Year: 2001
Type: article
Abstract: 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.
Source: Astronomy and Astrophysics
Author: L. N. Kondratyeva
Institution: Fesenkov Astrophysical Institute
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2139734495