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Acoustic waves in M dwarfs: Maintaining a coronaWe use a time-dependent hydrodynamics code to follow the propagation of acoustic waves into the corona of an M dwarf star. An important qualitative difference between M dwarfs and stars such as the Sun is that the acoustic spectrum in M dwarfs is expected to peak at periods close to the acoustic cutoff P(sub A): this allows more effective penetration of waves into the corona. In our code, radiative losses in the photosphere, chromosphere, and corona are computed using Rosseland mean opacities, Mg II kappa and Ly alpha emission, and optically thin emissivities respectively. We find that acoustic heating can maintain a corona with a temperature of order 0.7-1 x 10(exp 6) K and a surface X-ray flux as large as 10(exp 5)ergs/sq cm/s. In a recent survey of X-rays from M dwarfs, some (20%-30%) of the stars lie at or below this limiting X-ray flux: we suggest that such stars may be candidates for acoustically maintained coronae.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Mullan, D. J.
(Univ. of Delaware, Newark, DE United States)
Cheng, Q. Q.
(Univ. of Delaware, Newark, DE United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 420
Issue: 1
ISSN: 0004-637X
Subject Category
Accession Number
Funding Number(s)
Distribution Limits

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