Physical parameters of a sample of M dwarfs from high-resolution near-infrared spectra

Context. Being the most numerous and oldest stars in the galaxy, M dwarfs are objects of great interest for exoplanet searches. The presence of molecules in their atmosphere complicates our understanding of their atmospheric properties. But great advances have recently been made in the modeling of M dwarfs due to the revision of solar abundances. Aims. We aim to determine stellar parameters of M dwarfs using high resolution spectra (R ∼ 90 000) simultaneously in the visible and the near-infrared. The high resolution spectra and broad wavelength coverage provide an unique opportunity to understand the onset of dust and cloud formation at cool temperatures. Furthermore, this study will help in understanding the physical processes which occur in a cool atmospheres, particularly, the redistribution of energy from the optical to the near-infrared. Methods. The stellar parameters of M dwarfs in our sample have been determined by comparing the high resolution spectra both in the optical and in the near-infrared simultaneously observed by CARMENES with the synthetic spectra obtained from the BT-Settl model atmosphere. The detailed spectral synthesis of these observed spectra both in the optical and in the near-infrared helps to understand the missing continuum opacity. Results. For the first time, we derive fundamental stellar parameters of M dwarfs using the high resolution optical and near-infrared spectra simultaneously. We determine Teff, log g and [M/H] for 292 M dwarfs of spectral type M0 to M9, where the formation of dust and clouds are important. The derived Teff for the sample ranges from 2300 to 4000 K, values of log g ranges from 4.5 ≤ logg ≤ 5.5 and the resulting metallicity ranges from −0.5 ≤ [M/H] ≤ +0.5. We have also explored the possible differences in Teff, log g and [M/H] by comparing them with other studies of the same sample of M dwarfs.

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High-Resolution Near-Infrared Spectra of Protostars

The Astronomical Journal ◽

10.1086/301452 ◽

2000 ◽

Vol 120 (1) ◽

pp. 430-436 ◽

Cited By ~ 13

Author(s):

Thomas P. Greene ◽

Charles J. Lada

Keyword(s):

High Resolution ◽

Infrared Spectra ◽

Near Infrared ◽

Near Infrared Spectra

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High-resolution near-infrared spectra of NGC 6624 and 6569★

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2011.18580.x ◽

2011 ◽

Vol 414 (3) ◽

pp. 2690-2695 ◽

Cited By ~ 30

Author(s):

E. Valenti ◽

L. Origlia ◽

R. M. Rich

Keyword(s):

High Resolution ◽

Infrared Spectra ◽

Near Infrared ◽

Near Infrared Spectra

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Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Verification by binary systems

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psaa101 ◽

2020 ◽

Vol 72 (6) ◽

Author(s):

Hiroyuki Tako Ishikawa ◽

Wako Aoki ◽

Takayuki Kotani ◽

Masayuki Kuzuhara ◽

Masashi Omiya ◽

...

Keyword(s):

High Resolution ◽

Measurement Errors ◽

Binary Systems ◽

Near Infrared ◽

M Dwarfs ◽

Chemical Abundances ◽

Elemental Abundances ◽

Analysis Process ◽

Near Infrared Spectra ◽

Atomic Lines

ABSTRACT M dwarfs are prominent targets of planet search projects, and their chemical composition is crucial to understanding the formation process or interior of orbiting exoplanets. However, measurements of elemental abundances of M dwarfs have been limited due to difficulties in the analysis of their optical spectra. We conducted a detailed chemical analysis of five M dwarfs (Teff ∼ 3200–3800 K), which form binary systems with G/K-type stars, by performing a line-by-line analysis based on high-resolution (R ∼ 80000) near-infrared (960–1710 nm) spectra obtained with CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Échelle Spectrographs). We determined the chemical abundances of eight elements (Na, Mg, K, Ca, Ti, Cr, Mn, and Fe), which are in agreement with those of the primary stars within measurement errors (∼0.2 dex). Through the analysis process, we investigated the unique behavior of atomic lines in a cool atmosphere. Most atomic lines are sensitive to changes in the abundance of not only the corresponding elements but also other elements, especially dominant electron donors such as Na and Ca. The Ti i lines show a negative correlation with the overall metallicity at Teff < 3400 K due to the consumption of neutral titanium by the formation of TiO molecules. These findings indicate that to estimate the overall metallicity or the abundance of any element correctly, we need to determine the abundances of other individual elements consistently.

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Characterizing stellar parameters from high-resolution spectra of main sequence cool stars. I. The G2V–K2V stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1270 ◽

2019 ◽

Vol 487 (1) ◽

pp. 1335-1362

Author(s):

Logithan Kulenthirarajah ◽

Jean-François Donati ◽

Gaitee Hussain ◽

Julien Morin ◽

France Allard

Keyword(s):

High Resolution ◽

Main Sequence ◽

Near Infrared ◽

Absolute Accuracy ◽

Spectral Library ◽

M Dwarfs ◽

Near Infrared Spectra ◽

Cool Stars ◽

Error Bars ◽

Good Agreement

Abstract The goal of the present study is to construct, test, and validate a high-resolution synthetic spectral library using PHOENIX model atmospheres and develop a reliable tool to estimate stellar parameters from high-resolution optical and/or near-infrared spectra of M dwarfs. We report here the preliminary results of tests characterizing main sequence G–K stars from high-resolution spectra. We anchored the atomic line-list using the stellar standards Sun, ξ Boo A, and ϵ Eri to ensure the synthetic spectra computed with PHOENIX reproduce their observed counterparts. These stars were chosen because their parameters are very well characterized, and on which the absolute accuracy of our method depends on. We successfully estimated the stellar parameters with associated error bars for 17 stars. Using a pseudo Monte Carlo statistical analysis, we present overall improved uncertainties on the stellar parameters compared to those in the literature (on average 9 K, 0.014 dex, and 0.008 dex for the effective temperature, the surface gravity, and the metallicity, respectively). Our estimated stellar parameters are also in good agreement with values found in the literature.

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Evolution of Brown Dwarf Atmospheres: Investigating Physical Parameters from Near-IR Spectra

Symposium - International Astronomical Union ◽

10.1017/s0074180900211030 ◽

2003 ◽

Vol 211 ◽

pp. 417-418

Author(s):

Nadya Gorlova ◽

Michael R. Meyer ◽

Jim Liebert ◽

George H. Rieke

Keyword(s):

Ir Spectra ◽

Infrared Spectra ◽

Near Infrared ◽

Surface Gravity ◽

Physical Parameters ◽

Brown Dwarf ◽

Near Ir ◽

Near Infrared Spectra ◽

Low Mass

We obtained near–infrared spectra of a sample of very low mass objects as a function of age in order to investigate the temperature and surface gravity sensitivity of several features in the J– and K–bands.

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