A pulsating star inside Eta Carinae I. Light variations 1992-1994 (1995)
Keywords :
techniques photometric - stars: individual: {eta} Car; variables; supergiants; oscillations
Abstract:We present and analyze two seasons of intense photometric monitoring in the Stroemgren uvbyH{beta} system of {eta} Carinae (October 1992-August 1994). The luminous blue variable (LBV) in the core did not show much S Dor activity, i.e. it was in a relatively quiescent stage. This situation was very favourable for studying its optical micro variations. It appears that the central LBV pulsates (presumably in a non-radial mode) like other massive evolved stars, the {alpha} Cyg variables. The quasi-period is 58.56d. The linear ephemeris is: JD_max_=2448875.0 +58.56 E. Support was found for the existence of the presumed periodicity of 52.4d of the so-called "dimples", shallow dips in the light curve which only last for a few days. The cause may be
...(more)
We present and analyze two seasons of intense photometric monitoring
in the Stroemgren uvbyH{beta} system of {eta} Carinae (October
1992-August 1994). The luminous blue variable (LBV) in the core did
not show much S Dor activity, i.e. it was in a relatively quiescent
stage. This situation was very favourable for studying its optical
micro variations. It appears that the central LBV pulsates (presumably
in a non-radial mode) like other massive evolved stars, the {alpha}
Cyg variables. The quasi-period is 58.56d. The linear ephemeris is:
JD_max_=2448875.0 +58.56 E. Support was found for the existence of the
presumed periodicity of 52.4d of the so-called "dimples", shallow dips
in the light curve which only last for a few days. The cause may be
the eclipse of a small companion or of a hot spot in an accretion
disk. The H{beta} index became bluer by ~0.07mag during the last 11/2
years and shows an oscillation in anti-phase with the 58.56d
pulsation, suggesting that the HII region(s) responsible for the
hydrogen line emission has a relatively high luminosity. This is
another reason to suppose that a second luminous source, perhaps a
luminous disk (with a hot spot), may be present in the {eta} Car
system.
Objects concerned:
--------------------------------------------------
RA (2000) DE Name(s)
--------------------------------------------------
10 45 03.6 -59 41 03 eta Car = HR 4210 = HD 93308
--------------------------------------------------
