Open AccessMirror eclipses in the cataclysmic variable IP Peg
Author(s) -
Littlefair S.P.,
Dhillon V.S.,
Marsh T.R.,
Harlaftis E.T.
Publication year - 2001
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.1365-8711.2001.04744.x
Subject(s) - physics , eclipse , astrophysics , dwarf nova , accretion (finance) , radius , cataclysmic variable star , accretion disc , astronomy , intermediate polar , stars , white dwarf , computer security , computer science
We present time resolved K ‐band infrared spectra of the dwarf nova (DN) IP Peg in early quiescence. The Brackett γ and He i ( λ 2.0581) lines in our data show hitherto unseen behaviour, which we term a mirror eclipse , and interpret as an eclipse of the secondary star by an optically thin accretion disc. Mirror eclipses are a direct probe of the structure and physical conditions of accretion discs. For example, on assuming the relevant level populations to be in local thermal equilibrium, we constrain the temperature and density of the optically thin material, causing the mirror eclipse in IP Peg to be and respectively. In order to match our data, we find that at least the outermost 20 per cent of the disc (in radius) must be entirely optically thin. Implications for time‐dependent disc models are examined.