A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654

Fei Dai; Kevin C. Schlaufman; Henrique Reggiani; Luke Bouma; Andrew W. Howard; Ashley Chontos; Daria Pidhorodetska; Judah Van Zandt; Joseph M. Akana Murphy; Ryan A. Rubenzahl; Alex S. Polanski; Jack Lubin; Corey Beard; Steven Giacalone; Rae Holcomb; Natalie M. Batalha; Ian Crossfield; Courtney Dressing; Benjamin Fulton; Daniel Huber; Howard Isaacson; Stephen R. Kane; Erik A. Petigura; Paul Robertson; Lauren M. Weiss; Alexander A. Belinski; Andrew W. Boyle; Christopher J. Burke; Amadeo Castro-González; David R. Ciardi; Tansu Daylan; Akihiko Fukui; Holden Gill; Natalia M. Guerrero; Coel Hellier; Steve B. Howell; Jorge Lillo-Box; Felipe Murgas; Norio Narita; Enric Pallé; David R. Rodriguez; Arjun B. Savel; Avi Shporer; Keivan G. Stassun; Stephanie Striegel; Douglas A. Caldwell; Jon M. Jenkins; George R. Ricker; Sara Seager; Roland Vanderspek; Joshua N. Winn

doi:10.3847/1538-3881/acdee8

A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654

Fei Dai, Kevin C. Schlaufman, Henrique Reggiani, Luke Bouma, Andrew W. Howard, Ashley Chontos, Daria Pidhorodetska, Judah Van Zandt, Joseph M. Akana Murphy, Ryan A. Rubenzahl, Alex S. Polanski, Jack Lubin, Corey Beard, Steven Giacalone, Rae Holcomb, Natalie M. Batalha, Ian Crossfield, Courtney Dressing, Benjamin Fulton, Daniel HuberHoward Isaacson, Stephen R. Kane, Erik A. Petigura, Paul Robertson, Lauren M. Weiss, Alexander A. Belinski, Andrew W. Boyle, Christopher J. Burke, Amadeo Castro-González, David R. Ciardi, Tansu Daylan, Akihiko Fukui, Holden Gill, Natalia M. Guerrero, Coel Hellier, Steve B. Howell, Jorge Lillo-Box, Felipe Murgas, Norio Narita, Enric Pallé, David R. Rodriguez, Arjun B. Savel, Avi Shporer, Keivan G. Stassun, Stephanie Striegel, Douglas A. Caldwell, Jon M. Jenkins, George R. Ricker, Sara Seager, Roland Vanderspek, Joshua N. Winn

Astrophysical Sciences

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Abstract

We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R _⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has T eff = 4174 − 42 + 34 K, log g = 4.62 − 0.03 + 0.02 , [Fe/H] = − 0.58 ± 0.18, M _* = 0.57 ± 0.02 M _⊙, and R _* = 0.62 ± 0.01 R _⊙. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M _p = 9.2 ± 2.1 M _⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ∼1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M _⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.

Original language	English (US)
Article number	49
Journal	Astronomical Journal
Volume	166
Issue number	2
DOIs	https://doi.org/10.3847/1538-3881/acdee8
State	Published - Aug 1 2023

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-3881/acdee8

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Dai, F., Schlaufman, K. C., Reggiani, H., Bouma, L., Howard, A. W., Chontos, A., Pidhorodetska, D., Van Zandt, J., Akana Murphy, J. M., Rubenzahl, R. A., Polanski, A. S., Lubin, J., Beard, C., Giacalone, S., Holcomb, R., Batalha, N. M., Crossfield, I., Dressing, C., Fulton, B., ... Winn, J. N. (2023). A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654. Astronomical Journal, 166(2), Article 49. https://doi.org/10.3847/1538-3881/acdee8

@article{5c516e5515754f8dbff8216d4fb57451,

title = "A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654",

abstract = "We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R ⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has T eff = 4174 − 42 + 34 K, log g = 4.62 − 0.03 + 0.02 , [Fe/H] = − 0.58 ± 0.18, M * = 0.57 ± 0.02 M ⊙, and R * = 0.62 ± 0.01 R ⊙. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M p = 9.2 ± 2.1 M ⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ∼1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M ⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.",

author = "Fei Dai and Schlaufman, {Kevin C.} and Henrique Reggiani and Luke Bouma and Howard, {Andrew W.} and Ashley Chontos and Daria Pidhorodetska and {Van Zandt}, Judah and {Akana Murphy}, {Joseph M.} and Rubenzahl, {Ryan A.} and Polanski, {Alex S.} and Jack Lubin and Corey Beard and Steven Giacalone and Rae Holcomb and Batalha, {Natalie M.} and Ian Crossfield and Courtney Dressing and Benjamin Fulton and Daniel Huber and Howard Isaacson and Kane, {Stephen R.} and Petigura, {Erik A.} and Paul Robertson and Weiss, {Lauren M.} and Belinski, {Alexander A.} and Boyle, {Andrew W.} and Burke, {Christopher J.} and Amadeo Castro-Gonz{\'a}lez and Ciardi, {David R.} and Tansu Daylan and Akihiko Fukui and Holden Gill and Guerrero, {Natalia M.} and Coel Hellier and Howell, {Steve B.} and Jorge Lillo-Box and Felipe Murgas and Norio Narita and Enric Pall{\'e} and Rodriguez, {David R.} and Savel, {Arjun B.} and Avi Shporer and Stassun, {Keivan G.} and Stephanie Striegel and Caldwell, {Douglas A.} and Jenkins, {Jon M.} and Ricker, {George R.} and Sara Seager and Roland Vanderspek and Winn, {Joshua N.}",

note = "Funding Information: J.M.A.M. is supported by the National Science Foundation (NSF) Graduate Research Fellowship Program under grant No. DGE-1842400. J.M.A.M. acknowledges the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining grant No. 1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. Funding Information: This material is based on work supported by the TESS General Investigator program under NASA grant 80NSSC20K0059. Funding Information: D.R.C. acknowledges partial support from NASA grant 18-2XRP18_2-0007. Funding Information: The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Funding Information: Some of the observations in this paper made use of the High-Resolution Imaging instrument Alopeke and were obtained under Gemini LLP Proposal Number GN/S-2021A-LP-105. Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Alopeke was mounted on the Gemini North telescope of the international Gemini Observatory, a program of NSF's NOIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigaci{\'o}n y Desarrollo (Chile), Ministerio de Ciencia, Tecnolog{\'i}a e Innovaci{\'o}n (Argentina), Minist{\'e}rio da Ci{\^e}ncia, Tecnologia, Inova{\c c}{\~o}es e Comunica{\c c}{\'o}es (Brazil), and the Korea Astronomy and Space Science Institute (Republic of Korea). Funding Information: This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos S{\'a}nchez, operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. This work is partly financed by the Spanish Ministry of Economics and Competitiveness through grants PGC2018-098153-B-C31. Funding Information: A.C.-G. is funded by the Spanish Ministry of Science through MCIN/AEI/10.13039/501100011033 grant PID2019-107061GB-C61. Funding Information: J.L.-B. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovaci (MCIN/AEI/ 10.13039/501100011033) and the European Union NextGeneration EU/PRTR under the Ramon y Cajal program with code RYC2021-031640-I. Based on observations collected at the Centro Astronomico Hispano en Andalucia (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). Funding Information: Funding for the TESS mission is provided by NASA's Science Mission Directorate. Funding Information: This work is partly supported by JSPS KAKENHI grant No. JP18H05439 and JST CREST grant No. JPMJCR1761. This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos S{\'a}nchez, operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. Funding Information: D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC21K0652), and the Australian Research Council (FT200100871). Funding Information: A.A.B. acknowledges the support of the Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780 (N13.1902.21.0039). Publisher Copyright: {\textcopyright} 2023. The Author(s). Published by the American Astronomical Society.",

year = "2023",

month = aug,

day = "1",

doi = "10.3847/1538-3881/acdee8",

language = "English (US)",

volume = "166",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Dai, F, Schlaufman, KC, Reggiani, H, Bouma, L, Howard, AW, Chontos, A, Pidhorodetska, D, Van Zandt, J, Akana Murphy, JM, Rubenzahl, RA, Polanski, AS, Lubin, J, Beard, C, Giacalone, S, Holcomb, R, Batalha, NM, Crossfield, I, Dressing, C, Fulton, B, Huber, D, Isaacson, H, Kane, SR, Petigura, EA, Robertson, P, Weiss, LM, Belinski, AA, Boyle, AW, Burke, CJ, Castro-González, A, Ciardi, DR, Daylan, T, Fukui, A, Gill, H, Guerrero, NM, Hellier, C, Howell, SB, Lillo-Box, J, Murgas, F, Narita, N, Pallé, E, Rodriguez, DR, Savel, AB, Shporer, A, Stassun, KG, Striegel, S, Caldwell, DA, Jenkins, JM, Ricker, GR, Seager, S, Vanderspek, R & Winn, JN 2023, 'A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654', Astronomical Journal, vol. 166, no. 2, 49. https://doi.org/10.3847/1538-3881/acdee8

TY - JOUR

T1 - A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654

AU - Dai, Fei

AU - Schlaufman, Kevin C.

AU - Reggiani, Henrique

AU - Bouma, Luke

AU - Howard, Andrew W.

AU - Chontos, Ashley

AU - Pidhorodetska, Daria

AU - Van Zandt, Judah

AU - Akana Murphy, Joseph M.

AU - Rubenzahl, Ryan A.

AU - Polanski, Alex S.

AU - Lubin, Jack

AU - Beard, Corey

AU - Giacalone, Steven

AU - Holcomb, Rae

AU - Batalha, Natalie M.

AU - Crossfield, Ian

AU - Dressing, Courtney

AU - Fulton, Benjamin

AU - Huber, Daniel

AU - Isaacson, Howard

AU - Kane, Stephen R.

AU - Petigura, Erik A.

AU - Robertson, Paul

AU - Weiss, Lauren M.

AU - Belinski, Alexander A.

AU - Boyle, Andrew W.

AU - Burke, Christopher J.

AU - Castro-González, Amadeo

AU - Ciardi, David R.

AU - Daylan, Tansu

AU - Fukui, Akihiko

AU - Gill, Holden

AU - Guerrero, Natalia M.

AU - Hellier, Coel

AU - Howell, Steve B.

AU - Lillo-Box, Jorge

AU - Murgas, Felipe

AU - Narita, Norio

AU - Pallé, Enric

AU - Rodriguez, David R.

AU - Savel, Arjun B.

AU - Shporer, Avi

AU - Stassun, Keivan G.

AU - Striegel, Stephanie

AU - Caldwell, Douglas A.

AU - Jenkins, Jon M.

AU - Ricker, George R.

AU - Seager, Sara

AU - Vanderspek, Roland

AU - Winn, Joshua N.

N1 - Funding Information: J.M.A.M. is supported by the National Science Foundation (NSF) Graduate Research Fellowship Program under grant No. DGE-1842400. J.M.A.M. acknowledges the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining grant No. 1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. Funding Information: This material is based on work supported by the TESS General Investigator program under NASA grant 80NSSC20K0059. Funding Information: D.R.C. acknowledges partial support from NASA grant 18-2XRP18_2-0007. Funding Information: The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Funding Information: Some of the observations in this paper made use of the High-Resolution Imaging instrument Alopeke and were obtained under Gemini LLP Proposal Number GN/S-2021A-LP-105. Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Alopeke was mounted on the Gemini North telescope of the international Gemini Observatory, a program of NSF's NOIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicaçóes (Brazil), and the Korea Astronomy and Space Science Institute (Republic of Korea). Funding Information: This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sánchez, operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. This work is partly financed by the Spanish Ministry of Economics and Competitiveness through grants PGC2018-098153-B-C31. Funding Information: A.C.-G. is funded by the Spanish Ministry of Science through MCIN/AEI/10.13039/501100011033 grant PID2019-107061GB-C61. Funding Information: J.L.-B. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovaci (MCIN/AEI/ 10.13039/501100011033) and the European Union NextGeneration EU/PRTR under the Ramon y Cajal program with code RYC2021-031640-I. Based on observations collected at the Centro Astronomico Hispano en Andalucia (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). Funding Information: Funding for the TESS mission is provided by NASA's Science Mission Directorate. Funding Information: This work is partly supported by JSPS KAKENHI grant No. JP18H05439 and JST CREST grant No. JPMJCR1761. This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sánchez, operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. Funding Information: D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC21K0652), and the Australian Research Council (FT200100871). Funding Information: A.A.B. acknowledges the support of the Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780 (N13.1902.21.0039). Publisher Copyright: © 2023. The Author(s). Published by the American Astronomical Society.

PY - 2023/8/1

Y1 - 2023/8/1

N2 - We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R ⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has T eff = 4174 − 42 + 34 K, log g = 4.62 − 0.03 + 0.02 , [Fe/H] = − 0.58 ± 0.18, M * = 0.57 ± 0.02 M ⊙, and R * = 0.62 ± 0.01 R ⊙. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M p = 9.2 ± 2.1 M ⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ∼1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M ⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.

AB - We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R ⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has T eff = 4174 − 42 + 34 K, log g = 4.62 − 0.03 + 0.02 , [Fe/H] = − 0.58 ± 0.18, M * = 0.57 ± 0.02 M ⊙, and R * = 0.62 ± 0.01 R ⊙. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M p = 9.2 ± 2.1 M ⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ∼1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M ⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.

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UR - http://www.scopus.com/inward/citedby.url?scp=85165200672&partnerID=8YFLogxK

U2 - 10.3847/1538-3881/acdee8

DO - 10.3847/1538-3881/acdee8

M3 - Article

AN - SCOPUS:85165200672

SN - 0004-6256

VL - 166

JO - Astronomical Journal

JF - Astronomical Journal

IS - 2

M1 - 49

ER -

A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654

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