THE CORONAL ABUNDANCES OF MID-F DWARFS

Journal Article · Fri May 10 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/768/2/122· OSTI ID:22126756

Wood, Brian E.; Laming, J. Martin ^[1]

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1. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)

A Chandra spectrum of the moderately active nearby F6 V star {pi}{sup 3} Ori is used to study the coronal properties of mid-F dwarfs. We find that {pi}{sup 3} Ori's coronal emission measure distribution is very similar to those of moderately active G and K dwarfs, with an emission measure peak near log T = 6.6 seeming to be ubiquitous for such stars. In contrast to coronal temperature, coronal abundances are known to depend on spectral type for main sequence stars. Based on this previously known relation, we expected {pi}{sup 3} Ori's corona to exhibit an extremely strong ''first ionization potential (FIP) effect'', a phenomenon first identified on the Sun where elements with low FIP are enhanced in the corona. We instead find that {pi}{sup 3} Ori's corona exhibits a FIP effect essentially identical to that of the Sun and other early G dwarfs, perhaps indicating that the increase in FIP bias toward earlier spectral types stops or at least slows for F stars. We find that {pi}{sup 3} Ori's coronal characteristics are significantly different from two previously studied mid-F stars, Procyon (F5 IV-V) and {tau} Boo (F7 V). We believe {pi}{sup 3} Ori is more representative of the coronal characteristics of mid-F dwarfs, with Procyon being different because of luminosity class, and {tau} Boo being different because of the effects of one of two close companions, one stellar ({tau} Boo B: M2 V) and one planetary.

• OSTI ID: 22126756
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 768; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
DISTRIBUTION
EMISSION
IONIZATION POTENTIAL
LUMINOSITY
SPECTRA
SUN
X RADIATION