arXiv subjects

Marina Orio

Publications and source records attributed to Marina Orio.

39 records · Page 3Linked to original sources

arXiv2003

A XMM-Newton observation of Nova LMC 1995, a bright supersoft X-ray source

Nova LMC 1995, previously detected during 1995-1998 with ROSAT, was observed again as a luminous supersoft X-ray source with XMM-Newton in December of 2000. This nova offers the possibility to observe the spectrum of a hot white dwarf, burning hydrogen in a shell and not obscured by a wind or by nebular emission like in other supersoft X-ray sources. Notwithstanding uncertainties in the calibration of the EPIC instruments at E<0.5 keV, using atmospheric models in Local Thermonuclear Equilibrium we derived T(eff)=400,000-450,000 K, L(bol)=2.3 x 110(-14) 0(37) erg cm(-2) s(-1) and we verified that the C abundance is not significantly enhanced. The RGS spectra do not show emission lines of a wind or nebula, but the white dwarf absorption lines cannot be resolved. The upper limit to the flux in the 0.6-10 keV range is 10(-14) erg cm(-2) s(-1). There is no rapid or large variability in the light curve, but we find a peak at 5.25 hours in the power spectrum.

astro-ph↗

arXiv2001

V382 Vel: a "shocking" supersoft x-ray source?

Nova Vel 1999 (V382 Vel) was observed with BeppoSAX twice, 15 days and 6 months after the optical maximum. A hard X-ray source was detected in the first observation, while the second time also a very luminous supersoft X-ray source was detected. The continuum observed in the supersoft range with the BeppoSAX LECS cannot be fitted with atmospheric models of hot hydrogen burning while dwarfs. We suggest that we are observing instead mainly a ``pseudocontinuum'', namely a blend of very strong emission lines in the supersoft X-ray range.

astro-ph↗

arXiv1998

Regularities in the Long Term Optical Light Curve of the Black Hole Candidate Binary A0620-00 (V616 Mon)

We have monitored the R and I magnitudes of the black hole candidate system A0620-00 (V616 Mon) in the years 1991-95 at the Wise Observatory. Combining our data with some additional measurements, we analyze a sparsely covered 7 years light curve of the star. We find that the average R-band magnitude is varying on a time scale of a few hundreds days, with a peak to peak amplitude of 0.3 mag. The two maxima in the well known double hump binary cycle, as well as one of the minima between them, vary by a few percent relative to one another in a seemingly random way. One maximum is on the average higher than the other by 0.05 mag. The depth of the second minimum is varying with significantly higher amplitude, in clear correlation with the long term variability of the mean magnitude of the system. It is shallower than the other minimum at times of maximum light, and it becomes deeper at times of minimum system light. According to the commonly acceptable phasing of the binary cycle, the systematically varying minimum corresponds to inferior conjunction of the red dwarf in the system. We cannot suggest any simple geometrical model for explaining the regularities that we find in the long term photometric behaviour of the star.

astro-ph↗