THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS

Journal Article · Sun Jul 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/753/1/76· OSTI ID:22036895

Wood, Brian E; Laming, J Martin ^[1]; Karovska, Margarita ^[2]

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1. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)
2. Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)

We analyze Chandra X-ray spectra of the M0 V+M0 V binary GJ 338. As quantified by X-ray surface flux, these are the most inactive M dwarfs ever observed with X-ray grating spectroscopy. We focus on measuring coronal abundances, in particular searching for evidence of abundance anomalies related to first ionization potential (FIP). In the solar corona and wind, low-FIP elements are overabundant, which is the so-called FIP effect. For other stars, particularly very active ones, an 'inverse FIP effect' is often observed, with low-FIP elements being underabundant. For both members of the GJ 338 binary, we find evidence for a modest inverse FIP effect, consistent with expectations from a previously reported correlation between spectral type and FIP bias. This amounts to strong evidence that all M dwarfs should exhibit the inverse FIP effect phenomenon, not just the active ones. We take the first step toward modeling the inverse FIP phenomenon in M dwarfs, building on past work that has demonstrated that MHD waves coursing through coronal loops can lead to a ponderomotive force that fractionates elements in a manner consistent with the FIP effect. We demonstrate that in certain circumstances this model can also lead to an inverse FIP effect, pointing the way to more detailed modeling of M dwarf coronal abundances in the future.

• OSTI ID: 22036895
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 753; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ASTRONOMY
ASTROPHYSICS
BINARY STARS
COMPUTERIZED SIMULATION
CORRELATIONS
DWARF STARS
IONIZATION POTENTIAL
MAGNETOHYDRODYNAMICS
PONDEROMOTIVE FORCE
SOLAR CORONA
STELLAR WINDS
X RADIATION
X-RAY SPECTRA
X-RAY SPECTROSCOPY