2006CBET..718....1M

U. Munari, A. Siviero, L. Tomasella, and M. Valentini, Istituto Nazionale di Astrofisica, Astronomical Observatory of Padova, write that a series of echelle spectra (range 380-730 nm, resolving power 20000) have been secured of the new bright variable star in Cas (cf. CBETs 711, 712) with the Asiago 1.82-m telescope on Nov. 1.85, 2.73, and 3.71 UT. The spectra are characterized by a hot continuum with Balmer and Mg II 448.1-nm absorption lines whose heliocentric radial velocities on the three nights are -36, -34, and -34 (± 1) km/s, respectively. The broad wings of the Balmer lines indicate a surface gravity similar to that of main sequence dwarfs. No helium lines are visible, and Balmer absorption lines do not present an emission core. The absorption line cores are sharp enough to exclude a fast rotation. The strong insterstellar Na I D doublet is visible at heliocentric radial velocity -14 (± 1) km/s. The mean 0.049-nm equivalent width of the Na I D2 589.0-nm line corresponds to a reddening E(B-V) = 0.29, following calibration via Munari and Zwitter (1997, A.Ap. 318, 269). The object's brightness has been noted to decrease markedly from one night to the next. In comparison with the spectra from Nov. 1.85, the Balmer and Mg II 448.1-nm aborption lines have increased their equivalent widths by 30 percent on Nov. 2.73 and by 55 percent on Nov. 3.71. On the Nov. 3.71 spectrum, H_beta reaches a 1.25-nm equivalent width, which is appropriate for an early A-type main-sequence star. Inspection of the stellar seeing disk (2".2) on the TV screen of the telescope guiding system does not reveal the presence of a close bright companion.