Flare stars at radio wavelengths

Conference · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6720157

Lang, K R

The radio emission from dMe flare stars is discussed using Very Large Array and Arecibo observations as examples. Active flare stars emit weak, unpolarized, quiescent radio radiation that may be always present. Although thermal bremsstrahlung and/or thermal gyroresonance radiation account for the slowly-varying, quiescent radio radiation of solar active regions, these processes cannot account for the long-wavelength quiescent radiation observed from nearby dMe flare stars. It has been attributed to nonthermal gyrosynchrotron radiation, but some as yet unexplained mechanism must be continually producing the energetic electrons. Long duration, narrow-band radiation is also emitted from some nearby dMe stars at 20 cm wavelength. Such radiation may be attributed to coherent plasma radiation or to coherent electron-cyclotron masers. Impulsive stellar flares exhibit rapid variations that require radio sources that are smaller than the star in size, and high brightness temperatures greater than 10(exp 15) K that are also explained by coherent radiation processes. Quasi-periodic temporal fluctuations suggest pulsations during some radio flares. Evidence for frequency structure and positive or negative frequency drifts during radio flares from dMe stars is also presented.

• Research Organization: Tufts Univ., Medford, MA (USA)
• OSTI ID: 6720157
• Report Number(s): N-90-21719; NASA-CR--186539; NAS--1.26:186539; CONF-8910431--
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
BRIGHTNESS
COHERENT RADIATION
DATA
ELECTROMAGNETIC RADIATION
FLUID FLOW
INFORMATION
NUMERICAL DATA
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLASMA
RADIATIONS
RADIOWAVE RADIATION
STELLAR ACTIVITY
STELLAR FLARES
THEORETICAL DATA
UNSTEADY FLOW