Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076
Abstract
Context. TOI-2076 is a transiting three-planet system of sub-Neptunes orbiting a bright (G = 8.9 mag), young (340 ±80 Myr) K-type star. Although a validated planetary system, the orbits of the two outer planets were unconstrained as only two non-consecutive transits were seen in TESS photometry. This left 11 and 7 possible period aliases for each. Aims. To reveal the true orbits of these two long-period planets, precise photometry targeted on the highest-probability period aliases is required. Long-term monitoring of transits in multi-planet systems can also help constrain planetary masses through TTV measurements. Methods. We used the MonoTools package to determine which aliases to follow, and then performed space-based and ground-based photometric follow-up of TOI-2076 c and d with CHEOPS, SAINT-EX, and LCO telescopes. Results. CHEOPS observations revealed a clear detection for TOI-2076 c at P = 21.01538+0.00084 -0.00074 d, and allowed us to rule out three of the most likely period aliases for TOI-2076 d. Ground-based photometry further enabled us to rule out remaining aliases and confirm the P = 35.12537 ±0.00067 d alias. These observations also improved the radius precision of all three sub-Neptunes to 2.518 ±0.036, 3.497 ±0.043, and 3.232 ±0.063 R⊕. Our observations also revealed a clear anti-correlated TTV signal between planets b and c likely caused by their proximity to the 2:1 resonance, while planets c and d appear close to a 5:3 period commensurability, although model degeneracy meant we were unable to retrieve robust TTV masses. Their inflated radii, likely due to extended H-He atmospheres, combined with low insolation makes all three planets excellent candidates for future comparative transmission spectroscopy with JWST.
Citation
Osborn , H P , Bonfanti , A , Gandolfi , D , Hedges , C , Leleu , A , Fortier , A , Futyan , D , Gutermann , P , Maxted , P F L , Borsato , L , Collins , K A , Da Silva , J G , Chew , Y G M , Hooton , M J , Lendl , M , Parviainen , H , Salmon , S , Schanche , N , Serrano , L M , Sousa , S G , Tuson , A , Ulmer-Moll , S , Van Grootel , V , Wells , R D , Wilson , T G , Alibert , Y , Alonso , R , Anglada , G , Asquier , J , Barrado Y Navascues , D , Baumjohann , W , Beck , T , Benz , W , Biondi , F , Bonfils , X , Bouchy , F , Brandeker , A , Broeg , C , Barczy , T , Barros , S C C , Cabrera , J , Charnoz , S , Cameron , A C , Csizmadia , S , Davies , M B , Deleuil , M , Delrez , L , Demory , B O , Ehrenreich , D , Erikson , A , Fossati , L , Fridlund , M , Gillon , M , Gomez-Munoz , M A , Gudel , M , Heng , K , Hoyer , S , Isaak , K G , Kiss , L , Laskar , J , Des Etangs , A L , Lovis , C , Magrin , D , Malavolta , L , McCormac , J , Nascimbeni , V , Olofsson , G , Ottensamer , R , Pagano , I , Palle , E , Peter , G , Piazza , D , Piotto , G , Pollacco , D , Queloz , D , Ragazzoni , R , Rando , N , Rauer , H , Reimers , C , Ribas , I , Demangeon , O D S , Smith , A M S , Sabin , L , Santos , N , Scandariato , G , Schroffenegger , U , Schwarz , R P , Shporer , A , Simon , A E , Steller , M , Szabo , G M , Segransan , D , Thomas , N , Udry , S , Walter , I & Walton , N 2022 , ' Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076 ' , Astronomy and Astrophysics , vol. 664 , A156 . https://doi.org/10.1051/0004-6361/202243065
Publication
Astronomy and Astrophysics
Status
Peer reviewed
ISSN
0004-6361Type
Journal article
Description
Funding: ACC and TGW acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant ST/R003203/1.Collections
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