Radio Emission From Solar Flares

Bastian, T. S.; Benz, A. O.; Gary, Dale E.

doi:10.1146/annurev.astro.36.1.131

Cited by 588 publications

(440 citation statements)

References 215 publications

(212 reference statements)

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“…Interestingly, this energy release is several times larger than for the brightest solar flares. 18 From the flare model we also find that the best-fit quiescent flux density is 100 ± 35 µJy, and that the probability of no quiescent component is 2 × 10 −4 . This result serves to bolster our claim that we detected quiescent emission at a level of 100 µJy from LP944−20.…”

mentioning

confidence: 62%

Discovery of radio emission from the brown dwarf LP944-20

Berger

Ball

Becker

et al. 2001

Nature

210

169

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Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. 1 Old (>10 Myr) brown dwarfs are expected to possess short-lived magnetic fields 2 and, since they no longer generate energy from collapse and accretion, weak radio and X-ray emitting coronae. Several efforts have been undertaken in the past to detect chromospheric activity from the brown dwarf LP944−20 at X-ray 1,3 and optical 4,5,6,7 wavelengths, but only recently an X-ray flare from this object was detected. 3 Here we report on the discovery of quiescent and flaring radio emission from this source, which represents the first detection of persistent radio emission from a brown dwarf, with luminosities that are several orders of magnitude larger than predicted from an empirical relation 8,9 between the X-ray and radio luminosities of many stellar types. We show in the context of synchrotron emission, that LP944−20 possesses an unusually weak magnetic field in comparison to active dwarf M stars, 10,11 which might explain the null results from previous optical and X-ray observations of this source, and the deviation from the empirical relations. This paper has been submitted to Nature. You are free to use the results here for the purpose of

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mentioning

confidence: 62%

Discovery of radio emission from the brown dwarf LP944-20

Berger

Ball

Becker

et al. 2001

Nature

210

169

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“…A long list of sources may present variable and transient behavior, from stellar flares (Bastian et al 1998;Osten et al 2005), spinning neutron stars (Hewish et al 1968;Camilo et al 2006), and gamma-ray bursts (GRB; Klebesadel et al 1973;Dessenne et al 1996), to yet-detected extra-solar planets (Zarka 1998) and gravitational wave counterparts (Blanchet 2002;Abbott et al 2009). Radio observations serve an important role in the investigation of these objects and their variable behavior.…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Meter-Wavelength Radio Transient in the Swire Deep Field: 1046+59

Jaeger

Hyman

Kassim

et al. 2012

The Astronomical Journal

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We report the results of a low frequency radio variability and slow transient search using archival observations from the Very Long Array. We selected six 325 MHz radio observations from the spring of 2006, each centered on the Spitzer-Space-Telescope Wide-area Infrared Extragalactic Survey (SWIRE) Deep Field: 1046+59. Observations were spaced between one day to three months, with a typical single-epoch peak flux sensitivity below 0.2 mJy beam −1 near the field pointing center. We describe the observation parameters, data post-processing, and search methodology used to identify variable and transient emission. Our search revealed multiple variable sources and the presence of one, day-scale transient event with no apparent astronomical counterpart. This detection implies a transient rate of 1 ± 1 event per 6.5 deg 2 per 72 observing hours in the direction of 1046+59 and an isotropic transient surface density Σ = 0.12 deg −2 at 95% confidence for sources with average peak flux density higher than 2.1 mJy over 12 hr.

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“…Signatures of non-thermal electrons are also observed in radio waves (e.g. review by Bastian, Benz, and Gary, 1998) and HXR (e.g. review by Lin, 2011).…”

Section: Introductionmentioning

confidence: 99%

Observations of a Radio-Quiet Solar Preflare

Benz¹,

Battaglia²,

Güdel³

2017

Sol Phys

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The preflare phase of the flare SOL2011-08-09T03:52 is unique in its long duration, its coverage by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Nobeyama Radioheliograph, and the presence of three well-developed soft X-ray (SXR) peaks. No hard X-rays (HXR) are observed in the preflare phase. Here we report that also no associated radio emission at 17 GHz was found despite the higher sensitivity of the radio instrument. The ratio between the SXR peaks and the upper limit of the radio peaks is larger by more than one order of magnitude compared to regular flares. The result suggests that the ratio between acceleration and heating in the preflare phase was different than in regular flares. Acceleration to relativistic energies, if any, occurred with lower efficiency.

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Radio Emission From Solar Flares

Cited by 588 publications

References 215 publications

Discovery of radio emission from the brown dwarf LP944-20

Discovery of radio emission from the brown dwarf LP944-20

Discovery of a Meter-Wavelength Radio Transient in the Swire Deep Field: 1046+59

Observations of a Radio-Quiet Solar Preflare

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