Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

Varghese Reji; Shubham Kanodia; Joe P. Ninan; Caleb I. Cañas; Jessica Libby-Roberts; Andrea S. J. Lin; Arvind F Gupta; Tera N. Sewaby; Alexander Larsen; Henry A. Kobulnicky; Philip I. Choi; Nez Evans; Sage Santomenna; Isabelle Winnick; Larry Yu; Jaime A. Alvarado-Montes; Chad F. Bender; Lia Marta Bernabò; Cullen H. Blake; William D. Cochran; Scott A. Diddams; Samuel Halverson; Te Han; Fred Hearty; Sarah E. Logsdon; Suvrath Mahadevan; Michael McElwain; Andrew Monson; Paul Robertson; Devendra K. Ojha; Arpita Roy; Christian Schwab; Gudmundur Stefansson; Jason Wright

doi:10.3847/1538-3881/ada7ea

Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

Varghese Reji, Shubham Kanodia, Joe P. Ninan, Caleb I. Cañas, Jessica Libby-Roberts, Andrea S. J. Lin, Arvind F Gupta, Tera N. Sewaby, Alexander Larsen, Henry A. Kobulnicky, Philip I. Choi, Nez Evans, Sage Santomenna, Isabelle Winnick, Larry Yu, Jaime A. Alvarado-Montes, Chad F. Bender, Lia Marta Bernabò, Cullen H. Blake, William D. CochranScott A. Diddams, Samuel Halverson, Te Han, Fred Hearty, Sarah E. Logsdon, Suvrath Mahadevan, Michael McElwain, Andrew Monson, Paul Robertson, Devendra K. Ojha, Arpita Roy, Christian Schwab, Gudmundur Stefansson, Jason Wright

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Abstract

We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets (R ≳ 8 R_⊕) through the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite, and characterized with ground-based transits from Red Buttes Observatory, the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder on the 10 m Hobby Eberly Telescope and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of 124 ± 24 M_⊕ (0.39 ± 0.07 M_J) and 10.4 ± 0.7 R_⊕ (0.92 ± 0.06 R_J), respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] = 0.47 ± 0.16 dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of ~5″ (1110 au) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems.

Original language	English
Article number	187
Pages (from-to)	187-200
Number of pages	13
Journal	The Astronomical Journal
Volume	169
Issue number	3
DOIs	https://doi.org/10.3847/1538-3881/ada7ea
Publication status	Published - 3 Mar 2025

Bibliographical note

© 2025. The Author(s). Published by the American Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

Extrasolar gaseous giant planets
M dwarf stars
Radial velocity
Transit

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Reji, V., Kanodia, S., Ninan, J. P., Cañas, C. I., Libby-Roberts, J., Lin, A. S. J., Gupta, A. F., Sewaby, T. N., Larsen, A., Kobulnicky, H. A., Choi, P. I., Evans, N., Santomenna, S., Winnick, I., Yu, L., Alvarado-Montes, J. A., Bender, C. F., Marta Bernabò, L., Blake, C. H., ... Wright, J. (2025). Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf. The Astronomical Journal, 169(3), 187-200. Article 187. https://doi.org/10.3847/1538-3881/ada7ea

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title = "Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf",

abstract = "We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets (R ≳ 8 R⊕) through the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite, and characterized with ground-based transits from Red Buttes Observatory, the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder on the 10 m Hobby Eberly Telescope and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of 124 ± 24 M⊕ (0.39 ± 0.07 MJ) and 10.4 ± 0.7 R⊕ (0.92 ± 0.06 RJ), respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] = 0.47 ± 0.16 dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of \textasciitilde{}5″ (1110 au) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems.",

keywords = "Extrasolar gaseous giant planets, M dwarf stars, Radial velocity, Transit",

author = "Varghese Reji and Shubham Kanodia and Ninan, \{Joe P.\} and Ca{\~n}as, \{Caleb I.\} and Jessica Libby-Roberts and Lin, \{Andrea S. J.\} and Gupta, \{Arvind F\} and Sewaby, \{Tera N.\} and Alexander Larsen and Kobulnicky, \{Henry A.\} and Choi, \{Philip I.\} and Nez Evans and Sage Santomenna and Isabelle Winnick and Larry Yu and Alvarado-Montes, \{Jaime A.\} and Bender, \{Chad F.\} and \{Marta Bernab{\`o}\}, Lia and Blake, \{Cullen H.\} and Cochran, \{William D.\} and Diddams, \{Scott A.\} and Samuel Halverson and Te Han and Fred Hearty and Logsdon, \{Sarah E.\} and Suvrath Mahadevan and Michael McElwain and Andrew Monson and Paul Robertson and Ojha, \{Devendra K.\} and Arpita Roy and Christian Schwab and Gudmundur Stefansson and Jason Wright",

note = "{\textcopyright} 2025. The Author(s). Published by the American Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2025",

month = mar,

day = "3",

doi = "10.3847/1538-3881/ada7ea",

language = "English",

volume = "169",

pages = "187--200",

journal = "The Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "3",

}

Reji, V, Kanodia, S, Ninan, JP, Cañas, CI, Libby-Roberts, J, Lin, ASJ, Gupta, AF, Sewaby, TN, Larsen, A, Kobulnicky, HA, Choi, PI, Evans, N, Santomenna, S, Winnick, I, Yu, L, Alvarado-Montes, JA, Bender, CF, Marta Bernabò, L, Blake, CH, Cochran, WD, Diddams, SA, Halverson, S, Han, T, Hearty, F, Logsdon, SE, Mahadevan, S, McElwain, M, Monson, A, Robertson, P, Ojha, DK, Roy, A, Schwab, C, Stefansson, G & Wright, J 2025, 'Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf', The Astronomical Journal, vol. 169, no. 3, 187, pp. 187-200. https://doi.org/10.3847/1538-3881/ada7ea

TY - JOUR

T1 - Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

AU - Reji, Varghese

AU - Kanodia, Shubham

AU - Ninan, Joe P.

AU - Cañas, Caleb I.

AU - Libby-Roberts, Jessica

AU - Lin, Andrea S. J.

AU - Gupta, Arvind F

AU - Sewaby, Tera N.

AU - Larsen, Alexander

AU - Kobulnicky, Henry A.

AU - Choi, Philip I.

AU - Evans, Nez

AU - Santomenna, Sage

AU - Winnick, Isabelle

AU - Yu, Larry

AU - Alvarado-Montes, Jaime A.

AU - Bender, Chad F.

AU - Marta Bernabò, Lia

AU - Blake, Cullen H.

AU - Cochran, William D.

AU - Diddams, Scott A.

AU - Halverson, Samuel

AU - Han, Te

AU - Hearty, Fred

AU - Logsdon, Sarah E.

AU - Mahadevan, Suvrath

AU - McElwain, Michael

AU - Monson, Andrew

AU - Robertson, Paul

AU - Ojha, Devendra K.

AU - Roy, Arpita

AU - Schwab, Christian

AU - Stefansson, Gudmundur

AU - Wright, Jason

N1 - © 2025. The Author(s). Published by the American Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2025/3/3

Y1 - 2025/3/3

N2 - We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets (R ≳ 8 R⊕) through the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite, and characterized with ground-based transits from Red Buttes Observatory, the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder on the 10 m Hobby Eberly Telescope and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of 124 ± 24 M⊕ (0.39 ± 0.07 MJ) and 10.4 ± 0.7 R⊕ (0.92 ± 0.06 RJ), respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] = 0.47 ± 0.16 dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of ~5″ (1110 au) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems.

AB - We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets (R ≳ 8 R⊕) through the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite, and characterized with ground-based transits from Red Buttes Observatory, the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder on the 10 m Hobby Eberly Telescope and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of 124 ± 24 M⊕ (0.39 ± 0.07 MJ) and 10.4 ± 0.7 R⊕ (0.92 ± 0.06 RJ), respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] = 0.47 ± 0.16 dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of ~5″ (1110 au) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems.

KW - Extrasolar gaseous giant planets

KW - M dwarf stars

KW - Radial velocity

KW - Transit

UR - https://www.scopus.com/pages/publications/85219569072

U2 - 10.3847/1538-3881/ada7ea

DO - 10.3847/1538-3881/ada7ea

M3 - Article

SN - 0004-6256

VL - 169

SP - 187

EP - 200

JO - The Astronomical Journal

JF - The Astronomical Journal

IS - 3

M1 - 187

ER -

Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf

Abstract

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Keywords

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