ARCSAT ID NUMBER: AS04

DESCRIPTIVE TITLE: Search for Short-Period Planets Orbiting Bright White Dwarfs

PI: Brett Morris (UW)

OBSERVER(S): Brett Morris (UW), Ada Beale & Doug Branton (University of 
Washington's Pre-MAP)

UNCERTIFIED/UNTRAINED OBSERVERS:

COLLABORATORS: Ada Beale & Doug Branton (UW/Pre-MAP)
 
CONTACT INFORMATION: bmmorris@uw.edu, 631-860-5116

TIME REQUESTED: 
1-2 weeks total. We have unobserved WD targets available at all RAs, so all 
months are good.

INSTRUMENT: FlareCam

FILTERS: g

COMMENTS: We will be taking continuous time series photometry for many
consecutive hours -- anything that can be done to check that the telescope 
tracking is as reliable as possible would be appreciated. Dark time would be
strongly preferred since many of our white dwarf targets are V > 15.

BRIEF SCIENCE JUSTIFICATION: 

The Kepler Mission has shown that Sun-like stars host planets in abundance
(Petigura et al. 2013) but little theoretical work has been done to describe 
what happens to planets when their Sun-like host stars leave the main sequence 
(Agol 2011). Spectroscopy of white dwarf atmospheres has revealed 
metal pollution indicative of active accretion of rocky material (Gansicke et
al. 2012), though the source of the debris - perhaps a disk of asteroids or tidally
disrupted planets - is unknown. If a planet orbits a typical WD near the tidal 
disruption radius, its orbital period falls near 8-10 hours; if this planet 
transits, a serendipitous observer could potentially observe two transits of the 
planet in one night of continuous observations. In addition, since typical white
dwarfs are roughly Earth-sized, the transit of an Earth-sized planet can cause
changes in brightness on the order of several tens of percent for durations on
the order of one minute (Agol 2011). 

We propose a one or two-week run of short cadence, high S/N, time-series photometry 
of bright white dwarfs that we will use to to search for planets orbiting the 
brightest white dwarfs available from APO, in addition to searching for planets 
around white dwarfs known to be metal polluted with ARCSAT. We have identified
several metal polluted white dwarfs (typically dim with V~15-16) and a few 
exceptionally bright white dwarfs (V<13) that will be visible from APO in 
this quarter. We have discussed collaborating to implement a new guiding 
procedure to improve tracking for long observations with ARCSAT with with Joe 
Huehnerhoff, and we can use data collected in this run as a practice set for 
the experimental tracking and guidance correction algorithm. These data will be
analyzed as part of a Pre-MAP (Pre-Major in Astronomy Program) project for two 
undergraduates at the UW. 

REFERENCES
Agol, E. 2011, ApJL, 731, L31 
Gansicke, B.T., Koester, D., Farihi, J., et al. 2012, MNRAS, 424, 333 
Petigura, E.A., Howard, A.W., & Marcy, G.W. 2013, PNAS, 110, 19273