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Title: THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS

Abstract

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,more » pointing the way to more detailed modeling of M dwarf coronal abundances in the future.« less

Authors:
;  [1];  [2]
  1. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)
  2. Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22036895
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 753; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 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

Citation Formats

Wood, Brian E, Laming, J Martin, and Karovska, Margarita. THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS. United States: N. p., 2012. Web. doi:10.1088/0004-637X/753/1/76.
Wood, Brian E, Laming, J Martin, & Karovska, Margarita. THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS. United States. https://doi.org/10.1088/0004-637X/753/1/76
Wood, Brian E, Laming, J Martin, and Karovska, Margarita. 2012. "THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS". United States. https://doi.org/10.1088/0004-637X/753/1/76.
@article{osti_22036895,
title = {THE CORONAL ABUNDANCE ANOMALIES OF M DWARFS},
author = {Wood, Brian E and Laming, J Martin and Karovska, Margarita},
abstractNote = {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.},
doi = {10.1088/0004-637X/753/1/76},
url = {https://www.osti.gov/biblio/22036895}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 753,
place = {United States},
year = {Sun Jul 01 00:00:00 EDT 2012},
month = {Sun Jul 01 00:00:00 EDT 2012}
}