A supersoft variable low-luminosity X-ray source in the globular cluster M3

Hertz, P.; Grindlay, J.; Bailyn, Charles D.

doi:10.1086/186886

Cited by 19 publications

(20 citation statements)

References 4 publications

(5 reference statements)

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“…4. Thanks to the use of more accurate HRI positions, these accuracies are better than those achieved before by Hertz et al (1993) and Geffert (1998). The positions listed in Table 2 are those of the Fig.…”

Section: Ngc 5272/mmentioning

confidence: 76%

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A census with ROSAT of low-luminosity X-ray sources in globular clusters

Verbunt¹

2001

A&A

113

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Abstract. I analyze 101 observations from the ROSAT archive to search for X-ray sources in or near 55 globular clusters. New sources are found in the cores of NGC 362 (a double source), NGC 6121 (marginally significant), NGC 6139, and NGC 6266; and outside the cores of NGC 6205, NGC 6352 and NGC 6388. More accurate positions are determined for the X-ray sources in some ten clusters. The improved position for the source in NGC 6341 excludes the suggested ultraviolet counterpart. It is shown that one of the two sources reported near the core NGC 6626 is spurious, as is the detection of a pulsar period in the PSPC data of this cluster; the central source is resolved in three sources. One source reported previously in NGC 6304 is demoted to an upper limit. For 20 cluster cores better upper limits to the X-ray luminosity are obtained.From a statistical analysis I argue that several sources outside the cluster cores may well belong to the clusters. All spectral energy distributions observed so far are relatively soft, with bremsstrahlung temperatures 0.9 keV; there is evidence however that bremsstrahlung spectra do not correctly describe the spectra. The X-ray luminosity per unit mass for the cluster as a whole does not depend on the concentration; the luminosity per unit mass for the core may increase with the cluster concentration.

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Section: Ngc 5272/mmentioning

confidence: 76%

“…The positions of the 1992 observation are compatible with these. The source numbering is as in Hertz et al (1993), except for Source G, which is a new source, not identical to source D listed by Hertz et al (1993).…”

Section: Ngc 5272/mmentioning

confidence: 99%

A census with ROSAT of low-luminosity X-ray sources in globular clusters

Verbunt¹

2001

A&A

113

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“…This sort of scenario has not been considered for neutron stars in GCs, because the required mass of the donor star is larger than the mass of stars at the turnoff of typical Galactic GCs (Di Stefano & Davies 1996 have considered such a scenario for white dwarfs; see Hertz, Grindlay, & Bailyn 1993;Verbunt et al 1994Verbunt et al , 1995. There are two sets of circumstances, however, that alone or in combination can provide a pool of massive donor stars.…”

Section: Viability In a Globular Cluster Environmentmentioning

confidence: 99%

Bright X‐Ray Sources in M31 Globular Clusters

Stefano

Kong

Garcia

et al. 2002

ApJ

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We have conducted Chandra observations of $2560 arcmin 2 ($131 kpc 2 ) of M31 and find that the most luminous X-ray sources in most of our fields are in globular clusters. Of the 28 globular cluster X-ray sources in our fields, 15 are newly discovered. Approximately one-third of all the sources have L X ([0.5-7] keV Þ > 10 37 ergs s À1 , and approximately one-tenth of all the sources have L X ([0.5-7] keV) close to or above 10 38 ergs s À1 . The most luminous source, in the globular cluster Bo 375, is consistently observed to have L X greater than 2 Â 10 38 ergs s À1 . (1) We present data on the spectra and/or light curves of the five most luminous M31 globular cluster sources. (2) We explore possible explanations for the high X-ray luminosities of the brightest sources. These include that the X-ray sources may be composites, the radiation we receive may be beamed, metallicity effects could be at work, or the sources may be accreting black holes. We weigh each of these possibilities against the data. In addition, we introduce a neutron star model in which mass transfer proceeds on the thermal timescale of the donor star. Our model can produce luminosities of several times 10 38 ergs s À1 and leads to a set of well-defined predictions. (3) We compute the X-ray luminosity function and the distribution of counts in wavebands that span the range of energies to which Chandra is sensitive. We find the peak X-ray luminosity is higher and that systems with L X > 10 37 ergs s À1 constitute a larger fraction of all GC sources than in our Galaxy. (4) We study the possible reasons for this difference between M31 and Galactic globular cluster X-ray sources and identify three promising explanations.

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“…These authors as well as Carney (1976) quote magnitudes compatible with that seen by Meinunger (1972). Additional X-ray observations from ROSAT are reported by Hertz et al (1993), where the source is termed RX J134211+2828.7. The published B max = 18.3 implies M B = −22.0, again a typical value.…”

Section: S 10764 = B2 1339+28 = 1e 13399+2844mentioning

confidence: 99%

The Meinunger “Nicht Rote” Objects

Margon

Deutsch

1999

PUBL ASTRON SOC PAC

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ABSTRACT. Four high-latitude slow variable stars have been noted by Meinunger as "nicht rote" ("not red") objects and thus curious. We have previously reported that one of these objects, CC Boo, is in fact a QSO. Here we present observations demonstrating that the remaining three are also highly variable active galactic nuclei. The most interesting object of the four is perhaps S10765 (ϭNGP9 F324Ϫ0276706), which proves to be a resolved galaxy at . Despite the rapid and large reported variability amplitude ( mag), the z ϭ 0.063Dm ∼ 1.6 spectrum is that of a perfectly normal galaxy, with no emission lines or evident nonthermal continuum. We also present new spectroscopic and photometric observations for AR CVn, suggested by Meinunger to be an RR Lyrae star despite its very faint magnitude ( ). The object is indeed one of the most distant RR Lyrae ABS ϭ 19.4 stars known, at a galactocentric distance of ∼40 kpc.

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A supersoft variable low-luminosity X-ray source in the globular cluster M3

Cited by 19 publications

References 4 publications

A census with ROSAT of low-luminosity X-ray sources in globular clusters

A census with ROSAT of low-luminosity X-ray sources in globular clusters

Bright X‐Ray Sources in M31 Globular Clusters

The Meinunger “Nicht Rote” Objects

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