HST/STIS High Resolution Echelle Spectra of α Centauri A (G2 V)
Abstract
We report on HST/STIS observations of the G2 V star α Centauri A (HD 128620), a near twin to the Sun. The high resolution echelle spectra obtained with the E140H and E230H gratings cover the complete spectral range 1133--3150 Å with a resolution of 2.6 km s-1. This beautiful spectrum contains a very large number of emission and absorption lines. We present our study of the E140H spectrum. Of particular interest are the shapes of the transition region lines (e.g., Si IV, C IV), the density sensitive intersystem lines, and the He II 1640 Å line. Our purpose is to compare the α Cen A UV spectrum with the solar spectrum to determine how the atmosphere and heating processes in α Cen A differ from the Sun as a result of the small differences in gravity, age, and chemical composition of the two stars. The α Cen A spectral atlas can serve as a useful spectral atlas for the Sun as a star because the STIS spectrum is a true full disk average with limb darkening, covers a broad spectral range, has very high spectral resolution, and has excellent wavelength precision and absolute flux calibration. This work is supported by grant GO-07263 from the Space Telescope Science Institute, which is operated by AURA, Inc. under NASA contract NAS 5-26555.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AAS...201.1209L