BZ Camelopardalis during its 1999/2000 optical low state

¹ Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
² OAN, Instituto de Astronomía, UNAM, AP 877, 22860 Ensenada, México
³ Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10125 Pino Torinese (TO), Italy
⁴ Dept. of Astronomy, Univ. Wisconsin, 1150 University Ave., Madison, WI 53706, USA
⁵ Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
⁶ Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue., Mexico

Corresponding author: J. Greiner, jgreiner@aip.de

Received: 12 April 2001
Accepted: 16 July 2001

Abstract

We report optical observations of the VY Scl star BZ Cam during its previous optical low state in 1999/2000. We find drastic variations in the line profiles. Narrow-band imaging observations show that its nebula extends farther than previously known and seems to be composed of two components. We determine the [ OIII] line intensity of BZ Cam's nebula to erg/cm²/s. We discover a proper motion of BZ Cam of mas/yr which together with the systemic radial velocity yields a space velocity of 125 km s^-1. We re-interpret the nebula as being photo-ionized by hypothesized transient, luminous, supersoft X-ray emission during optical low states, and shaped by the transverse motion of BZ Cam.