Hubble Space Telescope and Ground-based Observations of V455 Andromedae Post-outburst

Szkody, Paula; Mukadam, Anjum S.; Gänsicke, Boris T.; Henden, Arne; Sion, Edward M.; Townsley, Dean M.; Christian, Damian; Falcon, Ross E.; Pyrzas, Stylianos; Brown, Justin; Funkhouser, Kelsey
Referencia bibliográfica

The Astrophysical Journal, Volume 775, Issue 1, article id. 66, 10 pp. (2013).

Fecha de publicación:
9
2013
Número de autores
11
Número de autores del IAC
0
Número de citas
19
Número de citas referidas
15
Descripción
Hubble Space Telescope spectra obtained in 2010 and 2011, 3 and 4 yr after the large amplitude dwarf nova outburst of V455 And, were combined with optical photometry and spectra to study the cooling of the white dwarf, its spin, and possible pulsation periods after the outburst. The modeling of the ultraviolet (UV) spectra shows that the white dwarf temperature remains ~600 K hotter than its quiescent value at 3 yr post-outburst, and still a few hundred degrees hotter at 4 yr post-outburst. The white dwarf spin at 67.6 s and its second harmonic at 33.8 s are visible in the optical within a month of outburst and are obvious in the later UV observations in the shortest wavelength continuum and the UV emission lines, indicating an origin in high-temperature regions near the accretion curtains. The UV light curves folded on the spin period show a double-humped modulation consistent with two-pole accretion. The optical photometry 2 yr after outburst shows a group of frequencies present at shorter periods (250-263 s) than the periods ascribed to pulsation at quiescence, and these gradually shift toward the quiescent frequencies (300-360 s) as time progresses past outburst. The most surprising result is that the frequencies near this period in the UV data are only prominent in the emission lines, not the UV continuum, implying an origin away from the white dwarf photosphere. Thus, the connection of this group of periods with non-radial pulsations of the white dwarf remains elusive. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., (AURA) under NASA contract NAS 5-26555, with the Apache Point Observatory (APO) 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium (ARC), and the McDonald Observatory 2.1 m telescope which is owned and operated by the University of Texas at Austin.