GD 99 - an unusual, rarely observed DAV white dwarf

TL;DR

This paper reports new observations of the white dwarf GD 99, confirming its unusual pulsation patterns with both long and short periods, and suggests a possible binary nature as an explanation.

Contribution

It provides the first detailed analysis of GD 99's pulsation behavior and proposes a binary interpretation for its unique mode grouping.

Findings

Confirmed unusual pulsation behavior with mixed periods

Identified regular spacing in mode groups

Suggested binary nature as a possible explanation

Abstract

New observations of GD 99 are analysed. The unusual pulsation behaviour, showing both long and short periods, has been confirmed. All the available periods show a grouping of short and long period modes with roughly regular spacing. If we interpret the groups separately, a binary nature can be a possible explanation as in the similar cases of WD 2350-0054 and G29-38.