An Earth-sized Planet around an M5 Dwarf Star at 22 pc

Hirano, Teruyuki; Dai, Fei; Livingston, John H.; Grziwa, S.; Lam, K. W. F.; Kasagi, Yui; Narita, Norio; Ishikawa, Hiroyuki; Miyakawa, Kohei; Serrano, L. M.; Matsumoto, Yuji; Kokubo, Eiichiro; Kimura, Tadahiro; Ikoma, Masahiro; Winn, Joshua N.; Wisniewski, John P.; Harakawa, Hiroki; Teng, Huan-Yu; Cochran, William D.; Fukui, A.; Guenther, E. W.; Hori, Yasunori; Ikuta, Kazumasa; Kawauchi, Kiyoe; Knudstrup, Emil; Korth, J.; Kotani, Takayuki; Krishnamurthy, Vigneshwaran; Kudo, Tomoyuki; Kurokawa, Takashi; Kuzuhara, Masayuki; Luque, R.; Mori, M.; Nishikawa, Jun; Omiya, Masashi; Orell-Miquel, J.; Πάλλη, Ε.; Persson, C. M.; Redfield, Seth; Serabyn, Eugene; Smith, A. M. S.; Takahashi, Aoi; Takuya, Takarada,; Ueda, Akitoshi; Eylen, Vincent Van; Vievard, Sébastien; Tamura, Motohide; Sato, Bun’ei

doi:10.3847/1538-3881/acb7e1

Cited by 3 publications

(1 citation statement)

References 95 publications

(100 reference statements)

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“…We followed the method developed by Ishikawa et al (2020), which measures the equivalent widths (EWs) of the molecular lines and some atomic lines and compares them with those from theoretical synthetic spectra. We focused on the molecular lines of FeH and the atomic lines of Na, Mg, Ca, Ti, Cr, Mn, Fe, and Sr via the procedures adopted in the previous IRD-SSP papers (see Harakawa et al 2022;Ishikawa et al 2022;Hirano et al 2023 for details). The T eff and [Fe/H] of Gliese 12 were derived to be 3344 ± 44 K and −0.43 ± 0.15 dex, respectively.…”

Section: Stellar Parametersmentioning

confidence: 99%

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy

Kuzuhara,

Fukui,

Livingston

et al. 2024

ApJL

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Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (P orb) of 12.76 days. The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous P orb from TESS data. We confirmed the transit signal and P orb using ground-based photometry with MuSCAT2 and MuSCAT3, and validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host star is inactive, with an X-ray-to-bolometric luminosity ratio of log L X / L bol ≈ − 5.7 . Joint analysis of the light curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R ⊕, a 3σ mass upper limit of 3.9 M ⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric (TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.

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Section: Stellar Parametersmentioning

confidence: 99%

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy

Kuzuhara,

Fukui,

Livingston

et al. 2024

ApJL

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TESS discovery of a super-Earth orbiting the M-dwarf star TOI-1680

Ghachoui¹,

A.²,

Wells³

2023

A&A

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We report the discovery by the TESS mission of a super-Earth on a 4.8-days orbit around an inactive M4.5 dwarf (TOI-1680), validated by ground-based facilities. The host star is located 37.14 pc away, with a radius of 0.2100 ± 0.0064 R⊙, mass of 0.1800 ± 0.0044 M⊙, and an effective temperature of 3211 ±100 K. We validated and characterized the planet using TESS data, ground-based multi-wavelength photometry from TRAPPIST, SPECULOOS, and LCO, as well as high-resolution AO observations from Keck/NIRC2 and Shane. Our analyses have determined the following parameters for the planet: a radius of 1.466−0.049+0.063 R⊕ and an equilibrium temperature of 404 ± 14 K, assuming no albedo and perfect heat redistribution. Assuming a mass based on mass-radius relations, this planet is a promising target for atmospheric characterization with the James Webb Space Telescope (JWST).

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Six-year progress of the InfraRed Doppler (IRD) instrument for the Subaru Telescope

Kuzuhara,

Kotani,

Tamura

et al. 2024

Ground-Based and Airborne Instrumentation for Astronomy X

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The InfraRed Doppler (IRD) instrument is the Subaru telescope's high-resolution (R > 70,000) spectrograph covering wavelengths from 1000 to 1700 nm. A laser frequency comb (LFC) spectrum simultaneously obtained with an object spectrum calibrates wavelength shifts caused by instrumental instability. We originally developed IRD to carry out precision radial velocity (RV) measurements at near-infrared wavelengths. The wide wavelength coverage of IRD, and the large mirror (8.2 m) of the Subaru Telescope enables IRD to provide the best sensitivities to detect a planet orbiting a cool M-type star. The first science operation of IRD was conducted in 2018 and the large strategic blind survey for planets orbiting cool M-type stars started in 2019. Since then, there have been many observations not only for exoplanet category but also for stellar physics, Galaxy, and high-energy astrophysics. IRD spectroscopy allowed for characterizing exoplanet atmospheres by measuring OH emissions, He absorptions, and spin-orbit obliquities. The IRD survey discovered a super-Earth in orbit near a habitable zone of Ross 508. The IRD RV measurements for many systems that host transiting planets, including TOI-2285 b and Gliese 12 b, helped confirm those and determine or constrain their masses. Using REACH, IRD can be combined with the extreme adaptive optics SCExAO, enabling the use of a single-mode fiber and characterizations of faint sub-stellar companions orbiting bright stars. In this proceeding paper, we review and highlight the scientific results achieved by the IRD observations.

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An Earth-sized Planet around an M5 Dwarf Star at 22 pc

Cited by 3 publications

References 95 publications

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy

Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Transmission Spectroscopy

TESS discovery of a super-Earth orbiting the M-dwarf star TOI-1680

Six-year progress of the InfraRed Doppler (IRD) instrument for the Subaru Telescope

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