On the intrinsic widths of the subgiant and horizontal branch sequences in the globular cluster M3
18
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
A new photometric study of M3 was done in order to obtain fine details of sequences in the bright part of the color-magnitude diagram from V = 12 to V = 17. Since the (B-V)o,g color of the subgiants is a function of metallicity at the level of the HB, the chemical homogeneity of the M3 stars was studied by finding the intrinsic width of the subgiant branch at the level of the horizontal branch. Limits were also sought for the intrinsic width of the horizontal branch. It was found that the subgiant branch may have zero intrinsic width in color, that the horizontal branch has an intrinsic width in magnitude of about 0.3 mag, presumably due to evolution, and that there is no definite proof for any gap in the giant branch other than that near V = 13.4, similar to that found earlier in M15, but discounted then.Keywords:
Subgiant
Horizontal branch
Blue straggler
Deep BV photometry for a large field covering the outer-halo globular cluster NGC 6229 is presented. For the first time, a colour-magnitude diagram (CMD) reaching below the main sequence turnoff has been obtained for this cluster. Previous results regarding the overall morphology of the horizontal and giant branches are confirmed. In addition, nine possible extreme horizontal-branch stars have been identified in our deep images, as well as thirty-three candidate blue stragglers. We also find the latter to be more centrally concentrated than subgiant branch stars covering the same range in V magnitude. A comparison of the cluster CMD with the M5 (NGC 5904) ridgeline from Sandquist et al. (1996) reveals that: i) NGC 6229 and M5 have essentially identical metallicities; ii) NGC 6229 and M5 have the same ages within the errors in spite of their different horizontal-branch morphologies.
Subgiant
Horizontal branch
Blue straggler
Red-giant branch
Cite
Citations (0)
Globular clusters are ideal laboratories to study the evolution of low‐mass stars. In this work we concentrate on three types of hot stars observed in globular clusters: horizontal branch stars, UV‐bright stars, and white dwarfs. After providing some historical background and information on gaps and blue tails, we discuss extensively hot horizontal branch stars in metal‐poor globular clusters, especially their abundance anomalies and the consequences for the determination of their atmospheric parameters and evolutionary status. Hot horizontal branch stars in metal‐rich globular clusters are found to form a small but rather inhomogeneous group that cannot be explained by one evolutionary scenario. Hot UV‐bright stars show a lack of classic post–asymptotic giant branch stars that may explain the lack of planetary nebulae in globular clusters. Finally, we discuss first results of spectroscopic observations of white dwarfs in globular clusters.
Horizontal branch
Blue straggler
Stellar collision
Asymptotic giant branch
Cite
Citations (75)
The globular-cluster metal-abundance parameter (B - V)/sub o,g,/ which is the intrinsic color index at the intersection of the horizontal and subgiant branch in the color-magnitude diagram, is shown to be tightly correlated with [Fe/ H]. (auth)
Subgiant
Horizontal branch
Color index
Cite
Citations (0)
The globular-cluster metal-abundance parameter, which is the intrinsic color index at the intersection of the horizontal and subgiant branch in the color-magnitude diagram, is shown to be tightly correlated with the concentration ratio of Fe/H.
Subgiant
Horizontal branch
Color index
Cite
Citations (7)
Deep BV photometry for a large field covering the outer-halo globular cluster NGC 6229 is presented. For the first time, a colour-magnitude diagram (CMD) reaching below the main sequence turnoff has been obtained for this cluster. Previous results regarding the overall morphology of the horizontal and giant branches are confirmed. In addition, nine possible extreme horizontal-branch stars have been identified in our deep images, as well as thirty-three candidate blue stragglers. We also find the latter to be more centrally concentrated than subgiant branch stars covering the same range in V magnitude.
A comparison of the cluster CMD with the M5 (NGC 5904) ridgeline from Sandquist et al. (1996) reveals that:
i) NGC 6229 and M5 have essentially identical metallicities;
ii) NGC 6229 and M5 have the same ages within the errors in spite of their different horizontal-branch morphologies.
Subgiant
Horizontal branch
Blue straggler
Red-giant branch
Cite
Citations (2)
Blue horizontal branch and UV bright stars in several globular clusters are analysed spectroscopically and the results are compared with predictions of stellar evolutionary theory. We find that the distribution of temperatures and surface gravities of the blue HB stars may be explained by the effects of deep mixing. The masses derived for these stars are too low unless one uses the long distance scale for globular clusters. First results on blue HB stars in metal rich clusters are presented. Analyses of hot UV bright stars in globular clusters uncovered a lack of genuine post-asymptotic giant branch stars which may explain the lack of planetary nebulae in globular clusters seen by Jacoby et al. (1997). Abundance analyses of post-AGB stars in two globular clusters suggest that gas and dust may separate during the AGB phase.
Blue straggler
Horizontal branch
Stellar collision
Asymptotic giant branch
Cite
Citations (4)
Abstract We present an extensive time-series radial-velocity (RV) survey of stars in the rich open cluster NGC 7789 (1.6 Gyr, [Fe/H] = +0.02). The stellar sample lies within an 18′ circular radius from the cluster center (10 pc in projection, or about 2 core radii), and includes giants, red clump stars, blue stragglers, red stragglers, sub-subgiants, and main-sequence stars down to 1 mag below the turnoff. Our survey began in 2005 and comprises more than 9000 RV measurements from the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. We identify 624 likely cluster members and present the orbital solutions for 81 cluster binary stars with periods between 1.45 and 4200 days. From the main-sequence binary solutions we fit a circularization period of days. We calculate an incompleteness-corrected main-sequence binary frequency of 31% ± 4% for binaries with periods less than 10 4 days, similar to other WIYN Open Cluster Survey (WOCS) open clusters of all ages. We detect a blue straggler binary frequency of 33% ± 17%, consistent with the similarly aged open cluster NGC 6819. We also find one secure, rapidly rotating sub-subgiant and one red straggler candidate in our sample.
Subgiant
Blue straggler
Radial velocity
Red clump
Red-giant branch
Cite
Citations (8)
Horizontal branch
Blue straggler
Cite
Citations (0)
Blue horizontal branch and UV bright stars in several globular clusters are analysed spectroscopically and the results are compared with predictions of stellar evolutionary theory. We find that the distribution of temperatures and surface gravities of the blue HB stars may be explained by the effects of deep mixing. The masses derived for these stars are too low unless one uses the long distance scale for globular clusters. First results on blue HB stars in metal rich clusters are presented.
Analyses of hot UV bright stars in globular clusters uncovered a lack of genuine post-asymptotic giant branch stars which may explain the lack of planetary nebulae in globular clusters seen by Jacoby et al. (1997). Abundance analyses of post-AGB stars in two globular clusters suggest that gas and dust may separate during the AGB phase.
Blue straggler
Horizontal branch
Stellar collision
Asymptotic giant branch
Cite
Citations (0)
In this work we present atmospheric parameters and Li abundances, obtained from a detailed spectroscopic analysis, for a large sample of stars with different evolutionary stages (turn-off, subgiant and giant stars) in the open cluster M67. The observations were carried out with high resolution (R ~ 47,000) and high S/N using the UVES+FLAMES at VLT/UT2. From available photometry and computed synthetic spectra for the region around the lithium line at 6707.75 Å, we derive atmospheric parameters (T eff , log g, [ Fe/H ], v sin i) and Li abundances for each star, in order to better understand the level of mixing and convective dilution of evolved stars in M67.
Subgiant
Blue straggler
Giant star
Asteroseismology
Cite
Citations (2)