Coronal activity in F-, G-, and K-type stars. III. The coronal differential emission measure distribution of Capella, Sigma-squared CrB, and Procyon

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/167508· OSTI ID:5643474

Lemen, J R; Mewe, R; Schrijver, C J; Fludra, A ^[1]; Wroclaw, Uniwersytet ^[2]

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1. Lockheed Research Laboratories, Palo Alto, CA (USA)
2. Poland

EXOSAT soft X-ray spectra of three binary systems of cool stars are analyzed: Capella (G6 III + F9 III), Sigma-squared CrB (F8 V + G1 V), and Procyon (F5 IV-V + DF). The EXOSAT transmission grating spectrometer permits the study of individual spectral lines and line complexes between 10 and 200 A with approximately 3 A resolution. First it is demonstrated that the spectra can be described reasonably well by a two-temperature model corona. Then the assumption that only two temperatures exist in the stellar coronas is relaxed and differential emission measure distributions are derived from the three spectra. The results from the multithermal modeling are consistent with those of the two-temperature models: emission from the coronas of each of the three stars is dominated by plasma in two relative narrow temperature intervals. These intervals are centered on 5 MK and 25 MK in the cases of Capella and Sigma-squared CrB, and 0.6 MK and 3 MK in the case of Procyon. The implications of the results for the structure of stellar coronas are briefly discussed. 41 refs.

• OSTI ID: 5643474
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 341; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BINARY STARS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MORPHOLOGY
RADIATIONS
SATELLITES
SOFT X RADIATION
SPECTRA
SPECTROMETERS
SPECTROSCOPY
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
X RADIATION
X-RAY SPECTRA