Sub-Saturn planet MOA-2008-BLG-310Lb: Likely to be in the Galactic bulge
Loading...
Date
2009-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
The Ohio State University
Abstract
We report the detection of sub-Saturn-mass planet MOA-2008-BLG-310Lb and
argue that it is the most likely candidate yet for a bulge planet. Deviations
from the single-lens fit are smoothed out by finite-source effects and so are not
immediately apparent from the light curve. Nevertheless, we find that a lens
model in which the primary has a planetary companion is favored by delta chi-squared of 880. Detailed analysis yields a planet/star mass ratio q = (3.3 ± 0.3) × 10−4 and
an angular separation between the planet and star within 10% of the angular
Einstein radius. Using color-magnitude data from the source, we are able to
constrain the distance to the lens DL to be DL > 6.0 kpc if it is a star (ML >
0.08M⊙). This is the only host discovered so far that must be in the bulge if it is
a star. Analysis of the blended light associated with the event (most likely from
the lens but possibly a companion to the lens or source) allows us to estimate
the mass of the lens, ML = 0.69 ± 0.14M⊙. Within 10 years the lens will be
separated from the source by ∼ 54mas. Thus the source of the excess light will
likely be detectable by direct observation. At that time, it will be possible to
determine unambiguously whether the lens and its planet are in the bulge. Advisor: Richard Pogge
Description
Keywords
gravitational microlensing, planet discoveries, exoplanets, galactic bulge