An Extremely Hot Pulsating Pre-White Dwarf from OGLE

TL;DR

This paper reports the discovery of OGLE-GD-WD-0001, an extremely hot pulsating pre-white dwarf with a 18.3-minute period, providing insights into its pulsation behavior and evolutionary status near the blue edge of the GW Virginis instability strip.

Contribution

It identifies and characterizes one of the hottest known pulsating pre-white dwarfs, expanding understanding of stellar pulsation at very high temperatures.

Findings

Discovered a 18.3-minute pulsation period in OGLE-GD-WD-0001.

Measured a positive period change rate indicating contraction.

Located near the blue edge of the GW Virginis instability strip.

Abstract

We show that the blue 18.3-minute variable object discovered in the Galactic disk by the OGLE-III survey and named OGLE-GD-WD-0001 is a pulsating pre-white 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 $5 \times 10^{-10}$ $s~s^{-1}$ and thus already contracts. There are no traces of a planetary nebula around this star.