Abstract
Molecular FeH provides a large number of sharp and isolated absorption lines that can be used to measure radial velocity, rotation, or magnetic field strength with high accuracy. Our aim is to provide an FeH atlas for M-type stars in the spectral region from 986 nm to 1077 nm (Wing-Ford band). To identify these lines in CRIRES spectra of the magnetically inactive, slowly rotating, M5.5 dwarf GJ1002, we calculated model spectra for the selected spectral region with theoretical FeH line data. In general this line list agrees with the observed data, but several individual lines differ significantly in position or in line strength. After identification of as many as possible FeH lines, we correct the line data for position and line strength to provide an accurate atlas of FeH absorption lines for use in high precision spectroscopy of low mass stars. For all lines, we use a Voigt function to obtain their positions and equivalent widths. Identification with theoretical lines is done by hand. For confirmation of the identified lines, we use statistical methods, cross- correlation techniques, and line intensities. Eventually, we were able to identify FeH lines from the (0, 0), (1, 0), (1, 1), (2, 1), (2, 2), (3, 2), and (4, 3) vibrational bands in the observed spectra and correct the positions of the lines if necessary. The deviations between theoretical and observed positions follow a normal distribution approximately around zero. In order to empirically correct the line strength, we determined Teff, instrumental broadening (rotational broadening) and a van der Waals enhancement factor for FeH lines in GJ1002. We also give scaling factors for the Einstein A values to correct the line strengths. With the identified lines, we derived rotational temperatures from line intensities for GJ1002. ... .
Highlights
High-resolution spectroscopy of atomic or molecular lines is used to measure rotation, magnetic fields, and radial velocity variations
We identify the observed lines with theoretical ones by hand, and confirm this identification using statistical means, crosscorrelation techniques, and the line strength of the identified FeH lines
Because atomic lines are present in the wavelength region of the observed spectra of GJ1002, we use the VALD2 (Kupka et al 1999; Piskunov et al 1995) database to include the available atomic line data in our calculations
Summary
High-resolution spectroscopy of atomic or molecular lines is used to measure rotation, magnetic fields, and radial velocity variations. In solar-like stars, atomic lines are useful to measure these quantities because they are numerous, well isolated, and sufficiently narrow. Like M dwarfs, atomic lines are no longer useful because most of them become very weak, others become strongly pressure-broadened and they are usually overlapped by strong molecular bands. In these stars molecular lines are a valuable tool to measure the quantities mentioned above. A few molecules provide absorption lines that are isolated and can be used for detailed spectroscopic analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
