The observation of exoplanet transit events in China
Xiao-bin Wang1, Sheng-hong Gu1, Andrew Collier Cameron2, Xiang-song Fang1, Dong-tao Cao1 and Zhi-liang Guo1
1.Yunnan Observatory, CAS, China2.University of St. Andrews, UK
Shanghai 2009.07.21
Outline
Background Observation Data reduction Light curve analysis Future plan
Background
It is known well that the transit of exoplanet can provide information about its radii and orbital inclination which can be used to derive its mass and density, furthermore, to infer the clue on its formation and evolution.
The monitoring for changes on orbital inclination, transit time and duration makes it possible to detect other low-mass exoplanets.
Here, we give out the preliminary results of our follow-up observation on transit events and future plan on this topic in China.
Observation Instruments
1.0m telescope+2Kx2K CCD at Yunnan Observatory
R filter
85cm telescope+1Kx1K CCD at Xinglong station of NAOC.
R filter
Targets: SuperWASP project: WASP-1b, WASP-2b, WAS
P-11b… XO project: XO-2b, XO-3b… HATNet project: HAT-P-1b, HAT-P-9b… CoRoT project: CoRoT-Exo-1b…
Data reduction
Photometry Aperture photometry (uncrowded field)
IRAF package Image subtraction (crowded field)
ISIS package (Alard & Lupton 1998, Alard 2000)
Two examples
Remove the systematic errors for aperture photometry results Coarse decorrelation (Collier Cameron et al. 200
6) SysRem algorithm (Tamuz et al. 2005)
WASP-11b
XO-2b
Light curve analysis
Markov Chain Monte Carlo code (Collier Cameron et al. 2007)
Result 1: WASP-11b
Transit epoch=2454793.18411+0.00018-0.00018
Transit depth=0.0217+0.0002-0.0003mag
Transit width=0.09579+0.00072-0.00342days
Stellar mass=0.77+0.01-0.007M_sun
Stellar radius=0.81+0.01-0.006R_sun
Orbital inclination=89.976+ -0.241 -0.749 degPlanet radius=1.02+0.01
-0.009R_jup
Result 2: XO-2b
Transit epoch=2454804.32478+0.00021-0.00027
Transit depth=0.0132+0.0006 - -0.0001 mag
Transit width=0.09853+ -0.00266 -0.01995 days Stellar mass=0.968+0.014 -0.008 M_sun Stellar radius=0.975+0.011
-0.006R_sun Orbital inclination=88.982+ -0.443 -1.616 deg Planet radius=0.955+0.028 - -0.002 R_jup
Future plan New instruments
Lijiang 2.4m telescope CCD camera: 2Kx2K chip, FOV 4’x4’ YFOSC CCD camera: 4Kx4K chip, FOV 9’X9’ Mosaic CCD camera: 6Kx6K, 4chips, FOV 9’x9’ LiJET: LiJiang Exoplanet Tracker (see Ting-gui Wang’s tal
k yesterday)
Research projects Defocus observation for transit events
Improve the accuracy of transit light curves Open cluster transit survey
Discover new transit exoplanet candidates LiJET follow-up confirmation for the brighter ones of the
m
Thank you!