Searching for exoplanets around M-dwarfs with ExTrA

2021 ◽  
Author(s):  
Marion Cointepas ◽  
Xavier Bonfils ◽  
Jose Almenara
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Disruptive Effect ◽  
M Dwarfs ◽  
Optical Photometry ◽  
New Approach ◽  
New Instrument ◽  
Spectroscopic Information ◽  
M Dwarf ◽  
As Effects

<p>ExTrA (Exoplanets in Transits and their Atmospheres - Bonfils et al. 2015) is a new instrument composed of an array of three 60-cm telescopes capable of infrared photometry and located in La Silla, Chile. This instrument relies on a new approach that involves combining optical photometry with spectroscopic information in order to mitigate the disruptive effect of Earth’s atmosphere, as well as effects introduced by instruments and detectors.  ExTrA is currently being used to confirm TESS planet detections around M-dwarfs, refine transit parameters, and search for additional exoplanets in the same systems. ExTrA obtains a better precision for the planetary radius and for the transit timings for late M-type stars with one or a few TESS transits. This work already led to the confirmation of a mini-Neptune around the M-dwarf TOI-269 (Cointepas et al. 2021). ExTrA will also work in tandem with NIRPS, a near-infrared spectrograph that will join HARPS (High Accuracy Radial velocity Planet Searcher) on the 3.6m ESO telescope to conduct a comprehensive radial-velocity survey on M dwarfs. </p>

scholarly journals The Near Infrared FeH Lines as Indicators of Surface Gravity of M stars

1996 ◽  
Vol 171 ◽  
pp. 441-441
Author(s):  
Ricardo Piorno Schiavon ◽  
Beatriz Barbuy
Keyword(s):  
Near Infrared ◽  
Synthesis Method ◽  
Population Synthesis ◽  
Atmospheric Parameters ◽  
M Dwarfs ◽  
Synthetic Spectra ◽  
Iron Hydride ◽  
M Stars ◽  
M Dwarf ◽  
Ongoing Project

We compute synthetic spectra in the region around 1 μm, including the Wing-Ford band (WFB) of Iron Hydride (FeH) in the calculations. This band is known to be a good indicator of surface gravities of M stars. Employing Kurucz model atmospheres, we study the response of the intensity of the WFB to atmospheric parameters and check our results against observations of M dwarfs. This study is part of an ongoing project which aims to investigate the M dwarf-to-giant ratio in galaxies, through a population synthesis method, exploring a number of spectral indicators in the near infrared, such as the WFB, the NaI, CaII and CO near infrared features.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2020 ◽  
Vol 640 ◽  
pp. A50 ◽  
Author(s):  
F. F. Bauer ◽  
M. Zechmeister ◽  
A. Kaminski ◽  
C. Rodríguez López ◽  
J. A. Caballero ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Near Infrared ◽  
Work Flow ◽  
M Dwarfs ◽  
Dual Channel ◽  
Infrared Channel

The high-resolution, dual channel, visible and near-infrared spectrograph CARMENES offers exciting opportunities for stellar and exoplanetary research on M dwarfs. In this work we address the challenge of reaching the highest radial velocity precision possible with a complex, actively cooled, cryogenic instrument, such as the near-infrared channel. We describe the performance of the instrument and the work flow used to derive precise Doppler measurements from the spectra. The capability of both CARMENES channels to detect small exoplanets is demonstrated with the example of the nearby M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth (4.0 ± 0.4 M⊕) companion on a 2.29 d orbit.

scholarly journals CARMENES: M dwarfs and their planets

2015 ◽  
Vol 11 (S320) ◽  
pp. 388-390
Author(s):  
A. Quirrenbach ◽  
P.J. Amado ◽  
J.A. Caballero ◽  
H. Mandel ◽  
R. Mundt ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Spectral Resolution ◽  
M Dwarfs ◽  
Habitable Zones ◽  
Scientific Goal ◽  
New Instrument ◽  
Fabry Perot ◽  
Calar Alto ◽  
Sufficient Precision

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a new instrument currently undergoing commissioning at the 3.5 m telescope of the Calar Alto Observatory. It has been constructed by a consortium of eleven Spanish and German institutions. The scientific goal of the project is a 600-night radial-velocity survey targeting 300 M dwarfs with sufficient precision to detect terrestrial planets in their habitable zones. The CARMENES instrument consists of two separate échelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. Both spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a long-term radial velocity precision of 1 m s−1. The wavelength calibration will be done with Th-Ne and U-Ne emission line lamps, and with Fabry-Pérot etalons.

scholarly journals Search for Low-Mass Planets Around Late-M Dwarfs Using IRD

2012 ◽  
Vol 8 (S293) ◽  
pp. 201-203
Author(s):  
Masashi Omiya ◽  
Bun'ei Sato ◽  
Hiroki Harakawa ◽  
Masayuki Kuzuhara ◽  
Teruyuki Hirano ◽  
...  
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Near Infrared ◽  
Frequency Comb ◽  
Habitable Zone ◽  
Velocity Measurements ◽  
M Dwarfs ◽  
Low Mass ◽  
Rocky Planets ◽  
Theoretical Simulations

AbstractWe have a plan to conduct a Doppler planet search for low-mass planets around nearby middle-to-late M dwarfs using IRD. IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. We expect to achieve the accuracy of the radial velocity measurements of 1 m/s using IRD with a frequency comb as a wavelengh calibrator. Thus, we would detect super-Earths in habitable zone and low-mass rocky planets in close-in orbits around late-M dwarfs. In this survey, we aim to understand and discuss statistical properties of low-mass planets around low-mass M dwarfs compared with those derived from theoretical simulations.

scholarly journals Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System

2021 ◽  
Vol 162 (6) ◽  
pp. 295
Author(s):  
Bryson L. Cale ◽  
Michael Reefe ◽  
Peter Plavchan ◽  
Angelle Tanner ◽  
Eric Gaidos ◽  
...  
Keyword(s):  
Process Model ◽  
Near Infrared ◽  
Wavelength Dependence ◽  
M Dwarfs ◽  
Echelle Spectrograph ◽  
Stellar Activity ◽  
Transiting Planets ◽  
Order Of Magnitude ◽  
Modeling Toolkit ◽  
M Dwarf

Abstract We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early-M dwarf known to host two transiting planets—P b ∼ 8.46 days, R b = 4.38 − 0.18 + 0.18 R ⊕ , P c ∼ 18.86 days, R c = 3.51 − 0.16 + 0.16 R ⊕ . With visible RVs from Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical echelle Spectrographs (CARMENES)-VIS, CHIRON, HARPS, HIRES, Minerva-Australis, and Tillinghast Reflector Echelle Spectrograph, as well as near-infrared (NIR) RVs from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou, we provide a 5σ upper limit to the mass of AU Mic c of M c ≤ 20.13 M ⊕ and present a refined mass of AU Mic b of M b = 20.12 − 1.57 + 1.72 M ⊕ . Used in our analyses is a new RV modeling toolkit to exploit the wavelength dependence of stellar activity present in our RVs via wavelength-dependent Gaussian processes. By obtaining near-simultaneous visible and near-infrared RVs, we also compute the temporal evolution of RV “color” and introduce a regressional method to aid in isolating Keplerian from stellar activity signals when modeling RVs in future works. Using a multiwavelength Gaussian process model, we demonstrate the ability to recover injected planets at 5σ significance with semi-amplitudes down to ≈10 m s−1 with a known ephemeris, more than an order of magnitude below the stellar activity amplitude. However, we find that the accuracy of the recovered semi-amplitudes is ∼50% for such signals with our model.

scholarly journals Precision Radial Velocities in the Near Infrared with TEDI

2008 ◽  
Vol 4 (S253) ◽  
pp. 157-161 ◽  
Author(s):  
James P. Lloyd ◽  
Agnieszka Czeszumska ◽  
Jerry Edelstein ◽  
David Erskine ◽  
Michael Feuerstein ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Habitable Zones ◽  
Low Mass ◽  
Transit Method

AbstractThe TEDI (TripleSpec - Exoplanet Discovery Instrument) is a dedicated instrument for the near-infrared radial velocity search for planetary companions to low-mass stars with the goal of achieving meters-per-second radial velocity precision. Heretofore, such planet searches have been limited almost entirely to the optical band and to stars that are bright in this band. Consequently, knowledge about planetary companions to the populous but visibly faint low-mass stars is limited. In addition to the opportunity afforded by precision radial velocity searches directly for planets around low mass stars, transits around the smallest M dwarfs offer a chance to detect the smallest possible planets in the habitable zones of the parent stars. As has been the the case with followup of planet candidates detected by the transit method requiring radial velocity confirmation, the capability to undertake efficient precision radial velocity measurements of mid-late M dwarfs will be required. TEDI has been commissioned on the Palomar 200” telescope in December 2007, and is currently in a science verification phase.

scholarly journals New disk discovered with VLT/SPHERE around the M star GSC 07396−00759

2018 ◽  
Vol 613 ◽  
pp. L6 ◽  
Author(s):  
E. Sissa ◽  
J. Olofsson ◽  
A. Vigan ◽  
J. C. Augereau ◽  
V. D’Orazi ◽  
...  
Keyword(s):  
Near Infrared ◽  
Scattered Light ◽  
Debris Disks ◽  
M Dwarfs ◽  
Infrared Excess ◽  
Asymmetric Structures ◽  
High Resolution Imagery ◽  
Low Mass ◽  
Dust Dynamics ◽  
M Dwarf

Debris disks are usually detected through the infrared excess over the photospheric level of their host star. The most favorable stars for disk detection are those with spectral types between A and K, while the statistics for debris disks detected around low-mass M-type stars is very low, either because they are rare or because they are more difficult to detect. Terrestrial planets, on the other hand, may be common around M-type stars. Here, we report on the discovery of an extended (likely) debris disk around the M-dwarf GSC 07396−00759. The star is a wide companion of the close accreting binary V4046 Sgr. The system probably is a member of the β Pictoris Moving Group. We resolve the disk in scattered light, exploiting high-contrast, high-resolution imagery with the two near-infrared subsystems of the VLT/SPHERE instrument, operating in the Y J bands and the H2H3 doublet. The disk is clearly detected up to 1.5′′ (~110 au) from the star and appears as a ring, with an inclination i ~ 83°, and a peak density position at ~70 au. The spatial extension of the disk suggests that the dust dynamics is affected by a strong stellar wind, showing similarities with the AU Mic system that has also been resolved with SPHERE. The images show faint asymmetric structures at the widest separation in the northwest side. We also set an upper limit for the presence of giant planets to 2 MJ. Finally, we note that the 2 resolved disks around M-type stars of 30 such stars observed with SPHERE are viewed close to edge-on, suggesting that a significant population of debris disks around M dwarfs could remain undetected because of an unfavorable orientation.

scholarly journals Optical and Near-infrared Radial Velocity Content of M Dwarfs: Testing Models with Barnard’s Star

2018 ◽  
Vol 155 (5) ◽  
pp. 198 ◽  
Author(s):  
Étienne Artigau ◽  
Lison Malo ◽  
René Doyon ◽  
Pedro Figueira ◽  
Xavier Delfosse ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
M Dwarfs

scholarly journals Radial velocity information content of M dwarf spectra in the near-infrared

2016 ◽  
Vol 586 ◽  
pp. A101 ◽  
Author(s):  
P. Figueira ◽  
V. Zh. Adibekyan ◽  
M. Oshagh ◽  
J. J. Neal ◽  
B. Rojas-Ayala ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Information Content ◽  
Near Infrared ◽  
Velocity Information ◽  
M Dwarf

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 615 ◽  
pp. A6 ◽  
Author(s):  
V. M. Passegger ◽  
A. Reiners ◽  
S. V. Jeffers ◽  
S. Wende-von Berg ◽  
P. Schöfer ◽  
...  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Stellar Atmosphere ◽  
Stellar Atmospheres ◽  
Surface Gravity ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Target Sample ◽  
M Dwarf ◽  
The Phoenix

Context. The new CARMENES instrument comprises two high-resolution and high-stability spectrographs that are used to search for habitable planets around M dwarfs in the visible and near-infrared regime via the Doppler technique. Aims. Characterising our target sample is important for constraining the physical properties of any planetary systems that are detected. The aim of this paper is to determine the fundamental stellar parameters of the CARMENES M-dwarf target sample from high-resolution spectra observed with CARMENES. We also include several M-dwarf spectra observed with other high-resolution spectrographs, that is CAFE, FEROS, and HRS, for completeness. Methods. We used a χ2 method to derive the stellar parameters effective temperature Teff, surface gravity logg, and metallicity [Fe/H] of the target stars by fitting the most recent version of the PHOENIX-ACES models to high-resolution spectroscopic data. These stellar atmosphere models incorporate a new equation of state to describe spectral features of low-temperature stellar atmospheres. Since Teff, logg, and [Fe/H] show degeneracies, the surface gravity is determined independently using stellar evolutionary models. Results. We derive the stellar parameters for a total of 300 stars. The fits achieve very good agreement between the PHOENIX models and observed spectra. We estimate that our method provides parameters with uncertainties of σTeff = 51 K, σlog g = 0.07, and σ[Fe/H] = 0.16, and show that atmosphere models for low-mass stars have significantly improved in the last years. Our work also provides an independent test of the new PHOENIX-ACES models, and a comparison for other methods using low-resolution spectra. In particular, our effective temperatures agree well with literature values, while metallicities determined with our method exhibit a larger spread when compared to literature results.

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