2001MNRAS.322..741F -
Mon. Not. R. Astron. Soc., 322, 741-748 (2001/April-3)
Variability of η Carinae - III.
FEAST M., WHITELOCK P. and MARANG F.
Abstract (from CDS):
Spectra (1951-78) of the central object in η Car, taken by A. D. Thackeray, reveal three previously unrecorded epochs of low excitation. Since 1948, at least, these states have occurred regularly in the 2020-d cycle proposed by Damineli et al. They last about 10per cent of each cycle. Early slit spectra (1899-1919) suggest that at that time the object was always in a low state. JHKL photometry is reported for the period 1994-2000. This shows that the secular increase in brightness found in 1972-94 has continued and its rate has increased at the shorter wavelengths. Modulation of the infrared brightness in a period near 2020d continues. There is a dip in the JHKL light curves near 1998.0, coincident with a dip in the X-ray light curve. Evidence is given that this dip in the infrared repeats in the 2020-d cycle. As suggested by Whitelock & Laney, the dip is best interpreted as an eclipse phenomenon in an interacting binary system; the object eclipsed being a bright region (`hotspot'), possibly on a circumstellar disc or produced by interacting stellar winds. The eclipse coincides in phase and duration with the state of low excitation. It is presumably caused by a plasma column and/or by one of the stars in the system.
Abstract Copyright:
The Royal Astronomical Society
Journal keyword(s):
stars: individual: η Car
Simbad objects:
1
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