X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

Juett, Adrienne M.; Chakrabarty, Deepto

doi:10.1086/379188

Cited by 51 publications

(92 citation statements)

References 48 publications

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“…Neon also shows a gradient but with a large scatter probably due to contribution intrinsic to the sources (see e.g. Juett & Chakrabarty 2003;Madej et al 2010). However, the linear fits show negative gradients for all the abundances which is consistent with the fact that stellar evolution proceeds faster in the Galactic inner regions.…”

Section: Ism Abundancessupporting

confidence: 68%

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Pinto

Kaastra

Costantini

et al. 2013

A&A

125

127

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Context. The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. Aims. We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). Methods. We used high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measured the column densities of O, Ne, Mg, and Fe with an empirical model and estimated the Galactic abundance gradients. Results. The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25% and 65-90% of the total amount of O i and Fe i is found in dust.The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Conclusions. Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.

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Section: Ism Abundancessupporting

confidence: 68%

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Pinto

Kaastra

Costantini

et al. 2013

A&A

125

127

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“…The ratio is 62% higher than solar with a significance of 4σ. High Ne/O ratios have also been measured from other UCXBs employing XMM-Newton and Chandra (Juett & Chakrabarty 2003). However, it was found that the Ne/O ratio tends to change from observation to observation with accompanying changing continuum fluxes.…”

Section: Discussionmentioning

confidence: 90%

An X-ray and optical study of the ultracompact X-ray binary A 1246-58

Zand

Bassa

Jonker

et al. 2008

A&A

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Results are discussed of an X-ray and optical observation campaign of the low-mass X-ray binary A 1246-58 performed with instruments on Satellite per Astronomia X ("BeppoSAX"), the Rossi X-ray Timing Explorer (RXTE), the X-ray Multi-mirror Mission ("XMM-Newton"), the Swift mission, and the Very Large Telescope. Spectra and flux time histories are studied. The most important results are the lack of hydrogen spectral features in the optical spectrum, supporting the proposition that this is an ultracompact X-ray binary (UCXB), the determination of a 4.3 kpc distance from time-resolved spectroscopy of thermonuclear X-ray bursts, and the detection of intermediately long thermonuclear bursts as seen in a number of other UCXBs. There is evidence for a Ne/O abundance ratio in the line of sight that is higher than solar and variable. This may be due to different changes in the ionization degrees of Ne and O, which may be related to the variable irradiating flux. We discuss the spectral variability and the peculiarities of the long-term light curve.

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“…These spectra suggest the donor star to be a C/O white dwarf (Nelemans et al 2003(Nelemans et al , 2006Werner et al 2006). This seems to be at odds (see Juett et al 2001;Juett & Chakrabarty 2003) with the fact that we see bursts in 4U 0614+091, which are usually understood as being due to unstable ignition of He or H. Moreover, 4U 0614+091 is an interesting case among the sources showing superbursts. Superbursts are expected to occur only in systems with accretion rates in excess of about 10% of the Eddington rate, i.e., the rate which yields emission at the Eddington limit (Cumming & Bildsten 2001;Strohmayer & Brown 2002).…”

Section: Introductionmentioning

confidence: 91%

What ignites on the neutron star of 4U 0614+091?

Kuulkers¹,

Zand

Atteia

et al. 2010

A&A

103

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The low-mass X-ray binary 4U 0614+091 is a source of sporadic thermonuclear (type I) X-ray bursts. We find bursts with a wide variety of characteristics in serendipitous wide-field X-ray observations by the WATCH on EURECA, the ASM on RXTE, the WFCs on BeppoSAX, the FREGATE on HETE-2, the IBIS/ISGRI on INTEGRAL, and the BAT on Swift, as well as pointed observations with the PCA and HEXTE on RXTE. Most of the bursts are bright, i.e., they reach a peak flux of about 15 Crab, but a few are weak and only reach a peak flux below a Crab. One of the bursts shows a very strong photospheric radius-expansion phase. This allows us to evaluate the distance to the source, which we estimate to be 3.2 kpc. The burst durations vary generally from about 10 s to 5 min. However, after one of the intermediate-duration bursts, a faint tail is seen to at least about 2.4 h after the start of the burst. One very long burst was observed, which lasted for several hours. This superburst candidate was followed by a normal type-I burst only 19 days later. This is, to our knowledge, the shortest burst-quench time among the superbursters. The observation of a superburst in this system is difficult to reconcile if the system is accreting at about 1% of the Eddington limit. We describe the burst properties in relation to the persistent emission. No strong correlations are apparent, except that the intermediate-duration bursts occurred when 4U 0614+091's persistent emission was lowest and calm, and when bursts were infrequent (on average roughly one every month to 3 months). The average burst rate increased significantly after this period. The maximum average burst recurrence rate is about once every week to 2 weeks. The burst behaviour may be partly understood if there is at least an appreciable amount of helium present in the accreted material from the donor star. If the system is an ultra-compact X-ray binary with a CO white-dwarf donor, as has been suggested, this is unexpected. If the bursts are powered by helium, we find that the energy production per accumulated mass is about 2.5 times less than expected for pure helium matter.

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X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

Cited by 51 publications

References 48 publications

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

An X-ray and optical study of the ultracompact X-ray binary A 1246-58

What ignites on the neutron star of 4U 0614+091?

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