The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs

Yasunori Hori; Akihiko Fukui; Teruyuki Hirano; Norio Narita; Jerome P. de Leon; Hiroyuki Tako Ishikawa; Joel D. Hartman; Giuseppe Morello; Nestor Abreu García; Leticia Álvarez Hernández; Víctor J. S. Béjar; Yéssica Calatayud-Borras; Ilaria Carleo; Gareb Enoc; Emma Esparza-Borges; Izuru Fukuda; Daniel Galán; Samuel Geraldía-González; Yuya Hayashi; Masahiro Ikoma; Kai Ikuta; Keisuke Isogai; Taiki Kagetani; Yugo Kawai; Kiyoe Kawauchi; Tadahiro Kimura; Takanori Kodama; Judith Korth; Nobuhiko Kusakabe; Andrés Laza-Ramos; John H. Livingston; Rafael Luque; Kohei Miyakawa; Mayuko Mori; Felipe Murgas; Jaume Orell-Miquel; Enric Palle; Hannu Parviainen; Alberto Peláez-Torres; Marta Puig-Subirà; Manuel Sánchez-Benavente; Paula Sosa-Guillén; Monika Stangret; Yuka Terada; Sara Muñoz Torres; Noriharu Watanabe; Gaspar Á. Bakos; Khalid Barkaoui; Charles Beichman; Zouhair Benkhaldoun; Andrew W. Boyle; David R. Ciardi; Catherine A. Clark; Karen A. Collins; Kevin I. Collins; Dennis M. Conti; Ian J.M. Crossfield; Mark E. Everett; Elise Furlan; Mourad Ghachoui; Michaël Gillon; Erica J. Gonzales; Jesus Higuera; Keith Horne; Steve B. Howell; Emmanuël Jehin; Kathryn V. Lester; Michael B. Lund; Rachel Matson; Elisabeth C. Matthews; Francisco J. Pozuelos; Boris S. Safonov; Joshua E. Schlieder; Richard P. Schwarz; Ramotholo Sefako; Gregor Srdoc; Ivan A. Strakhov; Mathilde Timmermans; William C. Waalkes; Carl Ziegler; David Charbonneau; Zahra Essack; Natalia M. Guerrero; Hiroki Harakawa; Christina Hedges; Masato Ishizuka; Jon M. Jenkins; Mihoko Konishi; Takayuki Kotani; Tomoyuki Kudo; Takashi Kurokawa; Masayuki Kuzuhara; Jun Nishikawa; Masashi Omiya; George R. Ricker; Sara Seager; Takuma Serizawa; Stephanie Striegel; Motohide Tamura; Akitoshi Ueda; Roland Vanderspek; Sébastien Vievard; Joshua N. Winn

doi:10.3847/1538-3881/ad4115

The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs

Yasunori Hori, Akihiko Fukui, Teruyuki Hirano, Norio Narita, Jerome P. de Leon, Hiroyuki Tako Ishikawa, Joel D. Hartman, Giuseppe Morello, Nestor Abreu García, Leticia Álvarez Hernández, Víctor J. S. Béjar, Yéssica Calatayud-Borras, Ilaria Carleo, Gareb Enoc, Emma Esparza-Borges, Izuru Fukuda, Daniel Galán, Samuel Geraldía-González, Yuya Hayashi, Masahiro IkomaKai Ikuta, Keisuke Isogai, Taiki Kagetani, Yugo Kawai, Kiyoe Kawauchi, Tadahiro Kimura, Takanori Kodama, Judith Korth, Nobuhiko Kusakabe, Andrés Laza-Ramos, John H. Livingston, Rafael Luque, Kohei Miyakawa, Mayuko Mori, Felipe Murgas, Jaume Orell-Miquel, Enric Palle, Hannu Parviainen, Alberto Peláez-Torres, Marta Puig-Subirà, Manuel Sánchez-Benavente, Paula Sosa-Guillén, Monika Stangret, Yuka Terada, Sara Muñoz Torres, Noriharu Watanabe, Gaspar Á. Bakos, Khalid Barkaoui, Charles Beichman, Zouhair Benkhaldoun, Andrew W. Boyle, David R. Ciardi, Catherine A. Clark, Karen A. Collins, Kevin I. Collins, Dennis M. Conti, Ian J.M. Crossfield, Mark E. Everett, Elise Furlan, Mourad Ghachoui, Michaël Gillon, Erica J. Gonzales, Jesus Higuera, Keith Horne, Steve B. Howell, Emmanuël Jehin, Kathryn V. Lester, Michael B. Lund, Rachel Matson, Elisabeth C. Matthews, Francisco J. Pozuelos, Boris S. Safonov, Joshua E. Schlieder, Richard P. Schwarz, Ramotholo Sefako, Gregor Srdoc, Ivan A. Strakhov, Mathilde Timmermans, William C. Waalkes, Carl Ziegler, David Charbonneau, Zahra Essack, Natalia M. Guerrero, Hiroki Harakawa, Christina Hedges, Masato Ishizuka, Jon M. Jenkins, Mihoko Konishi, Takayuki Kotani, Tomoyuki Kudo, Takashi Kurokawa, Masayuki Kuzuhara, Jun Nishikawa, Masashi Omiya, George R. Ricker, Sara Seager, Takuma Serizawa, Stephanie Striegel, Motohide Tamura, Akitoshi Ueda, Roland Vanderspek, Sébastien Vievard, Joshua N. Winn

Research output: Contribution to journal › Article › peer-review

Abstract

Sub-Neptunes with radii of 2–3 R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of Rp = 2.740 ^+0.082_-0.079R⊕, 2.769^+0.073_-0.068 R⊕, 2.120 ± 0.067 R⊕, and 2.830^+0.068_-0.066 R⊕ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M⊕, <19.5 M⊕, <6.8 M⊕, and <15.6 M⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass–radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called "radius valley," are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2–0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.

Original language	English
Article number	289
Number of pages	25
Journal	Astronomical Journal
Volume	167
Issue number	6
Early online date	30 May 2024
DOIs	https://doi.org/10.3847/1538-3881/ad4115
Publication status	Published - 3 Jun 2024

Keywords

Exoplanets
Mini Neptunes
Radial velocity
Transit photometry
Tides
M dwarf stars

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Copyright © 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Final published version, 11.9 MBLicence: CC BY

https://arxiv.org/abs/2405.12637

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Hori, Y., Fukui, A., Hirano, T., Narita, N., de Leon, J. P., Ishikawa, H. T., Hartman, J. D., Morello, G., García, N. A., Hernández, L. Á., Béjar, V. J. S., Calatayud-Borras, Y., Carleo, I., Enoc, G., Esparza-Borges, E., Fukuda, I., Galán, D., Geraldía-González, S., Hayashi, Y., ... Winn, J. N. (2024). The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs. Astronomical Journal, 167(6), Article 289. https://doi.org/10.3847/1538-3881/ad4115

@article{b28b4bfd8632481c81e813773bd1486b,

title = "The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs",

abstract = "Sub-Neptunes with radii of 2–3 R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of Rp = 2.740 +0.082-0.079 R⊕, 2.769+0.073-0.068 R⊕, 2.120 ± 0.067 R⊕, and 2.830+0.068-0.066 R⊕ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M⊕, <19.5 M⊕, <6.8 M⊕, and <15.6 M⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass–radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called {"}radius valley,{"} are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2–0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.",

keywords = "Exoplanets, Mini Neptunes, Radial velocity, Transit photometry, Tides, M dwarf stars",

author = "Yasunori Hori and Akihiko Fukui and Teruyuki Hirano and Norio Narita and {de Leon}, {Jerome P.} and Ishikawa, {Hiroyuki Tako} and Hartman, {Joel D.} and Giuseppe Morello and Garc{\'i}a, {Nestor Abreu} and Hern{\'a}ndez, {Leticia {\'A}lvarez} and B{\'e}jar, {V{\'i}ctor J. S.} and Y{\'e}ssica Calatayud-Borras and Ilaria Carleo and Gareb Enoc and Emma Esparza-Borges and Izuru Fukuda and Daniel Gal{\'a}n and Samuel Gerald{\'i}a-Gonz{\'a}lez and Yuya Hayashi and Masahiro Ikoma and Kai Ikuta and Keisuke Isogai and Taiki Kagetani and Yugo Kawai and Kiyoe Kawauchi and Tadahiro Kimura and Takanori Kodama and Judith Korth and Nobuhiko Kusakabe and Andr{\'e}s Laza-Ramos and Livingston, {John H.} and Rafael Luque and Kohei Miyakawa and Mayuko Mori and Felipe Murgas and Jaume Orell-Miquel and Enric Palle and Hannu Parviainen and Alberto Pel{\'a}ez-Torres and Marta Puig-Subir{\`a} and Manuel S{\'a}nchez-Benavente and Paula Sosa-Guill{\'e}n and Monika Stangret and Yuka Terada and {Mu{\~n}oz Torres}, Sara and Noriharu Watanabe and Bakos, {Gaspar {\'A}.} and Khalid Barkaoui and Charles Beichman and Zouhair Benkhaldoun and Boyle, {Andrew W.} and Ciardi, {David R.} and Clark, {Catherine A.} and Collins, {Karen A.} and Collins, {Kevin I.} and Conti, {Dennis M.} and Crossfield, {Ian J.M.} and Everett, {Mark E.} and Elise Furlan and Mourad Ghachoui and Micha{\"e}l Gillon and Gonzales, {Erica J.} and Jesus Higuera and Keith Horne and Howell, {Steve B.} and Emmanu{\"e}l Jehin and Lester, {Kathryn V.} and Lund, {Michael B.} and Rachel Matson and Matthews, {Elisabeth C.} and Pozuelos, {Francisco J.} and Safonov, {Boris S.} and Schlieder, {Joshua E.} and Schwarz, {Richard P.} and Ramotholo Sefako and Gregor Srdoc and Strakhov, {Ivan A.} and Mathilde Timmermans and Waalkes, {William C.} and Carl Ziegler and David Charbonneau and Zahra Essack and Guerrero, {Natalia M.} and Hiroki Harakawa and Christina Hedges and Masato Ishizuka and Jenkins, {Jon M.} and Mihoko Konishi and Takayuki Kotani and Tomoyuki Kudo and Takashi Kurokawa and Masayuki Kuzuhara and Jun Nishikawa and Masashi Omiya and Ricker, {George R.} and Sara Seager and Takuma Serizawa and Stephanie Striegel and Motohide Tamura and Akitoshi Ueda and Roland Vanderspek and S{\'e}bastien Vievard and Winn, {Joshua N.}",

year = "2024",

month = jun,

day = "3",

doi = "10.3847/1538-3881/ad4115",

language = "English",

volume = "167",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "6",

}

Hori, Y, Fukui, A, Hirano, T, Narita, N, de Leon, JP, Ishikawa, HT, Hartman, JD, Morello, G, García, NA, Hernández, LÁ, Béjar, VJS, Calatayud-Borras, Y, Carleo, I, Enoc, G, Esparza-Borges, E, Fukuda, I, Galán, D, Geraldía-González, S, Hayashi, Y, Ikoma, M, Ikuta, K, Isogai, K, Kagetani, T, Kawai, Y, Kawauchi, K, Kimura, T, Kodama, T, Korth, J, Kusakabe, N, Laza-Ramos, A, Livingston, JH, Luque, R, Miyakawa, K, Mori, M, Murgas, F, Orell-Miquel, J, Palle, E, Parviainen, H, Peláez-Torres, A, Puig-Subirà, M, Sánchez-Benavente, M, Sosa-Guillén, P, Stangret, M, Terada, Y, Muñoz Torres, S, Watanabe, N, Bakos, GÁ, Barkaoui, K, Beichman, C, Benkhaldoun, Z, Boyle, AW, Ciardi, DR, Clark, CA, Collins, KA, Collins, KI, Conti, DM, Crossfield, IJM, Everett, ME, Furlan, E, Ghachoui, M, Gillon, M, Gonzales, EJ, Higuera, J, Horne, K, Howell, SB, Jehin, E, Lester, KV, Lund, MB, Matson, R, Matthews, EC, Pozuelos, FJ, Safonov, BS, Schlieder, JE, Schwarz, RP, Sefako, R, Srdoc, G, Strakhov, IA, Timmermans, M, Waalkes, WC, Ziegler, C, Charbonneau, D, Essack, Z, Guerrero, NM, Harakawa, H, Hedges, C, Ishizuka, M, Jenkins, JM, Konishi, M, Kotani, T, Kudo, T, Kurokawa, T, Kuzuhara, M, Nishikawa, J, Omiya, M, Ricker, GR, Seager, S, Serizawa, T, Striegel, S, Tamura, M, Ueda, A, Vanderspek, R, Vievard, S & Winn, JN 2024, 'The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs', Astronomical Journal, vol. 167, no. 6, 289. https://doi.org/10.3847/1538-3881/ad4115

TY - JOUR

T1 - The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs

AU - Hori, Yasunori

AU - Fukui, Akihiko

AU - Hirano, Teruyuki

AU - Narita, Norio

AU - de Leon, Jerome P.

AU - Ishikawa, Hiroyuki Tako

AU - Hartman, Joel D.

AU - Morello, Giuseppe

AU - García, Nestor Abreu

AU - Hernández, Leticia Álvarez

AU - Béjar, Víctor J. S.

AU - Calatayud-Borras, Yéssica

AU - Carleo, Ilaria

AU - Enoc, Gareb

AU - Esparza-Borges, Emma

AU - Fukuda, Izuru

AU - Galán, Daniel

AU - Geraldía-González, Samuel

AU - Hayashi, Yuya

AU - Ikoma, Masahiro

AU - Ikuta, Kai

AU - Isogai, Keisuke

AU - Kagetani, Taiki

AU - Kawai, Yugo

AU - Kawauchi, Kiyoe

AU - Kimura, Tadahiro

AU - Kodama, Takanori

AU - Korth, Judith

AU - Kusakabe, Nobuhiko

AU - Laza-Ramos, Andrés

AU - Livingston, John H.

AU - Luque, Rafael

AU - Miyakawa, Kohei

AU - Mori, Mayuko

AU - Murgas, Felipe

AU - Orell-Miquel, Jaume

AU - Palle, Enric

AU - Parviainen, Hannu

AU - Peláez-Torres, Alberto

AU - Puig-Subirà, Marta

AU - Sánchez-Benavente, Manuel

AU - Sosa-Guillén, Paula

AU - Stangret, Monika

AU - Terada, Yuka

AU - Muñoz Torres, Sara

AU - Watanabe, Noriharu

AU - Bakos, Gaspar Á.

AU - Barkaoui, Khalid

AU - Beichman, Charles

AU - Benkhaldoun, Zouhair

AU - Boyle, Andrew W.

AU - Ciardi, David R.

AU - Clark, Catherine A.

AU - Collins, Karen A.

AU - Collins, Kevin I.

AU - Conti, Dennis M.

AU - Crossfield, Ian J.M.

AU - Everett, Mark E.

AU - Furlan, Elise

AU - Ghachoui, Mourad

AU - Gillon, Michaël

AU - Gonzales, Erica J.

AU - Higuera, Jesus

AU - Horne, Keith

AU - Howell, Steve B.

AU - Jehin, Emmanuël

AU - Lester, Kathryn V.

AU - Lund, Michael B.

AU - Matson, Rachel

AU - Matthews, Elisabeth C.

AU - Pozuelos, Francisco J.

AU - Safonov, Boris S.

AU - Schlieder, Joshua E.

AU - Schwarz, Richard P.

AU - Sefako, Ramotholo

AU - Srdoc, Gregor

AU - Strakhov, Ivan A.

AU - Timmermans, Mathilde

AU - Waalkes, William C.

AU - Ziegler, Carl

AU - Charbonneau, David

AU - Essack, Zahra

AU - Guerrero, Natalia M.

AU - Harakawa, Hiroki

AU - Hedges, Christina

AU - Ishizuka, Masato

AU - Jenkins, Jon M.

AU - Konishi, Mihoko

AU - Kotani, Takayuki

AU - Kudo, Tomoyuki

AU - Kurokawa, Takashi

AU - Kuzuhara, Masayuki

AU - Nishikawa, Jun

AU - Omiya, Masashi

AU - Ricker, George R.

AU - Seager, Sara

AU - Serizawa, Takuma

AU - Striegel, Stephanie

AU - Tamura, Motohide

AU - Ueda, Akitoshi

AU - Vanderspek, Roland

AU - Vievard, Sébastien

AU - Winn, Joshua N.

PY - 2024/6/3

Y1 - 2024/6/3

N2 - Sub-Neptunes with radii of 2–3 R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of Rp = 2.740 +0.082-0.079 R⊕, 2.769+0.073-0.068 R⊕, 2.120 ± 0.067 R⊕, and 2.830+0.068-0.066 R⊕ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M⊕, <19.5 M⊕, <6.8 M⊕, and <15.6 M⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass–radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called "radius valley," are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2–0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.

AB - Sub-Neptunes with radii of 2–3 R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of Rp = 2.740 +0.082-0.079 R⊕, 2.769+0.073-0.068 R⊕, 2.120 ± 0.067 R⊕, and 2.830+0.068-0.066 R⊕ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M⊕, <19.5 M⊕, <6.8 M⊕, and <15.6 M⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass–radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called "radius valley," are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2–0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.

KW - Exoplanets

KW - Mini Neptunes

KW - Radial velocity

KW - Transit photometry

KW - Tides

KW - M dwarf stars

U2 - 10.3847/1538-3881/ad4115

DO - 10.3847/1538-3881/ad4115

M3 - Article

SN - 0004-6256

VL - 167

JO - Astronomical Journal

JF - Astronomical Journal

IS - 6

M1 - 289

ER -

The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs

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