The CARMENES search for exoplanets around M dwarfs

Tal-Or, L.; Zechmeister, M.; Reiners, A.; Jeffers, S. V.; Schöfer, P.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Caballero, J. A.; Aceituno, J.; Bauer, F. F.; Béjar, V. J. S.; Czesla, S.; Dreizler, S.; Fuhrmeister, B.; Hatzes, A. P.; Johnson, E. N.; Kürster, M.; Lafarga, M.; Montes, D.; Morales, J. C.; Reffert, S.; Sadegi, S.; Seifert, W.; Shulyak, D.

doi:10.1051/0004-6361/201732362

Cited by 73 publications

(72 citation statements)

References 71 publications

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“…We imposed the same requirements and only used those CARMENES spectra with a signal-to-noise ratio (S/N) of S /N > 75. Furthermore, as in Passegger et al (2018, hereafter Pass18) we excluded targets with spectral line profiles that cannot be reproduced by a purely photospheric model, i.e., stars with signs of activity that significantly affect the profiles of the lines used by Pass18 for determining stellar parameters; see Tal-Or et al (2018) and Fuhrmeister et al (2018) for the impact of activity on CARMENES target stars. Finally, as in Pass18 we excluded fast rotators.…”

Section: The Samplementioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Schweitzer

Passegger

Cifuentes

et al. 2019

A&A

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175

177

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Aims. We determine the radii and masses of 293 nearby, bright M dwarfs of the CARMENES survey. This is the first time that such a large and homogeneous high-resolution (R > 80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. Methods. We derived the radii using Stefan-Boltzmann's law. We obtained the required effective temperatures T eff from a spectral analysis and we obtained the required luminosities L from integrated broadband photometry together with the Gaia DR2 parallaxes. The mass was then determined using a mass-radius relation that we derived from eclipsing binaries known in the literature. We compared this method with three other methods: (1) We calculated the mass from the radius and the surface gravity log g, which was obtained from the same spectral analysis as T eff . (2) We used a widely used infrared mass-magnitude relation. (3) We used a Bayesian approach to infer stellar parameters from the comparison of the absolute magnitudes and colors of our targets with evolutionary models. Results. Between spectral types M0 V and M7 V our radii cover the range 0.1 R < R < 0.6 R with an error of 2-3% and our masses cover 0.09 M < M < 0.6 M with an error of 3-5%. We find good agreement between the masses determined with these different methods for most of our targets. Only the masses of very young objects show discrepancies. This can be well explained with the assumptions that we used for our methods.Article published by EDP Sciences A68, page 1 of 16 A&A 625, A68 (2019)

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Section: The Samplementioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Schweitzer

Passegger

Cifuentes

et al. 2019

A&A

Self Cite

175

177

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“…In this work we concentrate on the subsample of 31 stars presented in Tal-Or et al (2018) which we called the RV-loud sample. All these stars had at least 11 measurements over the last two years (2016)(2017), projected rotational velocity of υ sin i > 2 km s −1 , and radial velocity scatter amplitude > 10 m s −1 (as measured from the visual arm of the instrument).…”

Section: Observationsmentioning

confidence: 99%

“…All these stars had at least 11 measurements over the last two years (2016)(2017), projected rotational velocity of υ sin i > 2 km s −1 , and radial velocity scatter amplitude > 10 m s −1 (as measured from the visual arm of the instrument). Further details about RV-loud sample are summarized in Table 1 in Tal-Or et al (2018). In this work we make use of the near-infrared arm (NIR) of CARMENES because this is where our magnetically sensitive spectral features are located.…”

Section: Observationsmentioning

confidence: 99%

Magnetic fields in M dwarfs from the CARMENES survey

Shulyak

Reiners

Nagel

et al. 2019

A&A

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Context. M dwarfs are known to generate the strongest magnetic fields among main-sequence stars with convective envelopes, but the link between the magnetic fields and underlying dynamo mechanisms, rotation, and activity still lacks a consistent picture. Aims. In this work we measure magnetic fields from the high-resolution near-infrared spectra taken with the CARMENES radialvelocity planet survey in a sample of 29 active M dwarfs and compare our results against stellar parameters. Methods. We use the state-of-the-art radiative transfer code to measure total magnetic flux densities from the Zeeman broadening of spectral lines and filling factors. Results. We detect strong kG magnetic fields in all our targets. In 16 stars the magnetic fields were measured for the first time. Our measurements are consistent with the magnetic field saturation in stars with rotation periods P < 4 d. The analysis of the magnetic filling factors reveal two different patterns of either very smooth distribution or a more patchy one, which can be connected to the dynamo state of the stars and/or stellar mass. Conclusions. Our measurements extend the list of M dwarfs with strong surface magnetic fields. They also allow us to better constrain the interplay between the magnetic energy, stellar rotation, and underlying dynamo action. The high spectral resolution and observations at near-infrared wavelengths are the beneficial capabilities of the CARMENES instrument that allow us to address important questions about the stellar magnetism.

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“…However, the detection of low-mass/small-sized planets is not an easy task not only because of the very small photoelectric and RV signals, but also because of the activity signals coming from the host stars that often have the same magnitude as the planetary signal and can strongly perturb the detection of these planets and/or mimic a planetary signal [e.g. [248][249][250][251][252][253][254]. These difficulties not only limits the number of detected low-mass planets, but also make very hard to construct a control sample of stars without low-mass planets for RV surveys and make practically impossible 30 for transit surveys [255].…”

Section: Low-mass Planets and Metallicitymentioning

confidence: 99%

Heavy Metal Rules. I. Exoplanet Incidence and Metallicity

Adibekyan

2019

Geosciences

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Discovery of only handful of exoplanets required to establish a correlation between giant planet occurrence and metallicity of their host stars. More than 20 years have already passed from that discovery, however, many questions are still under lively debate: What is the origin of that relation? what is the exact functional form of the giant planet -metallicity relation (in the metal-poor regime)?, does such a relation exist for terrestrial planets? All these question are very important for our understanding of the formation and evolution of (exo)planets of different types around different types of stars and are subject of the present manuscript. Besides making a comprehensive literature review about the role of metallicity on the formation of exoplanets, I also revisited most of the planet -metallicity related correlations reported in the literature using a large and homogeneous data provided by the SWEET-Cat catalog. This study lead to several new results and conclusions, two of which I believe deserve to be highlighted in the abstract: i) The hosts of sub-Jupiter mass planets (∼0.6 -0.9 M ) are systematically less metallic than the hosts of Jupiter-mass planets. This result might be related to the longer disk lifetime and higher amount of planet building materials available at high metallicities, which allow a formation of more massive Jupiter-like planets. ii) Contrary to the previous claims, our data and results do not support the existence of a breakpoint planetary mass at 4 M above and below which planet formation channels are different. However, the results also suggest that planets of the same (high) mass can be formed through different channels depending on the (disk) stellar mass i.e. environmental conditions.

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The CARMENES search for exoplanets around M dwarfs

Cited by 73 publications

References 71 publications

The CARMENES search for exoplanets around M dwarfs

The CARMENES search for exoplanets around M dwarfs

Magnetic fields in M dwarfs from the CARMENES survey

Heavy Metal Rules. I. Exoplanet Incidence and Metallicity

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