TY - JOUR
T1 - An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561
AU - Lacedelli, G.
AU - Malavolta, L.
AU - Borsato, L.
AU - Piotto, G.
AU - Nardiello, D.
AU - Mortier, A.
AU - Stalport, M.
AU - Collier Cameron, A.
AU - Poretti, E.
AU - Buchhave, L. A.
AU - López-Morales, M.
AU - Nascimbeni, V.
AU - Wilson, T. G.
AU - Udry, S.
AU - Latham, D. W.
AU - Bonomo, A. S.
AU - Damasso, M.
AU - Dumusque, X.
AU - Jenkins, J. M.
AU - Lovis, C.
AU - Rice, K.
AU - Sasselov, D.
AU - Winn, J. N.
AU - Andreuzzi, G.
AU - Cosentino, R.
AU - Charbonneau, D.
AU - Di Fabrizio, L.
AU - Martnez Fiorenzano, A. F.
AU - Ghedina, A.
AU - Harutyunyan, A.
AU - Lienhard, F.
AU - Micela, G.
AU - Molinari, E.
AU - Pagano, I.
AU - Pepe, F.
AU - Phillips, D. F.
AU - Pinamonti, M.
AU - Ricker, G.
AU - Scandariato, G.
AU - Sozzetti, A.
AU - Watson, C. A.
N1 - Publisher Copyright:
© 2021 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2021/3/1
Y1 - 2021/3/1
N2 - Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterization of the planetary system orbiting the late G dwarf TOI-561. After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra-short period (USP) super-Earth (TOI-561 b) with period Pb = 0.45 d, mass Mb = 1.59 ± 0.36 M and radius Rb = 1.42 ± 0.07 R, and three mini-Neptunes: TOI-561 c, with Pc = 10.78 d, Mc = 5.40 ± 0.98 M, Rc = 2.88 ± 0.09 R; TOI-561 d, with Pd = 25.6 d, Md = 11.9 ± 1.3 M, Rd = 2.53 ± 0.13 R; and TOI-561 e, with Pe = 77.2 d, Me = 16.0 ± 2.3 M, Re = 2.67 ± 0.11 R. Having a density of 3.0 ± 0.8 g cm-3, TOI-561 b is the lowest density USP planet known to date. Our N-body simulations confirm the stability of the system and predict a strong, anti-correlated, long-term transit time variation signal between planets d and e. The unusual density of the inner super-Earth and the dynamical interactions between the outer planets make TOI-561 an interesting follow-up target.
AB - Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterization of the planetary system orbiting the late G dwarf TOI-561. After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra-short period (USP) super-Earth (TOI-561 b) with period Pb = 0.45 d, mass Mb = 1.59 ± 0.36 M and radius Rb = 1.42 ± 0.07 R, and three mini-Neptunes: TOI-561 c, with Pc = 10.78 d, Mc = 5.40 ± 0.98 M, Rc = 2.88 ± 0.09 R; TOI-561 d, with Pd = 25.6 d, Md = 11.9 ± 1.3 M, Rd = 2.53 ± 0.13 R; and TOI-561 e, with Pe = 77.2 d, Me = 16.0 ± 2.3 M, Re = 2.67 ± 0.11 R. Having a density of 3.0 ± 0.8 g cm-3, TOI-561 b is the lowest density USP planet known to date. Our N-body simulations confirm the stability of the system and predict a strong, anti-correlated, long-term transit time variation signal between planets d and e. The unusual density of the inner super-Earth and the dynamical interactions between the outer planets make TOI-561 an interesting follow-up target.
KW - planets and satellites: composition
KW - planets and satellites: detection
KW - stars: individual: TOI-561 (TIC 377064495, Gaia DR2 3850421005290172416)
KW - techniques: photometric
KW - techniques: radial velocities
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U2 - 10.1093/mnras/staa3728
DO - 10.1093/mnras/staa3728
M3 - Article
AN - SCOPUS:85100809245
SN - 0035-8711
VL - 501
SP - 4148
EP - 4166
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -