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Sample records for super-asymptotic giant branch

  1. On Carbon Burning in Super Asymptotic Giant Branch Stars

    CERN Document Server

    Farmer, R; Timmes, F X

    2015-01-01

    We explore the detailed and broad properties of carbon burning in Super Asymptotic Giant Branch (SAGB) stars with 2755 MESA stellar evolution models. The location of first carbon ignition, quenching location of the carbon burning flames and flashes, angular frequency of the carbon core, and carbon core mass are studied as a function of the ZAMS mass, initial rotation rate, and mixing parameters such as convective overshoot, semiconvection, thermohaline and angular momentum transport. In general terms, we find these properties of carbon burning in SAGB models are not a strong function of the initial rotation profile, but are a sensitive function of the overshoot parameter. We quasi-analytically derive an approximate ignition density, $\\rho_{ign} \\approx 2.1 \\times 10^6$ g cm$^{-3}$, to predict the location of first carbon ignition in models that ignite carbon off-center. We also find that overshoot moves the ZAMS mass boundaries where off-center carbon ignition occurs at a nearly uniform rate of $\\Delta M_{\\rm...

  2. Cyanogen in NGC 1851 Red Giant Branch and Asymptotic Giant Branch Stars: Quadrimodal Distributions

    DEFF Research Database (Denmark)

    Campbell, S. W.; Yong, D.; Wylie-de Boer, E. C.

    2012-01-01

    The Galactic globular cluster NGC 1851 has raised much interest since Hubble Space Telescope photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) band strengths in the red giant branch (RGB) population (17 stars) and asymptotic...

  3. Cyanogen in NGC 1851 Red Giant Branch and Asymptotic Giant Branch Stars: Quadrimodal Distributions

    DEFF Research Database (Denmark)

    Campbell, S. W.; Yong, D.; Wylie-de Boer, E. C.;

    2012-01-01

    The Galactic globular cluster NGC 1851 has raised much interest since Hubble Space Telescope photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) band strengths in the red giant branch (RGB) population (17 stars) and asymptotic...

  4. Introduction to Asymptotic Giant Branch Stars

    Science.gov (United States)

    El Eid, Mounib F.

    2016-04-01

    A brief introduction on the main characteristics of the asymptotic giant branch stars (briefly: AGB) is presented. We describe a link to observations and outline basic features of theoretical modeling of these important evolutionary phases of stars. The most important aspects of the AGB stars is not only because they are the progenitors of white dwarfs, but also they represent the site of almost half of the heavy element formation beyond iron in the galaxy. These elements and their isotopes are produced by the s-process nucleosynthesis, which is a neutron capture process competing with the β- radioactive decay. The neutron source is mainly due to the reaction 13C(α,n)16O reaction. It is still a challenging problem to obtain the right amount of 13 C that can lead to s-process abundances compatible with observation. Some ideas are presented in this context.

  5. On the red giant branch mass loss in 47 Tucanae: Constraints from the horizontal branch morphology

    CERN Document Server

    Salaris, Maurizio; Pietrinferni, Adriano

    2016-01-01

    We obtain stringent constraints on the actual efficiency of mass loss for red giant branch stars in the Galactic globular cluster 47 Tuc, by comparing synthetic modeling based on stellar evolution tracks with the observed distribution of stars along the horizontal branch in the colour-magnitude-diagram. We confirm that the observed, wedge-shaped distribution of the horizontal branch can be reproduced only by accounting for a range of initial He abundances --in agreement with inferences from the analysis of the main sequence-- and a red giant branch mass loss with a small dispersion. We have carefully investigated several possible sources of uncertainty that could affect the results of the horizontal branch modeling, stemming from uncertainties in both stellar model computations and the cluster properties such as heavy element abundances, reddening and age. We determine a firm lower limit of ~0.17$Mo for the mass lost by red giant branch stars, corresponding to horizontal branch stellar masses between ~0.65Mo ...

  6. The Red Giant Branch in the Tycho-2 Catalogue

    CERN Document Server

    Gontcharov, George

    2016-01-01

    Based on multicolor photometry from the 2MASS and Tycho-2 catalogues, we have produced a sample of 38 368 branch red giants that has less than 1\\% of admixtures and is complete within 500 pc of the Sun. The sample includes 30 671 K giants, 7544 M giants, 49 C giants, and 104 suspected supergiants or S stars. The photometric distances have been calculated for K, M, and C stars with an accuracy of 40\\%. Tycho-2 proper motions and PCRV radial velocities are used to analyze the stellar kinematics. The decrease in the stellar distribution density with distance from the Galactic equator approximated by the barometric law, contrary to the Besancon model of the Galaxy, and the kinematic parameters calculated using the Ogorodnikov--Milne model characterize the overwhelming majority of the selected K and M giants as disk stars with ages of more than 3 Gyr. A small number of K and M giants are extremely young or, conversely, thick-disk ones. The latter show a nonuniform distribution in the phase space of coordinates and...

  7. 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.

  8. Chemical analysis of Asymptotic Giant Branch stars in M62

    CERN Document Server

    Lapenna, E; Ferraro, F R; Origlia, L; Lanzoni, B; Massari, D; Dalessandro, E

    2015-01-01

    We have collected UVES-FLAMES high-resolution spectra for a sample of 6 asymptotic giant branch (AGB) and 13 red giant branch (RGB) stars in the Galactic globular cluster M62 (NGC6266). Here we present the detailed abundance analysis of iron, titanium, and light-elements (O, Na, Al and Mg). For the majority (5 out 6) of the AGB targets we find that the abundances, of both iron and titanium, determined from neutral lines are significantly underestimated with respect to those obtained from ionized features, the latter being, instead, in agreement with those measured for the RGB targets. This is similar to recent findings in other clusters and may suggest the presence of Non-Local Thermodynamical Equilibrium (NLTE) effects. In the O-Na, Al-Mg and Na-Al planes, the RGB stars show the typical correlations observed for globular cluster stars. Instead, all the AGB targets are clumped in the regions where first generation stars are expected to lie, similarly to what recently found for the AGB population of NGC6752. W...

  9. The Asymptotic Giant Branch and the Tip of the Red Giant Branch as Probes of Star Formation History: The Nearby Dwarf Irregular Galaxy KKH 98

    OpenAIRE

    Melbourne, J; Williams, B.; Dalcanton, J.; Ammons, S. M.; Max, C.; Koo, D.C.; Girardi, Leo; Dolphin, A.

    2010-01-01

    We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D=2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (IR) Keck Laser Guide Star Adaptive Optics (AO) images resolve 592 IR bright stars reaching over 1 magnitude below the Tip of the Red Giant Branch. Significantly deeper optical (F475W and F814W) Hubble Space Telescope images of the same field contain over 2500 stars, reaching to the ...

  10. CHEMICAL ANALYSIS OF ASYMPTOTIC GIANT BRANCH STARS IN M62

    Energy Technology Data Exchange (ETDEWEB)

    Lapenna, E.; Mucciarelli, A.; Ferraro, F. R.; Lanzoni, B.; Dalessandro, E. [Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Origlia, L.; Massari, D. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani, 1, I-40127 Bologna (Italy)

    2015-11-10

    We have collected UVES-FLAMES high-resolution spectra for a sample of 6 asymptotic giant branch (AGB) and 13 red giant branch (RGB) stars in the Galactic globular cluster (GC) M62 (NGC 6266). Here we present the detailed abundance analysis of iron, titanium, and light elements (O, Na, Mg, and Al). For the majority (five out of six) of the AGB targets, we find that the abundances of both iron and titanium determined from neutral lines are significantly underestimated with respect to those obtained from ionized features, the latter being, instead, in agreement with those measured for the RGB targets. This is similar to recent findings in other clusters and may suggest the presence of nonlocal thermodynamic equilibrium (NLTE) effects. In the O–Na, Al–Mg, and Na–Al planes, the RGB stars show the typical correlations observed for GC stars. Instead, all the AGB targets are clumped in the regions where first-generation stars are expected to lie, similar to what was recently found for the AGB population of NGC 6752. While the sodium and aluminum abundances could be underestimated as a consequence of the NLTE bias affecting iron and titanium, the oxygen line used does not suffer from the same effects, and the lack of O-poor AGB stars therefore is a solid result. We can thus conclude that none of the investigated AGB stars belongs to the second stellar generation of M62. We also find an RGB star with extremely high sodium abundance ([Na/Fe] = +1.08 dex)

  11. Stellar yields from metal-rich asymptotic giant branch models

    CERN Document Server

    Karakas, Amanda I

    2016-01-01

    We present new theoretical stellar yields and surface abundances for three grids of metal-rich asymptotic giant branch (AGB) models. Post-processing nucleosynthesis results are presented for stellar models with initial masses between 1$M_{\\odot}$ and 7.5$M_{\\odot}$ for $Z=0.007$, and 1$M_{\\odot}$ and 8$M_{\\odot}$ for $Z=0.014$ (solar) and $Z=0.03$. We include stellar surface abundances as a function of thermal pulse on the AGB for elements from C to Bi and for a selection of isotopic ratios for elements up to Fe and Ni (e.g., $^{12}$C/$^{13}$C), which can be obtained from observations of molecules in stars and from the laboratory analysis of meteoritic stardust grains. Ratios of elemental abundances of He/H, C/O, and N/O are also included, which are useful for direct comparison to observations of AGB stars and their progeny including planetary nebulae. The integrated elemental stellar yields are presented for each model in the grid for hydrogen, helium and all stable elements from C to Bi. Yields of Li are al...

  12. An HI Imaging Survey of Asymptotic Giant Branch Stars

    CERN Document Server

    Matthews, L D; Gerard, E; Johnson, M C

    2013-01-01

    We present an imaging study of a sample of eight asymptotic giant branch (AGB) stars in the HI 21-cm line. Using observations from the Very Large Array, we have unambiguously detected HI emission associated with the extended circumstellar envelopes of six of the targets. The detected HI masses range from M_HI ~ 0.015-0.055 M_sun. The HI morphologies and kinematics are diverse, but in all cases appear to be significantly influenced by the interaction between the circumstellar envelope and the surrounding medium. Four stars (RX Lep, Y UMa, Y CVn, and V1942 Sgr) are surrounded by detached HI shells ranging from 0.36 to 0.76 pc across. We interpret these shells as resulting from material entrained in a stellar outflow being abruptly slowed at a termination shock where it meets the local medium. RX Lep and TX Psc, two stars with moderately high space velocities (V_space>56 km/s), exhibit extended gaseous wakes (~0.3 and 0.6 pc in the plane of the sky), trailing their motion through space. The other detected star, ...

  13. Stellar Models and Yields of Asymptotic Giant Branch Stars

    CERN Document Server

    Karakas, Amanda I

    2007-01-01

    We present stellar yields calculated from detailed models of low and intermediate-mass asymptotic giant branch (AGB) stars. We evolve models with a range of mass from 1 to 6Msun, and initial metallicities from solar to 1/200th of the solar metallicity. Each model was evolved from the zero age main sequence to near the end of the thermally-pulsing AGB phase, and through all intermediate phases including the core He-flash for stars initially less massive than 2.5Msun. For each mass and metallicity, we provide tables containing structural details of the stellar models during the TP-AGB phase, and tables of the stellar yields for 74 species from hydrogen through to sulphur, and for a small number of iron-group nuclei. All tables are available for download. Our results have many applications including use in population synthesis studies and the chemical evolution of galaxies and stellar systems, and for comparison to the composition of AGB and post-AGB stars and planetary nebulae.

  14. Solar-Like Cycle in Asymptotic Giant Branch Stars

    CERN Document Server

    Soker, N

    2000-01-01

    I propose that the mechanism behind the formation of concentric semi-periodic shells found in several planetary nebulae (PNs) and proto-PNs, and around one asymptotic giant branch (AGB) star, is a solar-like magnetic activity cycle in the progenitor AGB stars. The time intervals between consecutive ejection events is about 200-1,000 years, which is assumed to be the cycle period (the full magnetic cycle can be twice as long, as is the 22-year period in the sun). The magnetic field has no dynamical effects; it regulates the mass loss rate by the formation of magnetic cool spots. The enhanced magnetic activity at the cycle maximum results in more magnetic cool spots, which facilitate the formation of dust, hence increasing the mass loss rate. The strong magnetic activity implies that the AGB star is spun up by a companion, via a tidal or common envelope interaction. The strong interaction with a stellar companion explains the observations that the concentric semi-periodic shells are found mainly in bipolar PNs.

  15. Aluminum 26 production in asymptotic giant branch stars

    Science.gov (United States)

    Mowlavi, N.; Meynet, G.

    2000-09-01

    The production of 26Al in asymptotic giant branch (AGB) stars is studied based on evolutionary stellar models of different masses (1.5 region follows, at a given metallicity, a very well defined pattern as a function of the H-burning shell temperature TH. Two zones must be distinguished. The first one comprises those He-rich layers containing H-burning ashes which escape pulse in jection. The amount of 26Al in that zone (M\\odot1-2×10-7 at the first pulse in M\\odot1.5-3 Z=0.02 stars) steadily decreases with pulse number. Its contribution to the surface 26Al enhancement can only be important during the first pulses if dredge--up occurs at that stage. The second zone consists of the C-rich material emerging from the pulses. The amount of 26Al available in that zone is higher than that in the first zone (M\\odot3-4×10-7 at the first pulse in M\\odot1.5-3 Z=0.02 stars), and keeps constant during about the first dozen pulses before decreasing when TH~> 55× 106 K. This zone is thus an important potential reservoir for surface 26Al enrichment. Using third dredge-up (3DUP) efficiencies from model calculations, the surface 26Al abundance is predicted to reach 1-2× 10-7 mass fractions in our low-mass solar metallicity stars, with an uncertainty factor of about three. It decreases with increasing stellar mass, being about three times lower in a M\\odot4 than in M\\odot2-3 stars. In massive AGB stars, however, hot bottom burning enables to easily reach surface 26Al mass fractions above 10-6. The 26Al/27Al ratios measured in meteoritic SiC and oxide grains are discussed, as well as that possibly measured in the nearby C-star IRC+10216. We also address the contribution of AGB stars to the 2-3 M\\odot present day mass of 26Al detected in the Galaxy. Finally, we discuss the possibility of directly detecting an AGB star or a planetary nebula as a single source at 1.8 MeV with the future INTEGRAL satellite.

  16. Concurrent central retinal artery occlusion and branch retinal vein occlusion in giant cell arteritis

    OpenAIRE

    Chu, Edward R.; Chen, Celia S

    2010-01-01

    Edward R Chu, Celia S ChenDepartment of Ophthalmology, Flinders Medical Centre and Flinders University, Bedford Park, SA, AustraliaAbstract: Ophthalmic involvement in giant cell arteritis can manifest in a number of ways. Central retinal artery occlusion is one of the common causes of visual loss in giant cell arteritis. On the contrary, branch retinal vein occlusion is rarely associated with the latter. We report an 89-year-old lady with acute left central retinal artery occlusion on a backg...

  17. The Asymptotic Giant Branch and the Tip of the Red Giant Branch as Probes of Star Formation History: The Nearby Dwarf Irregular Galaxy KKH 98

    CERN Document Server

    Melbourne, J; Dalcanton, J; Ammons, S M; Max, C; Koo, D C; Girardi, Leo; Dolphin, A

    2010-01-01

    We investigate the utility of the asymptotic giant branch (AGB) and the red giant branch (RGB) as probes of the star formation history (SFH) of the nearby (D=2.5 Mpc) dwarf irregular galaxy, KKH 98. Near-infrared (IR) Keck Laser Guide Star Adaptive Optics (AO) images resolve 592 IR bright stars reaching over 1 magnitude below the Tip of the Red Giant Branch. Significantly deeper optical (F475W and F814W) Hubble Space Telescope images of the same field contain over 2500 stars, reaching to the Red Clump and the Main Sequence turn-off for 0.5 Gyr old populations. Compared to the optical color magnitude diagram (CMD), the near-IR CMD shows significantly tighter AGB sequences, providing a good probe of the intermediate age (0.5 - 5 Gyr) populations. We match observed CMDs with stellar evolution models to recover the SFH of KKH 98. On average, the galaxy has experienced relatively constant low-level star formation (5 x 10^-4 Mo yr^-1) for much of cosmic time. Except for the youngest main sequence populations (age &...

  18. Resolved Stellar Halos of M87 and NGC 5128: Metallicities from the Red-Giant Branch

    Science.gov (United States)

    Bird, Sarah A.

    2016-08-01

    We have searched halo fields of two giant elliptical galaxies: M87, using HST images at 10 kpc from the galactic center, and NGC 5128 (Cen A), using VIMOS VLT images at 65 kpc from the center and archival HST data from 8 to 38 kpc from the center. We have resolved thousands of red-giant-branch (RGB) stars in these stellar halo fields using V and I filters, and, in addition, measured the metallicity using stellar isochrones. The metallicity distribution function (MDF) of the inner stellar halo of M87 is similar to that of NGC 5128's stellar halo.

  19. Multiple populations along the asymptotic giant branch of the globular cluster M4

    Science.gov (United States)

    Lardo, C.; Salaris, M.; Savino, A.; Donati, P.; Stetson, P. B.; Cassisi, S.

    2017-04-01

    Nearly all Galactic globular clusters host stars that display characteristic abundance anticorrelations, like the O-rich/Na-poor pattern typical of field halo stars, together with O-poor/Na-rich additional components. A recent spectroscopic investigation questioned the presence of O-poor/Na-rich stars amongst a sample of asymptotic giant branch (AGB) stars in the cluster M4, at variance with the spectroscopic detection of a O-poor/Na-rich component along both the cluster red giant branch (RGB) and horizontal branch. This is contrary to what is expected from the cluster horizontal branch morphology and horizontal branch stellar evolution models. Here, we have investigated this issue by employing the CUBI = (U - B) - (B - I) index, that previous studies have demonstrated to be very effective in separating multiple populations along both the RGB and AGB sequences. We confirm previous results that the RGB is intrinsically broad in the V-CUBI diagram, with the presence of two components that nicely correspond to the two populations identified by high-resolution spectroscopy. We find that AGB stars are distributed over a wide range of CUBI values, in close analogy with what is observed for the RGB, demonstrating that the AGB of M4 also hosts multiple stellar populations.

  20. Testing the core of red-giant-branch stars using the period spacing of gravity modes

    Science.gov (United States)

    Lagarde, Nadège; Diego, Bossini; Miglio, Andrea

    2015-08-01

    The blooming of asteroseismology of red-giant stars with the CoRoT and Kepler space missions paves the way to a better understanding of the stellar structure and physical processes occurring in low-mass-giant stars.We investigate the effect of rotation on the asymptotic period spacing of gravity modes (DP) and on the coupling strength between acoustic and gravity modes. We focus on red-giant-branch stars (RGB) which ignite He in degenerate conditions (Mstars below the RGB bump, additional transport processes of chemicals have an impact on DP, hence on the determination of the stellar mass when DP is used as a constraint. Moreover we show that the coupling strength gives a direct signature of rotation occuring in red-giant stars. Whether this signature can be inferred from current data needs however to be investigated further. Finally we show that, irrespective of additional transport processes occurring during the main sequence, the period spacing of red-giant stars brighter than the RGB bump is an accurate proxy for the stellar luminosity, due to the well known relation between MHecore and luminosity.

  1. A giant planet orbiting the 'extreme horizontal branch' star V 391 Pegasi.

    Science.gov (United States)

    Silvotti, R; Schuh, S; Janulis, R; Solheim, J-E; Bernabei, S; Østensen, R; Oswalt, T D; Bruni, I; Gualandi, R; Bonanno, A; Vauclair, G; Reed, M; Chen, C-W; Leibowitz, E; Paparo, M; Baran, A; Charpinet, S; Dolez, N; Kawaler, S; Kurtz, D; Moskalik, P; Riddle, R; Zola, S

    2007-09-13

    After the initial discoveries fifteen years ago, over 200 extrasolar planets have now been detected. Most of them orbit main-sequence stars similar to our Sun, although a few planets orbiting red giant stars have been recently found. When the hydrogen in their cores runs out, main-sequence stars undergo an expansion into red-giant stars. This expansion can modify the orbits of planets and can easily reach and engulf the inner planets. The same will happen to the planets of our Solar System in about five billion years and the fate of the Earth is matter of debate. Here we report the discovery of a planetary-mass body (Msini = 3.2M(Jupiter)) orbiting the star V 391 Pegasi at a distance of about 1.7 astronomical units (au), with a period of 3.2 years. This star is on the extreme horizontal branch of the Hertzsprung-Russell diagram, burning helium in its core and pulsating. The maximum radius of the red-giant precursor of V 391 Pegasi may have reached 0.7 au, while the orbital distance of the planet during the stellar main-sequence phase is estimated to be about 1 au. This detection of a planet orbiting a post-red-giant star demonstrates that planets with orbital distances of less than 2 au can survive the red-giant expansion of their parent stars.

  2. On Lithium-rich Red Giants: Engulfment on the Giant Branch of Trumpler 20

    Science.gov (United States)

    Aguilera-Gómez, Claudia; Chanamé, Julio; Pinsonneault, Marc H.; Carlberg, Joleen K.

    2016-12-01

    The Gaia-ESO survey recently reported on a large sample of lithium (Li) abundance determinations for evolved stars in the rich open cluster Trumpler 20. They argue for a scenario where virtually all stars experience post-main-sequence mixing and Li is preserved in only two objects. We present an alternate explanation, where Li is normal in the vast majority of cluster stars and anomalously high in these two cases. We demonstrate that the Li upper limits in the red giants can be explained with a combination of main-sequence depletion and standard dredge-up and that they are close to the detected levels in other systems of similar age. In our framework, two of the detected giants are anomalously Li-rich, and we propose that both could have been produced by the engulfment of a substellar mass companion of {16}-10+6 {M}{{J}}. This would imply that ˜ 5 % of 1.8 {M}⊙ stars in this system, and by extension elsewhere, should have substellar mass companions of high mass that could be engulfed at some point in their lifetimes. We discuss future tests that could confirm or refute this scenario.

  3. On Lithium-Rich Red Giants. II. Engulfment on the Giant Branch of Trumpler 20

    CERN Document Server

    Aguilera-Gómez, Claudia; Pinsonneault, Marc H; Carlberg, Joleen K

    2016-01-01

    The Gaia-ESO survey recently reported on a large sample of lithium (Li) abundance determinations for evolved stars in the rich open cluster Trumpler 20. They argue for a scenario where virtually all stars experience post main sequence mixing and Li is preserved in only two objects. We present an alternate explanation, where Li is normal in the vast majority of cluster stars and anomalously high in these two cases. We demonstrate that the Li upper limits in the red giants can be explained with a combination of main sequence depletion and standard dredge-up, and that they are close to the detected levels in other systems of similar age. In our framework, the two detected giants are anomalously Li-rich, and we propose that both could have been produced by the engulfment of a substellar mass companion of 14+-8M_J. This would imply that ~5% of 1.8 solar mass stars in this system, and by extension elsewhere, should have substellar mass companions of high mass that could be engulfed at some point in their lifetimes....

  4. Dust is forming along the red giant branch of 47 TUC

    CERN Document Server

    Origlia, Livia; Fabbri, Sara; Ferraro, Francesco R; Pecci, Flavio Fusi; Rich, R Michael; Dalessandro, Emanuele

    2010-01-01

    We present additional evidence that dust is really forming along the red giant branch (RGB) of 47 Tuc at luminosities ranging from above the horizontal branch to the RGB-tip (Origlia et al. 2007). The presence of dust had been inferred from an infrared excess in the (K-8) color, with K measured from high spatial resolution ground based near-IR photometry and "8" referring to Spitzer-IRAC 8 micron photometry. We show how (K-8) is a far more sensitive diagnostic for detecting tiny circumstellar envelopes around warm giants than colors using only the Spitzer-IRAC bands, for example the (3.6-8) color used by Boyer et al. (2010). In addition, we also show high resolution HST-ACS I band images of the giant stars which have (K-8) color excess. These images clearly demonstrate that Boyer et al (2010) statement that our detections of color excess associated with stars below the RGB-tip arise from blends and artefacts is simply not valid.

  5. ISOCAM observations of Galactic Globular Clusters mass loss along the Red Giant Branch

    CERN Document Server

    Origlia, L; Pecci, F F; Rood, R T; Origlia, Livia; Ferraro, Francesco R.; Pecci, Flavio Fusi; Rood, Robert T.

    2002-01-01

    Deep images in the 10 micron spectral region have been obtained for five massive Galactic globular clusters, NGC 104 (=47 Tuc), NGC 362, NGC 5139 (omega Cen), NGC 6388, NGC 7078 (=M15) and NGC 6715 (=M54) in the Sagittarius Dwarf Spheroidal using ISOCAM in 1997. A significant sample of bright giants have an ISOCAM counterpart but only < 20% of these have a strong mid-IR excess indicative of dusty circumstellar envelopes. From a combined physical and statistical analysis we derive mass loss rates and frequency. We find that i) significant mass loss occurs only at the very end of the Red Giant Branch evolutionary stage and is episodic, ii) the modulation timescales must be greater than a few decades and less than a million years, and iii) mass loss occurrence does not show a crucial dependence on the cluster metallicity.

  6. Light Element Chemistry and the Double Red Giant Branch in the Galactic Globular Cluster NGC 288

    CERN Document Server

    Hsyu, Tiffany; Lee, Young-Wook; Rich, R Michael

    2014-01-01

    The globular cluster NGC 288 was previously reported to exhibit two distinct red giant branches (RGBs) in the narrow-band Calcium (HK) and Str\\"omgren b and y band passes. In order to investigate this phenomenon further, we obtained moderate resolution (R$\\sim$18,000) spectra of 27 RGB stars in NGC 288 with the Hydra multifiber spectrograph on the Blanco 4m telescope at Cerro Tololo Inter-American Observatory. From these data we derive iron ($\\langle$[Fe/H]$\\rangle$=-1.19; $\\sigma$=0.12), oxygen ($\\langle$[O/Fe]$\\rangle$=$+$0.25; $\\sigma$=0.13), and sodium ($\\langle$[Na/Fe]$\\rangle$=$+$0.15; $\\sigma$=0.26) abundances using standard equivalent width and spectrum synthesis techniques. Combining these data with those available in the literature indicates that the two giant branches have distinctly different light element chemistry but do not exhibit a significant spread in [Fe/H]. A new transmission tracing for the CTIO Ca filter, obtained for this project, shows that CN contamination is the primary spectral fea...

  7. HUBBLE SPACE TELESCOPE REVEALS MULTIPLE SUB-GIANT BRANCH IN EIGHT GLOBULAR CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Piotto, G.; Nascimbeni, V. [Dipartimento di Astronomia, Universita di Padova, Vicolo dell' Osservatorio 3, I-35122 Padova (Italy); Milone, A. P.; Aparicio, A. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife, Canary Islands (Spain); Anderson, J.; Bellini, A. [Space Telescope Science Institute, 3800 San Martin Drive, Baltimore, MD 21218 (United States); Bedin, L. R. [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Cassisi, S. [INAF-Osservatorio Astronomico di Collurania, via Mentore Maggini, I-64100 Teramo (Italy); Marino, A. F., E-mail: giampaolo.piotto@unipd.it, E-mail: luigi.bedin@oapd.inaf.it, E-mail: milone@iac.es, E-mail: aparicio@iac.es, E-mail: jayander@stsci.edu, E-mail: bellini@stsci.edu, E-mail: cassisi@oa-teramo.inaf.it, E-mail: amarino@MPA-Garching.MPG.DE [Max Planck Institute for Astrophysics, Postfach 1317, D-85741 Garching (Germany)

    2012-11-20

    In the last few years many globular clusters (GCs) have revealed complex color-magnitude diagrams, with the presence of multiple main sequences (MSs), broad or multiple sub-giant branches (SGBs) and MS turnoffs, and broad or split red giant branches (RGBs). After a careful correction for differential reddening, high-accuracy photometry with the Hubble Space Telescope (HST) presented in this paper reveals a broadened or even split SGB in five additional Milky Way GCs: NGC 362, NGC 5286, NGC 6656, NGC 6715, and NGC 7089. In addition, we confirm (with new and archival HST data) the presence of a split SGB in 47 Tuc, NGC 1851, and NGC 6388. The fraction of faint SGB stars with respect to the entire SGB population varies from one cluster to another and ranges from {approx}0.03 for NGC 362 to {approx}0.50 for NGC 6715. The average magnitude difference between the bright SGB and the faint SGB is almost the same at different wavelengths. This peculiarity is consistent with the presence of two groups of stars with either an age difference of about 1-2 Gyr or a significant difference in their overall C+N+O content.

  8. Habitability of super-Earth planets around other suns: models including Red Giant Branch evolution.

    Science.gov (United States)

    von Bloh, W; Cuntz, M; Schröder, K-P; Bounama, C; Franck, S

    2009-01-01

    The unexpected diversity of exoplanets includes a growing number of super-Earth planets, i.e., exoplanets with masses of up to several Earth masses and a similar chemical and mineralogical composition as Earth. We present a thermal evolution model for a 10 Earth-mass planet orbiting a star like the Sun. Our model is based on the integrated system approach, which describes the photosynthetic biomass production and takes into account a variety of climatological, biogeochemical, and geodynamical processes. This allows us to identify a so-called photosynthesis-sustaining habitable zone (pHZ), as determined by the limits of biological productivity on the planetary surface. Our model considers solar evolution during the main-sequence stage and along the Red Giant Branch as described by the most recent solar model. We obtain a large set of solutions consistent with the principal possibility of life. The highest likelihood of habitability is found for "water worlds." Only mass-rich water worlds are able to realize pHZ-type habitability beyond the stellar main sequence on the Red Giant Branch.

  9. Abundances of C, N, Sr and Ba on the red giant branch of omega Centauri

    CERN Document Server

    Stanford, Laura M; Norris, John E

    2010-01-01

    Abundances relative to iron for carbon, nitrogen, strontium and barium are presented for 33 stars on the red giant branch of the globular cluster omega Centauri. They are based on intermediate-resolution spectroscopic data covering the blue spectral region analyzed using spectrum synthesis techniques. The data reveal the existence of a broad range in the abundances of these elements, and a comparison with similar data for main sequence stars enables insight into the evolutionary history of the cluster. The majority of the red giant branch stars were found to be depleted in carbon, i.e. [C/Fe]<0, while [N/Fe] for the same stars shows a range of ~1 dex, from [N/Fe]~0.7 to 1.7 dex. The strontium-to-iron abundance ratios varied from solar to mildly enhanced (0.0<=[Sr/Fe]<=0.8), with [Ba/Fe] generally equal to or greater than [Sr/Fe]. The carbon and nitrogen abundance ratios for the one known CH star in the sample, ROA 279, are [C/Fe]=0.6 and [N/Fe]=0.5 dex. Evidence for evolutionary mixing on the red gia...

  10. Chemical abundances in the multiple sub-giant branch of 47 Tucanae: insights on its faint sub-giant branch component

    CERN Document Server

    Marino, A F; Casagrande, L; Collet, R; Dotter, A; Johnson, C I; Lind, K; Bedin, L R; Jerjen, H; Aparicio, A; Sbordone, L

    2016-01-01

    The globular cluster 47 Tuc exhibits a complex sub-giant branch (SGB) with a faint-SGB comprising only about the 10% of the cluster mass and a bright-SGB hosting at least two distinct populations.We present a spectroscopic analysis of 62 SGB stars including 21 faint-SGB stars. We thus provide the first chemical analysis of the intriguing faint-SGB population and compare its abundances with those of the dominant populations. We have inferred abundances of Fe, representative light elements C, N, Na, and Al, {\\alpha} elements Mg and Si for individual stars. Oxygen has been obtained by co-adding spectra of stars on different sequences. In addition, we have analysed 12 stars along the two main RGBs of 47 Tuc. Our principal results are: (i) star-to-star variations in C/N/Na among RGB and bright-SGB stars; (ii) substantial N and Na enhancements for the minor population corresponding to the faint-SGB; (iii) no high enrichment in C+N+O for faint-SGB stars. Specifically, the C+N+O of the faint-SGB is a factor of 1.1 hi...

  11. The Giant Branches of ω Centauri: Multiwavelength Observations of Evolved Stars

    Science.gov (United States)

    Hughes, Joanne; Wallerstein, George; van Leeuwen, Floor; Hilker, Michael

    2004-02-01

    We have obtained photometric observations in a 182 arcmin2 area, 25' to the north of the center of the globular cluster ω Centauri. The Strömgren vby and broadband BI filters were used to obtain measurements for some 2500 stars. Preliminary examinations of parts of the data have been presented previously (Hughes & Wallerstein, published in 2000; Hughes, Wallerstein, & van Leeuwen, published in 2002). Here we present the complete data set, study the giant branches, and use the B-I color index as a tool for assessing the ages of the populations within ω Cen. Our results confirm previous results for the main-sequence turnoff stars: there appears to be an age spread of about 3-5 Gyr among the stars of ω Cen. We use the proper-motion study by van Leeuwen et al. (published in 2000) to confirm cluster membership above B~16.5 and calibrate our photometry to that of Hilker and Hilker & Richtler (both published in 2000) in order to use the improved methods described by these authors for deriving metallicity estimates from the Strömgren photometry. We use data on 25 ROA stars in our field and 40 stars from Hilker to look at the enrichment history of ω Cen. We support previous findings that there is another red giant branch, redder (Lee et al., published in 1999, and Pancino et al., published in 2000), and younger than the main giant branch but containing few stars. Even though this so-called RGB-a population appears to be younger than the bulk of the stellar population, it does not seem to be younger than the most metal-rich tail of the bulk population. This last property suggests that the RGB-a may not have been the last burst of star formation in ω Cen and could support the idea, presented by Ferraro et al. and Pancino et al. (both in 2002), that it represents an accreted stellar system.

  12. Chemical abundances in the multiple sub-giant branch of 47 Tucanae: insights on its faint sub-giant branch component

    Science.gov (United States)

    Marino, A. F.; Milone, A. P.; Casagrande, L.; Collet, R.; Dotter, A.; Johnson, C. I.; Lind, K.; Bedin, L. R.; Jerjen, H.; Aparicio, A.; Sbordone, L.

    2016-06-01

    The globular cluster 47 Tuc exhibits a complex sub-giant branch (SGB) with a faint-SGB comprising only about the 10 per cent of the cluster mass and a bright-SGB hosting at least two distinct populations. We present a spectroscopic analysis of 62 SGB stars including 21 faint-SGB stars. We thus provide the first chemical analysis of the intriguing faint-SGB population and compare its abundances with those of the dominant populations. We have inferred abundances of Fe, representative light elements C, N, Na, and Al, α elements Mg and Si for individual stars. Oxygen has been obtained by co-adding spectra of stars on different sequences. In addition, we have analysed 12 stars along the two main RGBs of 47 Tuc. Our principal results are (i) star-to-star variations in C/N/Na among RGB and bright-SGB stars; (ii) substantial N and Na enhancements for the minor population corresponding to the faint-SGB; (iii) no high enrichment in C+N+O for faint-SGB stars. Specifically, the C+N+O of the faint-SGB is a factor of 1.1 higher than the bright-SGB, which, considering random (±1.3) plus systematic errors (±0.3), means that their C+N+O is consistent within observational uncertainties. However, a small C+N+O enrichment for the faint-SGB, similar to what predicted on theoretical ground, cannot be excluded. The N and Na enrichment of the faint-SGB qualitatively agrees with this population possibly being He-enhanced, as suggested by theory. The iron abundance of the bright and faint-SGB is the same to a level of ˜0.10 dex, and no other significant difference for the analysed elements has been detected.

  13. Medium-resolution Spectroscopy of Red Giant Branch Stars in ω Centauri

    Science.gov (United States)

    An, Deokkeun; Lee, Young Sun; In Jung, Jae; Rey, Soo-Chang; Rhee, Jaehyon; Lee, Jae-Woo; Lee, Young-Wook; Joe, Young Hoon

    2017-10-01

    We present [Fe/H] and [Ca/Fe] of ∼600 red giant branch (RGB) members of the globular cluster Omega Centauri (ω {Cen}). We collect medium-resolution (R∼ 2000) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory equipped with Hydra, the fiber-fed multi-object spectrograph. We demonstrate that blending of stellar light in optical fibers severely limits the accuracy of spectroscopic parameters in the crowded central region of the cluster. When photometric temperatures are taken in the spectroscopic analysis, our kinematically selected cluster members, excluding those that are strongly affected by flux from neighboring stars, include relatively fewer stars at intermediate metallicity ([{Fe}/{{H}}]∼ -1.5) than seen in the previous high-resolution survey for brighter giants in Johnson & Pilachowski. As opposed to the trend of increasing [Ca/Fe] with [Fe/H] found by those authors, our [Ca/Fe] estimates, based on Ca ii H & K measurements, show essentially the same mean [Ca/Fe] for most of the metal-poor and metal-intermediate populations in this cluster, suggesting that mass- or metallicity-dependent SN II yields may not be necessary in their proposed chemical evolution scenario. Metal-rich cluster members in our sample show a large spread in [Ca/Fe], and do not exhibit a clear bimodal distribution in [Ca/Fe]. We also do not find convincing evidence for a radial metallicity gradient among RGB stars in ω {Cen}.

  14. The Destruction of 3He by Rayleigh-Taylor Instability on the First Giant Branch

    CERN Document Server

    Eggleton, P P; Lattanzio, J C

    2006-01-01

    Low-mass stars, ~1-2 solar masses, near the Main Sequence are efficient at producing 3He, which they mix into the convective envelope on the giant branch and distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the observed cosmic abundance of 3He with the predictions of Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell. In this zone the burning of the 3He left behind by the retreating convective envelope is predominantly by the reaction 3He + 3He -> 4He + 2p, a reaction which, untypically for stellar nuclear reactions, {\\it lowers} the mean molecular weight, leading to a local minimum. This local minimum ...

  15. Carbon and Nitrogen Abundance Variations Among Red Giant Branch Stars in M10

    Science.gov (United States)

    Gerber, Jeffrey M.; Friel, Eileen D.; Vesperini, Enrico

    2016-06-01

    We present analysis of the CN and CH molecular band strengths derived for red giants in M10 as part of a first pilot study in the WIYN Indiana Northern Globular Survey (WINGS). This survey plans to use a combination of low-resolution spectroscopy taken with Hydra and wide-field SDSS filter photometry taken with the newly upgraded ODI to study the multiple populations and dynamics of a sample of Milky Way globular clusters. Our sample comes from the first in a series of observation runs conducted in Aug. 2014 using Hydra on the WIYN 3.5m telescope. CN and CH bands are measured for ~100 red giant branch stars and used to characterize the distribution in band strength and to derive carbon and nitrogen abundances by comparing observed band strengths to synthetic spectra produced by the Synthetic Spectrum Generator (SSG), which makes use of MARCS model atmospheres. Band strengths and CN abundances are used to investigate the distribution of stars in nitrogen normal and enhanced populations and to compare these to other ways of characterizing multiple stellar populations with other light elements (such as Na and O).

  16. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars III. Dust production at supersolar metallicities

    CERN Document Server

    Nanni, Ambra; Marigo, Paola; Girardi, Léo

    2013-01-01

    We extend the formalism presented in our recent calculations of dust ejecta from the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase, to the case of super-solar metallicity stars. The TP-AGB evolutionary models are computed with the COLIBRI code. We adopt our preferred scheme for dust growth. For M-giants, we neglect chemisputtering by H$_2$ molecules and, for C-stars we assume a homogeneous growth scheme which is primarily controlled by the carbon over oxygen excess. At super-solar metallicities, dust forms more efficiently and silicates tend to condense significantly closer to the photosphere (r~1.5 R$_*$) - and thus at higher temperatures and densities - than at solar and sub-solar metallicities (r~2-3 R$_*$). In such conditions, the hypothesis of thermal decoupling between gas and dust becomes questionable, while dust heating due to collisions plays an important role. The heating mechanism delays dust condensation to slightly outer regions in the circumstellar envelope. We find that the same mech...

  17. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars II. Dust production at varying metallicity

    CERN Document Server

    Nanni, Ambra; Marigo, Paola; Girardi, Léo

    2013-01-01

    We present the dust ejecta of the new stellar models for the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase computed with the COLIBRI code. We use a formalism of dust growth coupled with a stationary wind for both M and C-stars. In the original version of this formalism, the most efficient destruction process of silicate dust in M-giants is chemisputtering by H2 molecules. For these stars we find that dust grains can only form at relatively large radial distances (r~5 R*), where they cannot be efficiently accelerated, in agreement with other investigations. In the light of recent laboratory results, we also consider the alternative case that the condensation temperature of silicates is determined only by the competition between growth and free evaporation processes (i.e. no chemisputtering). With this latter approach we obtain dust condensation temperatures that are significantly higher (up to Tcond~1400 K) than those found when chemisputtering is included (Tcond~900 K), and in better agreement with...

  18. High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T. J. L.; Hill, V.; Tolstoy, E.; Irwin, M. J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Martins, F.; Bournaud, F.; Monier, R.; Reylé, C.

    2014-01-01

    From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf spheroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between --2.0 and

  19. High resolution spectroscopy of Red Giant Branch stars and the chemical evolution of the Fornax dwarf spheroidal galaxy

    NARCIS (Netherlands)

    Lemasle, B.; de Boer, T.J.L.; Hill, V.; Tolstoy, E.; Irwin, M.J.; Jablonka, P.; Venn, K.; Battaglia, G.; Starkenburg, E.; Shetrone, M.; Letarte, B.; Francois, P.; Helmi, A.; Primas, F.; Kaufer, A.; Szeifert, T.; Ballet, J.; Bournaud, F.; Martins, F.; Monier, R.; Reyle, C.

    2014-01-01

    From VLT-FLAMES high-resolution spectra, we determine the abundances of several α, iron-peak and neutron-capture elements in 47 Red Giant Branch stars in the Fornax dwarf speroidal galaxy. We confirm that SNe Ia started to contribute to the chemical enrichment of Fornax at [Fe/H] between -2.0 and -

  20. NGC 362: another globular cluster with a split red giant branch

    CERN Document Server

    Carretta, E; Gratton, R G; Lucatello, S; D'Orazi, V; Bellazzini, M; Catanzaro, G; Leone, F; Momany, Y; Sollima, A

    2013-01-01

    We obtained FLAMES GIRAFFE+UVES spectra for both first and second-generation red giant branch (RGB) stars in the globular cluster (GC) NGC 362 and used them to derive abundances of 21 atomic species for a sample of 92 stars. The surveyed elements include proton-capture (O, Na, Mg, Al, Si), alpha-capture (Ca, Ti), Fe-peak (Sc, V, Mn, Co, Ni, Cu), and neutron-capture elements (Y, Zr, Ba, La, Ce, Nd, Eu, Dy). The analysis is fully consistent with that presented for twenty GCs in previous papers of this series. Stars in NGC 362 seem to be clustered into two discrete groups along the Na-O anti-correlation, with a gap at [O/Na] 0 dex. Na-rich, second generation stars show a trend to be more centrally concentrated, although the level of confidence is not very high. When compared to the classical second-parameter twin NGC 288, with similar metallicity, but different horizontal branch type and much lower total mass, the proton-capture processing in stars of NGC 362 seems to be more extreme, confirming previous analysi...

  1. The spectroscopic indistinguishability of red giant branch and red clump stars

    Science.gov (United States)

    Masseron, T.; Hawkins, K.

    2017-01-01

    Context. Stellar spectroscopy provides useful information on the physical properties of stars such as effective temperature, metallicity and surface gravity. However, those photospheric characteristics are often hampered by systematic uncertainties. The joint spectro-sismo project (APOGEE+Kepler, aka APOKASC) of field red giants has revealed a puzzling offset between the surface gravities (log g) determined spectroscopically and those determined using asteroseismology, which is largely dependent on the stellar evolutionary status. Aims: Therefore, in this letter, we aim to shed light on the spectroscopic source of the offset. Methods: We used the APOKASC sample to analyse the dependencies of the log g discrepancy as a function of stellar mass and stellar evolutionary status. We discuss and study the impact of some neglected abundances on spectral analysis of red giants, such as He and carbon isotopic ratio. Results: We first show that, for stars at the bottom of the red giant branch where the first dredge-up had occurred, the discrepancy between spectroscopic log g and asteroseismic log g depends on stellar mass. This seems to indicate that the log g discrepancy is related to CN cycling. Among the CN-cycled elements, we demonstrate that the carbon isotopic ratio (12C /13C) has the largest impact on stellar spectrum. In parallel, we observe that this log g discrepancy shows a similar trend as the 12C /13C ratios as expected by stellar evolution theory. Although we did not detect a direct spectroscopic signature of 13C, other corroborating evidences suggest that the discrepancy in log g is tightly correlated to the production of 13C in red giants. Moreover, by running the data-driven algorithm (the Cannon) on a synthetic grid trained on the APOGEE data, we try to evaluate more quantitatively the impact of various 12C /13C ratios. Conclusions: While we have demonstrated that 13C indeed impacts all parameters, the size of the impact is smaller than the observed offset

  2. Evolution of thermally pulsing asymptotic giant branch stars - III. Dust production at supersolar metallicities

    Science.gov (United States)

    Nanni, Ambra; Bressan, Alessandro; Marigo, Paola; Girardi, Léo

    2014-03-01

    We extend the formalism presented in our recent calculations of dust ejecta from the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase to the case of super-solar metallicity stars. The TP-AGB evolutionary models are computed with the COLIBRI code. We adopt our preferred scheme for dust growth. For M-giants, we neglect chemisputtering by H2 molecules and for C-stars we assume a homogeneous growth scheme which is primarily controlled by the carbon over oxygen excess. At super-solar metallicities, dust forms more efficiently and silicates tend to condense significantly closer to the photosphere (r ˜ 1.5R*) - and thus at higher temperatures and densities - than at solar and sub-solar metallicities (r ˜ 2-3R*). In such conditions, the hypothesis of thermal decoupling between gas and dust becomes questionable, while dust heating due to collisions plays an important role. The heating mechanism delays dust condensation to slightly outer regions in the circumstellar envelope. We find that the same mechanism is not significant at solar and sub-solar metallicities. The main dust products at super-solar metallicities are silicates. We calculate the total dust ejecta and dust-to-gas ejecta, for various values of the stellar initial masses and initial metallicities Z = 0.04, 0.06. Merging these new calculations with those for lower metallicities it turns out that, contrary to what is often assumed, the total dust-to-gas ejecta of intermediate-mass stars exhibit only a weak dependence on the initial metal content.

  3. Evolution of thermally pulsing asymptotic giant branch stars - II. Dust production at varying metallicity

    Science.gov (United States)

    Nanni, Ambra; Bressan, Alessandro; Marigo, Paola; Girardi, Léo

    2013-09-01

    We present the dust ejecta of the new stellar models for the thermally pulsing asymptotic giant branch (TP-AGB) phase computed with the COLIBRI code. We use a formalism of dust growth coupled with a stationary wind for both M- and C-stars. In the original version of this formalism, the most efficient destruction process of silicate dust in M-giants is chemisputtering by H2 molecules. For these stars, we find that dust grains can only form at relatively large radial distances (r ˜ 5R*), where they cannot be efficiently accelerated, in agreement with other investigations. In the light of recent laboratory results, we also consider the alternative case that the condensation temperature of silicates is determined only by the competition between growth and free evaporation processes (i.e. no chemisputtering). With this latter approach we obtain dust condensation temperatures that are significantly higher (up to Tcond ˜ 1400 K) than those found when chemisputtering is included (Tcond ˜ 900 K), and in better agreement with condensation experiments. As a consequence, silicate grains can remain stable in inner regions of the circumstellar envelopes (r ˜ 2 R*), where they can rapidly grow and can be efficiently accelerated. With this modification, our models nicely reproduce the observed trend between terminal velocities and mass-loss rates of Galactic M-giants. For C-stars the formalism is based on the homogeneous growth scheme where the key role is played by the carbon over oxygen excess. The models reproduce fairly well the terminal velocities of Galactic stars and there is no need to invoke changes in the standard assumptions. At decreasing metallicity the carbon excess becomes more pronounced and the efficiency of dust formation increases. This trend could be in tension with recent observational evidence in favour of a decreasing efficiency, at decreasing metallicity. If confirmed by more observational data, it would indicate that either the amount of the carbon

  4. VLT/FLAMES spectroscopy of Red Giant Branch stars in the Carina dwarf spheroidal galaxy

    CERN Document Server

    Lemasle, B; Tolstoy, E; Venn, K A; Shetrone, M D; Irwin, M J; de Boer, T J L; Starkenburg, E; Salvadori, S

    2011-01-01

    The ages of individual Red Giant Branch stars (RGB) can range from 1 Gyr old to the age of the Universe, and it is believed that the abundances of most chemical elements in their photospheres remain unchanged with time (those that are not affected by the 1st dredge-up). This means that they trace the ISM in the galaxy at the time the star formed, and hence the chemical enrichment history of the galaxy. CMD analysis has shown the Carina dwarf spheroidal (dSph) to have had an unusually episodic star formation history (SFH) which is expected to be reflected in the abundances of different chemical elements. We use the VLT-FLAMES spectrograph in HR mode (R~20000) to measure the abundances of several chemical elements in a sample of 35 RGB stars in Carina. We also combine these abundances with photometry to derive age estimates for these stars. This allows us to determine which of two distinct star formation (SF) episodes the stars in our sample belong to, and thus to define the relationship between SF and chemical...

  5. VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy

    CERN Document Server

    Lemasle, B; Hill, V; Tolstoy, E; Irwin, M; Jablonka, P; Venn, K; Battaglia, G; Starkenburg, E; Shetrone, M; Letarte, B; Francois, P; Helmi, A; Primas, F; Kaufer, A; Szeifert, T

    2014-01-01

    Fornax is one of the most massive dwarf spheroidal galaxies in the Local Group. The Fornax field star population is dominated by intermediate age stars but star formation was going on over almost its entire history. It has been proposed that Fornax experienced a minor merger event. Despite recent progress, only the high metallicity end of Fornax field stars ([Fe/H]>-1.2 dex) has been sampled in larger number via high resolution spectroscopy. We want to better understand the full chemical evolution of this galaxy by better sampling the whole metallicity range, including more metal poor stars. We use the VLT-FLAMES multi-fibre spectrograph in high-resolution mode to determine the abundances of several alpha, iron-peak and neutron-capture elements in a sample of 47 individual Red Giant Branch stars in the Fornax dwarf spheroidal galaxy. We combine these abundances with accurate age estimates derived from the age probability distribution from the colour-magnitude diagram of Fornax. Similar to other dwarf spheroid...

  6. The Core Mass Growth and Stellar Lifetime of Thermally Pulsing Asymptotic Giant Branch Stars

    CERN Document Server

    Kalirai, Jason S; Tremblay, Pier-Emmanuel

    2013-01-01

    We establish new constraints on the intermediate-mass range of the initial-final mass relation by studying white dwarfs in four young star clusters, and apply the results to study the evolution of stars on the thermally pulsing asymptotic giant branch (TP-AGB). We show that the stellar core mass on the AGB grows rapidly from 10% to 30% for stars with $M_{\\rm initial}$ = 1.6 to 2.0 $M_\\odot$. At larger masses, the core-mass growth decreases steadily to $\\sim$10% at $M_{\\rm initial}$ = 3.4 $M_\\odot$. These observations are in excellent agreement with predictions from the latest TP-AGB evolutionary models in Marigo et al. (2013). We also compare to models with varying efficiencies of the third dredge-up and mass loss, and demonstrate that the process governing the growth of the core is largely the stellar wind, while the third dredge-up plays a secondary, but non-negligible role. Based on the new white dwarf measurements, we perform an exploratory calibration of the most popular mass-loss prescriptions in the li...

  7. Luminosities of Carbon-rich Asymptotic Giant Branch stars in the Milky Way

    CERN Document Server

    Guandalini, Roald

    2013-01-01

    Stars evolving along the Asymptotic Giant Branch can become Carbon-rich in the final part of their evolution. They replenish the inter-stellar medium with nuclear processed material via strong radiative stellar winds. The determination of the luminosity function of these stars, even if far from being conclusive, is extremely important to test the reliability of theoretical models. In particular, strong constraints on the mixing treatment and the mass-loss rate can be derived. We present an updated Luminosity Function of Galactic Carbon Stars obtained from a re-analysis of available data already published in previous papers. Starting from available near- and mid-infrared photometric data, we re-determine the selection criteria. Moreover, we take advantage from updated distance estimates and Period-Luminosity relations and we adopt a new formulation for the computation of Bolometric Corrections. This leads us to collect an improved sample of carbon-rich sources from which we construct an updated Luminosity Func...

  8. Heavy Element Nucleosynthesis in the Brightest Galactic Asymptotic Giant Branch stars

    CERN Document Server

    Karakas, Amanda I; Lugaro, Maria

    2012-01-01

    We present updated calculations of stellar evolutionary sequences and detailed nucleosynthesis predictions for the brightest asymptotic giant branch (AGB) stars in the Galaxy with masses between 5Msun to 9Msun, with an initial metallicity of Z =0.02 ([Fe/H] = 0.14). In our previous studies we used the Vassiliadis & Wood (1993) mass-loss rate, which stays low until the pulsation period reaches 500 days after which point a superwind begins. Vassiliadis & Wood noted that for stars over 2.5Msun the superwind should be delayed until P ~ 750 days at 5Msun. We calculate evolutionary sequences where we delay the onset of the superwind to pulsation periods of P ~ 700-800 days in models of M = 5, 6, and 7Msun. Post-processing nucleosynthesis calculations show that the 6 and 7Msun models produce the most Rb, with [Rb/Fe] ~ 1 dex, close to the average of most of the Galactic Rb-rich stars ([Rb/Fe] ~ 1.4 plus or minus 0.8 dex). Changing the rate of the 22Ne + alpha reactions results in variations of [Rb/Fe] as lar...

  9. Infrared tip of the red giant branch and distances to the MAFFEI/IC 342 group

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Po-Feng; Tully, R. Brent; Jacobs, Bradley A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, HI 96822 (United States); Rizzi, Luca [W. M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Dolphin, Andrew E. [Raytheon, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Karachentsev, Igor D. [Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz, Karachai-Cherkessian Republic 369167 (Russian Federation)

    2014-07-01

    In this paper, we extend the use of the tip of the red giant branch (TRGB) method to near-infrared wavelengths from the previously used I-band, using the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). Upon calibration of a color dependency of the TRGB magnitude, the IR TRGB yields a random uncertainty of ∼5% in relative distance. The IR TRGB methodology has an advantage over the previously used Advance Camera for Surveys F606W and F814W filter set for galaxies that suffer from severe extinction. Using the IR TRGB methodology, we obtain distances toward three principal galaxies in the Maffei/IC 342 complex, which are located at low Galactic latitudes. New distance estimates using the TRGB method are 3.45{sub −0.13}{sup +0.13} Mpc for IC 342, 3.37{sub −0.23}{sup +0.32} Mpc for Maffei 1, and 3.52{sub −0.30}{sup +0.32} Mpc for Maffei 2. The uncertainties are dominated by uncertain extinction, especially for Maffei 1 and Maffei 2. Our IR calibration demonstrates the viability of the TRGB methodology for observations with the James Webb Space Telescope.

  10. Infrared Tip of the Red Giant Branch and Distances to the Maffei/IC 342 Group

    CERN Document Server

    Wu, Po-Feng; Rizzi, Luca; Dolphin, Andrew E; Jacobs, Bradley A; Karachentsev, Igor D

    2014-01-01

    In this paper, we extend the use of the tip of the red giant branch (TRGB) method to near-infrared wavelengths from previously-used $I$-band, using the \\textit{Hubble Space Telescope (HST)} Wide Field Camera 3 (WFC3). Upon calibration of a color dependency of the TRGB magnitude, the IR TRGB yields a random uncertainty of $\\sim 5%$ in relative distance. The IR TRGB methodology has an advantage over the previously-used ACS $F606W$ and $F814W$ filter set for galaxies that suffer from severe extinction. Using the IR TRGB methodology, we obtain distances toward three principal galaxies in the Maffei/IC 342 complex, which are located at low Galactic latitudes. New distance estimates using the TRGB method are 3.45$^{+0.13}_{-0.13}$ Mpc for IC 342, 3.37$^{+0.32}_{-0.23}$ Mpc for Maffei 1 and 3.52$^{+0.32}_{-0.30}$ Mpc for Maffei 2. The uncertainties are dominated by uncertain extinction, especially for Maffei 1 and Maffei 2. Our IR calibration demonstrates the viability of the TRGB methodology for observations with t...

  11. A Spitzer Space Telescope Survey of Extreme Asymptotic Giant Branch Stars in M32

    Science.gov (United States)

    Jones, O.C.; McDonald, I.; Rich, R.M.; Kemper, F.; Boyer, M.L.; Zijlstra, A.A.; Bendo, G.J.

    2014-01-01

    We investigate the population of cool, evolved stars in the Local Group dwarf elliptical galaxy M32, using Infrared Array Camera observations from the Spitzer Space Telescope. We construct deep mid-infrared colour-magnitude diagrams for the resolved stellar populations within 3.5 arcminutes of M32's centre, and identify those stars that exhibit infrared excess. Our data is dominated by a population of luminous, dustproducing stars on the asymptotic giant branch (AGB) and extend to approximately 3 magnitudes below the AGB tip. We detect for the first time a sizeable population of 'extreme' AGB stars, highly enshrouded by circumstellar dust and likely completely obscured at optical wavelengths. The total dust-injection rate from the extreme AGB candidates is measured to be 7.5 x 10 (sup -7) solar masses per year, corresponding to a gas mass-loss rate of 1.5 x 10 (sup -4) solar masses per year. These extreme stars may be indicative of an extended star-formation epoch between 0.2 and 5 billion years ago.

  12. Evolution and nucleosynthesis of helium-rich asymptotic giant branch models

    CERN Document Server

    Shingles, Luke J; Karakas, Amanda I; Stancliffe, Richard J; Lattanzio, John C; Lugaro, Maria

    2015-01-01

    There is now strong evidence that some stars have been born with He mass fractions as high as $Y \\approx 0.40$ (e.g., in $\\omega$ Centauri). However, the advanced evolution, chemical yields, and final fates of He-rich stars are largely unexplored. We investigate the consequences of He-enhancement on the evolution and nucleosynthesis of intermediate-mass asymptotic giant branch (AGB) models of 3, 4, 5, and 6 M$_\\odot$ with a metallicity of $Z = 0.0006$ ([Fe/H] $\\approx -1.4$). We compare models with He-enhanced compositions ($Y=0.30, 0.35, 0.40$) to those with primordial He ($Y=0.24$). We find that the minimum initial mass for C burning and super-AGB stars with CO(Ne) or ONe cores decreases from above our highest mass of 6 M$_\\odot$ to $\\sim$ 4-5 M$_\\odot$ with $Y=0.40$. We also model the production of trans-Fe elements via the slow neutron-capture process (s-process). He-enhancement substantially reduces the third dredge-up efficiency and the stellar yields of s-process elements (e.g., 90% less Ba for 6 M$_\\o...

  13. A test for asymptotic giant branch evolution theories: Planetary Nebulae in the Large Magellanic Cloud

    CERN Document Server

    Ventura, P; Dell'Agli, F; García-Hernández, D A; Di Criscienzo, M

    2015-01-01

    We used a new generation of asymptotic giant branch (AGB) stellar models that include dust formation in the stellar winds to find the links between evolutionary models and the observed properties of a homogeneous sample of Large Magellanic Cloud (LMC) planetary nebulae (PNe). Comparison between the evolutionary yields of elements such as CNO and the corresponding observed chemical abundances is a powerful tool to shed light on evolutionary processes such as hot bottom burning (HBB) and third dredge-up (TDU). We found that the occurrence of HBB is needed to interpret the nitrogen-enriched (log(N/H)+12>8) PNe. In particular, N-rich PNe with the lowest carbon content are nicely reproduced by AGB models of mass M >=6 Mo, whose surface chemistry reflects the pure effects of HBB. PNe with log(N/H)+12<7.5 correspond to ejecta of stars that have not experienced HBB, with initial mass below about 3 Mo. Some of these stars show very large carbon abundances, owing to the many TDU episodes experienced. We found from o...

  14. The double sub-giant branch of NGC 6656 (M22): a chemical characterization

    CERN Document Server

    Marino, A F; Sneden, C; Bergemann, M; Kraft, R P; Wallerstein, G; Cassisi, S; Aparicio, A; Asplund, M; Bedin, R L; Hilker, M; Lind, K; Momany, Y; Piotto, G; Roederer, I U; Stetson, P B; Zoccali, M

    2012-01-01

    We present an abundance analysis of 101 subgiant branch (SGB) stars in the globular cluster M22. Using low resolution FLAMES/GIRAFFE spectra we have determined abundances of the neutron-capture strontium and barium and the light element carbon. With these data we explore relationships between the observed SGB photometric split in this cluster and two stellar groups characterized by different contents of iron, slow neutron-capture process (s-process) elements, and the alpha element calcium, that we previously discovered in M22’s red-giant stars. We show that the SGB stars correlate in chemical composition and color-magnitude diagram position: the stars with higher metallicity and relative s-process abundances define a fainter SGB, while stars with lower metallicity and s-process content reside on a relatively brighter SGB. This result has implications for the relative ages of the two stellar groups of M22. In particular, it is inconsistent with a large spread in ages of the two SGBs. By accounting for the...

  15. A Spitzer Space Telescope survey of extreme Asymptotic Giant Branch stars in M32

    CERN Document Server

    Jones, O C; Rich, R M; Kemper, F; Boyer, M L; Zijlstra, A A; Bendo, G J

    2014-01-01

    We investigate the population of cool, evolved stars in the Local Group dwarf elliptical galaxy M32, using Infrared Array Camera observations from the Spitzer Space Telescope. We construct deep mid-infrared colour-magnitude diagrams for the resolved stellar populations within 3.5 arcmin of M32's centre, and identify those stars that exhibit infrared excess. Our data is dominated by a population of luminous, dust-producing stars on the asymptotic giant branch (AGB) and extend to approximately 3 mag below the AGB tip. We detect for the first time a sizeable population of `extreme' AGB stars, highly enshrouded by circumstellar dust and likely completely obscured at optical wavelengths. The total dust-injection rate from the extreme AGB candidates is measured to be $7.5 \\times 10^{-7}$ ${\\rm M}_{\\odot} \\, {\\rm yr}^{-1}$, corresponding to a gas mass-loss rate of $1.5 \\times 10^{-4}$ ${\\rm M}_{\\odot} \\, {\\rm yr}^{-1}$. These extreme stars may be indicative of an extended star-formation epoch between 0.2 and 5 Gyr a...

  16. The orbital evolution of asteroids, pebbles and planets from giant branch stellar radiation and winds

    CERN Document Server

    Veras, Dimitri; Gaensicke, Boris T

    2015-01-01

    The discovery of over 50 planets around evolved stars and more than 35 debris discs orbiting white dwarfs highlight the increasing need to understand small body evolution around both early and asymptotic giant branch (GB) stars. Pebbles and asteroids are susceptible to strong accelerations from the intense luminosity and winds of GB stars. Here, we establish equations that can model time-varying GB stellar radiation, wind drag and mass loss. We derive the complete three-dimensional equations of motion in orbital elements due to (1) the Epstein and Stokes regimes of stellar wind drag, (2) Poynting-Robertson drag, and (3) the Yarkovsky drift with seasonal and diurnal components. We prove through averaging that the potential secular eccentricity and inclination excitation due to Yarkovsky drift can exceed that from Poynting-Robertson drag and radiation pressure by at least three orders of magnitude, possibly flinging asteroids which survive YORP spin-up into a widely dispersed cloud around the resulting white dw...

  17. Measuring The Mass Loss Evolution at The Tip of The Asymptotic Giant Branch

    CERN Document Server

    Sandin, C; Schönberner, D

    2009-01-01

    In the final stages of stellar evolution low- to intermediate-mass stars lose their envelope in increasingly massive stellar winds. Such winds affect the interstellar medium as well as the circumstellar envelope where planetary nebulae form subsequently. Characteristics of this mass loss depends on both stellar properties and properties of gas and dust in the wind formation region. In a recent study we measure the mass loss evolution, and other properties, using four planetary nebulae in the galactic disk. Specifically we use the method of integral field spectroscopy on faint halos, which are found outside the much brighter central parts of the planetary nebula. Here we present the outcome of our approach. We also make a brief comparison with other existing methods, which, so far, are used to measure previous stages of mass loss on the asymptotic giant branch. We then discuss the occurrence and observables of halos of planetary nebulae. We finish with a discussion on how our observations of the mass loss evol...

  18. Dust-enshrouded Asymptotic Giant Branch Stars in the Solar Neighbourhood

    CERN Document Server

    Olivier, E A; Marang, F; Olivier, Enrico A.; Whitelock, Patricia; Marang, Fred

    2001-01-01

    A study is made of a sample of 58 dust-enshrouded Asymptotic Giant Branch (AGB) stars (including 2 possible post AGB stars), of which 27 are carbon-rich and 31 are oxygen-rich. These objects were originally identified by Jura & Kleinmann as nearby (within about 1 kpc of the sun) AGB stars with high mass-loss rates, greater than 1E-6 solar masses per year. Ground-based near-infrared photometry, data obtained by IRAS and kinematic data from the literature are combined to investigate the properties of these stars. The light amplitude in the near-infrared is found to be correlated with period, and this amplitude decreases with increasing wavelength. Statistical tests show that there is no reason to suspect any difference in the period distributions of the carbon- and oxygen-rich stars for periods less than 1000 days, and no carbon-rich star has a period longer than 1000 days. The colours are consistent with those of cool stars with evolved circumstellar dust-shells. Luminosities and distances are estimated us...

  19. New light on Galactic post-asymptotic giant branch stars. I. First distance catalogue

    CERN Document Server

    Vickers, Shane B; Parker, Ouentin A; Bojicic, Ivan S

    2014-01-01

    We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Toru\\'n catalogue of Szczerba et al., and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are essential in determining meaningful physical characteristics for these sources and this has been difficult to determine for most objects previously. The distances were determined by modelling their spectral energy distributions (SED) with multiple black-body curves, and integrating under the overall fit to determine the total distance-dependent flux. This method works because the luminosity of these central stars is very nearly constant from the tip of the AGB phase to the beginning of the white-dwarf cooling track. This then enables us to use a standard-candle luminosity to estimate the SED distances. For Galactic thin disk PAGB objects, we use three luminosity bins...

  20. Asymptotic Giant Branch stars at low metallicity: the challenging interplay between mass loss and molecular opacities

    CERN Document Server

    Ventura, Paolo

    2010-01-01

    We investigate the main physical properties of low-metallicity Asymptotic Giant Branch stars, with the aim of quantifying the uncertainties that presently affect the predicted chemical yields of these stars, associated to mass loss and description of molecular opacities. We find that above a threshold mass, M ~ 3.5Msun for Z=0.001, the results are little dependent on the opacity treatment, as long as hot-bottom burning prevents the surface C/O ratio from exceeding unity; the yields of these massive AGB stars are expected to be mostly determined by the efficiency of convection, with a relatively mild dependence on the mass-loss description. A much higher degree of uncertainty is associated to the yields of less massive models, which critically depend on the adopted molecular opacities. An interval of masses exists, say 2.0-3.0Msun, (the exact range depends on mass loss), in which HBB may be even extinguished following the cooling produced by the opacity of C-bearing molecules. The yields of these stars are the...

  1. The brightness of the red giant branch tip. Theoretical framework, a set of reference models, and predicted observables

    Science.gov (United States)

    Serenelli, A.; Weiss, A.; Cassisi, S.; Salaris, M.; Pietrinferni, A.

    2017-10-01

    Context. The brightness of the tip of the red giant branch is a useful reference quantity for several fields of astrophysics. An accurate theoretical prediction is needed for such purposes. Aims: We provide a solid theoretical prediction for the brightness of the tip of the red giant branch, valid for a reference set of standard physical assumptions, and mostly independent of numerical details. Methods: We examine the dependence on physical assumptions and numerical details for a wide range of metallicities and masses and based on two different stellar evolution codes. We adjust differences between the codes to treat the physics as identically as possible. After we have succeeded in reproducing the tip brightness between the codes, we present a reference set of models based on the most up to date physical inputs, but neglecting microscopic diffusion, and convert theoretical luminosities to observed infrared colours suitable for observations of resolved populations of stars and include analytic fits to facilitate their use. Results: We find that consistent use of updated nuclear reactions, including an appropriate treatment of the electron screening effects, and careful time-stepping on the upper red giant branch are the most important aspects to bring initially discrepant theoretical values into agreement. Small but visible differences remain unexplained for very low metallicities and mass values at and above 1.2 M⊙, corresponding to ages younger than 4 Gyr. The colour transformations introduce larger uncertainties than the differences between the two stellar evolution codes. Conclusions: We demonstrate that careful stellar modelling allows an accurate prediction for the luminosity of the red giant branch tip. Differences to empirically determined brightnesses may result either from insufficient colour transformations or from deficits in the constitutional physics. We present the best-tested theoretical reference values to date.

  2. Lost and found: evidence of Second Generation stars along the Asymptotic Giant Branch of the globular cluster NGC 6752

    CERN Document Server

    Lapenna, E; Mucciarelli, A; Salaris, M; Ferraro, F R; Lanzoni, B; Massari, D; Stetson, P B; Cassisi, S; Savino, A

    2016-01-01

    We derived chemical abundances for C, N, O, Na, Mg and Al in 20 asymptotic giant branch (AGB) stars in the globular cluster NGC 6752. All these elements (but Mg) show intrinsic star-to-star variations and statistically significant correlations or anticorrelations analogous to those commonly observed in red giant stars of globular clusters hosting multiple populations. This demonstrates that, at odds with previous findings, both first and second generation stars populate the AGB of NGC 6752. The comparison with the Na abundances of red giant branch stars in the same cluster reveals that second generation stars (with mild Na and He enrichment) do reach the AGB phase. The only objects that are not observed along the AGB of NGC 6752 are stars with extreme Na enhancement. This is also consistent with standard stellar evolution models, showing that highly Na and He enriched stars populate the bluest portion of the horizontal branch and, because of their low stellar masses, evolve directly to the white dwarf cooling...

  3. Lost and Found: Evidence of Second-generation Stars Along the Asymptotic Giant Branch of the Globular Cluster NGC 6752

    Science.gov (United States)

    Lapenna, E.; Lardo, C.; Mucciarelli, A.; Salaris, M.; Ferraro, F. R.; Lanzoni, B.; Massari, D.; Stetson, P. B.; Cassisi, S.; Savino, A.

    2016-07-01

    We derived chemical abundances for C, N, O, Na, Mg, and Al in 20 asymptotic giant branch (AGB) stars in the globular cluster (GC) NGC 6752. All these elements (but Mg) show intrinsic star-to-star variations and statistically significant correlations or anticorrelations analogous to those commonly observed in red giant stars of GCs hosting multiple populations. This demonstrates that, at odds with previous findings, both first- and second-generation (SG) stars populate the AGB of NGC 6752. The comparison with the Na abundances of red giant branch stars in the same cluster reveals that SG stars (with mild Na and He enrichment) do reach the AGB phase. The only objects that are not observed along the AGB of NGC 6752 are stars with extreme Na enhancement. This is also consistent with standard stellar evolution models, showing that highly Na and He enriched stars populate the bluest portion of the horizontal branch and, because of their low stellar masses, evolve directly to the white dwarf cooling sequence, skipping the AGB phase. Based on observations collected at the ESO-VLT under the program 095.D-0320(A).

  4. On the oxygen abundances of M 67 stars from the turn-off point through the red-giant branch

    CERN Document Server

    Takeda, Yoichi

    2014-01-01

    With an aim to examine whether the surface oxygen composition suffers any appreciable change due to evolution-induced mixing of nuclear-processed material in the envelope of red giants, abundance determinations for O/Fe/Ni based on the synthetic spectrum-fitting method were performed by using the moderate-dispersion spectra in the 7770-7792A region (comprising O I 7771-5, Fe I 7780, and Ni I 7788 lines) for 16 stars of the old open cluster M 67 in various evolutionary stages from the turn-off point through the red giant branch. We could not find any meaningful difference in the oxygen abundances between the non-giant group (T_eff > 5000 K) and the red-giant group (T_eff < 5000 K), which are almost consistent with each other on the average (despite that both have rather large dispersions of a few tenths dex caused by insufficient data quality), though only one giant star (S 1054) appears to show an exceptionally low O abundance and thus needs a more detailed study. This result may suggest that oxygen conten...

  5. Asteroseismology of old open clusters with Kepler: direct estimate of the integrated red giant branch mass-loss in NGC 6791 and 6819

    DEFF Research Database (Denmark)

    Miglio, A.; Brogaard, Karsten Frank; Stello, D.

    2012-01-01

    Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations in G–K giants in open clusters with Kepler, we can now directly determine stellar masses for a statistic...

  6. Asteroseismology of old open clusters with Kepler: direct estimate of the integrated red giant branch mass-loss in NGC 6791 and 6819

    DEFF Research Database (Denmark)

    Miglio, A.; Brogaard, Karsten Frank; Stello, D.

    2012-01-01

    Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations in G–K giants in open clusters with Kepler, we can now directly determine stellar masses for a statistic...

  7. Asteroseismology of old open clusters with Kepler: direct estimate of the integrated red giant branch mass-loss in NGC 6791 and 6819

    NARCIS (Netherlands)

    Miglio, A.; Brogaard, K.; Stello, D.; Chaplin, W.J.; D'Antona, F.; Montalbán, J.; Basu, S.; Bressan, A.; Grundahl, F.; Pinsonneault, M.; Serenelli, A.M.; Elsworth, Y.; Hekker, S.; Kallinger, T.; Mosser, B.; Ventura, P.; Bonanno, A.; Noels, A.; Silva Aguirre, V.; Szabo, R.; Li, J.; McCauliff, S.; Middour, C.K.; Kjeldsen, H.

    2012-01-01

    Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations in G-K giants in open clusters with Kepler, we can now directly determine stellar masses for a statisticall

  8. The Pattern of CN, O, and Na Inhomogeneities on the Red Giant Branch of Messier 5

    CERN Document Server

    Smith, Graeme H; Hamren, Katherine M

    2013-01-01

    Data from the literature are used to explore the relation between $\\lambda$3883 CN band strength and the sodium and oxygen abundances of red giants in the globular cluster Messier 5. Although there is a broad tendency for CN-strong giants in this cluster to have higher sodium abundances and lower oxygen abundances than CN-weak giants of comparable absolute magnitude there are some secondary features in these relations. The oxygen abundance [O/Fe] shows a greater range (0.6-0.7 dex) among the CN-strong giants than the CN-weak giants (approximately 0.3 dex). By contrast [Na/Fe] shows a 0.6-0.7 dex range among the CN-weak giants, but a more limited range of 0.3-0.4 dex among the CN-strong giants. The $\\lambda$3883 CN band anticorrelates in strength with [O/Fe] among the CN-strong giants, but there is little, if any, such trend among the CN-weak giants. In contrast, the CN band strength may show a modest correlation with [Na/Fe] among the CN-weak giants, but there is little evidence for such among the CN-strong g...

  9. Clear evidence for the presence of second-generation asymptotic giant branch stars in metal-poor Galactic globular clusters

    CERN Document Server

    Garcia-Hernandez, D A; Monelli, M; Cassisi, S; Stetson, P B; Zamora, O; Shetrone, M; Lucatello, S

    2015-01-01

    Galactic globular clusters (GCs) are known to host multiple stellar populations: a first generation with a chemical pattern typical of halo field stars and a second generation (SG) enriched in Na and Al and depleted in O and Mg. Both stellar generations are found at different evolutionary stages (e.g., the main-sequence turnoff, the subgiant branch, and the red giant branch). The non detection of SG asymptotic giant branch (AGB) stars in several metal-poor ([Fe/H] < -1) GCs suggests that not all SG stars ascend the AGB phase, and that failed AGB stars may be very common in metal-poor GCs. This observation represents a serious problem for stellar evolution and GC formation/evolution theories. We report fourteen SG-AGB stars in four metal-poor GCs (M 13, M 5, M 3, and M 2) with different observational properties: horizontal branch (HB) morphology, metallicity, and age. By combining the H-band Al abundances obtained by the APOGEE survey with ground-based optical photometry, we identify SG Al-rich AGB stars in...

  10. Classification study of WISE infrared sources: identification of candidate asymptotic giant branch stars

    Institute of Scientific and Technical Information of China (English)

    Xun Tu; Zhong-Xiang Wang

    2013-01-01

    In the Wide-field Infrared Survey Explorer (WISE) all-sky source catalog there are 76 million mid-infrared point sources that were detected in the first three WISE bands and have association with only one 2MASS near-IR source within 3".We search for their identifications in the SIMBAD database and find 3.2 million identified sources.Based on these known sources,we establish three criteria for selecting candidate asymptotic giant branch (AGB) stars in the Galaxy,which are three defined zones in a color-color diagram,Galactic latitude |b| ≤ 20°,and "corrected" WISE third-band W3c≤ 11.Applying these criteria to the WISE+2MASS sources,1.37 million of them are selected.We analyze the WISE third-band W3 distribution of the selected sources,and further establish that W3≤8 is required in order to exclude a large fraction of normal stars from them.We therefore find 0.47 million candidate AGB stars in our Galaxy from the WISE source catalog.Using W3c,we estimate their distances and derive their Galactic distributions.The candidates are generally distributed around the Galactic center uniformly,with 68% (1-σ) of them within approximately 8 kpc.We discuss the idea that optical spectroscopy can be used to verify the C-rich AGB stars in our candidates,and thus a fraction of them (~10%) will be good targets for the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)survey that is planned to start in fall of 2012.

  11. Multi-band polarimetry of post-asymptotic giant branch stars - I. Optical measurements

    Science.gov (United States)

    Akras, S.; Ramírez Vélez, J. C.; Nanouris, N.; Ramos-Larios, G.; López, J. M.; Hiriart, D.; Panoglou, D.

    2017-04-01

    We present new optical broad-band (UBVRI) aperture polarimetric observations of 53 post-asymptotic giant branch (AGB) stars selected to exhibit a large near-infrared excess. 24 out of the 53 stars (45 per cent of our sample) are presented for the first time. A statistical analysis shows four distinctive groups of polarized post-AGB stars: unpolarized or very lowly polarized (degree of polarization or DoP 8 per cent). 23 out of the 53 (66 per cent) belong to the first group, 10 (19 per cent) to the second, five (9 per cent) to the third and only three (6 per cent) to the last group. Approximately 34 per cent of our sample was found to be unpolarized objects, which is close to the percentage of round planetary nebulae. On average, the low and moderate groups show a wavelength-dependent polarization that increases towards shorter wavelengths, implying an intrinsic origin of the polarization, which signifies a Rayleigh-like scattering spectrum typical for non-symmetrical envelopes composed principally of small dust grains. The moderately polarized stars exhibit higher K - W3 and W1 - W3 colour indices compared with the group of lowly polarized stars, suggesting a possible relation between DoP and mass-loss rate. Moreover, they are found to be systematically colder (redder in B - V), which may be associated with the condensation process close to these stars that results in a higher degree of polarization. We also provide evidence that multiple scattering in optically thin polar outflows is the mechanism that gives high DoP in post-AGB stars with bipolar or multi-polar envelopes.

  12. THE EFFECTS OF ROTATION ON s-PROCESS NUCLEOSYNTHESIS IN ASYMPTOTIC GIANT BRANCH STARS

    Energy Technology Data Exchange (ETDEWEB)

    Piersanti, L.; Cristallo, S.; Straniero, O., E-mail: piersanti@oa-teramo.inaf.it [INAF-Osservatorio Astronomico di Collurania, via Maggini snc, I-64100 Teramo (Italy)

    2013-09-10

    In this paper, we analyze the effects induced by rotation on low-mass asymptotic giant branch stars. We compute two sets of models, M = 2.0 M{sub Sun} at [Fe/H] = 0 and M = 1.5 M{sub Sun} at [Fe/H] = -1.7, by adopting main-sequence rotation velocities in the range 0-120 km s{sup -1}. At high metallicity, we find that the Goldreich-Schubert-Fricke instability, active at the interface between the convective envelope and the rapid rotating core, contaminates the {sup 13}C-pocket (the major neutron source) with {sup 14}N (the major neutron poison), thus reducing the neutron flux available for the synthesis of heavy elements. As a consequence, the yields of heavy-s elements (Ba, La, Nd, Sm) and, to a lesser extent, those of light-s elements (Sr, Y, Zr) decrease with increasing rotation velocities up to 60 km s{sup -1}. However, for larger initial rotation velocities, the production of light-s and, to a lesser extent, that of heavy-s, begins again to increase, due to mixing induced by meridional circulations. At low metallicity, the effects of meridional circulations are important even at rather low rotation velocity. The combined effect of the Goldreich-Schubert-Fricke instability and meridional circulations determines an increase of light-s and, to a lesser extent, heavy-s elements, while lead is strongly reduced. For both metallicities, the rotation-induced instabilities active during the interpulse phase reduce the neutron-to-seed ratio, so that the spectroscopic indexes [hs/ls] and [Pb/hs] decrease by increasing the initial rotation velocity. Our analysis suggests that rotation could explain the spread in the s-process indexes, as observed in s-process enriched stars at different metallicities.

  13. Hot Bottom Burning in Asymptotic Giant Branch Stars and the Turbulent Convection Model

    Science.gov (United States)

    D'Antona, Francesca; Mazzitelli, Italo

    1996-10-01

    We investigate the effect of two different local turbulent convection models on the structure of intermediate-mass stars (IMSs, 3.5 Msun ≤ M ≤7 Msun) in the asymptotic giant branch (AGB) phase where, according to observations, they should experience hot bottom burning (HBB). Evolutionary models adopting either the mixing length theory (MLT) or the Canuto & Mazzitelli (CM) description of stellar convection are discussed. It is found that, while the MLT structures require some degree of tuning to achieve, at the bottom of the convective envelope, the large temperatures required for HBB, the CM structures spontaneously achieve these conditions. Since the observational evidence for HBB (existence of a class of very luminous, lithium-rich AGB stars in the Magellanic Clouds showing low 12C/13C ratios) is quite compelling, the above result provides a further, successful test for the CM convective model, in stellar conditions far from solar. With the aid of the CM model, we then explore a number of problems related to the late evolution of this class of objects, and give first results for (1) the luminosity evolution of IMSs in the AGB phase (core mass-luminosity relation and luminosity range in which HBB occurs) for Population I and Population II structures, (2) the minimum core mass for semidegenerate carbon ignition (˜1.05 Msun), (3) the relation between initial mass and final white dwarf (WD) mass (also based on some observational evidences about the upper AGB stars), and (4) the expected mass function of massive WDs. Confirmation of the theoretical framework could arise from an observational test: the luminosity function of AGB stars is expected to show a gap at Mbol ˜ -6, which would distinguish between the low-luminosity regime, in which AGBs become carbon stars, and the upper luminosities, at which they undergo HBB, have very low 12C/13C ratios, and become lithium rich.

  14. The tip of the red giant branch as a distance indicator for resolved galaxies. 2: Computer simulations

    Science.gov (United States)

    Madore, Barry F.; Freedman, Wendy L.

    1995-01-01

    Based on both empirical data for the nearby galaxies, and on computer simulations, we show that measuring the position of the tip of the first-ascent red-giant branch provides a means of obtaining the distances to nearby galaxies with a precision and accuracy comparable to using Cepheids and/or RR Lyrae variables. We present an analysis of synthetic I vs (V-I) color magnitude diagrams of Population 2 systems to investigate the use of the observed discontinuity in the I-band luminosity function as a primary distance indicator. In the simulations we quantify the effects (1) signal to noise, (2) crowding, (3) population size, and (4) non-giant-branch-star contamination, on the method adopted for detecting the discontinuity,, measuring its luminosity, and estimating its uncertainity. We discuss sources of systematic error in the context of observable parameters, such as the signal-to-noise ratio and/or surface brightness. The simulations are then scaled to observed color-magnitude diagrams. It is concluded, that from the ground the tip of the red-giant-branch method can be sucessfully used to determine distances accurate to +/- 10% for galaxies out to 3 Mpc (mu approximately 27.5 mag); and from space a factor of four further in distance (mu approximately 30.6 mag) can be reached using HST. This method can be applied whereever a metal-poor population (-2.0 less than Z less than -0.7) of red-giant stars is detected (whose age is in the range 7-17 Gyr), whether that population resides in the halo of a spiral galaxy, the extended outer disk of a dwarf irregular, or in the outer periphery of an elliptical galaxy.

  15. Evolution of thermally pulsing asymptotic giant branch stars - I. The COLIBRI code

    Science.gov (United States)

    Marigo, Paola; Bressan, Alessandro; Nanni, Ambra; Girardi, Léo; Pumo, Maria Letizia

    2013-09-01

    We present the COLIBRI code for computing the evolution of stars along the thermally pulsing asymptotic giant branch (TP-AGB) phase. Compared to purely synthetic TP-AGB codes, COLIBRI relaxes a significant part of their analytic formalism in favour of a detailed physics applied to a complete envelope model, in which the stellar structure equations are integrated from the atmosphere down to the bottom of the hydrogen-burning shell. This allows us to predict self-consistently: (i) the effective temperature, and more generally the convective envelope and atmosphere structures, correctly coupled to the changes in the surface chemical abundances and gas opacities; (ii) the conditions under which sphericity effects may significantly affect the atmospheres of giant stars; (iii) the core mass-luminosity relation and its possible break-down due to the occurrence of hot-bottom burning (HBB) in the most massive AGB stars, by taking properly into account the nuclear energy generation in the H-burning shell and in the deepest layers of the convective envelope; (iv) the HBB nucleosynthesis via the solution of a complete nuclear network (including the pp chains, and the CNO, NeNa and MgAl cycles) coupled to a diffusive description of mixing, suitable to follow also the synthesis of 7Li via the Cameron-Fowler beryllium transport mechanism; (v) the intershell abundances left by each thermal pulse via the solution of a complete nuclear network applied to a simple model of the pulse-driven convective zone (PDCZ); (vi) the onset and quenching of the third dredge-up, with a temperature criterion that is applied, at each thermal pulse, to the result of envelope integrations at the stage of the post-flash luminosity peak. At the same time, COLIBRI pioneers new techniques in the treatment of the physics of stellar interiors, not yet adopted in full TP-AGB models. It is the first evolutionary code ever to use accurate on-the-fly computation of the equation of state (EoS) for roughly 800

  16. The puzzle of the CNO isotope ratios in asymptotic giant branch carbon stars

    Science.gov (United States)

    Abia, C.; Hedrosa, R. P.; Domínguez, I.; Straniero, O.

    2017-02-01

    Context. The abundance ratios of the main isotopes of carbon, nitrogen and oxygen are modified by the CNO-cycle in the stellar interiors. When the different dredge-up events mix the burning material with the envelope, valuable information on the nucleosynthesis and mixing processes can be extracted by measuring these isotope ratios. Aims: Previous determinations of the oxygen isotopic ratios in asymptotic giant branch (AGB) carbon stars were at odds with the existing theoretical predictions. We aim to redetermine the oxygen ratios in these stars using new spectral analysis tools and further develop discussions on the carbon and nitrogen isotopic ratios in order to elucidate this problem. Methods: Oxygen isotopic ratios were derived from spectra in the K-band in a sample of galactic AGB carbon stars of different spectral types and near solar metallicity. Synthetic spectra calculated in local thermodynamic equillibrium (LTE) with spherical carbon-rich atmosphere models and updated molecular line lists were used. The CNO isotope ratios derived in a homogeneous way, were compared with theoretical predictions for low-mass (1.5-3 M⊙) AGB stars computed with the FUNS code assuming extra mixing both during the RGB and AGB phases. Results: For most of the stars the 16O/17O/18O ratios derived are in good agreement with theoretical predictions confirming that, for AGB stars, are established using the values reached after the first dredge-up (FDU) according to the initial stellar mass. This fact, as far as the oxygen isotopic ratios are concerned, leaves little space for the operation of any extra mixing mechanism during the AGB phase. Nevertheless, for a few stars with large 16O/17O/18O, the operation of such a mechanism might be required, although their observed 12C/13C and 14N/15N ratios would be difficult to reconcile within this scenario. Furthermore, J-type stars tend to have lower 16O/17O ratios than the normal carbon stars, as already indicated in previous studies

  17. The "Tip" of the Red Giant Branch as a distance indicator theoretical calibration and the value of $H_0$

    CERN Document Server

    Cassisi, S

    1997-01-01

    Updated theoretical relations for the run of the bolometric and I magnitude of the Tip of the Red Giant Branch (TRGB) with respect to the metallicity are provided. An analogous relation for the V magnitude of the Zero Age Horizontal Branch at the RR Lyrae instability strip is also provided. A comparison has been performed among our ZAHB and TRGB distances, the Cepheid distance scale by Madore & Freedman (1991) and the HIPPARCOS distances set by local subdwarfs with accurate parallax determinations. The application of our TRGB distance scale to NGC3379 provides a distance to the Leo I group that is about 8% higher than the one obtained by Sakai et al. (1997) adopting the TRGB brightness calibration by Da Costa & Armandroff (1990). Our distance to the Leo I group, coupled with the relative distance Coma cluster-Leo I, provides a determination of H_0 at the Coma cluster: H_0=64_{-9}^{+10} Km s^{-1} Mpc^{-1}.

  18. The Distance to M101 Hosting Type Ia SN 2011fe Based on the Tip of the Red Giant Branch

    CERN Document Server

    Lee, Myung Gyoon

    2012-01-01

    We present a new determination of the distance to M101, host of the type Ia SN 2011fe, based on the tip of the red giant branch method (TRGB). Our determination is based on {\\it Hubble Space Telescope} archival $F555W$ and $F814W$ images of nine fields within the galaxy. Color-magnitude diagrams of arm-free regions in all fields show a prominent red giant branch (RGB). We measure the $I$-band magnitudes of the TRGB, obtaining a mean value of $I_{\\rm TRGB}=25.28\\pm0.01$ (where the error is a standard error), using an edge-detection method. We derive a weighted mean value of distance modulus $(m-M)_0=29.30\\pm0.01 ({\\rm random})\\pm0.12 ({\\rm systematic})$, corresponding to a linear distance of $7.24\\pm0.03\\pm0.40 $ Mpc. While previous estimates for M101 show a large range (TRGB distances of $(m-M)_0=29.05$ to 29.42 and Cepheid distances of $(m-M)_0=29.04$ to 29.71), our measurements of the TRGB distances for nine fields show a small dispersion of only 0.02. We combine our distance estimate and photometry in the ...

  19. The ACS Nearby Galaxy Survey Treasury IX. Constraining asymptotic giant branch evolution with old metal-poor galaxies

    CERN Document Server

    Girardi, Leo; Gilbert, Karoline M; Rosenfield, Philip; Dalcanton, Julianne J; Marigo, Paola; Boyer, Martha L; Dolphin, Andrew; Weisz, Daniel R; Melbourne, Jason; Olsen, Knut A G; Seth, Anil C; Skillman, Evan

    2010-01-01

    In an attempt to constrain evolutionary models of the asymptotic giant branch (AGB) phase at the limit of low masses and low metallicities, we have examined the luminosity functions and number ratio between AGB and red giant branch (RGB) stars from a sample of resolved galaxies from the ACS Nearby Galaxy Survey Treasury (ANGST). This database provides HST optical photometry together with maps of completeness, photometric errors, and star formation histories for dozens of galaxies within 4 Mpc. We select 12 galaxies characterized by predominantly metal-poor populations as indicated by a very steep and blue RGB, and which do not present any indication of recent star formation in their color--magnitude diagrams. Thousands of AGB stars brighter than the tip of the RGB (TRGB) are present in the sample (between 60 and 400 per galaxy), hence the Poisson noise has little impact in our measurements of the AGB/RGB ratio. We model the photometric data with a few sets of thermally pulsing AGB (TP-AGB) evolutionary models...

  20. NON-LOCAL THERMODYNAMICAL EQUILIBRIUM EFFECTS ON THE IRON ABUNDANCE OF ASYMPTOTIC GIANT BRANCH STARS IN 47 TUCANAE

    Energy Technology Data Exchange (ETDEWEB)

    Lapenna, E.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Massari, D. [Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Origlia, L. [INAF- Osservatorio Astronomico di Bologna, Via Ranzani, 1, 40127 Bologna (Italy)

    2014-12-20

    We present the iron abundance of 24 asymptotic giant branch (AGB) stars, members of the globular cluster 47 Tucanae, obtained with high-resolution spectra collected with the FEROS spectrograph at the MPG/ESO 2.2 m Telescope. We find that the iron abundances derived from neutral lines (with a mean value [Fe I/H] =–0.94 ± 0.01, σ = 0.08 dex) are systematically lower than those derived from single ionized lines ([Fe II/H] =–0.83 ± 0.01, σ = 0.05 dex). Only the latter are in agreement with those obtained for a sample of red giant branch (RGB) cluster stars, for which the Fe I and Fe II lines provide the same iron abundance. This finding suggests that non-local thermodynamical equilibrium (NLTE) effects driven by overionization mechanisms are present in the atmosphere of AGB stars and significantly affect the Fe I lines while leaving Fe II features unaltered. On the other hand, the very good ionization equilibrium found for RGB stars indicates that these NLTE effects may depend on the evolutionary stage. We discuss the impact of this finding on both the chemical analysis of AGB stars and on the search for evolved blue stragglers.

  1. The red giant branches of Galactic globular clusters in the [(V-I)o,Mv] plane metallicity indices and morphology

    CERN Document Server

    Saviane, I; Piotto, G; Aparicio, A; Saviane, Ivo; Rosenberg, Alfred; Piotto, Giampaolo; Aparicio, Antonio

    2000-01-01

    The purpose of this study is to carry out a thorough investigation of the changes in morphology of the red giant branch (RGB) of Galactic globular clusters (GGC) as a function of metallicity, in the V,I bands. To this aim, two key points are developed in the course of the analysis. (a) Using our photometric V,I database for Galactic globular clusters (the largest homogeneous data sample to date; Rosenberg et al. 1999) we measure a complete set of metallicity indices, based on the morphology and position of the red-giant branch. In particular, we provide here the first calibration of the S, DV_(1.1) and DV_(1.4) indices in the (V-I,V) plane. We show that our indices are internally consistent, and we calibrate each index in terms of metallicity, both on the Zinn & West (1984) and the Carretta & Gratton (1997) scales. Our new calibrations of the (V-I)o,g, DV_(1.2), (V-I)_(-3.0) and (V-I)_(-3.5) indices are consistent with existing relations. (b) Using a grid of selected RGB fiducial points, we define a f...

  2. The Large Magellanic Cloud as a laboratory for Hot Bottom Burning in massive Asymptotic Giant Branch stars

    CERN Document Server

    Ventura, P; Dell'Agli, F; Boyer, M L; García-Hernández, D A; Di Criscienzo, M; Schneider, R

    2015-01-01

    We use Spitzer observations of the rich population of Asymptotic Giant Branch stars in the Large Magellanic Cloud (LMC) to test models describing the internal structure and nucleosynthesis of the most massive of these stars, i.e. those with initial mass above $\\sim 4M_{\\odot}$. To this aim, we compare Spitzer observations of LMC stars with the theoretical tracks of Asymptotic Giant Branch models, calculated with two of the most popular evolution codes, that are known to differ in particular for the treatment of convection. Although the physical evolution of the two models are significantly different, the properties of dust formed in their winds are surprisingly similar, as is their position in the colour-colour (CCD) and colour-magnitude (CMD) diagrams obtained with the Spitzer bands. This model independent result allows us to select a well defined region in the ($[3.6]-[4.5], [5.8]-[8.0]$) plane, populated by AGB stars experiencing Hot Bottom Burning, the progeny of stars with mass $M\\sim 5.5M_{\\odot}$. This...

  3. Magnetic fields in single late-type giants in the Solar vicinity: How common is magnetic activity on the giant branches?

    CERN Document Server

    Konstantinova-Antova, R; Charbonnel, C; Drake, N A; Wade, G; Tsvetkova, S; Petit, P; Schröder, K -P; Lèbre, A

    2013-01-01

    We present our first results on a new sample containing all single G,K and M giants down to V = 4 mag in the Solar vicinity, suitable for spectropolarimetric (Stokes V) observations with Narval at TBL, France. For detection and measurement of the magnetic field (MF), the Least Squares Deconvolution (LSD) method was applied (Donati et al. 1997) that in the present case enables detection of large-scale MFs even weaker than the solar one (the typical precision of our longitudinal MF measurements is 0.1-0.2 G). The evolutionary status of the stars is determined on the basis of the evolutionary models with rotation (Lagarde et al. 2012; Charbonnel et al., in prep.) and fundamental parameters given by Massarotti et al. (1998). The stars appear to be in the mass range 1-4 M_sun, situated at different evolutionary stages after the Main Sequence (MS), up to the Asymptotic Giant Branch (AGB). The sample contains 45 stars. Up to now, 29 stars are observed (that is about 64 % of the sample), each observed at least twice....

  4. Effects of Alpha-Element Enhancement and the Thermally Pulsing-Asymptotic Giant Branch on Surface Brightness Fluctuation Magnitudes and Broadband Colors

    CERN Document Server

    Lee, Hyun-chul; Blakeslee, John P

    2009-01-01

    We investigate the effects of alpha-element enhancement and the thermally pulsing-asymptotic giant branch (TP-AGB) stars on the surface brightness fluctuation (SBF) magnitudes and broadband colors of simple stellar populations and compare to the empirical calibrations. We consider a broad range of ages and metallicities using the recently updated Teramo BaSTI isochrones. We find that the alpha-element enhanced I-band SBF magnitudes are brighter and their integrated V - I colors are redder, mostly because of oxygen enhancement effects on the upper red giant branch and asymptotic giant branch. The Teramo BaSTI and Padova isochrones that include TP-AGB stars fit the I-band and near-IR SBF empirical trends better than past models. Our results indicate that alpha-enhanced SBF models may be necessary to match red massive galaxies, while solar-scaled models may be adequate to match bluer galaxies.

  5. Naturally occurring branched-chain polyamines induce a crosslinked meshwork structure in a giant DNA

    Science.gov (United States)

    Muramatsu, Akira; Shimizu, Yuta; Yoshikawa, Yuko; Fukuda, Wakao; Umezawa, Naoki; Horai, Yuhei; Higuchi, Tsunehiko; Fujiwara, Shinsuke; Imanaka, Tadayuki; Yoshikawa, Kenichi

    2016-12-01

    We studied the effect of branched-chain polyamines on the folding transition of genome-sized DNA molecules in aqueous solution by the use of single-molecule observation with fluorescence microcopy. Detailed morphological features of polyamine/DNA complexes were characterized by atomic force microscopy (AFM). The AFM observations indicated that branched-chain polyamines tend to induce a characteristic change in the higher-order structure of DNA by forming bridges or crosslinks between the segments of a DNA molecule. In contrast, natural linear-chain polyamines cause a parallel alignment between DNA segments. Circular dichroism measurements revealed that branched-chain polyamines induce the A-form in the secondary structure of DNA, while linear-chain polyamines have only a minimum effect. This large difference in the effects of branched- and linear-chain polyamines is discussed in relation to the difference in the manner of binding of these polyamines to negatively charged double-stranded DNA.

  6. A New Giant Branch Clump Structure In the Large Magellanic Cloud

    CERN Document Server

    Piatti, A E; Bica, E; Claria, J J; Santos, J F C; Sarajedini, A; Dottori, H

    1999-01-01

    We present Washington C, T1 CCD photometry of 21 fields located in the northern part of the Large Magellanic Cloud (LMC), and spread over a region of more than 2.52 degrees approximately 6 degrees from the bar. The surveyed areas were chosen on the basis of their proximity to SL 388 and SL 509, whose fields showed the presence of a secondary giant clump, observationally detected by Bica et al. (1998, AJ, 116, 723). From the collected data we found that most of the observed field CMDs do not show a separate secondary clump, but rather a continuous vertical structure (VS), which is clearly seen for the first time. Its position and size are nearly the same throughout the surveyed regions: it lies below the Red Giant Clump (RGC) and extends from the bottom of the RGC to approximately 0.45 mag fainter, spanning the bluest color range of the RGC. The more numerous the VS stars in a field, the larger the number of LMC giants in the same zone. Our analysis demonstrate that VS stars belong to the LMC and are most like...

  7. STAR-TO-STAR IRON ABUNDANCE VARIATIONS IN RED GIANT BRANCH STARS IN THE GALACTIC GLOBULAR CLUSTER NGC 3201

    Energy Technology Data Exchange (ETDEWEB)

    Simmerer, Jennifer; Ivans, Inese I.; Filler, Dan [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Francois, Patrick [Paris-Meudon Observatory, France and Universite de Picardie Jules Verne, F-80080 Amiens (France); Charbonnel, Corinne [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, CH-1290 Versoix (Switzerland); Monier, Richard [Laboratoire Hippolyte Fizeau, Universite Nice Sophia Antipolis, Parc Valrose, F-06000 Nice (France); James, Gaeel, E-mail: jennifer@physics.utah.edu, E-mail: iii@physics.utah.edu, E-mail: dan.filler@utah.edu, E-mail: patrick.francois@obspm.fr, E-mail: corinne.charbonnel@unige.ch, E-mail: richard.monier@unice.fr, E-mail: gjames@eso.org [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Munchen (Germany)

    2013-02-10

    We present the metallicity as traced by the abundance of iron in the retrograde globular cluster NGC 3201, measured from high-resolution, high signal-to-noise spectra of 24 red giant branch stars. A spectroscopic analysis reveals a spread in [Fe/H] in the cluster stars at least as large as 0.4 dex. Star-to-star metallicity variations are supported both through photometry and through a detailed examination of spectra. We find no correlation between iron abundance and distance from the cluster core, as might be inferred from recent photometric studies. NGC 3201 is the lowest mass halo cluster to date to contain stars with significantly different [Fe/H] values.

  8. Galactic planetary nebulae with precise nebular abundances as a tool to understand the evolution of asymptotic giant branch stars

    CERN Document Server

    Garcia-Hernandez, D A; Delgado-Inglada, G; Dell'Agli, F; Di Criscienzo, M; Yagüe, A

    2016-01-01

    We present nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) models, with diffusive overshooting from all the convective borders, in the metallicity range Z/4 3.5 Msun) solar/supersolar metallicity AGBs that experience hot bottom burning (HBB), but other formation channels in low-mass AGBs like extra mixing, stellar rotation, binary interaction, or He pre-enrichment cannot be disregarded until more accurate C/O ratios would be obtained. Two objects among the DC PNe show the imprint of advanced CNO processing and deep second dredge-up, suggesting progenitors masses close to the limit to evolve as core collapse supernovae (above 6 Msun). Their actual C/O ratio, if confirmed, indicate contamination from the third dredge-up, rejecting the hypothesis that the chemical composition of such high-metallicity massive AGBs is modified exclusively by HBB.

  9. On Titanium Carbide Nanoparticles as the Origin of the 21 Micron Emission Feature in Post-Asymptotic Giant Branch Stars

    CERN Document Server

    Li, A

    2003-01-01

    Titanium carbide (TiC) nanocrystals were recently proposed as the carrier of the mysterious 21$\\mum$ emission feature observed in post-asymptotic giant branch stars, based on their close spectral match and the presolar nature of meteoritic TiC nanograins (which reveals their stellar ejecta origin). But we show in this {\\it Letter} that the Kramers-Kronig dispersion relations, which relate the wavelength-integrated extinction cross section to the total dust mass, would impose a lower bound on the TiC mass. This Kramers-Kronig lower limit exceeds the maximum available TiC mass by a factor of at least $\\simali$50, independent of the absolute value of the ultraviolet/visible absorptivity of nano TiC. The TiC model is therefore readily ruled out by the Kramers-Kronig physical principle.

  10. The Araucaria Project. On the Tip of the Red Giant Branch distance determination to the Magellanic Clouds

    CERN Document Server

    Gorski, Marek; Gieren, Wolfgang; Catelan, Marcio; Pilecki, Bogumil; Karczmarek, Paulina; Suchomska, Ksenia; Graczyk, Dariusz; Konorski, Piotr; Zgirski, Bartlomiej; Wielgorski, Piotr

    2016-01-01

    We present a precise optical and near-infrared determination of the Tip of the Red Giant Branch (TRGB) brightness in the Large and Small Magellanic Clouds (respectively LMC and SMC). The commonly used calibrations of the absolute magnitude of the TRGB lead to an overestimation of the distance to the LMC and SMC in the K band, and an underestimation of the distance in the optical I band for both galaxies. Reported discrepancies are at the level of 0.2 mag, with respect to the very accurate distance determinations to both Clouds based on late-type eclipsing binaries. The differential distances between the LMC and SMC obtained in the J and K bands, and for the bolometric brightness are consistent with each other, and with the results obtained from eclipsing binaries and other distance indicators.

  11. Differential chemical abundance analysis of a 47 Tucanæ asymptotic giant branch star with respect to Arcturus

    Science.gov (United States)

    Worley, C. C.; Cottrell, P. L.; Freeman, K. C.; Wylie-de Boer, E. C.

    2009-12-01

    This study resolves a discrepancy in the abundance of Zr in the 47 Tucanæ asymptotic giant branch (AGB) star Lee 2525. This star was observed using the echelle spectrograph on the 2.3-m telescope at Siding Spring Observatory. The analysis was undertaken by calibrating Lee 2525 with respect to the standard giant star Arcturus. This work emphasizes the importance of using a standard star with stellar parameters comparable to the star under analysis rather than a calibration with respect to the Sun as in Koch & McWilliam. Systematic errors in the analysis process are then minimized due to the similarity in atmospheric structure between the standard and programme stars. The abundances derived for Lee 2525 were found to be in general agreement with the Brown & Wallerstein values except for Zr. In this study Zr has a similar enhancement ([Zr/Fe] = +0.51 dex) to another light s-process element, Y ([Y/Fe] = +0.53 dex), which reflects current theory regarding the enrichment of s-process elements by nuclear processes within AGB stars. This is contrary to the results of Brown & Wallerstein where Zr was underabundant ([Zr/Fe] = -0.51 dex) and Y was overabundant ([Y/Fe] = +0.50 dex) with respect to Fe.

  12. Dust Production from Sub-Solar to Super-Solar Metallicity in Thermally Pulsing Asymptotic Giant Branch Stars

    Science.gov (United States)

    Nanni, A.; Bressan, A.; Marigo, P.; Girardi, L.; Javadi, A.; van Loon, J. Th.

    2015-08-01

    We discuss the dust chemistry and growth in the circumstellar envelopes (CSEs) of Thermally Pulsing Asymptotic Giant Branch (TP-AGB) star models, computed with the COLIBRI code, at varying initial mass and metallicity (Z = 0.001, 0.008, 0.02, 0.04, 0.06). A relevant result of our analysis deals with silicate production in M stars. We show that, in order to reproduce the observed trend between terminal velocities and mass-loss rates in Galactic M giants, one has to significantly reduce the efficiency of chemisputtering by H2 molecules, usually considered the most effective dust destruction mechanism. This conclusion is in agreement with the most recent laboratory results, which show that silicates may condense already at Tcond˜1400 K, rather than only at Tcond˜1000 K, as obtained by models that include chemisputtering. From analysis of the total dust ejecta, we find that the dust-to-gas ratios of the total ejecta from intermediate-mass stars are much less dependent on metallicity than usually assumed. In a broader context, our results are suitable for studying the dust enrichment of the interstellar medium provided by TP-AGB stars in both nearby and high-redshift galaxies.

  13. Dust production from sub-solar to super-solar metallicity in Thermally Pulsing Asymptotic Giant Branch Stars

    CERN Document Server

    Ambra, Nanni; Paola, Marigo; Léo, Girardi; Atefeh, Javadi; Jacco, van Loon

    2014-01-01

    We discuss the dust chemistry and growth in the circumstellar envelopes (CSEs) of Thermally Pulsing Asymptotic Giant Branch (TP-AGB) star models computed with the COLIBRI code, at varying initial mass and metallicity (Z=0.001, 0.008, 0.02, 0.04, 0.06). A relevant result of our analysis deals with the silicate production in M-stars. We show that, in order to reproduce the observed trend between terminal velocities and mass-loss rates in Galactic M-giants, one has to significantly reduce the efficiency of chemisputtering by H2 molecules, usually considered as the most effective dust destruction mechanism. This indication is also in agreement with the most recent laboratory results, which show that silicates may condense already at T=1400 K, instead than at Tcond=1000 K, as obtained by models that include chemisputtering. From the analysis of the total dust ejecta, we find that the total dust-to-gas ejecta of intermediate-mass stars are much less dependent on metallicity than usually assumed. In a broader contex...

  14. The red giant branch phase transition: Implications for the RGB luminosity function bump and detections of Li-rich red clump stars

    CERN Document Server

    Cassisi, Santi; Pietrinferni, Adriano

    2015-01-01

    We performed a detailed study of the evolution of the luminosity of He-ignition stage and of the red giant branch bump luminosity during the red giant branch phase transition for various metallicities. To this purpose we calculated a grid of stellar models that sample the mass range of the transition with a fine mass step equal to ${\\rm 0.01M_\\odot}$. We find that for a stellar population with a given initial chemical composition, there is a critical age (of 1.1-1.2~Gyr) around which a decrease in age of just 20-30 million years causes a drastic drop in the red giant branch tip brightness. We also find a narrow age range (a few $10^7$ yr) around the transition, characterized by the luminosity of the red giant branch bump being brighter than the luminosity of He ignition. We discuss a possible link between this occurrence and observations of Li-rich core He-burning stars.

  15. Mass loss on the red giant branch: the value and metallicity dependence of Reimers' {\\eta} in globular clusters

    CERN Document Server

    McDonald, Iain

    2015-01-01

    The impact of metallicity on the mass-loss rate from red giant branch (RGB) stars is studied through its effect on the parameters of horizontal branch (HB) stars. The scaling factors from Reimers (1975) and Schroder & Cuntz (2005) are determined for 56 well-studied Galactic globular clusters (GCs). The median values among clusters are, respectively, {\\eta}_R = 0.477 +/- 0.070 (+0.050/-0.062) and {\\eta}_SC = 0.172 +/- 0.024 (+0.018/-0.023) (standard deviation and systematic uncertainties, respectively). Mass-loss mechanisms on the RGB have very little metallicity dependence: over a factor of 200 in iron abundance, {\\eta} varies by <~30 per cent, within the current systematic uncertainties on cluster ages and evolution models. Since {\\eta} incorporates cluster age, the low standard deviation of {\\eta} among clusters (~14 per cent) suggests that age can almost entirely account for the "second parameter problem". The remaining spread in {\\eta} correlates with cluster mass and density, suggesting helium enr...

  16. Lithium abundance in the globular cluster M4: from the turn-off to the red giant branch bump

    Science.gov (United States)

    Mucciarelli, A.; Salaris, M.; Lovisi, L.; Ferraro, F. R.; Lanzoni, B.; Lucatello, S.; Gratton, R. G.

    2011-03-01

    We present Li and Fe abundances for 87 stars in the globular cluster M4, obtained by using high-resolution spectra collected with GIRAFFE at the Very Large Telescope. The targets range from the turn-off up to the red giant branch bump. The Li abundance in the turn-off stars is uniform, with an average value equal to A(Li)= 2.30 ± 0.02 dex (σ= 0.10 dex), consistent with the upper envelope of Li content measured in other globular clusters and in the halo field stars, confirming also for M4 the discrepancy with the primordial Li abundance predicted by Wilkinson Microwave Anisotropy Probe+ big bang nucleosynthesis (WMAP+BBNS). The global behaviour of A(Li) as a function of the effective temperature allows us to identify the two main drops in the Li evolution due to the first dredge-up and to the extra-mixing episode after the red giant branch bump. The measured iron content of M4 results to [Fe/H]=-1.10 ± 0.01 dex (σ= 0.07 dex), with no systematic offsets between dwarf and giant stars. The behaviour of the Li and Fe abundances along the entire evolutionary path is incompatible with theoretical models including pure atomic diffusion, pointing out that an additional turbulent mixing below the convective region needs to be taken into account, able to inhibit the atomic diffusion. The measured value of A(Li) and its homogeneity in the turn-off stars allow us to put strong constraints on the shape of the Li profile inside the M4 turn-off stars. The global behaviour of A(Li) with the effective temperature can be reproduced with different pristine Li abundances, depending on the kind of adopted turbulent mixing. One cannot reproduce the global trend that starts from the WMAP+BBNS A(Li) and adopts the turbulent mixing described by Richard, Michaud & Richer with the same efficiency as that used by Korn et al. to explain the Li content in NGC 6397. In fact, such a solution is not able to well reproduce simultaneously the Li abundance observed in turn-off and red giant branch

  17. THE INSIDIOUS BOOSTING OF THERMALLY PULSING ASYMPTOTIC GIANT BRANCH STARS IN INTERMEDIATE-AGE MAGELLANIC CLOUD CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Girardi, Léo [Osservatorio Astronomico di Padova-INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Marigo, Paola [Dipartimento di Fisica e Astronomia Galileo Galilei, Università di Padova, Vicolo dell' Osservatorio 3, I-35122 Padova (Italy); Bressan, Alessandro [SISSA, via Bonomea 365, I-34136 Trieste (Italy); Rosenfield, Philip [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)

    2013-11-10

    In the recent controversy about the role of thermally pulsing asymptotic giant branch (TP-AGB) stars in evolutionary population synthesis (EPS) models of galaxies, one particular aspect is puzzling: TP-AGB models aimed at reproducing the lifetimes and integrated fluxes of the TP-AGB phase in Magellanic Cloud (MC) clusters, when incorporated into EPS models, are found to overestimate, to various extents, the TP-AGB contribution in resolved star counts and integrated spectra of galaxies. In this paper, we call attention to a particular evolutionary aspect, linked to the physics of stellar interiors, that in all probability is the main cause of this conundrum. As soon as stellar populations intercept the ages at which red giant branch stars first appear, a sudden and abrupt change in the lifetime of the core He-burning phase causes a temporary 'boost' in the production rate of subsequent evolutionary phases, including the TP-AGB. For a timespan of about 0.1 Gyr, triple TP-AGB branches develop at slightly different initial masses, causing their frequency and contribution to the integrated luminosity of the stellar population to increase by a factor of ∼2. The boost occurs for turn-off masses of ∼1.75 M{sub ☉}, just in the proximity of the expected peak in the TP-AGB lifetimes (for MC metallicities), and for ages of ∼1.6 Gyr. Coincidently, this relatively narrow age interval happens to contain the few very massive MC clusters that host most of the TP-AGB stars used to constrain stellar evolution and EPS models. This concomitance makes the AGB-boosting particularly insidious in the context of present EPS models. As we discuss in this paper, the identification of this evolutionary effect brings about three main consequences. First, we claim that present estimates of the TP-AGB contribution to the integrated light of galaxies derived from MC clusters are biased toward too large values. Second, the relative TP-AGB contribution of single-burst populations

  18. The stellar spectral features of nearby galaxies in the near infrared: tracers of thermally pulsing asymptotic giant branch stars?

    Science.gov (United States)

    Riffel, Rogério; Mason, Rachel E.; Martins, Lucimara P.; Rodríguez-Ardila, Alberto; Ho, Luis C.; Riffel, Rogemar A.; Lira, Paulina; Gonzalez Martin, Omaira; Ruschel-Dutra, Daniel; Alonso-Herrero, Almudena; Flohic, Helene; McDermid, Richard M.; Ramos Almeida, Cristina; Thanjavur, Karun; Winge, Claudia

    2015-07-01

    We analyse the stellar absorption features in high signal-to-noise ratio (S/N) near-infrared (NIR) spectra of the nuclear region of 12 nearby galaxies, mostly spirals. The features detected in some or all of the galaxies in this sample are the TiO (0.843 and 0.886 μm), VO (1.048 μm), CN (1.1 and 1.4 μm), H2O (1.4 and 1.9 μm) and CO (1.6 and 2.3 μm) bands. The C2 (1.17 and 1.76 μm) bands are generally weak or absent, although C2 (1.76 μm) may be weakly present in the mean galaxy spectrum. A deep feature near 0.93 μm, likely caused by CN, TiO and/or ZrO, is also detected in all objects. Fitting a combination of stellar spectra to the mean spectrum shows that the absorption features are produced by evolved stars: cool giants and supergiant stars in the early- or thermally pulsing asymptotic giant branch (E-AGB or TP-AGB) phases. The high luminosity of TP-AGB stars, and the appearance of VO and ZrO features in the data, suggest that TP-AGB stars dominate these spectral features. However, a contribution from other evolved stars is also likely. Comparison with evolutionary population synthesis models shows that models based on empirical libraries that predict relatively strong NIR features provide a more accurate description of the data. However, none of the models tested accurately reproduces all of the features observed in the spectra. To do so, the models will need to not only improve the treatment of TP-AGB stars, but also include good quality spectra of red giant and E-AGB stars. The uninterrupted wavelength coverage, high S/N and quantity of features we present here will provide a benchmark for the next generation of models aiming to explain and predict the NIR properties of galaxies.

  19. Nucleosynthesis in helium-enriched asymptotic giant branch models: Implications for Heavy Element Enrichment in Omega Centauri

    CERN Document Server

    Karakas, Amanda I; Nataf, David M

    2014-01-01

    We investigate the effect of helium enrichment on the evolution and nucleosynthesis of low-mass asymptotic giant branch (AGB) stars of 1.7Msun and 2.36Msun with a metallicity of Z=0.0006 ([Fe/H] = -1.4). We calculate evolutionary sequences with the primordial helium abundance (Y = 0.24) and with helium-enriched compositions (Y = 0.30, 0.35, 0.40). For comparison we calculate models of the same mass but at a lower metallicity Z=0.0003 ([Fe/H] = -1.8) with Y=0.24. Post-processing nucleosynthesis calculations are performed on each of the evolutionary sequences to determine the production of elements from hydrogen through to bismuth. Elemental surface abundance predictions and stellar yields are presented for each model. The models with enriched helium have shorter main sequence and AGB lifetimes, and enter the AGB with a more massive hydrogen exhausted core than the primordial helium model. The main consequences are 1) low-mass AGB models with enhanced helium will evolve more than twice as fast, giving them the ...

  20. Revisiting the role of the Thermally-Pulsating Asymptotic Giant Branch phase in high-redshift galaxies

    CERN Document Server

    Capozzi, Diego; Daddi, Emanuele; Renzini, Alvio; Strazzullo, Veronica; Gobat, Raphael

    2015-01-01

    We study the debated contribution from thermally pulsing asymptotic giant branch (TP-AGB) stars in evolutionary population synthesis models. We investigate the Spectral Energy Distributions (SEDs) of a sample of 51 spectroscopically confirmed, high-z ($1.3

  1. New models for the evolution of Post-Asymptotic Giant Branch stars and Central Stars of Planetary Nebulae

    CERN Document Server

    Bertolami, Marcelo M Miller

    2015-01-01

    The Post Asymptotic Giant Branch (AGB) phase is arguably one of the least understood phases of the evolution of low- and intermediate- mass stars. The two grids of models presently available are based on outdated micro- and macro-physics and do not agree with each other. We study the timescales of post-AGB and CSPNe in the context of our present understanding of the micro- and macro-physics of stars. We want to assess whether new post-AGB models, based on the latter improvements in TP-AGB modeling, can help to understand the discrepancies between observation and theory and within theory itself. We compute a grid of post-AGB full evolutionary sequences that include all previous evolutionary stages from the Zero Age Main Sequence to the White Dwarf phase. Models are computed for initial masses between 0.8 and 4 $M_\\odot$ and for a wide range of initial metallicities ($Z_0=$0.02, 0.01, 0.001, 0.0001), this allow us to provide post-AGB timescales and properties for H-burning post-AGB objects with masses in the re...

  2. Galactic planetary nebulae with precise nebular abundances as a tool to understand the evolution of asymptotic giant branch stars

    Science.gov (United States)

    García-Hernández, D. A.; Ventura, P.; Delgado-Inglada, G.; Dell'Agli, F.; Di Criscienzo, M.; Yagüe, A.

    2016-09-01

    We present nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) models, with diffusive overshooting from all the convective borders, in the metallicity range Z⊙/4 chemical pattern similar to the DC PNe. In agreement with recent literature, the DC PNe mostly descend from high-mass (M ≥ 3.5 M⊙) solar/supersolar metallicity AGBs that experience hot bottom burning (HBB), but other formation channels in low-mass AGBs like extra mixing, stellar rotation, binary interaction, or He pre-enrichment cannot be disregarded until more accurate C/O ratios would be obtained. Two objects among the DC PNe show the imprint of advanced CNO processing and deep second dredge-up, suggesting progenitors masses close to the limit to evolve as core collapse supernovae (above 6M⊙). Their actual C/O ratio, if confirmed, indicate contamination from the third dredge-up, rejecting the hypothesis that the chemical composition of such high-metallicity massive AGBs is modified exclusively by HBB.

  3. The Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters NGC 6342 and NGC 6366

    CERN Document Server

    Johnson, Christian I; Rich, R Michael; Pilachowski, Catherine A; Hsyu, Tiffany

    2016-01-01

    We present radial velocities and chemical abundances for red giant branch stars in the Galactic bulge globular clusters NGC 6342 and NGC 6366. The velocities and abundances are based on measurements of high resolution (R > 20,000) spectra obtained with the MMT-Hectochelle and WIYN-Hydra spectrographs. We find that NGC 6342 has a heliocentric radial velocity of +112.5 km/s (sigma = 8.6 km/s), NGC 6366 has a heliocentric radial velocity of -122.3 km/s (sigma = 1.5 km/s), and that both clusters have nearly identical metallicities ([Fe/H] ~ -0.55). NGC 6366 shows evidence of a moderately extended O-Na anti-correlation, but more data are needed for NGC 6342 to determine if this cluster also exhibits the typical O-Na relation likely found in all other Galactic globular clusters. The two clusters are distinguished from similar metallicity field stars as having larger [Na/Fe] spreads and enhanced [La/Fe] ratios, but we find that NGC 6342 and NGC 6366 display alpha and Fe-peak element abundance patterns that are typic...

  4. The Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters NGC 6342 and NGC 6366

    Science.gov (United States)

    Johnson, Christian I.; Caldwell, Nelson; Rich, R. Michael; Pilachowski, Catherine A.; Hsyu, Tiffany

    2016-07-01

    We present radial velocities and chemical abundances for red giant branch stars in the Galactic bulge globular clusters NGC 6342 and NGC 6366. The velocities and abundances are based on measurements of high-resolution (R ≳ 20,000) spectra obtained with the MMT-Hectochelle and WIYN-Hydra spectrographs. We find that NGC 6342 has a heliocentric radial velocity of +112.5 km s-1 (σ = 8.6 km s-1), NGC 6366 has a heliocentric radial velocity of -122.3 km s-1 (σ = 1.5 km s-1), and both clusters have nearly identical metallicities ([Fe/H] ≈ -0.55). NGC 6366 shows evidence of a moderately extended O-Na anti-correlation, but more data are needed for NGC 6342 to determine if this cluster also exhibits the typical O-Na relation likely found in all other Galactic globular clusters. The two clusters are distinguished from similar metallicity field stars as having larger [Na/Fe] spreads and enhanced [La/Fe] ratios, but we find that NGC 6342 and NGC 6366 display α and Fe-peak element abundance patterns that are typical of other metal-rich ([Fe/H] > -1) inner Galaxy clusters. However, the median [La/Fe] abundance may vary from cluster-to-cluster.

  5. On the Interpretation of Sub-Giant Branch Morphologies of Intermediate-Age Star Clusters with Extended Main Sequence Turnoffs

    CERN Document Server

    Goudfrooij, Paul; Rosenfield, Philip; Bressan, Alessandro; Marigo, Paola; Correnti, Matteo; Puzia, Thomas H

    2015-01-01

    Recent high-quality photometry of many star clusters in the Magellanic Clouds with ages of 1$\\,-\\,$2 Gyr revealed main sequence turnoffs (MSTOs) that are significantly wider than can be accounted for by a simple stellar population (SSP). Such extended MSTOs (eMSTOs) are often interpreted in terms of an age spread of several $10^8$ yr, challenging the traditional view of star clusters as being formed in a single star formation episode. Li et al. and Bastian & Niederhofer recently investigated the sub-giant branches (SGBs) of NGC 1651, NGC 1806, and NGC 1846, three star clusters in the Large Magellanic Cloud (LMC) that exhibit an eMSTO. They argued that the SGB of these star clusters can be explained only by a SSP. We study these and two other similar star clusters in the LMC, using extensive simulations of SSPs including unresolved binaries. We find that the shapes of the cross-SGB profiles of all star clusters in our sample are in fact consistent with their cross-MSTO profiles when the latter are interpre...

  6. Carbon-rich dust past the asymptotic giant branch: aliphatics, aromatics, and fullerenes in the Magellanic Clouds

    CERN Document Server

    Sloan, G C; Zijlstra, A A; Kraemer, K E; Weis, A P; Matsuura, M; Volk, K; Peeters, E; Duley, W W; Cami, J; Bernard-Salas, J; Kemper, F; Sahai, R

    2014-01-01

    Infrared spectra of carbon-rich objects which have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 um emission feature. To test for the presence of fullerenes, we used the position and width of the feature at 18.7-18.9 um and examined other features at 17.4 and 6-9 um. This method adds three new fullerene sources to the known sample, but it also calls into question three previous identifications. We confirm that the strong 11 um features seen in some sources arise primarily from SiC, which may exist as a coating around carbonaceous cores and result from photo-processing. Spectra showing the 21 um feature usually show the newly defined Class D PAH profile at 7-9 um. These spectra exhibit unusual PAH profiles at 11-14 um, with weak contributions at 12.7 um, which we define as Class D1, or show features shifted to ~11.4, 12.4, and 13.2 um, which we ...

  7. On the metallicity dependence of crystalline silicates in oxygen-rich asymptotic giant branch stars and red supergiants

    CERN Document Server

    Jones, O C; Sargent, B A; McDonald, I; Gielen, C; Woods, Paul M; Sloan, G C; Boyer, M L; Zijlstra, A A; Clayton, G C; Kraemer, K E; Srinivasan, S; Ruffle, P M E

    2012-01-01

    We investigate the occurrence of crystalline silicates in oxygen-rich evolved stars across a range of metallicities and mass-loss rates. It has been suggested that the crystalline silicate feature strength increases with increasing mass-loss rate, implying a correlation between lattice structure and wind density. To test this, we analyse Spitzer IRS and Infrared Space Observatory SWS spectra of 217 oxygen-rich asymptotic giant branch stars and 98 red supergiants in the Milky Way, the Large and Small Magellanic Clouds and Galactic globular clusters. These encompass a range of spectral morphologies from the spectrally-rich which exhibit a wealth of crystalline and amorphous silicate features to 'naked' (dust-free) stars. We combine spectroscopic and photometric observations with the GRAMS grid of radiative transfer models to derive (dust) mass-loss rates and temperature. We then measure the strength of the crystalline silicate bands at 23, 28 and 33 microns. We detect crystalline silicates in stars with dust ma...

  8. Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies

    CERN Document Server

    Tolstoy, E; Cole, A A; Pasquini, L; Gilmozzi, R; Gallagher, J S; Tolstoy, Eline; Irwin, Michael J.; Cole, Andrew A.

    2001-01-01

    Spectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to unambiguously determine the evolutionary histories of galaxies. Using FORS1 in Multi-Object Spectroscopy mode on ANTU (UT1) at the ESO-VLT on Paranal we obtained near infrared spectra from which we measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of Red Giant Branch stars, selected from ESO-NTT optical (I, V-I) photometry of three nearby, Local Group, galaxies: the Sculptor Dwarf Spheroidal, the Fornax Dwarf Spheroidal and the Dwarf Irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption line feature, centered at 8500A, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991) and Rutledge, Hesser & Stetson (1997). We measured metallicities for 37 stars in Sculptor, 32 stars in Fornax, and 23 stars in NGC 6822, yie...

  9. Evolution of asymptotic giant branch stars II. Optical to far-infrared isochrones with improved TP-AGB models

    CERN Document Server

    Marigo, Paola; Bressan, Alessandro; Groenewegen, Martin A T; Silva, Laura; Granato, Gian Luigi

    2007-01-01

    We present a large set of theoretical isochrones, whose distinctive features mostly reside on the greatly improved treatment of the thermally pulsing asymptotic giant branch (TP-AGB) phase. Essentially, we have coupled the TP-AGB tracks described in Paper I, at their stages of pre-flash quiescent H-shell burning, with the evolutionary tracks for the previous evolutionary phases from Girardi et al. (2000). Theoretical isochrones for any intermediate value of age and metallicity are then derived by interpolation in the grids. We take care that the isochrones keep, to a good level of detail, the several peculiarities present in these TP-AGB tracks. Theoretical isochrones are then converted to about 20 different photometric systems -- including traditional ground-based systems, and those of recent major wide-field surveys such as SDSS, OGLE, DENIS, 2MASS, UKIDSS, etc., -- by means of synthetic photometry applied to an updated library of stellar spectra, suitably extended to include C-type stars. Finally, we corre...

  10. Spectroscopy and Photometry of Multiple Populations along the Asymptotic Giant Branch of NGC 2808 and NGC 6121 (M4)

    Science.gov (United States)

    Marino, A. F.; Milone, A. P.; Yong, D.; Da Costa, G.; Asplund, M.; Bedin, L. R.; Jerjen, H.; Nardiello, D.; Piotto, G.; Renzini, A.; Shetrone, M.

    2017-07-01

    We present a photometric and spectroscopic study of multiple populations along the asymptotic giant branch (AGB) of the intermediate-metallicity globular clusters (GCs) NGC 2808 and NGC 6121 (M4). Chemical abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Co, Ni, Zn, Y, and Ce in AGB stars from high-resolution FLAMES+UVES@VLT spectra are reported for both clusters. Our spectroscopic results have been combined with multiwavelength photometry from the Hubble Space Telescope UV survey of Galactic GCs and ground-based photometry, as well as proper motions derived by combining stellar positions from ground-based images and Gaia DR1. Our analysis reveals that the AGBs of both clusters host multiple populations with different chemical compositions. In M4, we have identified two main populations of stars with different Na/O content lying on distinct AGBs in the {m}{{F}438{{W}}} versus {C}{{F}275{{W}},{{F}}336{{W}},{{F}}438{{W}}} and the V versus {C}{{U},{{B}},{{I}}} pseudo-color-magnitude diagrams. In the more massive and complex GC NGC 2808, three groups of stars with different chemical abundances occupy different locations on the so-called “chromosome map” photometric diagram constructed for AGB stars. The spectroscopic + photometric comparison of stellar populations along the AGB and the red giants of this GC suggests that the AGB hosts stellar populations with a range in helium abundances from primordial to high contents of Y˜ 0.32. By contrast, from our data set, there is no evidence for stars with extreme helium abundance (Y˜ 0.38) on the AGB, suggesting that the most He-rich stars of NGC 2808 do not reach this phase. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 093.D-0789 and 094.D-0455 and on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  11. Carbon-rich dust past the asymptotic giant branch: Aliphatics, aromatics, and fullerenes in the Magellanic Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Sloan, G. C.; Lagadec, E. [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853-6801 (United States); Zijlstra, A. A. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Kraemer, K. E. [Institute for Scientific Research, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Weis, A. P. [Department of Astronomy and Astrophysics, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Matsuura, M. [Astrophysics Group, Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Volk, K. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Peeters, E.; Cami, J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Duley, W. W. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Bernard-Salas, J. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); Kemper, F. [Academia Sinica, Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, NTU/AS, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, R.O.C (China); Sahai, R., E-mail: sloan@isc.astro.cornell.edu [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States)

    2014-08-10

    Infrared spectra of carbon-rich objects that have evolved off the asymptotic giant branch reveal a range of dust properties, including fullerenes, polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and several unidentified features, including the 21 μm emission feature. To test for the presence of fullerenes, we used the position and width of the feature at 18.7-18.9 μm and examined other features at 17.4 and 6-9 μm. This method adds three new fullerene sources to the known sample, but it also calls into question three previous identifications. We confirm that the strong 11 μm features seen in some sources arise primarily from SiC, which may exist as a coating around carbonaceous cores and result from photo-processing. Spectra showing the 21 μm feature usually show the newly defined Class D PAH profile at 7-9 μm. These spectra exhibit unusual PAH profiles at 11-14 μm, with weak contributions at 12.7 μm, which we define as Class D1, or show features shifted to ∼11.4, 12.4, and 13.2 μm, which we define as Class D2. Alkyne hydrocarbons match the 15.8 μm feature associated with 21 μm emission. Sources showing fullerene emission but no PAHs have blue colors in the optical, suggesting a clear line of sight to the central source. Spectra with 21 μm features and Class D2 PAH emission also show photometric evidence for a relatively clear line of sight to the central source. The multiple associations of the 21 μm feature with aliphatic hydrocarbons suggest that the carrier is related to this material in some way.

  12. THE DUST BUDGET OF THE SMALL MAGELLANIC CLOUD: ARE ASYMPTOTIC GIANT BRANCH STARS THE PRIMARY DUST SOURCE AT LOW METALLICITY?

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, M. L.; Gordon, K. D.; Meixner, M.; Sargent, B. A. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Srinivasan, S. [UPMC-CNRS UMR7095, Institut d' Astrophysique de Paris, F-75014 Paris (France); Riebel, D. [Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); McDonald, I. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Van Loon, J. Th. [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom); Clayton, G. C. [Department of Physics and Astronomy, Louisiana State University, 233-A Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States); Sloan, G. C., E-mail: mboyer@stsci.edu [Astronomy Department, Cornell University, Ithaca, NY 14853-6801 (United States)

    2012-03-20

    We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud, using the 8 {mu}m excess emission as a proxy for the dust-production rate (DPR). We find that asymptotic giant branch (AGB) and red supergiant (RSG) stars produce (8.6-9.5) Multiplication-Sign 10{sup -7} M{sub Sun} yr{sup -1} of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%-50% uncertainty in individual DPRs). RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called extreme AGB stars) account for 87%-89% of the total dust input from cool evolved stars. We also estimate the dust input from hot stars and supernovae (SNe), and find that if SNe produce 10{sup -3} M{sub Sun} of dust each, then the total SN dust input and AGB input are roughly equivalent. We consider several scenarios of SN dust production and destruction and find that the interstellar medium (ISM) dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. We find that AGB stars contribute only 2.1% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggests that dust must grow in the ISM or be formed by another unknown mechanism.

  13. On the interpretation of sub-giant branch morphologies of intermediate-age star clusters with extended main sequence turnoffs

    Science.gov (United States)

    Goudfrooij, Paul; Girardi, Léo; Rosenfield, Philip; Bressan, Alessandro; Marigo, Paola; Correnti, Matteo; Puzia, Thomas H.

    2015-06-01

    High-quality photometry of many star clusters in the Magellanic Clouds with ages of 1-2 Gyr revealed main sequence turnoffs (MSTOs) that are significantly wider than can be accounted for by a simple stellar population (SSP). Such extended MSTOs (eMSTOs) are often interpreted in terms of an age spread of several 108 yr, challenging the traditional view of star clusters as being formed in a single star formation episode. Li et al. and Bastian & Niederhofer recently investigated the sub-giant branches (SGBs) of NGC 1651, NGC 1806, and NGC 1846, three star clusters in the Large Magellanic Cloud (LMC) that exhibit an eMSTO. They argued that the SGB of these star clusters can be explained only by an SSP. We study these and two other similar star clusters in the LMC, using extensive simulations of SSPs including unresolved binaries. We find that the shapes of the cross-SGB profiles of all star clusters in our sample are in fact consistent with their cross-MSTO profiles when the latter are interpreted as age distributions. Conversely, SGB morphologies of star clusters with eMSTOs are found to be inconsistent with those of simulated SSPs. Finally, we create PARSEC isochrones from tracks featuring a grid of convective overshoot levels and a very fine grid of stellar masses. A comparison of the observed photometry with these isochrones shows that the morphology of the red clump (RC) of such star clusters is also consistent with that implied by their MSTO in the age spread scenario. We conclude that the SGB and RC morphologies of star clusters featuring eMSTOs are consistent with the scenario in which the eMSTOs are caused by a distribution of stellar ages.

  14. Connecting the evolution of thermally pulsing asymptotic giant branch stars to the chemistry in their circumstellar envelopes - I. Hydrogen cyanide

    Science.gov (United States)

    Marigo, Paola; Ripamonti, Emanuele; Nanni, Ambra; Bressan, Alessandro; Girardi, Léo

    2016-02-01

    We investigate the formation of hydrogen cyanide (HCN) in the inner circumstellar envelopes of thermally pulsing asymptotic giant branch (TP-AGB) stars. A dynamic model for periodically shocked atmospheres, which includes an extended chemo-kinetic network, is for the first time coupled to detailed evolutionary tracks for the TP-AGB phase computed with the COLIBRI code. We carried out a calibration of the main shock parameters (the shock formation radius rs,0 and the effective adiabatic index γ _ad^eff) using the circumstellar HCN abundances recently measured for a populous sample of pulsating TP-AGB stars. Our models recover the range of the observed HCN concentrations as a function of the mass-loss rates, and successfully reproduce the systematic increase of HCN moving along the M-S-C chemical sequence of TP-AGB stars, which traces the increase of the surface C/O ratio. The chemical calibration brings along two important implications for the physical properties of the pulsation-induced shocks: (i) the first shock should emerge very close to the photosphere (rs,0 ≃ 1R), and (ii) shocks are expected to have a dominant isothermal character (γ _ad^eff˜eq 1) in the denser region close to the star (within ˜3-4R), implying that radiative processes should be quite efficient. Our analysis also suggests that the HCN concentrations in the inner circumstellar envelopes are critically affected by the H-H2 chemistry during the post-shock relaxation stages. Given the notable sensitiveness of the results to stellar parameters, this paper shows that such chemo-dynamic analyses may indeed provide a significant contribution to the broader goal of attaining a comprehensive calibration of the TP-AGB evolutionary phase.

  15. Barium isotopic composition of mainstream silicon carbides from Murchison: Constraints for s-process nucleosynthesis in asymptotic giant branch stars

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Nan; Davis, Andrew M.; Pellin, Michael J.; Dauphas, Nicolas [Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637 (United States); Savina, Michael R. [Chicago Center for Cosmochemistry, Chicago, IL 60637 (United States); Gallino, Roberto; Bisterzo, Sara [Dipartimento di Fisica, Università di Torino, I-10125 Torino (Italy); Straniero, Oscar; Cristallo, Sergio [INAF–Osservatorio Astronomico di Collurania, via Maggini snc, I-64100 Teramo (Italy); Gyngard, Frank [Laboratory for Space Sciences, Washington University, St. Louis, MO 63130 (United States); Willingham, David G. [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Pignatari, Marco [Department of Physics, University of Basel, Basel CH-4056 (Switzerland); Herwig, Falk, E-mail: lnsmile@uchicago.edu [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada)

    2014-05-01

    We present barium, carbon, and silicon isotopic compositions of 38 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing barium contamination. Strong depletions in δ({sup 138}Ba/{sup 136}Ba) values are found, down to –400‰, which can only be modeled with a flatter {sup 13}C profile within the {sup 13}C pocket than is normally used. The dependence of δ({sup 138}Ba/{sup 136}Ba) predictions on the distribution of {sup 13}C within the pocket in asymptotic giant branch (AGB) models allows us to probe the {sup 13}C profile within the {sup 13}C pocket and the pocket mass in AGB stars. In addition, we provide constraints on the {sup 22}Ne(α, n){sup 25}Mg rate in the stellar temperature regime relevant to AGB stars, based on δ({sup 134}Ba/{sup 136}Ba) values of mainstream grains. We found two nominally mainstream grains with strongly negative δ({sup 134}Ba/{sup 136}Ba) values that cannot be explained by any of the current AGB model calculations. Instead, such negative values are consistent with the intermediate neutron capture process (i process), which is activated by the very late thermal pulse during the post-AGB phase and characterized by a neutron density much higher than the s process. These two grains may have condensed around post-AGB stars. Finally, we report abundances of two p-process isotopes, {sup 130}Ba and {sup 132}Ba, in single SiC grains. These isotopes are destroyed in the s process in AGB stars. By comparing their abundances with respect to that of {sup 135}Ba, we conclude that there is no measurable decay of {sup 135}Cs (t {sub 1/2} = 2.3 Ma) to {sup 135}Ba in individual SiC grains, indicating condensation of barium, but not cesium into SiC grains before {sup 135}Cs decayed.

  16. Spitzer SAGE-Spec: Near Infrared Spectroscopy, Dust Shells, and Cool Envelopes in Extreme Large Magellanic Cloud Asymptotic Giant Branch Stars

    Science.gov (United States)

    Blum, R. D.; Srinivasan, S.; Kemper, F.; Ling, B.; Volk, K.

    2014-11-01

    K-band spectra are presented for a sample of 39 Spitzer Infrared Spectrograph (IRS) SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near-infrared—Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near-infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars was chosen from the luminous and red extreme ``tip" of the color-magnitude diagram. These objects have properties consistent with dusty envelopes but also cool, carbon-rich ``stellar" cores. Modest amounts of dust mass loss combine with the stellar spectral energy distribution to make these objects appear extreme in their near-infrared and mid-infrared colors. One object in our sample, HV 915, a known post-asymptotic giant branch star of the RV Tau type, exhibits CO 2.3 μm band head emission consistent with previous work that demonstrates that the object has a circumstellar disk. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  17. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars V: Constraining the Mass Loss and Lifetimes of Intermediate Mass, Low Metallicity AGB Stars

    CERN Document Server

    Rosenfield, Philip; Girardi, Léo; Dalcanton, Julianne J; Bressan, Alessandro; Williams, Benjamin F; Dolphin, Andrew

    2016-01-01

    Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) stars are relatively short lived (less than a few Myr), yet their cool effective temperatures, high luminosities, efficient mass-loss and dust production can dramatically effect the chemical enrichment histories and the spectral energy distributions of their host galaxies. The ability to accurately model TP-AGB stars is critical to the interpretation of the integrated light of distant galaxies, especially in redder wavelengths. We continue previous efforts to constrain the evolution and lifetimes of TP-AGB stars by modeling their underlying stellar populations. Using Hubble Space Telescope (HST) optical and near-infrared photometry taken of 12 fields of 10 nearby galaxies imaged via the ACS Nearby Galaxy Survey Treasury and the near-infrared HST/SNAP follow-up campaign, we compare the model and observed TP-AGB luminosity functions as well as the number ratio of TP-AGB to red giant branch stars. We confirm the best-fitting mass-loss prescription, introduced by...

  18. Spitzer SAGE-Spec: Near infrared spectroscopy, dust shells, and cool envelopes in extreme Large Magellanic Cloud asymptotic giant branch stars

    Energy Technology Data Exchange (ETDEWEB)

    Blum, R. D. [NOAO, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Srinivasan, S.; Kemper, F.; Ling, B. [Academia Sinica, Institute of Astronomy and Astrophysics, 11F of Astronomy-Mathematics Building, NTU/AS, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Volk, K. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-11-01

    K-band spectra are presented for a sample of 39 Spitzer Infrared Spectrograph (IRS) SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near-infrared—Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near-infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars was chosen from the luminous and red extreme ''tip'' of the color-magnitude diagram. These objects have properties consistent with dusty envelopes but also cool, carbon-rich ''stellar'' cores. Modest amounts of dust mass loss combine with the stellar spectral energy distribution to make these objects appear extreme in their near-infrared and mid-infrared colors. One object in our sample, HV 915, a known post-asymptotic giant branch star of the RV Tau type, exhibits CO 2.3 μm band head emission consistent with previous work that demonstrates that the object has a circumstellar disk.

  19. New models for the evolution of post-asymptotic giant branch stars and central stars of planetary nebulae

    Science.gov (United States)

    Miller Bertolami, Marcelo Miguel

    2016-04-01

    Context. The post-asymptotic giant branch (AGB) phase is arguably one of the least understood phases of the evolution of low- and intermediate- mass stars. The two grids of models presently available are based on outdated micro- and macrophysics and do not agree with each other. Studies of the central stars of planetary nebulae (CSPNe) and post-AGB stars in different stellar populations point to significant discrepancies with the theoretical predictions of post-AGB models. Aims: We study the timescales of post-AGB and CSPNe in the context of our present understanding of the micro- and macrophysics of stars. We want to assess whether new post-AGB models, based on the latter improvements in TP-AGB modeling, can help us to understand the discrepancies between observation and theory and within theory itself. In addition, we aim to understand the impact of the previous AGB evolution for post-AGB phases. Methods: We computed a grid of post-AGB full evolutionary sequences that include all previous evolutionary stages from the zero age main sequence to the white dwarf phase. We computed models for initial masses between 0.8 and 4 M⊙ and for a wide range of initial metallicities (Z0 = 0.02, 0.01, 0.001, 0.0001). This allowed us to provide post-AGB timescales and properties for H-burning post-AGB objects with masses in the relevant range for the formation of planetary nebulae (~0.5-0.8 M⊙). We included an updated treatment of the constitutive microphysics and included an updated description of the mixing processes and winds that play a key role during the thermal pulses (TP) on the AGB phase. Results: We present a new grid of models for post-AGB stars that take into account the improvements in the modeling of AGB stars in recent decades. These new models are particularly suited to be inputs in studies of the formation of planetary nebulae and for the determination of the properties of CSPNe from their observational parameters. We find post-AGB timescales that are at

  20. On the Relation between the Mysterious 21 Micrometer Emission Feature of Post-Asymptotic Giant Branch Stars and Their Mass Loss Rates

    CERN Document Server

    Mishra, Ajay; Jiang, B W

    2016-01-01

    Over two decades ago, a prominent, mysterious emission band peaking at ~20.1 micrometer was serendipitously detected in four preplanetary nebulae (PPNe; also known as "protoplanetary nebulae"). So far, this spectral feature, designated as the "21 micrometer" feature, has been seen in 18 carbon-rich PPNe. The nature of the carriers of this feature remains unknown although many candidate materials have been proposed. The 21 micrometer sources also exhibit an equally mysterious, unidentified emission feature peaking at 30 micrometer. While the 21 micrometer feature is exclusively seen in PPNe, a short-lived evolutionary stage between the end of the asymptotic giant branch (AGB) and planetary nebula (PN) phases, the 30 micrometer feature is commonly observed in all stages of stellar evolution from the AGB through PPN to PNe phases. We derive the stellar mass loss rates (M_{loss}) of these 21 micrometer sources from their dust infrared (IR) emission, using the "2-DUST" radiative transfer code for axisymmetric dust...

  1. Evolution of thermally pulsing asymptotic giant branch stars. IV. Constraining mass loss and lifetimes of low mass, low metallicity AGB stars

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfield, Philip; Dalcanton, Julianne J.; Weisz, Daniel; Williams, Benjamin F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Marigo, Paola [Department of Physics and Astronomy G. Galilei, University of Padova, Vicolo dell' Osservatorio 3, I-35122 Padova (Italy); Girardi, Léo; Gullieuszik, Marco [Osservatorio Astronomico di Padova—INAF, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Bressan, Alessandro [Astrophysics Sector, SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Dolphin, Andrew [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Aringer, Bernhard [Department of Astrophysics, University of Vienna, Turkenschanzstraße 17, A-1180 Wien (Austria)

    2014-07-20

    The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] ≲ –0.86) galaxies taken from the ACS Nearby Galaxy Survey Treasury sample, using Hubble Space Telescope (HST) photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and red giant branch (RGB) stars, N{sub TP-AGB}/N{sub RGB}, to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust mass loss is important, since models that neglect pre-dust mass loss fail to explain the observed N{sub TP-AGB}/N{sub RGB} ratio or the luminosity functions. In contrast, models with more efficient pre-dust mass loss produce results consistent with observations. We find that for [Fe/H] ≲ –0.86, lower mass TP-AGB stars (M ≲ 1 M{sub ☉}) must have lifetimes of ∼0.5 Myr and higher masses (M ≲ 3 M{sub ☉}) must have lifetimes ≲ 1.2 Myr. In addition, assuming our best-fitting mass-loss prescription, we show that the third dredge-up has no significant effect on TP-AGB lifetimes in this mass and metallicity range.

  2. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars. V. Constraining the Mass Loss and Lifetimes of Intermediate-mass, Low-metallicity AGB Stars

    Science.gov (United States)

    Rosenfield, Philip; Marigo, Paola; Girardi, Léo; Dalcanton, Julianne J.; Bressan, Alessandro; Williams, Benjamin F.; Dolphin, Andrew

    2016-05-01

    Thermally pulsing asymptotic giant branch (TP-AGB) stars are relatively short lived (less than a few Myr), yet their cool effective temperatures, high luminosities, efficient mass loss, and dust production can dramatically affect the chemical enrichment histories and the spectral energy distributions of their host galaxies. The ability to accurately model TP-AGB stars is critical to the interpretation of the integrated light of distant galaxies, especially in redder wavelengths. We continue previous efforts to constrain the evolution and lifetimes of TP-AGB stars by modeling their underlying stellar populations. Using Hubble Space Telescope (HST) optical and near-infrared photometry taken of 12 fields of 10 nearby galaxies imaged via the Advanced Camera for Surveys Nearby Galaxy Survey Treasury and the near-infrared HST/SNAP follow-up campaign, we compare the model and observed TP-AGB luminosity functions as well as the ratio of TP-AGB to red giant branch stars. We confirm the best-fitting mass-loss prescription, introduced by Rosenfield et al., in which two different wind regimes are active during the TP-AGB, significantly improves models of many galaxies that show evidence of recent star formation. This study extends previous efforts to constrain TP-AGB lifetimes to metallicities ranging -1.59 ≲ {{[Fe/H]}} ≲ -0.56 and initial TP-AGB masses up to ˜4 M ⊙, which include TP-AGB stars that undergo hot-bottom burning. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  3. The Stellar Spectral Features of Nearby Galaxies in the Near-Infrared: Tracers of Thermally-Pulsing Asymptotic Giant Branch Stars?

    CERN Document Server

    Riffel, Rogério; Martins, Lucimara P; Rodíguez-Ardila, Alberto; Ho, Luis C; Riffel, Rogemar A; Lira, Paulina; Martin, Omaira Gonzalez; Ruschel-Dutra, Daniel; Alonso-Herrero, Almudena; Flohic, Helene; McDermid, Richard M; Almeida, Cristina Ramos; Thanjavur, Karun; Winge, Claudia

    2015-01-01

    We analyze the stellar absorption features in high signal-to-noise ratio near-infrared (NIR) spectra of the nuclear region of 12 nearby galaxies, mostly spirals. The features detected in some or all of the galaxies in this sample are the TiO (0.843 $\\mu$m\\ and 0.886 $\\mu$m), VO (1.048 $\\mu$m), CN (1.1 $\\mu$m\\ and 1.4 $\\mu$m), H$\\rm _2$O (1.4 $\\mu$m\\ and 1.9 $\\mu$m) and CO (1.6 $\\mu$m\\ and 2.3 $\\mu$m) bands. The C$\\rm _2$ (1.17 $\\mu$m\\ and 1.76 $\\mu$m) bands are generally weak or absent, although C$\\rm _2$ (1.76 $\\mu$m) may be weakly present in the mean galaxy spectrum. A deep feature near 0.93 $\\mu$m, likely caused by CN, TiO and/or ZrO, is also detected in all objects. Fitting a combination of stellar spectra to the mean spectrum shows that the absorption features are produced by evolved stars: cool giants and supergiant stars in the early- or thermally-pulsing asymptotic giant branch (E-AGB or TP-AGB) phases. The high luminosity of TP-AGB stars, and the appearance of VO and ZrO features in the data, suggest...

  4. The impact of updated Zr neutron-capture cross sections and new asymptotic giant branch models on our understanding of the s process and the origin of stardust

    CERN Document Server

    Lugaro, Maria; Karakas, Amanda I; Milazzo, Paolo M; Kaeppeler, Franz; Davis, Andrew M; Savina, Michael R

    2013-01-01

    We present model predictions for the Zr isotopic ratios produced by slow neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25 to 4 Msun and metallicities Z=0.01 to 0.03, and compare them to data from single meteoritic stardust silicon carbide (SiC) and high-density graphite grains that condensed in the outflows of these stars. We compare predictions produced using the Zr neutron-capture cross section from Bao et al. (2000) and from n_TOF experiments at CERN, and present a new evaluation for the neutron-capture cross section of the unstable isotope 95Zr, the branching point leading to the production of 96Zr. The new cross sections generally presents an improved match with the observational data, except for the 92Zr/94Zr ratios, which are on average still substantially higher than predicted. The 96Zr/94Zr ratios can be explained using our range of initial stellar masses, with the most 96Zr-depleted grains originating from AGB stars of masses 1.8 - 3 Msun, and the others from either lowe...

  5. The identification of extreme asymptotic giant branch stars and red supergiants in M33 with 24 μm variability

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, Edward J.; Clayton, Geoffrey C.; Johnson, Christopher B. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Srinivasan, Sundar [Academica Sinica, Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei 10617, Taiwan, R. O. C. (China); Engelbracht, Charles W., E-mail: emonti2@lsu.edu [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2015-02-01

    We present the first detection of 24 μm variability in 24 sources in the Local Group galaxy M33. These results are based on 4 epochs of Multiband Imaging Photometer for Spitzer observations, which are irregularly spaced over ∼750 days. We find that these sources are constrained exclusively to the Holmberg radius of the galaxy, which increases their chances of being members of M33. We have constructed spectral energy distributions (SEDs) ranging from the optical to the submillimeter to investigate the nature of these objects. We find that 23 of our objects are most likely heavily self-obscured, evolved stars, while the remaining source is the Giant H ii region, NGC 604. We believe that the observed variability is the intrinsic variability of the central star reprocessed through their circumstellar dust shells. Radiative transfer modeling was carried out to determine their likely chemical composition, luminosity, and dust production rate (DPR). As a sample, our modeling has determined an average luminosity of (3.8±0.9)×10{sup 4} L{sub ⊙} and a total DPR of (2.3±0.1)×10{sup −5} M{sub ⊙} yr{sup −1}. Most of the sources, given the high DPRs and short wavelength obscuration, are likely extreme asymptotic giant branch (XAGB) stars. Five of the sources are found to have luminosities above the classical AGB limit (M{sub bol} <−7.1 mag, L > 54,000 L{sub ⊙}), which classifies them as probable red supergiants (RSGs). Almost all of the sources are classified as oxygen-rich. As also seen in the LMC, a significant fraction of the dust in M33 is produced by a handful of XAGB and RSG stars.

  6. Seismic evidence for a rapidly rotating core in a lower-giant-branch star observed with Kepler

    CERN Document Server

    Deheuvels, S; Chaplin, W J; Basu, S; Antia, H M; Appourchaux, T; Benomar, O; Davies, G R; Elsworth, Y; Gizon, L; Goupil, M J; Reese, D R; Regulo, C; Schou, J; Stahn, T; Casagrande, L; Christensen-Dalsgaard, J; Fischer, D; Hekker, S; Kjeldsen, H; Mathur, S; Mosser, B; Pinsonneault, M; Valenti, J; Christiansen, J L; Kinemuchi, K; Mullally, F

    2012-01-01

    Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on the internal rotation of stars, which until very recently were restricted to the Sun. In this paper, we report the detection of mixed modes - i.e. modes that behave both as g modes in the core and as p modes in the envelope - in the spectrum of the early red giant KIC7341231, which was observed during one year with the Kepler spacecraft. By performing an analysis of the oscillation spectrum of the star, we show that its non-radial modes are clearly split by stellar rotation and we are able to determine precisely the rotational splittings of 18 modes. We then find a stellar model that reproduces very well the observed atmospheric and seismic properties of the star. ...

  7. The Identification of Extreme Asymptotic Giant Branch Stars and Red Supergiants in M33 by 24 {\\mu}m Variability

    CERN Document Server

    Montiel, Edward J; Clayton, Geoffrey C; Engelbracht, Charles W; Johnson, Christopher B

    2014-01-01

    We present the first detection of 24 {\\mu}m variability in 24 sources in the Local Group galaxy M33. These results are based on 4 epochs of MIPS observations, which are irregularly spaced over ~750 days. We find that these sources are constrained exclusively to the Holmberg radius of the galaxy, which increases their chances of being members of M33. We have constructed spectral energy distributions (SEDs) ranging from the optical to the sub-mm to investigate the nature of these objects. We find that 23 of our objects are most likely heavily self-obscured, evolved stars; while the remaining source is the Giant HII region, NGC 604. We believe that the observed variability is the intrinsic variability of the central star reprocessed through their circumstellar dust shells. Radiative transfer modeling was carried out to determine their likely chemical composition, luminosity, and dust production rate (DPR). As a sample, our modeling has determined an average luminosity of (3.8 $\\pm$ 0.9) x 10$^4$ L$_\\odot$ and a ...

  8. Three discrete groups with homogeneous chemistry along the red giant branch in the globular cluster NGC 2808

    CERN Document Server

    Carretta, Eugenio

    2014-01-01

    We present the homogeneous reanalysis of Mg and Al abundances from high resolution UVES/FLAMES spectra for 31 red giants in the globular cluster NGC 2808. We found a well defined Mg-Al anticorrelation reaching a regime of subsolar Mg abundance ratios, with a spread of about 1.4 dex in [Al/Fe]. The main result from the improved statistics of our sample is that the distribution of stars is not continuous along the anticorrelation as they are neatly clustered into three distinct clumps each with different chemical composition. One group (P) shows the primordial composition of field stars of similar metallicity, and the other two (I and E) have increasing abundances of Al and decreasing abundances of Mg. The fraction of stars we found in the three components (P: 68%, I: 19%, E: 13%) is in excellent agreement with the number ratios computed for the three distinct main sequences in NGC 2808: for the first time there is a clear correspondence between discrete photometric sequences of dwarfs and distinct groups of gi...

  9. The impact of updated Zr neutron-capture cross sections and new asymptotic giant branch models on our understanding of the S process and the origin of stardust

    Energy Technology Data Exchange (ETDEWEB)

    Lugaro, Maria [Monash Centre for Astrophysics (MoCA), Monash University, Clayton, VIC 3800 (Australia); Tagliente, Giuseppe [Istituto Nazionale di Fisica Nucleare (INFN), Bari (Italy); Karakas, Amanda I. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Milazzo, Paolo M. [Istituto Nazionale di Fisica Nucleare (INFN), Trieste (Italy); Käppeler, Franz [Karlsruhe Institute of Technology, Campus North, D-76021 Karlsruhe (Germany); Davis, Andrew M. [The Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637 (United States); Savina, Michael R., E-mail: maria.lugaro@monash.edu, E-mail: giuseppe.tagliente@ba.infn.it, E-mail: amanda.karakas@anu.edu.au, E-mail: paolo.milazzo@ts.infn.it, E-mail: franz.kaeppeler@kit.edu, E-mail: a-davis@uchicago.edu, E-mail: msavina@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2014-01-01

    We present model predictions for the Zr isotopic ratios produced by slow neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25-4 M {sub ☉} and metallicities Z = 0.01-0.03, and compare them to data from single meteoritic stardust silicon carbide (SiC) and high-density graphite grains that condensed in the outflows of these stars. We compare predictions produced using the Zr neutron-capture cross sections from Bao et al. and from n{sub T}OF experiments at CERN, and present a new evaluation for the neutron-capture cross section of the unstable isotope {sup 95}Zr, the branching point leading to the production of {sup 96}Zr. The new cross sections generally present an improved match with the observational data, except for the {sup 92}Zr/{sup 94}Zr ratios, which are on average still substantially higher than predicted. The {sup 96}Zr/{sup 94}Zr ratios can be explained using our range of initial stellar masses, with the most {sup 96}Zr-depleted grains originating from AGB stars of masses 1.8-3 M {sub ☉} and the others from either lower or higher masses. The {sup 90,} {sup 91}Zr/{sup 94}Zr variations measured in the grains are well reproduced by the range of stellar metallicities considered here, which is the same needed to cover the Si composition of the grains produced by the chemical evolution of the Galaxy. The {sup 92}Zr/{sup 94}Zr versus {sup 29}Si/{sup 28}Si positive correlation observed in the available data suggests that stellar metallicity rather than rotation plays the major role in covering the {sup 90,} {sup 91,} {sup 92}Zr/{sup 94}Zr spread.

  10. Habitability of Super-Earth Planets around Main-Sequence Stars including Red Giant Branch Evolution: Models based on the Integrated System Approach

    CERN Document Server

    Cuntz, M; Schroeder, K -P; Bounama, C; Franck, S

    2011-01-01

    In a previous study published in Astrobiology, we focused on the evolution of habitability of a 10 M_E super-Earth planet orbiting a star akin to the Sun. This study was based on a concept of planetary habitability in accordance to the integrated system approach that describes the photosynthetic biomass production taking into account a variety of climatological, biogeochemical, and geodynamical processes. In the present study, we pursue a significant augmentation of our previous work by considering stars with zero-age main sequence masses between 0.5 and 2.0 M_sun with special emphasis on models of 0.8, 0.9, 1.2 and 1.5 M_sun. Our models of habitability consider again geodynamical processes during the main-sequence stage of these stars as well as during their red giant branch evolution. Pertaining to the different types of stars, we identify so-called photosynthesis-sustaining habitable zones (pHZ) determined by the limits of biological productivity on the planetary surface. We obtain various sets of solution...

  11. Identification of a Class of Low-Mass Asymptotic Giant Branch Stars Struggling to Become Carbon Stars in the Magellanic Clouds

    CERN Document Server

    Boyer, Martha L; Srinivasan, Sundar; Zijlstra, Albert; van Loon, Jacco Th; Olsen, Knut A G; Sonneborn, George

    2015-01-01

    We have identified a new class of Asymptotic Giant Branch (AGB) stars in the Small and Large Magellanic Clouds (SMC/LMC) using optical to infrared photometry, light curves, and optical spectroscopy. The strong dust production and long-period pulsations of these stars indicate that they are at the very end of their AGB evolution. Period-mass-radius relations for the fundamental-mode pulsators give median current stellar masses of 1.14 M_sun in the LMC and 0.94 M_sun in the SMC (with dispersions of 0.21 and 0.18 M_sun, respectively), and models suggest initial masses of <1.5 M_sun and <1.25 M_sun, respectively. This new class of stars includes both O-rich and C-rich chemistries, placing the limit where dredge-up allows carbon star production below these masses. A high fraction of the brightest among them should show S star characteristics indicative of atmospheric C/O ~ 1, and many will form O-rich dust prior to their C-rich phase. These stars can be separated from their less-evolved counterparts by their...

  12. The Carina Project VII: Towards the breaking of the age-metallicity degeneracy of red giant branch stars using the c_UBI index

    CERN Document Server

    Monelli, M; Fabrizio, M; Bono, G; Stetson, P B; Walker, A R; Cassisi, S; Gallart, C; Nonino, M; Aparicio, A; Buonanno, R; Dall'Ora, M; Ferraro, I; Iannicola, G; Pulone, L; Thévenin, F

    2014-01-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper colour combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, \\sim 12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c_UBI=(U-B)-(B-I) pseudo-colour allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have more negative c_UBI pseudo-colour than intermediate-age ones. We correlate the pseudo-colour of RGB stars with their chemical properties, finding a significant trend between the iron content and the c_UBI. Stars belonging to the old population are systematically more metal poor ([Fe/H]=-2.32\\pm0.08 dex) than the intermediate-age ones ([Fe/H]=-1.82\\pm0.03 dex). This gives solid evidence on the chemical evolution history of this g...

  13. The Tip of the Red Giant Branch Distances to Type Ia Supernova Host Galaxies. IV. Color Dependence and Zero-point Calibration

    Science.gov (United States)

    Jang, In Sung; Lee, Myung Gyoon

    2017-01-01

    We present a revised Tip of the Red Giant Branch (TRGB) calibration, accurate to 2.7% of distance. A modified TRGB magnitude corrected for its color dependence, the QT magnitude, is introduced for better measurement of the TRGB. We determine the color–magnitude relation of the TRGB from photometry of deep images of HST/ACS fields around eight nearby galaxies. The zero-point of the TRGB at the fiducial metallicity ([Fe/H] = ‑1.6 ({(V-I)}0,{TRGB}=1.5)) is obtained from photometry of two distance anchors, NGC 4258 (M106) and the Large Magellanic Cloud (LMC), to which precise geometric distances are known: MQT,TRGB = ‑4.023 ± 0.073 mag from NGC 4258 and MQT,TRGB = ‑4.004 ± 0.096 mag from the LMC. A weighted mean of the two zero-points is MQT,TRGB = ‑4.016 ± 0.058 mag. Quoted uncertainty is ∼2× smaller than those of previous calibrations. We compare the empirical TRGB calibration derived in this study with theoretical stellar models, finding that there are significant discrepancies, especially for red color ({({{F}}606{{W}}-{{F}}814{{W}})}0≳ 2.5). We provide the revised TRGB calibration in several magnitude systems for future studies.

  14. Formation of SiC Grains in Pulsation-Enhanced Dust-Driven Wind Around Carbon Rich Asymptotic Giant Branch Stars

    CERN Document Server

    Yasuda, Yuki

    2011-01-01

    We investigate the formation of silicon carbide (SiC) grains in the framework of dust-driven wind around pulsating carbon-rich Asymptotic Giant Branch (C-rich AGB) stars in order to reveal not only the amount but also the size distribution. Two cases are considered for the nucleation process; one is the LTE case where the vibration temperature of SiC clusters $T_{\\rm v}$ is equal to the gas temperature as usual, and another is the non-LTE case in which $T_{\\rm v}$ is assumed to be the same as the temperature of small SiC grains. The results of hydrodynamical calculations for a model with stellar parameters of mass $M_{\\ast}$=1.0 $M_{\\odot}$, luminosity $L_{\\ast}$=10$^{4}$ $L_{\\odot}$, effective temperature $T_{\\rm eff}$=2600 K, C/O ratio=1.4, and pulsation period $P$=650 days show the followings: In the LTE case, SiC grains condense in accelerated outflowing gas after the formation of carbon grains and the resulting averaged mass ratio of SiC to carbon grains of $\\sim$ 10$^{-8}$ is too small to reproduce the ...

  15. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars IV. Constraining Mass-Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars

    CERN Document Server

    Rosenfield, Philip; Girardi, Leo; Dalcanton, Julianne J; Bressan, Alessandro; Gullieuszik, Marco; Weisz, Daniel; Williams, Benjamin F; Dolphin, Andrew; Aringer, Bernhard

    2014-01-01

    The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] $\\lesssim -0.86$) galaxies taken from the ANGST sample, using HST photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and RGB stars, to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories (SFH) derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass-loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust mass-loss is important, since models that neglect pre-dust mass-loss fail to explain the observed TP-AGB/RGB ratio or the luminosity functions. In ...

  16. The mass-loss return from evolved stars to the Large Magellanic Cloud III. Dust properties for carbon-rich asymptotic giant branch stars

    CERN Document Server

    Srinivasan, Sundar; Matsuura, M; Meixner, M; Kemper, F; Tielens, A G G M; Volk, K; Speck, A K; Woods, Paul M; Gordon, K; Marengo, M; Sloan, G C

    2010-01-01

    We present a 2Dust model for the dust shell around a LMC long-period variable (LPV) previously studied as part of the OGLE survey. OGLE LMC LPV 28579 (SAGE J051306.40-690946.3) is a carbon-rich asymptotic giant branch (AGB) star for which we have photometry and spectra from the Spitzer SAGE and SAGE-Spec programs along with UBVIJHK_s photometry. By modeling this source, we obtain a baseline set of dust properties to be used in the construction of a grid of models for carbon stars. We reproduce its spectral energy distribution using a mixture of AmC and SiC (15% by mass). The grain sizes are distributed according to the KMH model. The best-fit model has an optical depth of 0.28 for the shell at the peak of the SiC feature, with R_in~1430 R_sun or 4.4 R_star. The temperature at this inner radius is 1310 K. Assuming an expansion velocity of 10 km s^-1, we obtain a dust mass-loss rate of 2.5x10^-9 M_sun yr-1. We calculate a 15% variation in this rate by testing the fit sensitivity against variation in input param...

  17. The Mass-Loss Return from Evolved Stars to the Large Magellanic Cloud II: Dust Properties for Oxygen-Rich Asymptotic Giant Branch Stars

    CERN Document Server

    Sargent, Benjamin A; Meixner, M; Kemper, F; Tielens, A G G M; Speck, A K; Matsuura, M; Bernard, J -Ph; Hony, S; Gordon, Karl D; Indebetouw, R; Marengo, M; Sloan, G C; Woods, Paul M

    2014-01-01

    We model multi-wavelength broadband UBVIJHKs and Spitzer IRAC and MIPS photometry and IRS spectra from the SAGE and SAGE-Spec observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer models of dust shells around stars. We chose a star from each of the bright and faint O-rich AGB populations found by earlier studies of the SAGE sample in order to derive a baseline set of dust properties to be used in the construction of an extensive grid of radiative transfer models of the O-rich AGB stars found in the SAGE surveys. From the bright O-rich AGB population we chose HV 5715, and from the faint O-rich AGB population we chose SSTISAGE1C J052206.92-715017.6 (SSTSAGE052206). We found the complex indices of refraction of oxygen-deficient silicates from Ossenkopf et al (1992) and a "KMH"-like grain size distribution with gamma of -3.5, a_min of 0.01 microns, and a_0 of 0.1 microns to be reasonable dust properties for these models. There...

  18. Super-Nyquist asteroseismology of solar-like oscillators with Kepler and K2 - expanding the asteroseismic cohort at the base of the red-giant branch

    CERN Document Server

    Chaplin, W J; Davies, G R; Campante, T L; Handberg, R; Miglio, A; Basu, S

    2014-01-01

    We consider the prospects for detecting solar-like oscillations in the "super-Nyquist" regime of long-cadence (LC) Kepler photometry, i.e., above the associated Nyquist frequency of approximately 283 {\\mu}Hz. Targets of interest are cool, evolved subgiants and stars lying at the base of the red-giant branch. These stars would ordinarily be studied using the short-cadence (SC) data, since the associated SC Nyquist frequency lies well above the frequencies of the detectable oscillations. However, the number of available SC target slots is quite limited. This imposes a severe restriction on the size of the ensemble available for SC asteroseismic study.We find that archival Kepler LC data from the nominal Mission may be utilized for asteroseismic studies of targets whose dominant oscillation frequencies lie as high as approximately 500 {\\mu}Hz, i.e., about 1.75- times the LC Nyquist frequency. The frequency detection threshold for the shorter-duration science campaigns of the re-purposed Kepler Mission, K2, is lo...

  19. A superconducting tunnel junction receiver for submillimeter astronomy, and analysis of observations of post-AGB star molecular envelopes. [AGB (asymptotic giant branch)

    Energy Technology Data Exchange (ETDEWEB)

    Jaminet, P.A.

    1992-01-01

    A heterodyne receiver designed for astronomical use between 450 and 520 GHz has been constructed. Very low capacitance (C [approximately] 5-10 fF) Superconductor-Insulator-Superconductor (SIS) junctions have been fabricated as the detectors; these junctions lie on the edges of niobium thin films and form Nb-Al-Al[sub 2]O[sub 3]-Al-Nb sandwiches. The double sideband (DSB) receiver noise temperature is between 400 K and 800 K throughout the 70 GHz band. In addition, detailed modelling and analysis of astronomical observations of two post-AGB (Asymptotic Giant Branch) stars was performed. The observations were made with an SIS receiver designed for 345 GHz. CO observations and modelling of the young planetary nebula NGC 7027 provided the best determination yet of its AGB mass loss rate, the first direct evidence for bipolarity in its AGB mass loss, evidence for close hydrodynamic coupling between the planetary nebula and the relic AGB wind, and evidence for evolution in the metallicity of the stellar wind. Observations of the proto-planetary nebula CRL 2688 found evidence for spatially extended fast wind emission with a non-bipolar morphology, and evidence for evolution is elemental abundances in the stellar wind.

  20. Connecting the evolution of thermally pulsing asymptotic giant branch stars to the chemistry in their circumstellar envelopes -- I. The case of hydrogen cyanide

    CERN Document Server

    Marigo, Paola; Nanni, Ambra; Bressan, Alessandro; Girardi, Leo

    2015-01-01

    We investigate the formation of hydrogen cyanide (HCN) in the inner circumstellar envelopes of thermally pulsing asymptotic giant branch (TP-AGB) stars. A dynamic model for periodically shocked atmospheres, which includes an extended chemo-kinetic network, is for the first time coupled to detailed evolutionary tracks for the TP-AGB phase computed with the COLIBRI code. We carried out a calibration of the main shock parameters (the shock formation radius and the effective adiabatic index) using the circumstellar HCN abundances recently measured for a populous sample of pulsating TP-AGB stars. Our models recover the range of the observed HCN concentrations as a function of the mass-loss rates, and successfully reproduce the systematic increase of HCN moving along the M-S-C chemical sequence of TP-AGB stars, that traces the increase of the surface C/O ratio. The chemical calibration brings along two important implications: i) the first shock should emerge very close to the photosphere, and ii) shocks are expecte...

  1. On the necessity of composition-dependent low-temperature opacity in models of metal-poor asymptotic giant branch stars

    Energy Technology Data Exchange (ETDEWEB)

    Constantino, Thomas; Campbell, Simon; Lattanzio, John [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Victoria 3800 (Australia); Gil-Pons, Pilar, E-mail: thomas.constantino@monash.edu [Department of Applied Physics, Polytechnic University of Catalonia, 08860 Barcelona (Spain)

    2014-03-20

    The vital importance of composition-dependent low-temperature opacity in low-mass (M ≤ 3 M {sub ☉}) asymptotic giant branch (AGB) stellar models of metallicity Z ≥ 0.001 has recently been demonstrated. Its significance to more metal-poor, intermediate-mass (M ≥ 2.5 M {sub ☉}) models has yet to be investigated. We show that its inclusion in lower-metallicity models ([Fe/H] ≤–2) is essential and that there exists no threshold metallicity below which composition-dependent molecular opacity may be neglected. We find it to be crucial in all intermediate-mass models investigated ([Fe/H] ≤–2 and 2.5 ≤ M/M {sub ☉} ≤ 5), because of the evolution of the surface chemistry, including the orders of magnitude increase in the abundance of molecule-forming species. Its effect on these models mirrors that previously reported for higher-metallicity models—increase in radius, decrease in T {sub eff}, faster mass loss, shorter thermally pulsing AGB lifetime, reduced enrichment in third dredge-up products (by a factor of 3-10), and an increase in the mass limit for hot bottom burning. We show that the evolution of low-metallicity models with composition-dependent low-temperature opacity is relatively independent of initial metal abundance because its contribution to the opacity is far outweighed by changes resulting from dredge-up. Our results imply a significant reduction in the expected number of nitrogen-enhanced metal-poor stars, which may help explain their observed paucity. We note that these findings are partially a product of the macrophysics adopted in our models, in particular, the Vassiliadis and Wood mass loss rate which is strongly dependent on radius.

  2. The Carina project. VII. Toward the breaking of the age-metallicity degeneracy of red giant branch stars using the C {sub U,} {sub B,} {sub I} index

    Energy Technology Data Exchange (ETDEWEB)

    Monelli, M.; Milone, A. P.; Gallart, C.; Aparicio, A. [Instituto de Astrofísica de Canarias, Calle Via Lactea s/n, E-38205 La Laguna, Tenerife (Spain); Fabrizio, M.; Cassisi, S.; Buonanno, R. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico Collurania, Via M. Maggini, I-64100 Teramo (Italy); Bono, G. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Stetson, P. B. [Dominion Astrophysical Observatory, NRC-Herzberg, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Walker, A. R. [Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile); Nonino, M. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-40131 Trieste (Italy); Dall' Ora, M. [INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Ferraro, I.; Iannicola, G.; Pulone, L. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, I-00044 Rome (Italy); Thévenin, F., E-mail: monelli@iac.es [Université de Nice Sophia-antipolis, CNRS, Observatoire de la Côte d' Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice (France)

    2014-12-01

    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper color combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, ∼12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c {sub U,} {sub B,} {sub I} = (U – B) – (B – I) pseudo-color allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have a more negative c {sub U,} {sub B,} {sub I} pseudo-color than intermediate-age ones. We correlate the pseudo-color of RGB stars with their chemical properties, finding a significant trend between the iron content and the c {sub U,} {sub B,} {sub I}. Stars belonging to the old population are systematically more metal-poor ([Fe/H] =–2.32 ± 0.08 dex) than the intermediate-age ones ([Fe/H] =–1.82 ± 0.03 dex). This gives solid evidence of the chemical evolution history of this galaxy, and we have a new diagnostic that can allow us to break the age-metallicity degeneracy of H-burning advanced evolutionary phases. We compared the distribution of stars in the c {sub U,} {sub B,} {sub I} plane with theoretical isochrones, finding that no satisfactory agreement can be reached with models developed in a theoretical framework based on standard heavy element distributions. Finally, we discuss possible systematic differences when compared with multiple populations in GCs.

  3. DRAMATIC INFRARED VARIABILITY OF WISE J1810-3305: CATCHING EARLY-TIME DUST EJECTION DURING THE THERMAL PULSE OF AN ASYMPTOTIC GIANT BRANCH STAR?

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, Poshak; Yamamura, Issei; Takita, Satoshi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2012-05-20

    We present the discovery of a source with broadband infrared photometric characteristics similar to Sakurai's object. WISE J180956.27-330500.2 (hereafter J1810-3305) shows very red WISE colors, but a very blue 2MASS [K] versus WISE [W1 (3.4 {mu}m)] color. It was not visible during the IRAS era, but now has a 12 {mu}m flux well above the IRAS point-source catalog detection limit. There are also indications of variability in historical optical photographic plates as well as in multi-epoch AKARI mid-infrared measurements. The broadband infrared spectral energy distribution (SED) shape, post-IRAS brightening, and multiwavelength variability are all characteristics also shared by Sakurai's object-a post-asymptotic giant branch (post-AGB) star which underwent a late thermal pulse and recently ejected massive envelopes of dust that are currently expanding and cooling. Optical progenitor colors suggest that J1810-3305 may have been of late spectral class. Its dramatic infrared brightening and the detection of a late-type optical counterpart are consistent with a scenario in which we have caught an extremely massive dust ejection event (in 1998 or shortly before) during the thermal pulse of an AGB star, thus providing a unique opportunity to observe stellar evolution in this phase. J1810-3305 is the only source in the entire WISE preliminary data release with similar infrared SED and variability, emphasizing the rarity of such sources. Confirmation of its nature is of great importance.

  4. EUROPIUM s-PROCESS SIGNATURE AT CLOSE-TO-SOLAR METALLICITY IN STARDUST SiC GRAINS FROM ASYMPTOTIC GIANT BRANCH STARS

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Janaina N.; Ireland, Trevor R.; Holden, Peter [Research School of Earth Sciences, Australian National University, Canberra ACT 0200 (Australia); Lugaro, Maria [Monash Centre for Astrophysics, Monash University, Clayton, VIC 3800 (Australia); Gyngard, Frank; Zinner, Ernst [Laboratory for Space Sciences and the Department of Physics, Washington University, One Brookings Drive, St. Louis, MO 63130 (United States); Cristallo, Sergio [Osservatorio Astronomico di Collurania, INAF, via Maggini snc, Teramo I-64100 (Italy); Rauscher, Thomas, E-mail: janaina.avila@anu.edu.au [Centre for Astrophysics Research, School of Physics, Astronomy, and Mathematics, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)

    2013-05-01

    Individual mainstream stardust silicon carbide (SiC) grains and a SiC-enriched bulk sample from the Murchison carbonaceous meteorite have been analyzed by the Sensitive High Resolution Ion Microprobe-Reverse Geometry for Eu isotopes. The mainstream grains are believed to have condensed in the outflows of {approx}1.5-3 M{sub Sun} carbon-rich asymptotic giant branch (AGB) stars with close-to-solar metallicity. The {sup 151}Eu fractions [fr({sup 151}Eu) = {sup 151}Eu/({sup 151}Eu+{sup 153}Eu)] derived from our measurements are compared with previous astronomical observations of carbon-enhanced metal-poor stars enriched in elements made by slow neutron captures (the s-process). Despite the difference in metallicity between the parent stars of the grains and the metal-poor stars, the fr({sup 151}Eu) values derived from our measurements agree well with fr({sup 151}Eu) values derived from astronomical observations. We have also compared the SiC data with theoretical predictions of the evolution of Eu isotopic ratios in the envelope of AGB stars. Because of the low Eu abundances in the SiC grains, the fr({sup 151}Eu) values derived from our measurements show large uncertainties, in most cases being larger than the difference between solar and predicted fr({sup 151}Eu) values. The SiC aggregate yields a fr({sup 151}Eu) value within the range observed in the single grains and provides a more precise result (fr({sup 151}Eu) = 0.54 {+-} 0.03, 95% conf.), but is approximately 12% higher than current s-process predictions. The AGB models can match the SiC data if we use an improved formalism to evaluate the contribution of excited nuclear states in the calculation of the {sup 151}Sm(n, {gamma}) stellar reaction rate.

  5. The Carnegie-Chicago Hubble Program. II. The Distance to IC 1613: The Tip of the Red Giant Branch and RR Lyrae Period-luminosity Relations

    Science.gov (United States)

    Hatt, Dylan; Beaton, Rachael L.; Freedman, Wendy L.; Madore, Barry F.; Jang, In-Sung; Hoyt, Taylor J.; Lee, Myung Gyoon; Monson, Andrew J.; Rich, Jeffrey A.; Scowcroft, Victoria; Seibert, Mark

    2017-08-01

    IC 1613 is an isolated dwarf galaxy within the Local Group. Low foreground and internal extinction, low metallicity, and low crowding make it an invaluable testbed for the calibration of the local distance ladder. We present new, high-fidelity distance estimates to IC 1613 via its Tip of the Red Giant Branch (TRGB) and its RR Lyrae (RRL) variables as part of the Carnegie-Chicago Hubble Program, which seeks an alternate local route to H 0 using Population II stars. We have measured a TRGB magnitude {I}{ACS}{TRGB}=20.35+/- {0.01}{stat}+/- {0.01}{sys} mag using wide-field observations obtained from the IMACS camera on the Magellan-Baade telescope. We have further constructed optical and near-infrared RRL light curves using archival BI- and new H-band observations from the ACS/WFC and WFC3/IR instruments on board the Hubble Space Telescope (HST). In advance of future Gaia data releases, we set provisional values for the TRGB luminosity via the Large Magellanic Cloud and Galactic RRL zero-points via HST parallaxes. We find corresponding true distance moduli {μ }0{TRGB}=24.30+/- {0.03}{stat}+/- {0.05}{sys} {mag} and =24.28+/- {0.04}{stat+{sys}} mag. We compare our results to a body of recent publications on IC 1613 and find no statistically significant difference between the distances derived from Population I and II stars. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs #10505 and #13691. Additional observations are credited to the Observatories of the Carnegie Institution of Washington for the use of Magellan-Baade IMACS. Presented as part of a dissertation to the Department of Astronomy and Astrophysics, The University of Chicago, in partial fulfillment of the requirements for the Ph.D. degree.

  6. Puzzling Origin of CEMP-r/s Stars: An Interpretation of Abundance and Enrichment of s- and r-Process Elements from Asymptotic Giant Branch Supernovae

    Indian Academy of Sciences (India)

    Jiang Zhang; Fang Zhao; Yanping Chen; Wenyuan Cui; Bo Zhang

    2013-12-01

    CEMP-r/s stars at low metallicity are known as double-enhanced stars that show enhancements of both r-process and s-process elements. The chemical abundances of these very metal-poor stars provide us a lot of information for putting new restraints on models of neutron-capture processes. In this article, we put forward an accreted scenario in which the double enrichment of r-process and s-process elements is caused by a former intermediate-mass Asymptotic Giant Branch (AGB) companion in a detached binary system. As the AGB superwind is only present at the ultimate phase of AGB stars, there is thus a lot of potential that the degenerate-core mass of an intermediate-mass AGB star reaches the Chandrasekhar limit before the AGB superwind. In these circumstances, both s-process elements produced in the AGB shell and r-process elements synthesized in the subsequent explosion would be sprayed contemporaneously and accreted by its companion. Despite similarity to physical conditions of a core-collapse supernova, a major focus in this scenario is the degenerate C–O core surrounded by an envelope of a former intermediate-mass AGB donor that may collapse and explode. Due to the existence of an outer envelope, r-process nucleosynthesis is expected to occur. Hypothesizing the material-rich europium (Eu) accreted by the secondary via the wind from the supernova to be in proportion to the geometric fraction of the companion with respect to the exploding donor star, we find that the estimated yield of Eu (as representative of r-process elements) per AGB supernova event is about 1 × 10-9⊙ ∼ 5 × 10-9⊙. Using the yields of Eu, the overabundance of r-process elements in CEMP-r/s stars can be accounted for. The calculated results show that the value of parameter , standing for efficiency of wind pollution from the AGB supernova, will reach about 104, which means that the enhanced factor is much larger than unity due to the impact of gravity of the donor and the result of the

  7. Intermediate-mass Asymptotic Giant Branch Stars and Sources of 26Al, 60Fe, 107Pd, and 182Hf in the Solar System

    Science.gov (United States)

    Wasserburg, G. J.; Karakas, Amanda I.; Lugaro, Maria

    2017-02-01

    We explore the possibility that the short-lived radionuclides {}26{{A}}l, {}60{{F}}e, {}107{{P}}d, and {}182{{H}}f inferred to be present in the proto-solar cloud originated from 3–8 {M}ȯ asymptotic giant branch (AGB) stars. Models of AGB stars with initial mass above 5 {M}ȯ are prolific producers of {}26{{A}}l owing to hot bottom burning (HBB). In contrast, {}60{{F}}e, {}107{{P}}d, and {}182{{H}}f are produced by neutron captures: {}107{{P}}d and {}182{{H}}f in models ≲ 5 {M}ȯ , and {}60{{F}}e in models with higher mass. We mix stellar yields from solar-metallicity AGB models into a cloud of solar mass and composition to investigate whether it is possible to explain the abundances of the four radioactive nuclides at the Sun’s birth using one single value of the mixing ratio between the AGB yields and the initial cloud material. We find that AGB stars that experience efficient HBB (≥slant 6 {M}ȯ ) cannot provide a solution because they produce too little {}182{{H}}f and {}107{{P}}d relative to {}26{{A}}l and {}60{{F}}e. Lower-mass AGB stars cannot provide a solution because they produce too little {}26{{A}}l relative to {}107{{P}}d and {}182{{H}}f. A self-consistent solution may be found for AGB stars with masses in between (4–5.5 {M}ȯ ), provided that HBB is stronger than in our models and the {}13{{C}}(α, n){}16{{O}} neutron source is mildly activated. If stars of {{M}}< 5.5 {M}ȯ are the source of the radioactive nuclides, then some basis for their existence in proto-solar clouds needs to be explored, given that the stellar lifetimes are longer than the molecular cloud lifetimes.

  8. The extended molecular envelope of the asymptotic giant branch star π1 Gruis as seen by ALMA. I. Large-scale kinematic structure and CO excitation properties

    Science.gov (United States)

    Doan, L.; Ramstedt, S.; Vlemmings, W. H. T.; Höfner, S.; De Beck, E.; Kerschbaum, F.; Lindqvist, M.; Maercker, M.; Mohamed, S.; Paladini, C.; Wittkowski, M.

    2017-09-01

    Context. The S-type asymptotic giant branch (AGB) star π1 Gru has a known companion at a separation of 2.̋7 (≈400 AU). Previous observations of the circumstellar envelope (CSE) show strong deviations from spherical symmetry. The envelope structure, including an equatorial torus and a fast bipolar outflow, is rarely seen in the AGB phase and is particularly unexpected in such a wide binary system. Therefore a second, closer companion has been suggested, but the evidence is not conclusive. Aims: The aim is to make a 3D model of the CSE and to constrain the density and temperature distribution using new spatially resolved observations of the CO rotational lines. Methods: We have observed the J = 3-2 line emission from 12CO and 13CO using the compact arrays of the Atacama Large Millimeter/submillimeter Array (ALMA). The new ALMA data, together with previously published 12CO J = 2-1 data from the Submillimeter Array (SMA), and the 12CO J = 5-4 and J = 9-8 lines observed with Herschel/Heterodyne Instrument for the Far-Infrared (HIFI), is modeled with the 3D non-LTE radiative transfer code SHAPEMOL. Results: The data analysis clearly confirms the torus-bipolar structure. The 3D model of the CSE that satisfactorily reproduces the data consists of three kinematic components: a radially expanding torus with velocity slowly increasing from 8 to 13 km s-1 along the equator plane; a radially expanding component at the center with a constant velocity of 14 km s-1; and a fast, bipolar outflow with velocity proportionally increasing from 14 km s-1 at the base up to 100 km s-1 at the tip, following a linear radial dependence. The results are used to estimate an average mass-loss rate during the creation of the torus of 7.7 × 10-7 M⊙ yr-1. The total mass and linear momentum of the fast outflow are estimated at 7.3 × 10-4 M⊙ and 9.6 × 1037 g cm s-1, respectively. The momentum of the outflow is in excess (by a factor of about 20) of what could be generated by radiation

  9. A proposed direct measurement of cross section at Gamow window for key reaction $^{19}$F($p$,$\\alpha$)$^{16}$O in Asymptotic Giant Branch stars with a planned accelerator in CJPL

    CERN Document Server

    He, J J; Ma, S B; Hu, J; Zhang, L Y; Fu, C B; Zhang, N T; Lian, G; Su, J; Li, Y J; Yan, S Q; Shen, Y P; Hou, S Q; Jia, B L; Zhang, T; Zhang, X P; Guo, B; Kubono, S; Liu, W P

    2016-01-01

    In 2014, the National Natural Science Foundation of China (NSFC) approved the Jinping Underground Nuclear Astrophysics laboratory (JUNA) project, which aims at direct cross-section measurements of four key stellar nuclear reactions right down to the Gamow windows. In order to solve the observed fluorine overabundances in Asymptotic Giant Branch (AGB) stars, measuring the key $^{19}$F($p$,$\\alpha$)$^{16}$O reaction at effective burning energies (i.e., at Gamow window) is established as one of the scientific research sub-projects. The present paper describes this sub-project in details, including motivation, status, experimental setup, yield and background estimation, aboveground test, as well as other relevant reactions.

  10. STELLAR METALLICITIES AND KINEMATICS IN A GAS-RICH DWARF GALAXY : FIRST CALCIUM TRIPLET SPECTROSCOPY OF RED GIANT BRANCH STARS IN WLM

    NARCIS (Netherlands)

    Leaman, Ryan; Cole, Andrew A.; Venn, Kim A.; Tolstoy, Eline; Irwin, Mike J.; Szeifert, Thomas; Skillman, Evan D.; McConnachie, Alan W.

    2009-01-01

    We present the first determination of the radial velocities and metallicities of 78 red giant stars in the isolated dwarf irregular galaxy WLM. Observations of the calcium II triplet in these stars were made with FORS2 at the VLT-UT2 in two separated fields of view in WLM, and the [Fe/H] values were

  11. Rapidly rotating red giants

    CERN Document Server

    Gehan, Charlotte; Michel, Eric

    2016-01-01

    Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, which behave as pressure modes in the convective envelope and as gravity modes in the radiative core. Mixed modes thus directly probe red giant cores, and allow in particular the study of their mean core rotation. The high-quality data obtained by CoRoT and Kepler satellites represent an unprecedented perspective to obtain thousands of measurements of red giant core rotation, in order to improve our understanding of stellar physics in deep stellar interiors. We developed an automated method to obtain such core rotation measurements and validated it for stars on the red giant branch. In this work, we particularly focus on the specific application of this method to red giants having a rapid core rotation. They show complex spectra where it is tricky to disentangle rotational splittings from mixed-mode period spacings. We demonstrate that the method based on the id...

  12. Giant Planets

    CERN Document Server

    Guillot, Tristan

    2014-01-01

    We review the interior structure and evolution of Jupiter, Saturn, Uranus and Neptune, and giant exoplanets with particular emphasis on constraining their global composition. Compared to the first edition of this review, we provide a new discussion of the atmospheric compositions of the solar system giant planets, we discuss the discovery of oscillations of Jupiter and Saturn, the significant improvements in our understanding of the behavior of material at high pressures and the consequences for interior and evolution models. We place the giant planets in our Solar System in context with the trends seen for exoplanets.

  13. The Horizontal Branch of the Sculptor Dwarf galaxy

    CERN Document Server

    Salaris, Maurizio; Tolstoy, Eline; Fiorentino, Giuliana; Cassisi, Santi

    2013-01-01

    We have performed the first detailed simulation of the horizontal branch of the Sculptor dwarf spheroidal galaxy by means of synthetic modelling techniques,taking consistently into account the star formation history and metallicity evolution as determined from the main sequence and red giant branch spectroscopic observations. The only free parameter in the whole analysis is the integrated mass loss of red giant branch stars. This is the first time that synthetic horizontal branch models, consistent with the complex star formation history of a galaxy, are calculated and matched to the observations. We find that the metallicity range covered by the star formation history, as constrained by observations, plus a simple mass loss law, enable us to cover both the full magnitude and colour range of HB stars. In addition the number count distribution along the observed horizontal branch, can be also reproduced, provided that the red giant branch mass loss is mildly metallicity dependent, with a very small dispersion ...

  14. The Horizontal Branch of the Sculptor Dwarf galaxy

    NARCIS (Netherlands)

    Salaris, Maurizio; Boer, Thomas de; Tolstoy, Eline; Fiorentino, Giuliana; Cassisi, Santi

    2013-01-01

    We have performed the first detailed simulation of the horizontal branch of the Sculptor dwarf spheroidal galaxy by means of synthetic modelling techniques, taking consistently into account the star formation history and metallicity evolution as determined from the main sequence and red giant branch

  15. Lithium-Rich Giants in Globular Clusters

    CERN Document Server

    Kirby, Evan N; Zhang, Andrew J; Hong, Jerry; Guo, Michelle; Guo, Rachel; Cohen, Judith G; Cunha, Katia

    2016-01-01

    Although red giants deplete lithium on their surfaces, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron-Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2 +/- 0.1)% for the RGB, (1.6 +/- 1.1)% for the AGB, and (0.3 +/- 0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propo...

  16. Transforming giants.

    Science.gov (United States)

    Kanter, Rosabeth Moss

    2008-01-01

    Large corporations have long been seen as lumbering, inflexible, bureaucratic--and clueless about global developments. But recently some multinationals seem to be transforming themselves: They're engaging employees, moving quickly, and introducing innovations that show true connection with the world. Harvard Business School's Kanter ventured with a research team inside a dozen global giants--including IBM, Procter & Gamble, Omron, CEMEX, Cisco, and Banco Real--to discover what has been driving the change. After conducting more than 350 interviews on five continents, she and her colleagues came away with a strong sense that we are witnessing the dawn of a new model of corporate power: The coordination of actions and decisions on the front lines now appears to stem from widely shared values and a sturdy platform of common processes and technology, not from top-down decrees. In particular, the values that engage the passions of far-flung workforces stress openness, inclusion, and making the world a better place. Through this shift in what might be called their guidance systems, the companies have become as creative and nimble as much smaller ones, even while taking on social and environmental challenges of a scale that only large enterprises could attempt. IBM, for instance, has created a nonprofit partnership, World Community Grid, through which any organization or individual can donate unused computing power to research projects and see what is being done with the donation in real time. IBM has gained an inspiring showcase for its new technology, helped business partners connect with the company in a positive way, and offered individuals all over the globe the chance to contribute to something big.

  17. Giant Cell Arteritis

    Science.gov (United States)

    Giant cell arteritis is a disorder that causes inflammation of your arteries, usually in the scalp, neck, and arms. ... arteries, which keeps blood from flowing well. Giant cell arteritis often occurs with another disorder called polymyalgia ...

  18. Rotation of Giant Stars

    CERN Document Server

    Kissin, Yevgeni

    2015-01-01

    The internal rotation of post-main sequence stars is investigated, in response to the convective pumping of angular momentum toward the stellar core, combined with a tight magnetic coupling between core and envelope. The spin evolution is calculated using model stars of initial mass 1, 1.5 and $5\\,M_\\odot$, taking into account mass loss on the giant branches and the partitioning of angular momentum between the outer and inner envelope. We also include the deposition of orbital angular momentum from a sub-stellar companion, as influenced by tidal drag as well as the excitation of orbital eccentricity by a fluctuating gravitational quadrupole moment. A range of angular velocity profiles $\\Omega(r)$ is considered in the deep convective envelope, ranging from solid rotation to constant specific angular momentum. We focus on the backreaction of the Coriolis force on the inward pumping of angular momentum, and the threshold for dynamo action in the inner envelope. Quantitative agreement with measurements of core ro...

  19. Lithium-rich Giants in Globular Clusters

    Science.gov (United States)

    Kirby, Evan N.; Guhathakurta, Puragra; Zhang, Andrew J.; Hong, Jerry; Guo, Michelle; Guo, Rachel; Cohen, Judith G.; Cunha, Katia

    2016-03-01

    Although red giants deplete lithium on their surfaces, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron-Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2 ± 0.1)% for the RGB, (1.6 ± 1.1)% for the AGB, and (0.3 ± 0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propose the following origin for Li enrichment: (1) All luminous giants experience a brief phase of Li enrichment at the He core flash. (2) All post-RGB stars with binary companions on the lower RGB will engage in mass transfer. This scenario predicts that 0.1% of lower RGB stars will appear Li-rich due to mass transfer from a recently Li-enhanced companion. This frequency is at the lower end of our confidence interval. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  20. LITHIUM-RICH GIANTS IN GLOBULAR CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Evan N.; Cohen, Judith G. [California Institute of Technology, 1200 E. California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Guhathakurta, Puragra [UCO/Lick Observatory and Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Zhang, Andrew J. [The Harker School, 500 Saratoga Avenue, San Jose, CA 95129 (United States); Hong, Jerry [Palo Alto High School, 50 Embarcadero Road, Palo Alto, CA, 94301 (United States); Guo, Michelle [Stanford University, 450 Serra Mall, Stanford, CA 94305 (United States); Guo, Rachel [Irvington High School, 41800 Blacow Road, Fremont, CA 94538 (United States); Cunha, Katia [Observatório Nacional, São Cristóvão Rio de Janeiro (Brazil)

    2016-03-10

    Although red giants deplete lithium on their surfaces, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron–Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2 ± 0.1)% for the RGB, (1.6 ± 1.1)% for the AGB, and (0.3 ± 0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propose the following origin for Li enrichment: (1) All luminous giants experience a brief phase of Li enrichment at the He core flash. (2) All post-RGB stars with binary companions on the lower RGB will engage in mass transfer. This scenario predicts that 0.1% of lower RGB stars will appear Li-rich due to mass transfer from a recently Li-enhanced companion. This frequency is at the lower end of our confidence interval.

  1. Giant osteoblastoma of temporal bone: case report

    Directory of Open Access Journals (Sweden)

    FIGUEIREDO EBERVAL GADELHA

    1998-01-01

    Full Text Available Benign osteoblastoma is an uncommon bone tumor accounting for approximately 1% of all bone tumors. There are only 35 cases of skull osteoblastoma reported in the literature. We describe the case of a 23 year old male with a giant osteoblastoma of temporal bone submitted to a total removal of the tumor after an effective embolization of all external carotid branches. The authors discuss diagnostic and management aspects of this uncommon skull tumor.

  2. Branched polynomial covering maps

    DEFF Research Database (Denmark)

    Hansen, Vagn Lundsgaard

    1999-01-01

    A Weierstrass polynomial with multiple roots in certain points leads to a branched covering map. With this as the guiding example, we formally define and study the notion of a branched polynomial covering map. We shall prove that many finite covering maps are polynomial outside a discrete branch...

  3. Branched polynomial covering maps

    DEFF Research Database (Denmark)

    Hansen, Vagn Lundsgaard

    2002-01-01

    A Weierstrass polynomial with multiple roots in certain points leads to a branched covering map. With this as the guiding example, we formally define and study the notion of a branched polynomial covering map. We shall prove that many finite covering maps are polynomial outside a discrete branch...

  4. Giant hepatic regenerative nodules in Alagille syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Jordan B. [Lewis Katz School of Medicine at Temple University, Department of Radiology, Temple University Hospital, Philadelphia, PA (United States); Bellah, Richard D.; Anupindi, Sudha A. [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); Maya, Carolina [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Pawel, Bruce R. [University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA (United States); The Children' s Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, Philadelphia, PA (United States)

    2017-02-15

    Children with Alagille syndrome undergo surveillance radiologic examinations as they are at risk for developing cirrhosis and hepatocellular carcinoma. There is limited literature on the imaging of liver masses in Alagille syndrome. We report the ultrasound (US) and magnetic resonance imaging (MRI) appearances of incidental benign giant hepatic regenerative nodules in this population. To describe the imaging findings of giant regenerative nodules in patients with Alagille syndrome. A retrospective search of the hospital database was performed to find all cases of hepatic masses in patients with Alagille syndrome during a 10-year period. Imaging, clinical charts, laboratory data and available pathology were reviewed and analyzed and summarized for each patient. Twenty of 45 patients with confirmed Alagille syndrome had imaging studies. Of those, we identified six with giant focal liver masses. All six patients had large central hepatic masses that were remarkably similar on US and MRI, in addition to having features of cirrhosis. In each case, the mass was located in hepatic segment VIII and imaging showed the mass splaying the main portal venous branches at the hepatic hilum, as well as smaller portal and hepatic venous branches coursing through them. On MRI, signal intensity of the mass was isointense to liver on T1-weighted sequences in four of six patients, but hyperintense on T1 in two of six patients. In all six cases, the mass was hypointense on T2- weighted sequences. The mass post-contrast was isointense to adjacent liver in all phases in five the cases. Five out of six patients had pathological correlation demonstrating preserved ductal architecture confirming the final diagnosis of a regenerative nodule. Giant hepatic regenerative nodules with characteristic US and MR features can occur in patients with Alagille syndrome with underlying cirrhosis. Recognizing these lesions as benign giant hepatic regenerative nodules should, thereby, mitigate any need for

  5. Constructing stable 3D hydrodynamical models of giant stars

    Science.gov (United States)

    Ohlmann, Sebastian T.; Röpke, Friedrich K.; Pakmor, Rüdiger; Springel, Volker

    2017-02-01

    Hydrodynamical simulations of stellar interactions require stable models of stars as initial conditions. Such initial models, however, are difficult to construct for giant stars because of the wide range in spatial scales of the hydrostatic equilibrium and in dynamical timescales between the core and the envelope of the giant. They are needed for, e.g., modeling the common envelope phase where a giant envelope encompasses both the giant core and a companion star. Here, we present a new method of approximating and reconstructing giant profiles from a stellar evolution code to produce stable models for multi-dimensional hydrodynamical simulations. We determine typical stellar stratification profiles with the one-dimensional stellar evolution code mesa. After an appropriate mapping, hydrodynamical simulations are conducted using the moving-mesh code arepo. The giant profiles are approximated by replacing the core of the giant with a point mass and by constructing a suitable continuation of the profile to the center. Different reconstruction methods are tested that can specifically control the convective behaviour of the model. After mapping to a grid, a relaxation procedure that includes damping of spurious velocities yields stable models in three-dimensional hydrodynamical simulations. Initially convectively stable configurations lead to stable hydrodynamical models while for stratifications that are convectively unstable in the stellar evolution code, simulations recover the convective behaviour of the initial model and show large convective plumes with Mach numbers up to 0.8. Examples are shown for a 2 M⊙ red giant and a 0.67 M⊙ asymptotic giant branch star. A detailed analysis shows that the improved method reliably provides stable models of giant envelopes that can be used as initial conditions for subsequent hydrodynamical simulations of stellar interactions involving giant stars.

  6. Evolution and nucleosynthesis in low mass Asymptotic Giant Branch stars

    CERN Document Server

    Cristallo, S

    2008-01-01

    People usually smile when astrophysicists assert that we are sons of the stars, but human life confirms this sentence: about 65% of the mass of our body is made up of oxygen, carbon occurs in all organic life and is the basis of organic chemistry, nitrogen is an essential part of amino acids and nucleic acids, calcium is a major component of our bones. Moreover, phosphorus plays a major role in biological molecules such as DNA and RNA (where the chemical codes of life is written) and our blood carries oxygen to tissues by means of the hemoglobin (an iron pigment of red blood cells). All these elements have been created in stars. I just list some examples related to human body, but also common element such as aluminum, nickel, gold, silver and lead come from a pristine generation of stars. The abundances in the Solar System are in fact due to the mixing of material ejected from stars that polluted the Universe in different epochs before the Sun formation, occurred about 5 billion years ago, after the gravitati...

  7. The astrosphere of the asymptotic giant branch star CIT 6

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Raghvendra [Jet Propulsion Laboratory, MS 183-900, California Institute of Technology, Pasadena, CA 91109 (United States); Mack-Crane, Galen P., E-mail: sahai@jpl.nasa.gov [Department of Physics, Occidental College, Los Angeles, CA 90041 (United States)

    2014-10-01

    We have discovered two extended half-ring structures in a far-ultraviolet image taken with the GALEX satellite of the well-known mass-losing carbon star CIT 6 (RW LMi). The northern (southern) ring is brighter (fainter) with a diameter of ∼15' (∼18'). These structures most likely represent the astrosphere resulting from the shock interaction of CIT 6's molecular wind with the warm interstellar medium (ISM), as it moves through the latter. These data provide a direct estimate of the size of CIT 6's circumstellar envelope that is a factor ∼20 larger than previous estimates based on CO millimeter-wave line data. We find that CIT 6 has been undergoing heavy mass-loss for at least 93,000 yr and the total envelope mass is 0.29 M {sub ☉} or larger, assuming a constant mass-loss rate of 3.2 × 10{sup –6} M {sub ☉} yr{sup –1}. Assuming that the shock front has reached a steady state and CIT 6's motion relative to the ISM is in the sky plane, we measure the termination-shock standoff distance directly from the image and find that CIT 6 is moving at a speed of about ≳39 (0.17 cm{sup –3}/n {sub ISM}){sup 1/2} km s{sup –1} through the ISM around it. However, comparisons with published numerical simulations and analytical modeling shows that CIT 6's forward shock (the northern ring) departs from the parabolic shape expected in steady state. We discuss several possible explanations for this departureþ.

  8. The Astrosphere of the Asymptotic Giant Branch Star Irc+10216

    CERN Document Server

    Sahai, Raghvendra

    2010-01-01

    We have discovered a very extended shock structure (i.e., with a diameter of about 24 arcmin) surrounding the well-known carbon star IRC+10216 in ultraviolet images taken with the GALEX satellite. We conclude that this structure results from the interaction of IRC+10216's molecular wind with the interstellar medium (ISM), as it moves through the latter. All important structural features expected from theoretical models of such interactions are identified: the termination shock, the astrosheath, the astropause, the bowshock, and an astrotail (with vortices). The extent of the astropause provides new lower limits to the envelope age (69,000 years) and mass (1.4 solar masses, for a mass-loss rate of 2 x 10^(-5) solar masses/year). From the termination-shock standoff distance, we find that IRC+10216 is moving at a speed of about > 91 km/s [1 cm^(-3)/n_(ISM)]^1/2 through the local ISM.

  9. The Astrosphere of the Asymptotic Giant Branch Star CIT 6

    Science.gov (United States)

    Sahai, Raghvendra; Mack-Crane, Galen P.

    2014-10-01

    We have discovered two extended half-ring structures in a far-ultraviolet image taken with the GALEX satellite of the well-known mass-losing carbon star CIT 6 (RW LMi). The northern (southern) ring is brighter (fainter) with a diameter of ~15' (~18'). These structures most likely represent the astrosphere resulting from the shock interaction of CIT 6's molecular wind with the warm interstellar medium (ISM), as it moves through the latter. These data provide a direct estimate of the size of CIT 6's circumstellar envelope that is a factor ~20 larger than previous estimates based on CO millimeter-wave line data. We find that CIT 6 has been undergoing heavy mass-loss for at least 93,000 yr and the total envelope mass is 0.29 M ⊙ or larger, assuming a constant mass-loss rate of 3.2 × 10-6 M ⊙ yr-1. Assuming that the shock front has reached a steady state and CIT 6's motion relative to the ISM is in the sky plane, we measure the termination-shock standoff distance directly from the image and find that CIT 6 is moving at a speed of about gsim39 (0.17 cm-3/n ISM)1/2 km s-1 through the ISM around it. However, comparisons with published numerical simulations and analytical modeling shows that CIT 6's forward shock (the northern ring) departs from the parabolic shape expected in steady state. We discuss several possible explanations for this departure.

  10. The astrosphere of the Asymptotic Giant Branch star CIT 6

    CERN Document Server

    Sahai, Raghvendra

    2014-01-01

    We have discovered two extended half-ring structures in a far-ultraviolet image taken with the GALEX satellite of the well-known mass-losing carbon star CIT 6 (RW LMi). The northern (southern) ring is brighter (fainter) with a diameter of about 15 arcmin (18 arcmin). These structures most likely represent the astrosphere resulting from the shock interaction of CIT 6's molecular wind with the Warm Interstellar Medium, as it moves through the latter. These data provide a direct estimate of the size of CIT 6's circumstellar envelope that is a factor ~20 larger than previous estimates based on CO millimeter-wave line data. We find that CIT 6 has been undergoing heavy mass-loss for at least 93,000 yr and the total envelope mass is 0.29 Msun or larger, assuming a constant mass-loss rate of 3.2 x 10^(-6) Msun/yr. Assuming that the shock front has reached a steady-state and CIT 6's motion relative to the ISM is in the sky-plane, we measure the termination-shock standoff distance directly from the image and find that ...

  11. The s-Process in Rotating Asymptotic Giant Branch Stars

    CERN Document Server

    Herwig, F; Lugaro, M

    2003-01-01

    (abridged) We model the nucleosynthesis during the thermal pulse phase of a rotating, solar metallicity AGB star of 3M_sun. Rotationally induced mixing during the thermal pulses produces a layer (~2E-5M_sun) on top of the CO-core where large amounts of protons and C12 co-exist. We follow the abundance evolution in this layer, in particular that of the neutron source C13 and of the neutron poison N14. In our AGB model mixing persists during the entire interpulse phase due to the steep angular velocity gradient at the core-envelope interface. We follow the neutron production during the interpulse phase, and find a resulting maximum neutron exposure of tau_max =0.04 mbarn^-1, which is too small to produce any significant s-process. In parametric models, we then investigate the combined effects of diffusive overshooting from the convective envelope and rotationally induced mixing. Models with overshoot and weaker interpulse mixing - as perhaps expected from more slowly rotating stars - yield larger neutron exposu...

  12. INTERRUPTED MASS-LOSS ON THE ASYMPTOTIC GIANT BRANCH

    NARCIS (Netherlands)

    ZIJLSTRA, AA; LOUP, C; WATERS, LBFM; DEJONG, T

    1992-01-01

    We show that mass loss on the AGB is not a continuous process. Episodes of low mass loss rate, already known for carbon stars, are found to occur in oxygen-rich stars as well, suggesting that they constitute a general phenomenon. We propose that the mass loss depends on the phase of the thermal puls

  13. Giant Cell Arteritis

    Science.gov (United States)

    ... Cryopyrin-Associated Autoinflammatory Syndrome (CAPS) (Juvenile) Dermatomyositis (Juvenile) Familial Mediterranean Fever (Juvenile) Fibromyalgia Giant Cell Arteritis Glucocorticoid-induced Osteoperosis ...

  14. Nanodielectrics with giant permittivity

    Indian Academy of Sciences (India)

    S K Saha

    2008-06-01

    Nanodielectrics is an emerging area of research because of its potential application in energy storage and transducers. One-dimensional metallic nanostructures with localized electronic wave functions show giant dielectric constant. Following the prediction, during the last couple of years we have investigated the effect of giant permittivity in one-dimensional systems of conventional metals and conjugated polymer chains. In this article, we have tried to summarize the works on giant permittivity and finally the fabrication of nanocapacitor using metal nanowires, which shows giant permittivity is also discussed.

  15. Asteroseismology of 1523 misclassified red giants using Kepler data

    DEFF Research Database (Denmark)

    Yu, Jie; Huber, Daniel; Bedding, Timothy R.

    2016-01-01

    We analysed solar-like oscillations in 1523 Kepler red giants which have previously been misclassified as subgiants, with predicted nu(max) values [based on the Kepler Input Catalogue (KIC)] between 280 and 700 mu Hz. We report the discovery of 626 new oscillating red giants in our sample......, in addition to 897 oscillators that were previously characterized by Hekker et al. from one quarter of Kepler data. Our sample increases the known number of oscillating low-luminosity red giants by 26 per cent (up to similar to 1900 stars). About three quarters of our sample are classified as ascending red...... giant branch stars, while the remainder are red-clump stars. A novel scheme was applied to determine Delta nu for 108 stars with nu(max) close to the Nyquist frequency (240 mu Hz

  16. Peripheral giant cell granuloma

    Directory of Open Access Journals (Sweden)

    Padam Narayan Tandon

    2012-01-01

    Full Text Available Peripheral giant cell granuloma or the so-called "giant cell epulis" is the most common oral giant cell lesion. It normally presents as a soft tissue purplish-red nodule consisting of multinucleated giant cells in a background of mononuclear stromal cells and extravasated red blood cells. This lesion probably does not represent a true neoplasm, but rather may be reactive in nature, believed to be stimulated by local irritation or trauma, but the cause is not certainly known. This article reports a case of peripheral giant cell granuloma arising at the maxillary anterior region in a 22-year-old female patient. The lesion was completely excised to the periosteum level and there is no residual or recurrent swelling or bony defect apparent in the area of biopsy after a follow-up period of 6 months.

  17. A Superwind from Early Post-Red Giant Stars?

    CERN Document Server

    Soker, N; Rood, R T; Harpaz, A; Soker, Noam; Catelan, Marcio; Rood, Robert T.; Harpaz, Amos

    2001-01-01

    We suggest that the gap observed at 20,000 K in the horizontal branches of several Galactic globular clusters is caused by a small amount of extra mass loss which occurs when stars start to "peel off" the red giant branch (RGB), i.e., when their effective temperature starts to increase, even though they may still be on the RGB. We show that the envelope structure of RGB stars which start to peel off is similar to that of late asymptotic giant branch stars known to have a super-wind phase. An analogous super-wind in the RGB peel-off stars could easily lead to the observed gap in the distribution of the hottest HB stars.

  18. Melons are branched polymers

    CERN Document Server

    Gurau, Razvan

    2013-01-01

    Melonic graphs constitute the family of graphs arising at leading order in the 1/N expansion of tensor models. They were shown to lead to a continuum phase, reminiscent of branched polymers. We show here that they are in fact precisely branched polymers, that is, they possess Hausdorff dimension 2 and spectral dimension 4/3.

  19. Coherent branching feature bisimulation

    Directory of Open Access Journals (Sweden)

    Tessa Belder

    2015-04-01

    Full Text Available Progress in the behavioral analysis of software product lines at the family level benefits from further development of the underlying semantical theory. Here, we propose a behavioral equivalence for feature transition systems (FTS generalizing branching bisimulation for labeled transition systems (LTS. We prove that branching feature bisimulation for an FTS of a family of products coincides with branching bisimulation for the LTS projection of each the individual products. For a restricted notion of coherent branching feature bisimulation we furthermore present a minimization algorithm and show its correctness. Although the minimization problem for coherent branching feature bisimulation is shown to be intractable, application of the algorithm in the setting of a small case study results in a significant speed-up of model checking of behavioral properties.

  20. Quantum Giant Magnons

    CERN Document Server

    Zarembo, K

    2008-01-01

    The giant magnons are classical solitons of the O(N) sigma-model, which play an important role in the AdS/CFT correspondence. We study quantum giant magnons first at large N and then exactly using Bethe Ansatz, where giant magnons can be interpreted as holes in the Fermi sea. We also identify a solvable limit of Bethe Ansatz in which it describes a weakly-interacting Bose gas at zero temperature. The examples include the O(N) model at large N, weakly interacting non-linear Schrodinger model, and nearly isotropic XXZ spin chain in the magnetic field.

  1. Dynamos of giant planets

    CERN Document Server

    Busse, F H; 10.1017/S1743921307000920

    2009-01-01

    Possibilities and difficulties of applying the theory of magnetic field generation by convection flows in rotating spherical fluid shells to the Giant Planets are outlined. Recent progress in the understanding of the distribution of electrical conductivity in the Giant Planets suggests that the dynamo process occurs predominantly in regions of semiconductivity. In contrast to the geodynamo the magnetic field generation in the Giant Planets is thus characterized by strong radial conductivity variations. The importance of the constraint on the Ohmic dissipation provided by the planetary luminosity is emphasized. Planetary dynamos are likely to be of an oscillatory type, although these oscillations may not be evident from the exterior of the planets.

  2. Giant Cell Fibroma

    OpenAIRE

    Tahere Nosratzehi; Lale Maleki

    2013-01-01

    Giant cell fibroma is a fibrous tumor which represents about 2 to 5% of all oral fibrotic proliferations. Compared to traumatic fibroma, giant (traumatic fibroma or irritation fibroma) cell fibroma occurs at a younger age. In about 60% of the cases the lesion is diagnosed within the first three decades of life and is slightly more in women. 50% of the cases is observed in the gum and will appear as a nodule with a papillary surface [1]. The giant cell fibroma is treated by conservative excisi...

  3. Collateral branching of long-distance cortical projections in monkey.

    Science.gov (United States)

    Rockland, Kathleen S

    2013-12-15

    Collateralization of individual cortical axons is well documented for rodents but less so for monkeys, where double retrograde tracer experiments have tended to find only small numbers of neurons projecting to two different injection sites. Evidence from both double label and single axon studies, however, suggests that in specific projection systems the number of neurons with collateralized axons can be 10% or greater. These include feedback projections from temporal areas (but less so those from V4 and MT/V5). Single-axon analyses show that many parietal neurons branch to multiple targets. Except for giant Meynert cells in area V1, feedforward projections from early visual areas have only a small number of neurons with branching axons. Why only some neurons collateralize, what determines branch points and projection foci, and how this impacts network organization are largely unknown. Deciphering the branching code might offer new perspectives on space-time organization at the network level.

  4. Giant distal humeral geode

    Energy Technology Data Exchange (ETDEWEB)

    Maher, M.M. [Department of Radiology, Mater Misericordiae Hospital, Dublin (Ireland); Department of Radiology, St. Vincent' s Hospital, Elm Park, Dublin 4 (Ireland); Kennedy, J.; Hynes, D. [Department of Orthopaedics, Mater Misericordiae Hospital, Dublin (Ireland); Murray, J.G.; O' Connell, D. [Department of Radiology, Mater Misericordiae Hospital, Dublin (Ireland)

    2000-03-30

    We describe the imaging features of a giant geode of the distal humerus in a patient with rheumatoid arthritis, which presented initially as a pathological fracture. The value of magnetic resonance imaging in establishing this diagnosis is emphasized. (orig.)

  5. Metaphyseal giant cell tumor

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, L.F.; Hemais, P.M.P.G.; Aymore, I.L.; Carmo, M.C.R. do; Cunha, M.E.P.R. da; Resende, C.M.C.

    Three cases of metaphyseal giant cell tumor are presented. A review of the literature is done, demostrating the lesion is rare and that there are few articles about it. Age incidence and characteristics of the tumor are discussed.

  6. The Giant Cell.

    Science.gov (United States)

    Stockdale, Dennis

    1998-01-01

    Provides directions for the construction of giant plastic cells, including details for building and installing the organelles. Also contains instructions for preparing the ribosomes, nucleolus, nucleus, and mitochondria. (DDR)

  7. Seismology of Giant Planets

    CERN Document Server

    Gaulme, Patrick; Schmider, Francois-Xavier; Guillot, Tristan

    2014-01-01

    Seismology applied to giant planets could drastically change our understanding of their deep interiors, as it has happened with the Earth, the Sun, and many main-sequence and evolved stars. The study of giant planets' composition is important for understanding both the mechanisms enabling their formation and the origins of planetary systems, in particular our own. Unfortunately, its determination is complicated by the fact that their interior is thought not to be homogeneous, so that spectroscopic determinations of atmospheric abundances are probably not representative of the planet as a whole. Instead, the determination of their composition and structure must rely on indirect measurements and interior models. Giant planets are mostly fluid and convective, which makes their seismology much closer to that of solar-like stars than that of terrestrial planets. Hence, helioseismology techniques naturally transfer to giant planets. In addition, two alternative methods can be used: photometry of the solar light ref...

  8. Giant magnetostrictive materials

    Institute of Scientific and Technical Information of China (English)

    LIU JingHua; JIANG ChengBao; XU HuiBin

    2012-01-01

    Giant magnetostrictive materials are a kind of functional materials developed since 1970s,known as their large magnetostrain and high energy density.In this paper,an introduction of magnetosttiction and the history of magnetostrictive materials are described firstly.Then we review the recent developments of both rare earth and non-rare earth magnetostrictive materials.Finally,the tendency of developing new giant magnetostrictive materials is presented.

  9. Red giant seismology: Observations

    Directory of Open Access Journals (Sweden)

    Mosser B.

    2013-03-01

    Full Text Available The CoRoT and Kepler missions provide us with thousands of red-giant light curves that allow a very precise asteroseismic study of these objects. Before CoRoT and Kepler, the red-giant oscillation patterns remained obscure. Now, these spectra are much more clear and unveil many crucial interior structure properties. For thousands of red giants, we can derive from seismic data precise estimates of the stellar mass and radius, the evolutionary status of the giants (with a clear difference between clump and RGB stars, the internal differential rotation, the mass loss, the distance of the stars... Analyzing this amount of information is made easy by the identification of the largely homologous red-giant oscillation patterns. For the first time, both pressure and mixed mode oscillation patterns can be precisely depicted. The mixed-mode analysis allows us, for instance, to probe directly the stellar core. Fine details completing the red-giant oscillation pattern then provide further information on the interior structure, including differential rotation.

  10. Inclusion of horizontal branch stars in the derivation of star formation histories of dwarf galaxies: The Carina dSph

    NARCIS (Netherlands)

    Savino, Alessandro; Salaris, Maurizio; Tolstoy, Eline

    2015-01-01

    We present a detailed analysis of the horizontal branch of the Carina dwarf spheroidal galaxy by means of synthetic modelling techniques, taking consistently into account the star formation history and metallicity evolution as determined from main sequence and red giant branch spectroscopic

  11. Branching processes in biology

    CERN Document Server

    Kimmel, Marek

    2015-01-01

    This book provides a theoretical background of branching processes and discusses their biological applications. Branching processes are a well-developed and powerful set of tools in the field of applied probability. The range of applications considered includes molecular biology, cellular biology, human evolution and medicine. The branching processes discussed include Galton-Watson, Markov, Bellman-Harris, Multitype, and General Processes. As an aid to understanding specific examples, two introductory chapters, and two glossaries are included that provide background material in mathematics and in biology. The book will be of interest to scientists who work in quantitative modeling of biological systems, particularly probabilists, mathematical biologists, biostatisticians, cell biologists, molecular biologists, and bioinformaticians. The authors are a mathematician and cell biologist who have collaborated for more than a decade in the field of branching processes in biology for this new edition. This second ex...

  12. Coherent branching feature bisimulation

    NARCIS (Netherlands)

    T. Belder (Tessa); M.H. ter Beek (Maurice); E.P. de Vink (Erik Peter)

    2015-01-01

    textabstractProgress in the behavioral analysis of software product lines at the family level benefits from further development of the underlying semantical theory. Here, we propose a behavioral equivalence for feature transition systems (FTS) generalizing branching bisimulation for labeled

  13. Koenigs function and branching processes

    CERN Document Server

    Chikilev, O G

    2001-01-01

    An explicit solution of time-homogeneous pure birth branching processes is described. It gives alternative extensions for the negative binomial distribution (branching processes with immigration) and for the Furry-Yule distribution (branching processes without immigration).

  14. Branched Polymer Revisited

    CERN Document Server

    Aoki, H; Kawai, H; Kitazawa, Y; Aoki, Hajime; Iso, Satoshi; Kawai, Hikaru; Kitazawa, Yoshihisa

    2000-01-01

    We show that correlation functions for branched polymers correspond to those for $\\phi^3$ theory with a single mass insertion, not those for the $\\phi^3$ theory themselves, as has been widely believed. In particular, the two-point function behaves as 1/p^4, not as 1/p^2. This behavior is consistent with the fact that the Hausdorff dimension of the branched polymer is four.

  15. Giant neurons in the macaque pulvinar: a distinct relay subpopulation

    Directory of Open Access Journals (Sweden)

    Kosuke Imura

    2007-07-01

    Full Text Available Calbindin positive (CB+ giant neurons are known to occur within the pulvinar nucleus in subhuman primates. Here, we demonstrate by combined retrograde tracing and immunocytochemistry that at least some of these are pulvinocortical relay neurons, and further report several distinctive features. First, in contrast with non-giant relay neurons, the giant neurons are often solitary and isolated from a main projection focus. The question thus arises of whether their cortical projections may be non-reciprocal or otherwise distinctive. Second, these neurons are positive for GluR4; but third, they are otherwise neurochemically heterogeneous, in that about one-third are positive for both parvalbumin (PV and CB. Presumably, these subpopulations are also functionally heterogeneous. These results provide further evidence for the idea of multiple, interleaved organizations within the pulvinar; and they imply that thalamocortical projections are more disparate than has yet been appreciated. Finally, we found that giant CB+ neurons have a distinctive meshwork of large, PV+ terminations, prominent at the first dendritic branch point. In size and location, these resemble inhibitory terminations from the zona incerta or anterior pretectal nucleus (APT, as recently described in higher order thalamic nuclei in rats. One can speculate that giant neurons in the macaque pulvinar participate in a layer 5-APT-thalamus (giant neuron extrareticular pathway, functionally distinct from the layer 6-reticular nucleus-thalamus network.

  16. Lithium and magnetic fields in giants. HD 232862 : a magnetic and lithium-rich giant star

    CERN Document Server

    Lèbre, A; Nascimento, J D do; Konstantinova-Antova, R; Kolev, D; Aurière, M; De Laverny, P; De Medeiros, J R

    2009-01-01

    We report the detection of an unusually high lithium content in HD 232862, a field giant classified as a G8II star, and hosting a magnetic field. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232862, KU Peg and HD 21018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also analysed Stokes V signatures, looking for a magnetic field on these giants. HD 232862, presents a very high abundance of lithium (ALi = 2.45 +/- 0.25 dex), far in excess of the theoretically value expected at this spectral type and for this luminosity class (i.e, G8II). The evolutionary stage of HD 232862 has been precised, and it suggests a mass in the lower part of the [1.0 Msun ; 3.5 Msun ] mass interval, likely 1.5 to 2.0 solar mass, at the bottom of the Red Giant Branch. Besides, a time variable Stokes V signature has...

  17. The origin of extreme horizontal branch stars

    CERN Document Server

    Dorman, B; O'Connell, R W; Dorman, Ben; Rood, Robert T; O'Connell, Robert W

    1995-01-01

    Strong mass loss on the red giant branch (RGB) can result in the formation of extreme horizontal branch (EHB) stars. The EHB stars spend most of their He core and shell burning phase at high temperatures and produce copious ultraviolet flux. They have very small hydrogen envelopes and occupy a small range in mass. We have computed evolutionary RGB models with mass loss for stars with a range of metallicities at initial masses < 1.1 Msun corresponding to populations ages between 12.5 and 14.5 Gyr. We used the Reimers formula to characterize mass loss, but investigated a larger range of the mass loss efficiency parameter, eta, than is common. To understand how the number of EHB stars varies with metallicity in a stellar population we considered how the zero-age horizontal branch (ZAHB) is populated. The range in eta producing EHB stars is comparable to that producing `mid-HB' stars. Somewhat surprisingly, neither the range nor magnitude of eta producing EHB stars varies much metallicity. In contrast, the ran...

  18. Giant dendritic carbonaceous particles in Soweto aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Wentzel, M.; Annegarn, H.J.; Helas, G.; Weinbruch, S.; Balogh, A.G.; Sithole, J.S. [Max Planck Institute of Chemistry, Mainz (Germany). Biogeochemistry Dept.

    1999-03-01

    Gravimetric analyses of aerosol filter samples from Soweto, southwest of Johannesburg, have revealed an anomalous mass-size distribution. Instead of the coal fire generated aerosol forming sub-micron aerosols as expected, most of the mass of the winter smoke is in particles greater than 3{mu}m aerodynamic diameter. A high-resolution scanning electron microscope was used to examine coarse and fine-mode aerosol fractions from two contrasting sites in the conurbation. Unanticipated giant carbonaceous conglomerates (10-100 {mu}m diameter), which comprise the bulk of the aerosol mass on the filters examined, were found. The outer shape of the conglomerates tends towards spherical, rather than the branched, chain-like structures of high-temperature soot. Internal structure varies from highly dendritic with 20-nm-wide branches, through a coarser sponge-like structure to an almost solid `melted toffee` irregular surface. Possible modes of formation of these conglomerates are discussed in terms of condensation aerosols conglomeration, and subsequent partial melting or solvent condensation. The occurrence of the giant carbonaceous conglomerates as a general feature of the Soweto winter atmosphere explains the anomalous size-mass distribution results from bulk filter analyses.

  19. Thermal Giant Gravitons

    CERN Document Server

    Armas, Jay; Obers, Niels A; Orselli, Marta; Pedersen, Andreas Vigand

    2012-01-01

    We study the giant graviton solution as the AdS_5 X S^5 background is heated up to finite temperature. The analysis employs the thermal brane probe technique based on the blackfold approach. We focus mainly on the thermal giant graviton corresponding to a thermal D3-brane probe wrapped on an S^3 moving on the S^5 of the background at finite temperature. We find several interesting new effects, including that the thermal giant graviton has a minimal possible value for the angular momentum and correspondingly also a minimal possible radius of the S^3. We compute the free energy of the thermal giant graviton in the low temperature regime, which potentially could be compared to that of a thermal state on the gauge theory side. Moreover, we analyze the space of solutions and stability of the thermal giant graviton and find that, in parallel with the extremal case, there are two available solutions for a given temperature and angular momentum, one stable and one unstable. In order to write down the equations of mot...

  20. Giant star seismology

    CERN Document Server

    Hekker, S

    2016-01-01

    The internal properties of stars in the red-giant phase undergo significant changes on relatively short timescales. Long near-interrupted high-precision photometric timeseries observations from dedicated space missions such as CoRoT and Kepler have provided seismic inferences of the global and internal properties of a large number of evolved stars, including red giants. These inferences are confronted with predictions from theoretical models to improve our understanding of stellar structure and evolution. Our knowledge and understanding of red giants have indeed increased tremendously using these seismic inferences, and we anticipate that more information is still hidden in the data. Unraveling this will further improve our understanding of stellar evolution. This will also have significant impact on our knowledge of the Milky Way Galaxy as well as on exo-planet host stars. The latter is important for our understanding of the formation and structure of planetary systems.

  1. Damage Tolerance Assessment Branch

    Science.gov (United States)

    Walker, James L.

    2013-01-01

    The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.

  2. Right bundle branch block

    DEFF Research Database (Denmark)

    Bussink, Barbara E; Holst, Anders Gaarsdal; Jespersen, Lasse

    2013-01-01

    AimsTo determine the prevalence, predictors of newly acquired, and the prognostic value of right bundle branch block (RBBB) and incomplete RBBB (IRBBB) on a resting 12-lead electrocardiogram in men and women from the general population.Methods and resultsWe followed 18 441 participants included.......5%/2.3% in women, P Right bundle branch block was associated with significantly...... increased all-cause and cardiovascular mortality in both genders with age-adjusted hazard ratios (HR) of 1.31 [95% confidence interval (CI), 1.11-1.54] and 1.87 (95% CI, 1.48-2.36) in the gender pooled analysis with little attenuation after multiple adjustment. Right bundle branch block was associated...

  3. The Frequency of Lithium-Rich Giants in Globular Clusters

    Science.gov (United States)

    Kirby, Evan N.; Guhathakurta, Puragra; Zhang, Andrew J.; Hong, Jerry; Guo, Michelle; Guo, Rachel; Cohen, Judith G.; Cunha, Katia M. L.

    2016-01-01

    Although red giants destroy lithium, some giants are Li-rich. Intermediate-mass asymptotic giant branch (AGB) stars can generate Li through the Cameron-Fowler conveyor, but the existence of Li-rich, low-mass red giant branch (RGB) stars is puzzling. Globular clusters are the best sites to examine this phenomenon because it is straightforward to determine membership in the cluster and to identify the evolutionary state of each star. In 72 hours of Keck/DEIMOS exposures in 25 clusters, we found four Li-rich RGB and two Li-rich AGB stars. There were 1696 RGB and 125 AGB stars with measurements or upper limits consistent with normal abundances of Li. Hence, the frequency of Li-richness in globular clusters is (0.2 ± 0.1)% for the RGB, (1.6 ± 1.1)% for the AGB, and (0.3 ± 0.1)% for all giants. Because the Li-rich RGB stars are on the lower RGB, Li self-generation mechanisms proposed to occur at the luminosity function bump or He core flash cannot explain these four lower RGB stars. We propose the following origin for Li enrichment: (1) All luminous giants experience a brief phase of Li enrichment at the He core flash. (2) All post-RGB stars with binary companions on the lower RGB will engage in mass transfer. This scenario predicts that 0.1% of lower RGB stars will appear Li-rich due to mass transfer from a recently Li-enhanced companion. This frequency is at the lower end of our confidence interval.

  4. The Gaia-ESO Survey: revisiting the Li-rich giant problem

    Science.gov (United States)

    Casey, A. R.; Ruchti, G.; Masseron, T.; Randich, S.; Gilmore, G.; Lind, K.; Kennedy, G. M.; Koposov, S. E.; Hourihane, A.; Franciosini, E.; Lewis, J. R.; Magrini, L.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Feltzing, S.; Jeffries, R. D.; Vallenari, A.; Bensby, T.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Korn, A. J.; Lanzafame, A.; Pancino, E.; Recio-Blanco, A.; Smiljanic, R.; Carraro, G.; Costado, M. T.; Damiani, F.; Donati, P.; Frasca, A.; Jofré, P.; Lardo, C.; de Laverny, P.; Monaco, L.; Prisinzano, L.; Sbordone, L.; Sousa, S. G.; Tautvaišienė, G.; Zaggia, S.; Zwitter, T.; Delgado Mena, E.; Chorniy, Y.; Martell, S. L.; Silva Aguirre, V.; Miglio, A.; Chiappini, C.; Montalban, J.; Morel, T.; Valentini, M.

    2016-09-01

    The discovery of lithium-rich giants contradicts expectations from canonical stellar evolution. Here we report on the serendipitous discovery of 20 Li-rich giants observed during the Gaia-ESO Survey, which includes the first nine Li-rich giant stars known towards the CoRoT fields. Most of our Li-rich giants have near-solar metallicities and stellar parameters consistent with being before the luminosity bump. This is difficult to reconcile with deep mixing models proposed to explain lithium enrichment, because these models can only operate at later evolutionary stages: at or past the luminosity bump. In an effort to shed light on the Li-rich phenomenon, we highlight recent evidence of the tidal destruction of close-in hot Jupiters at the sub-giant phase. We note that when coupled with models of planet accretion, the observed destruction of hot Jupiters actually predicts the existence of Li-rich giant stars, and suggests that Li-rich stars should be found early on the giant branch and occur more frequently with increasing metallicity. A comprehensive review of all known Li-rich giant stars reveals that this scenario is consistent with the data. However, more evolved or metal-poor stars are less likely to host close-in giant planets, implying that their Li-rich origin requires an alternative explanation, likely related to mixing scenarios rather than external phenomena.

  5. Hydrodynamic Simulations of the Interaction between Giant Stars and Planets

    CERN Document Server

    Staff, Jan E; Wood, Peter; Galaviz, Pablo; Passy, Jean-Claude

    2016-01-01

    We present the results of hydrodynamic simulations of the interaction between a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with a zero-age main sequence mass of 3.5 $M_\\odot$. Dynamic in-spiral timescales are of the order of few years and a few decades for the red and asymptotic giant branch stars, respectively. The planets will eventually be destroyed at a separation from the core of the giants smaller than the resolution of our simulations, either through evaporation or tidal disruption. As the planets in-spiral, the giant stars' envelopes are somewhat puffed up. Based on relatively long timescales and even considering the fact that further in-spiral should take place before the planets are destroyed, we predict that the merger would be difficult to observe, with only a relatively small, slow brightening. Very little mass is unbound in the process. These conclusions may change if the planet's orbit enhances the star's main pulsation modes. Based on the angular momentum transfer,...

  6. Multimodal Distributions along the Horizontal Branch

    CERN Document Server

    Ferraro, F R; Pecci, F F; Dorman, B; Rood, R T; Ferraro, Francesco R.; Paltrinieri, Barbara; Pecci, Flavio Fusi; Dorman, Ben; Rood, Robert T.

    1997-01-01

    We report on HST/WFPC2 U,V and far-ultraviolet observations of two Galactic Globular Clusters (GGCs), NGC 6205 = M13 and NGC 6093 = M80. Both of these clusters have horizontal-branch (HB) tails that extend to the helium-burning main sequence, with the hottest stars reaching theoretical effective temperatures above 35,000 K. In both clusters, groups of stars are found to be separated by narrow gaps along the blue HB sequence. These gaps appear at similar locations in the color-magnitude diagrams of the two clusters. While stochastic effects may give rise to variations in the color distribution along the HB, the coincidence of gaps in different clusters effectively rules this out as the primary cause. The comparison among the clusters strongly suggests that there are separate physical processes operating during the earlier red-giant phase of evolution to produce mass loss.

  7. The abundance spread in the giants of NGC 6752

    Science.gov (United States)

    Norris, J.; Cottrell, P. L.; Freeman, K. C.; Da Costa, G. S.

    1981-02-01

    A spectroscopic survey has been performed of 69 stars on or near the giant branches of the metal-poor globular cluster NGC 6752. Our basic results are: (i) There is a large range in the strength of the violet cyanogen bands on the red giant branch, with the available evidence strongly suggesting that the distribution is bimodal. (ii) The cyanogen variations on the giant branch appear to be accompanied by an anticorrelated variation in the abundance of the CH molecule. Spectrum synthesis analysis of a (CN strong)/(CN weak) pair of stars for which relatively high resolution data are available shows that there is a variation of Δ[N/A] ˜+0.9, and Δ[C/A] ˜-0.3, indicative of the CN cycle. (iii) On the red giant branch there are variations in the strength of the lines of Al I which correlate positively with the cyanogen variations. The size of the variations is consistent with the hypothesis that the same phenomenon has occurred in NGC 6752 and ω Centauri, but to a much smaller extent in the former. (iv) On the asymptotic giant branch (AGB), the features of CH are weaker than on the red giant branch at the same color or magnitude, and there are no examples of stars in the strong CN group. Spectrum synthesis suggests that the behavior of the CH features is consistent, on the average, with the effective temperature and gravities of the AGB stars, but that the absence of strong CN stars cannot be explained in this way. We set an upper limit of Δ[C/H] ˜0.3 to the possible range of carbon on the AGB at log L/L -- stars: individual: ˜2.3, and between this group and stars of similar color on the red giant branch. (v) Most of the stars on the anomalously low luminosity end of the AGB are not members of NGC 6752. Two stars, (CS 41 and CS 44), however, deserve further study, since they could be examples of partially mixed stars. No definitive statement can be made concerning the origin of the abundance anomalies. if mixing is responsible, the data require this process to

  8. Radioiodinated branched carbohydrates

    Science.gov (United States)

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1989-01-01

    A radioiodinated branched carbohydrate for tissue imaging. Iodine-123 is stabilized in the compound by attaching it to a vinyl functional group that is on the carbohydrate. The compound exhibits good uptake and retention and is promising in the development of radiopharmaceuticals for brain, heart and tumor imaging.

  9. Multimode geodesic branching components

    Science.gov (United States)

    Schulz, D.; Voges, E.

    1983-01-01

    Geodesic branching components are investigated for multimode guided wave optics. Geodesic structures with particular properties, e.g. focussing star couplers, are derived by a synthesis technique based on a theorem of Toraldo di Francia. Experimentally, the geodesic surfaces are printed on acrylic glass and are spin-coated with organic film waveguides.

  10. Tracheobronchial Branching Anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Min Ji; Kim, Young Tong; Jou, Sung Shick [Soonchunhyang University, Cheonan Hospital, Cheonan (Korea, Republic of); Park, A Young [Soonchunhyang University College of Medicine, Asan (Korea, Republic of)

    2010-04-15

    There are various congenital anomalies with respect to the number, length, diameter, and location of tracheobronchial branching patterns. The tracheobronchial anomalies are classified into two groups. The first one, anomalies of division, includes tracheal bronchus, cardiac bronchus, tracheal diverticulum, pulmonary isomerism, and minor variations. The second one, dysmorphic lung, includes lung agenesis-hypoplasia complex and lobar agenesis-aplasia complex

  11. Juvenile giant fibroadenoma

    Directory of Open Access Journals (Sweden)

    Vipul Yagnik

    2011-07-01

    Full Text Available Fibroadenomas are benign solid tumor associated with aberration of normal lobular development. Juvenile giant fibroadenoma is usually single and >5 cm in size /or >500 gms in weight. Important differential diagnoses are: phyllodes tumor and juvenile gigantomastia. Simple excision is the treatment of choice.

  12. [Giant retroperitoneal liposarcoma].

    Science.gov (United States)

    Mezzour, Mohamed Hicham; El Messaoudi, Yasser Arafat; Fekak, Hamid; Rabii, Redouane; Marnissi, Farida; Karkouri, Mehdi; Salam, Siham; Iraki, Moulay Ahmed; Joual, Abdenbi; Meziane, Fathi

    2006-02-01

    The authors report a case of giant retroperitoneal liposarcoma. The diagnosis was suspected after scanography and magnetic resonance imaging and confirmed by the histological analysis of the extracted piece after surgical treatment. Postoperative evolution was favourable after one year without recurrence or distant metastasis. The authors discuss the pathologic and therapeutic aspects and the prognosis of retroperitoneal liposarcoma.

  13. Giant Congenital Melanocytic Nevus

    DEFF Research Database (Denmark)

    Rasmussen, Bo Sonnich; Henriksen, Trine Foged; Kølle, Stig-Frederik Trojahn

    2015-01-01

    Giant congenital melanocytic nevi (GCMN) occur in 1:20,000 livebirths and are associated with increased risk of malignant transformation. The treatment of GCMN from 1981 to 2010 in a tertiary referral center was reviewed evaluating the modalities used, cosmetic results, associated complications...

  14. Waking the Sleeping Giant

    NARCIS (Netherlands)

    Ollenburger, Mary H.; Descheemaeker, Katrien; Crane, Todd A.; Sanogo, Ousmane M.; Giller, Ken E.

    2016-01-01

    The World Bank argued that West Africa's Guinea Savannah zone forms part of “Africa's Sleeping Giant,” where increases in agricultural production could be an engine of economic growth, through expansion of cultivated land in sparsely populated areas. The district of Bougouni, in southern Mali,

  15. Critical branching neural networks.

    Science.gov (United States)

    Kello, Christopher T

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical branching and, in doing so, simulates observed scaling laws as pervasive to neural and behavioral activity. These scaling laws are related to neural and cognitive functions, in that critical branching is shown to yield spiking activity with maximal memory and encoding capacities when analyzed using reservoir computing techniques. The model is also shown to account for findings of pervasive 1/f scaling in speech and cued response behaviors that are difficult to explain by isolable causes. Issues and questions raised by the model and its results are discussed from the perspectives of physics, neuroscience, computer and information sciences, and psychological and cognitive sciences.

  16. Generalized Markov branching models

    OpenAIRE

    Li, Junping

    2005-01-01

    In this thesis, we first considered a modified Markov branching process incorporating both state-independent immigration and resurrection. After establishing the criteria for regularity and uniqueness, explicit expressions for the extinction probability and mean extinction time are presented. The criteria for recurrence and ergodicity are also established. In addition, an explicit expression for the equilibrium distribution is presented.\\ud \\ud We then moved on to investigate the basic proper...

  17. Generalized Markov branching models

    OpenAIRE

    Li, Junping

    2005-01-01

    In this thesis, we first considered a modified Markov branching process incorporating both state-independent immigration and resurrection. After establishing the criteria for regularity and uniqueness, explicit expressions for the extinction probability and mean extinction time are presented. The criteria for recurrence and ergodicity are also established. In addition, an explicit expression for the equilibrium distribution is presented. We then moved on to investigate the basic proper...

  18. Tau leptonic branching ratios

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Garrido, L; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    A sample of 62249 \\tau-pair events is selected from data taken with the ALEPH detector in 1991, 1992 and 1993. The measurement of the branching fractions for \\tau decays into electrons and muons is presented with emphasis on the study of systematic effects from selection, particle identification and decay classification. Combined with the most recent ALEPH determination of the \\tau lifetime, these results provide a relative measurement of the leptonic couplings in the weak charged current for transverse W bosons.

  19. Electrochemical Energy Storage Branch

    Science.gov (United States)

    1985-01-01

    The activities of the Electrochemical Energy Storage Branch are highlighted, including the Technology Base Research and the Exploratory Technology Development and Testing projects within the Electrochemical Energy Storage Program for the 1984 fiscal year. General Headquarters activities are presented first; and then, a summary of the Director Controlled Milestones, followed by other major accomplishments. A listing of the workshops and seminars held during the year is also included.

  20. The peculiar Horizontal Branch of NGC 2808

    CERN Document Server

    Dalessandro, E; Ferraro, F R; Cassisi, S; Lanzoni, B; Rood, R T; Pecci, F Fusi; Sabbi, E

    2010-01-01

    We present an accurate analysis of the peculiar Horizontal Branch (HB) of the massive Galactic globular cluster NGC 2808, based on high-resolution far-UV and optical images of the central region of the cluster obtained with HST. We confirm the multimodal distribution of stars along the HB: 4 sub-populations separated by gaps are distinguishable. The detailed comparison with suitable theoretical models showed that (i) it is not possible to reproduce the luminosity of the entire HB with a single helium abundance, while an appropriate modeling is possible for three HB groups by assuming different helium abundances in the range 0.24 < Y < 0.4 that are consistent with the multiple populations observed in the Main Sequence; (ii) canonical HB models are not able to properly match the observational properties of the stars populating the hottest end of the observed HB distribution, the so called "blue-hook region". These objects are probably "hot-flashers" , stars that peel off the red giant branch before reachi...

  1. Giant Cell Arteritis.

    Science.gov (United States)

    Hoffman, Gary S

    2016-11-01

    This issue provides a clinical overview of giant cell arteritis, focusing on diagnosis, treatment, and practice improvement. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of additional science writers and physician writers.

  2. Intraoral giant condyloma acuminatum

    Directory of Open Access Journals (Sweden)

    Gupta R

    2001-09-01

    Full Text Available A case of intraoral giant condyloma acuminatum is reported in a 50- year- old Indian. He did not respond to topical application of podophyllin 20% but responded partially to electric cauterisation. Surgical excision was done to get rid of the warty growh completely. Since there were no skin or genital lesions and no history of marital or extramarital sexual contact the lesion was probably acquired from environmental sources. Nonsexual transmission should be considered especially when the lesions are extragenital.

  3. Giant Otters in Peru

    Directory of Open Access Journals (Sweden)

    Schenk C.

    1992-02-01

    Full Text Available We are in the second year of fieldwork surveying for Giant Otters in the southeastern rainforest of Peru, in three areas with differing levels of legal protection. While there is some illegal hunting still happening outside the protected areas, the main threat to the otters is badly-conducted tourism. Well-organised tourism can be a promising argument for establishing protected areas like national parks.

  4. A giant graviton genealogy

    CERN Document Server

    Lozano, Yolanda; Prinsloo, Andrea

    2013-01-01

    In this article we extend the construction of giant gravitons from holomorphic surfaces [arXiv:hep-th/0010206] to the ABJM correspondence. We construct a new class of 1/6-BPS M5-branes wrapping 5-manifolds in S^7/Z_k and supported by a large angular momentum in the orbifold space. These orbifold giant gravitons undergo a supersymmetry enhancement to 1/3-BPS and 1/2-BPS configurations in special cases. The compactification of M-theory on AdS_4 x S^7/Z_k to type IIA superstring theory on AdS_4 x CP^3 then gives rise to another new class of 1/6-BPS D4 and NS5-branes wrapping 4 and 5-manifolds in CP^3. The D4-branes carry a combination of D0-brane charge and angular momentum in the complex projective space, while the NS5-branes are supported only by D0-brane charge. Finally, we present a detailed analysis of a one-parameter family of 1/2-BPS M5-brane orbifold giant gravitons, and their D4 and NS5-brane CP^3 descendants.

  5. Giant prolactinomas in women

    DEFF Research Database (Denmark)

    Delgrange, Etienne; Raverot, Gerald; Bex, Marie

    2014-01-01

    OBJECTIVE: To characterise distinctive clinical features of giant prolactinomas in women. DESIGN: A multicentre, retrospective case series and literature review. METHODS: We collected data from 15 female patients with a pituitary tumour larger than 4 cm and prolactin levels above 1000 μg/l and id......OBJECTIVE: To characterise distinctive clinical features of giant prolactinomas in women. DESIGN: A multicentre, retrospective case series and literature review. METHODS: We collected data from 15 female patients with a pituitary tumour larger than 4 cm and prolactin levels above 1000 μg....../l and identified 19 similar cases from the literature; a gender-based comparison of the frequency and age distribution was obtained from a literature review. RESULTS: The initial PubMed search using the term 'giant prolactinomas' identified 125 patients (13 women) responding to the inclusion criteria. The female......:male ratio was 1:9. Another six female patients were found by extending the literature search, while our own series added 15 patients. The median age at diagnosis was 44 years in women compared with 35 years in men (Pwomen (n=34), we...

  6. A variable depth search branching

    OpenAIRE

    Cornillier, Fabien; Pécora, José Eduardo; Charles, Vincent

    2017-01-01

    We introduce a variable depth search branching, an extension to the local branching for solving Mixed-Integer Programs. Two strategies are assessed, a best improvement strategy and a first improvement strategy. The extensive computational assessment evidences a significant improvement over the local branching for both strategies. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down.

  7. Combustion Branch Website Development

    Science.gov (United States)

    Bishop, Eric

    2004-01-01

    The NASA combustion branch is a leader in developing and applying combustion science to focused aerospace propulsion systems concepts. It is widely recognized for unique facilities, analytical tools, and personnel. In order to better communicate the outstanding research being done in this Branch to the public and other research organization, a more substantial website was desired. The objective of this project was to build an up-to-date site that reflects current research in a usable and attractive manner. In order to accomplish this, information was requested from all researchers in the Combustion branch, on their professional skills and on the current projects. This information was used to fill in the Personnel and Research sections of the website. A digital camera was used to photograph all personnel and these photographs were included in the personnel section as well. The design of the site was implemented using the latest web standards: xhtml and external css stylesheets. This implementation conforms to the guidelines recommended by the w3c. It also helps to ensure that the web site is accessible by disabled users, and complies with Section 508 Federal legislation (which mandates that all Federal websites be accessible). Graphics for the new site were generated using the gimp (www.gimp.org) an open-source graphics program similar to Adobe Photoshop. Also, all graphics on the site were of a reasonable size (less than 20k, most less than 2k) so that the page would load quickly. Technologies such as Macromedia Flash and Javascript were avoided, as these only function on some clients which have the proper software installed or enabled. The website was tested on different platforms with many different browsers to ensure there were no compatibility issues. The website was tested on windows with MS IE 6, MSIE 5 , Netscape 7, Mozilla and Opera. On a Mac, the site was tested with MS IE 5 , Netscape 7 and Safari.

  8. Giant bullae mimicking tension pneumothorax

    Directory of Open Access Journals (Sweden)

    Ahmet Erbey

    2012-12-01

    Full Text Available Giant bullae may mimic tension pneumothorax radiologicallyso that it may expand completely to hemithorax,increase of radiolucency mediastinal shift, flattening ofdiaphragm and printing on trachea. Sixty one year oldmale patient with giant bullae misdiagnosed as tensionpneumothorax and underwent to tube thoracostomy. Thedifferential diagnosis of giant bullae and tension pneumothoraxmay be confusing. The therapeutic approaches ofthese two radiologically similar entities differ significantly.Thus proper physical assessment and radiological examinationis crucial in the differential diagnosis and computedtomography examination should be performed before theadjustment of therapy. J Clin Exp Invest 2012; 3(4: 548-551Key words: Tension pneumothorax, giant bullae, computedtomography, tube thoracostomy

  9. Branch formation during organ development

    Science.gov (United States)

    Gjorevski, Nikolce; Nelson, Celeste M.

    2010-01-01

    Invertebrates and vertebrates use branching morphogenesis to build epithelial trees to maximize the surface area of organs within a given volume. Several molecular regulators of branching have recently been discovered, a number of which are conserved across different organs and species. Signals that control branching at the cellular and tissue levels are also starting to emerge, and are rapidly unveiling the physical nature of branch development. Here we discuss the molecular, cellular and physical processes that govern branch formation and highlight the major outstanding questions in the field. PMID:20890968

  10. Cookie branching random walks

    CERN Document Server

    Bartsch, Christian; Kochler, Thomas; Müller, Sebastian; Popov, Serguei

    2011-01-01

    We consider a branching random walk on $\\Z$, where the particles behave differently in visited and unvisited sites. Informally, each site on the positive half-line contains initially a cookie. On the first visit of a site its cookie is removed and particles at positions with a cookie reproduce and move differently from particles on sites without cookies. Therefore, the movement and the reproduction of the particles depend on the previous behaviour of the population of particles. We study the question if the process is recurrent or transient, i.e., whether infinitely many particles visit the origin or not.

  11. The branch librarians' handbook

    CERN Document Server

    Rivers, Vickie

    2004-01-01

    ""Recommended""--Booklist; ""an excellent addition...highly recommended""--Public Libraries; ""clear...very sound advice...strongly recommend""--Catholic Library World; ""excellent resource...organized...well written""--Against the Grain; ""interesting...thoroughly practical...a very good book...well organized...clearly written""--ARBA. This handbook covers a wide variety of issues that the branch librarian must deal with every day. Chapters are devoted to mission statements (the Dallas Public Library and Dayton Metro Library mission statements are highlighted as examples), library systems,

  12. Structure and decay properties of spin-dipole giant resonances within a semimicroscopical approach

    NARCIS (Netherlands)

    Moukhai, EA; Rodin, VA; Urin, MH

    1999-01-01

    A semimicroscopical approach is applied to calculate: (i) strength functions for the charge-exchange spin-dipole giant resonances in the Pb-208 parent nucleus; (ii) partial and total branching ratios for the direct proton decay of the resonance in Bi-208. The approach is based on continuum-RPA calcu

  13. Inclusion of Horizontal Branch stars in the derivation of star formation histories of dwarf galaxies: the Carina dSph

    CERN Document Server

    Savino, Alessandro; Tolstoy, Eline

    2015-01-01

    We present a detailed analysis of the Horizontal Branch of the Carina Dwarf Spheroidal Galaxy by means of synthetic modelling techniques, taking consistently into account the star formation history and metallicity evolution as determined from main sequence and red giant branch spectroscopic observations. We found that a range of integrated red giant branch mass loss values of 0.1-0.14 M, increasing with metallicity, is able to reproduce the colour extension of the old Horizontal Branch. However, leaving the mass loss as the only free parameter is not enough to match the detailed morphology of Carina Horizontal Branch. We explored the role played by the star formation history on the discrepancies between synthetic and observed Horizontal Branches. We derived a toy bursty star formation history that reproduces the horizontal branch star counts, and also matches qualitatively the red giant and the turn off regions. This star formation history is made of a subset of age and [M/H] components of the star formation ...

  14. RE-INFLATED WARM JUPITERS AROUND RED GIANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Eric D. [Institute for Astronomy, Royal Observatory Edinburgh, University of Edinburgh, Blackford Hill, Edinburgh (United Kingdom); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2016-02-10

    Since the discovery of the first transiting hot Jupiters, models have sought to explain the anomalously large radii of highly irradiated gas giants. We now know that the size of hot Jupiter radius anomalies scales strongly with a planet's level of irradiation and numerous models like tidal heating, ohmic dissipation, and thermal tides have since been developed to help explain these inflated radii. In general, however, these models can be grouped into two broad categories: models that directly inflate planetary radii by depositing a fraction of the incident irradiation into the interior and models that simply slow a planet's radiative cooling, allowing it to retain more heat from formation and thereby delay contraction. Here we present a new test to distinguish between these two classes of models. Gas giants orbiting at moderate orbital periods around post-main-sequence stars will experience enormous increases to their irradiation as their host stars move up the sub-giant and red-giant branches. If hot Jupiter inflation works by depositing irradiation into the planet's deep interiors then planetary radii should increase in response to the increased irradiation. This means that otherwise non-inflated gas giants at moderate orbital periods of >10 days can re-inflate as their host stars evolve. Here we explore the circumstances that can lead to the creation of these “re-inflated” gas giants and examine how the existence or absence of such planets can be used to place unique constraints on the physics of the hot Jupiter inflation mechanism. Finally, we explore the prospects for detecting this potentially important undiscovered population of planets.

  15. Imaging Extrasolar Giant Planets

    Science.gov (United States)

    Bowler, Brendan P.

    2016-10-01

    High-contrast adaptive optics (AO) imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order AO systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young (≈5-300 Myr) stars spanning stellar masses between 0.1 and 3.0 M ⊙, the overall occurrence rate of 5-13 M Jup companions at orbital distances of 30-300 au is {0.6}-0.5+0.7 % assuming hot-start evolutionary models. The most massive giant planets regularly accessible to direct imaging are about as rare as hot Jupiters are around Sun-like stars. Dividing this sample into individual stellar mass bins does not reveal any statistically significant trend in planet frequency with host mass: giant planets are found around {2.8}-2.3+3.7 % of BA stars, planets spanning a broad range of masses and ages.

  16. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  17. A Giant Urethral Calculus.

    Science.gov (United States)

    Sigdel, G; Agarwal, A; Keshaw, B W

    2014-01-01

    Urethral calculi are rare forms of urolithiasis. Majority of the calculi are migratory from urinary bladder or upper urinary tract. Primary urethral calculi usually occur in presence of urethral stricture or diverticulum. In this article we report a case of a giant posterior urethral calculus measuring 7x3x2 cm in a 47 years old male. Patient presented with acute retention of urine which was preceded by burning micturition and dribbling of urine for one week. The calculus was pushed in to the bladder through the cystoscope and was removed by suprapubic cystolithotomy.

  18. Giant infantile pulmonary hemangioma

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, Rajul; Tummala, Venkat [Hurley Medical Center One Hurley Plaza, Department of Radiology, Flint, MI (United States)

    2010-12-15

    We present a very unusual case of giant infantile pulmonary hemangioma presenting as a large solitary pulmonary mass. This was successfully managed with surgical resection. Histological examination revealed that the mass was positive for GLUT-1 receptor, a marker for infantile hemangioma. To our knowledge only a few cases of pulmonary hemangioma have been described previously in the literature. Pulmonary hemangiomas are very rare lesions, most of them presenting as a pulmonary mass. This case emphasizes the fact that this rare lesion should be considered in the differential of an enhancing pulmonary mass in an infant. (orig.)

  19. Giant Pandas and Their Conservation

    Institute of Scientific and Technical Information of China (English)

    GarethDavey

    2004-01-01

    IT is paradoxical that themost well-known conservation symbol in the world,the giant panda, is a criti-cally endangered species.The estimated 1,600 thatremain live in the high-altitude for-ests of southwest China (within theprovinces of Sichuan, Gansu andShaanxi). Giant pandas are popularand elicit affection and admiration

  20. Famine Threatens the Giant Panda

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Large swathes of arrow bamboo groves at and above 2,700 meters in the Piankou Nature Reserve in Sichuan's Mianyang are producing purple blooms, and some groves have started to wither and die. An absence of bamboo means famine for giant pandas living there. Sichuan has consequently activated its giant panda contingency plan.

  1. Path-valued branching processes and nonlocal branching superprocesses

    CERN Document Server

    Li, Zenghu

    2012-01-01

    A family of continuous-state branching processes with immigration are constructed as the solution flow of a stochastic equation system driven by time-space noises. The family can be regarded as an inhomogeneous increasing path-valued branching process with immigration. Two nonlocal branching immigration superprocesses can be defined from the flow. We identify explicitly the branching and immigration mechanisms of those processes. The results provide new perspectives into the tree-valued Markov processes of Aldous and Pitman [Ann. Inst. H. Poincare Probab. Statist. 34 (1998), 637--686] and Abraham and Delmas [Ann. Probab. To appear].

  2. Re-inflated Warm Jupiters Around Red Giants

    CERN Document Server

    Lopez, Eric D

    2015-01-01

    Since the discovery of the first transiting hot Jupiters, models have sought to explain the anomalously large radii of highly irradiated gas giants. We now know that the size of hot Jupiter radius anomalies scales strongly with a planet's level of irradiation and numerous models like tidal heating, ohmic dissipation, and thermal tides have since been developed to help explain these inflated radii. In general however, these models can be grouped into two broad categories: 1) models that directly inflate planetary radii by depositing a fraction of the incident irradiation into the interior and 2) models that simply slow a planet's radiative cooling allowing it to retain more heat from formation and thereby delay contraction. Here we present a new test to distinguish between these two classes of models. Gas giants orbiting at moderate orbital periods around post main sequence stars will experience enormous increases their irradiation as their host stars move up the sub-giant and red-giant branches. If hot Jupite...

  3. Quiver Varieties and Branching

    Directory of Open Access Journals (Sweden)

    Hiraku Nakajima

    2009-01-01

    Full Text Available Braverman and Finkelberg recently proposed the geometric Satake correspondence for the affine Kac-Moody group Gaff [Braverman A., Finkelberg M., arXiv:0711.2083]. They conjecture that intersection cohomology sheaves on the Uhlenbeck compactification of the framed moduli space of Gcpt-instantons on $R^4/Z_r$ correspond to weight spaces of representations of the Langlands dual group $G_{aff}^{vee}$ at level $r$. When $G = SL(l$, the Uhlenbeck compactification is the quiver variety of type $sl(r_{aff}$, and their conjecture follows from the author's earlier result and I. Frenkel's level-rank duality. They further introduce a convolution diagram which conjecturally gives the tensor product multiplicity [Braverman A., Finkelberg M., Private communication, 2008]. In this paper, we develop the theory for the branching in quiver varieties and check this conjecture for $G = SL(l$.

  4. Integrating over Higgs branches

    Energy Technology Data Exchange (ETDEWEB)

    Moore, G. [Yale Univ., New Haven, CT (United States). Dept. of Physics; Nekrasov, N. [Institute of Theoretical and Experimental Physics, 117259, Moscow (Russian Federation); Shatashvili, S. [Lyman Laboratory of Physics, Harvard University, Cambridge, MA (United States)

    2000-01-01

    We develop some useful techniques for integrating over Higgs branches in supersymmetric theories with 4 and 8 supercharges. In particular, we define a regularized volume for hyperkaehler quotients. We evaluate this volume for certain ALE and ALF spaces in terms of the hyperkaehler periods. We also reduce these volumes for a large class of hyperkaehler quotients to simpler integrals. These quotients include complex coadjoint orbits, instanton moduli spaces on R{sup 4} and ALE manifolds, Hitchin spaces, and moduli spaces of (parabolic) Higgs bundles on Riemann surfaces. In the case of Hitchin spaces the evaluation of the volume reduces to a summation over solutions of Bethe ansatz equations for the non-linear Schroedinger system. We discuss some applications of our results. (orig.)

  5. Axon Termination, Pruning, and Synaptogenesis in the Giant Fiber System of Drosophila melanogaster Is Promoted by Highwire.

    Science.gov (United States)

    Borgen, Melissa; Rowland, Kimberly; Boerner, Jana; Lloyd, Brandon; Khan, Aruna; Murphey, Rodney

    2017-03-01

    The ubiquitin ligase Highwire has a conserved role in synapse formation. Here, we show that Highwire coordinates several facets of central synapse formation in the Drosophila melanogaster giant fiber system, including axon termination, axon pruning, and synaptic function. Despite the similarities to the fly neuromuscular junction, the role of Highwire and the underlying signaling pathways are distinct in the fly's giant fiber system. During development, branching of the giant fiber presynaptic terminal occurs and, normally, the transient branches are pruned away. However, in highwire mutants these ectopic branches persist, indicating that Highwire promotes axon pruning. highwire mutants also exhibit defects in synaptic function. Highwire promotes axon pruning and synaptic function cell-autonomously by attenuating a mitogen-activated protein kinase pathway including Wallenda, c-Jun N-terminal kinase/Basket, and the transcription factor Jun. We also show a novel role for Highwire in non-cell autonomous promotion of synaptic function from the midline glia. Highwire also regulates axon termination in the giant fibers, as highwire mutant axons exhibit severe overgrowth beyond the pruning defect. This excessive axon growth is increased by manipulating Fos expression in the cells surrounding the giant fiber terminal, suggesting that Fos regulates a trans-synaptic signal that promotes giant fiber axon growth. Copyright © 2017 by the Genetics Society of America.

  6. Giant Intradiverticular Bladder Tumor

    Science.gov (United States)

    Noh, Mohamad Syafeeq Faeez Md; Aziz, Ahmad Fuad Abdul; Ghani, Khairul Asri Mohd; Siang, Christopher Lee Kheng; Yunus, Rosna; Yusof, Mubarak Mohd

    2017-01-01

    Patient: Male, 74 Final Diagnosis: Giant intradiverticular bladder tumor with metastasis Symptoms: Hematuria Medication:— Clinical Procedure: — Specialty: Urology Objective: Rare disease Background: Intradiverticular bladder tumors are rare. This renders diagnosis of an intradiverticular bladder tumor difficult. Imaging plays a vital role in achieving the diagnosis, and subsequently staging of the disease. Case Report: A 74-year-old male presented to our center with a few months history of constitutional symptoms. Upon further history, he reported hematuria two months prior to presentation, which stopped temporarily, only to recur a few days prior to coming to the hospital. The patient admitted to having lower urinary tract symptoms. However, there was no dysuria, no sandy urine, and no fever. Palpation of his abdomen revealed a vague mass at the suprapubic region, which was non tender. In view of his history and the clinical examination findings, an ultrasound of the abdomen and computed tomography (CT) was arranged. These investigations revealed a giant tumor that seemed to be arising from a bladder diverticulum, with a mass effect and hydronephrosis. He later underwent operative intervention. Conclusions: Intradiverticular bladder tumors may present a challenge to the treating physician in an atypical presentation; thus requiring a high index of suspicion and knowledge of tumor pathophysiology. As illustrated in our case, CT with its wide availability and multiplanar imaging capabilities offers a useful means for diagnosis, disease staging, operative planning, and follow-up. PMID:28246375

  7. Rapidly Evolving Giant Dermatofibroma

    Directory of Open Access Journals (Sweden)

    K. J. Lang

    2010-01-01

    Full Text Available Dermatofibroma, also known as “fibrous histiocytoma”, is a benign dermal or subcutaneous poorly circumscribed proliferation of spindle-shaped fibroblasts and macrophages in the dermis. Although it is commonly present as a brownish nodule the legs of females, it may also arise on the upper extremities, trunk, and rarely on the head. The exact pathogenesis is unclear. However, it is widely believed that the originating insult to the dermis is a folliculitis, an arthropod bite, or an unspecified initial inflammatory condition. Giant dermatofibromas of greater than 5 cm in diameter are rare, with only 22 cases reported in the literature. We present a case of a rapidly evolving pedunculated mass in the groin of a male patient. Histological examination confirmed this to be a giant dermatofibroma. Though this specimen cannot is not confirmed as such, the cellular subtype is sometimes present as a larger lesion with anecdotal reports of local recurrence and distant metastases. The clinical and radiological features which were somewhat suspicious of malignancy are considered in the context of the definitive pathological diagnosis of a benign lesion.

  8. Reinflating Giant Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    Two new, large gas-giant exoplanets have been discovered orbiting close to their host stars. A recent study examining these planets and others like them may help us to better understand what happens to close-in hot Jupiters as their host stars reach the end of their main-sequence lives.OversizedGiantsUnbinned transit light curves for HAT-P-65b. [Adapted from Hartman et al. 2016]The discovery of HAT-P-65b and HAT-P-66b, two new transiting hot Jupiters, is intriguing. These planets have periods of just under 3 days and masses of roughly 0.5 and 0.8 times that of Jupiter, but their sizes are whats really interesting: they have inflated radii of 1.89 and 1.59 times that of Jupiter.These two planets, discovered using the Hungarian-made Automated Telescope Network (HATNet) in Arizona and Hawaii, mark the latest in an ever-growing sample of gas-giant exoplanets with radii larger than expected based on theoretical planetary structure models.What causes this discrepancy? Did the planets just fail to contract to the expected size when they were initially formed, or were they reinflated later in their lifetimes? If the latter, how? These are questions that scientists are only now starting to be able to address using statistics of the sample of close-in, transiting planets.Unbinned transit light curves for HAT-P-66b. [Hartman et al. 2016]Exploring Other PlanetsLed by Joel Hartman (Princeton University), the team that discovered HAT-P-65b and HAT-P-66b has examined these planets observed parameters and those of dozens of other known close-in, transiting exoplanets discovered with a variety of transiting exoplanet missions: HAT, WASP, Kepler, TrES, and KELT. Hartman and collaborators used this sample to draw conclusions about what causes some of these planets to have such large radii.The team found that there is a statistically significant correlation between the radii of close-in giant planets and the fractional ages of their host stars (i.e., the stars age divided by its full

  9. Carbon in Red Giants in Globular Clusters and Dwarf Spheroidal Galaxies

    CERN Document Server

    Kirby, Evan N; Zhang, Andrew J; Deng, Michelle; Cohen, Judith G; Guhathakurta, Puragra; Shetrone, Matthew D; Lee, Young Sun; Rizzi, Luca

    2015-01-01

    We present carbon abundances of red giants in Milky Way globular clusters and dwarf spheroidal galaxies (dSphs). Our sample includes measurements of carbon abundances for 154 giants in the clusters NGC 2419, M68, and M15 and 398 giants in the dSphs Sculptor, Fornax, Ursa Minor, and Draco. This sample doubles the number of dSph stars with measurements of [C/Fe]. The [C/Fe] ratio in the clusters decreases with increasing luminosity above log(L/L_sun) ~= 1.6, which can be explained by deep mixing in evolved giants. The same decrease is observed in dSphs, but the initial [C/Fe] of the dSph giants is not uniform. Stars in dSphs at lower metallicities have larger [C/Fe] ratios. We hypothesize that [C/Fe] (corrected to the initial carbon abundance) declines with increasing [Fe/H] due to the metallicity dependence of the carbon yield of asymptotic giant branch stars and due to the increasing importance of Type Ia supernovae at higher metallicities. We also identified 11 very carbon-rich giants (8 previously known) in...

  10. Discovery of Super-Li Rich Red Giants in Dwarf Spheroidal Galaxies

    CERN Document Server

    Kirby, Evan; Guhathakurta, Puragra; Deng, Licai

    2012-01-01

    Stars destroy lithium (Li) in their normal evolution. The convective envelopes of evolved red giants reach temperatures of millions of K, hot enough for the 7Li(p,alpha)4He reaction to burn Li efficiently. Only about 1% of first-ascent red giants more luminous than the luminosity function bump in the red giant branch exhibit A(Li) > 1.5. Nonetheless, Li-rich red giants do exist. We present 15 Li-rich red giants--14 of which are new discoveries--among a sample of 2054 red giants in Milky Way dwarf satellite galaxies. Our sample more than doubles the number of low-mass, metal-poor ([Fe/H] <~ -0.7) Li-rich red giants, and it includes the most-metal poor Li-enhanced star known ([Fe/H] = -2.82, A(Li)_NLTE = 3.15). Because most of these stars have Li abundances larger than the universe's primordial value, the Li in these stars must have been created rather than saved from destruction. These Li-rich stars appear like other stars in the same galaxies in every measurable regard other than Li abundance. We consider ...

  11. Methods and Technologies Branch (MTB)

    Science.gov (United States)

    The Methods and Technologies Branch focuses on methods to address epidemiologic data collection, study design and analysis, and to modify technological approaches to better understand cancer susceptibility.

  12. HST Observations of New Horizontal Branch Structures in the Globular Cluster omega Centauri

    CERN Document Server

    Da Cruz, N L; Rood, R T; Whitney, J H; Dorman, B; Landsman, W B; Hill, R S; Stecher, T P; Bohlin, R C; Cruz, Noella L. D'; Connell, Robert W. O'; Rood, Robert T.; Whitney, Jonathan H.; Dorman, Ben; Landsman, Wayne B.; Hill, Robert S.; Stecher, Theodore P.; Bohlin, Ralph C.

    1999-01-01

    The globular cluster omega Centauri contains the largest known population of very hot horizontal branch (HB) stars. We have used the Hubble Space Telescope to obtain a far-UV/optical color-magnitude diagram of three fields in omega Cen. We find that over 30% of the HB objects are ``extreme'' HB or hot post-HB stars. The hot HB stars are not concentrated toward the cluster center, which argues against a dynamical origin for them. A wide gap in the color distribution of the hot HB stars appears to correspond to gaps found earlier in several other clusters. This suggests a common mechanism, probably related to giant branch mass loss. The diagram contains a significant population of hot sub-HB stars, which we interpret as the ``blue-hook'' objects predicted by D'Cruz et al. (1996a). These are produced by late He-flashes in stars which have undergone unusually large giant branch mass loss. omega Cen has a well-known spread of metal abundance, and our observations are consistent with a giant branch mass loss effici...

  13. Hydrodynamic simulations of the interaction between giant stars and planets

    Science.gov (United States)

    Staff, Jan E.; De Marco, Orsola; Wood, Peter; Galaviz, Pablo; Passy, Jean-Claude

    2016-05-01

    We present the results of hydrodynamic simulations of the interaction between a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with a zero-age main sequence mass of 3.5 M⊙. Dynamic in-spiral time-scales are of the order of few years and a few decades for the red and asymptotic giant branch stars, respectively. The planets will eventually be destroyed at a separation from the core of the giants smaller than the resolution of our simulations, either through evaporation or tidal disruption. As the planets in-spiral, the giant stars' envelopes are somewhat puffed up. Based on relatively long time-scales and even considering the fact that further in-spiral should take place before the planets are destroyed, we predict that the merger would be difficult to observe, with only a relatively small, slow brightening. Very little mass is unbound in the process. These conclusions may change if the planet's orbit enhances the star's main pulsation modes. Based on the angular momentum transfer, we also suspect that this star-planet interaction may be unable to lead to large-scale outflows via the rotation-mediated dynamo effect of Nordhaus and Blackman. Detectable pollution from the destroyed planets would only result for the lightest, lowest metallicity stars. We furthermore find that in both simulations the planets move through the outer stellar envelopes at Mach-3 to Mach-5, reaching Mach-1 towards the end of the simulations. The gravitational drag force decreases and the in-spiral slows down at the sonic transition, as predicted analytically.

  14. Pygmies, Giants, and Skins

    CERN Document Server

    Piekarewicz, J

    2012-01-01

    Understanding the equation of state (EOS) of neutron-rich matter is a central goal of nuclear physics that cuts across a variety of disciplines. Indeed, the limits of nuclear existence, the collision of energetic heavy ions, the structure of neutron stars, and the dynamics of core-collapse supernova all depend critically on the nuclear-matter EOS. In this contribution I focus on the EOS of cold baryonic matter with special emphasis on its impact on the structure, dynamics, and composition of neutron stars. In particular, I discuss how laboratory experiments on neutron skins as well as on Pygmy and Giant resonances can help us elucidate the structure of these fascinating objects.

  15. [Giant esophageal fibrovascular polyp].

    Science.gov (United States)

    Palacios, Fernando; Contardo, Carlos; Guevara, Jorge; Vera, Augusto; Aguilar, Luis; Huamán, Manuel; Palomino, Américo; Yabar, Alejandro

    2003-01-01

    Fibrovascular polyps are extremely rare benign neoplasias of the esophagus, which usually originate in the lower cricoid area. They do not produce any discomfort in the patient for a long time, however it may make itself evident by the patient's regurgitation of the polyp, producing asphyxia or, more frequently, dysphagia. The case of a 58 year old male patient is presented herein, with a 9 month record of dysphagia, weight loss and intermittent melena. The barium x-ray showed a distended esophagus, with a tumor running from the upper esophageal sphincter to the cardia. The endoscopy confirmed the presence of a pediculated tumor, implanted in the cervical esophagus. Surgeons suspected the potential malignancy of the tumor and performed a transhiatal esophagectomy. The final pathologic diagnosis was giant fibrovascular esophageal polyp.

  16. Tau hadronic branching ratios

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    From 64492 selected \\tau-pair events, produced at the Z^0 resonance, the measurement of the tau decays into hadrons from a global analysis using 1991, 1992 and 1993 ALEPH data is presented. Special emphasis is given to the reconstruction of photons and \\pi^0's, and the removal of fake photons. A detailed study of the systematics entering the \\pi^0 reconstruction is also given. A complete and consistent set of tau hadronic branching ratios is presented for 18 exclusive modes. Most measurements are more precise than the present world average. The new level of precision reached allows a stringent test of \\tau-\\mu universality in hadronic decays, g_\\tau/g_\\mu \\ = \\ 1.0013 \\ \\pm \\ 0.0095, and the first measurement of the vector and axial-vector contributions to the non-strange hadronic \\tau decay width: R_{\\tau ,V} \\ = \\ 1.788 \\ \\pm \\ 0.025 and R_{\\tau ,A} \\ = \\ 1.694 \\ \\pm \\ 0.027. The ratio (R_{\\tau ,V} - R_{\\tau ,A}) / (R_{\\tau ,V} + R_{\\tau ,A}), equal to (2.7 \\pm 1.3) \\ \\%, is a measure of the importance of Q...

  17. A giant Ordovician anomalocaridid.

    Science.gov (United States)

    Van Roy, Peter; Briggs, Derek E G

    2011-05-26

    Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542-501 million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups--but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marjum Formation of Utah but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488-472 million years ago) Fezouata Biota in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30 million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills.

  18. The Giant Magnetocaloric Effect

    Science.gov (United States)

    Pecharsky, Vitalij K.

    1998-03-01

    Since the discovery of the magnetocaloric effect in pure iron by E.Warburg in 1881, it has been measured experimentally on many magnetic metals and compounds. The majority of the materials studied order magnetically undergoing a second order phase transformation. The magnetocaloric effect, typically peaking near the Curie or the Néel temperature, generally ranges from 0.5 to 2 K (in terms of adiabatic temperature change) or at 1 to 4 J/kg K (in terms of isothermal magnetic entropy change) per 1 T magnetic field change. The giant magnetocaloric effect recently discovered in Gd_5(Si_xGe_1-x)4 alloys, where x refrigerant capacity, which is the measure of how much heat can be transferred from a cold to a hot reservoir in one ideal thermodynamic cycle, is larger than that of the best second order phase transition materials by 25 to 100%. When the Gd_5(Si_xGe_1-x)4 alloys are compared with other known materials, which show first order magnetic phase transition, such as Dy, Ho, Er, HoCo_2, NdMn_2Si_2, Fe_0.49Rh_0.51, and (Hf_0.83Ta_0.17)Fe_2+x, only Fe_0.49Rh_0.51 has comparable magnetocaloric properties. However, the first order magnetic phase transition in Fe_0.49Rh_0.51 is irreversible, and the magnetocaloric effect disappears after one magnetizing/demagnetizing cycle. A study of the crystal structure, thermodynamics, and magnetism of the Gd_5(Si_xGe_1-x)4 alloys, where 0 basic relations between the composition, the crystal structure, and the change in thermodynamics and magnetocaloric properties, which occur in the Gd_5(Si_xGe_1-x)4 system, and which brings about the giant magnetocaloric effect when x <= 0.5.

  19. A sequence of nitrogen-rich very red giants in the globular cluster NGC 1851

    CERN Document Server

    Carretta, Eugenio; Gratton, Raffaele G; Lucatello, Sara

    2014-01-01

    We present the abundances of N in a sample of 62 stars on the red giant branch (RGB) in the peculiar globular cluster NGC 1851. The values of [N/Fe] ratio were obtained by comparing the flux measured in the observed spectra with that from synthetic spectra for up to about 15 features of CN. This is the first time that N abundances are obtained for such a large sample of RGB stars from medium-resolution spectroscopy in this cluster. With these abundances we provide a chemical tagging of the split red giant branch found from several studies in NGC 1851. The secondary, reddest sequence on the RGB is populated almost exclusively by N-rich stars, confirming our previous suggestion based on Stromgren magnitudes and colours. These giants are also, on average, enriched in s-process elements such as Ba, and are likely the results of pollution from low mass stars that experienced episodes of third dredge-up in the asymptotic giant branch phase.

  20. Landscape of the lost giants

    Science.gov (United States)

    2013-09-01

    The Pleistocene megafauna extinction erased a group of remarkable animals. Whether humans had a prominent role in the extinction remains controversial, but it is emerging that the disappearance of the giants has markedly affected the environment.

  1. Atmospheres of Extrasolar Giant Planets

    CERN Document Server

    Marley, M S; Seager, S; Barman, T; Marley, Mark S.; Fortney, Jonathan; Seager, Sara; Barman, Travis

    2006-01-01

    The key to understanding an extrasolar giant planet's spectrum--and hence its detectability and evolution--lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets are in hand, atmosphere models can be used to constrain atmospheric composition, thermal structure, and ultimately the formation and evolution of detected planets. We review the important physical processes that influence the atmospheric structure and evolution of extrasolar giant planets and consider what has already been learned from the first generation of observations and modeling. We pay particular attention to the roles of cloud structure, metallicity, and atmospheric chemistry in affecting detectable properties through Spitzer Space Telescope observations of the transiting giant planets. Our review stresses the uncertainties that ultimately limit our ability to interpret EGP observations. Finally we will conclude with a look to the future as characterization of multiple individual planets in a ...

  2. Atmospheres of Extrasolar Giant Planets

    Science.gov (United States)

    Marley, Mark

    2006-01-01

    The next decade will almost certainly see the direct imaging of extrasolar giant planets around nearby stars. Unlike purely radial velocity detections, direct imaging will open the door to characterizing the atmosphere and interiors of extrasola planets and ultimately provide clues on their formation and evolution through time. This process has already begun for the transiting planets, placing new constraints on their atmospheric structure, composition, and evolution. Indeed the key to understanding giant planet detectability, interpreting spectra, and constraining effective temperature and hence evolution-is the atmosphere. I will review the universe of extrasolar giant planet models, focusing on what we have already learned from modeling and what we will likely be able to learn from the first generation of direct detection data. In addition to these theoretical considerations, I will review the observations and interpretation of the - transiting hot Jupiters. These objects provide a test of our ability to model exotic atmospheres and challenge our current understanding of giant planet evolution.

  3. Hierarchical spin-orbital polarization of a giant Rashba system.

    Science.gov (United States)

    Bawden, Lewis; Riley, Jonathan M; Kim, Choong H; Sankar, Raman; Monkman, Eric J; Shai, Daniel E; Wei, Haofei I; Lochocki, Edward B; Wells, Justin W; Meevasana, Worawat; Kim, Timur K; Hoesch, Moritz; Ohtsubo, Yoshiyuki; Le Fèvre, Patrick; Fennie, Craig J; Shen, Kyle M; Chou, Fangcheng; King, Phil D C

    2015-09-01

    The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

  4. Annular Elastolytic Giant Cell Granuloma

    Directory of Open Access Journals (Sweden)

    Khandpur Sujay

    2001-01-01

    Full Text Available The clinical and histopathological features of annular elastolytic giant cell granuloma in a 42â€"year-old female patient are described. The condition presented as annular erythematous plaques over sun- exposed skin sparing the face. Histopathology revealed dense granulomatous infiltrate consisting of numerous giant cells and lymphohistiocytes without any palisading arrangement or necrobiosis. The features differentiating it from other similar granulomatous disorders are discussed.

  5. Scaling Behaviors of Branched Polymers

    CERN Document Server

    Aoki, H; Kawai, H; Kitazawa, Y; Aoki, Hajime; Iso, Satoshi; Kawai, Hikaru; Kitazawa, Yoshihisa

    2000-01-01

    We study the thermodynamic behavior of branched polymers. We first study random walks in order to clarify the thermodynamic relation between the canonical ensemble and the grand canonical ensemble. We then show that correlation functions for branched polymers are given by those for $\\phi^3$ theory with a single mass insertion, not those for the $\\phi^3$ theory themselves. In particular, the two-point function behaves as $1/p^4$, not as $1/p^2$, in the scaling region. This behavior is consistent with the fact that the Hausdorff dimension of the branched polymer is four.

  6. Continuous-state branching processes

    CERN Document Server

    Li, Zenghu

    2012-01-01

    These notes were used in a short graduate course on branching processes the author gave in Beijing Normal University. The following main topics are covered: scaling limits of Galton--Watson processes, continuous-state branching processes, extinction probabilities, conditional limit theorems, decompositions of sample paths, martingale problems, stochastic equations, Lamperti's transformations, independent and dependent immigration processes. Some of the results are simplified versions of those in the author's book "Measure-valued branching Markov processes" (Springer, 2011). We hope these simplified results will set out the main ideas in an easy way and lead the reader to a quick access of the subject.

  7. Branch facial nerve trauma after superficial temporal artery biopsy: a case report

    Directory of Open Access Journals (Sweden)

    Rison Richard A

    2011-01-01

    Full Text Available Abstract Introduction Giant cell arteritis is an emergency requiring prompt diagnosis and treatment. Superficial temporal artery biopsy is the gold diagnostic standard. Complications are few and infrequent; however, facial nerve injury has been reported, leaving an untoward cosmetic outcome. This case report is to the best of our knowledge only the fourth one presented in the available literature so far regarding facial nerve injury from superficial temporal artery biopsy. Case presentation A 73-year-old Caucasian woman presented for neurological evaluation regarding eyebrow and facial asymmetry after a superficial temporal artery biopsy for presumptive giant cell arteritis-induced cephalalgia. Conclusion Damage to branches of the facial nerve may occur after superficial temporal artery biopsy, resulting in eyebrow droop. Although an uncommon and sparsely reported complication, all clinicians of various specialties involved in the care of these patients should be aware of this given the gravity of giant cell arteritis and the widespread use of temporal artery biopsy.

  8. Bringing Low the Giants

    CERN Multimedia

    2001-01-01

    Their work goes on unseen, because they a hundred metres beneath your feet. But while the race against the clock to build the LHC has begun on the surface, teams underground are feverishly engaged to dismantle LEP and its experiments. Four months after the start of dismantling, the technical coordinators of the different experiments discuss the progress of work. Little men attack the giant ALEPH. The barrel and its two endcaps have been removed to the end of the cavern and stripped of their cables. The breaking up of the detector can now begin. At ALEPH, counting rooms removed all in one go Jean-Paul Fabre, technical coordinator at ALEPH:'After making safe the structure, the first step was to remove the wiring and cables. Some 210 cubic metres were brought out. Then the counting rooms all round the detector were taken out. They were brought up from the cavern all in one go, up through the shaft, which is 10 metres wide and 150 metres deep. They made it with 15 centimetres to spare. They have been emptied of...

  9. Giant high occipital encephalocele

    Directory of Open Access Journals (Sweden)

    Agrawal Amit

    2016-03-01

    Full Text Available Encephaloceles are rare embryological mesenchymal developmental anomalies resulting from inappropriate ossification in skull through with herniation of intracranial contents of the sac. Encephaloceles are classified based on location of the osseous defect and contents of sac. Convexity encephalocele with osseous defect in occipital bone is called occipital encephalocele. Giant occipital encephaloceles can be sometimes larger than the size of baby skull itself and they pose a great surgical challenge. Occipital encephaloceles (OE are further classified as high OE when defect is only in occipital bone above the foramen magnum, low OE when involving occipital bone and foramen magnum and occipito-cervical when there involvement of occipital bone, foramen magnum and posterior upper neural arches. Chiari III malformation can be associated with high or low occipital encephaloceles. Pre-operatively, it is essential to know the size of the sac, contents of the sac, relation to the adjacent structures, presence or absence of venous sinuses/vascular structures and osseous defect size. Sometimes it becomes imperative to perform both CT and MRI for the necessary information. Volume rendered CT images can depict the relation of osseous defect to foramen magnum and provide information about upper neural arches which is necessary in classifying these lesions.

  10. Giant cell arteritis.

    Science.gov (United States)

    Ninan, Jem; Lester, Susan; Hill, Catherine

    2016-02-01

    Giant cell arteritis (GCA) is the most common vasculitis of the elderly. The diagnosis can be challenging at times because of the limitation of the American Rheumatology Association (ARA) classification criteria and the significant proportion of biopsy-negative patients with GCA. We discuss the role of advanced imaging techniques, including positron emission tomography (PET) scanning, in establishing diagnosis and improved histopathology techniques to improve the sensitivity of temporal artery biopsy. There have been significant advances in the understanding of the pathogenesis of GCA, particularly the role of cytokine pathways such as the interleukins, IL-6-IL-17 axis, and the IL-12-interferon-γ axis and their implication for new therapies. We highlight that glucocorticoids remain the primary treatment for GCA, but recognize the risk of steroid-induced side effects. A number of pharmacotherapies to enable glucocorticoid dose reduction and prevent relapse have been studied. Early diagnosis and fast-track pathways have improved outcomes by encouraging adherence to evidence-based practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Imaging Extrasolar Giant Planets

    CERN Document Server

    Bowler, Brendan P

    2016-01-01

    High-contrast adaptive optics imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order adaptive optics systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young ($\\approx$5--300~Myr) stars spanning stellar masses between 0.1--3.0~\\Msun, the overall occurrence rate of 5--13~\\Mjup \\ companions at orbital distances ...

  12. Giant viruses, giant chimeras: The multiple evolutionary histories of Mimivirus genes

    Directory of Open Access Journals (Sweden)

    Brochier-Armanet Céline

    2008-01-01

    Full Text Available Abstract Background Although capable to evolve, viruses are generally considered non-living entities because they are acellular and devoid of metabolism. However, the recent publication of the genome sequence of the Mimivirus, a giant virus that parasitises amoebas, strengthened the idea that viruses should be included in the tree of life. In fact, the first phylogenetic analyses of a few Mimivirus genes that are also present in cellular lineages suggested that it could define an independent branch in the tree of life in addition to the three domains, Bacteria, Archaea and Eucarya. Results We tested this hypothesis by carrying out detailed phylogenetic analyses for all the conserved Mimivirus genes that have homologues in cellular organisms. We found no evidence supporting Mimivirus as a new branch in the tree of life. On the contrary, our phylogenetic trees strongly suggest that Mimivirus acquired most of these genes by horizontal gene transfer (HGT either from its amoebal hosts or from bacteria that parasitise the same hosts. The detection of HGT events involving different eukaryotic donors suggests that the spectrum of hosts of Mimivirus may be larger than currently known. Conclusion The large number of genes acquired by Mimivirus from eukaryotic and bacterial sources suggests that HGT has been an important process in the evolution of its genome and the adaptation to parasitism.

  13. Left bundle-branch block

    DEFF Research Database (Denmark)

    Risum, Niels; Strauss, David; Sogaard, Peter

    2013-01-01

    The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...

  14. Left bundle-branch block

    DEFF Research Database (Denmark)

    Risum, Niels; Strauss, David; Sogaard, Peter;

    2013-01-01

    The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...

  15. Novel side branch ostial stent.

    Science.gov (United States)

    Chen, Shao-Liang; Lv, Shu-Zheng; Kwan, Tak W

    2009-04-01

    Bifurcation lesions are technically challenging and plagued by a high incidence of restenosis, especially at the side branch orifice, which results in a more frequent need for revascularization during the follow-up period. This report discusses two clinical experiences with a novel side branch ostial stent, the BIGUARD stent, designed for the treatment of bifurcation lesions; procedural success with no in-hospital complications was observed in types IVb and Ia lesions.

  16. The Super Lithium-Rich Red Giant Rapid Rotator G0928+73.2600: A Case for Planet Accretion?

    CERN Document Server

    Carlberg, Joleen K; Cunha, Katia; Majewski, Steven R; Rood, Robert T; 10.1088/2041-8205/723/1/L103

    2010-01-01

    We present the discovery of a super lithium-rich K giant star, G0928+73.2600. This red giant (T_eff = 4885 K and log g = 2.65) is a fast rotator with a projected rotational velocity of 8.4 km/s and an unusually high lithium abundance of A(Li) = 3.30 dex. Although the lack of a measured parallax precludes knowing the exact evolutionary phase, an isochrone-derived estimate of its luminosity places the star on the Hertzsprung-Russell diagram in a location that is not consistent with either the red bump on the first ascent of the red giant branch or with the second ascent on the asymptotic giant branch, the two evolutionary stages where lithium-rich giant stars tend to cluster. Thus, even among the already unusual group of lithium-rich giant stars, G0928+73.2600 is peculiar. Using 12C/13C as a tracer for mixing---more mixing leads to lower 12C/13C---we find 12C/13C = 28, which is near the expected value for standard first dredge-up mixing. We can therefore conclude that "extra" deep mixing has not occurred. Regar...

  17. Structural Mechanics and Dynamics Branch

    Science.gov (United States)

    Stefko, George

    2003-01-01

    The 2002 annual report of the Structural Mechanics and Dynamics Branch reflects the majority of the work performed by the branch staff during the 2002 calendar year. Its purpose is to give a brief review of the branch s technical accomplishments. The Structural Mechanics and Dynamics Branch develops innovative computational tools, benchmark experimental data, and solutions to long-term barrier problems in the areas of propulsion aeroelasticity, active and passive damping, engine vibration control, rotor dynamics, magnetic suspension, structural mechanics, probabilistics, smart structures, engine system dynamics, and engine containment. Furthermore, the branch is developing a compact, nonpolluting, bearingless electric machine with electric power supplied by fuel cells for future "more electric" aircraft. An ultra-high-power-density machine that can generate projected power densities of 50 hp/lb or more, in comparison to conventional electric machines, which generate usually 0.2 hp/lb, is under development for application to electric drives for propulsive fans or propellers. In the future, propulsion and power systems will need to be lighter, to operate at higher temperatures, and to be more reliable in order to achieve higher performance and economic viability. The Structural Mechanics and Dynamics Branch is working to achieve these complex, challenging goals.

  18. Radiation effects on branched polysilanes

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, K.; Seki, S.; Tagawa, S. [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Shibata, H.; Iwai, T. [Tokyo Univ. (Japan). Research Center for Nuclear Science and Technology

    2000-03-01

    We observed crosslinking and scission caused by gamma radiation in linear and branched polysilanes which have from 5% to 33% of the branching points. The crosslinking reactions become predominant for the irradiation with branching density increasing. The cleavage did not take place exclusively at the branching points and branching polysilanes are sensitive to radiation extraordinary as compared with linear polysilane from a careful study of the radiolysis products of a series of polysilanes. This is due to the increasing Si {center_dot} contributing to the crosslinking reaction and that they are not resonance-stabilized by double bonds as the reaction mechanism in the irradiated polysilanes. However, the gelation curve in linear PMPS irradiated by 2 MeV He{sup +} is almost consistent with that in branching PMPS, indicating that the size of chemical track is responsible for the gel fraction. The crosslinking G value for high molecular weight PMPS irradiated by 2 MeV He{sup +} was drastically decreased as compared with that for low molecular weight. It suggests that there are a large number of intramolecular crosslinking points for high molecular weight PMPS. (author)

  19. CHROMOSPHERIC MODELS AND THE OXYGEN ABUNDANCE IN GIANT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Dupree, A. K.; Avrett, E. H.; Kurucz, R. L., E-mail: dupree@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2016-04-10

    Realistic stellar atmospheric models of two typical metal-poor giant stars in Omega Centauri, which include a chromosphere (CHR), influence the formation of optical lines of O i: the forbidden lines (λ6300, λ6363) and the infrared triplet (λλ7771−7775). One-dimensional semi-empirical non-local thermodynamic equilibrium (LTE) models are constructed based on observed Balmer lines. A full non-LTE formulation is applied for evaluating the line strengths of O i, including photoionization by the Lyman continuum and photoexcitation by Lyα and Lyβ. Chromospheric models (CHR) yield forbidden oxygen transitions that are stronger than those in radiative/convective equilibrium (RCE) models. The triplet oxygen lines from high levels also appear stronger than those produced in an RCE model. The inferred oxygen abundance from realistic CHR models for these two stars is decreased by factors of ∼3 as compared to values derived from RCE models. A lower oxygen abundance suggests that intermediate-mass AGB stars contribute to the observed abundance pattern in globular clusters. A change in the oxygen abundance of metal-poor field giants could affect models of deep mixing episodes on the red giant branch. Changes in the oxygen abundance can impact other abundance determinations that are critical to astrophysics, including chemical tagging techniques and galactic chemical evolution.

  20. Determining Ages of APOGEE Giants with Known Distances

    CERN Document Server

    Feuillet, Diane K; Holtzman, Jon; Girardi, Leo; MacDonald, Nick; Majewski, Steven R; Nidever, David L

    2015-01-01

    We present a sample of local red giant stars observed using the New Mexico State University 1 m telescope with the APOGEE spectrograph, for which we estimate stellar ages and the age distribution from the high-resolution spectroscopic stellar parameters and accurate distance measurements from Hipparcos. The high-resolution (R ~ 23,000), near infrared (H-band, 1.5-1.7 micron) APOGEE spectra provide measurements of the stellar atmospheric parameters (temperature, surface gravity, [M/H], and [alpha/M]). Due to the smaller uncertainties in surface gravity possible with high-resolution spectra and accurate Hipparcos distance measurements, we are able to calculate the stellar masses to within 40%. For red giants, the relatively rapid evolution of stars up the red giant branch allows the age to be constrained based on the mass. We examine methods of estimating age using both the mass-age relation directly and a Bayesian isochrone matching of measured parameters, assuming a constant star formation history (SFH). To i...

  1. Chromospheric Models and the Oxygen Abundance in Giant Stars

    Science.gov (United States)

    Dupree, A. K.; Avrett, E. H.; Kurucz, R. L.

    2016-04-01

    Realistic stellar atmospheric models of two typical metal-poor giant stars in Omega Centauri, which include a chromosphere (CHR), influence the formation of optical lines of O i: the forbidden lines (λ6300, λ6363) and the infrared triplet (λλ7771-7775). One-dimensional semi-empirical non-local thermodynamic equilibrium (LTE) models are constructed based on observed Balmer lines. A full non-LTE formulation is applied for evaluating the line strengths of O i, including photoionization by the Lyman continuum and photoexcitation by Lyα and Lyβ. Chromospheric models (CHR) yield forbidden oxygen transitions that are stronger than those in radiative/convective equilibrium (RCE) models. The triplet oxygen lines from high levels also appear stronger than those produced in an RCE model. The inferred oxygen abundance from realistic CHR models for these two stars is decreased by factors of ˜3 as compared to values derived from RCE models. A lower oxygen abundance suggests that intermediate-mass AGB stars contribute to the observed abundance pattern in globular clusters. A change in the oxygen abundance of metal-poor field giants could affect models of deep mixing episodes on the red giant branch. Changes in the oxygen abundance can impact other abundance determinations that are critical to astrophysics, including chemical tagging techniques and galactic chemical evolution.

  2. Hydraulic constraints modify optimal photosynthetic profiles in giant sequoia trees.

    Science.gov (United States)

    Ambrose, Anthony R; Baxter, Wendy L; Wong, Christopher S; Burgess, Stephen S O; Williams, Cameron B; Næsborg, Rikke R; Koch, George W; Dawson, Todd E

    2016-11-01

    Optimality theory states that whole-tree carbon gain is maximized when leaf N and photosynthetic capacity profiles are distributed along vertical light gradients such that the marginal gain of nitrogen investment is identical among leaves. However, observed photosynthetic N gradients in trees do not follow this prediction, and the causes for this apparent discrepancy remain uncertain. Our objective was to evaluate how hydraulic limitations potentially modify crown-level optimization in Sequoiadendron giganteum (giant sequoia) trees up to 90 m tall. Leaf water potential (Ψ l ) and branch sap flow closely followed diurnal patterns of solar radiation throughout each tree crown. Minimum leaf water potential correlated negatively with height above ground, while leaf mass per area (LMA), shoot mass per area (SMA), leaf nitrogen content (%N), and bulk leaf stable carbon isotope ratios (δ(13)C) correlated positively with height. We found no significant vertical trends in maximum leaf photosynthesis (A), stomatal conductance (g s), and intrinsic water-use efficiency (A/g s), nor in branch-averaged transpiration (E L), stomatal conductance (G S), and hydraulic conductance (K L). Adjustments in hydraulic architecture appear to partially compensate for increasing hydraulic limitations with height in giant sequoia, allowing them to sustain global maximum summer water use rates exceeding 2000 kg day(-1). However, we found that leaf N and photosynthetic capacity do not follow the vertical light gradient, supporting the hypothesis that increasing limitations on water transport capacity with height modify photosynthetic optimization in tall trees.

  3. Giant lipoma arising from deep lobe of the parotid gland

    Directory of Open Access Journals (Sweden)

    Hsu Ying-Che

    2006-06-01

    Full Text Available Abstract Background Lipomas are common benign soft tissue neoplasms but they are found very rarely in the deep lobe of parotid gland. Surgical intervention in these tumors is challenging because of the proximity of the facial nerve, and thus knowledge of the anatomy and meticulous surgical technique are essential. Case presentation A 71-year-old female presented with a large asymptomatic mass, which had occupied the left facial area for over the past fifteen years, and she requested surgical excision for a cosmetically better facial appearance. The computed tomography (CT scan showed a well-defined giant lipoma arising from the left deep parotid gland. The lipoma was successfully enucleated after full exposure and mobilization of the overlying facial nerve branches. The surgical specimen measured 9 × 6 cm in size, and histopathology revealed fibrolipoma. The patient experienced an uneventful recovery, with a satisfying facial contour and intact facial nerve function. Conclusion Giant lipomas involving the deep parotid lobe are extremely rare. The high-resolution CT scan provides an accurate and cost-effective preoperative investigative method. Surgical management of deep lobe lipoma should be performed by experienced surgeons due to the need for meticulous dissection of the facial nerve branches. Superficial parotidectomy before deep lobe lipoma removal may be unnecessary in selected cases because preservation of the superficial lobe may contribute to a better aesthetic and functional result.

  4. Principles of branch formation and branch patterning in Hydrozoa.

    Science.gov (United States)

    Berking, Stefan

    2006-01-01

    The freshwater polyp Hydra produces buds which separate from the parent. Other Hydrozoa produce branches which remain connected to the parent, thus forming a colony. Some Hydrozoa grow by means of an organ that is like a shoot apical meristem. Others display a sympodial type of growth. In this article, I propose that these different types of branches are organized by a common pattern-forming system. This system has self-organizing properties. It causes branch tip formation and is kept active in the tip when the tip finally differentiates into a hypostome of a polyp. The system does not cause structure formation directly but rather, determines a tissue property called positional value, in such a way that a gradient of values forms in the tissue of the bud or branch. The local value determines the local morphodynamic processes, including differentiation of the hypostome (highest positional value), tentacles and basal disc and of the exoskeleton pattern along the shoot. A high positional value favors the onset of a new self-organizing process and by lateral inhibition, such a process prevents the initiation of a further process in its surroundings. Small quantitative differences in the range of the signals involved determine whether a bud or a branch forms and whether monopodial and sympodial growth follows.

  5. Leonardo Da Vinci’s giant crossbow

    CERN Document Server

    Landrus, Matt

    2010-01-01

    Leonardo's Giant Crossbow is one of his least understood drawings. This fascinating book offers the first in-depth account of its likely purpose and its highly resolved design. It presents original research and new discoveries about the giant crossbow.

  6. A simple model to describe intrinsic stellar noise for exoplanet detection around red giants

    CERN Document Server

    North, Thomas S H; Gilliland, Ronald L; Huber, Daniel; Campante, Tiago L; Handberg, Rasmus; Lund, Mikkel N; Veras, Dimitri; Kuszlewicz, James S; Farr, Will M

    2016-01-01

    In spite of the huge advances in exoplanet research provided by the NASA Kepler Mission, there remain only a small number of transit detections around evolved stars. Here we present a reformulation of the noise properties of red-giant stars, where the intrinsic stellar granulation, and the stellar oscillations described by asteroseismology play a key role. The new noise model is a significant improvement on the current Kepler results for evolved stars. Our noise model may be used to help understand planet detection thresholds for the ongoing K2 and upcoming TESS missions, and serve as a predictor of stellar noise for these missions. As an application of our noise model, we explore the minimum detectable planet radii for red giant stars, and find that Neptune sized planets should be detectable around low luminosity red giant branch stars.

  7. A simple model to describe intrinsic stellar noise for exoplanet detection around red giants

    Science.gov (United States)

    North, Thomas S. H.; Chaplin, William J.; Gilliland, Ronald L.; Huber, Daniel; Campante, Tiago L.; Handberg, Rasmus; Lund, Mikkel N.; Veras, Dimitri; Kuszlewicz, James S.; Farr, Will M.

    2017-02-01

    In spite of the huge advances in exoplanet research provided by the NASA Kepler Mission, there remain only a small number of transit detections around evolved stars. Here, we present a reformulation of the noise properties of red-giant stars, where the intrinsic stellar granulation and the stellar oscillations described by asteroseismology play a key role. The new noise model is a significant improvement on the current Kepler results for evolved stars. Our noise model may be used to help understand planet detection thresholds for the ongoing K2 and upcoming TESSmissions, and serve as a predictor of stellar noise for these missions. As an application of our noise model, we explore the minimum detectable planet radii for red giant stars, and find that Neptune-sized planets should be detectable around low-luminosity red giant branch stars.

  8. A Color-Magnitude Diagram for a Globular Cluster In the Giant Elliptical Galaxy NGC 5128

    CERN Document Server

    Harris, G L H; Harris, W E

    1998-01-01

    The Hubble Space Telescope has been used to obtain WFPC2 (V,I) photometry for a large sample of stars in the outer halo of the giant elliptical NGC 5128 (d = 4 Mpc). The globular cluster N5128-C44, at the center of the Planetary Camera field, is well enough resolved to permit the construction of a color-magnitude diagram (CMD) for it which covers the brightest two magnitudes of the giant branch. The CMD is consistent with that of a normal old, moderately low-metallicity ([Fe/H] = -1.30 globular cluster, distinctly more metal-poor than most of the field halo stars at the same projected location (which average [Fe/H] ~ -0.5). This is the most distant globular cluster in which direct color-magnitude photometry has been achieved to date, and the first one belonging to a giant E galaxy.

  9. Atmospheres of Extrasolar Giant Planets

    Science.gov (United States)

    Marley, M. S.; Fortney, J.; Seager, S.; Barman, T.

    The key to understanding an extrasolar giant planet's spectrum - and hence its detectability and evolution - lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets (EGPs) are in hand, atmosphere models can be used to constrain atmospheric composition, thermal structure, and ultimately the formation and evolution of detected planets. We review the important physical processes that influence the atmospheric structure and evolution of EGPs and consider what has already been learned from the first generation of observations and modeling. We pay particular attention to the roles of cloud structure, metallicity, and atmospheric chemistry in affecting detectable properties through Spitzer Space Telescope observations of the transiting giant planets. Our review stresses the uncertainties that ultimately limit our ability to interpret EGP observations. Finally we will conclude with a look to the future as characterization of multiple individual planets in a single stellar system leads to the study of comparative planetary architectures.

  10. Giant lobelias exemplify convergent evolution.

    Science.gov (United States)

    Givnish, Thomas J

    2010-01-14

    Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution.

  11. Giant lobelias exemplify convergent evolution

    Directory of Open Access Journals (Sweden)

    Givnish Thomas J

    2010-01-01

    Full Text Available Abstract Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution.

  12. Structure of giant muscle proteins

    Directory of Open Access Journals (Sweden)

    Nathan Thompson Wright

    2013-12-01

    Full Text Available Giant muscle proteins (e.g. titin, nebulin, and obscurin play a seminal role in muscle elasticity, stretch response, and sarcomeric organization. Each giant protein consists of multiple tandem structural domains, usually arranged in a modular fashion ranging from 500 kDa to 4 MDa. Although many of the domains are similar in structure, subtle differences create a unique function of each domain. Recent high and low resolution structural and dynamic studies now suggest more nuanced overall protein structures than previously realized. These findings show that atomic structure, interactions between tandem domains, and intrasarcomeric environment all influence the shape, motion, and therefore function of giant proteins. In this article we will review the current understanding of titin, obscurin, and nebulin structure, from the atomic level through the molecular level.

  13. Structural glitches near the cores of red giants revealed by oscillations in g-mode period spacings from stellar models

    CERN Document Server

    Cunha, M S; Avelino, P P; Christensen-Dalsgaard, J; Townsend, R H D

    2015-01-01

    With recent advances in asteroseismology it is now possible to peer into the cores of red giants, potentially providing a way to study processes such as nuclear burning and mixing through their imprint as sharp structural variations -- glitches -- in the stellar cores. Here we show how such core glitches can affect the oscillations we observe in red giants. We derive an analytical expression describing the expected frequency pattern in the presence of a glitch. This formulation also accounts for the coupling between acoustic and gravity waves. From an extensive set of canonical stellar models we find glitch-induced variation in the period spacing and inertia of non-radial modes during several phases of red-giant evolution. Significant changes are seen in the appearance of mode amplitude and frequency patterns in asteroseismic diagrams such as the power spectrum and the \\'echelle diagram. Interestingly, along the red-giant branch glitch-induced variation occurs only at the luminosity bump, potentially providin...

  14. Photovoltaic measurements and performance branch

    Science.gov (United States)

    Asher, S. E.; Dippo, P.

    1990-05-01

    The Photovoltaic (PV) Measurements and Performance Branch of the Solar Energy Research Institute (SERI) provides comprehensive PV materials, device and component characterization, measurement, fabrication, and modeling research and support for the international PV research community in the context of the U.S. Department of Energy's PV m goals. The progress of the Branch is summarized. The seven technical sections present a succinct overview of the capabilities and accomplishments of each group in the Branch. The Branch is comprised of the following groups; Surface and Interface Analysis, Materials Characterization, Device Development, Electro-Optical Characterization, Cell Performance, Advanced Module Testing and Performance, and Surface and Interface Modification and Stability. The main research projects completed in FY 1989 are highlighted including measurements and tests of PV materials, cells, submodules and modules. The report contains a comprehensive bibliography of the more than 80 branch-originated journal and conference publications which were authored in collaboration with, or in support of, approximately 130 university, industrial, government, and in-house research groups.

  15. THE SEGUE K GIANT SURVEY. III. QUANTIFYING GALACTIC HALO SUBSTRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Janesh, William; Morrison, Heather L.; Ma, Zhibo; Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Rockosi, Constance [UCO/Lick Observatory, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Starkenburg, Else [Department of Physics and Astronomy, University of Victoria, P.O. Box 1700, STN CSC, Victoria BC V8W 3P6 (Canada); Xue, Xiang Xiang; Rix, Hans-Walter [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Beers, Timothy C. [Department of Physics and JINA Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, IN 46556 (United States); Johnson, Jennifer [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Lee, Young Sun [Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134 (Korea, Republic of); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-01-10

    We statistically quantify the amount of substructure in the Milky Way stellar halo using a sample of 4568 halo K giant stars at Galactocentric distances ranging over 5–125 kpc. These stars have been selected photometrically and confirmed spectroscopically as K giants from the Sloan Digital Sky Survey’s Sloan Extension for Galactic Understanding and Exploration project. Using a position–velocity clustering estimator (the 4distance) and a model of a smooth stellar halo, we quantify the amount of substructure in the halo, divided by distance and metallicity. Overall, we find that the halo as a whole is highly structured. We also confirm earlier work using blue horizontal branch (BHB) stars which showed that there is an increasing amount of substructure with increasing Galactocentric radius, and additionally find that the amount of substructure in the halo increases with increasing metallicity. Comparing to resampled BHB stars, we find that K giants and BHBs have similar amounts of substructure over equivalent ranges of Galactocentric radius. Using a friends-of-friends algorithm to identify members of individual groups, we find that a large fraction (∼33%) of grouped stars are associated with Sgr, and identify stars belonging to other halo star streams: the Orphan Stream, the Cetus Polar Stream, and others, including previously unknown substructures. A large fraction of sample K giants (more than 50%) are not grouped into any substructure. We find also that the Sgr stream strongly dominates groups in the outer halo for all except the most metal-poor stars, and suggest that this is the source of the increase of substructure with Galactocentric radius and metallicity.

  16. Giant intravesical calculus during pregnancy.

    Science.gov (United States)

    Escobar-del Barco, Laura; Rodriguez-Colorado, Silvia; Dueñas-Garcia, Omar Felipe; Avilez-Cevasco, Juan Carlos

    2008-10-01

    Urolithiasis is commonly found during pregnancy; but the presence of a giant vesical calculus during pregnancy is a very rare entity, associated with several potential obstetric complications. A 25-year-old primigravida at 25 weeks of gestational age was referred to our tertiary care unit because she presented a giant hyperechoic intravesical mass and inability to pass urine with suprapubic pain since 2 days. An open cystolithotomy revealed a huge intravesical calculus. The patient continued with her pregnancy until full term without adverse perinatal outcomes.

  17. Giant fields in southwest Mexico

    Energy Technology Data Exchange (ETDEWEB)

    1981-07-20

    According to Petroleos Mexicanos southeastern Mexico's Isthmus Saline basin holds five new giant fields - Tonala-El Burro, El Plan, Cinco Presidentes, Oraggio, and Magallanes - producing oil and gas from Tertiary sandstones. Numerous normal faults resulting from salt intrusion have given rise to multiple blocks, each with its own reservoir conditions. Previously discovered basins in the area include the Macuspana, which holds three giant gas- and condensate-producing fields: Jose Colomo, Chilapilla, and Hormiquero. The 3100-mi/sup 2/ Campeche marine platform, extending offshore nearby, contains the Cantarell complex, Mexico's most productive hydrocarbon province.

  18. Discovery of radiatively excited molecular hydrogen in the giant extragalactic HII region complex NGC 604

    NARCIS (Netherlands)

    Israel, F.P.; Hawarden, T.G.; Wade, R.S.; Geballe, T.R.; Dishoeck, van E.F.

    1989-01-01

    The 1-0S(1), 2-1S(1), 1-0S(0) and 1-0Q branch transitions of molecular hydrogen (H2) towards the giant emission nebula (HII region) NGC 604 in M33 have been detected. The line ratios are incompatible with shock-excited H2, but indicate the widespread presence of fluorescent H2 at a mean temperature

  19. Globular and Open Clusters Observed by SDSS/SEGUE: the Giant Stars

    CERN Document Server

    Morrison, Heather L; Clem, James L; An, Deokkeun; Connor, Thomas; Schechtman-Rook, Andrew; Harding, Paul; Casagrande, Luca; Rockosi, Constance; Yanny, Brian; Beers, Timothy C; Johnson, Jennifer A; Schneider, Donald P

    2015-01-01

    We present griz observations for the clusters M92, M13 and NGC 6791 and gr photometry for M71, Be 29 and NGC 7789. In addition we present new membership identifications for all these clusters, which have been observed spectroscopically as calibrators for the SDSS/SEGUE survey; this paper focuses in particular on the red giant branch stars in the clusters. In a number of cases, these giants were too bright to be observed in the normal SDSS survey operations, and we describe the procedure used to obtain spectra for these stars. For M71, also present a new variable reddening map and a new fiducial for the gr giant branch. For NGC 7789, we derived a transformation from Teff to g-r for giants of near solar abundance, using IRFM Teff measures of stars with good ugriz and 2MASS photometry and SEGUE spectra. The result of our analysis is a robust list of known cluster members with correctly dereddened and (if needed) transformed gr photometry for crucial calibration efforts for SDSS and SEGUE.

  20. GLOBULAR AND OPEN CLUSTERS OBSERVED BY SDSS/SEGUE: THE GIANT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Heather L.; Ma, Zhibo; Connor, Thomas; Schechtman-Rook, Andrew; Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Clem, James L. [Department of Physics, Grove City College, 100 Campus Dr., Grove City, PA 16127 (United States); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Casagrande, Luca [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, ACT 2611 (Australia); Rockosi, Constance [UCO/Lick Observatory, University of California, Santa Cruz, 1156 High St., Santa Cruz, CA 95064 (United States); Yanny, Brian [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia IL 60510 (United States); Beers, Timothy C. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46656 (United States); Johnson, Jennifer A. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Schneider, Donald P., E-mail: hlm5@case.edu [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-01-15

    We present griz observations for the clusters M92, M13 and NGC 6791 and gr photometry for M71, Be 29 and NGC 7789. In addition we present new membership identifications for all these clusters, which have been observed spectroscopically as calibrators for the Sloan Digital Sky Survey (SDSS)/SEGUE survey; this paper focuses in particular on the red giant branch stars in the clusters. In a number of cases, these giants were too bright to be observed in the normal SDSS survey operations, and we describe the procedure used to obtain spectra for these stars. For M71, we also present a new variable reddening map and a new fiducial for the gr giant branch. For NGC 7789, we derived a transformation from T{sub eff} to g–r for giants of near solar abundance, using IRFM T{sub eff} measures of stars with good ugriz  and 2MASS photometry and SEGUE spectra. The result of our analysis is a robust list of known cluster members with correctly dereddened and (if needed) transformed gr photometry for crucial calibration efforts for SDSS and SEGUE.

  1. Stripped red giants - Helium core white dwarf progenitors and their sdB siblings

    CERN Document Server

    Heber, Ulrich

    2016-01-01

    Some gaps in the mosaic of binary star evolution have recently been filled by the discoveries of helium-core white dwarf progenitors (often called extremely low mass (ELM) white dwarfs) as stripped cores of first-giant branch objects. Two varieties can be distinguished. One class is made up by SB1 binaries, companions being white dwarfs as well, another class, the so-called EL CVn stars, are composite spectrum binaries, with A-Type companions. Pulsating stars are found among both classes. A riddle is posed by the apparently single objects. There is a one-to-one correspondence of the phenomena found for these new classes of star to those observed for sdB stars. In fact, standard evolutionary scenarios explain the origin of sdB stars as red giants that have been stripped close to the tip of first red giant branch. A subgroup of subluminous B stars can also be identified as stripped helium-cores of red giants. They form an extension of the ELM sequence to higher temperatures. Hence low mass white dwarfs of heliu...

  2. Stripped Red Giants - Helium Core White Dwarf Progenitors and their sdB Siblings

    Science.gov (United States)

    Heber, U.

    2017-03-01

    Some gaps in the mosaic of binary star evolution have recently been filled by the discoveries of helium-core white dwarf progenitors (often called extremely low mass (ELM) white dwarfs) as stripped cores of first-giant branch objects. Two varieties can be distinguished. One class is made up by SB1 binaries, companions being white dwarfs as well. Another class, the so-called EL CVn stars, are composite spectrum binaries, with A-Type companions. Pulsating stars are found among both classes. A riddle is posed by the apparently single objects. There is a one-to-one correspondence of the phenomena found for these new classes of star to those observed for sdB stars. In fact, standard evolutionary scenarios explain the origin of sdB stars as red giants that have been stripped close to the tip of first red giant branch. A subgroup of subluminous B stars can also be identified as stripped helium-cores of red giants. They form an extension of the ELM sequence to higher temperatures. Hence low mass white dwarfs of helium cores and sdB stars in binaries are close relatives in terms of stellar evolution.

  3. Multiple pathways regulate shoot branching

    Directory of Open Access Journals (Sweden)

    Catherine eRameau

    2015-01-01

    Full Text Available Shoot branching patterns result from the spatio-temporal regulation of axillary bud outgrowth. Numerous endogenous, developmental and environmental factors are integrated at the bud and plant levels to determine numbers of growing shoots. Multiple pathways that converge to common integrators are most probably involved. We propose several pathways involving not only the classical hormones auxin, cytokinins and strigolactones, but also other signals with a strong influence on shoot branching such as gibberellins, sugars or molecular actors of plant phase transition. We also deal with recent findings about the molecular mechanisms and the pathway involved in the response to shade as an example of an environmental signal controlling branching. We propose the TCP transcription factor TB1/BRC1 and the polar auxin transport stream in the stem as possible integrators of these pathways. We finally discuss how modeling can help to represent this highly dynamic system by articulating knowledges and hypothesis and calculating the phenotype properties they imply.

  4. Warped branches of flux compactifications

    CERN Document Server

    Lim, Yen-Kheng

    2012-01-01

    We consider Freund-Rubin-type compactifications which are described by (p+q)-dimensional Einstein gravity with a positive cosmological constant and a q-form flux. Using perturbative expansions of Kinoshita's ansatz for warped dS_pxS^q and AdS_pxS^q spacetimes, we obtain analytical solutions describing the warped branches and their respective phase spaces. These equations are given by inhomogeneous Gegenbauer differential equations which can be solved by the Green's function method. The requirement that the Green's functions are regular provides constraints which determine the structure of the phase space of the warped branches. We apply the perturbation results to calculate the thermodynamic variables for the warped dS_pxS^q branch. In particular, the first law of thermodynamics can be reproduced using this method.

  5. 30 CFR 56.6403 - Branch circuits.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Branch circuits. 56.6403 Section 56.6403... Blasting § 56.6403 Branch circuits. (a) If electric blasting includes the use of branch circuits, each branch shall be equipped with a safety switch or equivalent method to isolate the circuits to be used....

  6. 30 CFR 57.6403 - Branch circuits.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Branch circuits. 57.6403 Section 57.6403... Blasting-Surface and Underground § 57.6403 Branch circuits. (a) If electric blasting includes the use of branch circuits, each branch shall be equipped with a safety switch or equivalent method to isolate...

  7. CARBON ABUNDANCES FOR RED GIANTS IN THE DRACO DWARF SPHEROIDAL GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Shetrone, Matthew D.; Stanford, Laura M. [McDonald Observatory, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712-0259 (United States); Smith, Graeme H. [University of California ObservatoriesLick Observatory, Department of Astronomy and Astrophysics, UC Santa Cruz, 1156 High St., Santa Cruz, CA 95064 (United States); Siegel, Michael H. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, State College, PA 16801 (United States); Bond, Howard E., E-mail: shetrone@astro.as.utexas.edu, E-mail: graeme@ucolick.org, E-mail: siegel@astro.psu.edu, E-mail: bond@stsci.edu [9615 Labrador Ln., Cockeysville, MD 21030 (United States)

    2013-05-15

    Measurements of [C/Fe], [Ca/H], and [Fe/H] have been derived from Keck I LRISb spectra of 35 giants in the Draco dwarf spheroidal galaxy. The iron abundances are derived by a spectrum synthesis modeling of the wavelength region from 4850 to 5375 A, while calcium and carbon abundances are obtained by fitting the Ca II H and K lines and the CH G band, respectively. A range in metallicity of -2.9 {<=} [Fe/H] {<=} -1.6 is found within the giants sampled, with a good correlation between [Fe/H] and [Ca/H]. The great majority of stars in the sample would be classified as having weak absorption in the {lambda}3883 CN band, with only a small scatter in band strengths at a given luminosity on the red giant branch. In this sense the behavior of CN among the Draco giants is consistent with the predominantly weak CN bands found among red giants in globular clusters of metallicity [Fe/H] < -1.8. Over half of the giants in the Draco sample have [Fe/H] > -2.25, and among these there is a trend for the [C/Fe] abundance to decrease with increasing luminosity on the red giant branch. This is a phenomenon that is also seen among both field and globular cluster giants of the Galactic halo, where it has been interpreted as a consequence of deep mixing of material between the base of the convective envelope and the outer limits of the hydrogen-burning shell. However, among the six Draco giants observed that turn out to have metallicities -2.65 < [Fe/H] < -2.25 there is no such trend seen in the carbon abundance. This may be due to small sample statistics or primordial inhomogeneities in carbon abundance among the most metal-poor Draco stars. We identify a potential carbon-rich extremely metal-poor star in our sample. This candidate will require follow-up observations for confirmation.

  8. Giant lipomas of the hand

    Directory of Open Access Journals (Sweden)

    Gokce Yildiran

    2015-04-01

    Conclusion: Giant lipomas of the hand are very rare and may cause compressions and other complications. Thus, they require a careful preoperative evaluation in order to make a proper differential diagnosis. [Hand Microsurg 2015; 4(1.000: 8-11

  9. A Giant or a Dwarf?

    DEFF Research Database (Denmark)

    Schmid, Herman

    2005-01-01

    EU may appear to be a giant when it can act on behalf of a united Europe, but usually it is hampered by conflicting member state interests. The EU economic and administrative resources for foreign and trade policy are quite small (on level with one of its major member states) and the hopes in man...

  10. The giant panda gut microbiome.

    Science.gov (United States)

    Wei, Fuwen; Wang, Xiao; Wu, Qi

    2015-08-01

    Giant pandas (Ailuropoda melanoleuca) are bamboo specialists that evolved from carnivores. Their gut microbiota probably aids in the digestion of cellulose and this is considered an example of gut microbiota adaptation to a bamboo diet. However, this issue remains unresolved and further functional and compositional studies are needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Michigan has a sleeping giant

    CERN Multimedia

    Brock, Raymond; Nichols, Sue

    2007-01-01

    "That giant is 750 miles of fiber optic cable that lassoes its three biggest research universities and Van Andel Institute to the future. Its mission: to uncover the nature of the Big Bang by connecton U.S. physicists to their huge experiment ATLAS in Geneva.." (4 pages)

  12. Multiphonon giant resonances in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Bortignon, P.F. [Milan Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Emling, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    1998-07-01

    We review the present knowledge of multiphonon giant resonances in nuclei. Theoretical concepts approaching the intrinsic structure and excitation mechanisms of multi-phonon states are discussed. The available experimental results are summarized, including a brief description of applied techniques. This review emphasizes electromagnetic excitations of double dipole resonances. Open questions and possible routes toward a solution are addressed. (orig.)

  13. A Giant or a Dwarf?

    DEFF Research Database (Denmark)

    Schmid, Herman

    2005-01-01

    EU may appear to be a giant when it can act on behalf of a united Europe, but usually it is hampered by conflicting member state interests. The EU economic and administrative resources for foreign and trade policy are quite small (on level with one of its major member states) and the hopes in man...

  14. Cloud formation in giant planets

    CERN Document Server

    Helling, Christiane

    2007-01-01

    We calculate the formation of dust clouds in atmospheres of giant gas-planets. The chemical structure and the evolution of the grain size distribution in the dust cloud layer is discussed based on a consistent treatment of seed formation, growth/evaporation and gravitational settling. Future developments are shortly addressed.

  15. Strigolactone inhibition of shoot branching

    NARCIS (Netherlands)

    Gomez-Roldan, M.V.; Fermas, S.; Brewer, P.B.; Puech-Pages, V.; Dun, E.A.; Pillot, J.P.; Letisse, F.; Matusova, R.; Danoun, S.; Portais, J.C.; Bouwmeester, H.J.; Becard, G.; Beveridge, C.A.; Rameau, C.; Rochange, S.F.

    2008-01-01

    A carotenoid-derived hormonal signal that inhibits shoot branching in plants has long escaped identification. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Here we present evidence

  16. Strigolactone inhibition of shoot branching

    NARCIS (Netherlands)

    Gomez-Roldan, M.V.; Fermas, S.; Brewer, P.B.; Puech-Pages, V.; Dun, E.A.; Pillot, J.P.; Letisse, F.; Matusova, R.; Danoun, S.; Portais, J.C.; Bouwmeester, H.J.; Becard, G.; Beveridge, C.A.; Rameau, C.; Rochange, S.F.

    2008-01-01

    A carotenoid-derived hormonal signal that inhibits shoot branching in plants has long escaped identification. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Here we present evidence

  17. Cash efficiency for bank branches.

    Science.gov (United States)

    Cabello, Julia García

    2013-01-01

    Bank liquidity management has become a major issue during the financial crisis as liquidity shortages have intensified and have put pressure on banks to diversity and improve their liquidity sources. While a significant strand of the literature concentrates on wholesale liquidity generation and on the alternative to deposit funding, the management of an inventory of cash holdings within the banks' branches is also a relevant issue as any significant improvement in cash management at the bank distribution channels may have a positive effect in reducing liquidity tensions. In this paper, we propose a simple programme of cash efficiency for the banks' branches, very easy to implement, which conform to a set of instructions to be imposed from the bank to their branches. This model proves to significantly reduce cash holdings at branches thereby providing efficiency improvements in liquidity management. The methodology we propose is based on the definition of some stochastic processes combined with renewal processes, which capture the random elements of the cash flow, before applying suitable optimization programmes to all the costs involved in cash movements. The classical issue of the Transaction Demand for the Cash and some aspects of Inventory Theory are also present. Mathematics Subject Classification (2000) C02, C60, E50.

  18. Branching of keratin intermediate filaments.

    Science.gov (United States)

    Nafeey, Soufi; Martin, Ines; Felder, Tatiana; Walther, Paul; Felder, Edward

    2016-06-01

    Keratin intermediate filaments (IFs) are crucial to maintain mechanical stability in epithelial cells. Since little is known about the network architecture that provides this stiffness and especially about branching properties of filaments, we addressed this question with different electron microscopic (EM) methods. Using EM tomography of high pressure frozen keratinocytes, we investigated the course of several filaments in a branching of a filament bundle. Moreover we found several putative bifurcations in individual filaments. To verify our observation we also visualized the keratin network in detergent extracted keratinocytes with scanning EM. Here bifurcations of individual filaments could unambiguously be identified additionally to bundle branchings. Interestingly, identical filament bifurcations were also found in purified keratin 8/18 filaments expressed in Escherichia coli which were reassembled in vitro. This excludes that an accessory protein contributes to the branch formation. Measurements of the filament cross sectional areas showed various ratios between the three bifurcation arms. This demonstrates that intermediate filament furcation is very different from actin furcation where an entire new filament is attached to an existing filament. Instead, the architecture of intermediate filament bifurcations is less predetermined and hence consistent with the general concept of IF formation.

  19. NCI: DCTD: Biometric Research Branch

    Science.gov (United States)

    The Biometric Research Branch (BRB) is the statistical and biomathematical component of the Division of Cancer Treatment, Diagnosis and Centers (DCTDC). Its members provide statistical leadership for the national and international research programs of the division in developmental therapeutics, developmental diagnostics, diagnostic imaging and clinical trials.

  20. Mapping Milky Way Halo Structure with Blue Horizontal Branch Stars

    Science.gov (United States)

    Martin, Charles; Newberg, Heidi Jo; Carlin, Jeffrey L.

    2017-01-01

    The use of blue horizontal brach (BHB) and red giant branch stars as tracers of stellar debris streams is a common practice and has been useful in the confirmation of kinematic properties of previously identified streams. This work explores less common ways of untangling the velocity signatures of streams traveling radially to our line of sight, and to peer toward the higher density region of the Galactic Center using data from the Sloan Digital Sky Survey (SDSS). Using spectra of BHB stars, we are able to kinematically distinguish moving groups in the Milky Way halo. The results of this thesis advance our knowledge of the following stellar halo substructures: the Pisces Stellar Stream, the Hercules-Aquila Cloud, the Hercules Halo Stream, and the Hermus Stream. A study of red giant stars led to the kinematic discovery of the Pisces Stellar Stream. Red giant stars were also examined to determine that the previously identified velocity signature that was suggested for the Hercules-Aquila Cloud was due to disk star contamination and errors in preliminary SDSS velocities. The Hercules Halo Stream is a previously unidentified structure that could be related to the Hercules-Aquila Cloud, and was discovered as a velocity excess of SDSS BHB stars. We identify a group of 10 stars with similar velocities that are spatially coincident with the Hermus Stream. An orbit is fit to the Hermus Stream that rules out a connection with the Phoenix Stream.This work was supported by NSF grants AST 09-37523, 14-09421, 16-15688, the NASA/NY Space Grant fellowship, and contributions made by The Marvin Clan, Babette Josephs, Manit Limlamai, and the 2015 Crowd Funding Campaign to Support Milky Way Research.

  1. Star-planet interactions: II. Is planet engulfment the origin of fast rotating red giants?

    CERN Document Server

    Privitera, Giovanni; Eggenberger, Patrick; Vidotto, Aline A; Villaver, Eva; Bianda, Michele

    2016-01-01

    Context. Fast rotating red giants in the upper part of the red giant branch have surface velocities that cannot be explained by single star evolution. Aims. We check whether tides between a star and a planet followed by planet engulfment can indeed accelerate the surface rotation of red giants for a sufficient long time in order to produce these fast rotating red giants. Methods. Using rotating stellar models, accounting for the redistribution of the angular momentum inside the star by different transport mechanisms, for the exchanges of angular momentum between the planet orbit and the star before the engulfment and for the deposition of angular momentum inside the star at the engulfment, we study how the surface rotation velocity at the stellar surface evolves. Results. We show that the surface velocities reached at the end of the orbital decay due to tidal forces and planet engulfment can be similar to values observed for fast rotating red giants. This surface velocity then decreases when the star evolves ...

  2. Star-planet interactions. II. Is planet engulfment the origin of fast rotating red giants?

    Science.gov (United States)

    Privitera, Giovanni; Meynet, Georges; Eggenberger, Patrick; Vidotto, Aline A.; Villaver, Eva; Bianda, Michele

    2016-10-01

    Context. Fast rotating red giants in the upper part of the red giant branch have surface velocities that cannot be explained by single star evolution. Aims: We check whether tides between a star and a planet followed by planet engulfment can indeed accelerate the surface rotation of red giants for a sufficiently long time to produce these fast rotating red giants. Methods: We studied how the surface rotation velocity at the stellar surface evolves using rotating stellar models, accounting for the redistribution of the angular momentum inside the star by different transport mechanisms, the exchanges of angular momentum between the planet orbit and the star before the engulfment, and for the deposition of angular momentum inside the star at the engulfment. We considered different situations with masses of stars in the range between 1.5 and 2.5 M⊙, masses of the planets between 1 and 15 MJ (Jupiter mass), and initial semimajor axis between 0.5 and 1.5 au. The metallicity Z for our stellar models is 0.02. Results: We show that the surface velocities reached at the end of the orbital decay due to tidal forces and planet engulfment can be similar to values observed for fast rotating red giants. This surface velocity then decreases when the star evolves along the red giant branch but at a sufficiently slow pace to allowing stars to be detected with such a high velocity. More quantitatively, star-planet interaction can produce a rapid acceleration of the surface of the star, above values equal to 8 km s-1, for periods lasting up to more than 30% the red giant branch phase. As found already by previous works, the changes of the surface carbon isotopic ratios produced by the dilution of the planetary material into the convective envelope is modest. The increase of the lithium abundance due to this effect might be much more important, however lithium may be affected by many different, still uncertain, processes. Thus any lithium measurement can hardly be taken as a support

  3. CHEMICAL ABUNDANCES IN FIELD RED GIANTS FROM HIGH-RESOLUTION H-BAND SPECTRA USING THE APOGEE SPECTRAL LINELIST

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Verne V.; Cunha, Katia [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Shetrone, Matthew D. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Meszaros, Szabolcs; Allende Prieto, Carlos [Instituto d' Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain); Bizyaev, Dmitry [Apache Point Observatory, Sunspot, NM 88349 (United States); Garcia Perez, Ana; Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Schiavon, Ricardo [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5UX (United Kingdom); Holtzman, Jon [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Johnson, Jennifer A., E-mail: vsmith@noao.edu [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States)

    2013-03-01

    High-resolution H-band spectra of five bright field K, M, and MS giants, obtained from the archives of the Kitt Peak National Observatory Fourier transform spectrometer, are analyzed to determine chemical abundances of 16 elements. The abundances were derived via spectrum synthesis using the detailed linelist prepared for the Sloan Digital Sky Survey III Apache Point Galactic Evolution Experiment (APOGEE), which is a high-resolution near-infrared spectroscopic survey to derive detailed chemical abundance distributions and precise radial velocities for 100,000 red giants sampling all Galactic stellar populations. The red giant sample studied here was chosen to probe which chemical elements can be derived reliably from the H-band APOGEE spectral region. These red giants consist of two K-giants ({alpha} Boo and {mu} Leo), two M-giants ({beta} And and {delta} Oph), and one thermally pulsing asymptotic giant branch (TP-AGB) star of spectral type MS (HD 199799). Measured chemical abundances include the cosmochemically important isotopes {sup 12}C, {sup 13}C, {sup 14}N, and {sup 16}O, along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The K and M giants exhibit the abundance signature of the first dredge-up of CN-cycle material, while the TP-AGB star shows clear evidence of the addition of {sup 12}C synthesized during {sup 4}He-burning thermal pulses and subsequent third dredge-up. A comparison of the abundances derived here with published values for these stars reveals consistent results to {approx}0.1 dex. The APOGEE spectral region and linelist is thus well suited for probing both Galactic chemical evolution, as well as internal nucleosynthesis and mixing in populations of red giants via high-resolution spectroscopy.

  4. Streamers in air splitting into three branches

    CERN Document Server

    Heijmans, L C J; van Veldhuizen, E M; Ebert, U

    2013-01-01

    We investigate the branching of positive streamers in air and present the first systematic investigation of splitting into more than two branches. We study discharges in 100 mbar artificial air that is exposed to voltage pulses of 10 kV applied to a needle electrode 160 mm above a grounded plate. By imaging the discharge with two cameras from three angles, we establish that about every 200th branching event is a branching into three. Branching into three occurs more frequently for the relatively thicker streamers. In fact, we find that the surface of the total streamer cross-sections before and after a branching event is roughly the same.

  5. BDC 500 branch driver controller

    CERN Document Server

    Dijksman, A

    1981-01-01

    This processor has been designed for very fast data acquisition and date pre-processing. The dataway and branch highway speeds have been optimized for approximately 1.5 mu sec. The internal processor cycle is approximately 0.8 mu sec. The standard version contains the following functions (slots): crate controller type A1; branch highway driver including terminator; serial I/O port (TTY, VDU); 24 bit ALU and 24 bit program counter; 16 bit memory address counter and 4 word stack; 4k bit memory for program and/or data; battery backup for the memory; CNAFD and crate LAM display; request/grant logic for time- sharing operation of several BDCs. The free slots can be equipped with e.g. extra RAM, computer interfaces, hardware multiplier/dividers, etc. (0 refs).

  6. Asteroseismology of Red Giant stars

    CERN Document Server

    Tarrant, N J; Elsworth, Y P; Spreckley, S A; Stevens, I R

    2008-01-01

    Sun-like oscillations, that is p-modes excited stochastically by convective noise, have now been observed in a number of Red Giant stars. Compared to those seen in the Sun, these modes are of large amplitude and long period, making the oscillations attractive prospects for observation. However, the low Q-factor of these modes, and issues relating to the rising background at low frequencies, present some interesting challenges for identifying modes and determining the related asteroseismic parameters. We report on the analysis procedure adopted for peak-bagging by our group at Birmingham, and the techniques used to robustly ensure these are not a product of noise. I also show results from a number of giants extracted from multi-year observations with the SMEI instrument.

  7. Giant condyloma acuminatum of vulva

    Directory of Open Access Journals (Sweden)

    S. M. Ramiz Ahmed

    2017-09-01

    Full Text Available In this paper, A 23 year old married woman who was diagnosed as a case of giant condyloma acuminatum of vulva measuring about 15 x 8 x 3 cm, irregular surface with multiple projections, oval in shape, firm to hard in consistency, mildly tender, exophytic, cauliflower like growth involving the whole vulva (lower part of mons pubis, labia, vestibule, clitoris, around vaginal opening. Another multiple small lesions were present at perineal region but there was no inguinal lymphadenopathy. She underwent a combined electro cauterization and cryotherapy for small to moderate size multiple primary and recurrent warty lesions and wide surgical excision with fasciocutaneous advancement flaps procedure for a giant lesions in the vulva. Excisional biopsies were performed to detect potential malignancy but malignancy was not found histologically. The patient was advised to first follow-up 1 month after operation when multiple small warty lesions were developed and treated and the subsequent follow-ups for 3 months.

  8. Solid State Photovoltaic Research Branch

    Energy Technology Data Exchange (ETDEWEB)

    1990-09-01

    This report summarizes the progress of the Solid State Photovoltaic Research Branch of the Solar Energy Research Institute (SERI) from October 1, 1988, through September 30,l 1989. Six technical sections of the report cover these main areas of SERIs in-house research: Semiconductor Crystal Growth, Amorphous Silicon Research, Polycrystalline Thin Films, III-V High-Efficiency Photovoltaic Cells, Solid-State Theory, and Laser Raman and Luminescence Spectroscopy. Sections have been indexed separately for inclusion on the data base.

  9. Idiopathic giant right atrial aneurysm

    Science.gov (United States)

    Uppu, Santosh C; Sachdeva, Ritu; Imamura, Michiaki

    2013-01-01

    A 2-year-old boy with an incidental finding of massive cardiomegaly on a chest X-ray was diagnosed with a giant right atrial aneurysm upon further investigation with echocardiography. The patient underwent successful surgical reduction of the right atrium and closure of the patent foramen ovale to prevent thromboembolic complications and to lower the risk of atrial arrhythmias. The resected atrium had paper-thin walls and pathological features of interstitial fibrosis with endocardial thickening. PMID:23626440

  10. Idiopathic giant right atrial aneurysm

    OpenAIRE

    Uppu, Santosh C; Ritu Sachdeva; Michiaki Imamura

    2013-01-01

    A 2-year-old boy with an incidental finding of massive cardiomegaly on a chest X-ray was diagnosed with a giant right atrial aneurysm upon further investigation with echocardiography. The patient underwent successful surgical reduction of the right atrium and closure of the patent foramen ovale to prevent thromboembolic complications and to lower the risk of atrial arrhythmias. The resected atrium had paper-thin walls and pathological features of interstitial fibrosis with endocardial thicken...

  11. Giant sialocele following facial trauma

    OpenAIRE

    Medeiros Júnior,Rui; Rocha Neto,Alípio Miguel da; Queiroz, Isaac Vieira; Cauby,Antônio de Figueiredo; Gueiros,Luiz Alcino Monteiro; Leão,Jair Carneiro

    2012-01-01

    Injuries in the parotid and masseter region can cause serious impairment secondary to damage of important anatomical structures. Sialocele is observed as facial swelling associated with parotid duct rupture due to trauma. The aim of this paper is to report a case of a giant traumatic sialocele in the parotid gland, secondary to a knife lesion in a 40-year-old woman. Conservative measures could not promote clinical resolution and a surgical intervention for the placement of a vacuum drain was ...

  12. Idiopathic giant right atrial aneurysm

    Directory of Open Access Journals (Sweden)

    Santosh C Uppu

    2013-01-01

    Full Text Available A 2-year-old boy with an incidental finding of massive cardiomegaly on a chest X-ray was diagnosed with a giant right atrial aneurysm upon further investigation with echocardiography. The patient underwent successful surgical reduction of the right atrium and closure of the patent foramen ovale to prevent thromboembolic complications and to lower the risk of atrial arrhythmias. The resected atrium had paper-thin walls and pathological features of interstitial fibrosis with endocardial thickening.

  13. Branching processes and neutral evolution

    CERN Document Server

    Taïb, Ziad

    1992-01-01

    The Galton-Watson branching process has its roots in the problem of extinction of family names which was given a precise formulation by F. Galton as problem 4001 in the Educational Times (17, 1873). In 1875, an attempt to solve this problem was made by H. W. Watson but as it turned out, his conclusion was incorrect. Half a century later, R. A. Fisher made use of the Galton-Watson process to determine the extinction probability of the progeny of a mutant gene. However, it was J. B. S. Haldane who finally gave the first sketch of the correct conclusion. J. B. S. Haldane also predicted that mathematical genetics might some day develop into a "respectable branch of applied mathematics" (quoted in M. Kimura & T. Ohta, Theoretical Aspects of Population Genetics. Princeton, 1971). Since the time of Fisher and Haldane, the two fields of branching processes and mathematical genetics have attained a high degree of sophistication but in different directions. This monograph is a first attempt to apply the current sta...

  14. Guiding the Giant

    Science.gov (United States)

    1998-08-01

    New ESO Survey Provides Targets for the VLT Giant astronomical telescopes like the ESO Very Large Telescope (VLT) must be used efficiently. Observing time is expensive and there are long waiting lines of excellent research programmes. Thus the work at the telescope must be very well prepared and optimized as much as possible - mistakes should be avoided and no time lost! Astronomers working with the new 8-m class optical/infrared telescopes must base their observations on detailed lists of suitable target objects if they want to perform cutting-edge science. This is particularly true for research programmes that depend on observations of large samples of comparatively rare, distant objects. This type of work requires that extensive catalogues of such objects must be prepared in advance. One such major catalogue - that will serve as a very useful basis for future VLT observations - has just become available from the new ESO Imaging Survey (EIS). The Need for Sky Surveys Astronomers have since long recognized the need to carry out preparatory observations with other telescopes in order to "guide" large telescopes. To this end, surveys of smaller or larger parts of the sky have been performed by wide-field telescopes, paving the way for subsequent work at the limits of the largest available ground-based telescopes. For instance, a complete photographic survey of the sourthern sky (declination deep imaging surveys have thus become an indispensable complement to the 8-m telescopes. The new generation of imaging surveys will, without doubt, be the backbone of future research and are likely to be as long-lived as their earlier counterparts, which have served the astronomical community so well over the past decades. The new surveys are now becoming possible, thanks to the new, extremely light-sensitive CCD-mosaics mounted on wide-field telescopes. The ESO Imaging Survey (EIS) A very successful, major step in this direction has recently been taken at ESO. It concerns an

  15. Electrodynamics in Giant Planet Atmospheres

    Science.gov (United States)

    Koskinen, T.; Yelle, R. V.; Lavvas, P.; Cho, J.

    2014-12-01

    The atmospheres of close-in extrasolar giant planets such as HD209458b are strongly ionized by the UV flux of their host stars. We show that photoionization on such planets creates a dayside ionosphere that extends from the thermosphere to the 100 mbar level. The resulting peak electron density near the 1 mbar level is higher than that encountered in any planetary ionosphere of the solar system, and the model conductivity is in fact comparable to the atmospheres of Sun-like stars. As a result, the momentum and energy balance in the upper atmosphere of HD209458b and similar planets can be strongly affected by ion drag and resistive heating arising from wind-driven electrodynamics. Despite much weaker ionization, electrodynamics is nevertheless also important on the giant planets of the solar system. We use a generic framework to constrain the conductivity regimes on close-in extrasolar planets, and compare the results with conductivites based on the same approach for Jupiter and Saturn. By using a generalized Ohm's law and assumed magnetic fields, we then demonstrate the basic effects of wind-driven ion drag in giant planet atmospheres. Our results show that ion drag is often significant in the upper atmosphere where it can also substantially alter the energy budget through resistive heating.

  16. Observed Properties of Giant Cells

    Science.gov (United States)

    Hathaway, David H.; Upton, Lisa; Colegrove, Owen

    2014-01-01

    The existence of Giant Cells has been suggested by both theory and observation for over 45 years. We have tracked the motions of supergranules in SDO/HMI Doppler velocity data and find larger (Giant Cell) flows that persist for months. The flows in these cells are clockwise around centers of divergence in the north and counter-clockwise in the south. Equatorward flows are correlated with prograde flows - giving the transport of angular momentum toward the equator that is needed to maintain the Sun's rapid equatorial rotation. The cells are most pronounced at mid- and high-latitudes where they exhibit the rotation rates representative of those latitudes. These are clearly large, long-lived, cellular features, with the dynamical characteristics expected from the effects of the Sun's rotation, but the shapes of the cells are not well represented in numerical models. While the Giant Cell flow velocities are small (<10 m/s), their long lifetimes should nonetheless substantially impact the transport of magnetic flux in the Sun's near surface layers.

  17. KEPLER RAPIDLY ROTATING GIANT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A. D.; Martins, B. L. Canto; Bravo, J. P.; Paz-Chinchón, F.; Chagas, M. L. das; Leão, I. C.; Oliveira, G. Pereira de; Silva, R. Rodrigues da; Roque, S.; Oliveira, L. L. A. de; Silva, D. Freire da; De Medeiros, J. R., E-mail: renan@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitário, Natal RN (Brazil)

    2015-07-10

    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of substellar companions by their hosting stars. In the present Letter, we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time, the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting a very short rotation period with values ranging from 13 to 55 days. This finding points to remarkable surface rotation rates, up to 18 times the rotation of the Sun. These giants are combined with six others recently listed in the literature for mid-infrared (IR) diagnostics based on Wide-field Infrared Survey Explorer information, from which a trend for an IR excess is revealed for at least one-half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  18. Kepler rapidly rotating giant stars

    CERN Document Server

    Costa, A D; Bravo, J P; Paz-Chinchón, F; Chagas, M L das; Leão, I C; de Oliveira, G Pereira; da Silva, R Rodrigues; Roque, S; de Oliveira, L L A; da Silva, D Freire; De Medeiros, J R

    2015-01-01

    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of sub-stellar companions by their hosting stars. In the present letter we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting very short rotation period with values ranging from 13 to 55 days. This finding points for remarkable surface rotation rates, up to 18 times the Sun rotation. These giants are combined with 6 other recently listed in the literature for mid-IR diagnostic based on WISE information, from which a trend for an infrared excess is revealed for at least a half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  19. Mechanical properties of branched actin filaments

    CERN Document Server

    Razbin, Mohammadhosein; Benetatos, Panayotis; Zippelius, Annette

    2015-01-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measur...

  20. Is mass loss from red giant stars dust driven?

    Science.gov (United States)

    Yates, J. A.

    1992-12-01

    Long period variable stars on the Asymptotic Giant Branch are observed to be losing mass in the form of cool dusty molecular stellar winds at rates from 10-7 to 10-4 Msunyr-1. The driving force for this mass loss is thought to be radiation pressure on dust particles. The dust transfers its momentum to gas molecules via collisions. This paper discusses the existing evidence for this scenario. New results, from analysis of 22 GHz H2O maser observations made by Merlin, show that the cruical acceleration past the stellar escape velocity of the central star takes place in the inner circumstellar envelope around the central star. The analysis of the velocity fields of the circumstellar envelopes of VX Sgr and VY CMa using the model described by Chapman and Cohen (1986) are discussed.

  1. Rapid Formation of Ice Giant Planets

    CERN Document Server

    Boss, A P; Haghighipour, N; Boss, Alan P.; Wetherill, George W.; Haghighipour, Nader

    2002-01-01

    The existence of Uranus and Neptune presents severe difficulties for the core accretion model for the formation of ice giant planets. We suggest an alternative mechanism, namely disk instability leading to the formation of gas giant protoplanets, coagulation and settling of dust grains to form ice/rock cores at their centers, and photoevaporation of their gaseous envelopes by a nearby OB star, as a possible means of forming ice giant planets.

  2. Solitary ulcerated congenital giant juvenile xanthogranuloma

    Directory of Open Access Journals (Sweden)

    Su Yuen Ng

    2015-01-01

    Full Text Available A 3-month-old female patient with a giant ulcerated nodule over the back since birth was diagnosed as congenital giant juvenile xanthogranuloma (JXG based on clinical and histopathological examination. Congenital giant JXG with ulceration at birth is a rare presentation of JXG and commonly misdiagnosed. This case emphasizes the importance of being aware of the myriad presentations of JXG in order to make a correct diagnosis and avoid unnecessary investigations or treatment.

  3. Exploring masses and CNO surface abundances of red giant stars

    Science.gov (United States)

    Halabi, Ghina M.; Eid, Mounib El

    2015-08-01

    A grid of evolutionary sequences of stars in the mass range 1.2-7M⊙, with solar-like initial composition is presented. We focus on this mass range in order to estimate the masses and calculate the CNO surface abundances of a sample of observed red giants. The stellar models are calculated from the zero-age main sequence till the early asymptotic giant branch (AGB) phase. Stars of M ≤ 2.2M⊙ are evolved through the core helium flash. In this work, an approach is adopted that improves the mass determination of an observed sample of 21 RGB and early AGB stars. This approach is based on comparing the observationally derived effective temperatures and absolute magnitudes with the calculated values based on our evolutionary tracks in the Hertzsprung-Russell diagram. A more reliable determination of the stellar masses is achieved by using evolutionary tracks extended to the range of observation. In addition, the predicted CNO surface abundances are compared to the observationally inferred values in order to show how far standard evolutionary calculation can be used to interpret available observations and to illustrate the role of convective mixing. We find that extra mixing beyond the convective boundary determined by the Schwarzschild criterion is needed to explain the observational oxygen isotopic ratios in low-mass stars. The effect of recent determinations of proton capture reactions and their uncertainties on the 16O/17O and 14N/15N ratios is also shown. It is found that the 14N( p, γ)15O reaction is important for predicting the 14N/15N ratio in red giants.

  4. Determining Ages of APOGEE Giants with Known Distances

    Science.gov (United States)

    Feuillet, Diane K.; Bovy, Jo; Holtzman, Jon; Girardi, Léo; MacDonald, Nick; Majewski, Steven R.; Nidever, David L.

    2016-01-01

    We present a sample of 705 local giant stars observed using the New Mexico State University 1 m telescope with the Sloan Digital Sky Survey-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectrograph, for which we estimate stellar ages and the local star formation history (SFH). The high-resolution (R ˜ 22,500), near infrared (1.51-1.7 μm) APOGEE spectra provide measurements of stellar atmospheric parameters (temperature, surface gravity, [M/H], and [α/M]). Due to the smaller uncertainties in surface gravity possible with high-resolution spectra and accurate Hipparcos distance measurements, we are able to calculate the stellar masses to within 30%. For giants, the relatively rapid evolution up the red giant branch allows the age to be constrained by the mass. We examine methods of estimating age using both the mass-age relation directly and a Bayesian isochrone matching of measured parameters, assuming a constant SFH. To improve the SFH prior, we use a hierarchical modeling approach to constrain the parameters of the model SFH using the age probability distribution functions of the data. The results of an α-dependent Gaussian SFH model show a clear age-[α/M] relation at all ages. Using this SFH model as the prior for an empirical Bayesian analysis, we determine ages for individual stars. The resulting age-metallicity relation is flat, with a slight decrease in [M/H] at the oldest ages and a ˜0.5 dex spread in metallicity across most ages. For stars with ages ≲1 Gyr we find a smaller spread, consistent with radial migration having a smaller effect on these young stars than on the older stars.

  5. DETERMINING AGES OF APOGEE GIANTS WITH KNOWN DISTANCES

    Energy Technology Data Exchange (ETDEWEB)

    Feuillet, Diane K.; Holtzman, Jon [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Bovy, Jo [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Girardi, Léo [Osservatorio Astronomico di Padova—INAF, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); MacDonald, Nick [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Nidever, David L., E-mail: feuilldk@nmsu.edu [Large Synoptic Survey Telescope, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2016-01-20

    We present a sample of 705 local giant stars observed using the New Mexico State University 1 m telescope with the Sloan Digital Sky Survey-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectrograph, for which we estimate stellar ages and the local star formation history (SFH). The high-resolution (R ∼ 22,500), near infrared (1.51–1.7 μm) APOGEE spectra provide measurements of stellar atmospheric parameters (temperature, surface gravity, [M/H], and [α/M]). Due to the smaller uncertainties in surface gravity possible with high-resolution spectra and accurate Hipparcos distance measurements, we are able to calculate the stellar masses to within 30%. For giants, the relatively rapid evolution up the red giant branch allows the age to be constrained by the mass. We examine methods of estimating age using both the mass–age relation directly and a Bayesian isochrone matching of measured parameters, assuming a constant SFH. To improve the SFH prior, we use a hierarchical modeling approach to constrain the parameters of the model SFH using the age probability distribution functions of the data. The results of an α-dependent Gaussian SFH model show a clear age–[α/M] relation at all ages. Using this SFH model as the prior for an empirical Bayesian analysis, we determine ages for individual stars. The resulting age–metallicity relation is flat, with a slight decrease in [M/H] at the oldest ages and a ∼0.5 dex spread in metallicity across most ages. For stars with ages ≲1 Gyr we find a smaller spread, consistent with radial migration having a smaller effect on these young stars than on the older stars.

  6. Telocytes in pancreas of the Chinese giant salamander (Andrias davidianus).

    Science.gov (United States)

    Zhang, Hui; Yu, Pengcheng; Zhong, Shengwei; Ge, Tingting; Peng, Shasha; Guo, Xiaoquan; Zhou, Zuohong

    2016-11-01

    Telocytes (TCs), novel interstitial cells, have been identified in various organs of many mammals. However, information about TCs of lower animals remains rare. Herein, pancreatic TCs of the Chinese giant salamanders (Andrias davidianus) were identified by CD34 immunohistochemistry (IHC) and transmission electron microscopy (TEM). The IHC micrographs revealed CD34(+) TCs with long telopodes (Tps) that were located in the interstitium of the pancreas. CD34(+) TCs/Tps were frequently observed between exocrine acinar cells and were close to blood vessels. The TEM micrographs also showed the existence of TCs in the interstitium of the pancreas. TCs had distinctive ultrastructural features, such as one to three very long and thin Tps with podoms and podomers, caveolae, dichotomous branching, neighbouring exosomes and vesicles. The Tps and exosomes were found in close proximity to exocrine acinar cells and α cells. It is suggested that TCs may play a role in the regeneration of acinar cells and α cells. In conclusion, our results demonstrated the presence of TCs in the pancreas of the Chinese giant salamander. This finding will assist us in a better understanding of TCs functions in the amphibian pancreas. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  7. Exploring masses and CNO surface abundances of red giant stars

    CERN Document Server

    Halabi, Ghina M

    2015-01-01

    A grid of evolutionary sequences of stars in the mass range $1.2$-$7$ M$_{\\odot}$, with solar-like initial composition is presented. We focus on this mass range in order to estimate the masses and calculate the CNO surface abundances of a sample of observed red giants. The stellar models are calculated from the zero-age main sequence till the early asymptotic giant branch (AGB) phase. Stars of M $\\leqslant$ $2.2$M$_{\\odot}$ are evolved through the core helium flash. In this work, an approach is adopted that improves the mass determination of an observed sample of 21 RGB and early AGB stars. This approach is based on comparing the observationally derived effective temperatures and absolute magnitudes with the calculated values based on our evolutionary tracks in the Hertzsprung-Russell diagram. A more reliable determination of the stellar masses is achieved by using evolutionary tracks extended to the range of observation. In addition, the predicted CNO surface abundances are compared to the observationally in...

  8. RADIO EMISSION FROM RED-GIANT HOT JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Yuka [Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, 152-8550 (Japan); Spiegel, David S. [Analytics and Algorithms, Stitch Fix, San Francisco, CA 94103 (United States); Mroczkowski, Tony [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (United States); Nordhaus, Jason [Department of Science and Mathematics, National Technical Institute for the Deaf, Rochester Institute of Technology, Rochester, NY 14623 (United States); Zimmerman, Neil T. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Parsons, Aaron R. [Astronomy Department, University of California, Berkeley, CA (United States); Mirbabayi, Mehrdad [Astrophysics Department, Institute for Advanced Study, Princeton, NJ 08540 (United States); Madhusudhan, Nikku, E-mail: yuka.fujii@elsi.jp [Astronomy Department, University of Cambridge (United Kingdom)

    2016-04-01

    When planet-hosting stars evolve off the main sequence and go through the red-giant branch, the stars become orders of magnitudes more luminous and, at the same time, lose mass at much higher rates than their main-sequence counterparts. Accordingly, if planetary companions exist around these stars at orbital distances of a few au, they will be heated up to the level of canonical hot Jupiters and also be subjected to a dense stellar wind. Given that magnetized planets interacting with stellar winds emit radio waves, such “Red-Giant Hot Jupiters” (RGHJs) may also be candidate radio emitters. We estimate the spectral auroral radio intensity of RGHJs based on the empirical relation with the stellar wind as well as a proposed scaling for planetary magnetic fields. RGHJs might be intrinsically as bright as or brighter than canonical hot Jupiters and about 100 times brighter than equivalent objects around main-sequence stars. We examine the capabilities of low-frequency radio observatories to detect this emission and find that the signal from an RGHJ may be detectable at distances up to a few hundred parsecs with the Square Kilometer Array.

  9. The dust condensation sequence in red super-giant stars

    CERN Document Server

    Verhoelst, T; Hony, S; Decin, L; Cami, J; Eriksson, K

    2009-01-01

    Context: Red super-giant (RSG) stars exhibit significant mass loss through a slow and dense wind. They are often considered to be the more massive counter parts of Asymptotic Giant Branch (AGB) stars. While the AGB mass loss is linked to their strong pulsations, the RSG are often only weakly variable. Aim: To study the conditions at the base of the wind, by determining the dust composition in a sample of RSG. The dust composition is thought to be sensitive to the density, temperature and acceleration at the base of the wind. Method: We compile a sample of 27 RSG infrared spectra (ISO-SWS) and supplement these with photometric measurements to obtain the full spectral energy distribution (SED). These data are modelled using a dust radiative transfer code. The results are scrutinised for correlations. Results: We find (1) strong correlations between dust composition, mass-loss rate and stellar luminosity, roughly in agreement with the theoretical dust condensation sequence, (2) the need for a continuous (near-)I...

  10. Transmission Electron Microscopy of Al-rich Silicate Stardust from Asymptotic Giant Branch Stars

    Science.gov (United States)

    Vollmer, Christian; Hoppe, Peter; Brenker, Frank E.

    2013-05-01

    We report on transmission electron microscopy (TEM) investigations of two mineralogically unusual stardust silicates to constrain their circumstellar condensation conditions. Both grains were identified by high spatial resolution nano secondary ion mass spectrometry (NanoSIMS) in the Acfer 094 meteorite, one of the most pristine carbonaceous chondrites available for study. One grain is a highly crystalline, highly refractory (Fe content formation of olivine over pyroxene is favored in circumstellar environments, in agreement with expectations from condensation theory and experiments. The second stardust silicate consists of an amorphous Ca-Si rich material which lacks any crystallinity based on TEM observations in which tiny (<20 nm) hibonite nanocrystallites are embedded. This complex assemblage therefore attests to the fast cooling and rapidly changing chemical environments under which dust grains in circumstellar shells form.

  11. TRANSMISSION ELECTRON MICROSCOPY OF Al-RICH SILICATE STARDUST FROM ASYMPTOTIC GIANT BRANCH STARS

    Energy Technology Data Exchange (ETDEWEB)

    Vollmer, Christian [Institute for Mineralogy, University of Muenster, Correnssstr. 24, D-48149 Muenster (Germany); Hoppe, Peter [Max Planck Institute for Chemistry, Particle Chemistry Department, Hahn-Meitner-Weg 1, D-55128 Mainz (Germany); Brenker, Frank E., E-mail: christian.vollmer@wwu.de [Institute of Geoscience/Mineralogy, Goethe-University Frankfurt, Altenhoeferallee 1, D-60438 Frankfurt (Germany)

    2013-05-20

    We report on transmission electron microscopy (TEM) investigations of two mineralogically unusual stardust silicates to constrain their circumstellar condensation conditions. Both grains were identified by high spatial resolution nano secondary ion mass spectrometry (NanoSIMS) in the Acfer 094 meteorite, one of the most pristine carbonaceous chondrites available for study. One grain is a highly crystalline, highly refractory (Fe content < 0.5 at%), structurally undisturbed orthopyroxene (MgSiO{sub 3}) with an unusually high Al content (1.8 {+-} 0.5 at%). This is the first TEM documentation of a single crystal pyroxene within the complete stardust silicate data set. We interpret the microstructure and chemistry of this grain as being a direct condensate from a gas of locally non-solar composition (i.e., with a higher-than-solar Al content and most likely also a lower-than-solar Mg/Si ratio) at (near)-equilibrium conditions. From the overabundance of crystalline olivine (six reported grains to date) compared to crystalline pyroxene (only documented as a single crystal in this work) we infer that formation of olivine over pyroxene is favored in circumstellar environments, in agreement with expectations from condensation theory and experiments. The second stardust silicate consists of an amorphous Ca-Si rich material which lacks any crystallinity based on TEM observations in which tiny (<20 nm) hibonite nanocrystallites are embedded. This complex assemblage therefore attests to the fast cooling and rapidly changing chemical environments under which dust grains in circumstellar shells form.

  12. VLA Observations of HI in the Circumstellar Envelopes of Asymptotic Giant Branch Stars

    CERN Document Server

    Matthews, Lynn D; 10.1086/512613

    2008-01-01

    (Abridged) We have used the VLA to search for neutral atomic hydrogen in the circumstellar envelopes of five AGB stars. We have detected HI 21-cm emission coincident in both position and velocity with the semi-regular variable RS Cnc. The emission comprises a compact, slightly elongated feature centered on the star with a mean diameter ~82'' (1.5e17 cm), plus an additional filament extending ~6' to the NW. This filament suggests that a portion of the mass loss is highly asymmetric. We estimate MHI=1.5e-3 Msun and M_dot~1.7e-7 Msun/yr. Toward R Cas, we detect weak emission that peaks at the stellar systemic velocity and overlaps with the location of its circumstellar dust shell and thus is probably related to the star. In the case of IRC+10216, we were unable to confirm the detection of HI in absorption against the cosmic background previously reported by Le Bertre & Gerard. However, we detect arcs of emission at projected distances of r~14'-18' (~2e18 cm) to the NW. A large separation of the emission from...

  13. Binarity in Cool Asymptotic Giant Branch Stars: A Galex Search for Ultraviolet Excesse

    CERN Document Server

    Sahai, R; de Paz, A Gil; Contreras, C Sánchez

    2008-01-01

    The search for binarity in AGB stars is of critical importance for our understanding of how planetary nebulae acquire the dazzling variety of aspherical shapes which characterises this class. However, detecting binary companions in such stars has been severely hampered due to their extreme luminosities and pulsations. We have carried out a small imaging survey of AGB stars in ultraviolet light (using GALEX) where these cool objects are very faint, in order to search for hotter companions. We report the discovery of significant far-ultraviolet excesses towards nine of these stars. The far-ultraviolet excess most likely results either directly from the presence of a hot binary companion, or indirectly from a hot accretion disk around the companion.

  14. Mixing along the Red Giant Branch in Metal-poor Field Stars

    CERN Document Server

    Carretta, E; Sneden, C; Bragaglia, A; Carretta, Eugenio; Gratton, Raffaele; Sneden, Chris; Bragaglia, Angela

    1999-01-01

    We have determined Li, C, N, O, Na, and Fe abundances, and 12C/13C isotopic ratios for a sample of 62 field metal-poor stars (plus 43 taken from the literature). This large sample was used to show that small mass lower-RGB stars (i.e., fainter than the RGB bump) have abundances of light elements in agreement with theoretical predictions from classical evolutionary models. A second, distinct mixing episode occurs just after the RGB bump, reaching regions of incomplete CNO burning. No O-Na anticorrelation, as observed in globular cluster stars, is found in field stars. This means that the mixing episode is not deep enough to reach regions where ON-burning occurs.

  15. Determining the forsterite abundance of the dust around Asymptotic Giant Branch stars

    CERN Document Server

    de Vries, B L; Waters, L B F M; Blommaert, J A D L; Kemper, F

    2010-01-01

    Aims. We present a diagnostic tool to determine the abundance of the crystalline silicate forsterite in AGB stars surrounded by a thick shell of silicate dust. Using six infrared spectra of high mass-loss oxygen rich AGB stars we obtain the forsterite abundance of their dust shells. Methods. We use a monte carlo radiative transfer code to calculate infrared spectra of dust enshrouded AGB stars. We vary the dust composition, mass-loss rate and outer radius. We focus on the strength of the 11.3 and the 33.6 \\mu m forsterite bands, that probe the most recent (11.3 \\mu m) and older (33.6 \\mu m) mass-loss history of the star. Simple diagnostic diagrams are derived, allowing direct comparison to observed band strengths. Results. Our analysis shows that the 11.3 \\mu m forsterite band is a robust indicator for the forsterite abundance of the current mass-loss period for AGB stars with an optically thick dust shell. The 33.6 \\mu m band of forsterite is sensitive to changes in the density and the geometry of the emitti...

  16. Condensation of refractory metals in asymptotic giant branch and other stellar environments

    Energy Technology Data Exchange (ETDEWEB)

    Schwander, D.; Berg, T.; Schönhense, G.; Ott, U., E-mail: schwandd@uni-mainz.de [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55128 Mainz (Germany)

    2014-09-20

    The condensation of material from a gas of solar composition has been extensively studied, but less so condensation in the environment of evolved stars, which has been mainly restricted to major compounds and some specific element groups such as the Rare Earth elements. Also of interest, however, are refractory metals like Mo, Ru, Os, W, Ir, and Pt, which may condense to form refractory metal nuggets (RMNs) like the ones that have been found in association with presolar graphite. We have performed calculations describing the condensation of these elements in the outflows of s-process enriched AGB stars as well as from gas enriched in r-process products. While in carbon-rich environments (C > O), the formation of carbides is expected to consume W, Mo, and V (Lodders and Fegley), the condensation sequence for the other refractory metals under these conditions does not significantly differ from the case of a cooling gas of solar composition. The composition in detail, however, is significantly different due to the completely different source composition. Condensation from an r-process enriched source differs less from the solar case. Elemental abundance ratios of the refractory metals can serve as a guide for finding candidate presolar grains among the RMNs in primitive meteorites—most of which have a solar system origin—for confirmation by isotopic analysis. We apply our calculations to the case of the four RMNs found by Croat et al., which may very well be presolar.

  17. Evolution of Thermally Pulsing Asymptotic Giant Branch Stars I. The COLIBRI Code

    CERN Document Server

    Marigo, Paola; Nanni, Ambra; Girardi, Leo; Pumo, Maria Letizia

    2013-01-01

    We present the COLIBRI code for computing the evolution of stars along the TP-AGB phase. Compared to purely synthetic TP-AGB codes, COLIBRI relaxes a significant part of their analytic formalism in favour of a detailed physics applied to a complete envelope model, in which the stellar structure equations are integrated from the atmosphere down to the bottom of the hydrogen-burning shell. This allows to predict self-consistently: (i) the effective temperature, and more generally the convective envelope and atmosphere structures, correctly coupled to the changes in the surface chemical abundances and gas opacities; (ii) sphericity effects in the atmospheres; (iii) the core mass-luminosity relation and its break-down due to hot bottom burning (HBB) in the most massive AGB stars, (iv) the HBB nucleosynthesis via the solution of a complete nuclear network (pp chains, and the CNO, NeNa, MgAl cycles), including also the production of 7Li via the Cameron-Fowler beryllium transport mechanism; (v) the chemical composit...

  18. Mass loss from red giants - A simple evolutionary model for NGC 7027

    Science.gov (United States)

    Jura, M.

    1984-01-01

    NGC 7027 is a young planetary nebula with the remnants of a red giant circumstellar envelope surrounding the central, ionized region. By comparing the outer molecular envelope with the inner ionized material, it is argued that the mass loss rate has decreased by at least a factor of 3, and more probably by about a factor of 10, during the past 1000 years. From this result, it is argued that the luminosity of the central star has also decreased substantially during the same time, consistent with models for the rapid evolution of stars just after they evolve off the asymptotic giant branch. In this picture, the distance to NGC 7027 is less than 1300 pc. NGC 7027 was the last (and best) example of a star where apparently the momentum in the outflowing mass /M(dot)v/ is considerably greater than the momentum in the radiation field (L/c). With the above description of this object, the evidence is now strong that quite often the mass lost from late-type giants is ultimately driven to infinity by radiation pressure on grains. If M(dot)v is as large as L/c for asymptotic branch stars, then it is expected that the total amount of mass lost during this stage of evolution is of the same magnitude as the initial mass of the star, and therefore this mass loss can profoundly affect the star's ultimate fate.

  19. Mass loss from red giants - A simple evolutionary model for NGC 7027

    Science.gov (United States)

    Jura, M.

    1984-01-01

    NGC 7027 is a young planetary nebula with the remnants of a red giant circumstellar envelope surrounding the central, ionized region. By comparing the outer molecular envelope with the inner ionized material, it is argued that the mass loss rate has decreased by at least a factor of 3, and more probably by about a factor of 10, during the past 1000 years. From this result, it is argued that the luminosity of the central star has also decreased substantially during the same time, consistent with models for the rapid evolution of stars just after they evolve off the asymptotic giant branch. In this picture, the distance to NGC 7027 is less than 1300 pc. NGC 7027 was the last (and best) example of a star where apparently the momentum in the outflowing mass /M(dot)v/ is considerably greater than the momentum in the radiation field (L/c). With the above description of this object, the evidence is now strong that quite often the mass lost from late-type giants is ultimately driven to infinity by radiation pressure on grains. If M(dot)v is as large as L/c for asymptotic branch stars, then it is expected that the total amount of mass lost during this stage of evolution is of the same magnitude as the initial mass of the star, and therefore this mass loss can profoundly affect the star's ultimate fate.

  20. The Gaia-ESO Survey: Inhibited extra mixing in two giants of the open cluster Trumpler 20?

    Science.gov (United States)

    Smiljanic, R.; Franciosini, E.; Randich, S.; Magrini, L.; Bragaglia, A.; Pasquini, L.; Vallenari, A.; Tautvaišienė, G.; Biazzo, K.; Frasca, A.; Donati, P.; Delgado Mena, E.; Casey, A. R.; Geisler, D.; Villanova, S.; Tang, B.; Sousa, S. G.; Gilmore, G.; Bensby, T.; François, P.; Koposov, S. E.; Lanzafame, A. C.; Pancino, E.; Recio-Blanco, A.; Costado, M. T.; Hourihane, A.; Lardo, C.; de Laverny, P.; Lewis, J.; Monaco, L.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.; Zaggia, S.; Martell, S.

    2016-06-01

    Aims: We report the discovery of two Li-rich giants, with A(Li) ~ 1.50, in an analysis of a sample of 40 giants of the open cluster Trumpler 20 (with turnoff mass ~1.8 M⊙). The cluster was observed in the context of the Gaia-ESO Survey. Methods: The atmospheric parameters and Li abundances were derived using high-resolution UVES spectra. The Li abundances were corrected for nonlocal thermodynamical equilibrium (non-LTE) effects. Results: Only upper limits of the Li abundance could be determined for the majority of the sample. Two giants with detected Li turned out to be Li rich: star MG 340 has A(Li)non-LTE = 1.54 ± 0.21 dex and star MG 591 has A(Li)non-LTE = 1.60 ± 0.21 dex. Star MG 340 is on average ~0.30 dex more rich in Li than stars of similar temperature, while for star MG 591 this difference is on average ~0.80 dex. Carbon and nitrogen abundances indicate that all stars in the sample have completed the first dredge-up. Conclusions: The Li abundances in this unique sample of 40 giants in one open cluster clearly show that extra mixing is the norm in this mass range. Giants with Li abundances in agreement with the predictions of standard models are the exception. To explain the two Li-rich giants, we suggest that all events of extra mixing have been inhibited. This includes rotation-induced mixing during the main sequence and the extra mixing at the red giant branch luminosity bump. Such inhibition has been suggested in the literature to occur because of fossil magnetic fields in red giants that are descendants of main-sequence Ap-type stars. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey).

  1. Membership, binarity and metallicity of red giants in the southern open cluster NGC 2354

    Science.gov (United States)

    Clariá, J. J.; Mermilliod, J.-C.; Piatti, A. E.

    1999-01-01

    We present new Coravel radial-velocity observations and photoelectric photometry in the UBV, DDO and Washington systems for a sample of red giant candidates in the field of the intermediate-age open cluster NGC 2354. Photometric membership probabilities show very good agreement with those obtained from Coravel radial velocities. The analysis of the photometric and kinematical data allow us to confirm cluster membership for 9 red giants, one of them being a spectroscopic binary, while 4 confirmed spectroscopic binaries appear to be probable members. We have also discovered 4 spectroscopic binaries not belonging to the cluster. A mean radial velocity of (33.40 +/- 0.27) km s(-1) and a mean reddening E(B-V) = 0.13 +/- 0.03 were derived for the cluster giants. NGC 2354 has a mean ultraviolet excess B)> = -0.03 +/- 0.01, relative to the field K giants, and a mean new cyanogen anomaly Delta CN = -0.035 +/- 0.007, both implying [Fe/H] ~ -0.3. The moderately metal-poor character of NGC 2354 is confirmed using five different metal abundance indicators of the Washington system. The cluster giant branch is formed by a well defined clump of 7 stars and 4 stars with high membership probabilities seem to define an ascending giant branch. The whole red giant locus cannot be reproduced by any theoretical track. Based on observations collected with the Danish\\protect\\linebreak 1.54-m telescope at the European Southern Observatory, La Silla (Chile); at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan, Argentina, and at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.

  2. Chiral methyl-branched pheromones.

    Science.gov (United States)

    Ando, Tetsu; Yamakawa, Rei

    2015-07-01

    Insect pheromones are some of the most interesting natural products because they are utilized for interspecific communication between various insects, such as beetles, moths, ants, and cockroaches. A large number of compounds of many kinds have been identified as pheromone components, reflecting the diversity of insect species. While this review deals only with chiral methyl-branched pheromones, the chemical structures of more than one hundred non-terpene compounds have been determined by applying excellent analytical techniques. Furthermore, their stereoselective syntheses have been achieved by employing trustworthy chiral sources and ingenious enantioselective reactions. The information has been reviewed here not only to make them available for new research but also to understand the characteristic chemical structures of the chiral pheromones. Since biosynthetic studies are still limited, it might be meaningful to examine whether the structures, particularly the positions and configurations of the branched methyl groups, are correlated with the taxonomy of the pheromone producers and also with the function of the pheromones in communication systems.

  3. Surgical management of large and giant intracavernous and paraclinoid aneurysms

    Institute of Scientific and Technical Information of China (English)

    Xu Bai-nan; SUN Zheng-hui; JIANG Jin-li; WU Chen; ZHOU Ding-biao; YU Xin-guang; LI Bao-min

    2008-01-01

    Background Due to their location,large and giant intracavernous and paraclinoid aneurysms remain a challenge for vascular neurosurgeons.We identified characteristics.surgical indications and treatment strategies of large and giant intracavernous and paraclinoid aneurysms in 36 patients.Methods The pterional approach was routinely used.The cervical internal carotid artery was exposed for proximal control of parent vessel and retrograde suction decompression.Paraclinoid aneurysms were directly clipped,intracavernous pseudoaneurysm was repaired and the intracavernous aneurysms were trapped with extracranial-intracranial bypass of saphenous vein graft.Intraoperative electroencephaIogram (EEG) and somatosensory evoked potential (SSEP) monitoring were used to detect cerebral ischemia during the temporary occlusion of parent arteries.Microvascular Doppler ultrasonography was used to assess blood flow of the parent and branch vessels.Endoscopy was helpful particularly in dealing with internal carotid artery posterior wall aneurysms.Postoperative digital subtraction angiography (DSA) was performed in 33 of the 36 patients.Results Thirty-two paraclinoid aneurysms were directly clipped,1 intracavernous pseudoaneurysm was repaired and the other 3 intracavernous aneurysms were trapped with revascula rization.Except for two patients who died in the early postoperative stage,34 patients' follow-up was 6-65 months (mean 10 months)and a Glasgow Outcome Scale score of 4 to 5 at discharge.At the 6-month follow-up examination,Rankin Outcome Scale scores were 0 to 2 in 32 patients.EEG and SSEP monitoring changed in six patients.Twelve clips were readjusted when insufficient blood flow in parent and branch vessels was detected.Three posterior wall aneurysms were clipped.Conclusions Intracavernous aneurysms not amenable to endovascular treatment should be treated surgically and surgical treatment is the first option for paraclinoid aneurysms.The temporary parent vessel occlusion

  4. Giant magneto-resistance devices

    CERN Document Server

    Hirota, Eiichi; Inomata, Koichiro

    2002-01-01

    This book deals with the application of giant magneto-resistance (GMR) effects to electronic devices. It will appeal to engineers and graduate students in the fields of electronic devices and materials. The main subjects are magnetic sensors with high resolution and magnetic read heads with high sensitivity, required for hard-disk drives with recording densities of several gigabytes. Another important subject is novel magnetic random-access memories (MRAM) with non-volatile non-destructive and radiation-resistant characteristics. Other topics include future GMR devices based on bipolar spin transistors, spin field-effect transistors (FETs) and double-tunnel junctions.

  5. GIANT OILFIELD DISCOVERED IN BOHAI

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ PetroChina announced a discovery of a giant oilfield in the beginning of May, which has a reserve of one billion tons, or about 7.35 billion barrels, the largest discovery in China over four decades. Of the reserves, the basically proven oil in place is 405 million tons with the average thickness of oil formations ranging between 80 meters and 100 meters. The oilfield lies in the Nanpu block of PetroChina Jidong Oilfield Company in Caofeidian industrial zone, north China's Hebei province. The area is expected to enjoy a better chance of becoming a national oil strategic reserve base following the discovery of the Nanpu Oilfield.

  6. On the Shoulders of Giants...

    Science.gov (United States)

    2013-01-01

    On the shoulders of giantsI Basil A. Pruitt, Jr., MD and Todd E. Rasmussen, MD I n a letter dated February 5, 1676 (dated 1675 using the Julian...T.E.R.), Fort Sam Houston, San Antonio, TX. Address for reprints: Basil A. Pruitt, Jr, MD, Division of Trauma, Department of Surgery, The University...default.htm. 20. Moore FD. Edward Delos Churchill (1895Y1972). Ann Surg. 1973; 177:507Y508. 21. The Board for the Study of the Severely Wounded. The

  7. Internal rotation of red giants by asteroseismology

    CERN Document Server

    Di Mauro, M P; Ventura, R; Stello, D; Beck, P G; Davies, G; Elsworth, Y; Garcıa, R A; Hekker, S; Mosser, B; Christensen-Dalsgaard, J; Bloemen, S; Catanzaro, G; De Smedt, K; Tkachenko, A

    2012-01-01

    We present an asteroseismic approach to study the dynamics of the stellar interior in red-giant stars by asteroseismic inversion of the splittings induced by the stellar rotation on the oscillation frequencies. We show preliminary results obtained for the red giant KIC4448777 observed by the space mission Kepler.

  8. Giant Rings in the CMB Sky

    CERN Document Server

    Kovetz, Ely D; Itzhaki, Nissan

    2010-01-01

    We find a unique direction in the CMB sky around which giant rings have an anomalous mean temperature profile. This direction is in very close alignment with the afore measured anomalously large bulk flow direction. We argue that a cosmic defect seeded by a pre-inflationary particle could explain the giant rings, the large bulk flow and their alignment.

  9. Totally thrombosed giant anterior communicating artery aneurysm

    Directory of Open Access Journals (Sweden)

    V R Roopesh Kumar

    2015-01-01

    Full Text Available Giant anterior communicating artery aneurysmsarerare. Apatient presented with visual dysfunction, gait ataxia and urinary incontinence. MRI showed a giant suprasellar mass.At surgery, the lesion was identified as being an aneurysm arising from the anterior communicating artery.The difficulty in preoperative diagnosis and relevant literature are reviewed.

  10. Surgical treatment for giant incisional hernia

    DEFF Research Database (Denmark)

    Eriksson, A; Rosenberg, J; Bisgaard, T

    2014-01-01

    INTRODUCTION: Repair for giant incisional hernias is a challenge due to unacceptable high morbidity and recurrence rates. Several surgical techniques are available, but all are poorly documented. This systematic review was undertaken to evaluate the existing literature on repair for giant incisio...... procedure and severely lack evidence-based research from high-quality, large-scaled randomised studies....

  11. Huge aneurysm and coronary-cameral fistula from right coronary branch: First case.

    Science.gov (United States)

    Ahmad, Tanveer; Pasarad, Ashwini Kumar; Kishore, Kolkebaile Sadanand; Maheshwarappa, Nandakumar Neralakere

    2016-02-01

    Coronary-cameral fistulas are rare cardiovascular anomalies. A giant coronary artery aneurysm associated with a coronary-cameral fistula is a very rare condition, with an estimated prevalence of 0.02%. We report the case of middle-aged woman who presented with a huge extracardiac aneurysmal mass and a coronary-cameral fistula from a right coronary artery branch. It was successfully repaired by ligation and excision plus marsupialization of the aneurysm. We believe this is the first such a case reported in literature.

  12. Complex Organic and Inorganic Compounds in Shells of Lithium-rich K Giant Stars

    CERN Document Server

    de la Reza, Ramiro; Oliveira, Isa; Rengaswamy, Sridharan

    2015-01-01

    Hydrocarbon organic material, as found in the interstellar medium, exists in complex mixtures of aromatic and aliphatic forms. It is considered to be originated from carbon enriched giant stars during their final stages of evolution, when very strong mass loss occurs in a few thousand years on their way to become planetary nebulae. We show here that the same organic compounds appear to be formed in previous stages of the evolution of giant stars. More specifically, during the first ascending giant branch K-type stars. According to our model this happens only when these stars are being abruptly enriched with lithium together with the formation of a circumstellar shell with a strong mass loss during just a few thousand years. This sudden mass loss is, on an average, a thousand times larger than that of normal Li-poor K giant stars. This shell would later be detached, specially when the star stops its Li enrichment and a rapid photospheric Li depletion occurs. In order to gain extra carbon-based material to form...

  13. A Catalog of Distance Determinations for the SEGUE K giants in the Galactic Halo

    CERN Document Server

    Xue, Xiang-Xiang; Rix, Hans-Walter; Morrison, Heather L; Harding, Paul; Beers, Timothy C; Ivans, Inese I; Jacobson, Heather R; Johnson, Jennifer; Lee, Young Sun; Lucatello, Sara; Rockosi, Constance M; Sobeck, Jennifer S; Yanny, Brian

    2012-01-01

    We present an online catalog of distance determinations for 4781 K giants, most of which are members of the Milky Way's stellar halo. Their spectra from SDSS/SEGUE provide metallicities with accuracies \\Delta [Fe/H]\\approx\\pm0.2 dex and giant-dwarf distinction. The distance moduli are derived from a comparison of each star's apparent magnitude with the absolute magnitude of empirically calibrated color-luminosity fiducials, at the observed (g-r)_0 color and spectroscopic [Fe/H]. We employ a probabilistic approach that makes it straightforward to propagate the errors in metallicities, magnitudes, and colors properly into distance uncertainties. We also fold in {\\it prior} information about the giant-branch luminosity function and different metallicity distributions of the SEGUE K-giant targeting sub-categories. We show that the metallicity prior plays little role in the distance estimates, but that neglecting the luminosity prior would lead to a systematic distance modulus bias of up to 0.2 mag. We find a medi...

  14. The First Empirical Mass Loss Law for Population II Giants

    CERN Document Server

    Origlia, Livia; Fabbri, Sara; Ferraro, Francesco R; Pecci, Flavio Fusi; Rich, R Michael

    2007-01-01

    Using the Spitzer IRAC camera we have obtained mid-IR photometry of the red giant branch stars in the Galactic globular cluster 47 Tuc. About 100 stars show an excess of mid-infrared light above that expected from their photospheric emission. This is plausibly due to dust formation in mass flowing from these stars. This mass loss extends down to the level of the horizontal branch and increases with luminosity. The mass loss is episodic, occurring in only a fraction of stars at a given luminosity. Using a simple model and our observations we derive mass loss rates for these stars. Finally, we obtain the first empirical mass loss formula calibrated with observations of Population II stars. The dependence on luminosity of our mass loss rate is considerably shallower than the widely used Reimers Law. The results presented here are the first from our Spitzer survey of a carefully chosen sample of 17 Galactic Globular Clusters, spanning the entire metallicity range from about one hundredth up to almost solar.

  15. Giant Planet Formation, Evolution, and Internal Structure

    CERN Document Server

    Helled, Ravit; Podolak, Morris; Boley, Aaron; Meru, Farzana; Nayakshin, Sergei; Fortney, Jonathan J; Mayer, Lucio; Alibert, Yann; Boss, Alan P

    2013-01-01

    The large number of detected giant exoplanets offers the opportunity to improve our understanding of the formation mechanism, evolution, and interior structure of gas giant planets. The two main models for giant planet formation are core accretion and disk instability. There are substantial differences between these formation models, including formation timescale, favorable formation location, ideal disk properties for planetary formation, early evolution, planetary composition, etc. First, we summarize the two models including their substantial differences, advantages, and disadvantages, and suggest how theoretical models should be connected to available (and future) data. We next summarize current knowledge of the internal structures of solar- and extrasolar- giant planets. Finally, we suggest the next steps to be taken in giant planet exploration.

  16. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370

    Science.gov (United States)

    Hrudková, M.; Hatzes, A.; Karjalainen, R.; Lehmann, H.; Hekker, S.; Hartmann, M.; Tkachenko, A.; Prins, S.; Van Winckel, H.; De Nutte, R.; Dumortier, L.; Frémat, Y.; Hensberge, H.; Jorissen, A.; Lampens, P.; Laverick, M.; Lombaert, R.; Pápics, P. I.; Raskin, G.; Sódor, Á.; Thoul, A.; Van Eck, S.; Waelkens, C.

    2017-01-01

    We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 ± 1.0 MJupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our programme to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coudé echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph High Efficiency and Resolution Mercator Echelle Spectrograph of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 ± 4.5 d) variation with a semi-amplitude K = 133 ± 25 m s- 1, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ˜88 yr in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-amplitude radial velocity variations and only future continued monitoring of this system may answer this uncertainty. From Kepler photometry, we find that HD 175370 is most likely a low-mass red giant branch or asymptotic giant branch star.

  17. Branching diffusions in random environment

    CERN Document Server

    Böinghoff, Christian

    2011-01-01

    We consider the diffusion approximation of branching processes in random environment (BPREs). This diffusion approximation is similar to and mathematically more tractable than BPREs. We obtain the exact asymptotic behavior of the survival probability. As in the case of BPREs, there is a phase transition in the subcritical regime due to different survival opportunities. In addition, we characterize the process conditioned to never go extinct and establish a backbone construction. In the strongly subcritical regime, mean offspring numbers are increased but still subcritical in the process conditioned to never go extinct. Here survival is solely due to an immortal individual, whose offspring are the ancestors of additional families. In the weakly subcritical regime, the mean offspring number is supercritical in the process conditioned to never go extinct. Thus this process survives with positive probability even if there was no immortal individual.

  18. Branching process models of cancer

    CERN Document Server

    Durrett, Richard

    2015-01-01

    This volume develops results on continuous time branching processes and applies them to study rate of tumor growth, extending classic work on the Luria-Delbruck distribution. As a consequence, the authors calculate the probability that mutations that confer resistance to treatment are present at detection and quantify the extent of tumor heterogeneity. As applications, the authors evaluate ovarian cancer screening strategies and give rigorous proofs for results of Heano and Michor concerning tumor metastasis. These notes should be accessible to students who are familiar with Poisson processes and continuous time. Richard Durrett is mathematics professor at Duke University, USA. He is the author of 8 books, over 200 journal articles, and has supervised more than 40 Ph.D. students. Most of his current research concerns the applications of probability to biology: ecology, genetics, and most recently cancer.

  19. Stabilization of Branching Queueing Networks

    CERN Document Server

    Brázdil, Tomáš

    2011-01-01

    Queueing networks are gaining attraction for the performance analysis of parallel computer systems. A Jackson network is a set of interconnected servers, where the completion of a job at server i may result in the creation of a new job for server j. We propose to extend Jackson networks by "branching" and by "control" features. Both extensions are new and substantially expand the modelling power of Jackson networks. On the other hand, the extensions raise computational questions, particularly concerning the stability of the networks, i.e, the ergodicity of the underlying Markov chain. We show for our extended model that it is decidable in polynomial time if there exists a controller that achieves stability. Moreover, if such a controller exists, one can efficiently compute a static randomized controller which stabilizes the network in a very strong sense; in particular, all moments of the queue sizes are finite.

  20. The subdwarf B star SB 290 - A fast rotator on the extreme horizontal branch

    CERN Document Server

    Geier, S; Heuser, C; Classen, L; O'Toole, S J; Edelmann, H

    2013-01-01

    Hot subdwarf B stars (sdBs) are evolved core helium-burning stars with very thin hydrogen envelopes. In order to form an sdB, the progenitor has to lose almost all of its hydrogen envelope right at the tip of the red giant branch. In close binary systems, mass transfer to the companion provides the extraordinary mass loss required for their formation. However, apparently single sdBs exist as well and their formation is unclear since decades. The merger of helium white dwarfs leading to an ignition of core helium-burning or the merger of a helium core and a low mass star during the common envelope phase have been proposed. Here we report the discovery of SB 290 as the first apparently single fast rotating sdB star located on the extreme horizontal branch indicating that those stars may form from mergers.

  1. Vegetation survey of PEN Branch wetlands

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    A survey was conducted of vegetation along Pen Branch Creek at Savannah River Site (SRS) in support of K-Reactor restart. Plants were identified to species by overstory, understory, shrub, and groundcover strata. Abundance was also characterized and richness and diversity calculated. Based on woody species basal area, the Pen Branch delta was the most impacted, followed by the sections between the reactor and the delta. Species richness for shrub and groundcover strata were also lowest in the delta. No endangered plant species were found. Three upland pine areas were also sampled. In support of K Reactor restart, this report summarizes a study of the wetland vegetation along Pen Branch. Reactor effluent enters Indian Grove Branch and then flows into Pen Branch and the Pen Branch Delta.

  2. Separating gas-giant and ice-giant planets by halting pebble accretion

    Science.gov (United States)

    Lambrechts, M.; Johansen, A.; Morbidelli, A.

    2014-12-01

    In the solar system giant planets come in two flavours: gas giants (Jupiter and Saturn) with massive gas envelopes, and ice giants (Uranus and Neptune) with much thinner envelopes around their cores. It is poorly understood how these two classes of planets formed. High solid accretion rates, necessary to form the cores of giant planets within the life-time of protoplanetary discs, heat the envelope and prevent rapid gas contraction onto the core, unless accretion is halted. We find that, in fact, accretion of pebbles (~cm sized particles) is self-limiting: when a core becomes massive enough it carves a gap in the pebble disc. This halt in pebble accretion subsequently triggers the rapid collapse of the super-critical gas envelope. Unlike gas giants, ice giants do not reach this threshold mass and can only bind low-mass envelopes that are highly enriched by water vapour from sublimated icy pebbles. This offers an explanation for the compositional difference between gas giants and ice giants in the solar system. Furthermore, unlike planetesimal-driven accretion scenarios, our model allows core formation and envelope attraction within disc life-times, provided that solids in protoplanetary discs are predominantly made up of pebbles. Our results imply that the outer regions of planetary systems, where the mass required to halt pebble accretion is large, are dominated by ice giants and that gas-giant exoplanets in wide orbits are enriched by more than 50 Earth masses of solids.

  3. Controlled Electronic Transport through Branched Molecular Conductors

    OpenAIRE

    2008-01-01

    Abstract The conductance through a branched conductor placed between two electrodes is analyzed using the Landauer transport formulation within the framework of the single electron, and the tight binding approximations. Terminal side chains are expressed as self energy terms which map the branched conductor onto an effective linear chain Hamiltonian. The effect of uniform side branches on resonant zero-bias conductance is shown to be analytically solvable and particularly simple, w...

  4. A new method for the asteroseismic determination of the evolutionary state of red-giant stars

    Science.gov (United States)

    Elsworth, Yvonne; Hekker, Saskia; Basu, Sarbani; Davies, Guy R.

    2017-04-01

    Determining the ages of red-giant stars is a key problem in stellar astrophysics. One of the difficulties in this determination is to know the evolutionary state of the individual stars - i.e. have they started to burn Helium in their cores? That is the topic of this paper. Asteroseismic data provide a route to achieving this information. What we present here is a highly autonomous way of determining the evolutionary state from an analysis of the power spectrum of the light curve. The method is fast and efficient and can provide results for a large number of stars. It uses the structure of the dipole-mode oscillations, which have a mixed character in red-giant stars, to determine some measures that are used in the categorization. It does not require that all the individual components of any given mode be separately characterized. Some 6604 red-giant stars have been classified. Of these, 3566 are determined to be on the red-giant branch, 2077 are red-clump and 439 are secondary-clump stars. We do not specifically identify the low-metallicity, horizontal-branch stars. The difference between red-clump and secondary-clump stars is dependent on the manner in which Helium burning is first initiated. We discuss that the way the boundary between these classifications is set may lead to mis-categorization in a small number of stars. The remaining 522 stars were not classified either because they lacked sufficient power in the dipole modes (so-called depressed dipole modes) or because of conflicting values in the parameters.

  5. Branched silver nanowires as controllable plasmon routers.

    Science.gov (United States)

    Fang, Yurui; Li, Zhipeng; Huang, Yingzhou; Zhang, Shunping; Nordlander, Peter; Halas, Naomi J; Xu, Hongxing

    2010-05-12

    Using polarization dependent scattering spectroscopy, we investigate plasmon propagation on branched silver nanowires. By controlling the polarization of the incident laser light, the wire plasmons can be routed into different wire branches and result in light emission from the corresponding wire ends. This routing behavior is found to be strongly dependent on the wavelength of light. Thus for certain incident polarizations, light of different wavelength will be routed into different branches. The branched nanowire can thus serve as a controllable router and multiplexer in integrated plasmonic circuits.

  6. Current perspectives on shoot branching regulation

    Directory of Open Access Journals (Sweden)

    Cunquan YUAN,Lin XI,Yaping KOU,Yu ZHAO,Liangjun ZHAO

    2015-03-01

    Full Text Available Shoot branching is regulated by the complex interactions among hormones, development, and environmental factors. Recent studies into the regulatory mecha-nisms of shoot branching have focused on strigolactones, which is a new area of investigation in shoot branching regulation. Elucidation of the function of the D53 gene has allowed exploration of detailed mechanisms of action of strigolactones in regulating shoot branching. In addition, the recent discovery that sucrose is key for axillary bud release has challenged the established auxin theory, in which auxin is the principal agent in the control of apical dominance. These developments increase our understan-ding of branching control and indicate that regulation of shoot branching involves a complex network. Here, we first summarize advances in the systematic regulatory network of plant shoot branching based on current information. Then we describe recent developments in the synthesis and signal transduction of strigolactones. Based on these considerations, we further summarize the plant shoot branching regulatory network, including long distance systemic signals and local gene activity mediated by strigolactones following perception of external envi-ronmental signals, such as shading, in order to provide a comprehensive overview of plant shoot branching.

  7. Networks of companies and branches in Poland

    CERN Document Server

    Chmiel, A M; Sienkiewicz, J; Suchecki, K; Chmiel, Anna M.; Holyst, Janusz A.; Sienkiewicz, Julian; Suchecki, Krzysztof

    2006-01-01

    In this study we consider relations between companies in Poland taking into account common branches they belong to. It is clear that companies belonging to the same branch compete for similar customers, so the market induces correlations between them. On the other hand two branches can be related by companies acting in both of them. To remove weak, accidental links we shall use a concept of threshold filtering for weighted networks where a link weight corresponds to a number of existing connections (common companies or branches) between a pair of nodes.

  8. Photophoresis boosts giant planet formation

    CERN Document Server

    Teiser, Jens

    2013-01-01

    In the core accretion model of giant planet formation, a solid protoplanetary core begins to accrete gas directly from the nebula when its mass reaches about 5 earth masses. The protoplanet has at most a few million years to reach runaway gas accretion, as young stars lose their gas disks after 10 million years at the latest. Yet gas accretion also brings small dust grains entrained in the gas into the planetary atmosphere. Dust accretion creates an optically thick protoplanetary atmosphere that cannot efficiently radiate away the kinetic energy deposited by incoming planetesimals. A dust-rich atmosphere severely slows down atmospheric cooling, contraction, and inflow of new gas, in contradiction to the observed timescales of planet formation. Here we show that photophoresis is a strong mechanism for pushing dust out of the planetary atmosphere due to the momentum exchange between gas and dust grains. The thermal radiation from the heated inner atmosphere and core is sufficient to levitate dust grains and to ...

  9. Giant sialocele following facial trauma.

    Science.gov (United States)

    Medeiros Júnior, Rui; Rocha Neto, Alípio Miguel da; Queiroz, Isaac Vieira; Cauby, Antônio de Figueiredo; Gueiros, Luiz Alcino Monteiro; Leão, Jair Carneiro

    2012-01-01

    Injuries in the parotid and masseter region can cause serious impairment secondary to damage of important anatomical structures. Sialocele is observed as facial swelling associated with parotid duct rupture due to trauma. The aim of this paper is to report a case of a giant traumatic sialocele in the parotid gland, secondary to a knife lesion in a 40-year-old woman. Conservative measures could not promote clinical resolution and a surgical intervention for the placement of a vacuum drain was selected. Under local anesthesia, a small incision was performed adjacent to parotid duct papilla, followed by muscular divulsion and draining of significant amount of saliva. An active vacuum suction drain was placed for 15 days, aiming to form a new salivary duct. This technique was shown to be a safe, effective and low-cost option, leading to complete resolution and no recurrence after 28 months of follow up.

  10. Studies show giant panda could survive

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The giant panda (Ailuropoda melanoleuca) is not a relic species, and it can survive, according to scientists. Employing microsatellite and mitochondrial control region (CR) sequences as genetic markers, CAS researchers have obtained some key information about the giant panda and its recent evolution history. Their discovery that the lovely creature still possesses high genetic diversity and evolution potentials challenges the hypothesis suggesting the giant panda is facing an"evolutionary dead-end." The research was reported in a recent issue of Molecular Biology and Evolution by a team of scientists led by Prof.WEI Fuwen of the CAS Institute of Zoology and Prof. Michael W.Bruford of Cardiff University.

  11. SYNOVIAL GIANT CELL TUMOR OF THE KNEE.

    Science.gov (United States)

    Abdalla, Rene Jorge; Cohen, Moisés; Nóbrega, Jezimar; Forgas, Andrea

    2009-01-01

    Synovial giant cell tumor is a benign neoplasm, rarely reported in the form of malignant metastasis. Synovial giant cell tumor most frequently occurs on the hand, and, most uncommon, on the ankle and knee. In the present study, the authors describe a rare case of synovial giant cell tumor on the knee as well as the treatment approach. Arthroscopy has been shown, in this case, to be the optimal method for treating this kind of lesion, once it allowed a less aggressive approach, while providing good visualization of all compartments of knee joint and full tumor resection.

  12. Giant Cell Tumor: Role of Conservative Treatment

    Institute of Scientific and Technical Information of China (English)

    Anatolii Diedkov[1; Pavlo Kovalchuk[1; Marija Kukushkina[2; Sergey Bojchuk[1; Viktor Kostyuk[1

    2014-01-01

    Giant cell tumor is aggressive bone tumor. Surgical treatment is considered to be the only effective method of treatment ofthese tumors. The problem of inoperable patients with giant cell tumors is a challenge. A total of 8 patients had giant cell bone tumorsof pelvis and sacrum. 3 patients were treated by bisphosphonates, radiation therapy and embolization of tumor-nutrient arteries. 5patients received denosumab. The efficiency was assessed according to clinical data and CT scan control. Median follow up is 28months. All 8 patients had reduction of pain intensity. Treatment with denosumab demonstrated more than 30% tumor regression. Allof the patients are in remission.

  13. Giant choledochal calculosis: Surgical treatment

    Directory of Open Access Journals (Sweden)

    Hasan Bektas

    2014-01-01

    Full Text Available Context: Gallstone disease is one of the most common surgical pathologies. Choledocholithiasis may occur in some of these cases and require surgical intervention. Although there are relatively non-invasive procedures such as endoscopic retrograde cholangiopancreatography (ERCP, this technique is usually unsuccessful in patients with stones larger than 10 mm. In our case, we aimed to report a giant choledochal stone (15 cm × 4.5 cm, which is rare in surgical practice and our treatment with open surgery. Case Report: The patient was a 59-year-old woman. Magnetic resonance cholangiopancreatography (MRCP had showed a hydropic gallbladder with an excessively dilated CBD and a 110 mm × 41 mm stone. In the operation, an excessively dilated CBD was seen and after choledochotomy and a very large calculus that filled CBD completely. Choledochotomy incision was carried forward and a T-tube choledochostomy with choledochoduodenostomy (CD was performed. The patient was discharged without any complications on postoperative 8 th day. Conclusion: Benign gallstone disease is a multifactorial process, with risk factors such as obesity, hemolytic diseases, diabetes mellitus, and pregnancy. Risk factors for choledocholithiasis are similar to those for gallstone disease. MRCP is a non-invasive technique in detecting choledocholithiasis. The gold standard intervention for CBD stones is ERCP. Stones in CBD may reach very considerable dimensions without causing serious symptoms. The most common symptom is jaundice. During preoperative radiological examination, giant stones may be interfered with malignancies. Surgeons should obey conventional algorithms in diagnosis and open surgery must be kept in mind in earlier stages without being too insistent on endoscopic interventions.

  14. STUDIES ON THE INGESTION CHARACTERISTICS OF GIANT FRESHWATER PRAWN, CHINESE PRAWN AND GIANT TIGER PRAWN

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The ingestion of giant freshwater prawn, Chinese prawn and giant tiger prawn had continuity and the ingestion high peak occurred at night. Light and temperature had significant effects on the daily ingestion rate (DIR) of giant freshwater prawn Macrobrachium rosenbergii. Red light and blue light favorably induced favorable ingestion. In the adaptive range of temperature, the DIR increased with rising temperature and feeding frequency, but decreased with rising body weight.

  15. Undifferentiated (Anaplastic Carcinoma of the Pancreas with Osteoclast-Like Giant Cells Showing Various Degree of Pancreas Duct Involvement. A Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Vlad Maksymov

    2011-03-01

    Full Text Available Context Undifferentiated (anaplastic carcinoma of the pancreas with osteoclast-like giant cells is exceedingly rare. The prognosis of undifferentiated carcinoma is worse than that of poorly differentiated ductal adenocarcinoma of the pancreas; however, undifferentiated carcinoma with osteoclast-like giant cells might have a more favorable prognosis. Case report We report the case of undifferentiated carcinoma of the pancreas with osteoclast-like giant cells, showing an intraductal growth pattern with various degree of pancreas duct involvement in the different areas. As a result, we were able to demonstrate the entire spectrum of changes, ranging from the early, minimal intraluminal growth to the partial or complete occlusion of the branches of the main pancreatic duct, and finally invasion and formation of the large necrotic/degenerated cysts. Conclusions Our findings support the epithelial origin of undifferentiated carcinoma of the pancreas with osteoclast-like giant cells. In early stages, the affected pancreatic duct epithelium was intermingled with nonepithelial component and had an immunoprofile distinctive from the epithelial lining of the uninvolved (normal pancreatic ducts. Distinctive immunoprofile (CK 5/6, p63 and p53 positive of the epithelial component and p63 and p53 positivity of the nonepithelial component should be explained and further investigated in the similar cases. Our findings support prior assertions that undifferentiated carcinoma of the pancreas with osteoclast-like giant cells may develop from carcinoma in situ within the main pancreatic duct or its branches

  16. Stochastic transition between turbulent branch and thermodynamic branch of an inhomogeneous plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Mitsuhiro; Itoh, Sanae-I.; Yagi, Masatoshi [Kyushu Univ., Research Institute for Applied Mechanics, Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2002-05-01

    Transition phenomena between thermodynamic branch and turbulent branch in submarginal turbulent plasma are analyzed with statistical theory. Time-development of turbulent fluctuation is obtained by numerical simulations of Langevin equation which contains submarginal characteristics. Probability density functions and transition rates between two states are analyzed. Transition from turbulent branch to thermodynamic branch occurs in almost entire region between subcritical bifurcation point and linear stability boundary. (author)

  17. Asymptotics of Simple Branching Populations

    Science.gov (United States)

    Huillet, Thierry; Kłopotowski, Andrzej; Porzio, Anna

    1995-09-01

    In this paper we study a simple deterministic tree structure: an initial individual generates a finite number of offspring, each of which has given integer valued lifetime, iterating the same procedure when dying. Three asymptotic distributions of this asynchronous deterministic branching procedure are considered: the generation distribution, the ability of individuals to generate offspring and the age distribution. Thermodynamic formalism is then developped to reveal the multifractal nature of the mass splitting associated to our process. On considère l'itération d'une structure déterministe arborescente selon laquelle un ancêtre engendre un nombre fini de descendants dont la durée de vie (à valeurs entières) est donnée. Dans un premier temps on s'intéresse aux trois distributions asymptotiques suivantes : répartition des générations, aptitude à engendrer des descendants et répartition selon l'âge. Ensuite nous développons le formalisme thermodynamique pour mettre en évidence le caractère multifractal de la scission d'une masse unitaire associée à cette arborescence.

  18. ECONOMIC ISSUES OF BRANCH PRODUCTION

    Directory of Open Access Journals (Sweden)

    Shamrov K. N.

    2015-05-01

    Full Text Available The article deals with topical questions of economy industry production of rice grain. The need for improving the business efficiency of rice today is dictated by political and economic sanctions, the needs of our society in full substitution of this important product. State stimulation of rice development today is carried out through a complex of economic and administrative activities. The economic measures of the state include: price control on rice price and processing products, support of agricultural producers’ incomes, leasing involving the state, marketing of products, and infrastructure development of the grain market. The system of public administrative measures also includes standardization and certification of grain products, control quality of grain and products of its processing, the quarantine protection, licensing activities organizations, and mandatory statistical account of the rice market. These measures are intended to ensure equal conditions of competition between local and imported rice, to spur investment and expansion of domestic production, increase profitability of rice, allowing the rice enterprises to carry out expensive irrigation systems repairs and capital inputs in lot lend. The article suggests that rice branch industry remains competitive and with abolition of import customs barriers within frameworks WTO. It is necessary to invest more heavily in infrastructure with the aim of improving business efficiency of rice

  19. Giant saphenous vein graft pseudoaneurysm to right posterior descending artery presenting with superior vena cava syndrome

    Institute of Scientific and Technical Information of China (English)

    Andres; Vargas-Estrada; Dianna; Edwards; Mohammad; Bashir; James; Rossen; Firas; Zahr

    2015-01-01

    Saphenous vein grafts(SVG) pseudoaneurysms,especially giant ones,are rare and occur as a late complication of coronary artery bypass grafting. This condition affects both genders and typically occurs within the sixth decade of life. The clinical presentation ranges from an asymptomatic incidental finding on imaging studies to new onset angina,dyspnea,myocardial infarction or symptoms related to compression of neighboring structures. An 82-year-old woman presented with acute onset back pain,dyspnea and was noted to have significantly engorged neck veins. In the emergency department,a chest computed tomographic angiogram with intravenous contrast revealed a ruptured giant bilobed SVG pseudoaneurysm to the right posterior descending artery(RPDA). This imaging modality also demonstrated compression of the superior vena cava(SVC) by the SVG pseudoaneurysm. Coronary angiogram with bypass study was performed to establish the patency of this graft. Endovascular coiling and embolization of the SVG to RPDA was initially considered but disfavored after the coronary angiogram revealed preserved flow from the graft to this arterial branch. After reviewing the angiogram films,a surgical strategy was favored over a percutaneous intervention with a Nitinol self-expanding stent since the latter would have not addressed the superior vena cava compression caused by the giant pseudoaneurysm. Intraoperative transesophageal echocardiogram demonstrated SVCcompression by the giant pseudoaneurysm cranial lobe. Our patient underwent surgical ligation and excision of the giant pseudoaneurysm and the RPDA was regrafted successfully. In summary,saphenous vein grafts pseudoaneurysms can be life-threatening and its therapy should be guided based on the presence of mechanical complications,the patency of the affected vein graft and the involved myocardial territory viability.

  20. An archetypal mechanism for branching organogenesis.

    Science.gov (United States)

    Clément, Raphaël; Mauroy, Benjamin

    2014-02-01

    Branched structures are ubiquitous in nature, both in living and non-living systems. While the functional benefits of branching organogenesis are straightforward, the developmental mechanisms leading to the repeated branching of epithelia in surrounding mesoderm remain unclear. Both molecular and physical aspects of growth control seem to play a critical role in shape emergence and maintenance. On the molecular side, the existence of a gradient of growth-promoting ligand between epithelial tips and distal mesenchyme seems to be common to branched organs. On the physical side, the branching process seems to require a mechanism of real-time adaptation to local geometry, as suggested by the self-avoiding nature of branching events. In this paper, we investigate the outcomes of a general three-dimensional growth model, in which epithelial growth is implemented as a function of ligand income, while the mesenchyme is considered as a proliferating viscous medium. Our results suggest that the existence of a gradient of growth-promoting ligand between distal and proximal mesenchyme implies a growth instability of the epithelial sheet, resulting in spontaneous self-avoiding branching morphogenesis. While the general nature of the model prevents one from fitting the development of specific organs, it suggests that few ingredients are actually required to achieve branching organogenesis.

  1. AFSC/ABL: Female Giant Grenadier maturity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Giant grenadiers Albatrossia pectoralis are caught as bycatch in deep-sea commercial fisheries in relatively large numbers. The population appears to be stable,...

  2. growing African giant rats Cricetomys gambianus

    African Journals Online (AJOL)

    bolism, conductance and evaporative water loss changes in relation to physical and behavioural development in growing giant rat pups ... evaporation) into dry air was collected in a pre-weighed column of silica ..... Principles and adaptation.

  3. Giant prostatic fossa with misleading radiographic features.

    Science.gov (United States)

    Stenzl, A; Fuchs, G J

    1989-01-01

    The long-term complication of a perforation of the prostatic capsule during transurethral resection of the prostate is described. Calcifications in a giant prostatic fossa led to initially misleading radiologic findings.

  4. Giant planet and brown dwarf formation

    CERN Document Server

    Chabrier, G; Janson, M; Rafikov, R

    2014-01-01

    Understanding the dominant brown dwarf and giant planet formation processes, and finding out whether these processes rely on completely different mechanisms or share common channels represents one of the major challenges of astronomy and remains the subject of heated debates. It is the aim of this review to summarize the latest developments in this field and to address the issue of origin by confronting different brown dwarf and giant planet formation scenarios to presently available observational constraints. As examined in the review, if objects are classified as "Brown Dwarfs" or "Giant Planets" on the basis of their formation mechanism, it has now become clear that their mass domains overlap and that there is no mass limit between these two distinct populations. Furthermore, while there is increasing observational evidence for the existence of non-deuterium burning brown dwarfs, some giant planets, characterized by a significantly metal enriched composition, might be massive enough to ignite deuterium bur...

  5. Giant Cell Arteritis: An Atypical Presentation Diagnosed with the Use of MRI Imaging

    Directory of Open Access Journals (Sweden)

    Siddesh Shambhu

    2016-01-01

    Full Text Available Giant cell arteritis (GCA is the most common primary systemic vasculitis in western countries in individuals over the age of 50. It is typically characterised by the granulomatous involvement of large and medium sized blood vessels branching of the aorta with particular tendencies for involving the extracranial branches of the carotid artery. Generally the diagnosis is straightforward when characteristic symptoms such as headache, jaw claudication, or other ischemic complications are present. Atypical presentations of GCA without “overt” cranial ischemic manifestations have become increasingly recognised but we report for the first time a case of GCA presenting as mild upper abdominal pain and generalized weakness in the context of hyponatremia as the presenting manifestation of vasculitis that was subsequently diagnosed by MRI scanning. This case adds to the literature and emphasises the importance of MRI in the evaluation of GCA patients without “classic” cranial ischemic symptoms.

  6. Deformation effects in Giant Monopole Resonance

    CERN Document Server

    Kvasil, J; Repko, A; Bozik, D; Kleinig, W; Reinhard, P -G

    2014-01-01

    The isoscalar giant monopole resonance (GMR) in Samarium isotopes (from spherical $^{144}$Sm to deformed $^{148-154}$Sm) is investigated within the Skyrme random-phase-approximation (RPA) for a variety of Skyrme forces. The exact RPA and its separable version (SRPA) are used for spherical and deformed nuclei, respectively. The quadrupole deformation is shown to yield two effects: the GMR broadens and attains a two-peak structure due to the coupling with the quadrupole giant resonance.

  7. Giant rhinophyma: Excision with coblation assisted surgery

    Directory of Open Access Journals (Sweden)

    Caner Sahin

    2014-01-01

    Full Text Available An 83-year-old man presented with an unusually severe case of rhinophyma. Giant rhinopyhma is very rare in literature. The giant lesion was widely excised using sharp surgical incision and coblation assisted surgery. Using direct coblation to the nasal dorsum may cause edema in the surrounding tissue. There was minimal edema in surrounding tissue using this technique. A full thickness-skin graft was applied after excision. Cosmetic and functional postoperative results were satisfactory.

  8. Giant rhinophyma: Excision with coblation assisted surgery.

    Science.gov (United States)

    Sahin, Caner; Turker, Mesut; Celasun, Bulent

    2014-01-01

    An 83-year-old man presented with an unusually severe case of rhinophyma. Giant rhinopyhma is very rare in literature. The giant lesion was widely excised using sharp surgical incision and coblation assisted surgery. Using direct coblation to the nasal dorsum may cause edema in the surrounding tissue. There was minimal edema in surrounding tissue using this technique. A full thickness-skin graft was applied after excision. Cosmetic and functional postoperative results were satisfactory.

  9. Taxonomy of Indonesian giant clams (Cardiidae, Tridacninae)

    OpenAIRE

    UDHI EKO HERNAWAN

    2012-01-01

    Hernawan E. 2012. Taxonomy of Indonesian giant clams (Cardiidae, Tridacninae). Biodiversitas 13: 118-123. A taxonomic study was conducted on the giant clam’s specimens deposited in Museum Zoologicum Bogoriense (MZB), Cibinong Indonesia. Taxonomic overviews of the examined specimens are given with diagnostic characters, remarks, habitat and distribution. Discussion is focused on specific characters distinguishing each species. From seven species known to distribute in Indonesian waters, there ...

  10. Perianal Giant Condyloma Acuminatum: A Case Report

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Rare giant condyloma acuminatum (CA) reported by this paper is an interesting unusual case in China. Giant CA is a tumor that primarily affects the genital and perianal areas. Its feature is the high rate of local recurrence and transformation into squamous cell carcinoma. Making choice of wide surgical excision and using interferon as antiviral and immunoenhancement for CA after operation, we obtain satisfactory functional and cosmetic results.

  11. Testing planet formation theories with Giant stars

    CERN Document Server

    Pasquini, Luca; Hatzes, A; Setiawan, J; Girardi, L; da Silva, L; De Medeiros, J R

    2008-01-01

    Planet searches around evolved giant stars are bringing new insights to planet formation theories by virtue of the broader stellar mass range of the host stars compared to the solar-type stars that have been the subject of most current planet searches programs. These searches among giant stars are producing extremely interesting results. Contrary to main sequence stars planet-hosting giants do not show a tendency of being more metal rich. Even if limited, the statistics also suggest a higher frequency of giant planets (at least 10 %) that are more massive compared to solar-type main sequence stars. The interpretation of these results is not straightforward. We propose that the lack of a metallicity-planet connection among giant stars is due to pollution of the star while on the main sequence, followed by dilution during the giant phase. We also suggest that the higher mass and frequency of the planets are due to the higher stellar mass. Even if these results do not favor a specific formation scenario, they su...

  12. Bayesian Inference of Giant Exoplanet Physics

    Science.gov (United States)

    Thorngren, Daniel; Fortney, Jonathan J.

    2017-01-01

    The physical processes within a giant planet directly set its observed radius for a given mass, age, and insolation. The important aspects are the planet’s bulk composition and its interior thermal evolution. By studying many giant planets as an ensemble, we can gain insight into this physics. We demonstrate two novel examples here. We examine 50 cooler transiting giant planets, whose insolation is sufficiently low (T_eff < 1000 K) that they are not affected by the hot Jupiter radius inflation effect. For these planets, the thermal evolution is relatively well understood, and we show that the bulk planet metallicity increases with the total planet mass, which directly impacts plans for future atmospheric studies. We also examine the relation with stellar metallicity and discuss how these relations place new constraints on the core accretion model of planet formation. Our newest work seeks to quantify the flow of energy into hot Jupiters needed to explain their enlarged radii, in addition to their bulk composition. Because the former is related to stellar insolation and the latter is related to mass, we are able to create a hierarchical Bayesian model to disentangle the two effects in our sample of ~300 transiting giant planets. Our results show conclusively that the inflation power is not a simple fraction of stellar insolation: instead, the power increases with incident flux at a much higher rate. We use these results to test published models of giant planet inflation and to provide accurate empirical mass-radius relations for giant planets.

  13. Mechanisms of side branching and tip splitting in a model of branching morphogenesis.

    Directory of Open Access Journals (Sweden)

    Yina Guo

    Full Text Available Recent experimental work in lung morphogenesis has described an elegant pattern of branching phenomena. Two primary forms of branching have been identified: side branching and tip splitting. In our previous study of lung branching morphogenesis, we used a 4 variable partial differential equation (PDE, due to Meinhardt, as our mathematical model to describe the reaction and diffusion of morphogens creating those branched patterns. By altering key parameters in the model, we were able to reproduce all the branching styles and the switch between branching modes. Here, we attempt to explain the branching phenomena described above, as growing out of two fundamental instabilities, one in the longitudinal (growth direction and the other in the transverse direction. We begin by decoupling the original branching process into two semi-independent sub-processes, 1 a classic activator/inhibitor system along the growing stalk, and 2 the spatial growth of the stalk. We then reduced the full branching model into an activator/inhibitor model that embeds growth of the stalk as a controllable parameter, to explore the mechanisms that determine different branching patterns. We found that, in this model, 1 side branching results from a pattern-formation instability of the activator/inhibitor subsystem in the longitudinal direction. This instability is far from equilibrium, requiring a large inhomogeneity in the initial conditions. It successively creates periodic activator peaks along the growing stalk, each of which later on migrates out and forms a side branch; 2 tip splitting is due to a Turing-style instability along the transversal direction, that creates the spatial splitting of the activator peak into 2 simultaneously-formed peaks at the growing tip, the occurrence of which requires the widening of the growing stalk. Tip splitting is abolished when transversal stalk widening is prevented; 3 when both instabilities are satisfied, tip bifurcation occurs

  14. Separating gas-giant and ice-giant planets by halting pebble accretion

    CERN Document Server

    Lambrechts, Michiel; Morbidelli, Alessandro

    2014-01-01

    In the Solar System giant planets come in two flavours: 'gas giants' (Jupiter and Saturn) with massive gas envelopes and 'ice giants' (Uranus and Neptune) with much thinner envelopes around their cores. It is poorly understood how these two classes of planets formed. High solid accretion rates, necessary to form the cores of giant planets within the life-time of protoplanetary discs, heat the envelope and prevent rapid gas contraction onto the core, unless accretion is halted. We find that, in fact, accretion of pebbles (~ cm-sized particles) is self-limiting: when a core becomes massive enough it carves a gap in the pebble disc. This halt in pebble accretion subsequently triggers the rapid collapse of the super-critical gas envelope. As opposed to gas giants, ice giants do not reach this threshold mass and can only bind low-mass envelopes that are highly enriched by water vapour from sublimated icy pebbles. This offers an explanation for the compositional difference between gas giants and ice giants in the S...

  15. Giant hepatocellular adenoma; case report

    Energy Technology Data Exchange (ETDEWEB)

    Pitella, F.A.; Coutinho, A.M.N.; Coura Filho, G.B.; Costa, P.L.A.; Ono, C.R.; Watanabe, T.; Sapienza, M.T.; Hironaka, F.; Cerri, G.G.; Buchpiguel, C.A. [Universidade de Sao Paulo (FM/USP), SP (Brazil). Inst. de Radiologia. Servico de Medicina Nuclear

    2008-07-01

    Full text: Introduction: Hepatocellular adenoma is a benign hepatic tumor identified mainly in women during fertility age, with estimated incidence of 4/1000 inhabitants. It is usually unique, well circumscribed, with or without a capsule, size varying from 1 to 30 cm, with possible central areas of necrosis and hemorrhage. Case Report: A 37-year-old female patient presenting with no comorbities, use of hormonal birth control pills for 18 years, a condition of reduction in the consistency of feces, increase in number of daily defecations, abdominal cramps, and a stuffed sensation after meals for two years. A palpable abdominal mass extending from the right hypochondriac to the right iliac fossa was noticed four months ago. A computerized tomography (CT) showed an extensive hepatic mass on the right which was considered, within the diagnostic hypotheses, hepatic adenomatosis, without ruling out secondary lesions. A hepatic scintillography with {sup 99m}Tc-DISIDA showed an extensive exophytic area from segment V to the right iliac fossa with arterialized blood flow and hepatocytic activity, as well as a hepatic nodule in segment VII with hepatocytic activity consistent with the hepatic adenomas hypothesis. The biopsy confirmed the hepatic adenoma diagnosis and the patient was submitted to a partial hepatectomy and cholecystectomy with good clinical evolution. Conclusion: Nuclear Medicine may supplement the assessment of hepatic nodules, including giant masses, thus suggesting new hypotheses and direction to therapeutic conduct. (author)

  16. Migration of accreting giant planets

    Science.gov (United States)

    Crida, A.; Bitsch, B.; Raibaldi, A.

    2016-12-01

    We present the results of 2D hydro simulations of giant planets in proto-planetary discs, which accrete gas at a more or less high rate. First, starting from a solid core of 20 Earth masses, we show that as soon as the runaway accretion of gas turns on, the planet is saved from type I migration : the gap opening mass is reached before the planet is lost into its host star. Furthermore, gas accretion helps opening the gap in low mass discs. Consequently, if the accretion rate is limited to the disc supply, then the planet is already inside a gap and in type II migration. We further show that the type II migration of a Jupiter mass planet actually depends on its accretion rate. Only when the accretion is high do we retrieve the classical picture where no gas crosses the gap and the planet follows the disc spreading. These results impact our understanding of planet migration and planet population synthesis models. The e-poster presenting these results in French can be found here: L'e-poster présentant ces résultats en français est disponible à cette adresse: http://sf2a.eu/semaine-sf2a/2016/posterpdfs/156_179_49.pdf.

  17. Endoscopically removed giant submucosal lipoma

    Directory of Open Access Journals (Sweden)

    Jovanović Ivan

    2007-01-01

    Full Text Available Background. Although uncommon, giant submucosal colon lipomas merit attention as they are often presented with dramatic clinical features such as bleeding, acute bowel obstruction, perforation and sometimes may be mistaken for malignancy. There is a great debate in the literature as to how to treat them. Case report. A patient, 67-year old, was admitted to the Clinic due to a constipation over the last several months, increasing abdominal pain mainly localized in the left lower quadrant accompanied by nausea, vomiting and abdominal distension. Physical examination was unremarkable and the results of the detailed laboratory tests and carcinoembryonic antigen remained within normal limits. Colonoscopy revealed a large 10 cm long, and 4 to 5 cm in diameter, mobile lesion in his sigmoid colon. Conventional endoscopic ultrasound revealed 5 cm hyperechoic lesion of the colonic wall. Twenty MHz mini-probe examination showed that lesion was limited to the submucosa. Since polyp appeared too large for a single transaction, it was removed piecemeal. Once the largest portion of the polyp has been resected, it was relatively easy to place the opened snare loop around portions of the residual polyp. Endoscopic resection was carried out safely without complications. Histological examination revealed the common typical histological features of lipoma elsewhere. The patient remained stable and eventually discharged home. Four weeks later he suffered no recurrent symptoms. Conclusion. Colonic lipomas can be endoscopically removed safely eliminating unnecessary surgery.

  18. Measurement of Prominent eta Decay Branching Fractions

    CERN Document Server

    López, A; Méndez, H; Ramírez, J; Ge, J Y; Miller, D H; Sanghi, B; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Menaa, N; Mountain, R; Nisar, S; Randrianarivony, K; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Asner, D M; Edwards, K W; Naik, P; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Adam, N E; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A G; Ernst, J; Ecklund, K M; Severini, H; Love, W; Savinov, V

    2007-01-01

    The decay psi(2S) --> eta J/psi is used to measure, for the first time, all prominent eta-meson branching fractions with the same experiment in the same dataset, thereby providing a consistent treatment of systematics across branching fractions. We present results for eta decays to gamma gamma, pi+pi-pi0, 3 pi0, pi+ pi- gamma, and e+ e- gamma, accounting for 99.9% of all eta decays. The precisions for several of the branching fractions and their ratios are improved. Two channels, pi+ pi- gamma and e+ e- gamma, show results that differ at the level of three standard deviations from those previously determined.

  19. Agents in branching space-times

    Institute of Scientific and Technical Information of China (English)

    Nuel; Belnap

    2003-01-01

    The aim of this essay Is to make some brief suggestions on the beginnings of a theory of agentsand agency In branching spacetlmes.foe thought Is to combine the ideas of agency as developed agalnst the relatively simple background of branching time with the richer notions of Indetermlnlsm asstructured In the theory of branching space-times.My plan Is to say a little about agency In branchingtime and a little about branchlg spacetlmes,and then ask how the two can be brought together.Atthe end there Is an ...

  20. Cellular and physical mechanisms of branching morphogenesis

    Science.gov (United States)

    Varner, Victor D.; Nelson, Celeste M.

    2014-01-01

    Branching morphogenesis is the developmental program that builds the ramified epithelial trees of various organs, including the airways of the lung, the collecting ducts of the kidney, and the ducts of the mammary and salivary glands. Even though the final geometries of epithelial trees are distinct, the molecular signaling pathways that control branching morphogenesis appear to be conserved across organs and species. However, despite this molecular homology, recent advances in cell lineage analysis and real-time imaging have uncovered surprising differences in the mechanisms that build these diverse tissues. Here, we review these studies and discuss the cellular and physical mechanisms that can contribute to branching morphogenesis. PMID:25005470

  1. Tillering and panicle branching genes in rice.

    Science.gov (United States)

    Liang, Wei-hong; Shang, Fei; Lin, Qun-ting; Lou, Chen; Zhang, Jing

    2014-03-01

    Rice (Oryza sativa L.) is one of the most important staple food crops in the world, and rice tillering and panicle branching are important traits determining grain yield. Since the gene MONOCULM 1 (MOC 1) was first characterized as a key regulator in controlling rice tillering and branching, great progress has been achieved in identifying important genes associated with grain yield, elucidating the genetic basis of yield-related traits. Some of these important genes were shown to be applicable for molecular breeding of high-yielding rice. This review focuses on recent advances, with emphasis on rice tillering and panicle branching genes, and their regulatory networks.

  2. The return branch of viscous fingers

    CERN Document Server

    Vera, F

    2005-01-01

    We report a simple experiment of two-dimensional pattern formation in a circular Hele-Shaw cell, showing the appearance of a return branch that is equivalent to the upward-connecting leader of lightning. Injecting water from the center into a foam filled cell, we obtained patterns similar to dendrites of two-dimensional dielectric breakdown experiments. When we repeat this experiment allowing the presence of water in the outer (low pressure) region, dendrites grow initially as in a normal experiment, but when a branch is near the outer boundary, the low pressure water begins to penetrate the foam against the pressure field, forming several return branches.

  3. Giant elves: Lightning-generated electromagnetic pulses in giant planets.

    Science.gov (United States)

    Luque Estepa, Alejandro; Dubrovin, Daria; José Gordillo-Vázquez, Francisco; Ebert, Ute; Parra-Rojas, Francisco Carlos; Yair, Yoav; Price, Colin

    2015-04-01

    We currently have direct optical observations of atmospheric electricity in the two giant gaseous planets of our Solar System [1-5] as well as radio signatures that are possibly generated by lightning from the two icy planets Uranus and Neptune [6,7]. On Earth, the electrical activity of the troposphere is associated with secondary electrical phenomena called Transient Luminous Events (TLEs) that occur in the mesosphere and lower ionosphere. This led some researchers to ask if similar processes may also exist in other planets, focusing first on the quasi-static coupling mechanism [8], which on Earth is responsible for halos and sprites and then including also the induction field, which is negligible in our planet but dominant in Saturn [9]. However, one can show that, according to the best available estimation for lightning parameters, in giant planets such as Saturn and Jupiter the effect of the electromagnetic pulse (EMP) dominates the effect that a lightning discharge has on the lower ionosphere above it. Using a Finite-Differences, Time-Domain (FDTD) solver for the EMP we found [10] that electrically active storms may create a localized but long-lasting layer of enhanced ionization of up to 103 cm-3 free electrons below the ionosphere, thus extending the ionosphere downward. We also estimate that the electromagnetic pulse transports 107 J to 1010 J toward the ionosphere. There emissions of light of up to 108 J would create a transient luminous event analogous to a terrestrial elve. Although these emissions are about 10 times fainter than the emissions coming from the lightning itself, it may be possible to target them for detection by filtering the appropiate wavelengths. [1] Cook, A. F., II, T. C. Duxbury, and G. E. Hunt (1979), First results on Jovian lightning, Nature, 280, 794, doi:10.1038/280794a0. [2] Little, B., C. D. Anger, A. P. Ingersoll, A. R. Vasavada, D. A. Senske, H. H. Breneman, W. J. Borucki, and The Galileo SSI Team (1999), Galileo images of

  4. Overview of the Advanced High Frequency Branch

    Science.gov (United States)

    Miranda, Felix A.

    2015-01-01

    This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch.

  5. Human Dimensions Branch 2016 Annual Report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual report provides an overview of the work that the Human Dimensions Branch completed in FY2016, including a peak at: Monarch butterfly conservation and how...

  6. Residence times of branching diffusion processes

    Science.gov (United States)

    Dumonteil, E.; Mazzolo, A.

    2016-07-01

    The residence time of a branching Brownian process is the amount of time that the mother particle and all its descendants spend inside a domain. Using the Feynman-Kac formalism, we derive the residence-time equation as well as the equations for its moments for a branching diffusion process with an arbitrary number of descendants. This general approach is illustrated with simple examples in free space and in confined geometries where explicit formulas for the moments are obtained within the long time limit. In particular, we study in detail the influence of the branching mechanism on those moments. The present approach can also be applied to investigate other additive functionals of branching Brownian process.

  7. FY 1990 Applied Sciences Branch annual report

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.M.; Dippo, P.C. (eds.)

    1991-11-01

    The Applied Sciences Branch actively supports the advancement of DOE/SERI goals for the development and implementation of the solar photovoltaic technology. The primary focus of the laboratories is to provide state-of-the-art analytical capabilities for materials and device characterization and fabrication. The branch houses a comprehensive facility which is capable of providing information on the full range of photovoltaic components. A major objective of the branch is to aggressively pursue collaborative research with other government laboratories, universities, and industrial firms for the advancement of photovoltaic technologies. Members of the branch disseminate research findings to the technical community in publications and presentations. This report contains information on surface and interface analysis, materials characterization, development, electro-optical characterization module testing and performance, surface interactions and FTIR spectroscopy.

  8. Damping by branching: a bioinspiration from trees

    CERN Document Server

    Theckes, Benoit; Boutillon, Xavier

    2011-01-01

    Man-made slender structures are known to be sensitive to high levels of vibration, due to their flexibility, which often cause irreversible damage. In nature, trees repeatedly endure large amplitudes of motion, mostly caused by strong climatic events, yet with minor or no damage in most cases. A new damping mechanism inspired by the architecture of trees is here identified and characterized in the simplest tree-like structure, a Y-shape branched structure. Through analytical and numerical analyses of a simple two-degree-of-freedom model, branching is shown to be the key ingredient in this protective mechanism that we call damping-by-branching. It originates in the geometrical nonlinearities so that it is specifically efficient to damp out large amplitudes of motion. A more realistic model, using flexible beam approximation, shows that the mechanism is robust. Finally, two bioinspired architectures are analyzed, showing significant levels of damping achieved via branching with typically 30% of the energy being...

  9. Arkansas State University Beebe Branch Faculty Handbook.

    Science.gov (United States)

    Arkansas State Univ., Beebe.

    Arkansas State University Beebe Branch provides a liberal arts oriented program for traditional and nontraditional students. Its faculty handbook contains institutional goals, description of responsibilities of administrative officers and faculty committees, faculty employment policies, and administrative and instructional policies. The…

  10. Surgical repair of pulmonary artery branches.

    Science.gov (United States)

    Ghez, Olivier; Saeed, Imran; Serrato, Maria; Quintero, Diana Bernal; Kreitmann, Bernard; Fraisse, Alain; Uemura, Hideki; Seale, Anna; Daubeney, Piers; McCarthy, Karen; Ho, S Yen

    2013-01-01

    Surgical repair of pulmonary artery (PA) branches encompasses many different clinical scenarios and technical challenges. The most common, such as bifurcation and central PA reconstruction, are described, as well as the challenges of complex and peripheral reconstruction.

  11. Chemical Abundances in a Sample of Red Giants in the Open Cluster NGC 2420 from APOGEE

    CERN Document Server

    Souto, Diogo; Smith, Verne; Prieto, Carlos Allende; Pinsonneault, Marc; Zamora, Olga; García-Hernández, D Anibal; Bovy, Szabolcs Meszaros Jo; Pérez, Ana Elia García; Anders, Friedrich; Bizyaev, Dmitry; Carrera, Ricardo; Frinchaboy, Peter; Holtzman, Jon; Ivans, Inese; Majewski, Steve; Shetrone, Matthew; Sobeck, Jennifer; Pan, Kaike; Tang, Baitian; Villanova, Sandro; Geisler, Douglas

    2016-01-01

    NGC 2420 is a $\\sim$2 Gyr-old well-populated open cluster that lies about 2 kpc beyond the solar circle, in the general direction of the Galactic anti-center. Most previous abundance studies have found this cluster to be mildly metal-poor, but with a large scatter in the obtained metallicities for this open cluster. Detailed chemical abundance distributions are derived for 12 red-giant members of NGC 2420 via a manual abundance analysis of high-resolution (R = 22,500) near-infrared ($\\lambda$1.5 - 1.7$\\mu$m) spectra obtained from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. The sample analyzed contains 6 stars that are identified as members of the first-ascent red giant branch (RGB), as well as 6 members of the red clump (RC). We find small scatter in the star-to-star abundances in NGC 2420, with a mean cluster abundance of [Fe/H] = -0.16 $\\pm$ 0.04 for the 12 red giants. The internal abundance dispersion for all elements (C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Co and Ni...

  12. EPIC 211351816.01: A (Re-?)Inflated Planet Orbiting a Red Giant Star

    CERN Document Server

    Grunblatt, Samuel K; Gaidos, Eric J; Lopez, Eric D; Fulton, Benjamin J; Fortney, Jonathan J; Howard, Andrew W; Sinukoff, Evan J; Mann, Andrew W; Isaacson, Howard

    2016-01-01

    Giant planets with high incident fluxes have been observed with radii larger than thermal evolution models would allow. Although these inflated planets have been known for almost two decades, it is unclear whether their inflation is caused by deposition of energy from the host star, or inhibited cooling of the planet. These processes can be distinguished if the planet becomes highly irradiated only when the host star evolves onto the red giant branch. We report the discovery of EPIC 211351816.01, a 1.27 +/- 0.09 RJ, 1.10 +/- 0.11 MJ planet orbiting a 4.20 +/- 0.14 Rsun, 1.16 +/- 0.12 Msun red giant star with an orbital period of 8.4 days. We precisely constrained stellar and planetary parameters by combining asteroseismology, spectroscopy, and granulation noise modeling along with transit and radial velocity measurements. Our calculations suggest the incident flux on this planet was ~200 +/- 100 times the flux on Earth while the star was on the main sequence, comparable to the suggested threshold flux for pla...

  13. Suppression of quadrupole and octupole modes in red giants observed by Kepler

    CERN Document Server

    Stello, D; Fuller, J; Garcia, R A; Huber, D

    2016-01-01

    The asteroseismology of red giant stars has continued to yield surprises since the onset of high-precision photometry from space-based observations. An exciting new theoretical result shows that the previously observed suppression of dipole oscillation modes in red giants can be used to detect strong magnetic fields in the stellar cores. A fundamental facet of the theory is that nearly all the mode energy leaking into the core is trapped by the magnetic greenhouse effect. This results in clear predictions for how the mode visibility changes as a star evolves up the red giant branch, and how that depends on stellar mass, spherical degree, and mode lifetime. Here, we investigate the validity of these predictions with a focus on the visibility of different spherical degrees. We find that mode suppression weakens for higher degree modes with an average reduction in the quadrupole mode visibility of up to 49% for the least evolved stars in our sample, and no detectable suppression of octupole modes, in agreement w...

  14. Solar-like Oscillations in Low-luminosity Red Giants: First Results from Kepler

    DEFF Research Database (Denmark)

    Bedding, T. R.; Huber, D.; Stello, D.;

    2010-01-01

    We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30 minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from...... the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Δν) and the frequency of maximum power (νmax). We focus on a sample of 50 low-luminosity stars (νmax > 100 μHz, L 30 L ) having high signal-to-noise ratios and showing...... the unambiguous signature of solar-like oscillations. These are H-shell-burning stars, whose oscillations should be valuable for testing models of stellar evolution and for constraining the star formation rate in the local disk. We use a new technique to compare stars on a single échelle diagram by scaling...

  15. Asteroseismology of Red Giants from the First Four Months of Kepler Data

    DEFF Research Database (Denmark)

    Huber, Daniel; Bedding, Timothy R.; Stello, Dennis;

    2010-01-01

    We have studied solar-like oscillations in ~800 red giant stars using Kepler long-cadence photometry. The sample includes stars ranging in evolution from the lower part of the red giant branch to the helium main sequence. We investigate the relation between the large frequency separation (Δν......) and the frequency of maximum power (νmax) and show that it is different for red giants than for main-sequence stars, which is consistent with evolutionary models and scaling relations. The distributions of νmax and Δν are in qualitative agreement with a simple stellar population model of the Kepler field, including...... the first evidence for a secondary clump population characterized by M >~ 2 M sun and νmax ~= 40-110 μHz. We measured the small frequency separations δν02 and δν01 in over 400 stars and δν03 in over 40. We present C-D diagrams for l = 1, 2, and 3 and show that the frequency separation ratios δν02/Δν and δν...

  16. Five groups of red giants with distinct chemical composition in the globular cluster NGC 2808

    CERN Document Server

    Carretta, Eugenio

    2015-01-01

    The chemical composition of multiple populations in the massive globular cluster (GC) NGC~2808 is addressed with the homogeneous abundance re-analysis of 140 red giant branch (RGB) stars. UVES spectra for 31 stars and GIRAFFE spectra for the other giants were analysed with the same procedures used for about 2500 giants in 23 GCs in our FLAMES survey, deriving abundances of Fe, O, Na, Mg, Si, Ca, Ti, Sc, Cr, Mn, and Ni. Iron, elements from alpha-capture, and in the Fe-group do not show intrinsic scatter. On our UVES scale the metallicity of NGC~2808 is [Fe/H]=-1.129+/-0.005+/-0.034$ (+/-statistical +/-systematic error) with sigma=0.030 (31 stars). Main features related to proton-capture elements are retrieved, but the improved statistics and the smaller associated internal errors allow to uncover five distinct groups of stars along the Na-O anticorrelation. We observe large depletions in Mg, anticorrelated with enhancements of Na and also Si, suggestive of unusually high temperatures for proton-captures. About...

  17. Solar-like oscillations in low-luminosity red giants: first results from Kepler

    CERN Document Server

    Bedding, T R; Stello, D; Elsworth, Y P; Hekker, S; Kallinger, T; Mathur, S; Mosser, B; Preston, H L; Ballot, J; Barban, C; Broomhall, A M; Buzasi, D L; Chaplin, W J; Garcia, R A; Gruberbauer, M; Hale, S J; De Ridder, J; Frandsen, S; Borucki, W J; Brown, T; Christensen-Dalsgaard, J; Gilliland, R L; Jenkins, J M; Kjeldsen, H; Koch, D; Belkacem, K; Bildsten, L; Bruntt, H; Campante, T L; Deheuvels, S; Derekas, A; Dupret, M -A; Goupil, M -J; Hatzes, A; Houdek, G; Ireland, M J; Jiang, C; Karoff, C; Kiss, L L; Lebreton, Y; Miglio, A; Montalban, J; Noels, A; Roxburgh, I W; Sangaralingam, V; Stevens, I R; Suran, M D; Tarrant, N J; Weiss, A

    2010-01-01

    We have measured solar-like oscillations in red giants using time-series photometry from the first 34 days of science operations of the Kepler Mission. The light curves, obtained with 30-minute sampling, reveal clear oscillations in a large sample of G and K giants, extending in luminosity from the red clump down to the bottom of the giant branch. We confirm a strong correlation between the large separation of the oscillations (Delta nu) and the frequency of maximum power (nu_max). We focus on a sample of 50 low-luminosity stars (nu_max > 100 muHz, L <~ 30 L_sun) having high signal-to-noise ratios and showing the unambiguous signature of solar-like oscillations. These are H-shell-burning stars, whose oscillations should be valuable for testing models of stellar evolution and for constraining the star-formation rate in the local disk. We use a new technique to compare stars on a single echelle diagram by scaling their frequencies and find well-defined ridges corresponding to radial and non-radial oscillatio...

  18. High surface magnetic field in red giants as a new signature of planet engulfment?

    CERN Document Server

    Privitera, Giovanni; Eggenberger, Patrick; Georgy, Cyril; Ekström, Sylvia; Vidotto, Aline A; Bianda, Michele; Villaver, Eva; ud-Doula, Asif

    2016-01-01

    Context. Red-giant stars may engulf planets. This may increase the rotation rate of their convective envelope, which could lead to strong dynamo-triggered magnetic fields. Aims. We explore the possibility of generating magnetic fields in red giants that have gone through the process of a planet engulfment. We compare them with similar models that evolve without any planets. We discuss the impact of stellar wind magnetic braking on the evolution of the surface velocity of the parent star. Methods. With rotating stellar models with and without planets and an empirical relation between the Rossby number and the surface magnetic field, we deduce the evolution of the surface magnetic field along the red-giant branch. The effects of wind magnetic braking is explored using a relation deduced from MHD simulations. Results. The stellar evolution model of a 1.7 M$_\\odot$ without planet engulfment and that has a time-averaged rotation velocity during the Main-Sequence equal to 100 km s$^{-1}$, shows a surface magnetic f...

  19. Chemical tagging of three distinct populations of red giants in the globular cluster NGC 6752

    CERN Document Server

    Carretta, Eugenio; Gratton, Raffaele; Lucatello, Sara; D'Orazi, Valentina

    2012-01-01

    We present aluminium, magnesium, and silicon abundances in the metal-poor globular cluster NGC 6752 for a sample of more than 130 red giants with homogeneous oxygen and sodium abundances. We find that [Al/Fe] shows a spread of about 1.4 dex among giants in NGC 6752 and is anticorrelated with [Mg/Fe] and [O/Fe] and correlated with [Na/Fe] and [Si/Fe]. These relations are not continuous in nature, but the distribution of stars is clearly clustered around three distinct Al values, low, intermediate, and high. These three groups nicely correspond to the three distinct sequences previously detected using Stromgren photometry along the red giant branch. These two independent findings strongly indicate the existence of three distinct stellar populations in NGC 6752. Comparing the abundances of O and Mg, we find that the population with intermediate chemical abundances cannot originate from material with the same composition of the most O- and Mg-poor population, diluted by material with that of the most O- and Mg-ri...

  20. Heavy elements Ba, La, Ce, Nd, and Eu in 56 Galactic bulge red giants

    CERN Document Server

    Van der Swaelmen, M; Hill, V; Zoccali, M; Minniti, D; Ortolani, S; Gomez, A

    2016-01-01

    Aims. The aim of this work is the study of abundances of the heavy elements Ba, La, Ce, Nd, and Eu in 56 bulge giants (red giant branch and red clump) with metallicities ranging from -1.3 dex to 0.5 dex. Methods. We obtained high-resolution spectra of our giant stars using the FLAMES-UVES spectrograph on the Very Large Telescope. We inspected four bulge fields along the minor axis. Results. We measure the chemical evolution of heavy elements, as a function of metallicity, in the Galactic bulge. Conclusions. The [Ba, La, Ce, Nd/Fe] vs. [Fe/H] ratios decrease with increasing metallicity, in which aspect they differ from disc stars. In our metal-poor bulge stars, La and Ba are enhanced relative to their thick disc counterpart, while in our metal-rich bulge stars La and Ba are underabundant relative to their disc counterpart. Therefore, this contrast between bulge and discs trends indicates that bulge and (solar neighbourhood) thick disc stars could behave differently. An increase in [La, Nd/Eu] with increasing m...

  1. The role of preoperative angiography in the management of giant meningiomas associated to vascular malformation

    Directory of Open Access Journals (Sweden)

    Fabio Papacci

    2015-01-01

    Full Text Available Background: The role of preoperative digital subtraction angiography (DSA in meningiomas is currently under discussion because of the introduction of noninvasive magnetic resonance imaging (MRI angiography to study vascular anatomy associated to the tumor. Preoperative DSA is mainly performed to obtain embolization of the lesion, although a number of complications have been reported after this procedure. Nonetheless, the coexistence of meningiomas with vascular malformations has previously been reported and it has been evidenced that this event could be underestimated because of neglect of preoperative DSA. Here, we report on two challenging cases of giant meningiomas associated to vascular malformations and we discuss the pertinent literature. Case Descriptions: In the first case: A large right temporal meningioma with erosion of the sphenoid greater wing and extension toward infratemporal fossa and right orbit - a large pseudoaneurysm of right middle cerebral artery branch was found end embolized during DSA. In the second case: A giant parieto-temporal meningioma - DSA permitted the full visualization of an abnormal drainage of superior sagittal sinus like a "sinus pericranii" that was respected during the following surgery. Conclusion: We think that MRI angiography is the exam of choice to study vascular anatomy in meningiomas. Nonetheless, DSA remains a useful tool in giant meningiomas not only to embolizate the lesion but also to treat tumor associated vascular malformation and to achieve the full knowledge of vascular anatomy. We think that a wide communication between interventionalist and surgeon is essential for the optimal management of these patients.

  2. Soils of Walker Branch Watershed

    Energy Technology Data Exchange (ETDEWEB)

    Lietzke, D.A.

    1994-01-01

    The soil survey of Walker Branch Watershed (WBW) utilized the most up-to-date knowledge of soils, geology, and geohydrology in building the soils data base needed to reinterpret past research and to begin new research in the watershed. The soils of WBW were also compared with soils mapped elsewhere along Chestnut Ridge on the Oak Ridge Reservation to (1) establish whether knowledge obtained elsewhere could be used within the watershed, (2) determine whether there were any soils restricted to the watershed, and (3) evaluate geologic formation lateral variability. Soils, surficial geology, and geomorphology were mapped at a scale of 1:1200 using a paper base map having 2-ft contour intervals. Most of the contours seemed to reasonably represent actual landform configurations, except for dense wooded areas. For example, the very large dolines or sinkholes were shown on the contour base map, but numerous smaller ones were not. In addition, small drainageways and gullies were often not shown. These often small but important features were located approximately as soil mapping progressed. WBW is underlain by dolostones of the Knox Group, but only a very small part of the surface area contains outcroppings of rock and most outcrops were located in the lower part. Soil mapping revealed the presence of both ancient alluvium and ancient colluvium deposits, not recognized in previous soil surveys, that have been preserved in high-elevation stable portions of present-day landforms. An erosional geomorphic process of topographic inversion requiring several millions of years within the Pleistocene is necessary to bring about the degree of inversion that is expressed in the watershed. Indeed, some of these ancient alluvial and colluvial remnants may date back into the Tertiary. Also evident in the watershed, and preserved in the broad, nearly level bottoms of dolines, are multiple deposits of silty material either devoid or nearly devoid of coarse fragments. Recent research

  3. The Novel Y-Branch With Two Reflectors

    Institute of Scientific and Technical Information of China (English)

    Ruei-Chang Lu; Yu-Pin Liao

    2003-01-01

    A novel Y-branch waveguide with two reflectors is proposed. The normalized transmitted power for the branching angle of 50°is greater than 70%, which is higher than conventional Y-branch with such wide angle.

  4. Perivascular exudates in frosted branch angiitis.

    Science.gov (United States)

    He, Lingmin; Moshfeghi, Darius M; Wong, Ira G

    2014-01-01

    Three cases of young, minimally symptomatic patients found to have vitritis and extensive perivenous vitreous exudates resembling frosted branch angiitis are presented. Optical coherence tomography showed that these exudates appear to be extravascated from the vasculature. The material persisted over 1 year on immunosuppressive therapy, suggesting that its resolution should not be a treatment end point. These cases add to our understanding of the spectrum of clinical findings in frosted branch angiitis.

  5. Branch retinal artery occlusion in Susac's syndrome

    Directory of Open Access Journals (Sweden)

    Ricardo Evangelista Marrocos de Aragão

    2015-02-01

    Full Text Available Susac's syndrome is a rare disease attribuited to a microangiopathy involving the arterioles of the cochlea, retina and brain. Encefalopathy, hearing loss, and visual deficits are the hallmarks of the disease. Visual loss is due to multiple, recurrent branch arterial retinal occlusions. We report a case of a 20-year-old women with Susac syndrome presented with peripheral vestibular syndrome, hearing loss, ataxia, vertigo, and vision loss due occlusion of the retinal branch artery.

  6. CAST Xi'an Branch Established

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ China Academy of Space Technology (CAST) Xi'an Branch was established on April 8,2008.The new branch consists of the headquarters of the former Xi'an Institute of Space Radio Technology (XISRT) of CAST and five former subsidiaries of the XISRT,i.e.the Institute of Space Electronic Technology,the Institute of Microwave Technology,the Institute of Space Antenna Technology,the Manufacturing Center for Space Electronics and Civilian High-tech Company.

  7. $\\tau$ hadronic branching ratios at DELPHI

    CERN Document Server

    Humble, Stephen

    1999-01-01

    Using data collected in the DELPHI detector at LEP1, we have measured the exclusive branching ratios in modes with several hadrons. Both classical cuts and neural network methods have been performed to make the best use of the DELPHI neutral particle identification capability. In addition, a measurement of inclusive branching ratios for tau decays containing one or three charged particles has been performed. (4 refs).

  8. Parton Branching in Color Mutation Model

    CERN Document Server

    Hwa, R C

    1999-01-01

    The soft production problem in hadronic collisions as described in the eikonal color mutation branching model is improved in the way that the initial parton distribution is treated. Furry branching of the partons is considered as a means of describing the nonperturbative process of parton reproduction in soft interaction. The values of all the moments, and $C_q$, for q=2,...,5, as well as their energy dependences can be correctly determined by the use of only two parameters.

  9. All change at the CERN UBS branch

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    UBS branches across the country are being modernised, and the CERN branch is no exception. The Bulletin brings you a preview of the project, which will get under way in January 2013.   Mock-up of the renovated UBS branch. The changes at the UBS branch in CERN's Main Building will be no simple facelift. The entire bank will be renovated, transforming the present relatively confined premises into an open and attractive area. "The renovation of the UBS branches is part of a wider campaign designed to further enhance our customer relations," explains Ezio Mangia, the head of the CERN branch.  The UBS bank currently occupies three sets of premises in CERN's Main Building (two on the ground floor and one in the basement). "By the end of the work, which is scheduled to be completed by the middle of next year, CERN customers will benefit from a new area with open-plan counters and "hole-in-the-wall" machines accessible to...

  10. Terminal Branch of Recurrent Human Laryngeal Nerve

    Directory of Open Access Journals (Sweden)

    Andréa Aparecida Ferreira Pascoal

    2014-01-01

    Full Text Available The importance of the recurrent laryngeal nerve in surgery on the anterior region of the neck has motivated many published papers on critical points of its pathway, relationship with the inferior thyroid artery, penetration in the larynx, division outside the larynx, and branches communicating with the internal branch of the superior laryngeal nerve. We analyze the terminal branches of the recurrent laryngeal nerve and their distribution through the laryngeal muscles. 44 laryngeal nerves had been dissected. Most frequently, the recurrent laryngeal nerve presents a division below or at the level of the lower margin of the cricoid cartilage (outside the larynx. One of these branches forms the communication with the internal branch of the superior laryngeal nerve, and the other penetrates the laryngeal space. Above the lower margin of the cricoid cartilage, the inferior laryngeal nerve issues a variable number of branches to muscles (3 to 7: to the posterior cricoarytenoid muscle; to the oblique and transversal arytenoid muscles; and to the lateral cricoarytenoid muscle and the thyroarytenoid muscle.

  11. NRAGE: a potential rheostat during branching morphogenesis.

    Science.gov (United States)

    Nikopoulos, George N; Martins, Joao Ferreira; Adams, Tamara L; Karaczyn, Aldona; Adams, Derek; Vary, Calvin; Oxburgh, Leif; Verdi, Joseph M

    2009-01-01

    Branching morphogenesis is a developmental process characteristic of many organ systems. Specifically, during renal branching morphogenesis, its been postulated that the final number of nephrons formed is one key clinical factor in the development of hypertension in adulthood. As it has been established that BMPs regulate, in part, renal activity of p38 MAP kinase (p38(MAPK)) and it has demonstrated that the cytoplasmic protein Neurotrophin Receptor MAGE homologue (NRAGE) augments p38(MAPK) activation, it was hypothesized that a decrease in the expression of NRAGE during renal branching would result in decreased branching of the UB that correlated with changes in p38(MAPK) activation. To verify this, the expression of NRAGE was reduced in ex vivo kidney explants cultures using antisense morpholino. Morpholino treated ex vivo kidney explants expression were severely stunted in branching, a trait that was rescued with the addition of exogenous GDNF. Renal explants also demonstrated a precipitous drop in p38(MAPK) activation that too was reversed in the presence of recombinant GDNF. RNA profiling of NRAGE diminished ex vivo kidney explants resulted in altered expression of GDNF, Ret, BMP7 and BMPRIb mRNAs. Our results suggested that in early kidney development NRAGE might have multiple roles during renal branching morphogenesis through association with both the BMP and GDNF signaling pathways.

  12. Giant cell tumor in adipose package Hoffa

    Science.gov (United States)

    Etcheto, H. Rivarola; Escobar, G.; Blanchod, C. Collazo; Palanconi, M.; Zordan, J.; Salinas, E. Alvarez; Autorino₁, Carlos

    2017-01-01

    Tumors of adipose Hoffa package are very uncommon, with isolated cases reported in the literature. His presentation in pediatric patients knee is exceptional. The most frequently described tumors are benign including vellonodular synovitis. The extra-articular localized variant there of is known as giant cell tumor of the tendon sheath. It is characterized by locally aggressive nature, and has been described in reports of isolated cases. Objective: A case of giant cell tumor of the tendon sheath in adipose presentation package Hoffa in pediatric patients is presented in this paper. Methods: male patient eleven years with right knee pain after sports practice was evaluated. Physical examination, showed limited extension -30º, joint effusion, stable negative Lachman maneuver without peripheral knee laxity. MRI hyperintense on tumor is observed in T2 and hypointense on T1 homogeneous and defined edges content displayed prior to LCA related to adipose Hoffa package. Results: The tumor specimen was obtained and histopathology is defined as densely cellular tissue accumulation of xantomisados fibrocollagenous with histiocytes and multinucleated giant cells, compatible with giant cell tumor of tendon sheath. Conclusion: The presentation of giant cell tumors of the tendon sheath in Hoffa fat pad is exceptional. However, his suspicion allows adequate preoperative surgical planning, as a whole resection is the only procedure that has been shown to decrease the rate of recurrence of this disease.

  13. Infrared spectral properties of M giants

    CERN Document Server

    Sloan, G C; Ramirez, R M; Kraemer, K E; Engelke, C W

    2015-01-01

    We observed a sample of 20 M giants with the Infrared Spectrograph on the Spitzer Space Telescope. Most show absorption structure at 6.6-6.8 um which we identify as water vapor, and in some cases, the absorption extends from 6.4 um into the SiO band at 7.5 um. Variable stars show stronger H2O absorption. While the strength of the SiO fundamental at 8 um increases monotonically from spectral class K0 to K5, the dependence on spectral class weakens in the M giants. As with previously studied samples, the M giants show considerable scatter in SiO band strength within a given spectral class. All of the stars in our sample also show OH band absorption, most noticeably in the 14-17 um region. The OH bands behave much like the SiO bands, increasing in strength in the K giants but showing weaker dependence on spectral class in the M giants, and with considerable scatter. An examination of the photometric properties reveals that the V-K color may be a better indicator of molecular band strength than the spectral class...

  14. An MHD model for magnetar giant flares

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Y.; Lin, J.; Zhang, Q. S. [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011 (China); Zhang, L. [Department of Physics, Yunnan University, Kunming, Yunnan 650091 (China); Reeves, K. K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yuan, F., E-mail: mengy@ynao.ac.cn, E-mail: jlin@ynao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2014-04-10

    Giant flares on soft gamma-ray repeaters that are thought to take place on magnetars release enormous energy in a short time interval. Their power can be explained by catastrophic instabilities occurring in the magnetic field configuration and the subsequent magnetic reconnection. By analogy with the coronal mass ejection events on the Sun, we develop a theoretical model via an analytic approach for magnetar giant flares. In this model, the rotation and/or displacement of the crust causes the field to twist and deform, leading to flux rope formation in the magnetosphere and energy accumulation in the related configuration. When the energy and helicity stored in the configuration reach a threshold, the system loses its equilibrium, the flux rope is ejected outward in a catastrophic way, and magnetic reconnection helps the catastrophe develop to a plausible eruption. By taking SGR 1806–20 as an example, we calculate the free magnetic energy released in such an eruptive process and find that it is more than 10{sup 47} erg, which is enough to power a giant flare. The released free magnetic energy is converted into radiative energy, kinetic energy, and gravitational energy of the flux rope. We calculated the light curves of the eruptive processes for the giant flares of SGR 1806–20, SGR 0526–66, and SGR 1900+14, and compared them with the observational data. The calculated light curves are in good agreement with the observed light curves of giant flares.

  15. Surface rotation of Kepler red giant stars

    Science.gov (United States)

    Ceillier, T.; Tayar, J.; Mathur, S.; Salabert, D.; García, R. A.; Stello, D.; Pinsonneault, M. H.; van Saders, J.; Beck, P. G.; Bloemen, S.

    2017-09-01

    Kepler allows the measurement of starspot variability in a large sample of field red giants for the first time. With a new method that combines autocorrelation and wavelet decomposition, we measure 361 rotation periods from the full set of 17 377 oscillating red giants in our sample. This represents 2.08% of the stars, consistent with the fraction of spectroscopically detected rapidly rotating giants in the field. The remaining stars do not show enough variability to allow us to measure a reliable surface rotation period. Because the stars with detected rotation periods have measured oscillations, we can infer their global properties, e.g. mass and radius, and quantitatively evaluate the predictions of standard stellar evolution models as a function of mass. Consistent with results for cluster giants when we consider only the 4881 intermediate-mass stars, M > 2.0 M⊙ from our full red giant sample, we do not find the enhanced rates of rapid rotation expected from angular momentum conservation. We therefore suggest that either enhanced angular momentum loss or radial differential rotation must be occurring in these stars. Finally, when we examine the 575 low-mass (Mhttp://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A111

  16. Electrodynamics on extrasolar giant planets

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, T. T.; Yelle, R. V. [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721-0092 (United States); Lavvas, P. [Groupe de Spectroscopie Moléculaire et Atmosphérique UMR CNRS 7331, Université Reims Champagne-Ardenne, F-51687 Reims (France); Cho, J. Y-K., E-mail: tommi@lpl.arizona.edu [Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)

    2014-11-20

    Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter the energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially

  17. Anaplastic giant cell thyroid carcinoma.

    Science.gov (United States)

    Wallin, G; Lundell, G; Tennvall, J

    2004-01-01

    Anaplastic (giant cell) thyroid carcinoma (ATC), is one of the most aggressive malignancies in humans with a median survival time after diagnosis of 3-6 months. Death from ATC was earlier seen because of local growth and suffocation. ATC is uncommon, accounting for less than 5 % of all thyroid carcinomas. The diagnosis can be established by means of multiple fine needle aspiration biopsies, which are neither harmful nor troublesome for the patient. The cytological diagnosis of this high-grade malignant tumour is usually not difficult for a well trained cytologist. The intention to treat patients with ATC is cure, although only few of them survive. The majority of the patients are older than 60 years and treatment must be influenced by their high age. We have by using a combined modality regimen succeeded in achieving local control in most patients. Every effort should be made to control the primary tumour and thereby improve the quality of remaining life and it is important for patients, relatives and the personnel to know that cure is not impossible. Different treatment combinations have been used since 30 years including radiotherapy, cytostatic drugs and surgery, when feasible. In our latest combined regimen, 22 patients were treated with hyper fractionated radiotherapy 1.6Gy x 2 to a total target dose of 46 Gy given preoperatively, 20 mg doxorubicin was administered intravenously once weekly and surgery was carried out 2-3 weeks after the radiotherapy. 17 of these 22 patients were operated upon and none of these 17 patients got a local recurrence. In the future we are awaiting the development of new therapeutic approaches to this aggressive type of carcinoma. Inhibitors of angiogenesis might be useful. Combretastatin has displayed cytotoxicity against ATC cell lines and has had a positive effect on ATC in a patient. Sodium iodide symporter (NIS) genetherapy is also being currently considered for dedifferentiated thyroid carcinomas with the ultimate aim of

  18. Mixing processes during the evolution of red giants with moderate metal deficiencies the role of molecular-weight barriers

    CERN Document Server

    Charbonnel, C; Wallerstein, G; Charbonnel, Corinne; Brown, Jeffery A.; Wallerstein, George

    1997-01-01

    We have assembled accurate abundance data for Li, C, and N as well as the 12C/13C ratio for five field giants with [Fe/H]=-0.6 including Arcturus and two stars in the globular cluster 47 Tuc. Using their very precise Mbol values obtained from HIPPARCOSparallaxes, we can place them into an evolutionary sequence. The sequence shows that the 12C/13C ratios ratios drops from 20 to near 7 between Mbol=+1 and +0.5, while Li disappears. At the same time the 12C/14N ratio diminishes by 0.2 to 0.4 dex. The two stars in 47 Tuc with Mbol near -2.0 show even lower 12C14N ratios by 0.4 dex indicating further mixing as they evolved to the top of the red giant branch. These observations confirm the existence of an extra-mixing process that becomes efficient on the red giant branch only when the low-mass stars reach the so-called luminosity function bump. We use the values of the carbon isotopic ratio observed in our sample to get constraints on the mu-barriers that may shield the central regions of a star from extra-mixing....

  19. Ether- versus ester-linked phospholipid bilayers containing either linear or branched apolar chains.

    Science.gov (United States)

    Balleza, Daniel; Garcia-Arribas, Aritz B; Sot, Jesús; Ruiz-Mirazo, Kepa; Goñi, Félix M

    2014-09-16

    We studied the properties of bilayers formed by ether-and ester-containing phospholipids, whose hydrocarbon chains can be either linear or branched, using sn-1,2 dipalmitoyl, dihexadecyl, diphytanoyl, and diphytanyl phosphatidylcholines (DPPC, DHPC, DPhoPC, and DPhPC, respectively) either pure or in binary mixtures. Differential scanning calorimetry and confocal fluorescence microscopy of giant unilamellar vesicles concurred in showing that equimolar mixtures of linear and branched lipids gave rise to gel/fluid phase coexistence at room temperature. Mixtures containing DHPC evolved in time (0.5 h) from initial reticulated domains to extended solid ones when an equilibrium was achieved. The nanomechanical properties of supported planar bilayers formed by each of the four lipids studied by atomic force microscopy revealed average breakdown forces Fb decreasing in the order DHPC ≥ DPPC > DPhoPC > DPhPC. Moreover, except for DPPC, two different Fb values were found for each lipid. Atomic force microscopy imaging of DHPC was peculiar in showing two coexisting phases of different heights, probably corresponding to an interdigitated gel phase that gradually transformed, over a period of 0.5 h, into a regular tilted gel phase. Permeability to nonelectrolytes showed that linear-chain phospholipids allowed a higher rate of solute + water diffusion than branched-chain phospholipids, yet the former supported a smaller extent of swelling of the corresponding vesicles. Ether or ester bonds appeared to have only a minor effect on permeability.

  20. An HST/WFC3 view of stellar populations on the Horizontal Branch of NGC 2419

    CERN Document Server

    Di Criscienzo, M; Milone, A P; D'Antona, F; Ventura, P; Dotter, A; Brocato, E

    2015-01-01

    We use images acquired with the Hubble Space Telescope Wide Field Camera 3 and new models to probe the Horizontal Branch (HB) population of the We use images acquired with the Hubble Space Telescope Wide Field Camera 3 and new models to probe the horizontal branch (HB) population of the Galactic globular cluster (GC) NGC 2419. A detailed analysis of the composite HB highlights three populations:(1) the blue luminous HB, hosting standard helium stars (Y=0.25) with a very small spread of mass, (2) a small population of stars with intermediate helium content (0.26giant branch (AGB) stars of the same metallicity as NGC 2419. Thi...

  1. Giant cell arteritis. Part I. Terminology, classification, clinical manifestations, diagnosis

    Directory of Open Access Journals (Sweden)

    Azamat Makhmudovich Satybaldyev

    2012-01-01

    Full Text Available Giant cell arteritis (GCA is a vasculitis affecting mainly large and medium-sized arteries, which the classification of systemic vasculitides refers to as those mainly involving the large vessels. GCA is typified by the involvement of extracranial aortic branches and intracranial vessels, the aorta and its large vessels are being affected most frequently. The paper considers the terminology, classification, prevalence, major pathogenic mechanisms, and morphology of GCA. A broad spectrum of its clinical subtypes is due to target vessel stenosis caused by intimal hyperplasia. In 40% of cases, GCA is shown to be accompanied by polymyalgia rheumatica that may either precede or manifest simultaneously with GCA, or follow this disease. The menacing complications of GCA may be visual loss or ischemic strokes at various sites depending on the location of the occluded vessel. Along with the gold standard verification of the diagnosis of GCA, namely temporal artery biopsy, the author indicates other (noninvasive methods for detection of vascular lesions: color Doppler ultrasonography of the temporal arteries, fluorescein angiography of the retina, mag-netic resonance angiography, magnetic resonance imaging, and computed tomography to rule out aortic aneurysm. Dynamic 18F positron emission tomography is demonstrated to play a role in the evaluation of therapeutic effectiveness.

  2. The Keck Aperture Masking Experiment: Dust Enshrouded Red Giants

    CERN Document Server

    Blasius, T D; Tuthill, P G; Danchi, W C; Anderson, M

    2012-01-01

    While the importance of dusty asymptotic giant branch (AGB) stars to galactic chemical enrichment is widely recognised, a sophisticated understanding of the dust formation and wind-driving mechanisms has proven elusive due in part to the difficulty in spatially-resolving the dust formation regions themselves. We have observed twenty dust-enshrouded AGB stars as part of the Keck Aperture Masking Experiment, resolving all of them in multiple near-infrared bands between 1.5 microns and 3.1 microns. We find 45% of the targets to show measurable elongations that, when correcting for the greater distances of the targets, would correspond to significantly asymmetric dust shells on par with the well-known cases of IRC+10216 or CIT6. Using radiative transfer models, we find the sublimation temperature of 1130 +- 90 K and 1170 +- 60 K for silicates and amorphous carbon respectively, both somewhat lower than expected from laboratory measurements and vastly below temperatures inferred from the inner edge of YSO disks. Th...

  3. Giant Uterine Leiomyoma. A Case Report

    Directory of Open Access Journals (Sweden)

    Luis Noel Marrero Quiala

    2014-09-01

    Full Text Available Giant uterine fibromyoma is a benign condition which has a very low incidence. Its management poses a challenge for the surgical team due to the volume of the surgical specimen and the variations in the distribution of the intra-abdominal organs caused by the uterine growth. The case of a 29-year-old patient misdiagnosed with giant hepatomegaly at admission is presented. Her symptoms included hard abdomen and feeling of heaviness. Successful completion of the interview, physical examination and imaging studies led to the correct diagnosis of giant uterine fibromyoma. Surgical treatment was applied. A total abdominal hysterectomy was performed with satisfactory results. This case is presented to the medical community for teaching purposes and due to its rarity.

  4. Red-giant stars in eccentric binaries

    Directory of Open Access Journals (Sweden)

    Beck P. G.

    2015-01-01

    Full Text Available The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs.

  5. Trace Molecules in Giant Planet Atmospheres

    Science.gov (United States)

    Huestis, D. L.; Smith, G. P.

    2010-12-01

    Chemical kinetics matters in the upper atmospheres of giant planets in our solar system and in extrasolar systems. The composition of a volume of gas depends not only on where it is, but also on how it got there. The giant planets in our own solar system still have much to teach us about what we will be observing on extrasolar giant planets and how to interpret what we observe. Some molecules, such as CO, C2H2, C2H6, PH3, and NH3, which we call tracer molecules, provide remotely observable signatures of vertical transport. PH3 and NH3 especially have complicated thermochemistry and chemical kinetics that, until recently, have been poorly understood. Based on analysis of recent literature, we have identified new chemical mechanisms for interconverting NH3 and N2 and for interconverting PH3 and NH4-H2PO4.

  6. Observations of Radio Giant Pulses with GAVRT

    CERN Document Server

    Jones, Glenn

    2015-01-01

    Radio giant pulses provide a unique opportunity to study the pulsar radio emission mechanism in exquisite detail. Previous studies have revealed a wide range of properties and phenomena, including extraordinarily high brightness temperatures, sub-nanosecond emission features, and banded dynamic spectra. New measurements of giant pulse characteristics can help guide and test theoretical emission models. To this end, an extensive observation campaign has begun which will provide more than 500 hours on the Crab with a 34-meter antenna located in California, USA. The observations are being done as part of an educational outreach program called the Goldstone-Apple Valley Radio Telescope (GAVRT). This antenna has a novel wide bandwidth receiver which provides up to 8 GHz of instantaneous bandwidth in the range of 2.5 to 14 GHz. These observations will provide detailed information about the variability, amplitude distribution, and detailed frequency structure of radio giant pulses. In addition, a database of pulses ...

  7. Giant Uterine Leiomyoma. A Case Report

    Directory of Open Access Journals (Sweden)

    Luis Noel Marrero Quiala

    2014-09-01

    Full Text Available Giant uterine fibromyoma is a benign condition which has a very low incidence. Its management poses a challenge for the surgical team due to the volume of the surgical specimen and the variations in the distribution of the intra-abdominal organs caused by the uterine growth. The case of a 29-year-old patient misdiagnosed with giant hepatomegaly at admission is presented. Her symptoms included hard abdomen and feeling of heaviness. Successful completion of the interview, physical examination and imaging studies led to the correct diagnosis of giant uterine fibromyoma. Surgical treatment was applied. A total abdominal hysterectomy was performed with satisfactory results. This case is presented to the medical community for teaching purposes and due to its rarity.

  8. Hepatic Giant Cell Arteritis and Polymyalgia Rheumatica

    Directory of Open Access Journals (Sweden)

    Donald R Duerksen

    1994-01-01

    Full Text Available Polymyalgia rheumatica (PMR is a clinical syndrome of the elderly characterized by malaise, proximal muscle aching and stiffness, low grade fever, elevated erythrocyte sedimentation rare and the frequent association with temporal giant cell arteritis. The authors describe a case of PMR associated with hepatic giant cell arteritis. This lesion has been described in two other clinical reports. The distribution of the arteritis may be patchy; in this report, diagnosis was made with a wedge biopsy performed after an initial nonspecific percutaneous liver biopsy. The authors review the spectrum of liver involvement in PMR and giant cell arteritis. Hepatic abnormalities respond to systemic corticosteroids, and patients with hepatic arteritis have a good prognosis.

  9. Asymptomatic post-rheumatic giant left atrium.

    Science.gov (United States)

    Özkartal, Tardu; Tanner, Felix C; Niemann, Markus

    2016-06-26

    A 78-year-old asymptomatic woman was referred to our clinic for a second opinion regarding indication for mitral valve surgery. An echocardiogram showed a moderate mitral stenosis with a concomitant severe regurgitation. The most striking feature, however, was a giant left atrium with a parasternal anteroposterior diameter of 79 mm and a left atrial volume index of 364 mL/m². There are various echocardiographic definitions of a giant left atrium, which are mainly based on measurements of the anteroposterior diameter of the left atrium using M-mode in the parasternal long axis view. Since the commonly accepted method for echocardiographic evaluation of left atrial size is left atrial volume index, we propose a cut-off value of 140 mL/m(2) for the definition of a "giant left atrium".

  10. Giant repeater F-wave in patients with anterior horn cell disorders. Role of motor unit size.

    Science.gov (United States)

    Ibrahim, I K; el-Abd, M A

    1997-01-01

    Conventional F-wave responses as well as single motor unit F-wave responses together with the volitionally recruited motor unit action potentials (MUAP) were studied in hand and feet muscles of 10 healthy subjects and 32 patients with anterior horn cell disorders. The amplitude of the largest F-wave (Fl) was significantly greater in the affected patients compared with healthy subjects. Giant repeater F-wave responses "up to 4 mV" were recorded in muscles having volitionally recruited giant MUAPs. Although, the group mean percentage of motor unit F-wave responses per stimulation in all tested orthodromic MUAPs was significantly decreased in amyotrophic lateral sclerosis patients, the group mean percentage of motor unit F-wave responses per stimulation in all tested orthodromic MUAPs that gave motor unit F-wave response was significantly increased compared with healthy subjects. The responding orthodromic MUAP gave identical motor unit F-wave response, even for complex polyphasic units. Enhanced monosynaptic (H-) reflex, proximal axon reflex (A-wave), and repetitive muscle response as possible explanations for the giant F-wave responses could be discounted. The electrophysiologic behavior of the giant late responses described here fits well with the criteria of F-waves modulated by newly formed distal (and or proximal) axonal branching.

  11. The UK Infrared Telescope M33 monitoring project. IV. Variable red giant stars across the galactic disc

    CERN Document Server

    Javadi, Atefeh; van Loon, Jacco Th; Khosroshahi, Habib; Golabatooni, Najmeh; Mirtorabi, Mohammad Taghi

    2014-01-01

    We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this fourth paper of the series, we present a search for variable red giant stars in an almost square degree region comprising most of the galaxy's disc, carried out with the WFCAM instrument in the K band. These data, taken during the period 2005--2007, were complemented by J- and H-band images. Photometry was obtained for 403 734 stars in this region; of these, 4643 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. The variable stars are concentrated towards the centre of M33, more so than low-mass, less-evolved red giants. Our data were matched to optical catalogues of variable stars and ca...

  12. The Orbital Nature of 81 Ellipsoidal Red Giant Binaries in the Large Magellanic Cloud

    Science.gov (United States)

    Nie, J. D.; Wood, P. R.; Nicholls, C. P.

    2017-02-01

    In this paper, we collect a sample of 81 ellipsoidal red giant binaries in the Large Magellanic Cloud (LMC), and we study their orbital natures individually and statistically. The sample contains 59 systems with circular orbits and 22 systems with eccentric orbits. We derive orbital solutions using the 2010 version of the Wilson–Devinney code. The sample is selection-bias corrected, and the orbital parameter distributions are compared to model predictions for the LMC and to observations in the solar vicinity. The masses of the red giant primaries are found to range from about 0.6 to 9 {M}ȯ with a peak at around 1.5 {M}ȯ , in agreement with studies of the star formation history of the LMC, which find a burst of star formation beginning around 4 Gyr ago. The observed distribution of mass ratios q={m}2/{m}1 is more consistent with the flat q distribution derived for the solar vicinity by Raghavan et al. than it is with the solar vicinity q distribution derived by Duquennoy & Mayor. There is no evidence for an excess number of systems with equal mass components. We find that about 20% of the ellipsoidal binaries have eccentric orbits, twice the fraction estimated by Soszynski et al. Our eccentricity evolution test shows that the existence of eccentric ellipsoidal red giant binaries on the upper parts of the red giant branch (RGB) can only be explained if tidal circularization rates are ∼1/100 the rates given by the usual theory of tidal dissipation in convective stars.

  13. Neglected Giant Scalp Basal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Anne Kristine Larsen, MD

    2014-03-01

    Full Text Available Summary: Rarely, basal cell carcinoma grows to a giant size, invading the underlying deep tissue and complicating the treatment and reconstruction modalities. A giant basal cell carcinoma on the scalp is in some cases treated with a combination of surgery and radiation therapy, resulting in local control, a satisfactory long-term cosmetic and functional result. We present a case with a neglected basal cell scalp carcinoma, treated with wide excision and postoperative radiotherapy, reconstructed with a free latissimus dorsi flap. The cosmetic result is acceptable and there is no sign of recurrence 1 year postoperatively.

  14. Mass loss from giant and supergiant stars

    Science.gov (United States)

    Wannier, P. G.; Sahai, R.

    1986-01-01

    The 12 m telescope of the National Radio Astronomy Observatory has been used at the J = 2-1 transition of CO to increase the known list of giant and supergiant stars with observable circumstellar envelopes. The candidate objects were generally M-type giants and supergiants, chosen for their strong infrared luminosities. Of the 35 objects which were previously undetected, or only marginally detected, 10 were found to produce detectable CO emission. Physical parameters of the envelopes are derived by source modeling. Mass-loss rates vary from 10 to the -7th to 4 x 10 to the -5th solar mass/yr.

  15. Enhanced recovery after giant ventral hernia repair

    DEFF Research Database (Denmark)

    Jensen, K K; Brøndum, T L; Harling, H.

    2016-01-01

    PURPOSE: Giant ventral hernia repair is associated with a high risk of postoperative morbidity and prolonged length of stay (LOS). Enhanced recovery (ERAS) measures have proved to lead to decreased morbidity and LOS after various surgical procedures, but never after giant hernia repair. The current....... Pain, nausea and fatigue were registered prospectively in all patients treated according to ERAS, as well as continuous measurement of transcutaneous capillary oxygen saturation. Postoperative morbidity and LOS were compared between patients treated according to ERAS and a historic group treated...

  16. Kepler Asteroseismology of Red-giant Stars

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J.

    2012-01-01

    The Kepler mission, launched in March 2009, has revolutionized asteroseismology, providing detailed observations of thousands of stars. This has allowed in-depth analyses of stars ranging from compact hot subdwarfs to red giants, and including the detection of solar-like oscillations in hundreds...... of stars on or near the main sequence. Here I mainly consider solar-like oscillations in red giants, where Kepler observations are yielding results of a perhaps unexpected richness. In addition to giving a brief overview of the observational and numerical results for these stars, I present a simple...

  17. Neglected giant scalp Basal cell carcinoma

    DEFF Research Database (Denmark)

    Larsen, Anne Kristine; El-Charnoubi, Waseem-Asim Ghulam; Gehl, Julie;

    2014-01-01

    SUMMARY: Rarely, basal cell carcinoma grows to a giant size, invading the underlying deep tissue and complicating the treatment and reconstruction modalities. A giant basal cell carcinoma on the scalp is in some cases treated with a combination of surgery and radiation therapy, resulting in local...... control, a satisfactory long-term cosmetic and functional result. We present a case with a neglected basal cell scalp carcinoma, treated with wide excision and postoperative radiotherapy, reconstructed with a free latissimus dorsi flap. The cosmetic result is acceptable and there is no sign of recurrence...

  18. Structure-Property Relationships for Branched Worm-Like Micelles

    Science.gov (United States)

    Beaucage, Gregory; Rai, Durgesh

    2013-03-01

    Micellar solutions can display a wide range of phase structure as a function of counter ion content, surfactant concentration, and the presence of ternary components. Under some conditions, common to consumer products, extended cylindrical structures that display persistence and other chain features of polymers are produced. These worm-like micelles (WLMs) can form branched structures that dynamically change under shear and even in quiescent conditions. The rheology of these branched WLMs is strongly dependent on migration of the branch points, and the dynamics of branch formation and removal. Persistence and other polymer-based descriptions are also of importance. We have recently developed a scattering model for branched polyolefins and other topologically complex materials that can quantify the branching density, branch length, branch functionality and the hyperbranch (branch-on-branch) content of polymers. This work is being extended to study branching in WLMs in work coupled with Ron Larson at UMich to predict rheological properties.

  19. MAPPING DIRECTLY IMAGED GIANT EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Kostov, Veselin [Department of Physics and Astronomy, Johns Hopkins University, 366 Bloomberg Center, 3400 North Charles Street, Baltimore, MD 21218 (United States); Apai, Daniel, E-mail: vkostov@pha.jhu.edu [Department of Astronomy, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85718 (United States)

    2013-01-01

    With the increasing number of directly imaged giant exoplanets, the current atmosphere models are often not capable of fully explaining the spectra and luminosity of the sources. A particularly challenging component of the atmosphere models is the formation and properties of condensate cloud layers, which fundamentally impact the energetics, opacity, and evolution of the planets. Here we present a suite of techniques that can be used to estimate the level of rotational modulations these planets may show. We propose that the time-resolved observations of such periodic photometric and spectroscopic variations of extrasolar planets due to their rotation can be used as a powerful tool to probe the heterogeneity of their optical surfaces. In this paper, we develop simulations to explore the capabilities of current and next-generation ground- and space-based instruments for this technique. We address and discuss the following questions: (1) what planet properties can be deduced from the light curve and/or spectra, and in particular can we determine rotation periods, spot coverage, spot colors, and spot spectra?; (2) what is the optimal configuration of instrument/wavelength/temporal sampling required for these measurements?; and (3) can principal component analysis be used to invert the light curve and deduce the surface map of the planet? Our simulations describe the expected spectral differences between homogeneous (clear or cloudy) and patchy atmospheres, outline the significance of the dominant absorption features of H{sub 2}O, CH{sub 4}, and CO, and provide a method to distinguish these two types of atmospheres. Assuming surfaces with and without clouds for most currently imaged planets the current models predict the largest variations in the J band. Simulated photometry from current and future instruments is used to estimate the level of detectable photometric variations. We conclude that future instruments will be able to recover not only the rotation periods

  20. 富锂巨星的观测研究%Observation of Lithium-rich Giants

    Institute of Scientific and Technical Information of China (English)

    符晓婷; 邓李才; Kirby Evan N; Guhathakurta Puragra

    2012-01-01

    锂在温度达到T>2.5×106 K时即参与7Li(p,α)4He反应燃烧,经典恒星理论推测,当恒星演化到红巨星阶段时,由于向内非常延伸的对流包层的存在,锂的丰度A(Li)=12+ lg[n(Li)/n(H)]应为A(Li)<0.5.但是,陆续有处于不同光谱型、不同演化阶段的富锂巨星被发现,其中一些巨星的锂丰度甚至远超出宇宙大爆炸的原初锂丰度,给经典恒星演化模型带来了难题.回顾了从恒星主序到巨星支的锂丰度观测研究历史,并详细介绍了我们对银河系矮星系中富锂巨星的最新发现,总结了所有富锂巨星的观测证据,以及为解决此难题所提出的理论解释.%Lithium is efficiently destroyed via the 7Li(p, a)4He reaction when the temperature reaches T > 2.5 ≈106 K . The standard model of stellar evolution predicts that the Li abundances of evolved red giants, whose convective envelopes reach such high temperatures, should be below A(Li)=0.5. However, some giants with various spectral types and at various evolutionary stages have been found to have higher Li abundances. Some of them have Li abundances even higher than the primordial abundance from the Big Bang. Such discoveries challenge the standard theory of stellar evolution. We review Li abundance observations from the main sequence to the red giant branch. The latest survey for Li-rich giants in the dwarf galaxies of the Milky Way is discussed in detail, including the most metal-poor Li-rich giants known to date. Because lots of the stars have a Li abundance larger than the universe's primordial value, lithium in these stars must have been created rather than survived from destruction. This article provides an overview on the current status of the observations of Li-rich giants and the possible scenarios proposed so far to explain their lithium enhancement.

  1. Giant Panda habitat selection in the Foping Nature Reserve, China

    NARCIS (Netherlands)

    Liu, X.; Toxopeus, A.G.; Skidmore, A.K.; Shao, X.; Dang, D.; Wang, T.; Prins, H.H.T.

    2005-01-01

    Little is known about habitat selection of the giant panda (Ailuropoda melanoleuca), especially about the relationship between giant panda presence and bamboo and tree structures. We presented data on giant panda habitat use and selection in Foping Nature Reserve (NR), China. We used 1,066

  2. Observing giant panda habitat and forage abundance from space

    NARCIS (Netherlands)

    Wang, T.

    2009-01-01

    Giant pandas are obligate bamboo grazers. The bamboos favoured by giant pandas are typical forest understorey plants. Therefore, the availability and abundance of understorey bamboo is a key factor in determining the quantity and quality of giant panda food resources. However, there is little or

  3. Giant Panda habitat selection in the Foping Nature Reserve, China

    NARCIS (Netherlands)

    Liu, X.; Toxopeus, A.G.; Skidmore, A.K.; Shao, X.; Dang, D.; Wang, T.; Prins, H.H.T.

    2005-01-01

    Little is known about habitat selection of the giant panda (Ailuropoda melanoleuca), especially about the relationship between giant panda presence and bamboo and tree structures. We presented data on giant panda habitat use and selection in Foping Nature Reserve (NR), China. We used 1,066 radiotrac

  4. The Mass-Metallicity Relation for Giant Planets

    CERN Document Server

    Thorngren, Daniel P; Lopez, Eric D

    2015-01-01

    Exoplanet discoveries of recent years have provided a great deal of new data for studying the bulk compositions of giant planets. Here we identify 38 transiting giant planets ($20 M_\\oplus 50 M_\\oplus$) suggest significant amounts of heavy elements in H/He envelopes, rather than cores, such that metal-enriched giant planet atmospheres should be the rule.

  5. Normalized spectra of 82 Kepler red giants (Thygesen+, 2012)

    NARCIS (Netherlands)

    A.O. Thygesen; S. Frandsen; H. Bruntt; T. Kallinger; M.F. Andersen; Y.E. Elsworth; S. Hekker; C. Karoff; D. Stello; K. Brogaard; C. Bruke; D.A. Caldwell; J.L. Christiansen

    2012-01-01

    Normalized spectra of 82 red giants in the Kepler Field. Target names are as found in the Kepler Input Catalogue (Kepler Mission Team 2009) Also included spectra of 10 well-studied bright giants observed for reference. 9 of the reference giants were chosen from the PASTEL catalogue (Soubiran et al.,

  6. Normalized spectra of 82 Kepler red giants (Thygesen+, 2012) [Dataset

    NARCIS (Netherlands)

    Thygesen, A.O.; Frandsen, S.; Bruntt, H.; Kallinger, T.; Andersen, M.F.; Elsworth, Y.E.; Hekker, S.; Karoff, C.; Stello, D.; Brogaard, K.; Bruke, C.; Caldwell, D.A.; Christiansen, J.L.

    2012-01-01

    Normalized spectra of 82 red giants in the Kepler Field. Target names are as found in the Kepler Input Catalogue (Kepler Mission Team 2009) Also included spectra of 10 well-studied bright giants observed for reference. 9 of the reference giants were chosen from the PASTEL catalogue (Soubiran et al.,

  7. Airway branching morphogenesis in three dimensional culture

    Directory of Open Access Journals (Sweden)

    Gudjonsson Thorarinn

    2010-11-01

    Full Text Available Abstract Background Lungs develop from the fetal digestive tract where epithelium invades the vascular rich stroma in a process called branching morphogenesis. In organogenesis, endothelial cells have been shown to be important for morphogenesis and the maintenance of organ structure. The aim of this study was to recapitulate human lung morphogenesis in vitro by establishing a three dimensional (3D co-culture model where lung epithelial cells were cultured in endothelial-rich stroma. Methods We used a human bronchial epithelial cell line (VA10 recently developed in our laboratory. This cell line cell line maintains a predominant basal cell phenotype, expressing p63 and other basal markers such as cytokeratin-5 and -14. Here, we cultured VA10 with human umbilical vein endothelial cells (HUVECs, to mimic the close interaction between these cell types during lung development. Morphogenesis and differentiation was monitored by phase contrast microscopy, immunostainings and confocal imaging. Results We found that in co-culture with endothelial cells, the VA10 cells generated bronchioalveolar like structures, suggesting that lung epithelial branching is facilitated by the presence of endothelial cells. The VA10 derived epithelial structures display various complex patterns of branching and show partial alveolar type-II differentiation with pro-Surfactant-C expression. The epithelial origin of the branching VA10 colonies was confirmed by immunostaining. These bronchioalveolar-like structures were polarized with respect to integrin expression at the cell-matrix interface. The endothelial-induced branching was mediated by soluble factors. Furthermore, fibroblast growth factor receptor-2 (FGFR-2 and sprouty-2 were expressed at the growing tips of the branching structures and the branching was inhibited by the FGFR-small molecule inhibitor SU5402. Discussion In this study we show that a human lung epithelial cell line can be induced by endothelial cells to

  8. Branching structure of uniform recursive trees

    Institute of Scientific and Technical Information of China (English)

    FENG; Qunqiang; SU; Chun; HU; Zhishui

    2005-01-01

    The branching structure of uniform recursive trees is investigated in this paper.Using the method of sums for a sequence of independent random variables, the distribution law of ηn, the number of branches of the uniform recursive tree of size n are given first. It is shown that the strong law of large numbers, the central limit theorem and the law of iterated logarithm for ηn follow easily from this method. Next it is shown that ηn and ξn, the depth of vertex n, have the same distribution, and the distribution law of ζn,m, the number of branches of size m, is also given, whose asymptotic distribution is the Poisson distribution with parameter λ = 1/m. In addition, the joint distribution and the asymptotic joint distribution of the numbers of various branches are given. Finally, it is proved that the size of the biggest branch tends to infinity almost sure as n -→∞.

  9. Highly branched dextrin prepared from high-amylose maize starch using waxy rice branching enzyme (WRBE).

    Science.gov (United States)

    Tian, Yaoqi; Chen, Huangli; Zhang, Xiwen; Zhan, Jinling; Jin, Zhengyu; Wang, Jinpeng

    2016-07-15

    Branching enzyme (BE, EC 2.4.1.18) was isolated from the developing waxy rice endosperm and used to prepare a highly branched dextrin based on high-amylose maize starch (HAMS) as a substrate. The molecular mass of the starch initially degraded quickly from 2.5 × 10(7) to 4.1 × 10(5)Da, and then stabilized, with a minimal increase during the BE treatment. The resultant branched dextrin had a narrow size distribution, with a mean molecular weight of 5.1 × 10(5)Da and a polydispersity index (PI) of 1.567. The results of high-performance anion exchange chromatography indicated that the degree of polymerization (DP) of the branched chains ranged from 3 to 27; approximately 75.26% of these chains were short (DPhighly branched dextrins with a narrow size distribution and short side chains. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. 46 CFR 169.690 - Lighting branch circuits.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Lighting branch circuits. 169.690 Section 169.690... branch circuits. Each lighting branch circuit must meet the requirements of § 111.75-5 of this chapter... to a lighting distribution panelboard; and (b) Branch circuits in excess of 30 amperes may...

  11. The branching channel network in the Yangtze Estuary

    NARCIS (Netherlands)

    Wang, Z.B.; Ding, P.X.

    2012-01-01

    The channels in the Yangtze Estuary have an ordered-branching structure: The estuary is first divided by the Chongming Island into the North Branch and the South Branch. Then the South Branch is divided into the North Channel and South Channel by the Islands Changxing and Hengsha. The South Channel

  12. Abundance differences among G and K giants

    Science.gov (United States)

    Challener, Sharon Lynn Montgomery

    Effective temperatures and surface gravities were derived for 52 G and K giants using model atmosphere. Of these, 33 were called very strong-lined (or VSL) stars primarily because of their CN line strength. We find that when compared to normal stars, the VSL stars show a mean iron overabundance of 0.15 dex. Contrary to earlier suggestions, none of the heavier elements (Z greater than 10) appear selectively enhanced. Red giants are believed to undergo mixing, thereby driving the surface abundances towards those of the stellar interior. Carbon, nitrogen, and oxygen abundances are most sensitive to mixing as they are produced through nucleosynthesis at various depths beneath the star's surface. The CNO abundances (normalized to the iron abundances) of the VSLs appear on average to be normal for G and K giants. This result suggests that the strong CN absorption seen in VSLs is not the result of unusual mixing. Their general overabundance of metal appears instead to be innate, presumably reflecting the metallicity of the gaseous clouds from which they formed. This should be settled once the appropriate number of VSL dwarfs is found. The deviations from the normal population of giants are rather small, however, and certainly not of the magnitude envisioned by Spinrad and Taylor (1969). It is likely that VSLs are merely the stars lying in the tail of the normal abundance distribution.

  13. Giant Viruses of Amoebas: An Update.

    Science.gov (United States)

    Aherfi, Sarah; Colson, Philippe; La Scola, Bernard; Raoult, Didier

    2016-01-01

    During the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea, and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreover, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages.

  14. Standing on the shoulders of giants.

    Science.gov (United States)

    Romanovsky, Andrej A

    2014-01-01

    In this editorial, the author explains that the journal Temperature stands on the shoulders of giants-prominent scientists of the past and current members of the Temperature community. Temperature also uses the best tools, such as Google Scholar profiles. The editorial includes a new puzzle: why does warm water freeze faster than cold water?

  15. Giant Magnetostrictive Material Exciter for Panel Loudspeaker

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; ZHANG Yong-fa

    2008-01-01

    The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system.The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distributed mode panel is introduced and how exciter parameters influence panel lffudspeaker's performance is discussed.NumericaI predictions are given in order to show how these influences are manifested.

  16. Giant melanoma of the left thumb

    NARCIS (Netherlands)

    Zeebregts, CJAM; Schraffordt Koops, H.

    2000-01-01

    A 74-year-old female patient is described with a giant melanoma of the left thenar and concomitant bilateral pulmonary metastases. Palliative treatment consisted of a two-staged procedure in order to save the limb from amputation. Firstly, perfusion with gamma-interferon, tumour necrosis factor-alph

  17. Southern Africa - a giant natural photochemical reactor

    CSIR Research Space (South Africa)

    Diab, RD

    2006-04-01

    Full Text Available The analogy of a ‘giant natural photochemical reactor’ is extended in this paper to the central and southern African tropics, where tropospheric ozone enhancement occurs over a vast geographical area from the Congo to South Africa, and over a long...

  18. Tuberculosis Detection by Giant African Pouched Rats

    Science.gov (United States)

    Poling, Alan; Weetjens, Bart; Cox, Christophe; Beyene, Negussie; Durgin, Amy; Mahoney, Amanda

    2011-01-01

    In recent years, operant discrimination training procedures have been used to teach giant African pouched rats to detect tuberculosis (TB) in human sputum samples. This article summarizes how the rats are trained and used operationally, as well as their performance in studies published to date. Available data suggest that pouched rats, which can…

  19. Giant viruses of amoebas: an update

    Directory of Open Access Journals (Sweden)

    Sarah eAherfi

    2016-03-01

    Full Text Available During the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreoever, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages.

  20. Insights on a Giant Aneurysm Treated Endovascularly.

    Science.gov (United States)

    Graziano, Francesca; Iacopino, Domenico Gerardo; Ulm, Arthur John

    2016-07-01

    Background Endovascular treatment with stent-assisted Guglielmi detachable coils is an accepted method for treating intracranial giant aneurysms that otherwise would require more invasive or destructive treatment or could not be treated at all. Nevertheless, there is a paucity of information concerning inner postcoiling aneurysmal changes in human subjects over the long term. We report a postmortem analysis of a patient with a giant aneurysm at the vertebrobasilar junction (VBJ) who was treated endovascularly and studied pathologically 24 months after treatment. Materials and Method The head was removed at autopsy and prefixed in a 10% neutral buffered formalin solution. The brain was gently removed from the skull base after cutting the intracranial nerves and vascular structures. The giant VBJ aneurysm and its relationship with the brainstem, cranial nerves, and vessels were captured photographically and analyzed. Afterward, under operating microscope guidance, the vertebrobasilar system with the aneurysm was gently and carefully detached from the brainstem and carefully analyzed. Results No complete fibrous obliteration of the aneurysm lumen could be detected in our case, and no endothelialization had taken place 24 months after treatment. Conclusions Our findings agree with those of previous similar reports. Coiling, in particular in large or giant aneurysms, may be burdened by the risk of coil compaction and recanalization, but it has the advantage of not affecting the flow in the perforating arteries.