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 = "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 = "American Astronomical Society",

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.

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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