The CARMENES search for exoplanets around M dwarfs

Trifonov, T.; Lee, M. H.; Kürster, M.; Henning, Th.; Grishin, Evgeni; Stock, S.; Tjoa, J.; Caballero, J. A.; Wong, K. H.; Bauer, F. F.; Quirrenbach, A.; Zechmeister, M.; Ribas, I.; Reffert, S.; Reiners, A.; Amado, P. J.; Kossakowski, D.; Azzaro, M.; Béjar, V. J. S.; Cortés-Contreras, M.; Hatzes, A. P.; Jeffers, S. V.; Kaminski, A.; Lafarga, M.; Montes, D.; Morales, J. C.; Pavlov, A.; Rodríguez‐López, C.; Schmitt, J. H. M. M.; Solano, E.; Barnes, Rory

doi:10.1051/0004-6361/201936987

Cited by 22 publications

(16 citation statements)

References 107 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The spectra were processed following the standard CARMENES data flow (Caballero et al 2016) that has been extensively used by previous works (e.g. Zechmeister et al 2018;Morales et al 2019;Trifonov et al 2020). In our analyses, we only used radial-velocities from the visual (VIS) channel which had mean errors of 2.6 m/s.…”

Section: Carmenesmentioning

confidence: 99%

A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS

Espinoza,

Pallé,

Kemmer

et al. 2022

Preprint

View full text Add to dashboard Cite

We report the discovery and characterization of TOI-1759 b, a temperate (400 K) sub-Neptune-sized exoplanet orbiting the M dwarf TOI-1759 (TIC 408636441). TOI-1759 b was observed by TESS to transit on sectors 16, 17 and 24, with only one transit observed per sector, creating an ambiguity on the orbital period of the planet candidate. Ground-based photometric observations, combined with radial-velocity measurements obtained with the CARMENES spectrograph, confirm an actual period of 18.85019±0.00014 d. A joint analysis of all available photometry and radial velocities reveal a radius of 3.17 ± 0.10 R ⊕ and a mass of 10.8 ± 1.5 M ⊕ . Combining this with the stellar properties derived for TOI-1759 (R = 0.597 ± 0.015 R ; M = 0.606 ± 0.020 M ; T eff = 4065 ± 51 K), we compute a transmission spectroscopic metric (TSM) value of over 80 for the planet, making it a good target for transmission spectroscopy studies. TOI-1759 b is among the top five temperate, small exoplanets (T eq < 500 K, R p < 4 R ⊕ ) with the highest TSM discovered to date. Two additional signals with periods of 80 d and > 200 d seem to be present in our radial velocities. While our data suggest both could arise from stellar activity, the later signal's source and periodicity are hard to pinpoint given the ∼ 200 d baseline of our radial-velocity campaign with CARMENES. Longer baseline radial-velocity campaigns should be performed in order to unveil the true nature of this long period signal.

show abstract

Section: Carmenesmentioning

confidence: 99%

A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS

Espinoza,

Pallé,

Kemmer

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Being designed for high-precision RV measurements of cool stars, it comprises two spectrograph channels with wavelength ranges of 0.52 to 0.96 µm and 0.96 to 1.71 µm, respectively, with spectral resolutions of R ≈ 80 000-96 000 (Quirrenbach et al 2014) capable of providing an RV accuracy of ∼ 1.2 m s −1 (Bauer et al 2020). More than 350 stars from the CARMENES guaranteed time observations (GTO) sample have been monitored since January 2016, resulting in 26 planet detections to date (e.g., Bluhm et al 2020;Nowak et al 2020, see Sabotta et al 2021 for an exhaustive review), as well as several planet confirmations (Trifonov et al 2018(Trifonov et al , 2020Sarkis et al 2018;Lalitha et al 2019;Stock et al 2020a).…”

Section: Introductionmentioning

confidence: 99%

CARMENES input catalog of M dwarfs

Perdelwitz

Mittag

Tal-Or

et al. 2021

A&A

Self Cite

View full text Add to dashboard Cite

Context. Radial-velocity (RV) jitter caused by stellar magnetic activity is an important factor in state-of-the-art exoplanet discovery surveys such as CARMENES. Stellar rotation, along with heterogeneities in the photosphere and chromosphere caused by activity, can result in false-positive planet detections. Hence, it is necessary to determine the stellar rotation period and compare it to any putative planetary RV signature. Long-term measurements of activity indicators such as the chromospheric emission in the Ca ii H&K lines (R HK ) enable the identification of magnetic activity cycles. Aims. In order to determine stellar rotation periods and study the long-term behavior of magnetic activity of the CARMENES guaranteed time observations (GTO) sample, it is advantageous to extract R HK time series from archival data, since the CARMENES spectrograph does not cover the blue range of the stellar spectrum containing the Ca ii H&K lines. Methods. We have assembled a catalog of 11 634 archival spectra of 186 M dwarfs acquired by seven different instruments covering the Ca ii H&K regime: ESPaDOnS, FEROS, HARPS, HIRES, NARVAL, TIGRE, and UVES. The relative chromospheric flux in these lines, R HK , was directly extracted from the spectra by rectification with PHOENIX synthetic spectra via narrow passbands around the Ca ii H&K line cores. Results. The combination of archival spectra from various instruments results in time series for 186 stars from the CARMENES GTO sample. As an example of the use of the catalog, we report the tentative discovery of three previously unknown activity cycles of M dwarfs. Conclusions. We conclude that the method of extracting R HK with the use of model spectra yields consistent results for different instruments and that the compilation of this catalog will enable the analysis of long-term activity time series for a large number of M dwarfs.

show abstract

“…In addition to detecting and characterising the orbits of exoplanets (e.g. Trifonov et al 2018Trifonov et al , 2020Luque et al 2019;Zechmeister et al 2019) and their atmospheres (Nortmann et al 2018;Alonso-Floriano et al 2019;Yan et al 2019), the survey represents a unique opportunity to gain insights into the nature of M dwarfs (namely, their photospheric parameters, chemical compositions, magnetic fields, and chromospheric activity levels) in a statistically relevant way (Fuhrmeister et al 2018(Fuhrmeister et al , 2020Passegger et al 2018Passegger et al , 2019Hintz et al 2019Hintz et al , 2020Schöfer et al 2019;Schweitzer et al 2019;Abia et al 2020;Shan et al 2021).…”

Section: Introductionmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn

Marfil,

Tabernero,

Montes

et al. 2021

Preprint

View full text Add to dashboard Cite

We determined effective temperatures, surface gravities, and metallicities for a sample of 343 M dwarfs observed with CARMENES, the double-channel, high-resolution spectrograph installed at the 3.5 m telescope at Calar Alto Observatory. We employed SteParSyn, a Bayesian spectral synthesis implementation particularly designed to infer the stellar atmospheric parameters of late-type stars following a Markov chain Monte Carlo approach. We made use of the BT-Settl model atmospheres and the radiative transfer code turbospectrum to compute a grid of synthetic spectra around 75 magnetically insensitive Fe i and Ti i lines plus the TiO γ and bands. To avoid any potential degeneracy in the parameter space, we imposed Bayesian priors on T eff and log g based on the comprehensive, multi-band photometric data available for the sample. We find that this methodology is suitable down to M7.0 V, where refractory metals such as Ti are expected to condense in the stellar photospheres. The derived T eff , log g, and [Fe/H] range from 3000 to 4200 K, 4.5 to 5.3 dex, and −0.7 to 0.2 dex, respectively. Although our T eff scale is in good agreement with the literature, we report large discrepancies in the [Fe/H] scales, which might arise from the different methodologies and sets of lines considered. However, our [Fe/H] is in agreement with the metallicity distribution of FGK-type stars in the solar neighbourhood and correlates well with the kinematic membership of the targets in the Galactic populations. Lastly, excellent agreement in T eff is found for M dwarfs with interferometric angular diameter measurements, as well as in the [Fe/H] between the components in the wide physical FGK+M and M+M systems included in our sample.

show abstract

The CARMENES search for exoplanets around M dwarfs

Cited by 22 publications

References 107 publications

A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS

A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS

CARMENES input catalog of M dwarfs

The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn

Contact Info

Product

Resources

About