SIMBAD references

2004ApJ...609..755B - Astrophys. J., 609, 755-765 (2004/July-2)

X-ray sources and their optical counterparts in the globular cluster M4.

BASSA C., POOLEY D., HOMER L., VERBUNT F., GAENSLER B.M., LEWIN W.H.G., ANDERSON S.F., MARGON B., KASPI V.M. and VAN DER KLIS M.

Abstract (from CDS):

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 LX~1029 ergs/s 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.

Abstract Copyright:

Journal keyword(s): Stars: Binaries: Close - Galaxy: Globular Clusters: General - Galaxy: Globular Clusters: Individual: Messier Number: M4 - Galaxy: Globular Clusters: Individual: NGC Number: NGC 6121 - Stars: Novae, Cataclysmic Variables - X-Rays: Stars

Nomenclature: Table 1: [BPH2004] CX NN (Nos 1-31).

Errata: Addendum vol. 619, p. 1189 (2005)

CDS comments: Table 1 : CX 9w is a misprint for CX 9

Simbad objects: 45

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2022.10.03-17:32:23

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