Results 31 to 40 of about 72,602 (336)

Dynamical Substructures of Galactic Globular Clusters III. NGC 7006 [PDF]

Journal of Astronomy and Space Sciences, 2005
To study the effects of giant population on dynamical substructures of the central region of NGC 7006, we examine the radial variations of ellipticity and position angle on BV stellar photometry using ellipse fitting technique.
Jonghwan Rhee, Young-Jong Sohn
doaj   +1 more source

RR Lyrae Stars as Seen by the Kepler Space Telescope

Frontiers in Astronomy and Space Sciences, 2021
The unprecedented photometric precision along with the quasi-continuous sampling provided by the Kepler space telescope revealed new and unpredicted phenomena that reformed and invigorated RR Lyrae star research.
Emese Plachy, Emese Plachy, Emese Plachy, Róbert Szabó, Róbert Szabó, Róbert Szabó   +5 more
doaj   +1 more source

The ages of stars: The horizontal branch [PDF]

Proceedings of the International Astronomical Union, 2008
AbstractHorizontal branch (HB) stars play a particularly important role in the “age debate,” since they are at the very center of the long-standing “second parameter” problem. In this review, I discuss some recent progress in our understanding of the nature and origin of HB stars.
openaire   +2 more sources

On the 3He anomaly in hot subdwarf B stars

Open Astronomy, 2017
Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB) stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere
Schneider David, Irrgang Andreas, Heber Ulrich, Nieva Maria F., Przybilla Norbert   +4 more
doaj   +1 more source

A Spectroscopic Survey of Field Red Horizontal-branch Stars [PDF]

The Astronomical Journal, 2018
Abstract A metallicity, chemical composition, and kinematic survey has been conducted for a sample of 340 candidate field red horizontal-branch (RHB) stars. Spectra with high resolution and high signal-to-noise ratio were gathered with the McDonald Observatory 2.7 m Tull and the Hobby–Eberly Telescope echelle spectrographs, and were used
Melike Afşar, Zeynep Bozkurt, Gamze Böcek Topcu, Dana I. Casetti-Dinescu, Christopher Sneden, Gizem Şehitog̅lu   +5 more
openaire   +4 more sources

Discovery of Blue Hook Stars in the Massive Globular Cluster M54

, 2003
We present BV photometry centered on the globular cluster M54 (NGC 6715). The color-magnitude diagram clearly shows a blue horizontal branch extending anomalously beyond the zero age horizontal branch theoretical models.
Alejandra Recio‐Blanco, Alfred Rosenberg, Bedin L. R., Busso G., Cassisi S., Macarena Garcia‐Marin, Moehler S., Sweigart A. V.   +7 more
core   +1 more source

ε-mechanism driven pulsations in hot subdwarf stars with mixed H-He atmospheres

Open Astronomy, 2017
The ε mechanism is a self-excitation mechanism of stellar pulsations which acts in regions where nuclear burning takes place. It has been shown that the ε mechanism can excite pulsations in hot pre-horizontal branch stars before they settle into the ...
Battich Tiara, Bertolami Marcelo M. Miller, Córsico Alejandro H., Althaus Leandro G.   +3 more
doaj   +1 more source

Hot subdwarf stars in close-up view - II. Rotational properties of single and wide binary subdwarf B stars

, 2012
Subluminous B stars (sdBs) form the extremely hot end of the horizontal branch and are therefore related to the blue horizontal branch (BHB) stars. While the rotational properties of BHB stars have been investigated extensively, studies of sdB stars have
Bear, Behr, Behr, Behr, Behr, Berger, Billères, Billères, Blanchette, Brown, Caloi, Carney, Carney, Charpinet, Charpinet, Charpinet, Charpinet, Charpinet, Copperwheat, de Marchi, Deca, Dorman, D’Cruz, Edelmann, Edelmann, Eisenstein, Fabbian, Fontaine, For, Geier, Geier, Geier, Geier, Geier, Geier, Geier, Gourgouliatos, Green, Green, Green, Grundahl, Han, Han, Han, Han, Heber, Heber, Heber, Heber, Hirsch, Iben, Jeffery, Kawaler, Kilkenny, Kilkenny, Kinman, Koen, Lemke, Lisker, Marietta, Maxted, Maxted, Mengel, Michaud, Michaud, Morales-Rueda, Napiwotzki, Napiwotzki, Napiwotzki, Napiwotzki, Napiwotzki, O’Donoghue, Pace, Peterson, Peterson, Peterson, Peterson, Politano, Przybilla, Quievy, Randall, Recio-Blanco, Recio-Blanco, S. Geier, Saffer, Sills, Silvotti, Soker, Ströer, Sweigart, Telting, U. Heber, Unglaub, van Grootel, van Grootel, Vink, Webbink, Østensen, Østensen   +98 more
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On the missing second generation AGB stars in NGC 6752 [PDF]

, 2014
In recent years the view of Galactic globular clusters as simple stellar populations has changed dramatically, it is now thought that basically all globular clusters host multiple stellar populations, each with its own chemical abundance pattern and ...
Cassisi, S, Monelli, M, Pietrinferni, A, Salaris, M, Vink, JS   +4 more
core   +2 more sources

Horizontal Branch stars as AmFm/HgMn stars

, 2008
CpAp Workshop Vienna, Austria, September ...
Michaud, G., Richer, J.
openaire   +2 more sources