Zobrazeno 1 - 10
of 578
pro vyhledávání: '"Lambert, David L"'
Autor:
Pozhath, Ramya, Lambert, David L.
A sample of warm low level semi-regular variables chosen from the General Catalogue of Variable Stars is studied for their chemical compositions by analysing high resolution optical spectra. The abundance ratios from Na/Fe to Eu/Fe displayed by these
Externí odkaz:
http://arxiv.org/abs/2406.10526
We present the results of a sensitive search for high-velocity gas in interstellar absorption lines associated with the Cygnus Loop supernova remnant (SNR). We examine high-resolution, high signal-to-noise ratio optical spectra of six stars in the Cy
Externí odkaz:
http://arxiv.org/abs/2401.00960
Autor:
Ritchey, Adam M., Jenkins, Edward B., Shull, J. Michael, Savage, Blair D., Federman, S. R., Lambert, David L.
Publikováno v:
ApJ, 952:57 (26pp), 2023
In this investigation, we present an analysis of the metallicity distribution that pertains to neutral gas in the local Galactic interstellar medium (ISM). We derive relative ISM metallicities for a sample of 84 sight lines probing diffuse atomic and
Externí odkaz:
http://arxiv.org/abs/2301.09743
Autor:
Deepak, Lambert, David L.
Lithium abundances for red giants in the GALAH DR3 survey are studied. The rare examples of Li-enriched stars with abundances A(Li) $\geq 1.5$ are confirmed to be He-core burning stars belonging to or evolved from the red clump with similar masses an
Externí odkaz:
http://arxiv.org/abs/2107.04624
Autor:
Federman, S. R., Rice, Johnathan S., Ritchey, A. M., Kim, Hwihyun, Lacy, John H., Goldsmith, Paul F., Flagey, Nicolas, Mace, Gregory N., Lambert, David L.
Publikováno v:
ApJ, 914, 59 (2021)
We study four lines of sight that probe the transition from diffuse molecular gas to molecular cloud material in Taurus. Measurements of atomic and molecular absorption are used to infer the distribution of species and the physical conditions toward
Externí odkaz:
http://arxiv.org/abs/2106.12748
Autor:
Deepak, Lambert, David L.
In this study, we explore the evolution of lithium in giant stars based on data assembled from the literature on asteroseismology and Li abundances for giants. Our final sample of 187 giants consists of 44 red giant branch (RGB), 140 core He-burning
Externí odkaz:
http://arxiv.org/abs/2104.11741
Autor:
Rao, N. Kameswara, Lambert, David L., Reddy, Arumalla B. S., García-Hernández, D. A., Manchado, Arturo, Díaz-Luis, J. J.
We have detected CH$^{+}$ and CH molecular absorption lines from the young compact planetary nebula IC 4997 from high resolution optical spectra. A high-resolution infra-red (H and K bands) spectrum provides detection of H$_2$ emission lines amongst
Externí odkaz:
http://arxiv.org/abs/2005.00903
Compositions of lithium-enriched and normal giants among the GALAH survey are compared. Except for Li, the only detectable abundance difference between lithium-enriched and normal giants among the investigated elements from carbon to europium occurs
Externí odkaz:
http://arxiv.org/abs/2003.05381
The hydrogen-deficient star DY Cen has been reported as an R CrB-type variable, an extreme helium star (with some hydrogen), and as a single-lined spectroscopic binary. It has been associated with a dramatic change in visual brightness and colour cor
Externí odkaz:
http://arxiv.org/abs/2002.03931
The main objective of this paper is to explore abundances of fluorine in hot Extreme Helium Stars (EHes). Overabundance of fluorine is a characteristic feature for cool EHes and R Coronae Borealis (RCB) stars and further enforces their close connecti
Externí odkaz:
http://arxiv.org/abs/2001.07472