M75, A Globular Cluster with a Trimodal Horizontal Branch. II.BVPhotometry of the RR Lyrae Variables

2003 ◽  
Vol 125 (5) ◽  
pp. 2543-2558 ◽  
Author(s):  
T. M. Corwin ◽  
M. Catelan ◽  
H. A. Smith ◽  
J. Borissova ◽  
F. R. Ferraro ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Horizontal Branch ◽  
Rr Lyrae

scholarly journals The Influence of Rotation on Horizontal Branch Stars and on RR Lyrae Pulsational Properties

1981 ◽  
Vol 93 ◽  
pp. 275-275
Author(s):  
V. Castellani
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Horizontal Branch ◽  
Structural Variations ◽  
Rr Lyrae ◽  
Horizontal Branch Stars ◽  
Mass Size ◽  
Red Giant

The occurrence of rotation in Globular Cluster stars has been suggested (see e.g. Renzini 1977) as a mechanism producing the observed colour spread in actual Horizontal Branches. If this is the case, canonical results on evolutionary properties of HB stars have to be revisited in order to account for rotation-driven structural variations: faster Main Sequence rotators delay the He flash increasing the mass-size Mc of the He core at the flash and loosing a greater amount of mass during the Red Giant stage.

scholarly journals The Globular Cluster ω Centauri and its RR Lyrae Variables

1989 ◽  
Vol 111 ◽  
pp. 141-167
Author(s):  
R.J. Dickens
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Red Giants ◽  
Horizontal Branch ◽  
Main Sequence Stars ◽  
Chemical Enrichment ◽  
Rr Lyrae ◽  
Stellar Pulsation ◽  
Stellar Ages ◽  
Period Shift

AbstractThe significance of some of the unusual characteristics of the globular cluster ω Centauri in various fundamental problems is explored. Interest is centred on the properties of the cluster RR Lyraes, and what they can contribute to studies of early cluster chemical enrichment, stellar pulsation, the distance scale, stellar evolution, stellar ages and the Oosterhoff period-shift problem. This article, which is intended to highlight problems and progress rather than give a comprehensive review, includes new results based on photometry of the RR Lyraes, red giants, subgiants, horizontal-branch and main sequence stars in the cluster.

scholarly journals Period Changes of RR Lyrae Stars in the LMC Globular Cluster NGC 2257

1984 ◽  
Vol 108 ◽  
pp. 39-40 ◽  
Author(s):  
James M. Nemec ◽  
Martha H. Liller ◽  
James E. Hesser
Keyword(s):  
Physical Properties ◽  
Globular Cluster ◽  
Period Change ◽  
Stellar Systems ◽  
Horizontal Branch ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Horizontal Branch Stars ◽  
Lyrae Stars

The period changes of RR Lyrae stars can be compared with models of horizontal branch stars as a means of investigating the physical properties of the stars themselves, and of the stellar systems in which they are found (Smith and Sandage 1981). The present study is the first in which period change rates of extragalactic RR Lyraes have been estimated.

scholarly journals The Instability Strip of M3

2000 ◽  
Vol 176 ◽  
pp. 255-256 ◽  
Author(s):  
G. Á. Bakos ◽  
J. Jurcsik
Keyword(s):  
Globular Cluster ◽  
Horizontal Branch ◽  
Instability Strip ◽  
Ccd Photometry ◽  
Perfect Agreement ◽  
Rr Lyrae Stars ◽  
Precise Position ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Theoretical Results

AbstractWe present new multicolour CCD photometry of the central part of the globular cluster M3, mapping the precise position of ~ 120 RR Lyrae stars (RRab, RRd, RRc) on the horizontal branch (HB). The location of the double-mode variables (RRd) is in perfect agreement with recent theoretical results. We find a significant internal spread of metallicity amongst the RRab variables.

scholarly journals The Variable Stars in NGC 6723

1973 ◽  
Vol 21 ◽  
pp. 178-179
Author(s):  
John Menzies
Keyword(s):  
Southern Hemisphere ◽  
Globular Cluster ◽  
Variable Stars ◽  
Horizontal Branch ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Horizontal Branch Stars ◽  
Magnitude Diagram ◽  
The Mean ◽  
Lyrae Stars

Abstract*.A study has been made of the variables in the Southern Hemisphere globular cluster NGC 6723, which is suspected of being relatively metal-rich on the basis of its colour-magnitude diagram and of its integrated spectral type of G3. Seven new RR Lyrae stars and two bright red, probably semiregular, variables have been found and the suspected variable of Fourcade and Laborde has been confirmed. The complement of RR Lyrae stars is now 27, consisting of 4 c-type and 23 ab-type variables, the mean periods being Pc = 0.d292 and Pab = 0.d537. On the basis of the two-colour diagram of the horizontal branch stars the cluster is considered to be virtually un-reddened. Applying Christy’s models to the data from this study we find the following parameters for the variables: Mv= 1.m10, mass = 0.42 M⊙, and Y=0.4.

UBV Photometry of RR Lyrae Variables in the Globular Cluster M4

1979 ◽  
Vol 46 ◽  
pp. 347-354 ◽  
Author(s):  
Carla Cacciari
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Normal Metal ◽  
Red Giants ◽  
The Sun ◽  
Horizontal Branch ◽  
Dark Clouds ◽  
Rr Lyrae ◽  
Metal Abundance ◽  
Ubv Photometry

M4, one of the closest globular clusters to the Sun, presents some peculiar features that make it very interesting to study. The first C-M diagram, published by Greenstein (1939), showed a well populated blue-horizontal branch, a characteristic which usually, but not always, indicates low metal abundance (Hartwick 1968). Kinman (1959) found however that it contains strong lined red giants and classified it as type A, indicating normal metal abundance. More recent C-M diagrams (Moshkalev 1975, Alcaino 1975, Lee 1977, Lloyd Evans 1977) substantially confirmed both these characteristics.One of the major problems in the study of this cluster is the high and possibly non-uni form reddening, due to its location behind the Scorpius-Ophiuchus dark clouds.

scholarly journals Discovery of More than 200 RR Lyrae Variables in M62: An Oosterhoff I Globular Cluster with a Predominantly Blue Horizontal Branch

2005 ◽  
Vol 623 (2) ◽  
pp. L117-L120 ◽  
Author(s):  
R. Contreras ◽  
M. Catelan ◽  
Horace A. Smith ◽  
Barton J. Pritzl ◽  
J. Borissova
Keyword(s):  
Globular Cluster ◽  
Horizontal Branch ◽  
Rr Lyrae

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

scholarly journals The RR Lyrae variables in the globular cluster M68

1993 ◽  
Vol 412 ◽  
pp. 183 ◽  
Author(s):  
Christine M. Clement ◽  
Stephen Ferance ◽  
Norman R. Simon
Keyword(s):  
Globular Cluster ◽  
Rr Lyrae
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