Results 31 to 40 of about 373,456 (271)

Kinematic study of planetary nebulae in NGC 6822 [PDF]

, 2014
By measuring precise radial velocities of planetary nebulae (which belong to the intermediate age population), H II regions, and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine if both types of ...
Flores-Durán, S. N., García-Rojas, J., Hernández-Martínez, L., Peña, M., Ruiz, M. T.   +4 more
core   +1 more source

A Survey for C ii Emission-line Stars in the Large Magellanic Cloud. II. Final Results and the Origin of C ii Emission in [WC] Spectra

The Astrophysical Journal, 2023
We present the final results of an imaging and spectroscopic search for stars in the Large Magellanic Cloud (LMC) with C ii λλ 7231, 7236 emission lines. The goal is to identify and study [WC11] stars, the coolest of the low-mass Wolf–Rayet sequence, and
Bruce Margon, Nidia Morrell, Philip Massey, Kathryn F. Neugent, Robert Williams   +4 more
doaj   +1 more source

Cosmic Chemical Evolution with an Early Population of Intermediate Mass Stars [PDF]

, 2010
We explore the consequences of an early population of intermediate mass stars in the 2 - 8 M\odot range on cosmic chemical evolution. We discuss the implications of this population as it pertains to several cosmological and astrophysical observables. For
Fields, Brian D., Olive, Keith A., Silk, Joseph, Vangioni, Elisabeth   +3 more
core   +2 more sources

Chemical constraints on the contribution of Population III stars to cosmic reionization

, 2013
Recent studies have highlighted that galaxies at z = 6-8 fall short of producing enough ionizing photons to reionize the IGM, and suggest that Population III stars could resolve this tension, because their harder spectra can produce ~10x more ionizing ...
Hennawi, Joseph F., Kulkarni, Girish, Rollinde, Emmanuel, Vangioni, Elisabeth   +3 more
core   +2 more sources

HST Snaphot Study of Variable Stars in Globular Clusters: Inner Region of NGC 6441

, 2003
[Abridged] We present the results of a Hubble Space Telescope snapshot program to survey the inner region of the globular cluster NGC 6441 for its variable stars.
Allen V. Sweigart, Andrew C. Layden, Barton J. Pritzl, Bono G., Borissova J., Castellani V., Clement C. M., Demers S., Dickens R. J., Gingold R. A., Horace A. Smith, Kaluzny J., Kinman T. D., Kwee K. K., Lee S. W., Longmore A. J., Moehler S., Mrcio Catelan, Oosterhoff P. Th., Peter B. Stetson, Pike C. D., Pinto G., R. Michael Rich, Renzini A., Russeva T., Russeva T., Russeva T., Sweigart A. V., Wehlau A., Wehlau A.   +29 more
core   +1 more source

Tracing ωCentauri’s origins: Spatial and chemical signatures of its formation history

Astronomy & Astrophysics
ωCentauri (ωCen), with its unmatched chemical complexity, is the most enigmatic Galactic globular cluster (GC). We combine photometric and spectroscopic catalogs to identify distinct stellar populations within ωCen, investigate their spatial distribution
Dondoglio E., Milone A. P., Marino A. F., Mastrobuono-Battisti A., Bortolan E., Legnardi M. V., Ziliotto T., Muratore F., Cordoni G., Lagioia E. P., Tailo M.   +10 more
doaj   +1 more source

[Fe/H]Ratios in Population II Stars [PDF]

Symposium - International Astronomical Union, 1991
Abundances of Population II stars of the field and globular cluster systems are reviewed. Emphasis is placed on [Fe/H] ratios determined from analyses of moderate- and high-resolution spectroscopic data. The status of analyses of metal-deficient stars is examined from the viewpoint of number of analyses and number of stars, overall distribution of the [
openaire   +1 more source

Populations of rotating stars [PDF]

Astronomy & Astrophysics, 2013
Accepted for publication in A&A, language ...
Granada, A.; Ekström, S.; Georgy, C.; Krtička, J.; Owocki, S.; Meynet, G.; Maeder, A.   +7 more
openaire   +2 more sources

The Contribution of the First Stars to the Cosmic Infrared Background [PDF]

, 2001
We calculate the contribution to the cosmic infrared background from very massive metal-free stars at high redshift. We explore two plausible star-formation models and two limiting cases for the reprocessing of the ionizing stellar emission. We find that
Callaway, Callaway, M. Kamionkowski, M. R. Santos, V. Bromm   +4 more
core   +5 more sources

Classification of Metal-Deficient Dwarfs in the Vilnius Photometric System

Open Astronomy, 2003
Methods used for the quantitative classification of metal-deficient stars in the Vilnius photometric system are reviewed. We present a new calibration of absolute magnitudes for dwarfs and subdwarfs, based on Hipparcos parallaxes.
Lazauskaitė R., Bartkevičius A., Bartašiūtė S.   +2 more
doaj   +1 more source