Far-Ultraviolet Luminosity Functions for the Globular Clusters M3 and M13

Whitney, J. H.; O’Connell, R. W.; Rood, R. T.; Hill, Ryley; Landsman, W. B.; Bohlin, R. C.; Roberts, M. S.; Smith, Andrew M.; Stecher, T. P.

doi:10.1086/117644

Cited by 6 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The UIT observations were subject to blending in the central regions and some candidates were rejected based on highresolution optical photometry, but in all cases it was possible to identify the stars that were the primary UV sources based on other photometry. In addition, some of the Whitney et al (1995) sources did not appear to have cluster counterparts at the tabulated positions. We do not have an explanation for this.…”

Section: Identification Of Evolutionary Statusmentioning

confidence: 88%

A Re-Evaluation of the Evolved Stars in the Globular Cluster M13

Sandquist

Gordon

Levine

et al. 2010

The Astronomical Journal

View full text Add to dashboard Cite

We have analyzed photometry from space-and ground-based cameras to identify all bright red giant branch (RGB), horizontal branch (HB), and asymptotic giant branch (AGB) stars within 10 ′ of the center of the globular cluster M13.We identify a modest (7%) population of HB stars redder than the primary peak (including RR Lyrae variables at the blue end of the instability strip) that is somewhat more concentrated to the cluster core than the rest of the evolved stars. We find support for the idea that they are noticeably evolved and in the late stages of depleting helium in their cores. This resolves a disagreement between distance moduli derived from the tip of the red giant branch and from stars in or near the RR Lyrae instability strip. We identified disagreements between HB model sets on whether stars with T eff 10000 K (near the "knee" of the horizontal branch in optical CMDs) should evolve redward or blueward, and the differences may depend on the inclusion of diffusion in the stellar interior. The sharp cut at the red end of M13's HB provides strong evidence that stars from the dominant HB group must still be undergoing blue loops, which implies that diffusion is being inhibited. We argue that M13's HB is a somewhat pathological casethe dominant HB population occurs very near the "knee" in optical CMDs, and evolved stars exclusively appear redward of that peak, leading to the incorrect appearance of a continuation of the unevolved HB.We identify two stars as "blue hook" star candidates -the faintest stars in optical bands that remain significantly subluminous in the shortest ultraviolet wavelength photometry available. M13 also has a distinct group of stars previously identified with the "second U jump". Based on far UV photometry, we find that these stars have genuinely high temperatures (probably 26000 K T eff 31000 K), and are not produced by a jump in brightness at lower temperature (T eff ≈ 22000 K) as previously suggested. These stars are brighter Subject headings: stars: AGB and post-AGB -stars: evolution -Hertzsprung-Russell and C-M diagrams -stars: horizontal branch -globular clusters: individual (M13) -ultraviolet: stars

show abstract

Section: Identification Of Evolutionary Statusmentioning

confidence: 88%

A Re-Evaluation of the Evolved Stars in the Globular Cluster M13

Sandquist

Gordon

Levine

et al. 2010

The Astronomical Journal

View full text Add to dashboard Cite

show abstract

“…The Galaxy contains more than 800 open clusters, which are primarily young, and 150 globular clusters, which are primarily old. Together, they span a broad range of stellar Parise et al 1994;Whitney et al 1994, 1995Hill et al 1996Dorman et al 1997O'Connell et al 1997Parise et al 1998Landsman et al 1996GALEX 200350 4071 4.3-5.3 1350-2800Lanzoni et al 2007Dalessandro et al 2009, 2012Schiavon et al 2012HST/FOC 1990-1999 .01-.05 0.01-0.04 1100-6500 Ferraro & Paresce 1993;Burgarella et al 1994HST/WFPC2 1993240 2.3-5.0 .04 1150-11000 Ferraro et al 1999, 2001Castellani et al 2006Sandquist et al 2010Brown et al 2010aDalessandro et al 2011 populations in both age and chemistry, as well as a variety of environments. Despite the extensive, excellent, and pioneering work cited above, frustrating gaps remain in our understanding of the UV properties of stellar populations and hot stars.…”

mentioning

confidence: 99%

THESWIFTUVOT STARS SURVEY. I. METHODS AND TEST CLUSTERS

Siegel

Porterfield

Linevsky

et al. 2014

View full text Add to dashboard Cite

We describe the motivations and background of a large survey of nearby stellar populations using the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-Ray Burst Mission. UVOT, with its wide field, near-UV sensitivity, and 2. ″3 spatial resolution, is uniquely suited to studying nearby stellar populations and providing insight into the near-UV properties of hot stars and the contribution of those stars to the integrated light of more distant stellar populations. We review the state of UV stellar photometry, outline the survey, and address problems specific to wide-and crowded-field UVOT photometry. We present color-magnitude diagrams of the nearby open clusters M67, NGC 188, and NGC 2539, and the globular cluster M79. We demonstrate that UVOT can easily discern the young-and intermediate-age main sequences, blue stragglers, and hot white dwarfs, producing results consistent with previous studies. We also find that it characterizes the blue horizontal branch of M79 and easily identifies a known post-asymptotic giant branch star.

show abstract

“…The properties of the most massive O-and B-type stars and the track of their post-main-sequence evolution are still poorly understood owing to their short lifetimes, uncertain distance scales, and the poorly constrained UV extinction law (see reviews in Zinnecker & Yorke 2007, Portegies Zwart et al 2010, and Langer 2012. Parise et al 1994;Whitney et al 1994, 1995Hill et al 1996Dorman et al 1997O'Connell et al 1997Parise et al 1998Landsman et al 1996GALEX 2003 2. Luminous Blue Variables and Wolf-Rayet Stars: The evolutionary stages between the O-star main sequence and supernovae are highly extremely luminous and have peak emission in the UV.…”

Section: Introduction: Stellar Populations In the Uvmentioning

confidence: 99%

The Swift UVOT Stars Survey: I. Methods and Test Clusters

Siegel,

Porterfield,

Linevsky

et al. 2014

Preprint

View full text Add to dashboard Cite

We describe the motivations and background of a large survey of nearby stellar populations using the Ultraviolet Optical Telescope (UVOT) aboard the Swift Gamma-Ray Burst Mission. UVOT, with its wide field, NUV sensitivity, and 2. ′′ 3 spatial resolution, is uniquely suited to studying nearby stellar populations and providing insight into the NUV properties of hot stars and the contribution of those stars to the integrated light of more distant stellar populations. We review the state of UV stellar photometry, outline the survey, and address problems specific to wide-and crowded-field UVOT photometry. We present color-magnitude diagrams of the nearby open clusters M 67, NGC 188, and NGC 2539, and the globular cluster M 79. We demonstrate that UVOT can easily discern the youngand intermediate-age main sequences, blue stragglers, and hot white dwarfs, producing results consistent with previous studies. We also find that it characterizes

show abstract

Far-Ultraviolet Luminosity Functions for the Globular Clusters M3 and M13

Cited by 6 publications

References 0 publications

A Re-Evaluation of the Evolved Stars in the Globular Cluster M13

A Re-Evaluation of the Evolved Stars in the Globular Cluster M13

THESWIFTUVOT STARS SURVEY. I. METHODS AND TEST CLUSTERS

The Swift UVOT Stars Survey: I. Methods and Test Clusters

Contact Info

Product

Resources

About