Search Publications
Bayesian Ages for Early-type Stars from Isochrones Including Rotation, and a Possible Old Age for the Hyades
Huang, Chelsea X.; Brandt, Timothy D.
We combine recently computed models of stellar evolution using a new treatment of rotation with a Bayesian statistical framework to constrain the ages and other properties of early-type stars. We find good agreement for early-type stars and clusters with known young ages, including β Pictoris, the Pleiades, and the Ursa Majoris moving group. Howev…
Systematic Non-LTE Study of the -2.6 < [Fe/H] < 0.2 F and G dwarfs in the Solar Neighborhood. I. Stellar Atmosphere Parameters
Zhang, H. -W.; Chen, Y.; Shi, J. -R. +9 more
We present atmospheric parameters for 51 nearby F and G dwarf and subgiant stars uniformly distributed over the -2.60< [{Fe}/{{H}}]< +0.20 metallicity range that is suitable for the Galactic chemical evolution research. Lines of iron in the two ionization stages, Fe I and Fe II, were used to derive a homogeneous set of effective temperatures…
A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic Analysis
Corcoran, M. F.; Hamann, W. -R.; Nazé, Y. +13 more
Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system. The primary’s distance-in…
Revealing δ Cephei's Secret Companion and Intriguing Past
Holl, B.; Mowlavi, N.; Roelens, M. +5 more
Classical Cepheid variable stars are crucial calibrators of the cosmic distance scale thanks to a relation between their pulsation periods and luminosities. Their archetype, δ Cephei, is an important calibrator for this relation. In this paper, we show that δ Cephei is a spectroscopic binary based on newly obtained high-precision radial velocities…
Dynamics of Rotation in M Dwarfs: Indications for a Change in the Dynamo Regime in Stars at the Onset of Complete Convection
Mullan, D. J.; Houdebine, E. R.
We have measured vsin i with high precision for a sample of dM3 stars (86 targets). We detected rotation in 82 stars (73 dM3 stars and nine dM3e stars). We compare our measurements of vsin i for all of the stars in our dM0, dM2, dM3, and dM4 samples to those from other authors. We find a good agreement down to vsin i values of less than 1 km s
Multiplicity among F-type stars. II.
Chini, R.; Fuhrmann, K.
In continuation of our previous study we present an updated census of new companions and model atmosphere analyses for some 50 southern dwarfs, mostly in the mass range 0.90≤slant M≤slant 1.10 {M}⊙ . For the common-proper-motion companions µ Vir B, HR 2225 B, HD 67199 B, and HD 114853 B, we confirm their physical association from …
Updated 24 µm Period-Luminosity Relation Derived from Galactic Cepheids
Ngeow, Chow-Choong; Kanbur, Shashi M.; Bhardwaj, Anupam +2 more
In this work, we updated the catalog of Galactic Cepheids with 24 µm photometry by cross-matching the positions of known Galactic Cepheids to the recently released MIPSGAL point source catalog. We have added 36 new sources featuring MIPSGAL photometry in our analysis, thus increasing the existing sample to 65. Six different sources of compil…
Infrared Spectral Properties of M Giants
Sloan, G. C.; Goes, C.; Ramirez, R. M. +2 more
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 µm which we identify as water vapor, and in some cases, the absorption extends from 6.4 µm into the SiO band at 7.5 µm. Variable stars show stronger H2O absorption. While the stre…