Searching for White Dwarf Exoplanets: WD Case Study 1

Bruce Gary, Arizona 14-inch T.G. Tan, Australia 12-inch Ivan Curtis, Australia 11-inch Paul Tristram, New Zealand 24-inch Akihiko Fukui, Japan ( ” ) 2

Background PAWM (Pro-Am White dwarf Monitoring), amateurs, 46 WDs, no exoplanet transits However, 3 WDs were variable (surprise) WD was the most interesting WDs are small (same size as Earth) Hot Jupiters are much bigger, & can orbit close Therefore, big planets can reflect WD light and produce variations 3

Example Light Curve 4

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Starspot can explain observed variation 7

But so can an orbiting exoplanet Planet radius = 1.23 x Jupiter Orbit distance = a.u. (for P = 2.7 hrs) Orbit inclination close to edge-on Slightly too close for “habitable zone” 8

Follow-Up Observations Needed Radial velocity (to see if hypothetical exoplanet is on far side when brightest) Spectroscopy to check idea of 1) Lyman-alpha emission is coming from planet atmosphere & 2) convection bringing He to surface (e.g., never-before seen spot) All of above require professional hardware 9

Conclusions Discovering exoplanets around WDs is within reach of amateurs! But professional collaboration (follow-up) will be needed. 10