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VLA observations of dwarf M flare stars and magnetic starsThe VLA has been used to search for 6 cm emission from 16 nearby dwarf M stars, leading to the detection of only one of them - Gliese 735. The dwarf M flare stars AD Leonis and YZ Canis Minoris were also monitored at 6 cm and 20 cm wavelength in order to study variability. Successive oppositely circularly polarized bursts were detected from AD Leo at 6 cm, suggesting the presence of magnetic fields of both magnetic polarities. An impulsive 20-cm burst from YZ CMi preceded slowly varying 6-cm emission. The VLA was also used, unsuccessfully, to search for 6-cm emission from 13 magnetic Ap stars, all of which exhibit kG magnetic fields. Although the Ap magnetic stars have strong dipolar magnetic fields, the failure to detect gyroresonant radiation suggests that these stars do not have hot, dense coronae. The quiescent microwave emission from GL 735 is probably due to nonthermal radiation, since unusually high (H = 50 kG or greater) surface magnetic fields are inferred under the assumption that the 6-cm radiation is the gyroresonant radiation of thermal electrons.
Document ID
19880059377
Document Type
Reprint (Version printed in journal)
Authors
Willson, R. F. (Tufts Univ. Medford, MA, United States)
Lang, K. R. (Tufts Univ. Medford, MA, United States)
Foster, P. (Tufts University Medford, MA, United States)
Date Acquired
August 13, 2013
Publication Date
June 1, 1988
Publication Information
Publication: Astronomy and Astrophysics
Volume: 199
Issue: 1-2
ISSN: 0004-6361
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAG5-477
CONTRACT_GRANT: N00014-86-K-0068
CONTRACT_GRANT: AF-AFOSR-83-0019
Distribution Limits
Public
Copyright
Other