Two-color photographic photometry of variables in the globular cluster M28

1990 ◽  
Vol 100 ◽  
pp. 686 ◽  
Author(s):  
Amelia Wehlau ◽  
Steven Butterworth
Keyword(s):  
Globular Cluster ◽  
Photographic Photometry

scholarly journals Photographic photometry of RR Lyrae variables in the globular cluster M15

1984 ◽  
Vol 209 (4) ◽  
pp. 765-824 ◽  
Author(s):  
E. A. Bingham ◽  
C. Cacciari ◽  
R. J. Dickens ◽  
F. Fusi Pecci
Keyword(s):  
Globular Cluster ◽  
Rr Lyrae ◽  
Photographic Photometry

C-M diagram and luminosity function of the Galactic globular cluster NGC 7099. I - Photographic photometry

1987 ◽  
Vol 94 ◽  
pp. 360 ◽  
Author(s):  
Giampaolo Piotto ◽  
Massimo Capaccioli ◽  
Sergio Ortolani ◽  
Leonida Rosino ◽  
Gonzalo Alcaino ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Luminosity Function ◽  
Photographic Photometry

scholarly journals The Main Sequence of the Very Old Globular Cluster NGC 6397

1980 ◽  
Vol 85 ◽  
pp. 423-423
Author(s):  
Gonzalo Alcaino ◽  
William Liller
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Main Sequence ◽  
Narrow Range ◽  
Age Determination ◽  
The Sun ◽  
Age Of The Universe ◽  
The Universe ◽  
Photographic Photometry ◽  
Collapse Phase

We present photographic photometry for 1135 stars in the globular cluster NGC 6397, which, at a distance of 2.4 kpc, is most likely the second nearest globular to the Sun. The Racine wedge with the CTIO Yale 1 m telescope (Δm=3. 60 mag), the CTIO 4 m telescope (Δm=6. 83 mag) and the ESO 3.6 m telescope (Δm=3. 87 mag) was used to extend the photoelectric calibration from V≃16.1 to V≃20.7. The main sequence turnoff at V=16.7 and B-V=0.52 with respectively Mv =4.30 and (B-V)o =0.36 yields (m-M)v=12.40 and E(B-V)=0.16. Using the models of Iben and Rood (1970) and the isochrones of Demarque and McClure (1977), we deduce the cluster's age to be 17 × 109 years. This makes this object the oldest of the nine globular clusters with age determination and gives a lower limit to the age of the universe, rendering Ho ≤ 57 km sec−1 Mpc−1 if qo ≥ 0 is assumed. The large age spread of 6 billion years between NGC 6397 and 47 Tuc (the youngest counterpart with age data) indicates both that the protogalaxy underwent a slow collapse phase and that the abundances in globular clusters are lower for the oldest. The fact that the galactocentric distances for these clusters have the narrow range of 6 <R < 13 kpc makes it highly important to secure age data for extremely metal poor globulars far out in the halo.

scholarly journals Variable Stars In NGC 4590

1973 ◽  
Vol 21 ◽  
pp. 76-81
Author(s):  
A. Terzan ◽  
B. Rutily ◽  
CH. Ounnas
Keyword(s):  
Globular Cluster ◽  
Variable Stars ◽  
List Type ◽  
Image Tube ◽  
European Southern Observatory ◽  
Photographic Photometry

AbstractThe globular cluster NGC 4590 has been observed at Haute Provence Observatory (photographic photometry, 80-cm reflector, F/6) and at the European Southern Observatory (image-tube, 152-cm reflector, F/15). – A sequence of red magnitudes, mr (λett ≅ 6400 Å) has been established around the cluster. It comprises 28 stars with magnitudes between 11.66 and 16.50.– Five new variable stars were discovered in a one square degree field, centered on the cluster.– Four other variable stars (No. 39, 40, 41, and 42) were discovered in the cluster.

scholarly journals The Distribution of the RR Lyrae Variables in ω Centauri and Background Light

1995 ◽  
Vol 155 ◽  
pp. 389-390
Author(s):  
J. O. Petersen ◽  
M. Andersen
Keyword(s):  
Central Region ◽  
Globular Cluster ◽  
Angular Distance ◽  
Rr Lyrae Stars ◽  
Background Light ◽  
Rr Lyrae ◽  
Low Amplitude ◽  
Lyrae Stars ◽  
Photographic Photometry

AbstractThe distribution of the RR Lyrae stars in the globular cluster ω Centauri is studied, using the data published by Martin in 1938. Comparing the accumulated numbers of variables within the angular distance, r, from the centre of the cluster, it is shown that the known RRc variables seem to be less concentrated towards the centre than the RRab stars. 6-10 RRc stars are missing within r = 2–3 arcmin, if the two distributions are actually identical, as expected from evolution models. We conclude that the central region may contain several RRc stars that have not yet been discovered. This could be due to their relatively low amplitude, since it is very difficult to find low-amplitude variables by means of photographic photometry in the crowded, central region of ω Cen with large and varying corrections due to unresolved background light.

scholarly journals A Photoelectric Investigation of the Eclipsing Binary V 78 in Omega Centauri (NGC 5139)

1971 ◽  
Vol 15 ◽  
pp. 235-237
Author(s):  
Edward H. Geyer
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Variable Star ◽  
Eclipsing Binaries ◽  
Stellar Systems ◽  
Light Elements ◽  
Eclipsing Binary ◽  
Evolved Stars ◽  
Photographic Photometry ◽  
Highly Evolved

The existence of eclipsing binaries, though extremely rare, in stellar systems like globular clusters, should attract the observers, because one could obtain fundamental data on highly evolved stars. The variable star V 78 in the globular cluster NGC 5139, which was found by BAILEY (1901), is one of these rare cases. MARTIN (1938) derived the period P = 1ḍ168118, and showed by means of an extensive photographic photometry that it is an Algol type eclipsing binary. Recently SISTERO et al. (1968, 1969) rediscussed the observations of MARTIN, and with additional measurements derived the following light elements:

47 Tuc

1967 ◽  
Vol 1 (1) ◽  
pp. 16-16
Keyword(s):  
Globular Cluster ◽  
Ultraviolet Excess ◽  
Horizontal Branch ◽  
Photographic Photometry

Wildey (1961) and Tifft (1963) have both done photographic photometry in two colours of 47 Tuc. They found a colour-magnitude (c-m) relation which is characterized by a very short red horizontal branch and a giant branch which is redder at a given magnitude and fainter at a given colour than that of any other globular cluster. Eggen (1961) obtained an ultraviolet excess of 0m.19 for 8 cluster members bluer than B-V = 1m.4 and of 0m.21 for 7 stars redder than this, assuming negligible reddening for the cluster.

scholarly journals The main-sequences of NGCs 2 88, 3201, 4590, and 6809

1984 ◽  
Vol 105 ◽  
pp. 157-158
Author(s):  
A.J. Penny
Keyword(s):  
Stellar Evolution ◽  
Globular Cluster ◽  
Fair Agreement ◽  
Number Of Clusters ◽  
Gravitational Settling ◽  
Preliminary Results ◽  
Theoretical Investigations ◽  
Magnitude Diagram ◽  
Ccd Observations ◽  
Photographic Photometry

A globular cluster is an admirable object for the study of stellar evolution and theoretical investigations of the isochrones in the colour-magnitude diagram (CMD) have been numerous, with the most recent being that of Vandenberg (1983, Ap. J. Suppl. 51, 29), but there are still uncertainties such as rotation, abundance variations and gravitational settling. The matching observations are in fair agreement. However only a small number of clusters have been observed and the detailed matching is poor. Most of the CMDs are from photoelectrically calibrated photographic photometry which are affected by the variable background found in clusters. Modern detectors suffer less from this problem and are very sensitive. A programme has been underway on a number of clusters using electronographs and CCDs with the SAAO 1.Om telescope and the crowded-field Starlink Aspic software. This paper reports on preliminary results from four of the clusters. The CCD observations were done in collaboration with W.K. Griffiths of Leeds University.

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

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.

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