CHES: A Space-borne Astrometric Mission for the Detection of Habitable Planets of the Nearby Solar-type Stars

Ji, Jianghui; Li, Haitao; Zhang, Junbo; Fang, Liang; Liu, Dong; Wang, Su; Cao, Yang; Deng, Lei; Li, Baoquan; Xian, Hao; Gao, Xiaodong; Zhang, Ang; Li, Fēi; Liu, Jiacheng; Qi, Zhaoxiang; Sheng, Jin; Liu, Yaning; Chen, Guo; Li, Mingtao; Dong, Yao; consortium, CHES

doi:10.1088/1674-4527/ac77e4

Cited by 22 publications

(14 citation statements)

References 57 publications

(61 reference statements)

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“…Modern astrometric catalogs (i.e., the Gaia Catalogue of Nearby Stars; Smart et al 2021) are at the few tens of microarcseconds level accuracy (Lindegren et al 2021) that is needed to predict likely stellar conjunctions. Ongoing technology developments may may soon be available for an astrometric search for Earth-like exoplanets (Shao et al 2018(Shao et al , 2022Ji et al 2022).…”

Section: Estimating the Occurrence Ratementioning

confidence: 99%

Evolving Morphology of Resolved Stellar Einstein Rings

Turyshev

Toth²

2023

ApJ

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We consider strong gravitational lensing by nearby stars. Using our wave-optical treatment of lensing phenomena, we study Einstein rings that may form around nearby stellar lenses. It is remarkable that these rings are bright and large enough to be detected and resolved by existing instruments. Such lensing events have durations of hours or days, with peak light amplification lasting for several minutes. Many such events may be predicted using the Gaia astrometric catalog. Serendipitous discoveries are also possible. Fortuitous alignments can be used to confirm or discover and study exoplanets. For lenses that have dense stellar regions in their background, these events may occur several time a year, warranting their continuous or recurrent monitoring. Resolved imaging and spectroscopy of the evolving morphology of an Einstein ring offers knowledge about both the lens and the source. The angular size of the Einstein ring amounts to a direct measurement of the lens mass. The changing orientation of the major and minor images of the source offers astrometric information related to the mutual orientation of the objects. The event duration, when the full ring is present, helps to determine the source’s size. The sky position of planetary lensing events constrains the planet’s orbit. Spectroscopy of the ring allows for direct investigations of the source. The frequency and predictability of these events and the wealth of information that can be obtained by imaging motivate observational campaigns using existing facilities and/or construction of new instruments dedicated to the search and study of Einstein rings that are forming around nearby stars. As a specific example, we consider a predicted 2028 lensing of a red giant by α Centauri A and discuss the relevant science campaign.

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Section: Estimating the Occurrence Ratementioning

confidence: 99%

Evolving Morphology of Resolved Stellar Einstein Rings

Turyshev

Toth²

2023

ApJ

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“…The γ Cep system is known as a close binary at a distance of 13.79 pc (Hatzes et al 2003), and it is a candidate target of the CHES mission (Ji et al 2022). The primary star γ Cep A is a planet-hosting bright star of spectral type K1III-IV, with a stellar mass of m 0 = 1.40 ± 0.12 M e (Neuhäuser et al 2007).…”

Section: N-body Fitting Of the Rv Datamentioning

confidence: 99%

Extremely Inclined Orbit of the S-type Planet γ Cep Ab Induced by the Eccentric Kozai–Lidov Mechanism

Huang

2022

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γ Cep Ab is a typical S-type planet, which occupies a nearly perpendicular planetary orbit relative to the binary. Here, we use a Markov Chain Monte Carlo sampler to conduct a full N-body fitting and derive self-consistent orbital solutions for this hierarchical system. We then employ the eccentric Kozai–Lidov (EKL) mechanism to explain the extremely inclined orbit of the S-type planet γ Cep Ab. The EKL mechanism plays an essential part in our exploration of the significant oscillations of the mutual inclination i mut between the planet and the secondary star. We perform a qualitative analysis and use extensive numerical integrations to investigate the flip conditions and timescales of γ Cep Ab’s orbit. When the planetary mass is 15 M Jup, the planet can reach i mut ∼ 113° given the critical initial conditions of i mut < 60° and e 1 < 0.7. The timescale for the first orbital flip decreases with the increase of the perturbation Hamiltonian. The flipping orbits of γ Cep Ab are confirmed to have a large possibility of remaining stable, based on surfaces of section and the secular stability criterion. Furthermore, we extend the application of EKL to general S-type planetary systems with a 1/a 2 ≤ 0.1, where the most intense excitation of i mut occurs when a 1/a 2 = 0.1 and e 2 ∼ 0.8, and the variation in planetary mass mainly affects the flip possibility where e 1 ≤ 0.3.

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“…However, a complete census of the planets in the solar neighbourhood (d < 15 pc) is still lacking. Such planets will be the prime targets for characterisation with new and upcoming space-and groundbased facilities such as the James Webb Space Telescope (JWST, Gardner et al 2006), the Enhanced Resolution Imager and Spectrograph (ERIS, Davies et al 2018) at the Very Large Telescope (VLT), the Mid-infrared ELT Imager and Spectrograph (METIS, Quanz et al 2015, Brandl et al 2021, and the ArmazoNes high Dispersion Echelle Spectrograph (ANDES, formerly known as High Resolution Echelle Spectrograph, HIRES, Marconi et al 2016) at the Extremely Large Telescope (ELT), and, especially, for future space missions such as the Habitable Exoplanet Observatory (HabEx, Gaudi et al 2020), the Large UV/Optical/IR Surveyor (LUVOIR, Peterson et al 2017, The LUVOIR Team 2019, the Large Interferometer for Exoplanets (LIFE, Quanz et al 2018, Dannert et al 2022, and the Closeby Habitable Exoplanet Survey (CHES, Ji et al 2022), whose goal is to characterise Earth-like planets around the nearest stars. Since large-scale exoplanet searches will not be feasible with such telescopes, or at e-mail: lia.sartori@phys.ethz.ch least not cheaply, it is crucial to use currently available data and instruments to find possible target planets (or a lack thereof) in the solar neighbourhood before next-generation facilities come online.…”

Section: Introductionmentioning

confidence: 99%

L 363-38 b: A planet newly discovered with ESPRESSO orbiting a nearby M dwarf star

Sartori

Delisle

Lendl

et al. 2023

A&A

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Context. Planets around stars in the solar neighbourhood will be prime targets for characterisation with upcoming large space-and ground-based facilities. Since large-scale exoplanet searches will not be feasible with such telescopes, it is crucial to use currently available data and instruments to find possible target planets before next-generation facilities come online. Aims. We aim to detect new extrasolar planets around stars in the solar neighbourhood via blind radial velocity (RV) searching with ESPRESSO. Our target sample consists of nearby stars (d < 11 pc) with few (< 10) or no previous RV measurements. Methods. We used 31 radial velocity measurements obtained with ESPRESSO at the VLT between December 2020 and February 2022 of the nearby M dwarf star (M = 0.21 M , d = 10.23 pc) L 363-38 to derive the orbital parameters of the newly discovered planet. In addition, we used TESS photometry and archival VLT/NaCo high-contrast imaging data to put further constraints on the orbit inclination and the possible planetary system architecture around L 363-38. Results. We present the detection of a new extrasolar planet orbiting the nearby M dwarf star L 363-38. L 363-38 b is a planet with a minimum mass of m p sin(i) = 4.67 ± 0.43 M ⊕ orbiting its star with a period of P = 8.781± 0.007 d, corresponding to a semi-major axis of a = 0.048 ± 0.006 AU, which is smaller than the inner edge of the habitable zone. We further estimate a minimum radius of r p sin(i) ≈ 1.55 − 2.75 R ⊕ and an equilibrium temperature of T eq ≈ 330K.Conclusions. With this study, we further demonstrate the potential of the state-of-the-art spectrograph ESPRESSO in detecting and investigating planetary systems around nearby M dwarf stars, which were inaccessible to previous instruments such HARPS.

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CHES: A Space-borne Astrometric Mission for the Detection of Habitable Planets of the Nearby Solar-type Stars

Cited by 22 publications

References 57 publications

Evolving Morphology of Resolved Stellar Einstein Rings

Evolving Morphology of Resolved Stellar Einstein Rings

Extremely Inclined Orbit of the S-type Planet γ Cep Ab Induced by the Eccentric Kozai–Lidov Mechanism

L 363-38 b: A planet newly discovered with ESPRESSO orbiting a nearby M dwarf star

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