A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776

R. Luque; L. M. Serrano; K. Molaverdikhani; M. C. Nixon; J. H. Livingston; E. W. Guenther; E. Pallé; N. Madhusudhan; G. Nowak; J. Korth; W. D. Cochran; T. Hirano; P. Chaturvedi; E. Goffo; S. Albrecht; O. Barragán; C. Briceño; J. Cabrera; D. Charbonneau; R. Cloutier; K. A. Collins; K. I. Collins; K. D. Colón; I. J.M. Crossfield; Sz Csizmadia; F. Dai; H. J. Deeg; M. Esposito; M. Fridlund; D. Gandolfi; I. Georgieva; A. Glidden; R. F. Goeke; S. Grziwa; A. P. Hatzes; C. E. Henze; S. B. Howell; J. Irwin; J. M. Jenkins; E. L.N. Jensen; P. Kábath; R. C. Kidwell; J. F. Kielkopf; E. Knudstrup; K. W.F. Lam; D. W. Latham; J. J. Lissauer; A. W. Mann; E. C. Matthews; I. Mireles; N. Narita; M. Paegert; C. M. Persson; S. Redfield; G. R. Ricker; F. Rodler; J. E. Schlieder; N. J. Scott; S. Seager; J. Šubjak; T. G. Tan; E. B. Ting; R. Vanderspek; V. Van Eylen; J. N. Winn; C. Ziegler

doi:10.1051/0004-6361/202039455

A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776

R. Luque, L. M. Serrano, K. Molaverdikhani, M. C. Nixon, J. H. Livingston, E. W. Guenther, E. Pallé, N. Madhusudhan, G. Nowak, J. Korth, W. D. Cochran, T. Hirano, P. Chaturvedi, E. Goffo, S. Albrecht, O. Barragán, C. Briceño, J. Cabrera, D. Charbonneau, R. CloutierK. A. Collins, K. I. Collins, K. D. Colón, I. J.M. Crossfield, Sz Csizmadia, F. Dai, H. J. Deeg, M. Esposito, M. Fridlund, D. Gandolfi, I. Georgieva, A. Glidden, R. F. Goeke, S. Grziwa, A. P. Hatzes, C. E. Henze, S. B. Howell, J. Irwin, J. M. Jenkins, E. L.N. Jensen, P. Kábath, R. C. Kidwell, J. F. Kielkopf, E. Knudstrup, K. W.F. Lam, D. W. Latham, J. J. Lissauer, A. W. Mann, E. C. Matthews, I. Mireles, N. Narita, M. Paegert, C. M. Persson, S. Redfield, G. R. Ricker, F. Rodler, J. E. Schlieder, N. J. Scott, S. Seager, J. Šubjak, T. G. Tan, E. B. Ting, R. Vanderspek, V. Van Eylen, J. N. Winn, C. Ziegler

Astrophysical Sciences

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Abstract

We report the discovery and characterization of two transiting planets around the bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M = 0.54 ± 0.03 M⊙) detected during Sector 10 observations of the Transiting Exoplanet Survey Satellite (TESS). Combining the TESS photometry with HARPS radial velocities, as well as ground-based follow-up transit observations from the MEarth and LCOGT telescopes, for the inner planet, TOI-776 b, we measured a period of Pb = 8.25 d, a radius of Rb = 1.85 ± 0.13 R⊙, and a mass of Mb = 4.0 ± 0.9 M⊙; and for the outer planet, TOI-776 c, a period of Pc = 15.66 d, a radius of Rc = 2.02 ± 0.14 R⊙, and a mass of Mc = 5.3 ± 1.8 M⊙. The Doppler data shows one additional signal, with a period of ~34 d, associated with the rotational period of the star. The analysis of fifteen years of ground-based photometric monitoring data and the inspection of different spectral line indicators confirm this assumption. The bulk densities of TOI-776 b and c allow for a wide range of possible interior and atmospheric compositions. However, both planets have retained a significant atmosphere, with slightly different envelope mass fractions. Thanks to their location near the radius gap for M dwarfs, we can start to explore the mechanism(s) responsible for the radius valley emergence around low-mass stars as compared to solar-like stars. While a larger sample of well-characterized planets in this parameter space is still needed to draw firm conclusions, we tentatively estimate that the stellar mass below which thermally-driven mass loss is no longer the main formation pathway for sculpting the radius valley is between 0.63 and 0.54 M⊙. Due to the brightness of the star, the TOI-776 system is also an excellent target for the James Webb Space Telescope, providing a remarkable laboratory in which to break the degeneracy in planetary interior models and to test formation and evolution theories of small planets around low-mass stars.

Original language	English (US)
Article number	A41
Journal	Astronomy and Astrophysics
Volume	645
DOIs	https://doi.org/10.1051/0004-6361/202039455
State	Published - Jan 1 2021

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

Planetary systems
Stars: individual: LP 961-53
Stars: low-mass
Techniques: photometric
Techniques: radial velocities

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10.1051/0004-6361/202039455

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Luque, R., Serrano, L. M., Molaverdikhani, K., Nixon, M. C., Livingston, J. H., Guenther, E. W., Pallé, E., Madhusudhan, N., Nowak, G., Korth, J., Cochran, W. D., Hirano, T., Chaturvedi, P., Goffo, E., Albrecht, S., Barragán, O., Briceño, C., Cabrera, J., Charbonneau, D., ... Ziegler, C. (2021). A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776. Astronomy and Astrophysics, 645, Article A41. https://doi.org/10.1051/0004-6361/202039455

@article{e07081fa6938436a8c9540e381b5e1aa,

title = "A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776",

abstract = "We report the discovery and characterization of two transiting planets around the bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M = 0.54 ± 0.03 M⊙) detected during Sector 10 observations of the Transiting Exoplanet Survey Satellite (TESS). Combining the TESS photometry with HARPS radial velocities, as well as ground-based follow-up transit observations from the MEarth and LCOGT telescopes, for the inner planet, TOI-776 b, we measured a period of Pb = 8.25 d, a radius of Rb = 1.85 ± 0.13 R⊙, and a mass of Mb = 4.0 ± 0.9 M⊙; and for the outer planet, TOI-776 c, a period of Pc = 15.66 d, a radius of Rc = 2.02 ± 0.14 R⊙, and a mass of Mc = 5.3 ± 1.8 M⊙. The Doppler data shows one additional signal, with a period of ~34 d, associated with the rotational period of the star. The analysis of fifteen years of ground-based photometric monitoring data and the inspection of different spectral line indicators confirm this assumption. The bulk densities of TOI-776 b and c allow for a wide range of possible interior and atmospheric compositions. However, both planets have retained a significant atmosphere, with slightly different envelope mass fractions. Thanks to their location near the radius gap for M dwarfs, we can start to explore the mechanism(s) responsible for the radius valley emergence around low-mass stars as compared to solar-like stars. While a larger sample of well-characterized planets in this parameter space is still needed to draw firm conclusions, we tentatively estimate that the stellar mass below which thermally-driven mass loss is no longer the main formation pathway for sculpting the radius valley is between 0.63 and 0.54 M⊙. Due to the brightness of the star, the TOI-776 system is also an excellent target for the James Webb Space Telescope, providing a remarkable laboratory in which to break the degeneracy in planetary interior models and to test formation and evolution theories of small planets around low-mass stars.",

keywords = "Planetary systems, Stars: individual: LP 961-53, Stars: low-mass, Techniques: photometric, Techniques: radial velocities",

author = "R. Luque and Serrano, {L. M.} and K. Molaverdikhani and Nixon, {M. C.} and Livingston, {J. H.} and Guenther, {E. W.} and E. Pall{\'e} and N. Madhusudhan and G. Nowak and J. Korth and Cochran, {W. D.} and T. Hirano and P. Chaturvedi and E. Goffo and S. Albrecht and O. Barrag{\'a}n and C. Brice{\~n}o and J. Cabrera and D. Charbonneau and R. Cloutier and Collins, {K. A.} and Collins, {K. I.} and Col{\'o}n, {K. D.} and Crossfield, {I. J.M.} and Sz Csizmadia and F. Dai and Deeg, {H. J.} and M. Esposito and M. Fridlund and D. Gandolfi and I. Georgieva and A. Glidden and Goeke, {R. F.} and S. Grziwa and Hatzes, {A. P.} and Henze, {C. E.} and Howell, {S. B.} and J. Irwin and Jenkins, {J. M.} and Jensen, {E. L.N.} and P. K{\'a}bath and Kidwell, {R. C.} and Kielkopf, {J. F.} and E. Knudstrup and Lam, {K. W.F.} and Latham, {D. W.} and Lissauer, {J. J.} and Mann, {A. W.} and Matthews, {E. C.} and I. Mireles and N. Narita and M. Paegert and Persson, {C. M.} and S. Redfield and Ricker, {G. R.} and F. Rodler and Schlieder, {J. E.} and Scott, {N. J.} and S. Seager and J. {\v S}ubjak and Tan, {T. G.} and Ting, {E. B.} and R. Vanderspek and {Van Eylen}, V. and Winn, {J. N.} and C. Ziegler",

note = "Publisher Copyright: {\textcopyright} ESO 2021.",

year = "2021",

month = jan,

day = "1",

doi = "10.1051/0004-6361/202039455",

language = "English (US)",

volume = "645",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Luque, R, Serrano, LM, Molaverdikhani, K, Nixon, MC, Livingston, JH, Guenther, EW, Pallé, E, Madhusudhan, N, Nowak, G, Korth, J, Cochran, WD, Hirano, T, Chaturvedi, P, Goffo, E, Albrecht, S, Barragán, O, Briceño, C, Cabrera, J, Charbonneau, D, Cloutier, R, Collins, KA, Collins, KI, Colón, KD, Crossfield, IJM, Csizmadia, S, Dai, F, Deeg, HJ, Esposito, M, Fridlund, M, Gandolfi, D, Georgieva, I, Glidden, A, Goeke, RF, Grziwa, S, Hatzes, AP, Henze, CE, Howell, SB, Irwin, J, Jenkins, JM, Jensen, ELN, Kábath, P, Kidwell, RC, Kielkopf, JF, Knudstrup, E, Lam, KWF, Latham, DW, Lissauer, JJ, Mann, AW, Matthews, EC, Mireles, I, Narita, N, Paegert, M, Persson, CM, Redfield, S, Ricker, GR, Rodler, F, Schlieder, JE, Scott, NJ, Seager, S, Šubjak, J, Tan, TG, Ting, EB, Vanderspek, R, Van Eylen, V, Winn, JN & Ziegler, C 2021, 'A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776', Astronomy and Astrophysics, vol. 645, A41. https://doi.org/10.1051/0004-6361/202039455

TY - JOUR

T1 - A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776

AU - Luque, R.

AU - Serrano, L. M.

AU - Molaverdikhani, K.

AU - Nixon, M. C.

AU - Livingston, J. H.

AU - Guenther, E. W.

AU - Pallé, E.

AU - Madhusudhan, N.

AU - Nowak, G.

AU - Korth, J.

AU - Cochran, W. D.

AU - Hirano, T.

AU - Chaturvedi, P.

AU - Goffo, E.

AU - Albrecht, S.

AU - Barragán, O.

AU - Briceño, C.

AU - Cabrera, J.

AU - Charbonneau, D.

AU - Cloutier, R.

AU - Collins, K. A.

AU - Collins, K. I.

AU - Colón, K. D.

AU - Crossfield, I. J.M.

AU - Csizmadia, Sz

AU - Dai, F.

AU - Deeg, H. J.

AU - Esposito, M.

AU - Fridlund, M.

AU - Gandolfi, D.

AU - Georgieva, I.

AU - Glidden, A.

AU - Goeke, R. F.

AU - Grziwa, S.

AU - Hatzes, A. P.

AU - Henze, C. E.

AU - Howell, S. B.

AU - Irwin, J.

AU - Jenkins, J. M.

AU - Jensen, E. L.N.

AU - Kábath, P.

AU - Kidwell, R. C.

AU - Kielkopf, J. F.

AU - Knudstrup, E.

AU - Lam, K. W.F.

AU - Latham, D. W.

AU - Lissauer, J. J.

AU - Mann, A. W.

AU - Matthews, E. C.

AU - Mireles, I.

AU - Narita, N.

AU - Paegert, M.

AU - Persson, C. M.

AU - Redfield, S.

AU - Ricker, G. R.

AU - Rodler, F.

AU - Schlieder, J. E.

AU - Scott, N. J.

AU - Seager, S.

AU - Šubjak, J.

AU - Tan, T. G.

AU - Ting, E. B.

AU - Vanderspek, R.

AU - Van Eylen, V.

AU - Winn, J. N.

AU - Ziegler, C.

PY - 2021/1/1

Y1 - 2021/1/1

N2 - We report the discovery and characterization of two transiting planets around the bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M = 0.54 ± 0.03 M⊙) detected during Sector 10 observations of the Transiting Exoplanet Survey Satellite (TESS). Combining the TESS photometry with HARPS radial velocities, as well as ground-based follow-up transit observations from the MEarth and LCOGT telescopes, for the inner planet, TOI-776 b, we measured a period of Pb = 8.25 d, a radius of Rb = 1.85 ± 0.13 R⊙, and a mass of Mb = 4.0 ± 0.9 M⊙; and for the outer planet, TOI-776 c, a period of Pc = 15.66 d, a radius of Rc = 2.02 ± 0.14 R⊙, and a mass of Mc = 5.3 ± 1.8 M⊙. The Doppler data shows one additional signal, with a period of ~34 d, associated with the rotational period of the star. The analysis of fifteen years of ground-based photometric monitoring data and the inspection of different spectral line indicators confirm this assumption. The bulk densities of TOI-776 b and c allow for a wide range of possible interior and atmospheric compositions. However, both planets have retained a significant atmosphere, with slightly different envelope mass fractions. Thanks to their location near the radius gap for M dwarfs, we can start to explore the mechanism(s) responsible for the radius valley emergence around low-mass stars as compared to solar-like stars. While a larger sample of well-characterized planets in this parameter space is still needed to draw firm conclusions, we tentatively estimate that the stellar mass below which thermally-driven mass loss is no longer the main formation pathway for sculpting the radius valley is between 0.63 and 0.54 M⊙. Due to the brightness of the star, the TOI-776 system is also an excellent target for the James Webb Space Telescope, providing a remarkable laboratory in which to break the degeneracy in planetary interior models and to test formation and evolution theories of small planets around low-mass stars.

AB - We report the discovery and characterization of two transiting planets around the bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M = 0.54 ± 0.03 M⊙) detected during Sector 10 observations of the Transiting Exoplanet Survey Satellite (TESS). Combining the TESS photometry with HARPS radial velocities, as well as ground-based follow-up transit observations from the MEarth and LCOGT telescopes, for the inner planet, TOI-776 b, we measured a period of Pb = 8.25 d, a radius of Rb = 1.85 ± 0.13 R⊙, and a mass of Mb = 4.0 ± 0.9 M⊙; and for the outer planet, TOI-776 c, a period of Pc = 15.66 d, a radius of Rc = 2.02 ± 0.14 R⊙, and a mass of Mc = 5.3 ± 1.8 M⊙. The Doppler data shows one additional signal, with a period of ~34 d, associated with the rotational period of the star. The analysis of fifteen years of ground-based photometric monitoring data and the inspection of different spectral line indicators confirm this assumption. The bulk densities of TOI-776 b and c allow for a wide range of possible interior and atmospheric compositions. However, both planets have retained a significant atmosphere, with slightly different envelope mass fractions. Thanks to their location near the radius gap for M dwarfs, we can start to explore the mechanism(s) responsible for the radius valley emergence around low-mass stars as compared to solar-like stars. While a larger sample of well-characterized planets in this parameter space is still needed to draw firm conclusions, we tentatively estimate that the stellar mass below which thermally-driven mass loss is no longer the main formation pathway for sculpting the radius valley is between 0.63 and 0.54 M⊙. Due to the brightness of the star, the TOI-776 system is also an excellent target for the James Webb Space Telescope, providing a remarkable laboratory in which to break the degeneracy in planetary interior models and to test formation and evolution theories of small planets around low-mass stars.

KW - Planetary systems

KW - Stars: individual: LP 961-53

KW - Stars: low-mass

KW - Techniques: photometric

KW - Techniques: radial velocities

UR - http://www.scopus.com/inward/record.url?scp=85099057388&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85099057388&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202039455

DO - 10.1051/0004-6361/202039455

M3 - Article

AN - SCOPUS:85099057388

SN - 0004-6361

VL - 645

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A41

ER -

A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776

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