On the interpretation of the Sandage period-shift effect among globular-cluster RR Lyrae variables

1987 ◽  
Vol 312 ◽  
pp. 762 ◽  
Author(s):  
Allen V. Sweigart ◽  
Alvio Renzini ◽  
Amedeo Tornambe
Keyword(s):  
Globular Cluster ◽  
Rr Lyrae ◽  
Period Shift ◽  
Shift Effect

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 CCD Photometry of RR Lyrae Stars in M3

1993 ◽  
Vol 139 ◽  
pp. 325-331
Author(s):  
C. Cacciari ◽  
E. Carretta ◽  
F. Ferraro ◽  
F. Fusi Pecci ◽  
G. Tessicini ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Ccd Photometry ◽  
Rr Lyrae Stars ◽  
Preliminary Results ◽  
Rr Lyrae ◽  
Period Shift ◽  
Shift Effect ◽  
Lyrae Stars

AbstractNew CCD BVI observations of RR Lyrae variables in M3 are presented. Mean magnitudes and colours are derived, as well as their relations with periods and amplitudes, and comparisons are made with previous data (Sandage 1981, 1990). Preliminary results are presented on the temperature distribution of the variables and the period-shift effect with respect to M15 and M68.

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.

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

On the mixed-mode RR lyrae variables in the globular cluster Ic 4499

1987 ◽  
pp. 230-232 ◽  
Author(s):  
Christine M Clement ◽  
James M Nemec ◽  
R J Dickens ◽  
Elizabeth A Bingham
Keyword(s):  
Globular Cluster ◽  
Mixed Mode ◽  
Rr Lyrae

scholarly journals A Century in Period Changes of the Variables in M15

1995 ◽  
Vol 155 ◽  
pp. 387-388
Author(s):  
Katalin Barlai ◽  
B. Szeidl
Keyword(s):  
Globular Cluster ◽  
Period Change ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Linear Period

AbstractPeriod behaviour of 62 RR Lyrae stars in the M15 globular cluster has been investigated. About one half of the sample (30 stars) exhibited linear period change. The remaining 32 variables can be characterized by abrupt or erratic changes in their periods.

scholarly journals CCD Observations of Variable Stars in Globular Clusters

1989 ◽  
Vol 111 ◽  
pp. 285-285
Author(s):  
H.A. Smith ◽  
J.R. Kuhn ◽  
J. Curtis
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Variable Stars ◽  
Michigan State University ◽  
State University ◽  
Ccd Photometry ◽  
Rr Lyrae ◽  
Short Period ◽  
Ccd Observations ◽  
Period Variable

AbstractBVR observations of the relatively metal-rich globular cluster NGC 6388 have been obtained with a CCD on the CTIO 0.9 m telescope. Eighteen possible short period variable stars have been discovered in or near the cluster. At least 10 of these are probable RR Lyrae members of NGC 6388. We confirm the finding of Hazen and Hesser that this cluster is one of the most metal-rich to contain a significant number of RR Lyraes. A program of CCD photometry of field and cluster variable stars has been initiated on the 0.6m telescope of the Michigan State University Observatory.

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