The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES

Daisy A. Turner; Yoshi Nike Emilia Eschen; Felipe Murgas; Annelies Mortier; Thomas G Wilson; Jorge Fernández Fernández; Nicole Gromek; Giuseppe Morello; Hugo M. Tabernero; Jo Ann Egger; Shreyas Vissapragada; José A. Caballero; Stefan Dreizler; Alix Violet Freckelton; Artie P. Hatzes; Ben Scott Lakeland; Evangelos Nagel; Luca Naponiello; Siegfried Vanaverbeke; Alexander Venner; María Rosa Zapatero Osorio; Pedro J. Amado; Víctor J. S. Béjar; Aldo Stefano Bonomo; Lars A. Buchhave; Andrew Collier Cameron; Ilaria Carleo; Priyanka Chaturvedi; Ryan Cloutier; Mario Damasso; Mangesh Daspute; Shishir Dholakia; Sjoerd Dufoer; Xavier Dumusque; Aldo Fabricio Martinez Fiorenzano; Adriano Ghedina; Avet Harutyunyan; Enrique Herrero; Ancy Anna John; Jorge Lillo-Box; Nicolas Lodieu; Mercedes López-Morales; Luca Malavolta; Luigi Mancini; Giacomo Mantovan; David Montes; Juan Carlos Morales; Belinda Nicholson; Jaume Orell-Miquel; Larissa Palethorpe; Enric Palle; Andreas Quirrenbach; Sabine Reffert; Ansgar Reiners; Ignasi Ribas; Ken Rice; André M. Silva; Alessandro Sozzetti; Manu Stalport; Lev Tal-Or; Trifon Trifonov; Stéphane Udry; Mathias Zechmeister

doi:10.1093/mnras/staf1703

The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES

Daisy A. Turner^*, Yoshi Nike Emilia Eschen, Felipe Murgas, Annelies Mortier, Thomas G Wilson, Jorge Fernández Fernández, Nicole Gromek, Giuseppe Morello, Hugo M. Tabernero, Jo Ann Egger, Shreyas Vissapragada, José A. Caballero, Stefan Dreizler, Alix Violet Freckelton, Artie P. Hatzes, Ben Scott Lakeland, Evangelos Nagel, Luca Naponiello, Siegfried Vanaverbeke, Alexander VennerMaría Rosa Zapatero Osorio, Pedro J. Amado, Víctor J. S. Béjar, Aldo Stefano Bonomo, Lars A. Buchhave, Andrew Collier Cameron, Ilaria Carleo, Priyanka Chaturvedi, Ryan Cloutier, Mario Damasso, Mangesh Daspute, Shishir Dholakia, Sjoerd Dufoer, Xavier Dumusque, Aldo Fabricio Martinez Fiorenzano, Adriano Ghedina, Avet Harutyunyan, Enrique Herrero, Ancy Anna John, Jorge Lillo-Box, Nicolas Lodieu, Mercedes López-Morales, Luca Malavolta, Luigi Mancini, Giacomo Mantovan, David Montes, Juan Carlos Morales, Belinda Nicholson, Jaume Orell-Miquel, Larissa Palethorpe, Enric Palle, Andreas Quirrenbach, Sabine Reffert, Ansgar Reiners, Ignasi Ribas, Ken Rice, André M. Silva, Alessandro Sozzetti, Manu Stalport, Lev Tal-Or, Trifon Trifonov, Stéphane Udry, Mathias Zechmeister

^*Corresponding author for this work

Physics and Astronomy

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Abstract

Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar System. M dwarfs are promising hosts since the planetary signals are within our current detection capabilities. Gliese 12 b is a Venus-sized temperate planet orbiting a quiet M dwarf. We present here the first precise mass measurement of this small exoplanet. We performed a detailed analysis using HARPS-N, ESPRESSO, and CARMENES radial velocities, along with new and archival TESS, CHEOPS, and MuSCAT2/3 photometry data. From fitting the available data, we find that the planet has a radius of R_p = 0.93 ± 0.06 R_⊕ and a mass of M_p = ^+0.29_-0.30 M_⊕ (a 3.2σ measurement of the semi-amplitude K=0.67 ± 21 ms^-1, and is on an orbit with a period of 12.761418^+0.000060_-0.000055d. A variety of techniques were utilised to attenuate stellar activity signals. Gliese 12 b has an equilibrium temperature of T_eq=317 ± 8 K, assuming an albedo of zero, and a density consistent with that of Earth and Venus (ρ_p=6.4 ± 2.4g cm^-3. We find that Gliese 12 b has a predominantly rocky interior and simulations indicate that it is unlikely to have retained any of its primordial gaseous envelope. The bulk properties of Gliese 12 b place it in an extremely sparsely populated region of both mass--radius and density-T_eq parameter space, making it a prime target for follow-up observations, including Lyman-α studies.

Original language	English
Article number	staf1703
Journal	Monthly Notices of the Royal Astronomical Society
Early online date	7 Oct 2025
DOIs	https://doi.org/10.1093/mnras/staf1703
Publication status	E-pub ahead of print - 7 Oct 2025

Bibliographical note

Preprint:
https://doi.org/10.48550/arXiv.2506.20564
25 pages, 14 figures; accepted for publication in MNRAS

Keywords

astro-ph.EP

Access to Document

10.1093/mnras/staf1703Licence: Creative Commons: Attribution (CC BY)

TurnerD2025Mass_AAMonlineAccepted author manuscript, 4.69 MBLicence: Creative Commons: Attribution (CC BY)

Cite this

Turner, D. A., Eschen, Y. N. E., Murgas, F., Mortier, A., Wilson, T. G., Fernández, J. F., Gromek, N., Morello, G., Tabernero, H. M., Egger, J. A., Vissapragada, S., Caballero, J. A., Dreizler, S., Freckelton, A. V., Hatzes, A. P., Lakeland, B. S., Nagel, E., Naponiello, L., Vanaverbeke, S., ... Zechmeister, M. (2025). The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES. Monthly Notices of the Royal Astronomical Society, Article staf1703. Advance online publication. https://doi.org/10.1093/mnras/staf1703

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title = "The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES",

abstract = "Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar System. M dwarfs are promising hosts since the planetary signals are within our current detection capabilities. Gliese 12 b is a Venus-sized temperate planet orbiting a quiet M dwarf. We present here the first precise mass measurement of this small exoplanet. We performed a detailed analysis using HARPS-N, ESPRESSO, and CARMENES radial velocities, along with new and archival TESS, CHEOPS, and MuSCAT2/3 photometry data. From fitting the available data, we find that the planet has a radius of Rp = 0.93 ± 0.06 R⊕ and a mass of Mp = +0.29-0.30 M⊕ (a 3.2σ measurement of the semi-amplitude K=0.67 ± 21 ms-1, and is on an orbit with a period of 12.761418+0.000060-0.000055 d. A variety of techniques were utilised to attenuate stellar activity signals. Gliese 12 b has an equilibrium temperature of Teq=317 ± 8 K, assuming an albedo of zero, and a density consistent with that of Earth and Venus (ρp=6.4 ± 2.4g cm-3. We find that Gliese 12 b has a predominantly rocky interior and simulations indicate that it is unlikely to have retained any of its primordial gaseous envelope. The bulk properties of Gliese 12 b place it in an extremely sparsely populated region of both mass--radius and density-Teq parameter space, making it a prime target for follow-up observations, including Lyman-α studies. ",

keywords = "astro-ph.EP",

author = "Turner, \{Daisy A.\} and Eschen, \{Yoshi Nike Emilia\} and Felipe Murgas and Annelies Mortier and Wilson, \{Thomas G\} and Fern{\'a}ndez, \{Jorge Fern{\'a}ndez\} and Nicole Gromek and Giuseppe Morello and Tabernero, \{Hugo M.\} and Egger, \{Jo Ann\} and Shreyas Vissapragada and Caballero, \{Jos{\'e} A.\} and Stefan Dreizler and Freckelton, \{Alix Violet\} and Hatzes, \{Artie P.\} and Lakeland, \{Ben Scott\} and Evangelos Nagel and Luca Naponiello and Siegfried Vanaverbeke and Alexander Venner and Osorio, \{Mar{\'i}a Rosa Zapatero\} and Amado, \{Pedro J.\} and B{\'e}jar, \{V{\'i}ctor J. S.\} and Bonomo, \{Aldo Stefano\} and Buchhave, \{Lars A.\} and Cameron, \{Andrew Collier\} and Ilaria Carleo and Priyanka Chaturvedi and Ryan Cloutier and Mario Damasso and Mangesh Daspute and Shishir Dholakia and Sjoerd Dufoer and Xavier Dumusque and Fiorenzano, \{Aldo Fabricio Martinez\} and Adriano Ghedina and Avet Harutyunyan and Enrique Herrero and John, \{Ancy Anna\} and Jorge Lillo-Box and Nicolas Lodieu and Mercedes L{\'o}pez-Morales and Luca Malavolta and Luigi Mancini and Giacomo Mantovan and David Montes and Morales, \{Juan Carlos\} and Belinda Nicholson and Jaume Orell-Miquel and Larissa Palethorpe and Enric Palle and Andreas Quirrenbach and Sabine Reffert and Ansgar Reiners and Ignasi Ribas and Ken Rice and Silva, \{Andr{\'e} M.\} and Alessandro Sozzetti and Manu Stalport and Lev Tal-Or and Trifon Trifonov and St{\'e}phane Udry and Mathias Zechmeister",

note = "Preprint: https://doi.org/10.48550/arXiv.2506.20564 25 pages, 14 figures; accepted for publication in MNRAS",

year = "2025",

month = oct,

day = "7",

doi = "10.1093/mnras/staf1703",

language = "English",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "SIPRI/Oxford University Press",

}

Turner, DA, Eschen, YNE, Murgas, F, Mortier, A, Wilson, TG, Fernández, JF, Gromek, N, Morello, G, Tabernero, HM, Egger, JA, Vissapragada, S, Caballero, JA, Dreizler, S, Freckelton, AV, Hatzes, AP, Lakeland, BS, Nagel, E, Naponiello, L, Vanaverbeke, S, Venner, A, Osorio, MRZ, Amado, PJ, Béjar, VJS, Bonomo, AS, Buchhave, LA, Cameron, AC, Carleo, I, Chaturvedi, P, Cloutier, R, Damasso, M, Daspute, M, Dholakia, S, Dufoer, S, Dumusque, X, Fiorenzano, AFM, Ghedina, A, Harutyunyan, A, Herrero, E, John, AA, Lillo-Box, J, Lodieu, N, López-Morales, M, Malavolta, L, Mancini, L, Mantovan, G, Montes, D, Morales, JC, Nicholson, B, Orell-Miquel, J, Palethorpe, L, Palle, E, Quirrenbach, A, Reffert, S, Reiners, A, Ribas, I, Rice, K, Silva, AM, Sozzetti, A, Stalport, M, Tal-Or, L, Trifonov, T, Udry, S & Zechmeister, M 2025, 'The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES', Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/staf1703

TY - JOUR

T1 - The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES

AU - Turner, Daisy A.

AU - Eschen, Yoshi Nike Emilia

AU - Murgas, Felipe

AU - Mortier, Annelies

AU - Wilson, Thomas G

AU - Fernández, Jorge Fernández

AU - Gromek, Nicole

AU - Morello, Giuseppe

AU - Tabernero, Hugo M.

AU - Egger, Jo Ann

AU - Vissapragada, Shreyas

AU - Caballero, José A.

AU - Dreizler, Stefan

AU - Freckelton, Alix Violet

AU - Hatzes, Artie P.

AU - Lakeland, Ben Scott

AU - Nagel, Evangelos

AU - Naponiello, Luca

AU - Vanaverbeke, Siegfried

AU - Venner, Alexander

AU - Osorio, María Rosa Zapatero

AU - Amado, Pedro J.

AU - Béjar, Víctor J. S.

AU - Bonomo, Aldo Stefano

AU - Buchhave, Lars A.

AU - Cameron, Andrew Collier

AU - Carleo, Ilaria

AU - Chaturvedi, Priyanka

AU - Cloutier, Ryan

AU - Damasso, Mario

AU - Daspute, Mangesh

AU - Dholakia, Shishir

AU - Dufoer, Sjoerd

AU - Dumusque, Xavier

AU - Fiorenzano, Aldo Fabricio Martinez

AU - Ghedina, Adriano

AU - Harutyunyan, Avet

AU - Herrero, Enrique

AU - John, Ancy Anna

AU - Lillo-Box, Jorge

AU - Lodieu, Nicolas

AU - López-Morales, Mercedes

AU - Malavolta, Luca

AU - Mancini, Luigi

AU - Mantovan, Giacomo

AU - Montes, David

AU - Morales, Juan Carlos

AU - Nicholson, Belinda

AU - Orell-Miquel, Jaume

AU - Palethorpe, Larissa

AU - Palle, Enric

AU - Quirrenbach, Andreas

AU - Reffert, Sabine

AU - Reiners, Ansgar

AU - Ribas, Ignasi

AU - Rice, Ken

AU - Silva, André M.

AU - Sozzetti, Alessandro

AU - Stalport, Manu

AU - Tal-Or, Lev

AU - Trifonov, Trifon

AU - Udry, Stéphane

AU - Zechmeister, Mathias

N1 - Preprint: https://doi.org/10.48550/arXiv.2506.20564 25 pages, 14 figures; accepted for publication in MNRAS

PY - 2025/10/7

Y1 - 2025/10/7

N2 - Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar System. M dwarfs are promising hosts since the planetary signals are within our current detection capabilities. Gliese 12 b is a Venus-sized temperate planet orbiting a quiet M dwarf. We present here the first precise mass measurement of this small exoplanet. We performed a detailed analysis using HARPS-N, ESPRESSO, and CARMENES radial velocities, along with new and archival TESS, CHEOPS, and MuSCAT2/3 photometry data. From fitting the available data, we find that the planet has a radius of Rp = 0.93 ± 0.06 R⊕ and a mass of Mp = +0.29-0.30 M⊕ (a 3.2σ measurement of the semi-amplitude K=0.67 ± 21 ms-1, and is on an orbit with a period of 12.761418+0.000060-0.000055 d. A variety of techniques were utilised to attenuate stellar activity signals. Gliese 12 b has an equilibrium temperature of Teq=317 ± 8 K, assuming an albedo of zero, and a density consistent with that of Earth and Venus (ρp=6.4 ± 2.4g cm-3. We find that Gliese 12 b has a predominantly rocky interior and simulations indicate that it is unlikely to have retained any of its primordial gaseous envelope. The bulk properties of Gliese 12 b place it in an extremely sparsely populated region of both mass--radius and density-Teq parameter space, making it a prime target for follow-up observations, including Lyman-α studies.

AB - Small temperate planets are prime targets for exoplanet studies due to their possible similarities with the rocky planets in the Solar System. M dwarfs are promising hosts since the planetary signals are within our current detection capabilities. Gliese 12 b is a Venus-sized temperate planet orbiting a quiet M dwarf. We present here the first precise mass measurement of this small exoplanet. We performed a detailed analysis using HARPS-N, ESPRESSO, and CARMENES radial velocities, along with new and archival TESS, CHEOPS, and MuSCAT2/3 photometry data. From fitting the available data, we find that the planet has a radius of Rp = 0.93 ± 0.06 R⊕ and a mass of Mp = +0.29-0.30 M⊕ (a 3.2σ measurement of the semi-amplitude K=0.67 ± 21 ms-1, and is on an orbit with a period of 12.761418+0.000060-0.000055 d. A variety of techniques were utilised to attenuate stellar activity signals. Gliese 12 b has an equilibrium temperature of Teq=317 ± 8 K, assuming an albedo of zero, and a density consistent with that of Earth and Venus (ρp=6.4 ± 2.4g cm-3. We find that Gliese 12 b has a predominantly rocky interior and simulations indicate that it is unlikely to have retained any of its primordial gaseous envelope. The bulk properties of Gliese 12 b place it in an extremely sparsely populated region of both mass--radius and density-Teq parameter space, making it a prime target for follow-up observations, including Lyman-α studies.

KW - astro-ph.EP

U2 - 10.1093/mnras/staf1703

DO - 10.1093/mnras/staf1703

M3 - Article

SN - 0035-8711

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

M1 - staf1703

ER -

The mass of the exo-Venus Gliese 12 b, as revealed by HARPS-N, ESPRESSO, and CARMENES

Abstract

Bibliographical note

Keywords

Access to Document

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Cite this