Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions

Teruyuki Hirano; John H. Livingston; Akihiko Fukui; Norio Narita; Hiroki Harakawa; Hiroyuki Tako Ishikawa; Kohei Miyakawa; Tadahiro Kimura; Akifumi Nakayama; Naho Fujita; Yasunori Hori; Keivan G. Stassun; Allyson Bieryla; Charles Cadieux; David R. Ciardi; Karen A. Collins; Masahiro Ikoma; Andrew Vanderburg; Thomas Barclay; C. E. Brasseur; Jerome P. De Leon; John P. Doty; René Doyon; Emma Esparza-Borges; Gilbert A. Esquerdo; Elise Furlan; Eric Gaidos; Erica J. Gonzales; Klaus Hodapp; Steve B. Howell; Keisuke Isogai; Shane Jacobson; Jon M. Jenkins; Eric L.N. Jensen; Kiyoe Kawauchi; Takayuki Kotani; Tomoyuki Kudo; Seiya Kurita; Takashi Kurokawa; Nobuhiko Kusakabe; Masayuki Kuzuhara; David Lafreniere; David W. Latham; Bob Massey; Mayuko Mori; Felipe Murgas; Jun Nishikawa; Taku Nishiumi; Masashi Omiya; Martin Paegert; Enric Palle; Hannu Parviainen; Samuel N. Quinn; George R. Ricker; Richard P. Schwarz; Sara Seager; Motohide Tamura; Peter Tenenbaum; Yuka Terada; Roland K. Vanderspek; Sébastien Vievard; Noriharu Watanabe; Joshua N. Winn

doi:10.3847/1538-3881/ac0fdc

Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions

Teruyuki Hirano, John H. Livingston, Akihiko Fukui, Norio Narita, Hiroki Harakawa, Hiroyuki Tako Ishikawa, Kohei Miyakawa, Tadahiro Kimura, Akifumi Nakayama, Naho Fujita, Yasunori Hori, Keivan G. Stassun, Allyson Bieryla, Charles Cadieux, David R. Ciardi, Karen A. Collins, Masahiro Ikoma, Andrew Vanderburg, Thomas Barclay, C. E. BrasseurJerome P. De Leon, John P. Doty, René Doyon, Emma Esparza-Borges, Gilbert A. Esquerdo, Elise Furlan, Eric Gaidos, Erica J. Gonzales, Klaus Hodapp, Steve B. Howell, Keisuke Isogai, Shane Jacobson, Jon M. Jenkins, Eric L.N. Jensen, Kiyoe Kawauchi, Takayuki Kotani, Tomoyuki Kudo, Seiya Kurita, Takashi Kurokawa, Nobuhiko Kusakabe, Masayuki Kuzuhara, David Lafreniere, David W. Latham, Bob Massey, Mayuko Mori, Felipe Murgas, Jun Nishikawa, Taku Nishiumi, Masashi Omiya, Martin Paegert, Enric Palle, Hannu Parviainen, Samuel N. Quinn, George R. Ricker, Richard P. Schwarz, Sara Seager, Motohide Tamura, Peter Tenenbaum, Yuka Terada, Roland K. Vanderspek, Sébastien Vievard, Noriharu Watanabe, Joshua N. Winn

Astrophysical Sciences

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Abstract

We present observations of two bright M dwarfs (TOI-1634 and TOI-1685: J = 9.5-9.6) hosting ultra-short-period (USP) planets identified by the TESS mission. The two stars are similar in temperature, mass, and radius (T eff ≈ 3500 K, M ∗ ≈ 0.45-0.46 M o˙, and R ∗ ≈ 0.45-0.46 R o˙), and the planets are both super-Earth size (1.25 R ⊕ < R p < 2.0 R ⊕). For both systems, light curves from ground-based photometry exhibit planetary transits, whose depths are consistent with those from the TESS photometry. We also refine the transit ephemerides based on the ground-based photometry, finding the orbital periods of P = 0.9893436 ± 0.0000020 days and P = 0.6691416 ± 0.0000019 days for TOI-1634b and TOI-1685b, respectively. Through intensive radial velocity (RV) observations using the InfraRed Doppler (IRD) instrument on the Subaru 8.2 m telescope, we confirm the planetary nature of the TOIs and measure their masses: 10.14 ± 0.95 M ⊕ and 3.43 ± 0.93 M ⊕ for TOI-1634b and TOI-1685b, respectively, when the observed RVs are fitted with a single-planet circular-orbit model. Combining those with the planet radii of R p = 1.749 ± 0.079 R ⊕ (TOI-1634b) and 1.459 ± 0.065 R ⊕ (TOI-1685b), we find that both USP planets have mean densities consistent with an Earth-like internal composition, which is typical for small USP planets. TOI-1634b is currently the most massive USP planet in this category, and it resides near the radius valley, which makes it a benchmark planet in the context of discussing the size limit of rocky planet cores as well as testing the formation scenarios for USP planets. Excess scatter in the RV residuals for TOI-1685 suggests the presence of a possible secondary planet or unknown activity/instrumental noise in the RV data, but further observations are required to check those possibilities.

Original language	English (US)
Article number	161
Journal	Astronomical Journal
Volume	162
Issue number	4
DOIs	https://doi.org/10.3847/1538-3881/ac0fdc
State	Published - Oct 2021

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-3881/ac0fdc

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Hirano, T., Livingston, J. H., Fukui, A., Narita, N., Harakawa, H., Ishikawa, H. T., Miyakawa, K., Kimura, T., Nakayama, A., Fujita, N., Hori, Y., Stassun, K. G., Bieryla, A., Cadieux, C., Ciardi, D. R., Collins, K. A., Ikoma, M., Vanderburg, A., Barclay, T., ... Winn, J. N. (2021). Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions. Astronomical Journal, 162(4), Article 161. https://doi.org/10.3847/1538-3881/ac0fdc

@article{b29579c64dc242d9acf413374bf98777,

title = "Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions",

abstract = "We present observations of two bright M dwarfs (TOI-1634 and TOI-1685: J = 9.5-9.6) hosting ultra-short-period (USP) planets identified by the TESS mission. The two stars are similar in temperature, mass, and radius (T eff ≈ 3500 K, M ∗ ≈ 0.45-0.46 M o˙, and R ∗ ≈ 0.45-0.46 R o˙), and the planets are both super-Earth size (1.25 R ⊕ < R p < 2.0 R ⊕). For both systems, light curves from ground-based photometry exhibit planetary transits, whose depths are consistent with those from the TESS photometry. We also refine the transit ephemerides based on the ground-based photometry, finding the orbital periods of P = 0.9893436 ± 0.0000020 days and P = 0.6691416 ± 0.0000019 days for TOI-1634b and TOI-1685b, respectively. Through intensive radial velocity (RV) observations using the InfraRed Doppler (IRD) instrument on the Subaru 8.2 m telescope, we confirm the planetary nature of the TOIs and measure their masses: 10.14 ± 0.95 M ⊕ and 3.43 ± 0.93 M ⊕ for TOI-1634b and TOI-1685b, respectively, when the observed RVs are fitted with a single-planet circular-orbit model. Combining those with the planet radii of R p = 1.749 ± 0.079 R ⊕ (TOI-1634b) and 1.459 ± 0.065 R ⊕ (TOI-1685b), we find that both USP planets have mean densities consistent with an Earth-like internal composition, which is typical for small USP planets. TOI-1634b is currently the most massive USP planet in this category, and it resides near the radius valley, which makes it a benchmark planet in the context of discussing the size limit of rocky planet cores as well as testing the formation scenarios for USP planets. Excess scatter in the RV residuals for TOI-1685 suggests the presence of a possible secondary planet or unknown activity/instrumental noise in the RV data, but further observations are required to check those possibilities.",

author = "Teruyuki Hirano and Livingston, {John H.} and Akihiko Fukui and Norio Narita and Hiroki Harakawa and Ishikawa, {Hiroyuki Tako} and Kohei Miyakawa and Tadahiro Kimura and Akifumi Nakayama and Naho Fujita and Yasunori Hori and Stassun, {Keivan G.} and Allyson Bieryla and Charles Cadieux and Ciardi, {David R.} and Collins, {Karen A.} and Masahiro Ikoma and Andrew Vanderburg and Thomas Barclay and Brasseur, {C. E.} and {De Leon}, {Jerome P.} and Doty, {John P.} and Ren{\'e} Doyon and Emma Esparza-Borges and Esquerdo, {Gilbert A.} and Elise Furlan and Eric Gaidos and Gonzales, {Erica J.} and Klaus Hodapp and Howell, {Steve B.} and Keisuke Isogai and Shane Jacobson and Jenkins, {Jon M.} and Jensen, {Eric L.N.} and Kiyoe Kawauchi and Takayuki Kotani and Tomoyuki Kudo and Seiya Kurita and Takashi Kurokawa and Nobuhiko Kusakabe and Masayuki Kuzuhara and David Lafreniere and Latham, {David W.} and Bob Massey and Mayuko Mori and Felipe Murgas and Jun Nishikawa and Taku Nishiumi and Masashi Omiya and Martin Paegert and Enric Palle and Hannu Parviainen and Quinn, {Samuel N.} and Ricker, {George R.} and Schwarz, {Richard P.} and Sara Seager and Motohide Tamura and Peter Tenenbaum and Yuka Terada and Vanderspek, {Roland K.} and S{\'e}bastien Vievard and Noriharu Watanabe and Winn, {Joshua N.}",

year = "2021",

month = oct,

doi = "10.3847/1538-3881/ac0fdc",

language = "English (US)",

volume = "162",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "IOP Publishing Ltd.",

number = "4",

}

Hirano, T, Livingston, JH, Fukui, A, Narita, N, Harakawa, H, Ishikawa, HT, Miyakawa, K, Kimura, T, Nakayama, A, Fujita, N, Hori, Y, Stassun, KG, Bieryla, A, Cadieux, C, Ciardi, DR, Collins, KA, Ikoma, M, Vanderburg, A, Barclay, T, Brasseur, CE, De Leon, JP, Doty, JP, Doyon, R, Esparza-Borges, E, Esquerdo, GA, Furlan, E, Gaidos, E, Gonzales, EJ, Hodapp, K, Howell, SB, Isogai, K, Jacobson, S, Jenkins, JM, Jensen, ELN, Kawauchi, K, Kotani, T, Kudo, T, Kurita, S, Kurokawa, T, Kusakabe, N, Kuzuhara, M, Lafreniere, D, Latham, DW, Massey, B, Mori, M, Murgas, F, Nishikawa, J, Nishiumi, T, Omiya, M, Paegert, M, Palle, E, Parviainen, H, Quinn, SN, Ricker, GR, Schwarz, RP, Seager, S, Tamura, M, Tenenbaum, P, Terada, Y, Vanderspek, RK, Vievard, S, Watanabe, N & Winn, JN 2021, 'Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions', Astronomical Journal, vol. 162, no. 4, 161. https://doi.org/10.3847/1538-3881/ac0fdc

TY - JOUR

T1 - Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions

AU - Hirano, Teruyuki

AU - Livingston, John H.

AU - Fukui, Akihiko

AU - Narita, Norio

AU - Harakawa, Hiroki

AU - Ishikawa, Hiroyuki Tako

AU - Miyakawa, Kohei

AU - Kimura, Tadahiro

AU - Nakayama, Akifumi

AU - Fujita, Naho

AU - Hori, Yasunori

AU - Stassun, Keivan G.

AU - Bieryla, Allyson

AU - Cadieux, Charles

AU - Ciardi, David R.

AU - Collins, Karen A.

AU - Ikoma, Masahiro

AU - Vanderburg, Andrew

AU - Barclay, Thomas

AU - Brasseur, C. E.

AU - De Leon, Jerome P.

AU - Doty, John P.

AU - Doyon, René

AU - Esparza-Borges, Emma

AU - Esquerdo, Gilbert A.

AU - Furlan, Elise

AU - Gaidos, Eric

AU - Gonzales, Erica J.

AU - Hodapp, Klaus

AU - Howell, Steve B.

AU - Isogai, Keisuke

AU - Jacobson, Shane

AU - Jenkins, Jon M.

AU - Jensen, Eric L.N.

AU - Kawauchi, Kiyoe

AU - Kotani, Takayuki

AU - Kudo, Tomoyuki

AU - Kurita, Seiya

AU - Kurokawa, Takashi

AU - Kusakabe, Nobuhiko

AU - Kuzuhara, Masayuki

AU - Lafreniere, David

AU - Latham, David W.

AU - Massey, Bob

AU - Mori, Mayuko

AU - Murgas, Felipe

AU - Nishikawa, Jun

AU - Nishiumi, Taku

AU - Omiya, Masashi

AU - Paegert, Martin

AU - Palle, Enric

AU - Parviainen, Hannu

AU - Quinn, Samuel N.

AU - Ricker, George R.

AU - Schwarz, Richard P.

AU - Seager, Sara

AU - Tamura, Motohide

AU - Tenenbaum, Peter

AU - Terada, Yuka

AU - Vanderspek, Roland K.

AU - Vievard, Sébastien

AU - Watanabe, Noriharu

AU - Winn, Joshua N.

PY - 2021/10

Y1 - 2021/10

N2 - We present observations of two bright M dwarfs (TOI-1634 and TOI-1685: J = 9.5-9.6) hosting ultra-short-period (USP) planets identified by the TESS mission. The two stars are similar in temperature, mass, and radius (T eff ≈ 3500 K, M ∗ ≈ 0.45-0.46 M o˙, and R ∗ ≈ 0.45-0.46 R o˙), and the planets are both super-Earth size (1.25 R ⊕ < R p < 2.0 R ⊕). For both systems, light curves from ground-based photometry exhibit planetary transits, whose depths are consistent with those from the TESS photometry. We also refine the transit ephemerides based on the ground-based photometry, finding the orbital periods of P = 0.9893436 ± 0.0000020 days and P = 0.6691416 ± 0.0000019 days for TOI-1634b and TOI-1685b, respectively. Through intensive radial velocity (RV) observations using the InfraRed Doppler (IRD) instrument on the Subaru 8.2 m telescope, we confirm the planetary nature of the TOIs and measure their masses: 10.14 ± 0.95 M ⊕ and 3.43 ± 0.93 M ⊕ for TOI-1634b and TOI-1685b, respectively, when the observed RVs are fitted with a single-planet circular-orbit model. Combining those with the planet radii of R p = 1.749 ± 0.079 R ⊕ (TOI-1634b) and 1.459 ± 0.065 R ⊕ (TOI-1685b), we find that both USP planets have mean densities consistent with an Earth-like internal composition, which is typical for small USP planets. TOI-1634b is currently the most massive USP planet in this category, and it resides near the radius valley, which makes it a benchmark planet in the context of discussing the size limit of rocky planet cores as well as testing the formation scenarios for USP planets. Excess scatter in the RV residuals for TOI-1685 suggests the presence of a possible secondary planet or unknown activity/instrumental noise in the RV data, but further observations are required to check those possibilities.

AB - We present observations of two bright M dwarfs (TOI-1634 and TOI-1685: J = 9.5-9.6) hosting ultra-short-period (USP) planets identified by the TESS mission. The two stars are similar in temperature, mass, and radius (T eff ≈ 3500 K, M ∗ ≈ 0.45-0.46 M o˙, and R ∗ ≈ 0.45-0.46 R o˙), and the planets are both super-Earth size (1.25 R ⊕ < R p < 2.0 R ⊕). For both systems, light curves from ground-based photometry exhibit planetary transits, whose depths are consistent with those from the TESS photometry. We also refine the transit ephemerides based on the ground-based photometry, finding the orbital periods of P = 0.9893436 ± 0.0000020 days and P = 0.6691416 ± 0.0000019 days for TOI-1634b and TOI-1685b, respectively. Through intensive radial velocity (RV) observations using the InfraRed Doppler (IRD) instrument on the Subaru 8.2 m telescope, we confirm the planetary nature of the TOIs and measure their masses: 10.14 ± 0.95 M ⊕ and 3.43 ± 0.93 M ⊕ for TOI-1634b and TOI-1685b, respectively, when the observed RVs are fitted with a single-planet circular-orbit model. Combining those with the planet radii of R p = 1.749 ± 0.079 R ⊕ (TOI-1634b) and 1.459 ± 0.065 R ⊕ (TOI-1685b), we find that both USP planets have mean densities consistent with an Earth-like internal composition, which is typical for small USP planets. TOI-1634b is currently the most massive USP planet in this category, and it resides near the radius valley, which makes it a benchmark planet in the context of discussing the size limit of rocky planet cores as well as testing the formation scenarios for USP planets. Excess scatter in the RV residuals for TOI-1685 suggests the presence of a possible secondary planet or unknown activity/instrumental noise in the RV data, but further observations are required to check those possibilities.

UR - http://www.scopus.com/inward/record.url?scp=85116393935&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85116393935&partnerID=8YFLogxK

U2 - 10.3847/1538-3881/ac0fdc

DO - 10.3847/1538-3881/ac0fdc

M3 - Article

AN - SCOPUS:85116393935

SN - 0004-6256

VL - 162

JO - Astronomical Journal

JF - Astronomical Journal

IS - 4

M1 - 161

ER -

Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions

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