Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2011-08-12
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
Scientific paper
We present an analysis of X-ray and UV data obtained with the XMM-Newton Observatory of the long period dwarf nova RU Peg. RU Peg contains a massive white dwarf, possibly the hottest white dwarf in a dwarf nova, it has a low inclination, thus optimally exposing its X-ray emitting boundary layer, and has an excellent trigonometric parallax distance. We modeled the X-ray data using XSPEC assuming a multi-temperature plasma emission model built from the MEKAL code. We obtained a maximum temperature of 31.7 keV, based on the EPIC MOS1, 2 and pn data, indicating that RU Peg has an X-ray spectrum harder than most dwarf novae, except U Gem. This result is consistent with and indirectly confirms the large mass of the white dwarf in RU Peg. The X-ray luminosity we computed corresponds to a boundary layer luminosity for a mass accretion rate of 2.E-11 Msun/yr (assuming Mwd=1.3Msun), in agreement with an expected quiescent accretion rate. The modeling of the O VIII emission line at 19A as observed by the RGS implies a projected stellar rotational velocity of 695 km/s, i.e. the line is emitted from material rotating at about 936-1245 km/s (for i about 34-48deg) or about 1/6 of the Keplerian speed; this velocity is much larger than the rotation speed of the white dwarf inferred from the FUSE spectrum. Cross-correlation analysis yielded an undelayed component and a delayed component of 116 +/- 17 sec where the X-ray variations/fluctuations lagged the UV variations. This indicates that the UV fluctuations in the inner disk are propagated into the X-ray emitting region in about 116 sec. The undelayed component may be related to irradiation effects.
Balman Soelen
Barrett Paul Everett
Godon Patrice
Ness Jan-Use
Schlegel Eric
No associations
LandOfFree
XMM-Newton observations of the dwarf nova RU Peg in quiescence: Probe of the boundary layer does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with XMM-Newton observations of the dwarf nova RU Peg in quiescence: Probe of the boundary layer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and XMM-Newton observations of the dwarf nova RU Peg in quiescence: Probe of the boundary layer will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-16720