The CARMENES search for exoplanets around M dwarfs

Lafarga, M.; Ribas, I.; Lovis, C.; Perger, M.; Zechmeister, M.; Bauer, F. F.; Kürster, M.; Cortés-Contreras, M.; Morales, J. C.; Herrero, E.; Rosich, A.; Baroch, D.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Alacid, J. M.; Béjar, V. J. S.; Dreizler, S.; Hatzes, A. P.; Henning, Thomas; Jeffers, S. V.; Kaminski, A.; Montes, D.; Pedraz, S.; Rodríguez‐López, C.; Schmitt, J. H. M. M.

doi:10.1051/0004-6361/201937222

Cited by 76 publications

(81 citation statements)

References 59 publications

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“…Indeed, due to blended lines that are in some way unique for each star depending on the stellar temperature, metallicity, v sin(i) or instrumental resolution, a generic mask will in some case produce spurious RV signals, which was demonstrated in Cretignier et al (2020a). We note that similarly to Dumusque (2018) and Cretignier et al (2020a), Lafarga et al (2020) showed that tailored lines selections, produced by their public code RACCOON, can be useful to boost the S/N and decrease the photon noise, which produces in general better RV precision.…”

Section: Stellar Mask Optimisation and Lbl Rvsmentioning

confidence: 63%

YARARA: Significant improvement in RV precision through post-processing of spectral time series

Cretignier

Dumusque

Hara

et al. 2021

A&A

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Aims. Even the most precise radial-velocity instruments gather high-resolution spectra that present systematic errors that a data reduction pipeline cannot identify and correct for efficiently by simply analysing a set of calibrations and a single science frame. In this paper we aim at improving the radial-velocity precision of HARPS measurements by 'cleaning' individual extracted spectra using the wealth of information contained in spectral time series. Methods. We developed YARARA, a post-processing pipeline designed to clean high-resolution spectra of instrumental systematics and atmospheric contamination. Spectra are corrected for: tellurics, interference patterns, detector stitching, ghosts, and fibre B contaminations, as well as more advanced spectral line-by-line corrections. YARARA uses principal component analysis on spectral time series with prior information to disentangle contaminations from real Doppler shifts. We applied YARARA to three systems, HD10700, HD215152, and HD10180, and compared our results to the standard HARPS data reduction software and the SERVAL post-processing pipeline.Results. We ran YARARA on the radial-velocity dataset of three stars intensively observed with HARPS: HD10700, HD215152, and HD10180. For HD10700, we show that YARARA enables us to obtain radial-velocity measurements that present an rms smaller than 1 m s −1 over the 13 years of the HARPS observations, which is 20% and 10% better than the HARPS data reduction software and the SERVAL post-processing pipeline, respectively. We also injected simulated planets into the data of HD10700 and demonstrated that YARARA does not alter pure Doppler-shifted signals. For HD215152, we demonstrated that the 1-year signal visible in the periodogram becomes marginal after processing with YARARA and that the signals of the known planets become more significant. Finally, for HD10180, the six known exoplanets are well recovered, although different orbital parameters and planetary masses are provided by the new reduced spectra. Conclusions. The post-processing correction of spectra using spectral time series allows the radial-velocity precision of HARPS data to be significantly improved and demonstrates that for the extremely quiet star HD10700 a radial-velocity rms better than 1 m/s can be reached over the 13 years of HARPS observations. Since the processing proposed in this paper does not absorb planetary signals, its application to intensively followed systems is promising and will certainly result in advances in the detections of the lightest exoplanets.

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Section: Stellar Mask Optimisation and Lbl Rvsmentioning

confidence: 63%

YARARA: Significant improvement in RV precision through post-processing of spectral time series

Cretignier

Dumusque

Hara

et al. 2021

A&A

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“…The SIMBAD query provides line-of-sight velocities for 287 objects. Among them, 129 come from Gaia DR2 or its catalogue of radial velocity standard stars (Soubiran et al 2018), and 48 precise measurements come from Lafarga et al (2020). Radial velocities of multiple systems may be inaccurate, but we tried to use the same source for the two components of a binary system Notes.…”

Section: Line-of-sight Velocitiesmentioning

confidence: 99%

The 10 parsec sample in the Gaia era

Reylé

Jardine²,

Fouqué

et al. 2021

A&A

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Context. The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be seen and understood with precise data. This work is triggered by the most recent data release of the astrometric space mission Gaia and uses its unprecedented high precision parallax measurements to review the census of objects within 10 pc. Aims. The first aim of this work was to compile all stars and brown dwarfs within 10 pc observable by Gaia and compare it with the Gaia Catalogue of Nearby Stars as a quality assurance test. We complement the list to get a full 10 pc census, including bright stars, brown dwarfs, and exoplanets. Methods. We started our compilation from a query on all objects with a parallax larger than 100 mas using the Set of Identifications, Measurements, and Bibliography for Astronomical Data database (SIMBAD). We completed the census by adding companions, brown dwarfs with recent parallax measurements not in SIMBAD yet, and vetted exoplanets. The compilation combines astrometry and photometry from the recent Gaia Early Data Release 3 with literature magnitudes, spectral types, and line-of-sight velocities. Results. We give a description of the astrophysical content of the 10 pc sample. We find a multiplicity frequency of around 28%. Among the stars and brown dwarfs, we estimate that around 61% are M stars and more than half of the M stars are within the range from M3.0 V to M5.0 V. We give an overview of the brown dwarfs and exoplanets that should be detected in the next Gaia data releases along with future developments. Conclusions. We provide a catalogue of 541 stars, brown dwarfs, and exoplanets in 339 systems, within 10 pc from the Sun. This list is as volume-complete as possible from current knowledge and it provides benchmark stars that can be used, for instance, to define calibration samples and to test the quality of the forthcoming Gaia releases. It also has a strong outreach potential.

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“…All redetermined parameters (T eff , L , R , and M ) match the values published by Gaidos et al (2014) and Gaia Collaboration (2018) within 1σ. Furthermore, we used the precise astrometric data of Gaia DR2, the absolute RV measured on the stacked CARMENES spectra as in Lafarga et al (2020), and the prescription of Johnson & Soderblom (1987) for measuring the Galactocentric space velocities UVW. Using this kinematic information with the BANYAN Σ tool (Gagné et al 2018), we classified TOI-1235 as a field star in the Galactic thin disk not associated with any young stellar kinematic group.…”

Section: Stellar Propertiesmentioning

confidence: 99%

Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?

Bluhm

Luque

Espinoza

et al. 2020

A&A

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We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384–1735–1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than that of Earth. In particular, we measure a mass of Mp = 5.9 ± 0.6 M⊕ and a radius of Rp = 1.69 ± 0.08 R⊕, which together result in a density of ρp = 6.7− 1.1+ 1.3 g cm−3. When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass places our discovery in the radius gap, which is a transition region between rocky planets and planets with significant atmospheric envelopes. A few examples of planets occupying the radius gap are known to date. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R⊕ or larger at the insolation levels received by TOI-1235 b (~60 S⊕). This makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.

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The CARMENES search for exoplanets around M dwarfs

Cited by 76 publications

References 59 publications

YARARA: Significant improvement in RV precision through post-processing of spectral time series

YARARA: Significant improvement in RV precision through post-processing of spectral time series

The 10 parsec sample in the Gaia era

Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?

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