Coronal Temperature Distributions and Convection-Zone Depth: The F and G-type Dwarfs
Abstract
We propose to obtain coronal temperature distributions for a carefully selected sample of mid-F to mid-G type dwarfs using the EUVE spectrometers to probe the mechanisms which give rise to hot and cool coronal plasma in late-type, main-sequence stars. The five program stars chosen meet five basic criteria. They a) are single stars, b) are normal, main-sequence F5-G5 dwarfs, c) have measured rotational velocities, d) have measured parallaxes, and e) have EUVE 100A survey count rates in excess of 50 counts per kilosecond. These stars span a critical spectral range where the depth of the outer convection zone and, presumably, the level of magnetic heating increases with decreasing effective temperature. EUVE spectra provide Fe lines covering a broad range of ionization states to determine the emission measure distribution independent of coronal abundance uncertainties. While low-resolution Einstein IPC and ROSAT PSPC spectra hint at increasing coronal temperatures from mid-F to mid-G, only with high-resolution EUVE spectra can we derive the true emission measure distribution across the full range of coronal plasma temperatures.
- Publication:
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EUVE Proposal
- Pub Date:
- 1994
- Bibcode:
- 1994euve.prop...82L
- Keywords:
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- EUVE Proposal ID #94-082