Stellar Radio Astronomy: Probing Stellar Atmospheres from Protostars to Giants

By M. Güdel. 2002

272 citations recorded by the source corpus.

▪ Abstract Radio astronomy has provided evidence for the presence of ionized atmospheres around almost all classes of nondegenerate stars. Magnetically confined coronae dominate in the cool half of the Hertzsprung-Russell diagram. Their radio emission is predominantly of nonthermal origin and has been identified as gyrosynchrotron radiation from mildly relativistic electrons, apart from some coherent emission mechanisms. Ionized winds are found in hot stars and in red giants. They are detected through their thermal, optically thick radiation, but synchrotron emission has been found in many systems as well. The latter is emitted presumably by shock-accelerated electrons in weak magnetic fields in the outer wind regions. Radio emission is also frequently detected in pre–main sequence stars and protostars and has recently been discovered in brown dwarfs. This review summarizes the radio view of the atmospheres of nondegenerate stars, focusing on energy release physics in cool coronal stars, wind phenomenolog...

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Large dust particles in disks around T Tauri stars (2005, background): “Radio emission from low-mass pre-main-sequence stars is a common phenomenon (Güdel 2002).”
Observations of Cool-Star Magnetic Fields (2012, background): “Radio emission can be generated by different processes leading to characteristic signatures of radio emission; for an overview see Güdel (2002).”
EMU: Evolutionary Map of the Universe (2011, background): “The strongest radio emissions appear to be associated with mass loss and magnetic phenomena and are often highly variable (Güdel 2002; Dulk 1985;White 2004).”
A radio-emitting outflow in the quiescent state of A0620−00: implications for modelling low-luminosity black hole binaries (2006, background): “Note that the orbital parameters have been proven not to influence significantly the level of radio emission from magnetically active stars (Drake, Simon & Linsky 1989; see Güdel 2002 for a thourough review).”
Plasma interactions of exoplanets with their parent star and associated radio emissions (2006, background): “…galactic background luminosity, ionospheric perturbations, and intense natural and man-made radio frequency interference - or RFI), present instruments are generally limited to the detection of stellar radio bursts several orders of magnitude more intense than solar ones (see e.g. Güdel, 2002).”
Stellar Activity on the Young Suns of Orion: COUP Observations of K5-7 Pre-Main-Sequence Stars (2005, background): “Radio observations show gyrosynchrotron radiation from MeVelectrons accelerated by magnetic flares in some young stellar systems (Güdel 2002).1 Universe Division, Science Mission Directorate, NASA Headquarters.”
The Sun in Time: Activity and Environment (2007, methodology): “For summaries of stellar X-ray and radio emission, I refer to Güdel (2004) and Güdel (2002), respectively.”
THE FIRST ACCURATE PARALLAX DISTANCE TO A BLACK HOLE (2009, methodology): “The advent of the EVLA and the ongoing VLBA sensitivity upgrade will allow us to extend this method to a number of systems with fainter quiescent jets, as well as opening up the possibility of detecting gyrosynchrotron emission from low-mass donor stars (e.g., Güdel 2002).”
Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs (2008, background): “…from LSR J1835, which is generated at the fundamental and perhaps first harmonic of the plasma frequency, νp ≈ 9000n 1/2 e Hz and requires νp ≫ νc, where ne is the plasma electron density and νc is the electron cyclotron frequency in the source region (Dulk 1985; Bastian et al. 1998; Güdel 2002).”
Radio Observations of a Large Sample of Late M, L, and T Dwarfs: The Distribution of Magnetic Field Strengths (2006, background): “Following the formulation of Güdel (2002) I find that the peak frequency is given by m 1:66 ; 104n0:23e R 0:23B0:77 Hz; ð1Þ the flux density is given by F ;m 1:54 ; 10 4B 0:76R2d 2 2:76m Jy; ð2Þ the fraction of circular polarization is given by fc 2:85 ; 103B0:51 0:51m ; ð3Þ and an average angle…”