Open AccessMulti‐epoch spectroscopy of IY UMa: quiescence, rise, normal outburst and superoutburst
Author(s) -
Rolfe Daniel J.,
Haswell Carole A.,
Abbott Timothy M. C.,
MoralesRueda Luisa,
Marsh T. R.,
Holdaway G.
Publication year - 2005
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 - 10.1111/j.1365-2966.2005.08639.x
Subject(s) - physics , astrophysics , light curve , accretion (finance) , astronomy , accretion disc , observable , emission spectrum , line (geometry) , photometry (optics) , flux (metallurgy) , doppler effect , spectral line , stars , geometry , mathematics , materials science , quantum mechanics , metallurgy
We exploit rare observations covering the time before and during a normal outburst in the deeply eclipsing SU UMa system IY UMa to study the dramatic changes in the accretion flow and emission at the onset of outburst. Through Doppler tomography we study the emission distribution, revealing classic accretion flow behaviour in quiescence, with the stream–disc impact ionizing the nearby accretion disc. We observe a delay of hours to a couple of days between the rise in continuum and the rise in the emission lines at the onset of the outburst. From line profiles and Doppler maps during normal and superoutburst, we conclude that reprocessing of boundary layer (BL) radiation is the dominant emission line mechanism in outburst and that the normal outburst began in the outer disc. The stream–disc impact feature (the orbital hump) in the Hα line flux light curve disappears before the onset of the normal outburst and may be an observable signal heralding an impending outburst.