Query : 1999A&A...347L..43K

1999A&A...347L..43K - Astronomy and Astrophysics, volume 347, L43-46 (1999/7-3)

Luminous supersoft X-ray emission from the recurrent nova U Scorpii.


Abstract (from CDS):

BeppoSAX detected luminous 0.2-2.0 keV supersoft X-ray emission from the recurrent nova U Sco ∼19-20 days after the peak of the optical outburst in February 1999. U Sco is the first recurrent nova to be observed during a luminous supersoft X-ray phase. Non-LTE white dwarf atmosphere spectral models (together with a ∼0.5 keV optically thin thermal component) were fitted to the BeppoSAX spectrum. We find that the fit is acceptable assuming enriched He and an enhanced N/C ratio. This implies that the CNO cycle was active during the outburst, in agreement with a thermonuclear runaway scenario. The best-fit temperature is ∼ 9x105 K and the bolometric luminosity (0.16-1.2)x1036erg/s.(d/kpc)2. These values are in agreement with those predicted for steady nuclear burning on a WD close to the Chandrasekhar mass. The fact that U Sco was detected as a supersoft X-ray source is consistent with steady nuclear burning continuing for at least one month after the outburst. This means that only a fraction of the previously accreted H and He was ejected during the outburst and that the WD can grow in mass, ultimately reaching the Chandrasekhar limit. This makes U Sco a candidate type Ia supernova progenitor.

Abstract Copyright:

Journal keyword(s): stars: binaries: close - X-rays: stars - stars: evolution - stars: white dwarfs - stars: individual: U Scorpii

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 V* U Sco CV* 16 22 30.7791646104 -17 52 43.166822628           F8+K2 495 0
2 V* V1974 Cyg No* 20 30 31.6546001712 +52 37 50.837478240           ~ 558 0

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