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Spectroscopic identification of the high-amplitude variable star in Leo

ATEL # 951; A. Rau, E.O. Ofek (both Caltech Optical Observatories), M. Lacy & G. Wilson (both IPAC, Caltech)
on 23 Nov 2006; 1:53 UT
Password Certification: Eran Ofek (eran@wise.tau.ac.il)

Subjects: Optical, Transients, Variables

We report on follow-up spectroscopy of the high-amplitude variable star in Leo (see Christensen et al., CBET#746) with the COSMIC spectrograph mounted on the Hale-5m telescope at Palomar Observatory. Observations were performed on UT 2006 November 21.55 and covered a wavelength range from 4000 to 8200 Angstrom with a resolution of ~8 Angstrom.

The spectrum shows a very blue continuum and prominent Balmer absorption lines (H_epsilon to H_alpha) together with a weak HeI P-Cygni profile around 5876 Angstrom. The best fitting stellar template is a B3-4V star.

We note that the observered high amplitude (7 magnitudes in the g-band) is not expected for B-stars. Furthermore, the photometric colors of the quiescent SDSS counterpart (u-g=0.09, g-r=0.11, r-i=-0.21, i-z=0.39) are incompatible with the colors of main sequence stars or giants of any type.

We further inspected images taken using the Near-Earth Asteroid Tracking (NEAT) project during 1998 (Jan, Feb), 2002 (Feb, Mar, Apr, May) and 2005 (May). No previous outburst of this source is detected.


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