Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076

Journal
Date Issued
2022
Author(s)
Osborn, H.P.
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Bonfanti, A.
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Gandolfi, D.
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Hedges, C.
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Leleu, A.
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Fortier, A.
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Futyan, D.
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Gutermann, P.
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Maxted, P.F.L.
•
•
Collins, K.A.
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Da Silva, J.G.
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Chew, Y.G.M.
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Hooton, M.J.
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Lendl, M.
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Parviainen, H.
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Salmon, S.
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Schanche, N.
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Serrano, L.M.
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Sousa, S.G.
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Tuson, A.
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Ulmer-Moll, S.
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Van Grootel, V.
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Wells, R.D.
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Wilson, T.G.
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Alibert, Y.
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Alonso, R.
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Anglada, G.
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Asquier, J.
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Barrado Y Navascues, D.
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Baumjohann, W.
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Beck, T.
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Benz, W.
•
•
Bonfils, X.
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Bouchy, F.
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Brandeker, A.
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Broeg, C.
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Barczy, T.
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Barros, S.C.C.
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Cabrera, J.
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Charnoz, S.
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Cameron, A.C.
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Csizmadia, S.
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Davies, M.B.
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Deleuil, M.
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Delrez, L.
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Demory, B.-O.
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Ehrenreich, D.
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Erikson, A.
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Fossati, L.
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Fridlund, M.
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Gillon, M.
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Gomez-Munoz, M.A.
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Gudel, M.
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Heng, K.
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Hoyer, S.
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Isaak, K.G.
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Kiss, L.
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Laskar, J.
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Des Etangs, A.L.
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Lovis, C.
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•
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McCormac, J.
•
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Olofsson, G.
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Ottensamer, R.
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Palle, E.
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Peter, G.
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Piazza, D.
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Piotto, G.
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Pollacco, D.
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Queloz, D.
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Rando, N.
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Rauer, H.
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Reimers, C.
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Ribas, I.
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Demangeon, O.D.S.
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Smith, A.M.S.
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Sabin, L.
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Santos, N.
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Schroffenegger, U.
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Schwarz, R.P.
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Shporer, A.
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Simon, A.E.
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Steller, M.
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Szabo, G.M.
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Segransan, D.
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Thomas, N.
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Udry, S.
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Walter, I.
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Walton, N.
DOI
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.
Volume
664
Start page
A156
Uri
Url
Issn Identifier
0004-6361
Rights
open.access
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