Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization

Luque, R.; Πάλλη, Ε.; Kossakowski, D.; Dreizler, S.; Kemmer, J.; Espinoza, N.; Burt, Jennifer; Anglada-Escudé, G.; Béjar, V. J. S.; Caballero, J. A.; Collins, Karen A.; Collins, Kevin I.; Cortés-Contreras, M.; Díez-Alonso, E.; Feng, Fabo; Hatzes, A. P.; Hellier, C.; Henning, Th.; Jeffers, S. V.; Kaltenegger, Lisa; Kürster, M.; Madden, Jack; Molaverdikhani, Karan; Montes, D.; Narita, Norio; Nowak, G.; Ofir, A.; Oshagh, M.; Parviainen, H.; Quirrenbach, A.; Reffert, S.; Reiners, A.; Rodríguez‐López, C.; Schlecker, Martin; Stock, S.; Trifonov, T.; Winn, Joshua N.; Osorio, M. R. Zapatero; Zechmeister, M.; Amado, P. J.; Anderson, D. R.; Batalha, Natalie M.; Bauer, F. F.; Bluhm, P.; Burke, Christopher J.; Butler, R. Paul; Caldwell, Douglas A.; Chen, G.; Crane, Jeffrey D.; Dragomir, Diana; Dressing, Courtney D.; Dynes, Scott; Jenkins, Jon M.; Kaminski, A.; Klahr, Hubert; Kotani, Takayuki; Lafarga, M.; Latham, David W.; Lewin, Pablo; McDermott, Scott; Montañés-Rodŕıguez, P.; Morales, J. C.; Murgas, F.; Nagel, E.; Pedraz, S.; Ribas, I.; Ricker, G.; Rowden, Pamela; Seager, Sara; Shectman, Stephen; Tamura, Motohide; Teske, Johanna; Twicken, Joseph D.; Vanderspeck, R.; Wang, S. X.; Wohler, Bill

doi:10.1051/0004-6361/201935801

Cited by 117 publications

(54 citation statements)

References 138 publications

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“…With its unprecedented precision, HARPS is the southern hemisphere backbone Doppler validation instrument for the Transiting Exoplanet Survey Satellite (TESS; Ricker et al 2015), which is uncovering hundreds of small rocky transiting exoplanet candidates around nearby stars. HARPS also offers a large publicly available spectral archive, which has already allowed the post-detection Doppler validation of TESS candidates, for example GJ 143, HD 23472 (Trifonov et al 2019a), HD 15337 (Gandolfi et al 2019;Dumusque et al 2019) and GJ 357 (Luque et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Public HARPS radial velocity database corrected for systematic errors

Trifonov

Tal-Or

Zechmeister

et al. 2020

A&A

157

193

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Context. The High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph is mounted since 2003 at the ESO 3.6 m telescope in La Silla and provides state-of-the-art stellar radial velocity (RV) measurements with a precision down to ∼ 1 m s −1 . The spectra are extracted with a dedicated data-reduction software (DRS) and the RVs are computed by cross correlating with a numerical mask. Aims. The aim of this study is three-fold: (i) Create an easy access to the public HARPS RV data set. (ii) Apply the new public SpEctrum Radial Velocity AnaLyser (SERVAL) pipeline to the spectra, and produce a more precise RV data set. (iii) Check whether the precision of the RVs can be further improved by correcting for small nightly systematic effects. Methods. For each star observed with HARPS, we downloaded the publicly available spectra from the ESO archive, and recomputed the RVs with SERVAL. This was based on fitting each observed spectrum with a high signal-to-noise ratio template created by co-adding all the available spectra of that star. We then computed nightly zero points (NZPs) by averaging the RVs of quiet stars. Results. Analysing the RVs of the most RV-quiet stars, whose RV scatter is < 5 m s −1 , we find that SERVAL RVs are on average more precise than DRS RVs by a few percent. Investigating the NZP time series, we find three significant systematic effects, whose magnitude is independent of the software used for the RV derivation: (i) stochastic variations with a magnitude of ∼ 1 m s −1 ; (ii) longterm variations, with a magnitude of ∼ 1 m s −1 and a typical timescale of a few weeks; and (iii) 20-30 NZPs significantly deviating by few m s −1 . In addition, we find small ( 1 m s −1 ) but significant intra-night drifts in DRS RVs before the 2015 intervention, and in SERVAL RVs after it. We confirm that the fibre exchange in 2015 caused a discontinuous RV jump, which strongly depends on the spectral type of the observed star: from ∼ 14 m s −1 for late F-type stars, to ∼ −3 m s −1 for M dwarfs. The combined effect of extracting the RVs with SERVAL and correcting them for the systematics we find is an improved average RV precision: ∼ 5% improvement for spectra taken before the 2015 intervention, and ∼ 15% improvement for spectra taken after it. To demonstrate the quality of the new RV data set, we present an updated orbital solution of the GJ 253 two-planet system. Conclusions. Our NZP-corrected SERVAL RVs can be retrieved from a user-friendly, public database. It provides more than 212 000 RVs for about 3000 stars along with many auxiliary information, such as the NZP corrections, various activity indices, and DRS-CCF products.Differential RV from SERVAL corrected for BERV, SA, drift, (non-NZP corrected). (d) RV from DRS corrected for BERV, SA, drift, (non-NZP corrected). (e) Differential RV from SERVAL corrected for BERV, SA, drift, (non-NZP corrected, joint RV calculation with -pre and -post fibre upgrade data.) (f) Chromatic index from SERVAL. (g) Differential line width from SERVAL. (h) Hα index from SERV...

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Section: Introductionmentioning

confidence: 99%

Public HARPS radial velocity database corrected for systematic errors

Trifonov

Tal-Or

Zechmeister

et al. 2020

A&A

157

193

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“…Their significantly lower mass and luminosity when compared to Sun-like stars make them suitable for the detection of lower mass planets orbiting in the so-called habitable zone (HZ), where the surface temperature would be favorable for liquid water to exist. Planets in the HZ have already been discovered around low-mass M dwarf neighbors such as Proxima Centauri (Anglada-Escudé et al 2016), LHS 1140 (Dittmann et al 2017), HD 147379 (Reiners et al 2018a), GJ 752A (Kaminski et al 2018), and GJ 357 (Luque et al 2019), among others. Of special interest for Doppler surveys are also potentially habitable M-dwarf multiple planet systems consisting of Earth-size planets such as GJ 1069 , or the ultra-cool M dwarfs TRAPPIST-1 (Gillon et al 2017) and Teegarden's star ).…”

Section: Introductionmentioning

confidence: 99%

“…Of special interest for Doppler surveys are also potentially habitable M-dwarf multiple planet systems consisting of Earth-size planets such as GJ 1069 , or the ultra-cool M dwarfs TRAPPIST-1 (Gillon et al 2017) and Teegarden's star ). As of October 2019, more than 100 M-dwarf planetary systems have been discovered via the radial velocity (RV) method (Martínez-Rodríguez et al 2019) 1 , Many more are expected to be detected with the transit technique thanks to the Transiting Exoplanet Survey Satellite (TESS; Ricker et al 2015), which already delivered the first planet detections around Mdwarf stars such as L 95-98 (Kostov et al 2019;Cloutier et al 2019), TOI 270 (LEHPM 3808; Günther et al 2019), and GJ 357 (Luque et al 2019), which are in fact all multi-planet systems.…”

Section: Introductionmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Trifonov

Lee²,

Kürster

et al. 2020

A&A

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Context. GJ 1148 is an M-dwarf star hosting a planetary system composed of two Saturn-mass planets in eccentric orbits with periods of 41.38 and 532.02 days. Aims. We reanalyze the orbital configuration and dynamics of the GJ 1148 multi-planetary system based on new precise radial velocity (RV) measurements taken with CARMENES. Methods. We combined new and archival precise Doppler measurements from CARMENES with those available from HIRES for GJ 1148 and modeled these data with a self-consistent dynamical model. We studied the orbital dynamics of the system using the secular theory and direct N-body integrations. The prospects of potentially habitable moons around GJ 1148 b were examined. Results. The refined dynamical analyses show that the GJ 1148 system is long-term stable in a large phase-space of orbital parameters with an orbital configuration suggesting apsidal alignment, but not in any particular high-order mean-motion resonant commensurability. GJ 1148 b orbits inside the optimistic habitable zone (HZ). We find only a narrow stability region around the planet where exomoons can exist. However, in this stable region exomoons exhibit quick orbital decay due to tidal interaction with the planet. Conclusions. The GJ 1148 planetary system is a very rare M-dwarf planetary system consisting of a pair of gas giants, the inner of which resides in the HZ. We conclude that habitable exomoons around GJ 1148 b are very unlikely to exist.

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“…The main goal of CARMENES is to discover and characterize Earth-like planets around an initial sample of about 300 M dwarfs (Reiners et al 2018b). To date, the program has already confirmed eight planet candidates from large-scale photometric and spectroscopic surveys (e.g., Trifonov et al 2018;Sarkis et al 2018) and detected more than ten new planets (e.g., Reiners et al 2018a;Kaminski et al 2018;Luque et al 2018Luque et al , 2019Ribas et al 2018;Nagel et al 2019;Perger et al 2019;Zechmeister et al 2019;Morales et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

González-Álvarez

Osorio

Caballero

et al. 2020

A&A

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Aims. We report on radial velocity time series for two M0.0 V stars, GJ 338 B and GJ 338 A, using the CARMENES spectrograph, complemented by ground-telescope photometry from Las Cumbres and Sierra Nevada observatories. We aim to explore the presence of small planets in tight orbits using the spectroscopic radial velocity technique. Methods. We obtained 159 and 70 radial velocity measurements of GJ 338 B and A, respectively, with the CARMENES visible channel between 2016 January and 2018 October. We also compiled additional relative radial velocity measurements from the literature and a collection of astrometric data that cover 200 a of observations to solve for the binary orbit. Results. We found dynamical masses of 0.64 ± 0.07 M for GJ 338 B and 0.69 ± 0.07 M for GJ 338 A. The CARMENES radial velocity periodograms show significant peaks at 16.61 ± 0.04 d (GJ 338 B) and 16.3 +3.5 −1.3 d (GJ 338 A), which have counterparts at the same frequencies in CARMENES activity indicators and photometric light curves. We attribute these to stellar rotation. GJ 338 B shows two additional, significant signals at 8.27 ± 0.01 and 24.45 ± 0.02 d, with no obvious counterparts in the stellar activity indices. The former is likely the first harmonic of the star's rotation, while we ascribe the latter to the existence of a super-Earth planet with a minimum mass of 10.27 +1.47 −1.38 M ⊕ orbiting GJ 338 B. We have not detected signals of likely planetary origin around GJ 338 A. Conclusions. GJ 338 Bb lies inside the inner boundary of the habitable zone around its parent star. It is one of the least massive planets ever found around any member of stellar binaries. The masses, spectral types, brightnesses, and even the rotational periods are very similar for both stars, which are likely coeval and formed from the same molecular cloud, yet they differ in the architecture of their planetary systems.

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Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization

Cited by 117 publications

References 138 publications

Public HARPS radial velocity database corrected for systematic errors

Public HARPS radial velocity database corrected for systematic errors

The CARMENES search for exoplanets around M dwarfs

The CARMENES search for exoplanets around M dwarfs

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