An Extremely Hot Pulsating Prewhite Dwarf from OGLE

Abstract

We show that the blue 18.3 minutes variable object discovered in the Galactic disk by the OGLE-III survey and named OGLE-GD-WD-0001 is a pulsating prewhite dwarf of PG 1159 spectral type. With an effective temperature of about 160,000 K it is among the hottest known pulsators being located close to the blue edge of the GW Virginis instability strip. The long-term OGLE observations indicate that the object has a positive period change rate of about 5 × 10 ^−10 s s ^−1 and thus already contracts. There are no traces of a planetary nebula around this star.

Keywords

• Sky surveys
• White dwarf stars
• Fundamental parameters of stars
• Pulsating variable stars