The CARMENES search for exoplanets around M dwarfs

Passegger, V. M.; Reiners, A.; Jeffers, S. V.; Berg, S.; Schöfer, P.; Caballero, J. A.; Schweitzer, A.; Amado, P. J.; Béjar, V. J. S.; Cortés-Contreras, M.; Hatzes, A. P.; Kürster, M.; Montes, D.; Pedraz, S.; Quirrenbach, A.; Ribas, I.; Seifert, W.

doi:10.1051/0004-6361/201732312

Cited by 115 publications

(127 citation statements)

References 44 publications

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“…For the model calculations, including the effect of metallicity would be relatively straightforward. Comparison to observed spectra, however, is hampered by uncertainties of the observed stars' metallicity, particularly in low-mass stars where the model spectra are known to be imprecise (see Artigau et al 2018;Passegger et al 2018). Relative to the other effects considered, metallicity is expected to create only minor deviations for the stars considered in this paper.…”

Section: Determining Radial Velocity Photon Noisementioning

confidence: 99%

Radial Velocity Photon Limits for the Dwarf Stars of Spectral Classes F–M

Reiners¹,

Zechmeister²

2020

ApJS

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The determination of extrasolar planet masses with the radial velocity (RV) technique requires spectroscopic Doppler information from the planet's host star, which varies with stellar brightness and temperature. We analyze Doppler information in spectra of F-M dwarfs utilizing empirical information from HARPS and CARMENES, and from model spectra. We come to the conclusions that an optical setup (BV R-bands) is more efficient that a near-infrared one (Y JHK) in dwarf stars hotter than 3200 K.We publish a catalogue of 46,480 well-studied F-M dwarfs in the solar neighborhood and compare their distribution to more than one million stars from Gaia DR2. For all stars, we estimate the RV photon noise achievable in typical observations assuming no activity jitter and slow rotation. We find that with an ESPRESSO-like instrument at an 8m-telescope, a photon noise limit of 10 cm s −1 or lower can be reached in more than 280 stars in a 5 min observation. At 4m-telescopes, a photon noise limit of 1 m s −1 can be reached in a 10 min exposure in approx. 10,000 predominantly sun-like stars with a HARPS-like (optical) instrument. The same applies to ∼3000 stars for a red-optical setup covering the RIz-bands, and to ∼700 stars for a near-infrared instrument. For the latter two, many of the targets are nearby M dwarfs. Finally, we identify targets in which Earth-mass planets within the liquid water habitable zone can cause RV amplitudes comparable to the RV photon noise. Assuming the same exposure times, we find that an ESPRESSO-like instrument can reach this limit for 1 M ⊕ planets in more than 1000 stars. The optical, red-optical, and near-infrared configurations reach the limit for 2 M ⊕ planets in approximately 500, 700, and 200 stars, respectively.

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Section: Determining Radial Velocity Photon Noisementioning

confidence: 99%

Radial Velocity Photon Limits for the Dwarf Stars of Spectral Classes F–M

Reiners¹,

Zechmeister²

2020

ApJS

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“…The basic photospheric parameters T eff , log g, and [Fe/H] were measured as in Passegger et al (2018), who fit the latest version of the PHOENIX-ACES models (Husser et al 2013) to CARMENES spectra. We computed the luminosity from the Gaia DR2 parallax and multiwavelength photometry from B to W4 as described in Kaminski et al (2018) and Luque et al (2018).…”

Section: Host Star Propertiesmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Nagel

Czesla

Schmitt

et al. 2019

A&A

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We report the detection of a Neptune-mass exoplanet around the M4.0 dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations obtained with the CARMENES spectrograph. The RV variations of GJ 4276 are best explained by the presence of a planetary companion that has a minimum mass of m b sin i ≈ 16 M ⊕ on a P b = 13.35 day orbit. The analysis of the activity indicators and spectral diagnostics exclude stellar induced RV perturbations and prove the planetary interpretation of the RV signal. We show that a circular single-planet solution can be excluded by means of a likelihood ratio test. Instead, we find that the RV variations can be explained either by an eccentric orbit or interpreted as a pair of planets on circular orbits near a period ratio of 2:1. Although the eccentric single-planet solution is slightly preferred, our statistical analysis indicates that none of these two scenarios can be rejected with high confidence using the RV time series obtained so far. Based on the eccentric interpretation, we find that GJ 4276 b is the most eccentric (e b = 0.37) exoplanet around an M dwarf with such a short orbital period known today.

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“…A summary of the basic stellar properties of both targets is presented in Table 1. The photospheric parameters such as the effective temperature T eff , surface gravity log g, and metallicity [Fe/H] of the targets were determined in the CARMENES framework by Passegger et al (2018) using the PHOENIX-ACES model grid (Husser et al 2013). The stellar masses and radii were determined based on the photospheric parameters and a mass-radius relation.…”

Section: Targetsmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Lalitha

Baroch

Morales

et al. 2019

A&A

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Although M dwarfs are known for high levels of stellar activity, they are ideal targets for the search of low-mass exoplanets with the radial velocity (RV) method. We report the discovery of a planetary-mass companion around LSPM J2116+0234 (M3.0 V) and confirm the existence of a planet orbiting GJ 686 (BD+18 3421; M1.0 V). The discovery of the planet around LSPM J2116+0234 is based on CARMENES RV observations in the visual and near-infrared channels. We confirm the planet orbiting around GJ 686 by analyzing the RV data spanning over two decades of observationsfrom CARMENES VIS, HARPS-N, HARPS, and HIRES. We find planetary signals at 14.44 and 15.53 d in the RV data for LSPM J2116+0234 and GJ 686, respectively. Additionally, the RV, photometric time series, and various spectroscopic indicators show hints of variations of 42 d for LSPM J2116+0234 and 37 d for GJ 686, which we attribute to the stellar rotation periods. The orbital parameters of the planets are modeled with Keplerian fits together with correlated noise from the stellar activity. A mini-Neptune with a minimum mass of 11.8 M⊕ orbits LSPM J2116+0234 producing a RV semi-amplitude of 6.19 m s−1, while a super-Earth of mass 6.6 M⊕ orbits GJ 686 and produces a RV semi-amplitude of 3.0 m s−1. Both LSPM J2116+0234 and GJ 686 have planetary companions populating the regime of exoplanets with masses lower than 15 M⊕ and orbital periods <20 d.

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The CARMENES search for exoplanets around M dwarfs

Cited by 115 publications

References 44 publications

Radial Velocity Photon Limits for the Dwarf Stars of Spectral Classes F–M

Radial Velocity Photon Limits for the Dwarf Stars of Spectral Classes F–M

The CARMENES search for exoplanets around M dwarfs

The CARMENES search for exoplanets around M dwarfs

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