FROM X-RAY DIPS TO ECLIPSE: WITNESSING DISK REFORMATION IN THE RECURRENT NOVA U Sco

Ness, J. U.; Schaefer, Bradley E.; Dobrotka, A.; Sądowski, Aleksander; Drake, J. J.; Barnard, R.; Talavera, A.; González‐Riestra, R.; Page, K. L.; Hernanz, M.; Sala, G.; Starrfield, S.

doi:10.1088/0004-637x/745/1/43

Cited by 53 publications

(99 citation statements)

References 39 publications

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“…U Sco is another well observed Galactic recurrent nova with a subgiant companion. Ness et al (2012) examined an Xray eclipse during the 2010 outburst in detail and concluded that the mass accretion resumed as early as day 22.9, midway during the SSS phase. In a binary with a subgiant companion, thus, we can expect the mass accretion to resume just after an outburst.…”

Section: Absorption By Surrounding Neutral Hydrogenmentioning

confidence: 99%

X-RAY FLASHES IN RECURRENT NOVAE: M31N 2008-12a AND THE IMPLICATIONS OF THE SWIFT NONDETECTION

Kato

Saio

Henze

et al. 2016

ApJ

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Models of nova outbursts suggest that an X-ray flash should occur just after hydrogen ignition. However, this X-ray flash has never been observationally confirmed. We present four theoretical light curves of the X-ray flash for two very massive white dwarfs (WDs) of 1.380 and 1.385 M ⊙ and for two recurrence periods of 0.5 and 1 years. The duration of the X-ray flash is shorter for a more massive WD and for a longer recurrence period. The shortest duration of 14 hours (0.6 days) among the four cases is obtained for the 1.385 M ⊙ WD with one year recurrence period. In general, a nova explosion is relatively weak for a very short recurrence period, which results in a rather slow evolution toward the optical peak. This slow timescale and the predictability of very short recurrence period novae give us a chance to observe X-ray flashes of recurrent novae. In this context, we report the first attempt, using the Swift observatory, to detect an X-ray flash of the recurrent nova M31N 2008-12a (0.5 or 1 year recurrence period), which resulted in the non-detection of X-ray emission during the period of 8 days before the optical detection. We discuss the impact of these observations on nova outburst theory. The X-ray flash is one of the last frontiers of nova studies and its detection is essentially important to understand the pre-optical-maximum phase. We encourage further observations.

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Section: Absorption By Surrounding Neutral Hydrogenmentioning

confidence: 99%

X-RAY FLASHES IN RECURRENT NOVAE: M31N 2008-12a AND THE IMPLICATIONS OF THE SWIFT NONDETECTION

Kato

Saio

Henze

et al. 2016

ApJ

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“…Drake et al 2008) and nova V2491 Cyg (starting its SSS state 36 d after the optical outburst, see e.g. Ness et al 2008) demonstrated that each Galactic nova seems to have its own peculiarities.…”

Section: Introductionmentioning

confidence: 98%

X‐ray emission from optical novae in M 31

Pietsch

2010

Astron Nachr

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The first supersoft source (SSS) identification with an optical nova in M 31 was based on ROSAT observations. Twenty additional X-ray counterparts (mostly identified as SSS by their hardness ratios) were detected using archival ROSAT, XMM-Newton and Chandra observations obtained before July 2002. Based on these results optical novae seem to constitute the major class of SSS in M 31. An analysis of archival Chandra HRC-I and ACIS-I observations obtained from July 2004 to February 2005 demonstrated that M 31 nova SSS states lasted from months to about 10 years. Several novae showed short X-ray outbursts starting within 50 d after the optical outburst and lasting only two to three months. The fraction of novae detected in soft X-rays within a year after the optical outburst was more than 30 %. Ongoing optical nova monitoring programs, optical spectral follow-up and an up-to-date nova catalogue are essential for the X-ray work. Re-analysis of archival nova data to improve positions and find additional nova candidates are urgently needed for secure recurrent nova identifications. Dedicated XMM-Newton/Chandra monitoring programs for X-ray emission from optical novae covering the centre area of M 31 continue to provide interesting new results (e.g. coherent 1105 s pulsations in the SSS counterpart of nova M31N 2007-12b). The SSS light curves of novae allow us -together with optical informationto estimate the mass of the white dwarf, of the ejecta and the burned mass in the outburst. Observations of the central area of M 31 allow us -in contrast to observations in the Galaxy -to monitor many novae simultaneously and proved to be prone to find many interesting SSS and nova types.

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“…The U Sco 2010 outburst had an extensive follow-up both from space and ground, and from X-ray to near-infrared (NIR) wavelengths Munari et al 2010;Schaefer et al 2011;Banerjee et al 2010;Yamanaka et al 2010;Diaz et al 2010;Kafka & Williams 2010;Manousakis et al 2010;Ness et al 2012;Orio et al 2010;Osborne et al 2010). …”

Section: Introductionmentioning

confidence: 99%

U Scorpii 2010 outburst: a new understanding of the binary accretion disk and the secondary star

Mason¹,

Ederoclite²,

Williams³

et al. 2012

A&A

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We present optical and near-infrared (NIR) spectroscopic observations of U Sco 2010 outburst. From the analysis of lines profiles we identify a broad and a narrow component and show that the latter originates from the reforming accretion disk. We show that the accretion resumes shortly after the outburst, on day +8, roughly when the super-soft (SSS) X-ray phase starts. Consequently U Sco SSS phase is fueled (in part or fully) by accretion and should not be used to estimate m rem , the mass of accreted material which has not been ejected during the outburst. In addition, most of the He emission lines, and the He ii lies in particular, form in the accretion flow/disk within the binary and are optically thick, thus preventing an accurate abundance determination.A late spectrum taken in quiescence and during eclipse shows Ca ii H&K, the G-band and Mg ib absorption from the secondary star.However, no other significant secondary star features have been observed at longer wavelengths and in the NIR band.

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FROM X-RAY DIPS TO ECLIPSE: WITNESSING DISK REFORMATION IN THE RECURRENT NOVA U Sco

Cited by 53 publications

References 39 publications

X-RAY FLASHES IN RECURRENT NOVAE: M31N 2008-12a AND THE IMPLICATIONS OF THE SWIFT NONDETECTION

X-RAY FLASHES IN RECURRENT NOVAE: M31N 2008-12a AND THE IMPLICATIONS OF THE SWIFT NONDETECTION

X‐ray emission from optical novae in M 31

U Scorpii 2010 outburst: a new understanding of the binary accretion disk and the secondary star

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