Ultraviolet Observations of the Circumstellar Envelope of ALPHA-1-HERCULIS in the Line-Of of ALPHA-2-HERCULIS

Details Ultraviolet Observations of the Circumstellar Envelope of ALPHA-1-HERCULIS in the Line-Of of ALPHA-2-HERCULIS Ultraviolet Observations of the Circumstellar Envelope of ALPHA-1-HERCULIS in the Line-Of of ALPHA-2-HERCULIS

Jul 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993a%26a...274..838t&link_type=abstract

Astronomy and Astrophysics, Vol. 274, NO. 3/JUL(III), P. 838, 1993

Astronomy and Astrophysics

Astrophysics

8

Circumstellar Matter, Stars: Distances, Stars: Fundamental Parameters, Stars: Individual: Α Her, Stars: Mass-Loss, Ultraviolet: Stars

Scientific paper

We establish an empirical model of the circumstellar envelope of the red giant α1 Her, using spectroscopic UV and optical observations of its visual binary companion α2 Her. In particular, we obtained high-resolution IUE long wavelength spectra of α2 Her, in which for the first time α1 Her could be excluded.
The circumstellar lines along the line of sight to α2 Her are used to conduct curve-of-growth analyses, explicitly including the wind velocity field. The new UV-data of Cr, Fe, Mn, and Ni give a total mass loss rate of Mṡ = (1.5±0.3) × 1O-7 Msun yr-1, which agrees well with the value of Reimers (1977, Mṡ = 1.1 × 1O-7 Msun yr-1), determined from visible wavelengths Ti II data, and with Mauron & Caux's (1992) value of 1O-7 Msun yr-1, determined from K I and Na I scattering observations.
With curve-of-growth fits to the UV data and to the optical data from Reimers (1977), we derive ionization ratios for Ca, Cr, Fe, Mg, Ni, and Si.
By comparing the continuum stellar fluxes in the lUE spectra to theoretical models from Kurucz (1979), we determine an effective temperature of 7350 K±150 K(=^ A9) for α2 Her B and a spectral type of G8 III for α2 Her A. With the assumption that α2 Her B is a main sequence star we find a distance of about 70 Pc.
We use the resulting stellar radiation fields for an analysis of the ionization structure in the envelope of α1 Her.

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