K2 - 19, THE FIRST K2 MULTI-PLANETARY SYSTEM SHOWING TTVS Susana C.C. Barros Instituto de Astrofísica e Ciências do Espaço, Porto, Portugal Collaborators: Almenara, J.M.; Demangeon, O.; Tsantaki, M.; Santerne, A.; Armstrong, D.; Barrado, D.; Brown, D.; Deleuil, M.; Lillo, J.; Osborn, H.; Pollacco, D.; Abe, L.; Andre, P.; Bendjoya, P.; Boisse, I.; Bonomo, A.; Bouchy, F.; Bruno, G.; Rey Cerda, J.; Courcoul, B.; Díaz, R.; Hebrard, G; Kirk, J.; Lachurie, J.; Lam, K.; Martinez, P.; McCormac, J.; Moutou, C.; Rajpurohit, A.; Rivet, J.-P.; Spake, J.; Suárez, O.; Toublanc, D.; Walker, S.

K2-19b & c (EPIC ) Susana Barros3 November P b ~ 8 days, R b = 7.23+/-0.6 R earth P c ~ 12 days R c = 4.21+/-0.31 R earth  Discovered in campaign 1 (Armstrong et al. 2015)  System two Neptune size planets  Very close 3:2 mean motion resonance  Constrain the masses: M b < 245 M Earth, M c < 280 M Earth

Near resonant systems 3 November 2015Susana Barros 3 -Amplitude of the TTV curve is proportional to the dynamic masses and eccentricities (Holman et al 2005, Agol 2005, Lithwick et al. 2012) - The libration period is inversely proportional to the distance to the resonance. -K2-19 is one of the closest systems to 3:2 MMR  long libration period > 1.5 years not detectable in the duration our observations Adapted from Lithwick et al. 2012

Chopping short period TTVs 3 November 2015Susana Barros 4 Kepler-88 Nesvorny et al 2013 later confirmed Barros et al 2014 TTVs short-timescale component “chopping” at synodic timescale (Nesvorný & Beaugé 2010; Nesvorný & Vokrouhlický 2014; Deck & Agol 2015). Proportional to mass ratios, lifts degeneracy  uniquely estimate the planetary masses.

LAM K2 pipeline Based on CoRoT imagette pipeline (Barros et al. 2014) Optimised aperture to maximise S/N (e.g. Adda et al. 2000) Self-flat field correction method (Vanderburg & Jonhson 2014) Susana Barros3 November Barros et al. in prep. Poster DA.9 by Olivier Demangeon

Transit fitting K2 3 November 2015Susana Barros 6 Planet b Planet c

Follow–up transit observations Epoch cm NITES telescope La Palma Epoch m C2PU/Omicron at Calerm, France Epoch 36 - Belesta 82-cm, France Susana Barros3 November Planet b

Photodynamical model Mercury N-body Transit/RV model Likehood 3 November 2015Susana Barros 8 MCMC masses and radius of all bodies + planetary orbital parameters at reference time Almenara, J. M. et al. 2015, MNRAS, 453, 2644 Standard TTV: fit transit times  TTVs  system dynamics

Advantages Fully consistent analysis Exploit all photometric measurements (e.g. TTVs, TDVs) Doppler detection + light curve  Absolute masses Dynamics helps constrain the TTVs and TDVs  Higher precision in system parameters (Almenara et al. 2015) Less sensitive to systematics Long computation time 3 November 2015Susana Barros 9 Derived from the model gravitationally assisted Disadvantage

3 November 2015Susana Barros 10 Planet b Planet c

3 November 2015Susana Barros 11 Results Dynamically constrained – independent from stellar parameters

K2 data only: chopping is detected! Susana Barros3 November Planet b Planet c Consistent results with the results of the full dataset

Compare with traditional TTV 3 November 2015Susana Barros 13 Values agree Double uncertainties Planet b Planet c

Planetary composition 3 November 2015Susana Barros 14 M b = 44 +/- 12 M c = /- 7.0 M-R models for solid planets (Zeng et al 2013) M-R models for planets with H/He envelopes for different metal enrichment Z (Barraffe et al 2008)

Take home messages The planets have significant gaseous envelopes and K2- 19c has higher metal enrichment than K2-19b. A photodynamical model leads to a better constrain on the system parameters. Detecting short period TTVs (chopping) in K2-19 allows to constrain the system without long time coverage. Powerful tool for K2, CHEOPS, TESS… 3 November 2015Susana Barros 15 Thanks