TY - JOUR
T1 - Remarkable spectral variability on the spin period of the accreting
T2 - White dwarf in V455 And
AU - Bloemen, Steven
AU - Steeghs, D.
AU - De Smedt, Kenneth
AU - Vos, Yvonne J
AU - Gänsicke, B. T.
AU - Marsh, Thomas R.
AU - Rodriguez-Gil, Pablo
PY - 2013/3/11
Y1 - 2013/3/11
N2 - We present spin-resolved spectroscopy of the accreting white dwarf binary V455 And.With a suggested spin period of only 67 s, it has one of the fastest spinning white dwarfs known. To study the spectral variability on the spin period of the white dwarf, we observed V455 And with 2 s integration times, which is significantly shorter than the spin rate of the white dwarf. To achieve this cadence, we used the blue arm of the ISIS spectrograph at the 4.2-m William Herschel Telescope, equipped with an electron multiplying CCD (EMCCD). Strong coherent signals were detected in our time series, which led to a robust determination of the spin period of the white dwarf (Pspin=67.619 ± 0.002 s). Folding the spectra on the white dwarf spin period uncovered very complex emission line variations in Hγ, HeI λ4472 and He II λ4686. We attribute the observed spin phase dependence of the emission line shape to the presence of magnetically controlled accretion on to the white dwarf via accretion curtains, consistent with an intermediate polar type system. We are, however, not aware of any specific model that can quantitatively explain the complex velocity variations we detect in our observations. The orbital variations in the spectral lines indicate that the accretion disc of V455 And is rather structureless, contrary to the disc of the prototype of the intermediate polars, DQ Her. This work demonstrates the potential of EMCCDs to observe faint targets at high cadence, as readout noise would make such a study impossible with conventional CCDs.
AB - We present spin-resolved spectroscopy of the accreting white dwarf binary V455 And.With a suggested spin period of only 67 s, it has one of the fastest spinning white dwarfs known. To study the spectral variability on the spin period of the white dwarf, we observed V455 And with 2 s integration times, which is significantly shorter than the spin rate of the white dwarf. To achieve this cadence, we used the blue arm of the ISIS spectrograph at the 4.2-m William Herschel Telescope, equipped with an electron multiplying CCD (EMCCD). Strong coherent signals were detected in our time series, which led to a robust determination of the spin period of the white dwarf (Pspin=67.619 ± 0.002 s). Folding the spectra on the white dwarf spin period uncovered very complex emission line variations in Hγ, HeI λ4472 and He II λ4686. We attribute the observed spin phase dependence of the emission line shape to the presence of magnetically controlled accretion on to the white dwarf via accretion curtains, consistent with an intermediate polar type system. We are, however, not aware of any specific model that can quantitatively explain the complex velocity variations we detect in our observations. The orbital variations in the spectral lines indicate that the accretion disc of V455 And is rather structureless, contrary to the disc of the prototype of the intermediate polars, DQ Her. This work demonstrates the potential of EMCCDs to observe faint targets at high cadence, as readout noise would make such a study impossible with conventional CCDs.
KW - Cataclysmic variables-white dwarfs
KW - Novae
KW - Stars: individual: V455 And
UR - http://www.scopus.com/inward/record.url?scp=84874137122&partnerID=8YFLogxK
U2 - 10.1093/mnras/sts622
DO - 10.1093/mnras/sts622
M3 - Article
AN - SCOPUS:84874137122
VL - 429
SP - 3433
EP - 3438
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -