Analysis of evolutionary period-shift predictions for RR Lyrae stars in Galactic globular clusters

1993 ◽  
Vol 106 ◽  
pp. 175 ◽  
Author(s):  
M. Catelan ◽  
J. A. de Freitas Pacheco
Keyword(s):  
Globular Clusters ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Period Shift ◽  
Galactic Globular Clusters ◽  
Lyrae Stars

scholarly journals RR Lyrae Stars in Galactic Globular Clusters. II. A Theoretical Approach to Variables in M3

2003 ◽  
Vol 596 (1) ◽  
pp. 299-313 ◽  
Author(s):  
M. Marconi ◽  
F. Caputo ◽  
M. Di Criscienzo ◽  
M. Castellani
Keyword(s):  
Theoretical Approach ◽  
Globular Clusters ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Galactic Globular Clusters ◽  
Lyrae Stars

scholarly journals RR Lyrae stars in Galactic globular clusters

2007 ◽  
Vol 476 (2) ◽  
pp. 779-790 ◽  
Author(s):  
G. Bono ◽  
F. Caputo ◽  
M. Di Criscienzo
Keyword(s):  
Globular Clusters ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Galactic Globular Clusters ◽  
Lyrae Stars

scholarly journals RR Lyrae Stars and the Sandage Period-Shift Effect Examined Using IR-Derived Temperatures

1989 ◽  
Vol 111 ◽  
pp. 274-274
Author(s):  
A.J. Longmore ◽  
R. Dixon ◽  
I. Skillen ◽  
R.F. Jameson ◽  
J.A. Fernley
Keyword(s):  
Globular Clusters ◽  
Log P ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Period Shift ◽  
Observational Errors ◽  
Shift Effect ◽  
Few Data ◽  
Lyrae Stars ◽  
Temperature Amplitude

AbstractMean temperatures for RR Lyrae stars in 7 globular clusters (M3, M4, M5, M15, M107, ω Cen and NGC 5466) have been determined using the optical-infrared colour <V>-<K> as a temperature indicator. Where <K> has been relatively well determined, from means of 3 or more observations, the scatter in relationships such as Log P’ vs log (temperature) and log (temperature) vs (blue amplitude) is significantly reduced when IR-derived temperatures are used instead of those derived from (B-V). Within the observational errors, the gradient in the log P’ vs log (temperature) diagram is the same for each cluster. Temperatures derived from <V>-<K> should also be less sensitive to metallicity differences than their optically derived counterparts. The Sandage Period-Shift Effect has therefore been re-examined using 6 of the 7 clusters (NGC 5466 was excluded because of too few data). A strong correlation between period-shift and metallicity is found; a smaller shift (but in the same sense) is also found for the temperature – amplitude relationship.

scholarly journals General Properties of the Two Groups of Globular Clusters and Their Variable Stars

1975 ◽  
Vol 67 ◽  
pp. 541-543
Author(s):  
A. V. Mironov ◽  
N. N. Samus'
Keyword(s):  
Chemical Composition ◽  
Globular Clusters ◽  
Variable Stars ◽  
Rr Lyrae Stars ◽  
General Properties ◽  
Rr Lyrae ◽  
Lyrae Stars

The dependences of the numbers of variable stars in globular clusters on the chemical composition are studied. For given metallicity the numbers of RR Lyrae stars reduced to some definite total number of stars in the cluster are different for the two groups of globular clusters introduced by Mironov.

On the Two Oosterhoff Groups of Globular Clusters

1973 ◽  
Vol 21 ◽  
pp. 196-196
Author(s):  
T. S. Van Albada ◽  
Norman Baker
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Transition Point ◽  
Transition Period ◽  
Observational Evidence ◽  
Horizontal Branch ◽  
Average Difference ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

AbstractThe observational evidence leading to the classification, following Oosterhoff, of globular clusters containing RR Lyrae stars into two distinct groups, is summarized and discussed in the light of results of stellar evolution theory and pulsation theory. The dichotomy is caused, at least in part, by a dichotomy in the ‘transition period’ between the type-ab and type-c stars which reflects a difference in effective temperature at the transition point. When this difference is accounted for, there remains a smaller average difference between the groups, though no longer a clear dichotomy, that is probably a mass and luminosity effect. If this remaining difference is interpreted as a luminosity effect the average difference in luminosity between the two Oosterhoff groups is at most 0.1 mag. It is suggested that Christy’s theoretical relationship between transition period and luminosity cannot be valid, at least not for clusters of different Oosterhoff groups. It is conjectured that the transition-temperature dichotomy may be a reflection of different predominant directions of evolution along the horizontal branch, accompanied by a hysteresis effect in the pulsations.

scholarly journals Search for Variables in the Galactic Globular Clusters NGC 6544 and NGC 6642

1993 ◽  
Vol 139 ◽  
pp. 337-337
Author(s):  
Martha L. Hazen
Keyword(s):  
Globular Clusters ◽  
Slow Variable ◽  
Variable Stars ◽  
Horizontal Branch ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
A Value ◽  
Short Period ◽  
Period Variable ◽  
Lyrae Stars

A search for variable stars in the globular cluster NGC 6544 has revealed only one possible short period variable within the tidal radius of the cluster. A search in NGC 6642 yielded 16 new RR Lyrae stars within the tidal radius and 5 new field RRs. The previously discovered (Hoffleit 1972) V1 is a slow variable, and V2 is an RR Lyrae star. Photometry of the variables within the tidal radius gives a mean B for the horizontal branch of < B > = 17.0 mag. With E(B – V) = 0.37 mag and (B – V) = 0.35 mag for RR Lyraes, a value for V(HB) = 16.3 mag is derived. This is about one mag fainter than previous estimates (Webbink 1985), and places NGC 6642 at a distance of approximately 7.9 kpc.

K-band light curves for RR Lyrae stars in the globular clusters M5 and M92

1992 ◽  
Vol 104 ◽  
pp. 159 ◽  
Author(s):  
Jesper Storm ◽  
Bruce W. Carney ◽  
David W. Latham
Keyword(s):  
Globular Clusters ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
K Band
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