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The Na I D resonance lines in main sequence late-type stars
- Source :
- Mon.Not.Roy.Astron.Soc.378:1007-1018,2007
- Publication Year :
- 2007
-
Abstract
- We study the sodium D lines (D1: 5895.92 \AA; D2: 5889.95 \AA) in late-type dwarf stars. The stars have spectral types between F6 and M5.5 (B-V between 0.457 and 1.807) and metallicity between [Fe/H] = -0.82 and 0.6. We obtained medium resolution echelle spectra using the 2.15-m telescope at the argentinian observatory CASLEO. The observations have been performed periodically since 1999. The spectra were calibrated in wavelength and in flux. A definition of the pseudo-continuum level is found for all our observations. We also define a continuum level for calibration purposes. The equivalent width of the D lines is computed in detail for all our spectra and related to the colour index (B-V) of the stars. When possible, we perform a careful comparison with previous studies. Finally, we construct a spectral index (R_D') as the ratio between the flux in the D lines, and the bolometric flux. We find that, once corrected for the photospheric contribution, this index can be used as a chromospheric activity indicator in stars with a high level of activity. Additionally, we find that combining some of our results, we obtain a method to calibrate in flux stars of unknown colour.<br />Comment: 12 pages, including 14 figures and 4 tables. Accepted for publication in MNRAS
- Subjects :
- Astrophysics
Subjects
Details
- Database :
- arXiv
- Journal :
- Mon.Not.Roy.Astron.Soc.378:1007-1018,2007
- Publication Type :
- Report
- Accession number :
- edsarx.0704.0812
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1111/j.1365-2966.2007.11833.x