Globular Cluster Photometry near the Turnoff: Blue Stragglers, Relative Ages, and the Horizontal Branch

1994 ◽  
Vol 106 ◽  
pp. 205 ◽  
Author(s):  
Ata Sarajedini
Keyword(s):  
Globular Cluster ◽  
Horizontal Branch ◽  
Blue Stragglers

Blue stragglers in the core of the globular cluster 47 Tucanae

Nature ◽  
1991 ◽  
Vol 352 (6333) ◽  
pp. 297-301 ◽  
Author(s):  
F. Paresce ◽  
M. Shara ◽  
G. Meylan ◽  
D. Baxter ◽  
P. Greenfield ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Blue Stragglers ◽  
The Core

scholarly journals Hubble Space TelescopeObservations of NGC 121: First Detection of Blue Stragglers in an Extragalactic Globular Cluster

1998 ◽  
Vol 508 (2) ◽  
pp. 570-575 ◽  
Author(s):  
Michael M. Shara ◽  
S. Michael Fall ◽  
R. Michael Rich ◽  
David Zurek
Keyword(s):  
Globular Cluster ◽  
Blue Stragglers

Supra–Horizontal‐Branch Stars and Population Gradients in the Galactic Center Globular Cluster NGC 6522

1998 ◽  
Vol 495 (2) ◽  
pp. 796-803 ◽  
Author(s):  
M. M. Shara ◽  
L. Drissen ◽  
R. M. Rich ◽  
F. Paresce ◽  
I. R. King ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Galactic Center ◽  
Horizontal Branch ◽  
Horizontal Branch Stars

scholarly journals Two PopII Cepheids in the Globular Cluster M10

1985 ◽  
Vol 82 ◽  
pp. 260-261 ◽  
Author(s):  
C. Clement ◽  
H. Sawyer Hogg ◽  
K. Lake
Keyword(s):  
Globular Cluster ◽  
Horizontal Branch ◽  
Carnegie Institution ◽  
University Of Toronto ◽  
The Third ◽  
Irregular Variable ◽  
Carnegie Institution Of Washington ◽  
The University

The globular cluster Messier 10 has three known variables. The first two of these were discovered by one of us (Sawyer 1933) and the third by Arp (1955). Two of the variables, V2 (P=18.7226) and V3 (P=7.831), are population II cepheids while V1 appears to be an irregular variable. Another star which lies in the Schwarzschild gap on the horizontal branch is a suspected variable (Voroshilov 1971).In this investigation, we examine the variations in the periods of the two cepheids over the interval 1912 to 1983 (for V2) and 1931 to 1983 (for V3). The study is based on photographs obtained with seven different telescopes - the Mt.Wilson 100-inch and 60-inch (1912 to 1919), the Dominion Astrophysical Observatory 72-inch, the David Dunlap 74-inch and 19-inch, the 16-inch at the University of Toronto downtown campus and the University of Toronto 24-inch at the Las Campanas Observatory of the Carnegie Institution of Washington. Some of our magnitudes have already been published (Sawyer 1938) and the remaining ones will be submitted to the Astronomical Journal for publication. We have also included material published by Arp (1955, 1957) in our study.

scholarly journals The HST large programme on NGC 6752 – III. Detection of the peak of the white dwarf luminosity function

2019 ◽  
Vol 488 (3) ◽  
pp. 3857-3865
Author(s):  
L R Bedin ◽  
M Salaris ◽  
J Anderson ◽  
M Libralato ◽  
D Apai ◽  
...  
Keyword(s):  
Globular Cluster ◽  
White Dwarf ◽  
Luminosity Function ◽  
Main Sequence ◽  
Hubble Space Telescope ◽  
Horizontal Branch ◽  
Space Telescope

ABSTRACT We report on the white dwarf (WD) cooling sequence of the old globular cluster NGC 6752, which is chemically complex and hosts a blue horizontal branch. This is one of the last globular cluster WD cooling sequences accessible to imaging by the Hubble Space Telescope. Our photometry and completeness tests show that we have reached the peak of the luminosity function of the WD cooling sequence, at a magnitude mF606W  = 29.4 ± 0.1, which is consistent with a formal age of ∼14 Gyr. This age is also consistent with the age from fits to the main-sequence turn-off (13–14 Gyr), reinforcing our conclusion that we observe the expected accumulation of WDs along the cooling sequence.

scholarly journals Evidence for Mass Segregation in NGC 5466

1988 ◽  
Vol 126 ◽  
pp. 677-678
Author(s):  
James M. Nemec ◽  
Hugh C. Harris
Keyword(s):  
Globular Cluster ◽  
Binary Systems ◽  
Low Frequency ◽  
Close Binary ◽  
Photoelectric Photometry ◽  
Significance Level ◽  
Blue Stragglers ◽  
Mass Segregation ◽  
The Masses ◽  
Subgiant Stars

Forty-eight blue straggler stars have been discovered in NGC 5466, the only Galactic globular cluster known to contain an anomalous Cepheid of the sort found in dwarf galaxies. The stars were identified in color-magnitude diagrams constructed from photometry of deep photographic plates taken with the Canada-France-Hawaii 3.6 m telescope (calibrated with new UBV photoelectric photometry), and from point spread function photometry of CCD frames taken with the Palomar 5 m telescope. The stars typically have magnitudes <V> ~ 19.m1 and colors <B-V> ~ 0.m2. Forty-two of the 48 stars are situated inside of R=2.5 arcmin (see Fig.1), the projected radius containing half the cluster luminosity, and only six stars are found between 2.5 and 9 arcmin. A one-sided, two-sample Kolmogorov-Smirnov test (using the CCD data) establishes at the 98% significance level that the blue stragglers are more centrally concentrated than the subgiant stars of the same magnitude. By fitting multi-component King models to the projected radial distributions (Fig.2), the mean mass of the blue stragglers is shown to be ~1.5 to two times larger than the masses of the stars that contributed the light from which the core and tidal radii were derived (i.e. M (Blue Str.)=1.3±0.3 M⊙). Because the central relaxation time for NGC 5466 is much less than the cluster age, the different radial distributions are attributed to mass segregation. A similar mass segregation is also observed in the globular cluster NGC 5053, where Nemec and Cohen (1986, in preparation) have recently identified ~30 blue stragglers. The low stellar density and small escape velocity of NGC 5466 make a recent epoch of star formation (during which the blue stragglers might have formed as massive single stars) seem unlikely. Instead, the blue stragglers probably are either close binary systems that have transferred mass, or are coalesced stars. The very low frequency of stellar collisions expected in the center of NGC 5466 suggests that the blue stragglers are primordial binary systems. The simultaneous presence in NGC 5466 of the blue stragglers and the anomalous Cepheid V19, and their relative numbers, supports the hypothesis that there is an evolutionary connection between the two types of stars. By fitting theoretical isochrones to the photographic c-m diagram, NGC 5466 is estimated to have an age of 18±3 Gyr.

scholarly journals Multivariate analysis of globular cluster horizontal branch morphology: searching for the second parameter

2006 ◽  
Vol 452 (3) ◽  
pp. 875-884 ◽  
Author(s):  
A. Recio-Blanco ◽  
A. Aparicio ◽  
G. Piotto ◽  
F. De Angeli ◽  
S. G. Djorgovski
Keyword(s):  
Multivariate Analysis ◽  
Globular Cluster ◽  
Horizontal Branch ◽  
Branch Morphology

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
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