can stellar activity make a planet seem...
TRANSCRIPT
Can stellar activity make a planet seem misaligned?
Mahmoud OshaghInstitute for Astrophysics,
University of Göttingen, Germany
Collaborators: N. Santos, M. Gillon, S. Dreizler, A. Reiners, A. Triaud, A. Burdanov, P. FiguieraX. Bonfils, S. Udry
Outline
Stellar activity and photometric transit
Stellar activity and spectroscopic transit
Non-occulted stellar spots
Barros et al. 2014
CoRoT-7b
20% overestimation
Occulted stellar spotsHAT-P-11b observed by Kepler
Some people consider assigning a zero weight to the anomalous points of the light curve (e.g Sanchis-Ojeda & Winn 2011)
Transit timing measurementsJupiter size planet transiting a solar-like star overlaps a spot with a filling factor of 1 %, produces the maximum value of TTV around 200 seconds.
Oshagh et al ,2013b
SOAP-T
Best fit
Planet radius estimationsA radius of Neptune size planet transiting a solar-like star and overlapping a spot with filling factor of 1 %, can be underestimated by 4%.
Oshagh+2013b
SOAP-T
Best fit
Impact of stellar activity on spectroscopic transit
Rossiter–McLaughlin effect
RM and unocculted spots
Boldt & Oshagh et al, in prep
SOAP-T simulations
RM and occulted spots
RM and occulted spots
A Neptune-sized aligned planet transitsa solar like star with vsini=3 km/s
The inaccurate estimation on the spin-orbit angle due to stellar activity can be quite significant (up to 30 degrees).
We found that aligned transiting planets are the ones that can be easily misinterpreted as misaligned owing to the stellar activity.
Oshagh+2016
SOAP-T simulations
RM and occulted spots
WASP-16b, 2010 March, May 2011 (Brown et al 2012)
WASP-16b, 2010 Jul (Albrecht et al 2012)
20 degree -4 degree
Occulted spot could be a possible explanation for conflicting results on spin-orbit angle estimations, e.g, HAT-P-7:
E. Jehin/ESO Y. Beletsky (LCO)/ESO
Simultaneous HARPS and TRAPPISTWe obtained 6 nights on HARPS to perform consecutive RM observations of 6 planets (with simultaneous transit observation with TRAPPIST)
TRAPPIST HARPS
WASP-41b
Technical issue Too windy for TRAPPIST
WASP-19b
Improving our RM modeling
Cegla et al. 2016
1.Convective center-to-limb variations2.Inhibition of convective blueshift in active regions
Thanks for your attention!
Transit timing measurements200 seconds amplitude of TTV can be induced by an Earth-mass planet in a mean-
motion resonance with a transiting Jupiter-like planet on a 3 day orbit.
Mazeh+2013
SOAP-T SOAP-T produces the expected light curve and the radial velocity signal of a system
consisting of a rotating spotted star with a transiting planet. SOAP-T is able to reproduce the “positive bump” anomaly in the transit light curve and RV due to a planet-spot overlap (Oshagh et al, A&A, 2013a.).
Oshagh et al, A&A, 2013a.
Transit timing variation (TTV)
Boue+2012
Rossiter–McLaughlin effect
–McLaughlin effect