Research Note Th4-4: A Be star which has turned into a planetary nebula within 30 years
Fesenkov Astrophysical Institute, Kazakhstan, Isaak Newton Institute of Chile, Kazakhstan Branch, 480020 Almaty Observatory, Kazakhstan
Corresponding author: L. N. Kondratyeva, Kon@afi.south-capital.kz
Accepted: 20 June 2001
The first optical spectra of Th4-4, obtained by the author in 1970, showed strong continuum and broad HI emission lines. In other words, at this time the object looked like a Be star. Some years later, [OIII] emission lines appeared in the spectrum indicating the existence of a gaseous envelope. Today the optical spectrum of Th4-4 is quite similar to that of a moderate excitation planetary nebula. The magnitude of the object has dropped from to , and the effective temperature of the central star has increased from 22 000 K up to 40 000 K within the last 30 years.
Key words: ISM: planetary nebulae: general / stars: early type / stars: emission-line, Be / stars: individual: Th4-4 / stars: evolution
© ESO, 2001