X‐Ray Spectroscopy of the 2006 Outburst of RS Ophiuchi

Nelson, Thomas; Orio, Marina; Cassinelli, J. P.; Still, M.; Leibowitz, E. M.; Mucciarelli, P.

doi:10.1086/524054

Cited by 85 publications

(172 citation statements)

References 33 publications

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“…The best-fit models use a blackbody temperature (T BB ) of 5.8 × 10 5 K and 5.5 × 10 5 K and a luminosity of 6.3 × 10 38 ergs s −1 and 8.0 × 10 38 ergs s −1 , respectively, on D31 and D49. This is in agreement with the WD temperature of around 8 × 10 5 K derived from x-ray studies by Nelson et al (2008). The low χ 2 red values of 1.2 and 1.8 for the two dates, respectively, indicate that the fits are satisfactory.…”

Section: Resultssupporting

confidence: 89%

Abundance analysis of the recurrent nova RS Ophiuchi (2006 outburst)

Das

Mondal

2015

New Astronomy

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We present an analysis of elemental abundances of ejecta of the recurrent nova RS Oph using published optical and near-infrared spectra during the 2006 outburst. We use the CLOUDY photoionization code to generate synthetic spectra by varying several parameters, the model generated spectra are then matched with the observed emission line spectra obtained at two epochs. We obtain the best fit model parameters through the χ 2 minimization technique. Our model results fit well with observed optical and near-infrared spectra. The best-fit model parameters are compatible with a hot white dwarf source with T BB of 5.5 -5.8 × 10 5 K and roughly constant a luminosity of 6 -8 × 10 36 ergs s −1 . From the analysis we find the following abundances (by number) of elements with respect to solar: He/H = 1.8 ± 0.1, N/H = 12.0 ± 1.0, O/H = 1.0 ± 0.4, Ne/H = 1.5 ± 0.1, Si/H = 0.4 ± 0.1, Fe/H = 3.2 ± 0.2, Ar/H = 5.1 ± 0.1, and Al/H = 1.0 ± 0.1, all other elements were set at the solar abundance. This shows the ejecta are significantly enhanced, relative to solar, in helium, nitrogen, neon, iron and argon. Using the obtained parameter values, we estimate an ejected mass in the range of 3.4 -4.9 × 10 −6 M ⊙ which is consistent with observational results.

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Section: Resultssupporting

confidence: 89%

Abundance analysis of the recurrent nova RS Ophiuchi (2006 outburst)

Das

Mondal

2015

New Astronomy

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“…Two recurrent novae with massive WDs of unknown composition were observed using gratings while they were relatively hard X-ray sources. RS Oph did not show very strong lines of Mg and Al, (Nelson et al 2008;Ness et al 2009), consistently with the ultraviolet spectra of a previous outburst (Contini et al 1995). V745 Sco was observed as a hard X-ray source with NuSTAR (Orio et al 2015) and shortly later it was observed it with the Chandra HETG.…”

Section: V959 Mon a Nova Discovered As A Gamma-ray Sourcesupporting

confidence: 85%

Chemical and Physical Parameters From X-Ray High-Resolution Spectra of the Galactic Nova V959 Mon

Peretz

Orio

Behar

et al. 2016

ApJ

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Two observations of V959 Mon, done using the Chandra X-ray gratings during the late outburst phases (2012 September and December), offer extraordinary insight into the physics and chemistry of this Galactic ONe nova. The X-ray flux was 1.7 × 10 −11 erg cm −2 s −1 and 8.6 × 10 −12 erg cm −2 s −1 , respectively at the two epochs. The first result, coupled with electron density diagnostics and compared with published optical and ultraviolet observations, indicates that most likely in 2012 September the X-rays originated from a very small fraction of the ejecta, concentrated in very dense clumps. We obtained a fairly good fit to the September spectrum with a model of plasma in collisional ionization equilibrium (CIE) with two components; one at a temperature of 0.78 keV, associated with flat-topped and asymmetrical emission lines, blueshifted by 710-930 km s −1 ; the other at a temperature of 4.5 keV, mostly contributing to the high-energy continuum. However, we cannot rule out a range of plasma temperatures between these two extremes; we also modeled the spectrum as a static cooling flow, but the available models and the data quality are not adequate yet to differentiate between the two-component fit and a smoothly varying temperature structure. In December, the central white dwarf (WD) became visible in X-rays. We estimate an effective temperature of 680,000 K, consistent with a WD mass ≥1.1 M . The WD flux is modulated with the orbital period, indicating high inclination, and two quasi-periodic modulations with hour timescales were also observed. No hot plasma component with temperature above 0.5 keV was observed in December, and the blueshifted component cooled to kT 0.45 keV. Additionally, new emission lines due to a much cooler plasma appeared, which were not observed two months earlier. We estimate abundances and yields of elements in the nova wind that cannot be measured in the optical spectra and confirm the high Ne abundance previously derived for this nova. We also find high abundance of Al, 230 times the solar value, consistently with the prediction that ONe novae contribute to at least 1/3rd of the Galactic yield of 26 Al.

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“…The XMM-Newton observation taken on day 26.1 is also dominated by the early shock emission, but has an additional soft component that appeared during the observation. Nelson et al (2008) reported that a 35 s period was present during a short time when the soft count rate rapidly increased by a factor 3, and in Fig. 1.…”

Section: Rs Ophmentioning

confidence: 84%

“…So far, no convincing identifications were found after investigating possibilities of extreme line shifts (Nelson et al 2008) or exotic elemental abundances (Orio et al 2010).…”

Section: Rs Ophmentioning

confidence: 99%

Short-period X-ray oscillations in super-soft novae and persistent super-soft sources

Ness

Beardmore

Osborne

et al. 2015

A&A

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Context. Transient short-period (<100 s) oscillations have been found in the X-ray light curves of three novae during their super-soft source (SSS) phase and in one persistent SSS. Aims. We pursue an observational approach to determine possible driving mechanisms and relations to fundamental system parameters such as the white dwarf mass. Methods. We performed a systematic search for short-period oscillations in all available XMM-Newton and Chandra X-ray light curves of persistent SSS and novae during their SSS phase. To study time evolution, we divided each light curve into short timesegments and computed power spectra. We then constructed a dynamic power spectrum from which we identified transient periodic signals even when only present for a short time. We base our confidence levels on simulations of false-alarm probability for the chosen oversampling rate of 16, corrected for multiple testing based on the number of time segments. From all time segments of each system, we computed fractions of time when periodic signals were detected. Results. In addition to the previously known systems with short-period oscillations, RS Oph (35 s), KT Eri (35 s), V339 Del (54 s), and Cal 83 (67 s), we found one additional system, LMC 2009a (33 s), and also confirm the 35 s period from Chandra data of KT Eri. The oscillation amplitudes are of about <15% of the respective count rates and vary without any clear dependence on the X-ray count rate. The fractions of the time when the respective periods were detected at 2σ significance (duty cycle) are 11.3%, 38.8%, 16.9%, 49.2%, and 18.7% for LMC 2009a, RS Oph, KT Eri, V339 Del, and Cal 83, respectively. The respective highest duty cycles found in a single observation are 38.1%, 74.5%, 61.4%, 67.8%, and 61.8%. Conclusions. Since fast rotation periods of the white dwarfs as origin of these transient oscillations are speculative, we concentrate on pulsation mechanisms. We present initial considerations predicting the oscillation period to scale linearly with the white dwarf radius (and thus mass), weakly with the pressure at the base, and luminosity. Estimates of the size of the white dwarf could be useful for determining whether these systems are more massive than typical white dwarfs, and thus whether they are growing from accretion over time. Signs of such mass growth may have implications for whether some of these systems are attractive as Type Ia supernova progenitors.

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X‐Ray Spectroscopy of the 2006 Outburst of RS Ophiuchi

Cited by 85 publications

References 33 publications

Abundance analysis of the recurrent nova RS Ophiuchi (2006 outburst)

Abundance analysis of the recurrent nova RS Ophiuchi (2006 outburst)

Chemical and Physical Parameters From X-Ray High-Resolution Spectra of the Galactic Nova V959 Mon

Short-period X-ray oscillations in super-soft novae and persistent super-soft sources

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