Results 1 to 10 of about 63,603 (275)

Stellar and gaseous abundances in M82

The Astrophysical Journal, 2004
The near infrared (IR) absorption spectra of starburst galaxies show several atomic and molecular lines from red supergiants which can be used to infer reliable stellar abundances. The metals locked in stars give a picture of the galaxy metallicity prior
A. Comastri, Alloin D., Cappi M., Coziol R., Grevesse N., L. Origlia, McCall M. L., Oliva E., Oliva E., Origlia L., Origlia L., P. Ranalli, Pagel B. E. J., R. Maiolino, Stasinska G.   +14 more
core   +2 more sources

The far-ultraviolet spectra of two hot PG1159 stars

, 2016
PG1159 stars are hot, hydrogen-deficient (pre-) white dwarfs with atmospheres mainly composed of helium, carbon, and oxygen. The unusual surface chemistry is the result of a late helium-shell flash.
Kruk, J. W., Rauch, T., Werner, K.
core   +1 more source

A near field cosmology study of heavy elements in very metal-poor stars

, 2012
Studying a range of old metal-poor stars provides information over cosmological timescales of our Galaxy. Such studies are indicative of the pristine gases and evolution of the Milky Way.
Hansen, Camilla. J.
core   +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

Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra

, 2006
We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of another ...
Arnaud M., Barnes T. G., Brian E. Wood, Grevesse N., Jeffrey L. Linsky, Kashyap V., Perryman M. A. C., Shemi A., Veck N. J., von Steiger R.   +9 more
core   +2 more sources

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

Selecting a Photometric System for Gaia: C, N, O and Alpha-Process Elements

Open Astronomy, 2003
The sensitivity of stellar spectra to C, N, O and α-process element abundances is discussed with the aim of taking this effect into account when selecting a photometric system for the Gaia orbiting observatory.
Tautvaišienė G., Edvardsson B., Bartašiūtė S.   +2 more
doaj   +1 more source

The halo+cluster system of the Galactic globular cluster NGC1851

, 2014
NGC1851 is surrounded by a stellar component that extends more than ten times beyond the tidal radius. Although the nature of this stellar structure is not known, it has been suggested to be a sparse halo of stars or associated with a stellar stream.
Angeloni, R., Aparicio, A., Asplund, M., Bedin, L. R., Buonanno, R., Cassisi, S., Da Costa, G., Dotter, A., Jerjen, H., Lind, K., Mackey, D., Marino, A. F., Milone, A. P., Monelli, M., Norris, J., Piotto, G., Sbordone, L., Stetson, P. B., Weiss, A., Yong, D.   +19 more
core   +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 Impact of Diffusion and Turbulent Mixing on Chemical Abundance Variations in the Open Cluster NGC 2420

The Astrophysical Journal
The mixing of material in stellar envelopes critically determines surface elemental abundances. A well-established tension remains between theoretical models and observational data for stars near the main-sequence turn-off.
Fei Guo, Xue-Feng Li, Yan Li
doaj   +1 more source