2021ApJ...923..192A -
Astrophys. J., 923, 192-192 (2021/December-3)
In the trenches of the solar-stellar connection. V. High-resolution ultraviolet and X-ray observations of Sun-like stars: the curious case of Procyon.
AYRES T.R.
Abstract (from CDS):
A joint X-ray (0.2-2 keV) and ultraviolet (1150-3000 Å) time-domain study has been carried out on three nearby bright late-type stars, bracketing the Sun in properties. Alpha Cen A (HD 128620: G2 V) is a near twin to the Sun, although slightly more massive and luminous, slightly metal-rich, but older. Alpha Cen B (HD 128621: K1 V) is cooler than the Sun, somewhat less massive and lower in luminosity. Procyon (HD 61421: F5 IV-V) is hotter, more massive and more luminous than the Sun, half the age, but more evolved. Stellar observations were from Chandra X-ray Observatory and Hubble Space Telescope (HST). The Sun provided a benchmark through high-energy spectral scans from solar irradiance satellites and novel high-dispersion full-disk profiles of key UV species-Mg II, C II, and Si IV-from the Interface Region Imaging Spectrograph. Procyon's flux history was strikingly constant at all wavelengths, in contrast to the other three cycling-dynamo stars. Procyon also displays a strong subcoronal (T ∼ 1 x 105 K) emission excess, relative to chromospheric Mg II (T <= 104 K), although its X-rays (T ∼ 2 MK) appear to be more normal. At the same time, the odd sub-Gaussian shapes, and redshifts, of the subgiant's "hot lines" (such as Si IV and C IV) are remarkably similar to the solar counterparts (and α Cen AB). This suggests a Sun-like origin, namely a supergranulation network supplied by magnetic flux from a noncycling "local dynamo."
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Late-type stars - Solar cycle - Solar analogs - Ultraviolet astronomy - X-ray astronomy
Simbad objects:
6
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