CCD photometry in the globular cluster NGC 288. I - Blue stragglers and main-sequence binary stars

1992 ◽  
Vol 82 ◽  
pp. 145 ◽  
Author(s):  
Michael Bolte
Keyword(s):  
Globular Cluster ◽  
Binary Stars ◽  
Main Sequence ◽  
Ccd Photometry ◽  
Blue Stragglers

scholarly journals The Abundance of the LMC Globular Cluster NGC 2213

1988 ◽  
Vol 126 ◽  
pp. 579-580
Author(s):  
Doug Geisler
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
High Accuracy ◽  
Magellanic Cloud ◽  
New Technique ◽  
Distance Modulus ◽  
Ccd Photometry ◽  
Cloud Clusters ◽  
A New Technique ◽  
Using Data

A new technique for determining accurate abundances in distant giants - Washington CCD photometry - has been applied to the intermediate-age LMC globular cluster NGC 2213. An abundance of −0.40 ± 0.15 was found from the analysis of 42 giants with V < 20, using data obtained with the 1.5 m telescope. Combined with published main-sequence photometry, the derived abundance indicates a true LMC distance modulus of 18.2 ± 0.2. A likely CN strong giant near the tip of the giant branch is identified. Abundances are also derived for a sample of 27 field giants. Results indicate that one could determine both the age and abundance of Magellanic Cloud clusters with high accuracy from Washington photometry using the 4 m in less than one hour of observing time per cluster.

scholarly journals Pal 1: A Globular Cluster Anyway?

1995 ◽  
Vol 164 ◽  
pp. 395-395
Author(s):  
J. Borissova ◽  
N. Spassova
Keyword(s):  
Globular Cluster ◽  
Luminosity Function ◽  
Main Sequence ◽  
Structural Parameters ◽  
Distance Modulus ◽  
Horizontal Branch ◽  
Ccd Photometry ◽  
Horizontal Branch Stars ◽  
Mass Estimate

CCD photometry of the halo cluster Pall in Thuan-Gunn system is presented. The color - magnitude diagrams (Fig. 1) show a well defined red horizontal branch, lower giant branch and main-sequence down to about two magnitudes below the main-sequence turnoff. The giant branch is absent and the brightest stars are horizontal-branch stars. The horizontal branch is composed of red stars only. The age of the cluster, determined by comparison with the isochrones of Bell and Vanden Berg (1987) is consistent with an age between 12 – 14 Gyr. and a metallicity [Fe/H] = −0.79. The observed luminosity function shows a deficiency of stars from about 0.5 mag below turnoff up to g = 21 mag. A distance modulus of (m – M)g0 = 15.35 ± 0.1 magnitude has been derived. An estimate of the cluster structural parameters gives rc = 1.7 pc and c = 1.46. A mass estimate of 1.6 × 103M⊙ and mass-to-light ratio 1.77 has been obtained, using King's (1966) method.

scholarly journals CCD Photometry in the Globular Cluster M4

1995 ◽  
Vol 164 ◽  
pp. 411-411
Author(s):  
W.K. Griffiths ◽  
I.N. Kanatas ◽  
R.J. Dickens ◽  
A.J. Penny
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Ccd Photometry ◽  
Magnitude Diagram ◽  
Red Giant

A V, B- V composite colour-magnitude diagram, based upon CCD photometry from V~ 12 on the red giant branch to V~ 25 on the main-sequence has been derived for the globular cluster M4. A distance to the cluster of (m – M)v = 12.84 ± 0.19 is determined and the best match to theoretical isochrones is for the case [Fe/H]=−1.27 and an age of 16±1 Gyr. A differential age comparison with NGC 362 shows that M4 is approximately 1.7 Gyr older.

scholarly journals The Binary Fraction of NGC 6397

2007 ◽  
Vol 3 (S246) ◽  
pp. 263-264
Author(s):  
D. Saul Davis ◽  
Harvey B. Richer ◽  
Jay Anderson ◽  
James Brewer
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Dynamical Evolution ◽  
Computing Power ◽  
Blue Stragglers ◽  
The Core ◽  
Cluster Evolution ◽  
Key Parameter

AbstractThe binary fraction, η, of a globular cluster (GC) is a key parameter in determining its dynamical evolution, as well as its content of rare stars, such as cataclysmic variables and blue stragglers. The precise value of η for a GC was historically difficult to constrain due to an inability to obtain reliable photometry for faint objects in dense stellar fields. However, today, the HST allows us to image the main sequence of the nearest GCs to their terminations. Using HST observations we constrain η for NGC 6397. While the necessary computing power is now available to realistically simulate entire GCs, large discrepancies in the assumed primordial binary fraction, ηp, of GCs still exist. Estimates range from 5% (Hurley et al. 2007) to 100% (Ivanova et al. 2005). The N-body models of Hurley et al. (2007) suggest that η beyond the half-mass radius remains close to ηp, while cluster evolution can increase the value in the core. We find η for NGC 6397 is 15.2±0.8% in a field centered on the core, and 1.1±0.3% in a field beyond the half mass radius. These findings suggests ηp ~ 1%.

scholarly journals UBVI CCD Photometry of an old Open Cluster AM-2

1996 ◽  
Vol 169 ◽  
pp. 435-436 ◽  
Author(s):  
Myung Gyoon Lee
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Open Cluster ◽  
Ultraviolet Excess ◽  
Galactic Latitude ◽  
Ccd Photometry ◽  
Fitting Method ◽  
Age Ratio ◽  
Red Giant Clump ◽  
Red Giant

AM-2 is a sparse cluster located at low galactic latitude. It has been suspected to be a globular cluster. We present a study of AM-2 based on the deep UBVI CCD photometry obtained using the Las Campanas duPont 2.5m telescope. The color-magnitude diagrams of AM-2 show (a) a main-sequence extending up to V ≈ 19 mag at (B – V) ≈ 1.1 mag, (b) a small number of red giant clump giants, (c) the brightest red giant at V ≈ 16.1 mag and (B – V) ≈ 1.9 mag, and (d) a small group of mysterious blue stars at V ≈ 16.6 mag and (B – V) ≈ 0.9 mag. We have estimated the reddening using the color-color diagram, E(B – V) = 0.56 ± 0.04. The metallicity of the main-sequence stars has been estimated from the ultraviolet excess, δ(U – B)0.6 = 0.09 ± 0.04, to be [Fe/H] = −0.4 ± 0.2 dex. The distance to the cluster has been measured using the Zero-Age-Main-Sequence fitting method, (m – M)0 = 14.8 ± 0.3 (d = 9.1 ± 1.4 kpc). Finally we have estimated the age of the cluster using the Revised Yale isochrones and the Morphological Age Ratio (MAR) method, obtaining a value of 5 ± 1 Gyrs (Fig. 1). This shows that AM-2 is not a globular cluster, but an old open cluster.

scholarly journals Main-sequence CCD photometry of the globular cluster   Centauri

1991 ◽  
Vol 250 (2) ◽  
pp. 314-339 ◽  
Author(s):  
R. G. Noble ◽  
R. J. Dickens ◽  
J. Buttress ◽  
W. K. Griffiths ◽  
A. J. Penny
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Ccd Photometry

scholarly journals Unveiling the Core of M 15 in the Far-Ultraviolet

2007 ◽  
Vol 3 (S246) ◽  
pp. 361-362
Author(s):  
A. Dieball ◽  
C. Knigge ◽  
D. R. Zurek ◽  
M. M. Shara ◽  
K. S. Long ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Stellar Populations ◽  
Main Sequence Stars ◽  
Blue Stragglers ◽  
The Core ◽  
Near Ultraviolet ◽  
Horizontal Branch Stars ◽  
Far Ultraviolet

AbstractWe present an analysis of our deep far- (FUV) and near-ultraviolet (NUV) photometry of the core region of the dense globular cluster M 15. Our FUV-NUV colour-magnitude diagram (CMD) is the deepest one presented for a globular cluster so far, and shows all hot stellar populations expected in a globular cluster, such as horizontal branch stars, blue stragglers, white dwarfs, cataclysmic variables and even main sequence stars. The main sequence turn-off is clearly visible and the main sequence stars form a prominent track that extends at least two magnitudes below the main sequence turn-off. We compare and discuss the radial distribution of the various stellar populations that show up in the FUV. We search for variability amongst our FUV sources and tentatively classify our variable candidates based on an analysis of the UV colours and variability properties. We find that RR Lyraes, Cepheids, and SX Phoenicis exhibit massive variability amplitudes in this waveband (several mags).

BVI CCD photometry of the broad main-sequence globular cluster NGC 1851

1990 ◽  
Vol 99 ◽  
pp. 817 ◽  
Author(s):  
Gonzalo Alcaino ◽  
William Liller ◽  
Franklin Alvarado ◽  
Erich Wenderoth
Keyword(s):  
Globular Cluster ◽  
Main Sequence ◽  
Ccd Photometry
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