International Symposium on Planetary Science (IAPS2013) Venue: 3 rd floor of Astronomical Building Shanghai Astronomical Observatory, Chinese Academy of Sciences
The follow-up observations of several exoplanet transit events Liyun Zhang & Qingfeng Pi GuiZhou University
Outline Background Photometric Observations Light curve analysis Transit timing variation analysis Our future plan
Background Figure.1 The movie of transit of extra-solar planet http://kepler.nasa.gov/
Background The transit of extroplanet can provide information: Transit time, and duration, its relative radii and orbital inclination Mass and density Formation and evolution Collier Cameron et al., 2007; et c
Background The study of Transit timing Variation (Diaz et al., 2008; Sozzetti et al., 2009; ) : Reveal the effect of other perturbing planets in the exoplanetary systems (Steffen & Agol 2005) Moons of the transiting exoplanet (Szabo et al. 2006; Simon et al., 2007; Kipping et al., 2009ab.)
Our objects Targets: SuperWASP project: WASP-4b, WASP-36b HATNet project: HAT-P-10b/WASP-11b, HAT-P- 19b, HAT-P-20b, HAT-P-25b CoRoT project: XO project: Kepler HD 198733B; Qatar-2b------- Barge et al. 2008., Pollacco et al., 2006; Christian et al. 2006; Borucke et al. 2010
Observation Telescope: 85cm telescope+1kx1k CCD at Xinglong station of NAOC. Band:R filter Time:2012-- Zhou et al., 2010
Deta Mag The light curves 0.05 R band HAT-P-19b 0.10 0.15 0.20 0.25 0.30 HAT-P-19b-comparisonal star Check star - comparisonal star 20 21 22 23 24 25 26 Time (UT) Figure The light curves of serveral extrasolar event. The black represent the different magnitude of our objects and the comparisonal star. The red one represent the different magnitudeof the comparisonal and check star.
Deta Mag Deta Mag Deta Mag Deta Mag The light curves 0.05 0.10 HAT-P-19b 0.6 WASP 36 0.15 0.7 0.20 0.8 0.25 0.30 20 21 22 23 24 25 26 Time (UT) 0.9 0.00 27 28 29 30 Time (UT) HAT-P-20b HAT-P-25b -0.6 0.05 0.10-0.5 0.15-0.4 26.0 26.5 27.0 27.5 28.0 28.5 29.0 Time (UT) 0.20 HAT-P-25-comparisonal star Check star - comparisonal star 0.25 19 20 21 22 23 24 25 Time (UT) The light curves of serveral extrasolar event. The black represent the different magnitude of our objects and the comparisonal star. The red one represent the different magnitudeof the comparisonal and check star. (2013 in preparing)
Light curve analysis Our transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law (Southworth 2008, 2009) The minimum times and their uncertainties were also determined with the JKTEBOP code and the model parameters.
HAT-P-19b HAT-P-19b: K1 dwarf star GSC 2283-00589 with period = 4.008778 +/- 0.000006days, a mass of 0.84+/- 0.04 M sun, radius of 0.82+/- 0.05 R sun, (Hartman et al., 2011).
Del Mag The light curve analysis 0.10 HAT-P-19b 0.12 0.14 0.16 Observation Model 56270.05 56270.10 56270.15 56270.20 BJD (2400000+) Figure. The light curves of the observed transits (points) and fitted models (red lines) of the exoplanet systems of HAT-P-19b.
Transit parameters of HAT-P-19b Our result Hartman2011 Our Transit minima (BJD) 2456270.1160+/-0.0003 Our Transit depth: 0.0251 +/- 0.0006 mag Our Transit width: 162.3 +/- 2 minute 170 +/- 2 minute Orbital inclination i(deg): 89.836 +/- 4.59 88.2 +/- 0.4 ra+rb: 0.087 +/- 0.003 K(=rb/rA): 0.141 +/- 0.002 0.142+/-0.002 Rms of residuals (mmag) : 3.029 Reduced chi-dquared form errorbars :4.80 Table.1 Transit and orbital parameters of HAT-P-19b
HAT-P-10b HAT-P-10b/WASP11b: The host star is an early to mid K dwarf, with a spectral analysis yielding mass 0.77 +0.1/-0.08 Msun, stellar radius 0.74 +0.04/ 0.03 R sun, an effective temperature of 4800+/- 100K (Bakos et al., 2009; West et al., 2009)
Del Mag The light curve analysis -0.80 HAT-P-10b -0.78-0.76-0.74 Observation Model 56270.95 56271.00 56271.05 56271.10 BJD (2400000+) Figure The light curves of the observed transits and fitted models of the exoplanet systemsof HAT-P-10b.
Transit parameters of HAT-P-10b Our West2009 Bakos 2009 Our Transit minima (BJD): 2456271.01479+/-0.00009 Our Transit depth: 0.0229 +/- 0.0004 mag Our Transit width: 146.9 +/- 1 minute 153 157 +/- 1minute Orbital inclination i(deg): 89.931 +/- 8.52 89.8 88.6 +/- 0.45 ra+rb: 0.088 +/- 0.002 K(=rb/rA): 0.130+/- 0.002 0.127 0.132 +/- 0.001 Rms of residuals: (mmag) 3.733 Reduced chi-squared from errorbars: 11.712 Table.1 Transit and orbital parameters of HAT-P-19b
Transit timing variation analysis We also collected the minima times from Exoplanet Transit database (Poddany et al., 2010) and AXA (Amateur exoplanet Archieve). The ETD time timings were transformed from HJD based on UTC into TDB-based BJD using the online applets2 developed by Eastman et al (2010).
(O-C) The O-C diagram The Orbital ephemeris (BJD) of HAT-P-19b: 2455091.5354 +/- 0.0002+ 4.0087788 +/-0.000001 0.010 HAT-P-19b 0.005 0.000-0.005-0.010 ETD Our observation Polynomial fit 0 50 100 150 200 250 300 Epoch Figure O-C diagrams of the exoplanet systems HAT-P-19b.
(O-C) The O-C diagram The Orbital ephemeris (BJD) of HAT-P-10b: 2454729.9071 +/- 0.0002+ 3.7224810 +/-0.0000009 0.015 HAT-P-10b 0.010 0.005 0.000-0.005-0.010 ETD Our observation Polynomial fit -0.015-50 0 50 100 150 200 250 300 350 400 450 Epoch Figure O-C diagrams of the exoplanet systems HAT-P-19b.
Conlusion 1. Some orbital parameters of the systems are obtained, which agree to the previous results (West et al. 2009; Bakos et a. 2009; Hellier et al. 2011; etc). 2. The timing residuals giving a hint about a period change? which might be due to the presence of a second planet in the system or the sporadic asymmetries of transit curves due to starspots on stellar surface used by magnetic activity (Steffen & Agol 2005; Lee et al. 2012; etc).
Future plan Monitor the exoplanet transit events using 85 cm and 60 cm telescope at Xinglong station, NAOC. Magnetic interaction between an extrasolar planet and its parent star using high-resolution spectra. ------------------ Zhou et al., 2009; Shkolnik et al., 2008)
Thanks
Kepler 11 system
Holman et al., 2004 Variation of transit period
HAT-P-19b Hartman J. D., Bakos G. A., Sato B., et al., 2011, Apj, 726, 52
West et al., 2009 WASP11b
HAT-P-10b HAT-P-10b: 0.487+/-0.018 Mjupiter 1.005+0.032-0.027transiting extrasolar planets GSC 02340-0174 with period P=3.7224747 +/-0.0000065 days, transit epoch 2454759.68683+/-0.00016 and duration 0.109+/- 0.0008days Bakos G. A., Pal A., Torres G., et al., 2009, APJ, 696, 1950
Bakos et al., 2009 HAT-P-10b
Transit of Extra-solar Planet (Photometry)
WASP 43b A hot Jupiter transiting a K7V star every 0.81 d. At 0.6 M sun the host star has the lowest mass of any star (15.6 days rotation period). The planet has a mass of 1.8 Jupiter. (Hellier et al., 2011)
Del Mag The light curve analysis 1.14 1.16 WASP43 1.18 1.20 1.22 observation Model 1.24 0.35 0.36 0.37 0.38 0.39 0.40 0.41 0.42 0.43 0.44 0.45 Epoch The light curves of the observed transits and fitted models of the exoplanet systems. WASP43
(O-C) WASP 43b O-C 0.015 WASP 43 0.010 0.005 0.000-0.005-0.010-0.015 ETC Our observation Polynomial fit 0 200 400 600 800 1000 1200 Epoch 2455528.8685 +/- 0.0001+ 0.81347438 +/- 0.0000002
Transit parameters of WASP 43b ra+rb? K(=rb/rA)? Orbital inclination i(deg)? Our Transit minima (BJD) 2456250.4201 +/- 0.0007 Our Transit depth=0.026 +/- 0.003 mag Our Transit width= 69.5a Rms of residuals (mmag) Reduced chi-squared from errorbars Epoch: 4.008778 +/- 0.000001 The Orbital ephemer (BJD) is 2455528.8685 +/- 0.0001+ 0.81347438 +/-0.0000002 Stellar mass=0.77 +0.01-0.007 M_sun Stellar radius=0.81 +0.01-0.006R_sun Orbital inclination=89.976 + -0.241-0.749 deg Planet radius=1.02 +0.01-0.009R_jup