83,527 research outputs found
Physical Properties of the Transiting Planetary System TrES-3
We present four new transits of the planetary system TrES-3 observed between
2009 May and 2010 June. Among these, the third transit by itself indicates
possible evidence for brightness disturbance, which might be the result of the
planet blocking a cool starspot on the stellar surface. A total of 109 transit
times, including our measurements, were used to determine the improved
ephemeris with a transit epoch of 2454185.9109440.000072 HJED and an
orbital period of 1.306187000.00000015 d. We analyzed the transit light
curves using the JKTEBOP code and adopting the quadratic limb-darkening law. In
order to derive the physical properties of the TrES-3 system, the transit
parameters are combined with the empirical relations from eclipsing binary
stars and stellar evolutionary models. The stellar mass and radius obtained
from a calibration using , log and [Fe/H] are consistent
with those from the isochrone analysis. We found that the exoplanet TrES-3b has
a mass of 1.930.07 M, a radius of 1.300.04 R,
a surface gravity of log =3.450.02, a density of 0.820.06
, and an equilibrium temperature of 164123 K. The results
are in good agreement with theoretical models for gas giant planets.Comment: 15 pages, including 4 figures and 4 tables, accepted for publication
in PAS
Finite sample properties of multiple imputation estimators
Finite sample properties of multiple imputation estimators under the linear
regression model are studied. The exact bias of the multiple imputation
variance estimator is presented. A method of reducing the bias is presented and
simulation is used to make comparisons. We also show that the suggested method
can be used for a general class of linear estimators
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