecular-weight-glutenin subunit (LMW-GS) gene sequences from the D-genome from Aegilops crassa (2n ¼ 4x ¼ 28), Ae. cylindrica (2n ¼ 4x ¼ 28), Ae. tauschii (2n ¼ 2x ¼ 14) and Triticum aestivum (2n ¼ 6x ¼ 42) were obtained using five sets of specific allele primer pairs. Only the sequence

  13. Chemistry and kinematics of red supergiant stars in the young massive cluster NGC 2100

    Science.gov (United States)

    Patrick, L. R.; Evans, C. J.; Davies, B.; Kudritzki, R.-P.; Hénault-Brunet, V.; Bastian, N.; Lapenna, E.; Bergemann, M.

    2016-06-01

    We have obtained K-band Multi-Object Spectrograph (KMOS) near-IR spectroscopy for 14 red supergiant stars (RSGs) in the young massive star cluster NGC 2100 in the Large Magellanic Cloud (LMC). Stellar parameters including metallicity are estimated using the J-band analysis technique, which has been rigorously tested in the Local Universe. We find an average metallicity for NGC 2100 of [Z] = -0.43 ± 0.10 dex, in good agreement with estimates from the literature for the LMC. Comparing our results in NGC 2100 with those for a Galactic cluster (at Solar-like metallicity) with a similar mass and age we find no significant difference in the location of RSGs in the Hertzsprung-Russell diagram. We combine the observed KMOS spectra to form a simulated integrated-light cluster spectrum and show that, by analysing this spectrum as a single RSG, the results are consistent with the average properties of the cluster. Radial velocities are measured for the targets and the dynamical properties are estimated for the first time within this cluster. The data are consistent with a flat velocity dispersion profile, and with an upper limit of 3.9 kms-1, at the 95 per cent confidence level, for the velocity dispersion of the cluster. However, the intrinsic velocity dispersion is unresolved and could, therefore, be significantly smaller than the upper limit reported here. An upper limit on the dynamical mass of the cluster is derived as Mdyn ≤ 15.2 × 104 M⊙ assuming virial equilibrium.

  14. Dense molecular clumps associated with the Large Magellanic Cloud supergiant shells LMC 4 and LMC 5

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Kosuke; Mizuno, Norikazu [Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033 (Japan); Minamidani, Tetsuhiro [Nobeyama Radio Observatory, 462-2 Nobeyama Minamimaki-mura, Minamisaku-gun, Nagano 384-1305 (Japan); Onishi, Toshikazu; Muraoka, Kazuyuki [Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, Osaka 599-8531 (Japan); Kawamura, Akiko; Muller, Erik; Tatematsu, Ken' ichi; Hasegawa, Tetsuo; Miura, Rie E.; Ezawa, Hajime [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Dawson, Joanne [Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); Tosaki, Tomoka [Joetsu University of Education, Yamayashiki-machi, Joetsu, Niigata 943-8512 (Japan); Sakai, Takeshi [Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Tsukagoshi, Takashi [College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512 (Japan); Tanaka, Kunihiko [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522 (Japan); Fukui, Yasuo, E-mail: kosuke.fujii@nao.ac.jp [Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

    2014-12-01

    We investigate the effects of supergiant shells (SGSs) and their interaction on dense molecular clumps by observing the Large Magellanic Cloud (LMC) star-forming regions N48 and N49, which are located between two SGSs, LMC 4 and LMC 5. {sup 12}CO (J = 3-2, 1-0) and {sup 13}CO(J = 1-0) observations with the ASTE and Mopra telescopes have been carried out toward these regions. A clumpy distribution of dense molecular clumps is revealed with 7 pc spatial resolution. Large velocity gradient analysis shows that the molecular hydrogen densities (n(H{sub 2})) of the clumps are distributed from low to high density (10{sup 3}-10{sup 5} cm{sup –3}) and their kinetic temperatures (T {sub kin}) are typically high (greater than 50 K). These clumps seem to be in the early stages of star formation, as also indicated from the distribution of Hα, young stellar object candidates, and IR emission. We found that the N48 region is located in the high column density H I envelope at the interface of the two SGSs and the star formation is relatively evolved, whereas the N49 region is associated with LMC 5 alone and the star formation is quiet. The clumps in the N48 region typically show high n(H{sub 2}) and T {sub kin}, which are as dense and warm as the clumps in LMC massive cluster-forming areas (30 Dor, N159). These results suggest that the large-scale structure of the SGSs, especially the interaction of two SGSs, works efficiently on the formation of dense molecular clumps and stars.

  15. DISCOVERY OF THE FIRST B[e] SUPERGIANTS IN M 31

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, M.; Oksala, M. E. [Astronomický ústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov (Czech Republic); Cidale, L. S.; Arias, M. L. [Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, B1900FWA La Plata (Argentina); Borges Fernandes, M., E-mail: kraus@sunstel.asu.cas.cz [Observatório Nacional, Rua General José Cristino 77, 20921-400 São Cristovão, Rio de Janeiro (Brazil)

    2014-01-01

    B[e] supergiants (B[e]SGs) are transitional objects in the post-main sequence evolution of massive stars. The small number of B[e]SGs known so far in the Galaxy and the Magellanic Clouds indicates that this evolutionary phase is short. Nevertheless, the strong aspherical mass loss occurring during this phase, which leads to the formation of rings or disk-like structures, and the similarity to possible progenitors of SN1987 A emphasize the importance of B[e]SGs for the dynamics of the interstellar medium as well as stellar and galactic chemical evolution. The number of objects and their mass-loss behavior at different metallicities are essential ingredients for accurate predictions from stellar and galactic evolution calculations. However, B[e]SGs are not easily identified, as they share many characteristics with luminous blue variables (LBVs) in their quiescent (hot) phase. We present medium-resolution near-infrared K-band spectra for four stars in M 31, which have been assigned a hot LBV (candidate) status. Applying diagnostics that were recently developed to distinguish B[e]SGs from hot LBVs, we classify two of the objects as bonafide LBVs; one of them currently in outburst. In addition, we firmly classify the two stars 2MASS J00441709+4119273 and 2MASS J00452257+4150346 as the first B[e]SGs in M 31 based on strong CO band emission detected in their spectra, and infrared colors typical for this class of stars.

  16. Theoretical characterization of quaternary iridium based hydrides NaAeIrH{sub 6} (Ae = Ca, Ba and Sr)

    Energy Technology Data Exchange (ETDEWEB)

    Bouras, S. [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Ghebouli, B., E-mail: bghebouli@yahoo.fr [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Benkerri, M. [Laboratory of Studies Surfaces and Interfaces of Solids Materials, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Ghebouli, M.A., E-mail: med.amineghebouli@yahoo.fr [Microelectronic Laboratory (LMSE), University of Bachir Ibrahimi, Bordj-Bou-Arreridj 34000 (Algeria); Research Unit on Emerging Materials (RUEM), University of Setif 1, 19000 (Algeria); Choutri, H. [Microelectronic Laboratory (LMSE), University of Bachir Ibrahimi, Bordj-Bou-Arreridj 34000 (Algeria); Louail, L.; Chihi, T.; Fatmi, M. [Research Unit on Emerging Materials (RUEM), University of Setif 1, 19000 (Algeria); Bouhemadou, A. [Laboratory for Developing New Materials and Their Characterization, Department of Physics, Faculty of Science, University of Setif 1, 19000 (Algeria); Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R.; Khachai, H. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria)

    2015-01-15

    The quaternary iridium based hydrides NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) are promising candidates as hydrogen storage materials. We have studied the structural, elastic, electronic, optical and thermodynamic properties of NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) within the generalized gradient approximation, the local density approximation (LDA) and mBj in the frame of density functional perturbation theory. These alloys have a large indirect Γ–X band gap. The thermodynamic functions were computed using the phonon density of states. The origin of the possible transitions from valence band to conduction band was illustrated. By using the complex dielectric function, the optical properties such as absorption, reflectivity, loss function, refractive index and optical conductivity have been obtained. - Graphical abstract: Real and imaginary parts of the dielectric function, the absorption spectrum α(ω), reflectivity R(ω) and energy-loss spectrum L(ω). - Highlights: • NaAeIrH{sub 6} (Ae = Ca, Ba and Sr) alloys have been investigated. • The elastic moduli, energy gaps are predicted. • The optical and thermal properties were studied.

  17. Atmospheric composition and structure of HD209458b

    CERN Document Server

    Désert, J -M; Etangs, A Lecavelier des; Sing, D; Ehrenreich, D; Hébrard, G; Ferlet, R

    2008-01-01

    Transiting planets like HD209458b offer a unique opportunity to scrutinize their atmospheric composition and structure. Transit spectroscopy probes the transition region between the day and night sides, called limb. We present a re-analysis of existing archived HST/STIS transmission spectra of HD209458b's atmosphere. From these observations we: Identify H2 Rayleigh scattering, derive the absolute Sodium abundance and quantify its depletion in the upper atmosphere, extract a stratospheric T-P profile with a temperature inversion and explain broad band absorptions with the presence of TiO and VO molecules in the atmosphere of this planet.

  18. Pit Profile Simulation for HD DVD Mastering Process

    Science.gov (United States)

    Yamamoto, Ryousuke; Matsumaru, Masaaki; Nakamura, Naomasa

    2007-06-01

    We constructed an HD DVD mastering process simulator on the basis of the cell removal model. In the exposure process, we simulated the exposure profile in the photoresist film. In the development process, we defined the density and development rate of the unit cell. We carried out iterative calculation for each unit cell dissolution. The development rate was approximated as the function of the exposure intensity profile. From the results, we were able to simulate the three-dimension (3D) pit profiles of HD DVD-ROM (read only memory). We clarified that our development rate equation is similar to Hirai et al. and Trefonas and Daniels’ type equation in semiconductor lithography.

  19. A Dark Energy Camera Search for Missing Supergiants in the LMC after the Advanced LIGO Gravitational-wave Event GW150914

    Science.gov (United States)

    Annis, J.; Soares-Santos, M.; Berger, E.; Brout, D.; Chen, H.; Chornock, R.; Cowperthwaite, P. S.; Diehl, H. T.; Doctor, Z.; Drlica-Wagner, A.; Drout, M. R.; Farr, B.; Finley, D. A.; Flaugher, B.; Foley, R. J.; Frieman, J.; Gruendl, R. A.; Herner, K.; Holz, D.; Kessler, R.; Lin, H.; Marriner, J.; Neilsen, E.; Rest, A.; Sako, M.; Smith, M.; Smith, N.; Sobreira, F.; Walker, A. R.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bernstein, R. A.; Bertin, E.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cenko, S. B.; Crocce, M.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Evrard, A. E.; Fernandez, E.; Fischer, J.; Fong, W.; Fosalba, P.; Fox, D. B.; Fryer, C. L.; Garcia-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Honscheid, K.; James, D. J.; Karliner, I.; Kasen, D.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Lima, M.; Maia, M. A. G.; Martini, P.; Metzger, B. D.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Peoples, J.; Petravic, D.; Plazas, A. A.; Quataert, E.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, R. C.; Stebbins, A.; Swanson, M. E. C.; Tarle, G.; Thaler, J.; Thomas, R. C.; Tucker, D. L.; Vikram, V.; Wechsler, R. H.; Weller, J.; Wester, W.; The DES Collaboration

    2016-06-01

    The collapse of a stellar core is expected to produce gravitational waves (GWs), neutrinos, and in most cases a luminous supernova. Sometimes, however, the optical event could be significantly less luminous than a supernova and a direct collapse to a black hole, where the star just disappears, is possible. The GW event GW150914 was detected by the LIGO Virgo Collaboration via a burst analysis that gave localization contours enclosing the Large Magellanic Cloud (LMC). Shortly thereafter, we used DECam to observe 102 deg2 of the localization area, including 38 deg2 on the LMC for a missing supergiant search. We construct a complete catalog of LMC luminous red supergiants, the best candidates to undergo invisible core collapse, and collected catalogs of other candidates: less luminous red supergiants, yellow supergiants, blue supergiants, luminous blue variable stars, and Wolf–Rayet stars. Of the objects in the imaging region, all are recovered in the images. The timescale for stellar disappearance is set by the free-fall time, which is a function of the stellar radius. Our observations at 4 and 13 days after the event result in a search sensitive to objects of up to about 200 solar radii. We conclude that it is unlikely that GW150914 was caused by the core collapse of a relatively compact supergiant in the LMC, consistent with the LIGO Collaboration analyses of the gravitational waveform as best interpreted as a high mass binary black hole merger. We discuss how to generalize this search for future very nearby core-collapse candidates.

  20. UV spectroscopy of the blue supergiant SBW1: the remarkably weak wind of a SN 1987A analog

    OpenAIRE

    Smith, Nathan; Groh, Jose H.; France, Kevin; McCray, Richard

    2016-01-01

    The Galactic blue supergiant SBW1 with its circumstellar ring nebula represents the best known analog of the progenitor of SN 1987A. High-resolution imaging has shown H-alpha and IR structures arising in an ionized flow that partly fills the ring's interior. To constrain the influence of the stellar wind on this structure, we obtained an ultraviolet (UV) spectrum of the central star of SBW1 with the HST Cosmic Origins Spectrograph (COS). The UV spectrum shows none of the typical wind signatur...

  1. Outflowing disk formation in B[e] supergiants due to rotation and bi--stability in radiation driven winds

    CERN Document Server

    Cure, M; Cidale, L

    2005-01-01

    The effects of rapid rotation and bi-stability upon the density contrast between the equatorial and polar directions of a B[e] supergiant are re-investigated. Based upon a new slow solution for different high rotational radiation driven winds (Cur\\'e 2004) and the fact that bi--stability allows a change in the line--force parameters ($\\alpha$, $k$, and $\\delta$), the equatorial densities are about $10^2$--$10^4$ times higher than the polar ones. These values are in qualitative agreement with the observations.

  2. The VLT-FLAMES Tarantula Survey V. The peculiar B[e]-like supergiant, VFTS698, in 30 Doradus

    OpenAIRE

    Dunstall, P. R.; Fraser, M; Clark, J. S.; Crowther, P. A.; Dufton, P. L.; Evans, C J; Lennon, D.J.; Soszynski, I.; Taylor, W.D.; Vink, J. S.

    2012-01-01

    Aims. We present an analysis of a peculiar supergiant B-type star (VFTS698/Melnick 2/Parker 1797) in the 30 Doradus region of the Large Magellanic Cloud which exhibits characteristics similar to the broad class of B[e] stars. Methods. We analyse optical spectra from the VLT-FLAMES survey, together with archival optical and infrared photometry and X-ray imaging to characterise the system. Results. We find radial velocity variations of around 400 kms−1 in the high excitation Si iv...

  3. Fast Oblivious AES A Dedicated application of the MiniMac protocol

    DEFF Research Database (Denmark)

    Zakarias, Rasmus Winther; Damgård, Ivan Bjerre

    2015-01-01

    ]. They presented an optimized implementation of the so-called MiniMac protocol [DZ13] that runs in the pre-processing model, and applied this to a binary AES circuit. In this paper we de- scribe how to dedicate the pre-processing to the structure of AES, which improves significantly the throughput and latency...

  4. Phylogenetic and temporal dynamics of human immunodeficiency virus type 1 CRF01_AE in China.

    Directory of Open Access Journals (Sweden)

    Jingrong Ye

    Full Text Available To explore the epidemic history of HIV-1 CRF01_AE in China, 408 fragments of gag gene sequences of CRF01_AE sampled in 2002-2010 were determined from different geographical regions and risk populations in China. Phylogenetic analysis indicates that the CRF01_AE sequences can be grouped into four clusters, suggesting that at least four genetically independent CRF01_AE descendants are circulating in China, of which two were closely related to the isolates from Thailand and Vietnam. Cluster 1 has the most extensive distribution in China. In North China, cluster 1 and cluster 4 were mainly transmitted through homosexuality.The real substance of the recent HIV-1 epidemic in men who have sex with men(MSM of North China is a rapid spread of CRF01_AE, or rather two distinctive natives CRF01_AE.The time of the most recent common ancestor (tMRCA of four CRF01_AE clusters ranged from the years 1990.9 to 2003.8 in different regions of China. This is the first phylogenetic and temporal dynamics study of HIV-1 CRF01_AE in China.

  5. Draft Genome Sequence of Brevibacterium linens AE038-8, an Extremely Arsenic-Resistant Bacterium.

    Science.gov (United States)

    Maizel, Daniela; Utturkar, Sagar M; Brown, Steven D; Ferrero, Marcela A; Rosen, Barry P

    2015-01-01

    To understand the arsenic biogeocycles in the groundwaters at Tucumán, Argentina, we isolated Brevibacterium linens sp. strain AE38-8, obtained from arsenic-contaminated well water. This strain is extremely resistant to arsenicals and has arsenic resistance (ars) genes in its genome. Here, we report the draft genome sequence of B. linens AE38-8. PMID:25883298

  6. Draft Genome Sequence of Brevibacterium linens AE038-8, an Extremely Arsenic-Resistant Bacterium

    OpenAIRE

    Maizel, Daniela; Utturkar, Sagar M.; Brown, Steven D.; Ferrero, Marcela A.; ROSEN, BARRY P.

    2015-01-01

    To understand the arsenic biogeocycles in the groundwaters at Tucumán, Argentina, we isolated Brevibacterium linens sp. strain AE38-8, obtained from arsenic-contaminated well water. This strain is extremely resistant to arsenicals and has arsenic resistance (ars) genes in its genome. Here, we report the draft genome sequence of B. linens AE38-8.

  7. Phylogenetic and temporal dynamics of human immunodeficiency virus type 1 CRF01_AE in China.

    Science.gov (United States)

    Ye, Jingrong; Xin, Ruolei; Yu, Shuangqing; Bai, Lishi; Wang, Weishi; Wu, Tingchen; Su, Xueli; Lu, Hongyan; Pang, Xinghuo; Yan, Hong; Feng, Xia; He, Xiong; Zeng, Yi

    2013-01-01

    To explore the epidemic history of HIV-1 CRF01_AE in China, 408 fragments of gag gene sequences of CRF01_AE sampled in 2002-2010 were determined from different geographical regions and risk populations in China. Phylogenetic analysis indicates that the CRF01_AE sequences can be grouped into four clusters, suggesting that at least four genetically independent CRF01_AE descendants are circulating in China, of which two were closely related to the isolates from Thailand and Vietnam. Cluster 1 has the most extensive distribution in China. In North China, cluster 1 and cluster 4 were mainly transmitted through homosexuality.The real substance of the recent HIV-1 epidemic in men who have sex with men(MSM) of North China is a rapid spread of CRF01_AE, or rather two distinctive natives CRF01_AE.The time of the most recent common ancestor (tMRCA) of four CRF01_AE clusters ranged from the years 1990.9 to 2003.8 in different regions of China. This is the first phylogenetic and temporal dynamics study of HIV-1 CRF01_AE in China. PMID:23365653

  8. 15 CFR 758.1 - The Shipper's Export Declaration (SED) or Automated Export System (AES) record.

    Science.gov (United States)

    2010-01-01

    ... transmits data via AES must be a certified AES participant in accordance with 15 CFR 30.60 of the FTSR. The.... 1 to part 740 of the EAR regardless of value (see 15 CFR 30.55); (2) For all exports subject to the...) is over $2,500, except as exempted by the Foreign Trade Statistics Regulations (FTSR) in 15 CFR...

  9. Low-area hardware implementations of CLOC, SILC and AES-OTR

    DEFF Research Database (Denmark)

    Banik, Subhadeep; Bogdanov, Andrey; Minematsu, Kazuhiko

    2016-01-01

    The most compact implementation of the AES-128 algorithm was the 8-bit serial circuit proposed in the work of Moradi et. al. (Eurocrypt 2011). The circuit has an 8-bit datapath and occupies area equivalent to around 2400 GE. Since many authenticated encryption modes use the AES-128 algorithm as t...

  10. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii

    DEFF Research Database (Denmark)

    Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.;

    2014-01-01

    AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations of t...

  11. 76 FR 4089 - Proposed Information Collection; Comment Request; Automated Export System (AES) Program

    Science.gov (United States)

    2011-01-24

    ... marketing strategies as well as provide a means for the assessment of the impact of exports on the domestic... Census Bureau Proposed Information Collection; Comment Request; Automated Export System (AES) Program... INFORMATION: I. Abstract The Automated Export System (AES), is the instrument used for collecting export...

  12. Far-ultraviolet energy distributions of the metal-poor A stars HD 109995 and HD 161817

    Science.gov (United States)

    Boehm-Vitense, E.

    1981-01-01

    Low-resolution IUE spectra at wavelengths between 1300 and 3400 A of the metal-poor stars HD 109995 (A1p) and HD 161817 (A4p) have been compared with model-atmosphere energy distributions computed by Kurucz (1979). Good overall agreement is found. Effective temperatures, metal abundances, and angular diameters could be determined. Assuming an absolute visual magnitude of 0.7, the previously determined gravity log = 3 yields masses of 0.5 solar masses for both stars. It is found that the theoretical UBV colors calculated earlier agree reaonably well with the ones observed for these stars.

  13. One AES S-box to increase complexity and its cryptanalysis

    Institute of Scientific and Technical Information of China (English)

    Liu Jingmei; Wei Baodian; Wang Xinmei

    2007-01-01

    It is well known that the algebraic expression of AES S-box is very simple and only 9 terms are involved.Hence, AES security is suspected although there is no vulnerability on it so far.To eliminate the weakness of extremely small terms in the algebraic expression of AES S-box, one improved AES S-box is proposed, which preserves the algebraic degree invariable but significantly increases the number of its algebraic expression terms from 9 to 255.At the same time, Boolean function has good characters in balance and strict avalanche criterion (SAC), etc.Finally, it is proved that the improved AES S-box scheme is secure against the powerful known differential and linear cryptanalysis.

  14. The HARPS search southern extra-solar planets. VII. A very hot jupiter orbiti HD 212301

    DEFF Research Database (Denmark)

    Lo Curto, G.; Mayor, M.; Clausen, J.V.;

    2006-01-01

    Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs......Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs...

  15. Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in Supergiant Fast X-ray Transient and classical Supergiant X-ray Binaries

    CERN Document Server

    Gimenez-Garcia, A; Torrejon, J M; Oskinova, L; Martinez-Nunez, S; Hamann, W -R; Rodes-Roca, J J; Gonzalez-Galan, A; Alonso-Santiago, J; Gonzalez-Fernandez, C; Bernabeu, G; Sander, A

    2016-01-01

    Classical Supergiant X-ray Binaries (SGXBs) and Supergiant Fast X-ray Transients (SFXTs) are two types of High-mass X-ray Binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyse the spectra of each star in detail and derive their stellar and wind properties. We compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. We find that the stellar para...

  16. ASASSN-14ae: A Tidal Disruption Event at 200 Mpc

    CERN Document Server

    Holoien, Thomas W -S; Bersier, D; Kochanek, C S; Stanek, K Z; Shappee, B J; Grupe, D; Basu, U; Beacom, J F; Brimacombe, J; Brown, J S; Davis, A B; Jencson, J; Pojmanski, G; Szczygiel, D M

    2014-01-01

    ASASSN-14ae is a candidate tidal disruption event (TDE) found at the center of SDSS J110840.11+340552.2 ($d\\simeq200$ Mpc) by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global array of 14-cm telescopes. The host galaxy is an early type spiral with no signs of an active galactic nucleus (AGN) and with little recent star formation. We present follow-up photometric and spectroscopic observations of the source, including optical data from ground-based telescopes and ultraviolet and optical data from Swift. From blackbody fits to the host-subtracted spectral energy distribution, we find that the transient had a peak luminosity of $L\\simeq8\\times10^{43}$ erg s$^{-1}$ and a total integrated energy of $E\\simeq1.5\\times10^{50}$ ergs over the $\\sim3$ months of observations presented. The blackbody temperature of the transient remains roughly constant at $T\\sim20,000$ K while the luminosity declines by nearly 1.5 orders of magnitude during this time, a drop that is most consistent with an exponential, $L\\p...

  17. Spectral Analysis and Classification of Herbig Ae/Be Stars

    Science.gov (United States)

    Hernández, Jesús; Calvet, Nuria; Briceño, César; Hartmann, Lee; Berlind, Perry

    2004-03-01

    We present an analysis of the optical spectra of 75 early-type emission-line stars, many of which have been classified previously as Herbig Ae/Be (HAeBe) stars. Accurate spectral types were derived for 58 members of the sample; high continuum veiling, contamination by nonphotospheric absorption features, or a composite binary spectrum prevented accurate spectral typing for the rest. Approximately half of our sample exhibited [O I] λ6300 forbidden-line emission down to our detection limit of 0.1 Å equivalent width; a third of the sample exhibited Fe II emission (multiplet 42). A subset of 11 of the HAeBe sample showed abnormally strong Fe II absorption; 75% of this subset are confirmed UX Ori objects. Combining our spectral typing results with photometry from the literature, we confirm previous findings of high values of total-to-selective extinction (RV~5) in our larger sample, suggesting significant grain growth in the environments of HAeBe stars. With this high value of RV, the vast majority of HAeBe stars appear younger than with the standard RV=3.1 extinction law and are more consistent with being pre-main-sequence objects.

  18. Optical spectroscopic variability of Herbig Ae/Be stars

    CERN Document Server

    Mendigutía, I; Montesinos, B; Mora, A; Oudmaijer, R D; Merín, B; Meeus, G

    2011-01-01

    We analysed 337 multi-epoch optical spectra of 38 Herbig Ae/Be (HAeBe) stars to gain insights into the variability behaviour of the circumstellar (CS) atomic gas. Equivalent widths (EWs) and line fluxes of the Halpha, [OI]6300, HeI5876 and NaID lines were obtained for each spectrum; the Halpha line width at 10% of peak intensity (W10) and profile shapes were also measured and classified. The mean line strengths and relative variabilities were quantified for each star. Simultaneous optical photometry was used to estimate the line fluxes. We present a homogeneous spectroscopic database of HAeBe stars. The lines are variable in practically all stars and timescales, although 30 % of the objects show a constant EW in [OI]6300, which is also the only line that shows no variability on timescales of hours. The HeI5876 and NaID EW relative variabilities are typically the largest, followed by those in [OI]6300 and Halpha. The EW changes can be larger than one order of magnitude for the HeI5876 line, and up to a factor ...

  19. Chandra High Energy Transmission Grating Spectrum of AE Aquarii

    CERN Document Server

    Mauche, Christopher W

    2009-01-01

    (Abridged) The results of a Chandra X-ray Observatory High-Energy Transmission Grating (HETG) observation of the nova-like cataclysmic binary AE Aqr are described. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy, from sigma~1 eV for O VIII to sigma~5.5 eV for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K)=7.16, has a width sigma=0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d=100 pc, the total emission measure EM=8.0E53 cm^-3 and the 0.5-10 keV luminosity L_X=1.1E31 erg/s. Second, based on the f/(i+r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the He alpha triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spec...

  20. High Dispersion Absorption-line Spectroscopy of AE Aqr

    CERN Document Server

    Echevarria, J; Costero, R; Zharikov, S; Michel, R

    2008-01-01

    High-dispersion time-resolved spectroscopy of the unique magnetic cataclysmic variable AE Aqr is presented. A radial velocity analysis of the absorption lines yields K_2 = 168.7+/- 1 km/s. Substantial deviations of the radial velocity curve from a sinusoid are interpreted in terms of intensity variations over the secondary star's surface. A complex rotational velocity curve as a function of orbital phase is detected which has a modulation frequency of twice the orbital frequency, leading to an estimate of the binary inclination angle that is close to 70^o. The minimum and maximum rotational velocities are used to indirectly derive a mass ratio of q= 0.6 and a radial velocity semi-amplitude of the white dwarf of K_1 = 101+/-3 km/s. We present an atmospheric temperature indicator, based on the absorption line ratio of Fe I and Cr I lines, whose variation indicates that the secondary star varies from K0 to K4 as a function of orbital phase. The ephemeris of the system has been revised, using more than one thousa...

  1. Test and acceptance from the AE point of view

    International Nuclear Information System (INIS)

    The power industry has undergone the transition from utilizing construction engineers for startup activities to utilizing test engineers who are responsible for the preparation or execution of a formal test program. This has come about because testing has been given sufficient importance to justify those participating within the industry to establish it as a specialty phase apart from engineering/design and construction. Presently testing is being conducted by those organizations that have either engineered and/or constructed the unit which may be a position of conflict in regards to unbiased test. The tester (third party) concept promotes the repetition, independence, and expertise of a test organization responsible to the utility for certifying that each system has been tested to the design criteria established by others. A move to this concept should result in better generating stations with higher availability because it has been completely tested by an organization with this sole contractual responsibility. The AE, NSSS, and utility would all benefit with possibly no additional costs incurred

  2. AE的AE1MKⅢSE音箱

    Institute of Scientific and Technical Information of China (English)

    梓门

    2011-01-01

    @@ 1987年内尔·麦克埃文(Neil McEwen)和史蒂夫·泰勒(Steve Taylor)在英国伦敦西部的格洛斯特郡(Gloucester)成立了AE(Acoustic Energy Limited,意为"电声力量有限公司"),工厂设在郊区的科茨沃尔德区(Cotswold),产品的设计师由后来成名的菲尔琼斯(Phil Jones)担任. 1995年,AE产品的经营变为英国开发、设计和营销.生产制造由马来西亚的合作OEM厂担任.其中1992年-1995年也曾有一段时间由中国大陆的OEM厂担任部分产品的生.产品标签标注为:"DESIGNED AND ENGINEERED BY ACOUSTIC ENERGYLIMITED ENGLAND"(英国AE公司设计和监制)这可不能说是英国原产.不过,据说AE的一些高端产品目前仍然坚持的英国制造但是具体的型号或系列不详.

  3. Chemical qualification of sodium diuranate by ICP-AES method

    International Nuclear Information System (INIS)

    The present paper explains the utility of dual solvent extraction system comprising Tri n-butyl Phosphate (TBP) in CCl4 solvent for bulk separation of Uranium matrix in nitric acid medium followed by Tri n-Octyl Phosphine Oxide (TOPO) in CCl4 solvent for removal of traces of Uranium present in aqueous phase. The method involves digestion of SDU in 1:1 HNO3 followed by filtration of resultant solution. The residue was washed thrice with 1:1 HNO3 for complete leaching of uranium and impurities into filtrate and its subsequent evaporation to near dryness followed by solvent extraction after bringing it into 4N HNO3 medium. Several experimental parameters such as concentration of extractant, acid strength, organic to aqueous phase ratio, Number of repeated extractions are studied to optimize solvent extraction conditions. Also recovery study of individual elements during extraction has been carried out in presence of Uranium. Measurement conditions of ICP-AES and AAS also given in the paper

  4. Optical Mass Flow Diagnostics in Herbig Ae/Be Stars

    CERN Document Server

    Cauley, P Wilson

    2015-01-01

    We examine a broad range of mass flow diagnostics in a large sample of Herbig Ae/Be stars (HAEBES) using high resolution optical spectra. The H-beta and He I 5876 angstrom lines show the highest incidence of P-Cygni (30%) and inverse P-Cygni (14%) morphologies, respectively. The Fe II 4924 angstrom line also shows a large incidence of P-Cygni profiles (11%). We find support for many of the conclusions reached in a study based on the analysis of the He I 10830 angstrom line in a large sample of HAEBES. Namely, HAEBES exhibit smaller fractions of both blue-shifted absorption (i.e. mass outflow) and red-shifted absorption (i.e. mass infall or accretion) than their lower mass cousins, the classical T Tauri stars (CTTSs). In particular, the optical data supports the conclusion that HAEBES displaying red-shifted absorption, in general, show maximum red-shifted absorption velocities that are smaller fractions of their stellar escape velocities than is found for CTTSs. This suggests that HAEBE accretion flows are ori...

  5. Application and detection of (14)c-hd in two mouse models.

    Science.gov (United States)

    Logan, Thomas P; Shutz, Michael; Schulz, Susan M; Railer, Roy; Ricketts, Karen M; Casillas, Robert P

    2002-01-01

    The CD1-haired mouse and the SKH-hairless mouse are two animal models that have been used to evaluate sulfur mustard (HD) exposure and protection in our laboratory. In a recent study we observed that a substance P inhibitor protected the haired mouse ear against an HD solution, but the same drug was not successful in protecting the hairless mouse against HD vapor. This experiment prompted us to compare HD exposures between these models. We determined the (14)C content in the skin after exposures to HD containing (14)C-HD. Rate curves were generated for applications of (1) HD in methylene chloride to the haired mouse ear; (2) HD in methylene chloride to the hairless mouse dorsal skin; and (3) saturated HD vapor to the hairless mouse dorsal skin for 6 min. The curves showed a reduction in (14)C disintegrations per min in animals euthanized 0 to 2 h postexposure. The largest percentage of decrease of (14)C content in skin occurred within 30 min of HD challenge for all exposures. An 8-mm skin-punch biopsy and a 14-mm annular skin section surrounding the region of the 8-mm skin punch were taken from the hairless mouse dorsal skin exposed to HD in methylene chloride. The ratio of the (14)C content in the 8-mm skin punch to that in the surrounding 14-mm annular skin section was 7.3, demonstrating that the HD application spreads beyond the initially biopsied site. A concentration/time value of 6.3 mug/cm(2)/min was determined by counting skin (14)C disintegrations per minute in animals euthanized immediately after exposure to saturated HD vapor. Determinations of the amount of HD showed that similar quantities of HD, 0.4 mg, were detected on each model. These results contribute to a better quantitative understanding of HD application in the haired and hairless mouse models.

  6. A spectroscopic analysis of the chemically peculiar star HD207561

    CERN Document Server

    Joshi, S; Martinez, P; Sachkov, M; Joshi, Y C; Seetha, S; Chakradhari, N K; Mary, D L; Girish, V; Ashoka, B N

    2012-01-01

    In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is s...

  7. The Spectrum of HD 3651B: An Extrasolar Nemesis?

    CERN Document Server

    Burgasser, A J

    2006-01-01

    I present detailed analysis of the near-infrared spectrum of HD 3651B, a faint, co-moving wide companion to the nearby planet-hosting star HD 3651. The presence of strong H_2O and CH_4 absorption bands confirm this source as a late T-type brown dwarf with spectral type T8. Application of the technique of Burgasser, Burrows & Kirkpatrick yields T_eff = 840+/-80 K, log(g) = 4.9+/-0.2, M = 30+/-10 M_Jup and an age in the range 0.7-3.4 Gyr, making HD 3651B a slightly warmer analog to the field T8 2MASS 0415-0935. The derived age for this companion is somewhat better constrained than estimates for its primary, which ranges from ~2 Gyr to >12 Gyr. As a widely orbiting massive object to a known planetary system that could potentially harbor terrestrial planets in its habitable zone, HD 3651B may play the role of Nemesis in this system.

  8. NV-CMOS HD camera for day/night imaging

    Science.gov (United States)

    Vogelsong, T.; Tower, J.; Sudol, Thomas; Senko, T.; Chodelka, D.

    2014-06-01

    SRI International (SRI) has developed a new multi-purpose day/night video camera with low-light imaging performance comparable to an image intensifier, while offering the size, weight, ruggedness, and cost advantages enabled by the use of SRI's NV-CMOS HD digital image sensor chip. The digital video output is ideal for image enhancement, sharing with others through networking, video capture for data analysis, or fusion with thermal cameras. The camera provides Camera Link output with HD/WUXGA resolution of 1920 x 1200 pixels operating at 60 Hz. Windowing to smaller sizes enables operation at higher frame rates. High sensitivity is achieved through use of backside illumination, providing high Quantum Efficiency (QE) across the visible and near infrared (NIR) bands (peak QE cinematography/broadcast systems, biofluorescence/microscopy imaging, day/night security and surveillance, and other high-end applications which require HD video imaging with high sensitivity and wide dynamic range. The camera comes with an array of lens mounts including C-mount and F-mount. The latest test data from the NV-CMOS HD camera will be presented.

  9. The flux-weighted gravity-luminosity relationship of blue supergiant stars as a constraint for stellar evolution

    CERN Document Server

    Meynet, Georges; Georgy, Cyril

    2015-01-01

    (abridged) The flux-weighted gravity-luminosity relationship (FGLR) of blue supergiant stars (BSG) links their absolute magnitude to the spectroscopically determined flux-weighted gravity log g = Teff^4. BSG are the brightest stars in the universe at visual light and the application of the FGLR has become a powerful tool to determine extragalactic distances. Observationally, the FGLR is a tight relationship with only small scatter. It is, therefore, ideal to be used as a constraint for stellar evolution models. The goal of this work is to investigate whether stellar evolution can reproduce the observed FGLR and to develop an improved foundation of the FGLR as an extragalactic distance indicator. We use different grids of stellar models for initial masses between 9 and 40 Msun, for metallicities between Z = 0.002 and 0.014, with and without rotation, computed with various mass loss rates during the red supergiant phase. For each of these models we discuss the details of post-main sequence evolution and constru...

  10. A Spectroscopic Study of Blue Supergiant Stars in the Sculptor Galaxy NGC 55: Chemical Evolution and Distance

    Science.gov (United States)

    Kudritzki, R. P.; Castro, N.; Urbaneja, M. A.; Ho, I.-T.; Bresolin, F.; Gieren, W.; Pietrzyński, G.; Przybilla, N.

    2016-10-01

    Low-resolution (4.5-5 Å) spectra of 58 blue supergiant stars distributed over the disk of the Magellanic spiral galaxy NGC 55 in the Sculptor group are analyzed by means of non-LTE techniques to determine stellar temperatures, gravities, and metallicities (from iron peak and α-elements). A metallicity gradient of -0.22 ± 0.06 dex/R 25 is detected. The central metallicity on a logarithmic scale relative to the Sun is [Z] = -0.37 ± 0.03. A chemical evolution model using the observed distribution of column densities of the stellar and interstellar medium gas mass reproduces the observed metallicity distribution well and reveals a recent history of strong galactic mass accretion and wind outflows with accretion and mass-loss rates of the order of the star formation rate. There is an indication of spatial inhomogeneity in metallicity. In addition, the relatively high central metallicity of the disk confirms that two extraplanar metal-poor H ii regions detected in previous work 1.13 to 2.22 kpc above the galactic plane are ionized by massive stars formed in situ outside the disk. For a subsample of supergiants, for which Hubble Space Telescope photometry is available, the flux-weighted gravity-luminosity relationship is used to determine a distance modulus of 26.85 ± 0.10 mag.

  11. Radiative hydrodynamics simulations of red supergiant stars. III. Spectro-photocentric variability, photometric variability, and consequences on Gaia measurements

    CERN Document Server

    Chiavassa, A; Jorissen, A; Sacuto, S; Babusiaux, C; Freytag, B; Ludwig, H -G; Cruzalebes, P; Rabbia, Y; Spang, A; Chesneau, O

    2010-01-01

    Context. It has been shown that convection in red supergiant stars gives rise to large granules causing surface inhomogeneities together with shock waves in the photosphere. The resulting motion of the photocenter (on time scales ranging from months to years) could possibly have adverse effects on the parallax determination with Gaia. Aims. We explore the impact of the granulation on the photocentric and photometric variability. We quantify these effects in order to better characterize the error possibly altering the parallax. Methods. We use 3D radiative-hydrodynamics simulations of convection with CO5BOLD and the post-processing radiative transfer code OPTIM3D to compute intensity maps and spectra in the Gaia G band [325-1030 nm]. Results. We provide astrometric and photometric predictions from 3D simulations of RSGs that are used to evaluate the degradation of the astrometric parameters of evolved stars derived by Gaia. We show from RHD simulations that a supergiant like Betelgeuse exhibits a photocentric ...

  12. Giant outburst from the supergiant fast X-ray transient IGR J17544-2619: accretion from a transient disc?

    CERN Document Server

    Romano, P; Mangano, V; Esposito, P; Israel, G; Tiengo, A; Campana, S; Ducci, L; Ferrigno, C; Kennea, J A

    2015-01-01

    Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries associated with OB supergiant companions and characterised by an X-ray flaring behaviour whose dynamical range reaches 5 orders of magnitude on timescales of a few hundred to thousands of seconds. Current investigations concentrate on finding possible mechanisms to inhibit accretion in SFXTs and explain their unusually low average X-ray luminosity. We present the Swift observations of an exceptionally bright outburst displayed by the SFXT IGR J17544-2619 on 2014 October 10 when the source achieved a peak luminosity of $3\\times10^{38}$ erg s$^{-1}$. This extends the total source dynamic range to $\\gtrsim$10$^6$, the largest (by a factor of 10) recorded so far from an SFXT. Tentative evidence for pulsations at a period of 11.6 s is also reported. We show that these observations challenge, for the first time, the maximum theoretical luminosity achievable by an SFXT and propose that this giant outburst was due to the formation of a transient ac...

  13. Herschel SPIRE and PACS observations of the red supergiant VY CMa: analysis of the molecular line spectra

    CERN Document Server

    Matsuura, Mikako; Barlow, M J; Swinyard, B M; Royer, P; Cernicharo, J; Decin, L; Wesson, R; Polehampton, E T; Blommaert, J A D L; Groenewegen, M A T; Van de Steene, G C; van Hoof, P A M

    2013-01-01

    We present an analysis of the far-infrared and submillimetre molecular emission line spectrum of the luminous M-supergiant VY CMa, observed with the SPIRE and PACS spectrometers aboard the Herschel Space Observatory. Over 260 emission lines were detected in the 190-650-micron SPIRE FTS spectra, with one-third of the observed lines being attributable to H2O. Other detected species include CO, 13CO, H2^18O, SiO, HCN, SO, SO2, CS, H2S, and NH3. Our model fits to the observed 12CO and 13CO line intensities yield a 12C/13C ratio of 5.6+-1.8, consistent with measurements of this ratio for other M supergiants, but significantly lower than previously estimated for VY CMa from observations of lower-J lines. The spectral line energy distribution for twenty SiO rotational lines shows two temperature components: a hot component at 1000 K, which we attribute to the stellar atmosphere and inner wind, plus a cooler ~200 K component, which we attribute to an origin in the outer circumstellar envelope. We fit the line fluxes ...

  14. Multiwavelength study of the fast rotating supergiant high-mass X-ray binary IGR J16465-4507

    CERN Document Server

    Chaty, Sylvain; Negueruela, Ignacio; Coleiro, Alexis; Castro, Norberto; Simon-Diaz, Sergio; Heras, Juan Antonio Zurita; Goldoni, Paolo; Goldwurm, Andrea

    2016-01-01

    Since its launch, the X-ray and gamma-ray observatory INTEGRAL satellite has revealed a new class of high-mass X-ray binaries (HMXB) displaying fast flares and hosting supergiant companion stars. Optical and infrared (OIR) observations in a multi-wavelength context are essential to understand the nature and evolution of these newly discovered celestial objects. The goal of this multiwavelength study (from ultraviolet to infrared) is to characterise the properties of IGR J16465-4507, to confirm its HMXB nature and that it hosts a supergiant star. We analysed all OIR, photometric and spectroscopic observations taken on this source, carried out at ESO facilities. Using spectroscopic data, we constrained the spectral type of the companion star between B0.5 and B1 Ib, settling the debate on the true nature of this source. We measured a high rotation velocity of v = 320 +/- 8 km/s from fitting absorption and emission lines in a stellar spectral model. We then built a spectral energy distribution from photometric ob...

  15. Unveiling Type IIb Supernova Progenitors: SN 2011hs from a Supergiant Star

    Science.gov (United States)

    Bufano, F.

    2014-10-01

    Type IIb Supernovae are the final evolutionary stage of massive stars that were able to retain only a thin (lesssim 1 M_{odot}) H/He external envelope at the time of the explosion. The mechanism of mass-loss that made such final structure possible and the nature of such progenitor stars are still open issues. We present the results obtained from the study of a sample of Type IIb SNe, in particular, of SN 2011hs (Bufano et al., 2013, MNRAS submitted). SN 2011hs was a relatively faint (M_{B} = -15.6 mag) and red Type IIb SN, characterized by a narrow light curve shape. Its spectral evolution showed the metamorphosis typical of this class of SN, from spectra dominated by H I lines to spectra where He I features dominate, but with broad absorption line profiles indicating high expansion velocities. Modeling the light curve of SN 2011hs and its velocity evolution with hydrodynamical calculations, we estimated that the SN is consistent with the explosion of a 3-4 M_{odot} He-core star, from a main sequence mass of 12-15 M_{odot}, ejecting a ^{56}Ni mass equal to 0.04 M_{odot} and characterized by an explosion energy of E≍ 8.5× 10^{50} erg s^{-1}. Based on the light curve evolution, we assumed that the explosion occurred 6 days before the discovery (2,455,872 ± 4 JD), resulting in an adiabatic cooling phase lasting 8 days, similarly to SN 1993J. Since the duration and the decreasing rate of the cooling branch depends mainly on the progenitor size, we could infer from it a progenitor radius of ≍ 500-600 R_{odot}, like a supergiant star. Our modeling rules out models with He core mass >5 M_{odot}, i.e. main sequence masses above 20 M_{odot}. Such a lower limit for the progenitor mass could indicate the possibility of a binary origin, although the radio light curve does not show strong deviations, typically signature of the presence of a companion star.

  16. Discovery of the First B[e] Supergiants in M 31

    Science.gov (United States)

    Kraus, M.; Cidale, L. S.; Arias, M. L.; Oksala, M. E.; Borges Fernandes, M.

    2014-01-01

    B[e] supergiants (B[e]SGs) are transitional objects in the post-main sequence evolution of massive stars. The small number of B[e]SGs known so far in the Galaxy and the Magellanic Clouds indicates that this evolutionary phase is short. Nevertheless, the strong aspherical mass loss occurring during this phase, which leads to the formation of rings or disk-like structures, and the similarity to possible progenitors of SN1987 A emphasize the importance of B[e]SGs for the dynamics of the interstellar medium as well as stellar and galactic chemical evolution. The number of objects and their mass-loss behavior at different metallicities are essential ingredients for accurate predictions from stellar and galactic evolution calculations. However, B[e]SGs are not easily identified, as they share many characteristics with luminous blue variables (LBVs) in their quiescent (hot) phase. We present medium-resolution near-infrared K-band spectra for four stars in M 31, which have been assigned a hot LBV (candidate) status. Applying diagnostics that were recently developed to distinguish B[e]SGs from hot LBVs, we classify two of the objects as bonafide LBVs; one of them currently in outburst. In addition, we firmly classify the two stars 2MASS J00441709+4119273 and 2MASS J00452257+4150346 as the first B[e]SGs in M 31 based on strong CO band emission detected in their spectra, and infrared colors typical for this class of stars. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva

  17. Mode width fitting with a simple bayesian approach. Application to CoRoT targets HD 181420 and HD 49933

    CERN Document Server

    Gaulme, P; Boumier, P; 10.1051/0004-6361/200911920

    2010-01-01

    We investigate the asteroseismology of two solar-like targets as observed with the CoRoT satellite, with particular attention paid to the mode fitting. HD 181420 and HD 49933 are typical CoRoT solar-like targets (156 and 60-day runs). The low signal-to-noise ratio (SNR) of about 3-10 prevents us from unambiguously identifying the individual oscillation modes. In particular, convergence problems appear at the edges of the oscillation spectrum. HD 181420 and HD 49933 are typical CoRoT solar-like targets (156 and 60-day runs). The low signal-to-noise ratio (SNR) of about 3-10 prevents us from unambiguously identifying the individual oscillation modes. In particular, convergence problems appear at the edges of the oscillation spectrum. We apply a Bayesian approach to the analysis of these data. We compare the global fitting of the power spectra of this time series, obtained by the classical maximum likelihood (MLE) and the maximum a posteriori (MAP) estimators. We examine the impact of the choice of the priors up...

  18. THE DISCOVERY OF HD 37605c AND A DISPOSITIVE NULL DETECTION OF TRANSITS OF HD 37605b

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Sharon Xuesong; Wright, Jason T.; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Cochran, William; Endl, Michael; MacQueen, Phillip J. [McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Kane, Stephen R.; Von Braun, Kaspar [NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Boulevard, Box 9501, Nashville, TN 37209 (United States); Payne, Matthew J.; Ford, Eric B. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Antoci, Victoria; Dragomir, Diana; Matthews, Jaymie M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T1Z1 (Canada); Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard, E-mail: xxw131@psu.edu, E-mail: jtwright@astro.psu.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2012-12-10

    We report the radial velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P {approx} 55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of {approx}7.5 years with a low eccentricity and an Msin i of {approx}3.4 M{sub Jup}. Our discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey effort to provide precise ephemerides to long-period planets for transit follow-up. With a total of 137 radial velocity observations covering almost 8 years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using the predicted ephemeris, we performed a transit search for HD 37605b with the photometric data taken by the T12 0.8 m Automatic Photoelectric Telescope (APT) and the MOST satellite. Though the APT photometry did not capture the transit window, it characterized the stellar activity of HD 37605, which is consistent of it being an old, inactive star, with a tentative rotation period of 57.67 days. The MOST photometry enabled us to report a dispositive null detection of a non-grazing transit for this planet. Within the predicted transit window, we exclude an edge-on predicted depth of 1.9% at the >>10{sigma} level, and exclude any transit with an impact parameter b > 0.951 at greater than 5{sigma}. We present the BOOTTRAN package for calculating Keplerian orbital parameter uncertainties via bootstrapping. We made a comparison and found consistency between our orbital fit parameters calculated by the RVLIN package and error bars by BOOTTRAN with those produced by a Bayesian analysis using MCMC.

  19. Dynamic inhomogeneous S-Boxes design for efficient AES masking mechanisms

    Institute of Scientific and Technical Information of China (English)

    CHEN Yi-cheng; ZOU Xue-cheng; LIU Zheng-lin; CHEN Xiao-fei; HAN Yu

    2008-01-01

    It is an important challenge to implement a low- cost power analysis immune advanced encryption standard (AES) circuit. The previous study proves that substitution boxes (S-Boxes) in AES are prone to being attacked, and hard to mask for its non-linear characteristic. Besides, large amounts of circuit resources in chips and power consumption are spent in protecting S-Boxes against power analysis. Thus, a novel power analysis immune scheme is proposed, which divides the data-path of AES into two parts: inhomogeneous S-Boxes instead of fixed S-Boxes are selected randomly to disturb power and logic delay in the non-linear module; at the same time, the general masking strategy is applied in the linear part of AES. This improved AES circuit was synthesized with united microelectronics corporation (UMC) 0.25 μm 1.8 V complementary metal-oxide-semiconductor (CMOS) standard cell library, and correlation power analysis experiments were executed. The results demonstrate that this secure AES implementation has very low hardware cost and can enhance the AES security effectually against power analysis.

  20. AES-128在光模块中设计与实现

    Institute of Scientific and Technical Information of China (English)

    张鹏

    2015-01-01

    Design and implementation of AES-128 In optical module On November 26, 2001 AES(advanced encryp-tion standard)was announced. On May 26, 2002, AES was approved as effective standards, And now it has been re-cognized as one of the most secure encryption algorithm, widely used in various fields. Based on the the principle of AES encryption algorithm. This paper state how to apply AES on optical module. At last, the AES application pros-pect was forecast..%2001年11月26日AES高级加密标准发布,2002年5月26日被确认为有效的标准,目前被公认是最安全的加密算法之一,在各个领域中都得到广泛应用。文章在研究分析AES加密算法原理的基础上,阐述AES-128在光模块上具体应用及实现,并对AES应用前景进行展望。

  1. Design and Hardware Implementation of QoSS - AES Processor for Multimedia applications

    Directory of Open Access Journals (Sweden)

    Zeghid Medien

    2010-04-01

    Full Text Available For real-time applications, there are several factors (time, cost, power that are moving security considerations from a function centric perspective into a system architecture (hardware/software design issue. Advanced Encryption Standard (AES is used nowadays extensively in many network and multimedia applications to address security issues. The AES algorithm specifies three key sizes: 128, 192 and 256 bits offering different levels of security. To deal with the amount of application and intensive computation given by security mechanisms, we define and develop a QoSS (Quality of Security Service model for reconfigurable AES processor. QoSS has been designed and implemented to achieve a flexible trade-off between overheads caused by security services and system performance. The proposed architecture can provide up to 12 AES block cipher schemes within a reasonable hardware cost. We envisage a security vector in a fully functional QoSS request to include levels of service for the range of security service and mechanisms. Our unified hardware can run both the original AES algorithm and the extended AES algorithm (QoSS-AES. A novel on-the-fly AES encryption/ decryption design is also proposed for 128- , 192- , and 256-bit keys. The performance of the proposed processor has been analyzed in an MPEG4 video compression standard. The results revealed that the QoSS-AES processor is well suited to provide high security communication with low latencies. In our implementation based on Xilinx Virtex FPGAs, speed/area/power results from these processors are analyzed and shown to compare favorably with other well known FPGA based implementations.

  2. An empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich Asymptotic Giant Branch stars

    CERN Document Server

    Van Loon, J T; Zijlstra, A A; Loup, C; Loon, Jacco Th. van; Cioni, Maria-Rosa L.; Zijlstra, Albert A.; Loup, Cecile

    2005-01-01

    We present an empirical determination of the mass-loss rate as a function of stellar luminosity and effective temperature, for oxygen-rich dust-enshrouded Asymptotic Giant Branch stars and red supergiants. To this aim we obtained optical spectra of a sample of dust-enshrouded red giants in the Large Magellanic Cloud, which we complemented with spectroscopic and infrared photometric data from the literature. Two of these turned out to be hot emission-line stars, of which one is a definite B[e] star. The mass-loss rates were measured through modelling of the spectral energy distributions. We thus obtain the mass-loss rate formula log Mdot = -5.65 + 1.05 log(L / 10,000 Lsun) -6.3 log(Teff / 3500 K), valid for dust-enshrouded red supergiants and oxygen-rich AGB stars. Despite the low metallicity of the LMC, both AGB stars and red supergiants are found at late spectral types. A comparison with galactic AGB stars and red supergiants shows excellent agreement between the mass-loss rate as predicted by our formula an...

  3. The nature of B supergiants: clues from a steep drop in rotation rates at 22 000 K. The possibility of bi-stability braking

    NARCIS (Netherlands)

    J.S. Vink; I. Brott; G. Gräfener; N. Langer; A. de Koter; D.J. Lennon

    2010-01-01

    The location of B supergiants in the Hertzsprung-Russell diagram (HRD) represents a long-standing problem in massive star evolution. Here we propose their nature may be revealed utilising their rotational properties, and we highlight a steep drop in massive star rotation rates at an effective temper

  4. Chronic GvHD decreases antiviral immune responses in allogeneic BMT

    OpenAIRE

    Hossain, Mohammad S.; Roback, John D.; Pollack, Brian P.; Jaye, David L.; Langston, Amelia; Waller, Edmund K.

    2007-01-01

    Chronic graft-versus-host disease (cGvHD) is associated with functional immunodeficiency and an increased risk of opportunistic infections in allogeneic bone marrow transplantation (BMT). We used a parent to F1 model of allogeneic BMT to test the hypothesis that cGvHD leads to impaired antigen-specific antiviral immunity and compared BM transplant recipients with cGvHD to control groups of allogeneic BM transplant recipients without GvHD. Mice with and without cGvHD received a nonlethal dose ...

  5. Inhomogeneous molecular ring around the B[e] supergiant LHA 120-S 73

    Science.gov (United States)

    Kraus, M.; Cidale, L. S.; Arias, M. L.; Maravelias, G.; Nickeler, D. H.; Torres, A. F.; Borges Fernandes, M.; Aret, A.; Curé, M.; Vallverdú, R.; Barbá, R. H.

    2016-10-01

    Context. B[e] supergiants are evolved massive stars, enshrouded in a dense wind and surrounded by a molecular and dusty disk. The mechanisms that drive phases of enhanced mass loss and mass ejections, responsible for the shaping of the circumstellar material of these objects, are still unclear. Aims: We aim to improve our knowledge on the structure and dynamics of the circumstellar disk of the Large Magellanic Cloud B[e] supergiant LHA 120-S 73. Methods: High-resolution optical and near-infrared spectroscopic data were obtained over a period of 16 and 7 yr, respectively. The spectra cover the diagnostic emission lines from [Ca ii] and [O i], as well as the CO bands. These features trace the disk at different distances from the star. We analyzed the kinematics of the individual emission regions by modeling their emission profiles. A low-resolution mid-infrared spectrum was obtained as well, which provides information on the composition of the dusty disk. Results: All diagnostic emission features display double-peaked line profiles, which we interpret as due to Keplerian rotation. We find that the profile of each forbidden line contains contributions from two spatially clearly distinct rings. In total, we find that LHA 120-S 73 is surrounded by at least four individual rings of material with alternating densities (or by a disk with strongly non-monotonic radial density distribution). Moreover, we find that the molecular ring must have gaps or at least strong density inhomogeneities, or in other words, a clumpy structure. The optical spectra additionally display a broad emission feature at 6160-6180 Å, which we interpret as molecular emission from TiO. The mid-infrared spectrum displays features of oxygen- and carbon-rich grain species, which indicates a long-lived, stable dusty disk. We cannot confirm the previously reported high value for the stellar rotation velocity. He i λ 5876 is the only clearly detectable pure atmospheric absorption line in our data. Its

  6. Source characterization of AE waves during fatigue crack propagation by joint-frequency analysis method

    International Nuclear Information System (INIS)

    The application of signal processing technique to nondestructive evaluation(NDE) has proven successful for years. In particular the time-frequency such as STFT(Short Time Fourier Transform) and WVD(Wigner-Ville Distribution) has been used to enhance the signal detection in presence of background noise. We will investigate the signal detection in AE during the fatigue test. As a result of time-frequency analysis, we can extract the AE from the raw signal and analyze the frequencies in AE signal at the same time.

  7. 19 CFR 192.13 - Revocation of participants' AES post-departure (Option 4) filing privileges; appeal procedures.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Revocation of participants' AES post-departure... Filing of Export Information Through the Automated Export System (AES) § 192.13 Revocation of participants' AES post-departure (Option 4) filing privileges; appeal procedures. (a) Reasons for...

  8. Detection of multiple AE signal by triaxial hodogram analysis; Sanjiku hodogram ho ni yoru taju acoustic emission no kenshutsu

    Energy Technology Data Exchange (ETDEWEB)

    Nagano, K.; Yamashita, T. [Muroran Institute of Technology, Hokkaido (Japan)

    1997-05-27

    In order to evaluate dynamic behavior of underground cracks, analysis and detection were attempted on multiple acoustic emission (AE) events. The multiple AE is a phenomenon in which multiple AE signals generated by underground cracks developed in an extremely short time interval are superimposed, and observed as one AE event. The multiple AE signal consists of two AE signals, whereas the second P-wave is supposed to have been inputted before the first S-wave is inputted. The first P-wave is inputted first, where linear three-dimensional particle movements are observed, but the movements are made random due to scattering and sensor characteristics. When the second P-wave is inputted, the linear particle movements are observed again, but are superimposed with the existing input signals and become multiple AE, which creates poor S/N ratio. The multiple AE detection determines it a multiple AE event when three conditions are met, i. e. a condition of equivalent time interval of a maximum value in a scalogram analysis, a condition of P-wave vibrating direction, and a condition of the linear particle movement. Seventy AE signals observed in the Kakkonda geothermal field were analyzed and AE signals that satisfy the multiple AE were detected. However, further development is required on an analysis method with high resolution for the time. 4 refs., 4 figs.

  9. FC-AE-1553总线数据处理技术研究%Investigation of FC-AE-1553 Data Processing Technology

    Institute of Scientific and Technical Information of China (English)

    杨现萍; 段亚

    2011-01-01

    With the development of avionics and the improvement of integration technology, MIL-STD-I553 bus's transmission velocity, bandwidth, quantity of allowed terminals and real-time ability have appeared inadequate. Therefore, FC-AE-1553 bus was introduced to overcome the bottleneck caused by MIL-STD-1553. In comparison with the network structure and message configurations of MIL-STD-1553, it is found that FC-AE-1553 bus is much better than MIL-STD-1553 bus in the aspect of performance. The data processing method of FC-AE-1553 is proposed in combination with MIL-STD-1553 bus data processing experience.%随着航空电子技术的发展及综合化程度的提高,MIL-STD-1553总线在传输速率、带宽、允许终端数、实时性等方面开始显得力不从心,为了解决MIL-STD-1553所面临的瓶颈问题,引入FC-AE-1553总线并与MIL-STD-1553比较网络结构与信息构成,经比较得出FC-AE-1553在性能上比MIL-STD-1553更优.结合MIL-STD-1553总线数据处理的工程经验提出FC-AE-1553协议的数据处理方法.

  10. CHEMICAL ABUNDANCES OF THE MAGNETIC CP STAR HD 168733

    Directory of Open Access Journals (Sweden)

    Ana Collado

    2009-01-01

    Full Text Available Se ha llevado a cabo un an lisis detallado de las abundancias en la estrella CP magn tica HD 168733 utilizando espectros de alta resoluci n obtenidos con el espectr grafo echelle EBASIM del telescopio de 2.1 m de CASLEO en Argentina. Los espectros cubren la regi n 382{700 nm. La estrella no puede ser clasi cada ni como una peculiar de HgMn ni como perteneciente al grupo CP2 de silicio. Comparada con el Sol, C, N son levementes sobreabundantes mientras que el Mg y S son de cientes, Si es normal y P y Cl son sobreabundantes. Los elementos del pico de hierro: Sc, Ti, Cr y Fe son sobreabundantes. Se han identi cado tambi n l neas de Ti III y Fe III. HD 168733 muestra una gran sobreabundancia de Ga, Sr, Y, Zr, Xe, Pt, Hg y algunas tierras raras.

  11. Developmentof the 15 T Nb3Sn dipole HD2

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Cheng, D.W.; Dietderich, D.R.; Hafalia, A.R.; Hannaford, C.R.; Higley, H.; Lietzke, A.F.; Lizarazo, J.; McInturff, A.D.; Sabbi, G.; Ferracin, P.

    2008-06-01

    The Superconducting Magnet Program at Lawrence Berkeley National Laboratory (LBNL) is continuing the development of HD2, a 1 m long Nb{sub 3}Sn dipole generating a dipole field of 15 T in a 36 mm clear bore. With tilted (flared) ends to avoid obstructing the beam path, HD2 represents a step towards the development of cost effective accelerator quality magnets. The design has been optimized to minimize geometric harmonics and to address iron saturation and conductor magnetization effects. The support structure is based on an external aluminum shell, pre-tensioned with pressurized bladders and interference keys. Aluminum axial rods and stainless steel end plates provide longitudinal support to the coil ends during magnet excitation. This paper reports on field quality optimization and magnet parameters. The design and fabrication of the coil and structure components, and results from coil winding, reaction, and potting are also presented.

  12. Three-dimensional orbit and physical parameters of HD 6840

    International Nuclear Information System (INIS)

    HD 6840 is a double-lined visual binary with an orbital period of ∼7.5 years. By fitting the speckle interferometric measurements made by the 6 m BTA telescope and 3.5 m WIYN telescope, Balega et al. gave a preliminary astrometric orbital solution of the system in 2006. Recently, Griffin derived a precise spectroscopic orbital solution from radial velocities observed with OPH and Cambridge Coravel. However, due to the low precision of the determined orbital inclination, the derived component masses are not satisfying. By adding the newly collected astrometric data in the Fourth Catalog of Interferometric Measurements of Binary Stars, we give a three-dimensional orbit solution with high precision and derive the preliminary physical parameters of HD 6840 via a simultaneous fit including both astrometric and radial velocity measurements. (paper)

  13. Chemical Abundances of the magnetic CP star HD 168733

    Science.gov (United States)

    Collado, A.; López-García, Z.

    2009-04-01

    A detailed abundance analysis has been carried out for the magnetic CP star HD 168733 using high-resolution spectra obtained with the EBASIM echelle spectrograph at the 2.1 m CASLEO telescope in Argentina. The spectral coverage is 382-700 nm. It is neither a silicon nor a mercury-manganese star. Compared to the Sun, C and N are slightly overabundant, while Mg and S are deficient, Si is normal and P and Cl are overabundant. The iron peak elements Sc, Ti, Cr and Fe are overabundant. Lines of Ti III and Fe III are also identified. HD 168733 shows a great overabundance of Ga, Sr, Y, Zr, Xe, Pt, Hg and of some rare earths.

  14. Kepler Observations of the Asteroseismic Binary HD 176465

    CERN Document Server

    White, T R; Aguirre, V Silva; Ball, W H; Bedding, T R; Chaplin, W J; Christensen-Dalsgaard, J; Garcia, R A; Gizon, L; Stello, D; Aigrain, S; Antia, H M; Appourchaux, T; Bazot, M; Campante, T L; Creevey, O L; Davies, G R; Elsworth, Y P; Gaulme, P; Handberg, R; Hekker, S; Houdek, G; Howe, R; Huber, D; Karoff, C; Marques, J P; Mathur, S; McQuillan, A; Metcalfe, T S; Mosser, B; Nielsen, M B; Régulo, C; Salabert, D; Stahn, T

    2016-01-01

    Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0$\\pm$0.5 Gyr old. The two components of HD 176465 are young phy...

  15. HD 98618: A Star Closely Resembling our Sun

    CERN Document Server

    Melendez, J; Robles, J A; Dodds-Eden, Katie; Melendez, Jorge; Observatory, RSAA/Mt Stromlo

    2006-01-01

    Despite the observational effort carried out in the last few decades, no perfect solar twin has been found to date. An important milestone was achieved a decade ago by Porto de Mello & da Silva, who showed that 18 Sco is almost a solar twin. In the present work, we use extremely high resolution (R = 10^5) high S/N Keck HIRES spectra to carry out a differential analysis of sixteen solar twin candidates. We show that HD 98618 is the second closest solar twin, and that the fundamental parameters of both HD 98618 and 18 Sco are very similar (within a few percent) to the host star of our solar system, including the likelihood of hosting a terrestrial planet within their habitable zone. We suggest that these stars should be given top priority in exoplanet and SETI surveys.

  16. A study on AE monitoring technique for pipelines in electric power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Min Hwa; Cho, Yong Sang; Lee, Sang Guk [Nuclear Power Plant ISI ResearchTeam, Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    1995-11-15

    Acoustic emission monitoring technique of structures and facilities, which is a nondestructive testing method performed under loading, has many advantages of detecting and evaluating discontinuities throughout an large structure during a single test, continuous on-line monitoring, etc. Also this research was focused to develop AE monitoring technique or pipelines in electric power plants and improve safety control capability. As s results, it has been carried out to establish acoustic emission testing for integrity monitoring in pipelines of power plants. It contains that inspection for pipeline layout of plane, studying of AE characteristics for pipeline materials, leak detection technique and its field application. Also, AE testing method was established for leak and defect detection in pipelines and it supplies the AE testing guide for field application.

  17. A study on AE monitoring technique for pipelines in electric power plants

    International Nuclear Information System (INIS)

    Acoustic emission monitoring technique of structures and facilities, which is a nondestructive testing method performed under loading, has many advantages of detecting and evaluating discontinuities throughout an large structure during a single test, continuous on-line monitoring, etc. Also this research was focused to develop AE monitoring technique or pipelines in electric power plants and improve safety control capability. As s results, it has been carried out to establish acoustic emission testing for integrity monitoring in pipelines of power plants. It contains that inspection for pipeline layout of plane, studying of AE characteristics for pipeline materials, leak detection technique and its field application. Also, AE testing method was established for leak and defect detection in pipelines and it supplies the AE testing guide for field application.

  18. Auroral Electrojet (AE, AL, AO, AU) - A Global Measure of Auroral Zone Magnetic Activity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The AE index is derived from geomagnetic variations in the horizontal component observed at selected (10-13) observatories along the auroral zone in the northern...

  19. ?Smart COPVs? - Continued Successful Development of JSC IR&D Acoustic Emissions (AE) SHM Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop and apply promising quantitative pass/fail criteria to CPV using acoustic emission (AE) and lay the foundation for continued development of an automated...

  20. AD/HD and autism spectrum disorders in adults

    OpenAIRE

    Hofvander, Björn

    2009-01-01

    Background: Attention deficit/hyperactivity disorder (AD/HD) and autism spectrum disorders (ASDs) are early-onset, but often life-time impairing, neurodevelopmental disorders. They are highly overlapping and seem to carry considerable risks of negative outcomes, psychiatrically and psychosocially. Childhood hyperactivity is a known risk factor for early-onset conduct disorder (CD), but details concerning the associations between neurodevelopmental problems, aggression, and antisocial personal...

  1. Photometry of the extreme helium star HD 124448

    International Nuclear Information System (INIS)

    The extreme helium star HD 124448 has been examined for photometric variability on time-scales ranging from hours to years. There is no evidence for light variations of more than 0.02 mag. Following a similar result for BD + 1002179, the criterion for pulsational instability in hot luminous hydrogen-deficient stars appears to be the luminosity to mass ratio of the star. (author)

  2. Photometry of the extreme helium star HD 124448

    Energy Technology Data Exchange (ETDEWEB)

    Jeffery, C.S.; Lynas-Gray, A.E. (Saint Andrews Univ. (UK). Observatory)

    1990-01-01

    The extreme helium star HD 124448 has been examined for photometric variability on time-scales ranging from hours to years. There is no evidence for light variations of more than 0.02 mag. Following a similar result for BD + 10{sup 0}2179, the criterion for pulsational instability in hot luminous hydrogen-deficient stars appears to be the luminosity to mass ratio of the star. (author).

  3. On the variability of HD 170699 - a possible COROT target

    CERN Document Server

    Alvarez, M; Parrao, L; Pena, J H; Machado, L Fox; Poretti, E; Martin-Ruiz, S; Amado, P; Garrido, R; Aerts, C; Csurby, Z; Paparo, M

    2008-01-01

    We present the analysis of the variability of HD 170699, a COROT star showing the characteristics of a non evolutionary Delta Scuti star with high rotational velocity. There is a clear period of 10.45 c/d with 5.29 mmag amplitude in the y filter. From the data, it can be seen that the star shows multi-periodicity and it is necessary to add more frequencies to adjust the observations

  4. Searching for stable orbits in the HD 10180 planetary system

    Directory of Open Access Journals (Sweden)

    Laskar J.

    2011-02-01

    Full Text Available A planetary system with at least seven planets has been found around the star HD 10180. However, the traditional Keplerian and n-body fits to the data provide an orbital solution that becomes unstable very quickly, which may quest the reliability of the observations. Here we show that stable orbital configurations can be obtained if general relativity and long-term dissipation raised by tides on the innermost planet are taken into account.

  5. Line Identification of the Si Star HD 87240

    Directory of Open Access Journals (Sweden)

    C. Saffe

    2004-01-01

    Full Text Available Se presentan las identificaciones de las líneas de la estrella peculiar tipo Ap Si HD 87240 (_ = - 59_ 51` 00:1`` en el intervalo espectral 3710{5520. Este objeto es miembro del cúmulo abierto meridional NGC 3114. La comparación de este objeto con otras estrellas Ap Si del campo muestra que tienen en común muchas de las anomalías en sus líneas.

  6. El medio interestelar alrededor de estrellas Of: HD 108

    Science.gov (United States)

    Cappa, C.; Testori, J. C.

    Hemos analizado la distribución del hidrógeno neutro interestelar en la vecindad de la estrella Of HD 108 en base a perfiles de la línea de 21 cm. Estos datos nos han permitido encontrar una probable burbuja interestelar asociada a la estrella. Comparamos estos resultados con la emisión en otros rangos espectrales y estimamos los principales parámetros físicos de la estructura.

  7. Robust statistical properties of the size of large burst events in AE

    OpenAIRE

    Hush, P.; Chapman, S. C.; Dunlop, M. W.; N. W. Watkins

    2015-01-01

    Geomagnetic indices provide a comprehensive data set with which to quantify space climate, that is, how the statistical likelihood of activity varies with the solar cycle. We characterize space climate by the AE index burst distribution. Burst sizes are constructed by thresholding the AE time series; a burst is the sum of the excess in the time series for each time interval over which the threshold is exceeded. The distribution of burst sizes is two component with a crossover in behavior at t...

  8. Validation and empirical correction of MODIS AOT and AE over ocean

    OpenAIRE

    N. A. J. Schutgens; Nakata, M; Nakajima, T.

    2013-01-01

    We present a validation study of Collection 5 MODIS level 2 Aqua and Terra AOT (aerosol optical thickness) and AE (Ångström exponent) over ocean by comparison to coastal and island AERONET (AErosol RObotic NETwork) sites for the years 2003–2009. We show that MODIS (MODerate-resolution Imaging Spectroradiometer) AOT exhibits significant biases due to wind speed and cloudiness of the observed scene, while MODIS AE, although overall unbiased, exhibits less spatial contrast on global scales than ...

  9. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights

    OpenAIRE

    Järvinen, S. P.; Carroll, T. A.; Hubrig, S.; Schöller, M; Ilyin, I; Korhonen, H.; Pogodin, M.; Drake, N.A

    2015-01-01

    Several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be promising for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundan...

  10. Validation and empirical correction of MODIS AOT and AE over ocean

    Directory of Open Access Journals (Sweden)

    N. A. J. Schutgens

    2013-09-01

    Full Text Available We present a validation study of Collection 5 MODIS level 2 Aqua and Terra AOT (aerosol optical thickness and AE (Ångström exponent over ocean by comparison to coastal and island AERONET (AErosol RObotic NETwork sites for the years 2003–2009. We show that MODIS (MODerate-resolution Imaging Spectroradiometer AOT exhibits significant biases due to wind speed and cloudiness of the observed scene, while MODIS AE, although overall unbiased, exhibits less spatial contrast on global scales than the AERONET observations. The same behaviour can be seen when MODIS AOT is compared against Maritime Aerosol Network (MAN data, suggesting that the spatial coverage of our datasets does not preclude global conclusions. Thus, we develop empirical correction formulae for MODIS AOT and AE that significantly improve agreement of MODIS and AERONET observations. We show these correction formulae to be robust. Finally, we study random errors in the corrected MODIS AOT and AE and show that they mainly depend on AOT itself, although small contributions are present due to wind speed and cloud fraction in AOT random errors and due to AE and cloud fraction in AE random errors. Our analysis yields significantly higher random AOT errors than the official MODIS error estimate (0.03 + 0.05 τ, while random AE errors are smaller than might be expected. This new dataset of bias-corrected MODIS AOT and AE over ocean is intended for aerosol model validation and assimilation studies, but also has consequences as a stand-alone observational product. For instance, the corrected dataset suggests that much less fine mode aerosol is transported across the Pacific and Atlantic oceans.

  11. Estimation of Al, Hf, Ta in 247Cm-alloy by ICP-AES

    International Nuclear Information System (INIS)

    The present paper discusses a new method developed for analysis of Al, Hf and Ta in Nickel based 247Cm super alloy by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The procedure employs the dissolution of alloy in a mixture of Sulphuric acid, Nitric acid and Hf and subsequent analysis by sequential ICP-AES (Model JY Ultima 2C HR, France). A Relative Standard Deviation of less than ± 5% has been achieved for all the elements. (author)

  12. HD Photo: a new image coding technology for digital photography

    Science.gov (United States)

    Srinivasan, Sridhar; Tu, Chengjie; Regunathan, Shankar L.; Sullivan, Gary J.

    2007-09-01

    This paper introduces the HD Photo coding technology developed by Microsoft Corporation. The storage format for this technology is now under consideration in the ITU-T/ISO/IEC JPEG committee as a candidate for standardization under the name JPEG XR. The technology was developed to address end-to-end digital imaging application requirements, particularly including the needs of digital photography. HD Photo includes features such as good compression capability, high dynamic range support, high image quality capability, lossless coding support, full-format 4:4:4 color sampling, simple thumbnail extraction, embedded bitstream scalability of resolution and fidelity, and degradation-free compressed domain support of key manipulations such as cropping, flipping and rotation. HD Photo has been designed to optimize image quality and compression efficiency while also enabling low-complexity encoding and decoding implementations. To ensure low complexity for implementations, the design features have been incorporated in a way that not only minimizes the computational requirements of the individual components (including consideration of such aspects as memory footprint, cache effects, and parallelization opportunities) but results in a self-consistent design that maximizes the commonality of functional processing components.

  13. Spatially resolved eastward winds and rotation of HD$\\,$189733b

    CERN Document Server

    Louden, Tom

    2015-01-01

    We measure wind velocities on opposite sides of the hot Jupiter HD$\\,$189733b by modeling sodium absorption in high-resolution HARPS transmission spectra. Our model implicitly accounts for the Rossiter-McLaughlin effect, which we show can explain the high wind velocities suggested by previous studies. Our results reveal a strong eastward motion of the atmosphere of HD$\\,$189733b, with a redshift of $2.3^{+1.3}_{-1.5}\\,$km$\\,$s$^{-1}$ on the leading limb of the planet and a blueshift of $5.3^{+1.0}_{-1.4}\\,$km$\\,$s$^{-1}$ on the trailing limb. These velocities can be understood as a combination of tidally locked planetary rotation and an eastward equatorial jet; closely matching the predictions of atmospheric circulation models. Our results show that the sodium absorption of HD$\\,$189733b is intrinsically velocity broadened and so previous studies of the average transmission spectrum are likely to have overestimated the role of pressure broadening.

  14. The dust, planetesimals and planets of HD 38529

    CERN Document Server

    Moro-Martin, Amaya; Carpenter, John M; Hillenbrand, Lynne A; Wolf, Sebastian; Meyer, Michael R; Hollenbach, David J; Najita, Joan; Henning, Thomas

    2007-01-01

    HD 38529 is a post-main sequence G8III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having Msin(i) of 0.8 MJup and 12.2 MJup, semimajor axes of 0.13 AU and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 micron of 4.7, a small excess at 33 micron (S/N=2.6) and no excess <30 micron. We discuss the distribution of the potential dust-producing planetesimals from the study of the dynamical perturbations of the two known planets, considering in particular the effect of secular resonances. We identify three dynamically stable niches at 0.4-0.8 AU, 20-50 AU and beyond 60 AU. We model the spectral energy distribution of HD 38529 to find out which of these niches show signs of harboring dust-producing plantesimals. The secular analysis, together with the SED modeling resuls, suggest that the planetesimals responsible for most of the du...

  15. Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

    Institute of Scientific and Technical Information of China (English)

    姜忠良; 陈秀云; 陈晓东; 石大立; 杨昌平; 朱静

    2002-01-01

    The effect of Hydrogen Decrepitation (HD) process on the magnetic properties and microstructure of sintered NdFeAlB magnet (HD magnet) was investigated. The results show that the coercivity of HD magnet is higher than that of traditional ball milling (BM) magnet, while the remanence and the maximum energy product of HD magnet are lower. Microstructure analysis shows that some fine un-sintered powders are distributed at the grain boundaries of HD magnet. X-ray diffraction (XRD) analysis reveals that the degree of easy axis alignment of HD magnet is lower. Some ideas to improve the current HD process were proposed.

  16. Temperature, gravity, and bolometric correction scales for non-supergiant OB stars

    Science.gov (United States)

    Nieva, M.-F.

    2013-02-01

    , and in extreme cases, + 6000 K and ± 0.4 dex, respectively. A parameter calibration for sub-spectral types is also proposed. Moreover, we present a new bolometric correction relation to temperature based on our empirical data, rather than on synthetic grids. Conclusions: The photometric calibrations presented here are useful tools to estimate effective temperatures and surface gravities of non-supergiant OB stars in a fast manner. This is also applicable to some single-line spectroscopic binaries, but caution has to be taken for undetected double-lined spectroscopic binaries and single objects with anomalous reddening-law, dubious photometric quantities and/or luminosity classes, for which the systematic uncertainties may increase significantly. We recommend to use these calibrations only as a first step of the parameter estimation, with subsequent refinements based on spectroscopy. A larger sample covering more uniformly the parameter space under consideration will allow refinements to the present calibrations. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max- Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), proposals H2001-2.2-011 and H2005-2.2-016.Based on observations collected at the European Southern Observatory, Chile, ESO 074.B-0455(A) and from the ESO Archive.Based on spectral data retrieved from the ELODIE archive at Observatoire de Haute-Provence (OHP).Appendices A and B are available in electronic form at http://www.aanda.org

  17. AE Geomagnetic Index Predictability for High Speed Solar Wind Streams: A Wavelet Decomposition Technique

    Science.gov (United States)

    Guarnieri, Fernando L.; Tsurutani, Bruce T.; Hajra, Rajkumar; Echer, Ezequiel; Gonzalez, Walter D.; Mannucci, Anthony J.

    2014-01-01

    High speed solar wind streams cause geomagnetic activity at Earth. In this study we have applied a wavelet interactive filtering and reconstruction technique on the solar wind magnetic field components and AE index series to allowed us to investigate the relationship between the two. The IMF Bz component was found as the most significant solar wind parameter responsible by the control of the AE activity. Assuming magnetic reconnection associated to southward directed Bz is the main mechanism transferring energy into the magnetosphere, we adjust parameters to forecast the AE index. The adjusted routine is able to forecast AE, based only on the Bz measured at the L1 Lagrangian point. This gives a prediction approximately 30-70 minutes in advance of the actual geomagnetic activity. The correlation coefficient between the observed AE data and the forecasted series reached values higher than 0.90. In some cases the forecast reproduced particularities observed in the signal very well.The high correlation values observed and the high efficacy of the forecasting can be taken as a confirmation that reconnection is the main physical mechanism responsible for the energy transfer during HILDCAAs. The study also shows that the IMF Bz component low frequencies are most important for AE prediction.

  18. Incorporation of Wave Pipelined Techniques into Composite S-Box and AES Architectures

    Directory of Open Access Journals (Sweden)

    M. Senthil Kumar

    2014-10-01

    Full Text Available Advanced Encryption Standard is one of the most successful techniques used in various security applications. The AES technique is known to provide reliable security standards, which is why it is preferred over many other methods. The AES architecture consists of S-Box, Shift-Rows, Mix-Columns and Add Round key. Improving the S-Box structure using pipelining improves the speed of operations along with the security. The main aim of this research study is to design a modified composite S-Box for low area, power and high Speed with high security for application in AES process. In this study, we propose a WPT in S-Box also controlling the registers with a clock-gate structure, to further reduce the operational delay and obtain high security. The modified S-Box is then included in the AES architecture with an additional modification on the overall AES architecture by introducing the WPT in every round of AES operation. This is not only improves the speed of operation and also it provides high security compared to many existing techniques along with the area and power reduction. Simulations have been performed in the ModelSim6.3c and Synthesis is carried out using Xilinx10.1.

  19. Abundances of the heavy elements in the Magellanic Clouds. I. Metal abundances of F-type supergiants

    International Nuclear Information System (INIS)

    Metal abundances of eight F-type supergiants in each of the Magellanic Clouds were determined using the results of high-resolution spectroscopy analysis of these stars, together with new Stromgren uvby and Cousins (1980) BVRI photometry. It was found that the mean Fe abundance (Fe/H) for the SMC is -0.65 + or - 0.2 dex, and the mean Fe abundance for the LMC is -0.30 + or - 0.2 dex. The abundances of stars in both the SMC and LMC appear relatively uniform, and the abundances of the elements relative to Fe are very similar in both Magellanic Clouds and in Canopus (the carbon-to-iron abundances are the same for all three). It was also found that Nd and Sm are overabundant in both clouds, supporting the trends found by Spite et al. (1988) for the three SMC stars they studied. 140 refs

  20. 2D radiaition-hydrodynamic simulations of supernova shock breakout in bipolar explosions of a blue supergiant progenitor

    CERN Document Server

    Suzuki, Akihiro; Shigeyama, Toshikazu

    2016-01-01

    A two-dimensional special relativistic radiation-hydrodynamics code is developed and applied to numerical simulations of supernova shock breakout in bipolar explosions of a blue supergiant. Our calculations successfully simulate the dynamical evolution of a blast wave in the star and its emergence from the surface. Results of the model with spherical energy deposition show a good agreement with previous simulations. Furthermore, we calculate several models with bipolar energy deposition and compare their results with the spherically symmetric model. The bolometric light curves of the shock breakout emission are calculated by a ray-tracing method. Our radiation-hydrodynamic models indicate that the early part of the shock breakout emission can be used to probe the geometry of the blast wave produced as a result of the gravitational collapse of the iron core.