TY - JOUR
T1 - Masses, Revised Radii, and a Third Planet Candidate in the "Inverted" Planetary System Around TOI-1266
AU - Cloutier, Ryan
AU - Greklek-McKeon, Michael
AU - Wurmser, Serena
AU - Cherubim, Collin
AU - Gillis, Erik
AU - Vanderburg, Andrew
AU - Hadden, Sam
AU - Cadieux, Charles
AU - Artigau, Étienne
AU - Vissapragada, Shreyas
AU - Mortier, Annelies
AU - López-Morales, Mercedes
AU - Latham, David W.
AU - Knutson, Heather
AU - Haywood, Raphaëlle D.
AU - Pallé, Enric
AU - Doyon, René
AU - Cook, Neil
AU - Andreuzzi, Gloria
AU - Cecconi, Massimo
AU - Cosentino, Rosario
AU - Ghedina, Adriano
AU - Harutyunyan, Avet
AU - Pinamonti, Matteo
AU - Stalport, Manu
AU - Damasso, Mario
AU - Rescigno, Federica
AU - Wilson, Thomas G.
AU - Buchhave, Lars A.
AU - Charbonneau, David
AU - Cameron, Andrew Collier
AU - Dumusque, Xavier
AU - Lovis, Christophe
AU - Mayor, Michel
AU - Molinari, Emilio
AU - Pepe, Francesco
AU - Piotto, Giampaolo
AU - Rice, Ken
AU - Sasselov, Dimitar
AU - Ségransan, Damien
AU - Sozzetti, Alessandro
AU - Udry, Stéphane
AU - Watson, Chris A.
N1 - Accepted for publication in MNRAS. 21 pages. Our spectroscopic time series are included in the arXiv source files as table6.csv
PY - 2023/11/8
Y1 - 2023/11/8
N2 - Is the population of close-in planets orbiting M dwarfs sculpted by thermally driven escape or is it a direct outcome of the planet formation process? A number of recent empirical results strongly suggest the latter. However, the unique architecture of the TOI-1266 system presents a challenge to models of planet formation and atmospheric escape given its seemingly “inverted” architecture of a large sub-Neptune (Pb = 10.9 days, Rp, b = 2.62 ± 0.11 R⊕) orbiting interior to that of the system’s smaller planet (Pc = 18.8 days, Rp, c = 2.13 ± 0.12 R⊕). Here we present revised planetary radii based on new TESS and diffuser-assisted ground-based transit observations, and characterize both planetary masses using a set of 145 radial velocity measurements from HARPS-N (Mp, b = 4.23 ± 0.69 M⊕, Mp, c = 2.88 ± 0.80 M⊕). Our analysis also reveals a third planet candidate (Pd = 32.3 days, Mp,dsini=4.59+0.96−0.94M⊕), which if real, would form a chain of near 5:3 period ratios, although the system is likely not in a mean motion resonance. Our results indicate that TOI-1266 b and c are among the lowest density sub-Neptunes around M dwarfs and likely exhibit distinct bulk compositions of a gas-enveloped terrestrial (Xenv, b = 5.5 ± 0.7%) and a water-rich world (WMFc = 59 ± 14%), which is supported by hydrodynamic escape models. If distinct bulk compositions are confirmed through atmospheric characterization, the system’s unique architecture would represent an interesting test case of inside-out sub-Neptune formation at pebble traps.
AB - Is the population of close-in planets orbiting M dwarfs sculpted by thermally driven escape or is it a direct outcome of the planet formation process? A number of recent empirical results strongly suggest the latter. However, the unique architecture of the TOI-1266 system presents a challenge to models of planet formation and atmospheric escape given its seemingly “inverted” architecture of a large sub-Neptune (Pb = 10.9 days, Rp, b = 2.62 ± 0.11 R⊕) orbiting interior to that of the system’s smaller planet (Pc = 18.8 days, Rp, c = 2.13 ± 0.12 R⊕). Here we present revised planetary radii based on new TESS and diffuser-assisted ground-based transit observations, and characterize both planetary masses using a set of 145 radial velocity measurements from HARPS-N (Mp, b = 4.23 ± 0.69 M⊕, Mp, c = 2.88 ± 0.80 M⊕). Our analysis also reveals a third planet candidate (Pd = 32.3 days, Mp,dsini=4.59+0.96−0.94M⊕), which if real, would form a chain of near 5:3 period ratios, although the system is likely not in a mean motion resonance. Our results indicate that TOI-1266 b and c are among the lowest density sub-Neptunes around M dwarfs and likely exhibit distinct bulk compositions of a gas-enveloped terrestrial (Xenv, b = 5.5 ± 0.7%) and a water-rich world (WMFc = 59 ± 14%), which is supported by hydrodynamic escape models. If distinct bulk compositions are confirmed through atmospheric characterization, the system’s unique architecture would represent an interesting test case of inside-out sub-Neptune formation at pebble traps.
KW - astro-ph.EP
U2 - 10.1093/mnras/stad3450
DO - 10.1093/mnras/stad3450
M3 - Article
SN - 0035-8711
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
M1 - stad3450
ER -