A
proposed optical fiber connection between VATT and the Potsdam Echelle
Polarimetric and Spectroscopic Instrument (PEPSI) detector at the Large
Binocular Telescope on Mt. Graham has an important exoplanet
implication. NASA’s Kepler spacecraft has produced several thousand
possible transit detections so far, but a true verification can only be
made if a spectroscopic follow-up of a given candidate shows radial
velocity variations in agreement with the period from the light curve
and with an amplitude appropriate for a planetary mass. It is hoped that
the VATT and PEPSI could be operated for many nights during a year and
thus sample an orbital period domain not accessible to any
other facility in the world.
When one observes an exoplanet as it passes its host star, the dip in
the observed brightness of the system is directly correlated to the
atmosphere of the exoplanet. From the shape (depth, width, etc.) of the
eclipse signal, one can determine the molecular abundances and
temperature profile of the planet’s atmosphere. However, many of these
exoplanets orbit about sometimes fairly active stars. When these stars
have spots, it can affect the lightcurve. Gabor and LPL graduate student
Zellem (an alumnus of the Vatican Observatory Summer School, VOSS 2007)
are looking into using VATT to study the photometric brightness of a
few key exoplanetary systems over a long period of time (at least for a
season, initially) to better constrain the starspot sizes.
