Open AccessInvestigating the structure of the accretion disc in WZ Sge from multiwaveband time‐resolved spectroscopic observations – I
Author(s) -
Skidmore Warren,
Mason Elena,
Howell Steve B.,
Ciardi David R.,
Littlefair Stuart,
Dhillon V. S.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03781.x
Subject(s) - physics , astrophysics , dwarf nova , accretion (finance) , accretion disc , spectral line , intermediate polar , radius , doppler effect , astronomy , line (geometry) , emission spectrum , white dwarf , stars , geometry , mathematics , computer security , computer science
We present the first of two papers describing an in‐depth study of multiwaveband phase‐resolved spectroscopy of the unusual dwarf nova WZ Sge. In this paper we present an extensive set of Doppler maps of WZ Sge covering optical and infrared emission lines, and describe a new technique for studying the accretion discs of cataclysmic variables using ratioed Doppler maps. Applying the ratioed Doppler map technique to our WZ Sge data shows that the radial temperature profile of the disc is unlike that predicted for a steady state α disc. Time‐averaged spectra of the accretion disc line flux (with the bright spot contribution removed) show evidence in the shapes of the line profiles for the presence of shear broadening in a quiescent non‐turbulent accretion disc. From the positions of the bright spots in the Doppler maps of different lines, we conclude that the bright spot region is elongated along the ballistic stream, and that the density of the outer disc is low. The velocity of the outer edge of the accretion disc measured from the H α line is found to be 723±23 km s −1 . Assuming that the accretion disc reaches to the 3:1 tidal resonance radius, we derive a value for the primary star mass of 0.82 M ⊙ . We discuss the implications of our results on the present theories of WZ Sge type dwarf nova outbursts.