EDP Sciences
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Volume 376, Number 3, September IV 2001
Page(s) 978 - 981
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011017

A&A 376, 978-981 (2001)
DOI: 10.1051/0004-6361:20011017

Research Note
Th4-4: A Be star which has turned into a planetary nebula within 30 years

L. N. Kondratyeva

Fesenkov Astrophysical Institute, Kazakhstan, Isaak Newton Institute of Chile, Kazakhstan Branch, 480020 Almaty Observatory, Kazakhstan

(Received 8 January 2001 / 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 $V=14\fm 4$ to $16\fm 6$, 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: planetary nebulae: general: early type stars -- stars: emission lines, Be stars: individual: Th4 -- 4 -- stars: evolution

Offprint request: L. N. Kondratyeva, Kon@afi.south-capital.kz

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