English
Related papers

Related papers: Alkali Line Profiles in Degenerate Dwarfs

200 papers

The cold dark matter scenario predicts that a large number of dark subhalos should be located within the halo of each Milky-way sized galaxy. One tell-tale signature of such dark subhalos could be additional milliarcsecond-scale image…

Astrophysics · Physics 2009-11-13 E. Zackrisson , T. Riehm , O. Moeller , K. Wiik , P. Nurmi

We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our…

Earth and Planetary Astrophysics · Physics 2017-02-22 Jack S. Yates , Paul I. Palmer , Beth Biller , Charles S. Cockell

We present new cloudy and cloudless model atmospheres for brown dwarfs using recent ab initio calculations of the line list of ammonia (NH3) and of the collision-induced absorption of molecular hydrogen (H2). We compare the new synthetic…

Solar and Stellar Astrophysics · Physics 2015-06-04 D. Saumon , M. S. Marley , M. Abel , L. Frommhold , R. S. Freedman

We present a detailed comparison of the ionizing spectral energy distributions (SEDs) predicted by four modern stellar atmosphere codes, TLUSTY, CMFGEN, WMbasic, and FASTWIND. We consider three sets of stellar parameters representing a late…

Astrophysics · Physics 2009-11-13 S. Simón-Díaz , G. Stasińska

Dust properties are very likely affected by the environment in which dust grains evolve. For instance, some analyses of cold clumps (7 K- 17 K) indicate that the aggregation process is favored in dense environments. However, studying warm…

Ultracool subdwarfs are low luminosity, late-type M and L dwarfs that exhibit spectroscopic indications of subsolar metallicity and halo kinematics. Their recent discovery and ongoing investigation have led to new insights into the role of…

A search for emission lines in foreground galaxies in quasar spectra (z(gal) < z(QSO)) of the Sloan Digital Sky Survey (SDSS) data release 5 (DR5) reveals 23 examples of quasars shining through low redshift, foreground galaxies at small…

Taking advantage of the Gaia Data Release 2, recent studies have revisited the evolution of carbon-polluted white dwarfs (DQs) across a large range of effective temperatures. These analyses have clearly confirmed the existence of two…

Solar and Stellar Astrophysics · Physics 2019-11-06 S. Blouin , P. Dufour

We present new cooling models for carbon-oxygen white dwarfs with both H- and He-atmospheres, covering the whole relevant mass range, to extend our updated BaSTI (a Bag of Stellar Tracks and Isochrones) stellar evolution archive. They have…

Solar and Stellar Astrophysics · Physics 2021-12-22 Maurizio Salaris , Santi Cassisi , Adriano Pietrinferni , Sebastian Hidalgo

We present a theoretical study of the effects and signatures of realistic velocity field and atmospheric inhomogeneities associated with convective motions at the surface of cool late-type stars on the emergent profiles of iron spectral…

Solar and Stellar Astrophysics · Physics 2014-03-26 Zazralt Magic , Remo Collet , Martin Asplund

We present a detailed spectroscopic analysis of 115 helium-line (DB) and 28 cool, He-rich hydrogen-line (DA) white dwarfs based on atmosphere fits to optical spectroscopy and photometry. We find that 63% of our DB population show hydrogen…

Solar and Stellar Astrophysics · Physics 2018-05-02 Benoit Rolland , Pierre Bergeron , Gilles Fontaine

We have investigated molecular distributions in protoplanetary disks, adopting a disk model with a temperature gradient in the vertical direction. The model produces sufficiently high abundances of gaseous CO and HCO+ to account for line…

Astrophysics · Physics 2009-11-07 Y. Aikawa , G. J. van Zadelhoff , E. F. van Dishoeck , E. Herbst

We present a reanalysis of the HeII Lyman alpha absorption towards the quasars HS1700+6416 and HE2347-4342 using new high S/N, optical observations. An alternative analysis method is applied, which fits the high quality, optical HI data…

Astrophysics · Physics 2009-11-11 C. Fechner , D. Reimers

We present high S/N measurements of the H I Ly alpha absorption line toward 16 Galactic targets which are at distances between approximately 190 and 2200 pc, all beyond the wall of the Local Bubble. We describe the models used to remove…

Astrophysics of Galaxies · Physics 2023-04-05 S. D. Friedman , P. Chayer , E. B. Jenkins , T. M. Tripp , G. M. Williger , G. Hebrard , P. Sonnentrucker

We present $Spitzer$ IRS 5--14 $\mu$m spectra and 16 $\mu$m and 22 $\mu$m photometry of the T2.5 companion to the $\sim$300 Myr-old G0V star HN Peg. We incorporate previous 0.8--5 $\mu$m observations to obtain the most comprehensive…

Solar and Stellar Astrophysics · Physics 2021-10-27 Genaro Suárez , Stanimir Metchev , Sandy K. Leggett , Didier Saumon , Mark S. Marley

Temperature, surface gravity, and metallicitity are basic stellar atmospheric parameters necessary to characterize a star. We aim to improve the description of the spectroscopic temperatures especially for the cooler stars where the…

Solar and Stellar Astrophysics · Physics 2015-06-15 M. Tsantaki , S. G. Sousa , V. Zh. Adibekyan , N. C. Santos , A. Mortier , G. Israelian

The spectral energy distribution (SED) of recent star formation regions is dominated by the more massive and early stars (O and B types). These stars show large and very significant absorption features, the most prominent being the…

Astrophysics · Physics 2007-05-23 Mercedes Molla , Angeles I. Diaz , Mar Alvarez Alvarez , Rosa Gonzalez Delgado

Besides the need of Stark broadening parameters for a number of problems in physics, and plasma technology, in hot star atmospheres the conditions exist where Stark widths are comparable and even larger than the thermal Doppler widths.…

Solar and Stellar Astrophysics · Physics 2018-03-14 Z. Simic , M. S. Dimitrijevic , A. B. Kovacevic , S. Sahal-Brechot

We present work on H alpha spectral line characteristics in PHOENIX stellar model atmospheres and their comparison to microlensing observations. We examine in detail the H alpha equivalent width (EW) and the line shape characteristics for…

Astrophysics · Physics 2009-11-11 Christine Thurl , Penny D. Sackett , Peter H. Hauschildt

We present optical (6500-9200A) spectroscopy of eight cool dwarfs detected in a 231 square degree ``Mini-survey'' of the Deep NEar Infrared Survey (DENIS) data. We are able to confirm that the spectral types derived from the Mini-survey…

Astrophysics · Physics 2007-05-23 C. G. Tinney , X. Delfosse , T. Forveille , F. Allard