Bibcode
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
Bibliographical reference
The Astrophysical Journal, Volume 775, Issue 1, article id. 66, 10 pp. (2013).
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9
2013
Journal
Citations
19
Refereed citations
15
Description
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.