Color-Magnitude Diagram and Luminosity Function of M4 near the Hydrogen-burning Limit

Bedin, L. R.; Anderson, Jay; King, Ivan R.; Piotto, G.

doi:10.1086/324174

Cited by 54 publications

(52 citation statements)

References 9 publications

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“…Keeping all this in mind, we simply fix the coordinates in the WFI catalog and estimate the displacement of the NTT data, that are separated by 8 years. Following Bedin et al (2001) we show the proper motion and colour-magnitude diagram of this comparison.…”

Section: Proper Motion and Membership Confirmationmentioning

confidence: 99%

VLT-UVES analysis of two giants in the bulge metal-poor globular cluster HP-1

Barbuy¹,

Zoccali

Ortolani³

et al. 2006

A&A

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AstrophysicsVLT-UVES analysis of two giants in the bulge metal-poor globular cluster HP-1 ABSTRACTContext. Metal-poor globular clusters in the bulge are important tracers of early chemical evolution. HP-1 is among the six metal-poor clusters within 5• of the Galactic center, and could be the one closest to the center Aims. The main purpose of this study is the determination of metallicity and elemental ratios. Methods. High resolution spectra of two giants of the bulge globular cluster HP-1 were obtained at the 8 m VLT UT2-Kueyen telescope with the UVES spectrograph. This is the second metal-poor globular cluster in the bulge for which a detailed abundance analysis is presented. Multiband V, I, J, H, K s photometry was used to derive effective temperatures.Results. The present analysis provides a metallicity [Fe/H] = −1.00 ± 0.2. The α-elements oxygen and silicon show [α/Fe] ≈ +0.3, whereas magnesium, calcium and titanium show solar ratios. A proper motion analysis indicates that the two stars are cluster members. Conclusions. The metallicity is unexpected for a blue Horizontal Branch (BHB) cluster. HP-1 is the first known cluster with such a high metallicity combined with a BHB and a steep Red Giant Branch (RGB). Together with NGC 6388 and NGC 6441 of [Fe/H] ∼ −0.6 it would be third with such characteristics, but it differs from them, since these two other clusters have also a populous Red HB, and a normal slope of the RGB for their metallicity, which is not the case of HP-1.

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Section: Proper Motion and Membership Confirmationmentioning

confidence: 99%

VLT-UVES analysis of two giants in the bulge metal-poor globular cluster HP-1

Barbuy¹,

Zoccali

Ortolani³

et al. 2006

A&A

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“…These two fields were imaged for 11,800 s in F336W (hereafter U 336 ), 15,000 s in F555W (V 555 ), and 5,500 s in F814W (I 814 ) and were reobserved in I 814 , with exposure times of 5 680 s, (GO-8153) approximately 5 years later. This allowed separation of field stars from the low-luminosity cluster members through proper motion properties (Bedin et al 2001). Finally, there exist shallow (249 s) V 555 and (249 s) I 814 observations (GO-6116) originally obtained to search for the optical counterpart of PSR B1620À26.…”

Section: Optical Observationsmentioning

confidence: 99%

X‐Ray Sources and Their Optical Counterparts in the Globular Cluster M4

Bassa

Pooley

Homer

et al. 2004

ApJ

124

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We report on the Chandra X-Ray Observatory ACIS-S3 imaging observation of the Galactic globular cluster M4 (NGC 6121). We detect 12 X-ray sources inside the core and 19 more within the cluster half-mass radius. The limiting luminosity of this observation is L X % 10 29 ergs s À1 for sources associated with the cluster, the deepest X-ray observation of a globular cluster to date. We identify six X-ray sources with known objects and use ROSAT observations to show that the brightest X-ray source is variable. Archival data from the Hubble Space Telescope allow us to identify optical counterparts to 16 X-ray sources. Based on the X-ray and optical properties of the identifications and the information from the literature, we classify two (possibly three) sources as cataclysmic variables, one X-ray source as a millisecond pulsar, and 12 sources as chromospherically active binaries. Comparison of M4 with 47 Tuc and NGC 6397 suggests a scaling of the number of active binaries in these clusters with the cluster (core) mass.

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“…And Bedin et al (2001) provide a considered description of the comparison between isochrones and observed properties of very low mass stars. The fit is lousy.…”

Section: Stellar Structure and Evolutionmentioning

confidence: 99%

Astrophysics in 2002

Trimble

Aschwanden

2003

PUBL ASTRON SOC PAC

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ABSTRACT. This has been the Year of the Baryon. Some low temperature ones were seen at high redshift, some high temperature ones were seen at low redshift, and some cooling ones were (probably) reheated. Astronomers saw the back of the Sun (which is also made of baryons), a possible solution to the problem of ejection of material by Type II supernovae (in which neutrinos push out baryons), the production of R Coronae Borealis stars (previously-owned baryons), and perhaps found the missing satellite galaxies (whose failing is that they have no baryons). A few questions were left unanswered for next year, and an attempt is made to discuss these as well.

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Color-Magnitude Diagram and Luminosity Function of M4 near the Hydrogen-burning Limit

Cited by 54 publications

References 9 publications

VLT-UVES analysis of two giants in the bulge metal-poor globular cluster HP-1

VLT-UVES analysis of two giants in the bulge metal-poor globular cluster HP-1

X‐Ray Sources and Their Optical Counterparts in the Globular Cluster M4

Astrophysics in 2002

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