CRIRES spectroscopy and empirical line-by-line identification of FeH molecular absorption in an M dwarf

Wende, S.; Reiners, A.; Seifahrt, Andreas; Bernath, P. F.

doi:10.1051/0004-6361/201015220

Cited by 82 publications

(54 citation statements)

References 22 publications

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“…In conclusion, we decided to use the BP list for the analysis. After the completion of the present paper we noted that the line list by Dulick et al (2003) has been used by Wende et al (2010) to model CRIRES spectra of a late M dwarf in the wavelength range 986-1077 nm and subsequently by Shulyak et al (2011) for a study of rotation and magnetic fields in late-type M-dwarf binaries.…”

Section: Spectral Line Datamentioning

confidence: 93%

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

Önehag

Heiter

Gustafsson

et al. 2012

A&A

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Context. The relatively wide spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approacheshave not yet converged to consistency. The presence of strong molecular features and incomplete line lists for the corresponding molecules have made determining the metallicity of M dwarfs difficult. Furthermore, the faint M dwarfs require long exposure times for the signalto-noise ratio needed for a detailed spectroscopic abundance analysis. Aims. We present a high-resolution (R ∼ 50 000) spectroscopic study of a sample of eight single M dwarfs and three wide-binary systems observed in the infrared J band. Methods. The absence of large molecular contributions allows for a precise continuum placement. We derived metallicities based on the best fit of synthetic spectra to the observed spectra. To verify the accuracy of the applied atmospheric models and test our synthetic spectrum approach, three binary systems with a K-dwarf primary and an M-dwarf companion were observed and analysed along with the single M dwarfs. Results. We obtain good agreement between the metallicities derived for the primaries and secondaries of our test binaries, thereby confirming the reliability of our method of analysing M dwarfs. Our metallicities agree well with some earlier determinations, and deviate from others. Conclusions. We conclude that spectroscopic abundance analysis in the J band is a reliable method for establishing the metallicity scale for M dwarfs. We recommend its application to a larger sample covering lower, as well as higher, metallicities. Further prospects for the method include abundance determinations for individual elements.

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Section: Spectral Line Datamentioning

confidence: 93%

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

Önehag

Heiter

Gustafsson

et al. 2012

A&A

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“…Transition probabilities for some of these lines were corrected according to Wende et al (2010). Transition parameters for atomic lines were extracted from the VALD database (Piskunov et al 1995;Kupka et al 1999).…”

Section: Methodsmentioning

confidence: 99%

Exploring the magnetic field complexity in M dwarfs at the boundary to full convection

Shulyak

Reiners

Seemann

et al. 2014

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Context. Magnetic fields play a pivotal role in the formation and evolution of low-mass stars, but the dynamo mechanisms generating these fields are poorly understood. Measuring cool star magnetism is a complicated task because of the complexity of cool star spectra and the subtle signatures of magnetic fields. Aims. Based on detailed spectral synthesis, we carry out quantitative measurements of the strength and complexity of surface magnetic fields in the four well-known M dwarfs GJ 388, GJ 729, GJ 285, and GJ 406 that populate the mass regime around the boundary between partially and fully convective stars. Very high-resolution (R = 100 000), high signal-to-noise (up to 400), near-infrared Stokes I spectra were obtained with CRIRES at ESO's Very Large Telescope covering regions of the FeH Wing-Ford transitions at 1 μm and Na i lines at 2.2 μm.Methods. A modified version of the Molecular Zeeman Library (MZL) was used to compute Landé g-factors for FeH lines. We determined the distribution of magnetic fields by magnetic spectral synthesis performed with the Synmast code. We tested two different magnetic geometries to probe the influence of field orientation effects. Results. Our analysis confirms that FeH lines are excellent indicators of surface magnetic fields in low-mass stars of type M, particularly in comparison to profiles of Na i lines that are heavily affected by water lines and that suffer problems with continuum normalization. The field distributions in all four stars are characterized by three distinct groups of field components, and the data are consistent neither with a smooth distribution of different field strengths nor with one average field strength covering the full star. We find evidence of a subtle difference in the field distribution of GJ 285 compared to the other three targets. GJ 285 also has the highest average field of 3.5 kG and the strongest maximum field component of 7-7.5 kG. The maximum local field strengths in our sample seem to be correlated with rotation rate. While the average field strength is saturated, the maximum local field strengths in our sample show no evidence of saturation. Conclusions. We find no difference between the field distributions of partially and fully convective stars. The one star with evidence of field distribution different from the other three is the most active star (i.e. with X-ray luminosity and mean surface magnetic field) rotating relatively fast. A possible explanation is that rotation determines the distribution of surface magnetic fields, and that local field strengths grow with rotation even in stars in which the average field is already saturated.

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“…In our investigation we employed the FeH line list of the Wing–Ford band ( F 4 Δ− X 4 Δ transitions at 1 μm) and molecular constants taken from Dulick et al (2003) 1 . For some of these lines, we used corrected Einstein A values according to Wende et al (2010).…”

Section: Methodsmentioning

confidence: 99%

“…We then mapped all 1D spectra on to a common wavelength grid and finally co‐added all rebinned spectra of each component. The wavelength solutions are based at first order on the ThAr calibration frames provided by European Southern Observatory (ESO) and were refined by matching the science spectra to the atlas of GJ 1002, previously observed with CRIRES (Wende et al 2010).…”

Section: Observationsmentioning

confidence: 99%

Rotation, magnetism and metallicity of M dwarf systems★

Shulyak¹,

Seifahrt²,

Reiners³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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Close M dwarf binaries and higher multiples allow the investigation of rotational evolution and mean magnetic flux unbiased from scatter in inclination angle and age since the orientation of the spin axis of the components is most likely parallel and the individual systems are coeval. Systems composed of an early‐type (M0.0–M4.0) and a late‐type (M4.0–M8.0) component offer the possibility to study differences in rotation and magnetism between partially and fully convective stars. We have selected 10 of the closest dM systems to determine the rotation velocities and the mean magnetic field strengths based on spectroscopic analysis of FeH lines of Wing–Ford transitions at 1 μm observed with Very Large Telescope/CRIRES. We also studied the quality of our spectroscopic model regarding atmospheric parameters including metallicity. A modified version of the Molecular Zeeman Library (MZL) was used to compute Landég‐factors for FeH lines. Magnetic spectral synthesis was performed with the synmast code. We confirmed previously reported findings that less massive M dwarfs are braked less effectively than objects of earlier types. Strong surface magnetic fields were detected in primaries of four systems (GJ 852, GJ 234, LP 717−36 and GJ 3322), and in the secondary of the triple system GJ 852. We also confirm strong 2‐kG magnetic field in the primary of the triple system GJ 2005. No fields could be accurately determined in rapidly rotating stars with υ sin i > 10 km s−1. For slowly and moderately rotating stars, we find the surface magnetic field strength to increase with the rotational velocity υ sin i which is consistent with other results from studying field stars.

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CRIRES spectroscopy and empirical line-by-line identification of FeH molecular absorption in an M dwarf

Cited by 82 publications

References 22 publications

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

M-dwarf metallicities. A high-resolution spectroscopic study in the near infrared

Exploring the magnetic field complexity in M dwarfs at the boundary to full convection

Rotation, magnetism and metallicity of M dwarf systems★

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