Results 1 to 10 of about 992,258 (306)

First Stellar Abundances in NGC 6822 from VLT-UVES and Keck-HIRES Spectroscopy [PDF]

, 2000
We have obtained the first high-resolution spectra of individual stars in the dwarf irregular galaxy NGC 6822. The spectra of the two A-type supergiants were obtained at the Very Large Telescope and Keck Observatories, using the Ultraviolet-Visual ...
K. Venn, D. Lennon, A. Kaufer, J. K. McCarthy, N. Przybilla, R. Kudritzki, M. Lemke, E. Skillman, S. Smartt   +8 more
semanticscholar   +1 more source

Evolved Stars with Inconsistent Age Estimates: Abundance Outliers or Mass Transfer Products?

The Astrophysical Journal
In the Milky Way disk, there is a strong trend linking stellar age to surface element abundances. Here, we explore this relationship with a data set of 8803 red-giant and red-clump stars with both asteroseismic data from NASA Kepler Mission and surface ...
Polly Frazer, Emily J. Griffith, David W. Hogg, Amaya Sinha, Jamie Tayar   +4 more
doaj   +1 more source

First Stellar Abundances in the Dwarf Irregular Galaxy Sextans A [PDF]

, 2004
We present the abundance analyses of three isolated A-type supergiant stars in the dwarf irregular galaxy Sextans A (=DDO 75) from high-resolution spectra obtained with the Ultraviolet-Visual Echelle Spectrograph (UVES) on the Kueyen telescope (UT2) of ...
A. Kaufer, K. Venn, E. Tolstoy, C. Pinte, R. Kudritzki   +4 more
semanticscholar   +1 more source

A Systematic NLTE Study of Very Metal-poor Stars with Metallicity down to −4.3 dex. VI. Light Neutron-capture Elements and the Sr–Na Correlation as a Signature of Spinstar Nucleosynthesis in the Early Galaxy

The Astrophysical Journal
We present a non–local thermodynamic equilibrium (NLTE) abundance analysis of the light neutron-capture elements Sr, Y, and Zr in a sample of 103 very metal-poor stars spanning −4.3 ≲ [Fe/H] ≲ −1.7, based on high-resolution Subaru/HDS spectra and ...
Sofya Alexeeva, Hongliang Yan, Gang Zhao, Jianrong Shi, Haining Li, Shuai Liu, Zeming Zhou, Junbo Zhang, Jingkun Zhao, Yaqian Wu, Yuqin Chen, Huiling Chen, Huawei Zhang, Wako Aoki   +13 more
doaj   +1 more source

About trend in zinc stellar abundances with metallisity

Odessa Astronomical Publications, 2007
We have carried out investigation of zinc abundance behavior in wide range of stellar metallicities from 0 to -5. It has been determined zinc abundance using our Zn atom model and NonLTE calculation method.
U. Sh. Bayazitov, F. Thevenin
doaj   +1 more source

What Physical Factors Influence the Transformation between Blue Supergiants and Red Supergiants?

The Astrophysical Journal
The post-main-sequence evolution of massive stars is highly sensitive to key stellar model parameters, particularly initial rotational velocity and metallicity.
Yun He, Hanfeng Song, Georges Meynet, Andre Maeder, Ruiyu Zhang, Ying Qin, Shitao Qi, Qingli Li, Qiong Zhan   +8 more
doaj   +1 more source

The Metal-Rich Universe: Formation and evolution of the Galactic bulge: constraints from stellar abundances [PDF]

, 2006
Aims. We compute the chemical evolution of the Galactic bulge in the context of an inside-out model for the formation of the Milky Way. The model contains updated stellar yields from massive stars.
S. Ballero, F. Matteucci, L. Origlia, R. M. Rich   +3 more
semanticscholar   +1 more source

Anchoring Stellar Age Indicators: A Cross Calibration of [C/N] and Gyrochronology Ages via the Age–Velocity Dispersion Relation

The Astronomical Journal
Determining stellar ages is challenging, as it depends on other stellar parameters in a nonlinear way and often relies on stellar evolution models to infer the underlying relation between these parameters and age. This complexity increases when comparing
Yuxi(Lucy) Lu, Marc H. Pinsonneault, Yuan-Sen Ting, Phil R. Van-Lane, John D. Roberts, Jamie Tayar, Alexander Stone-Martinez, Amanda L. Ash   +7 more
doaj   +1 more source

Gaia FGK benchmark stars

Astronomy & Astrophysics
Context. In the current era, in which an unprecedented wealth of data are available for the study of the Milky Way, Gaia benchmark stars (GBSs) have become an established reference and calibration sample. Studies of stellar structure and evolution and of
Vitali S., Jofré P., Casamiquela L., Soubiran C., Heiter U., Aguilera-Gómez C., Barrios-López D., Blanco-Cuaresma S., Escorza A., Hernández-Araya I., Signor T., Sinclair-Wentworth H., Worley C.   +12 more
doaj   +1 more source

The Impact of Initial Composition on Massive Star Evolution and Nucleosynthesis

The Astrophysical Journal
We study the sensitivity of presupernova evolution and supernova nucleosynthesis yields of massive stars to variations of the initial composition. We use the solar abundances from Lodders, and compute two different sets of initial stellar compositions ...
Christopher West, Alexander Heger, Benoit Côté, Lev Serxner, Haoxuan Sun   +4 more
doaj   +1 more source