Detection of an ultraviolet and visible counterpart of the NGC 6624 X-ray burster

King, Ivan R.; Stanford, S. A.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Disney, M. J.; Deharveng, J. M.; Jakobsen, P.; Kamperman, T. M.; Macchetto, F.; Mackay, C. D.; Paresce, Francesco; Weigelt, G.; Baxter, Daniel; Greenfield, P.; Jędrzejewski, R.; Nota, A.; Sparks, W. B.; Sosin, C.

doi:10.1086/186973

Cited by 40 publications

(43 citation statements)

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“…The B ¼ 18:7 UV/optical counterpart detected by King et al (1993) was later confirmed by the detection of periodic variations at P orb ¼ 685 s ( King & Watson 1986;Stella et al 1987; see also Anderson et al 1997). The NS is thus in an ultracompact binary with an evolved, H-poor companion, and one of the shortest orbital periods known.…”

Section: A39 3a 1820à303 (=Sgr X-4) In Ngc 6624mentioning

confidence: 74%

Thermonuclear (Type I) X‐Ray Bursts Observed by theRossi X‐Ray Timing Explorer

Galloway

Muno

Hartman

et al. 2008

Astrophysical Journal Supplement Series, The

684

1,183

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We have assembled a sample of 1187 thermonuclear (type I) X-ray bursts from observations of 48 accreting neutron stars by the Rossi X-ray Timing Explorer, spanning more than 10 years. The sample contains examples of two of the three theoretical ignition regimes (confirmed via comparisons with numerical models) and likely examples of the third. We present a detailed analysis of the variation of the burst profiles, energetics, recurrence times, presence of photospheric radius expansion, and presence of burst oscillations, as a function of accretion rate. We estimated the distance for 35 sources exhibiting radius-expansion bursts, and found that the peak flux of such bursts varies typically by 13%. We classified sources into two main groups based on the burst properties: (1) both long and short bursts (indicating mixed H/ He accretion), and (2) consistently short bursts (primarily He accretion), and we calculated the mean burst rate as a function of accretion rate for the two groups. The decrease in burst rate observed at >0:06Ṁ Edd (k2 ; 10 37 ergs s À1) is associated with a transition in the persistent spectral state and (as has been suggested previously) may be related to the increasing role of steady He burning. We found many examples of bursts with recurrence times <30 minutes, including burst triplets and even quadruplets. We describe the oscillation amplitudes for 13 of the 16 burst oscillation sources, as well as the stages and properties of the bursts in which the oscillations are detected. The burst properties are correlated with the burst oscillation frequency; sources spinning at <400 Hz generally have consistently short bursts, while the more rapidly spinning systems have both long and short bursts. This correlation suggests either that shear-mediated mixing dominates the burst properties, or alternatively that the nature of the mass donor (and hence the evolutionary history) has an influence on the long-term spin evolution.

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Section: A39 3a 1820à303 (=Sgr X-4) In Ngc 6624mentioning

confidence: 74%

Thermonuclear (Type I) X‐Ray Bursts Observed by theRossi X‐Ray Timing Explorer

Galloway

Muno

Hartman

et al. 2008

Astrophysical Journal Supplement Series, The

684

1,183

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“…The error bar shows the magnitude variation due to the different aperture size (20% variation of aperture radius In the plot of color against [Fe/H], M31 and (NUV Ϫ V ) 0 Galactic GC data appear to follow the trend indicated by the isochrones, a general correlation between color and (NUV Ϫ V ) 0 metallicity. On the other hand, comparison of the (FUV Ϫ color with the models suggests the promise of gleaning age V ) 0 information (Yi 2003), provided that other sources of significant UV flux in Figure 4 (e.g., extreme HB and PAGB stars, and low-mass X-ray binaries; King et al 1993) can be quantified. In the color versus [Fe/H] diagram, M31 and Ga-(FUV Ϫ V ) 0 lactic GCs are well located in the age range ‫2ע(‬ Gyr) of model predictions and show no significantly different age distribution between the two GC systems, suggesting that the M31 and Galactic GC systems share a similar mean age and age spread, at least, for the oldest GCs.…”

Section: Resultsmentioning

confidence: 99%

Galaxy Evolution Explorer Ultraviolet Photometry of Globular Clusters in M31

Rey¹,

Rich²,

Lee³

et al. 2005

ApJ

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We present ultraviolet photometry for globular clusters (GCs) in M31 from 15 deg 2 of imaging using the Galaxy Evolution Explorer (GALEX). We detect 200 and 94 GCs with certainty in the near-ultraviolet (NUV; 1750-2750 ) and far-ultraviolet (FUV; 1350-1750 ) bandpasses, respectively. Our rate of detection is aboutÅ A 50% in the NUV and 23% in the FUV, to an approximate limiting V magnitude of 19. Out of six clusters with seen in the NUV, none is detected in the FUV bandpass. Furthermore, we find no candidate metal-[Fe/H] 1 Ϫ1 rich clusters with significant FUV flux because of the contribution of blue horizontal-branch (HB) stars, such as NGC 6388 and NGC 6441, which are metal-rich Galactic GCs with hot HB stars. We show that our GALEX photometry follows the general color trends established in previous UV studies of GCs in M31 and the Galaxy. Comparing our data with Galactic GCs in the UV and with population synthesis models, we suggest that the age ranges of M31 and Galactic halo GCs are similar.

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“…Van der Klis et al (1993a) show that an apparent negative period derivative can be the result of acceleration of the binary in the cluster potential. According to measurements with the HST the projected position of the binary is very close to the cluster centre, which makes a significant contribution of gravitational acceleration to the observed period derivative more likely (King et al 1993).…”

Section: Discussionmentioning

confidence: 99%

Reduced magnetic braking and the magnetic capture model for the formation of ultra-compact binaries

Sluys

Verbunt

Pols

2005

A&A

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Abstract.A binary in which a slightly evolved star starts mass transfer to a neutron star can evolve towards ultra-short orbital periods under the influence of magnetic braking. This is called magnetic capture. In a previous paper we showed that ultrashort periods are only reached for an extremely small range of initial binary parameters, in particular orbital period and donor mass. Our conclusion was based on one specific choice for the law of magnetic braking, and for the loss of mass and angular momentum during mass transfer. In this paper we show that for less efficient magnetic braking it is impossible to evolve to ultra-short periods, independent of the amount of mass and associated angular momentum lost from the binary.

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Detection of an ultraviolet and visible counterpart of the NGC 6624 X-ray burster

Cited by 40 publications

References 0 publications

Thermonuclear (Type I) X‐Ray Bursts Observed by theRossi X‐Ray Timing Explorer

Thermonuclear (Type I) X‐Ray Bursts Observed by theRossi X‐Ray Timing Explorer

Galaxy Evolution Explorer Ultraviolet Photometry of Globular Clusters in M31

Reduced magnetic braking and the magnetic capture model for the formation of ultra-compact binaries

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