ISSN:
1572-946X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The evolutionary status of hydrogen-poor stars is analyzed. Photoelectric observations of six objects are reported as a first step of a long-term project devoted to search for variability of a large sample of hydrogen-poor stars. The observed stars show phenomena of microvariability with an amplitude of the order of 0m. 1 or less. Two extreme helium stars have been examined: a period in the range of 0d.162-0d.164 has been found for BD+ 1002179, andP=0d.1079962 for BD+1303324. The mass-losing O subdwarf (sdO) BD+370 443 presents short-term fluctuations with a time-scale of several minutes and long-term variations on a scale of months. The ‘standard’ sdO BD+750325 is probably non-variable, although light variations of very small amplitude (Δm≃0.03) with a time-scale of about 1 hr might be present. The high gravity sdO BD+2504655, which is very close to the white dwarf stage, also presents variability on a time-scale of about 13 minutes, and might be an analog of the recently discovered pulsating sdO, or ‘hot’ white dwarf, PG 1159-035. The variability of the intermediate helium star HD 37776 is finally confirmed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00648561
Permalink