Transient Mass-loss Analysis of Solar Observations Using Stellar Methods

Crosley, Michael K.; Osten, Rachel A.; Norman, C.

doi:10.3847/1538-4357/aa7edc

Cited by 6 publications

(7 citation statements)

References 22 publications

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“…To estimate the density at 2R * , we assume that density decreases exponentially with height above the base of the corona, following the approach of Crosley et al (2017), who use Sun-as-a-star data to build a framework for interpretation of stellar Type II bursts. We use the density scale height for material in hydrostatic equilibrium (HSE) under constant gravity, H = k B T /(µm H g) ≈ (50 Mm)T 6 R 2 * /M * , where R * and M * are in solar units, and and µ = 0.6 is the mean molecular weight of the solar corona.…”

Section: Choice Of Frequency Bandsmentioning

confidence: 99%

“…Of note are solar Type II and III bursts, which are plasma emission originating from coronal shock fronts and electron beams, respectively. Measuring frequency drift rate, combined with a model of the spatial variation of plasma density or magnetic field strength with height h, enables estimation of an apparent source ve-locity (more detailed treatments can be found in, e.g., Crosley et al 2017). If a source is moving outwards radially at constant speed V = dh/dt, the frequency drift rate ν is:…”

Section: Source Motion Both Plasma Emission and Ecm Canmentioning

confidence: 99%

“…Both of these classes of bursts are correlated with solar space weather events that impact Earth: coronal mass ejections and solar energetic particle (SEP) events (Kouloumvakos et al 2015). Analogous events, tracing bulk motion of plasma, may be detectable from nearby stars; and based on Sun-as-a-star data, such stellar radio bursts can be used to recover approximate dynamical properties of CMEs (Crosley et al 2017). This suggests that low-frequency radio observations can be used to characterize stellar mass loss and the space weather environment experienced by extrasolar planets.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-wideband Detection of 22 Coherent Radio Bursts on M Dwarfs

Villadsen

Hallinan

2019

ApJ

103

106

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Coherent radio bursts detected from M dwarfs have some analogy with solar radio bursts, but reach orders of magnitude higher luminosities. These events trace particle acceleration, powered by magnetic reconnection, shock fronts (such as formed by coronal mass ejections, CMEs), and magnetospheric currents, in some cases offering the only window into these processes in stellar atmospheres. We conducted a 58-hour, ultra-wideband survey for coherent radio bursts on 5 active M dwarfs. We used the Karl G. Jansky Very Large Array (VLA) to observe simultaneously in three frequency bands covering a subset of 224-482 MHz and 1-6 GHz, achieving the widest fractional bandwidth to date for any observations of stellar radio bursts. We detected 22 bursts across 13 epochs, providing the first large sample of wideband dynamic spectra of stellar coherent radio bursts. The observed bursts have diverse morphology, with durations ranging from seconds to hours, but all share strong (40-100%) circular polarization. No events resemble solar Type II bursts (often associated with CMEs), but we cannot rule out the occurrence of radio-quiet stellar CMEs. The hours-long bursts are all polarized in the sense of the x-mode of the star's large-scale magnetic field, suggesting they are cyclotron maser emission from electrons accelerated in the large-scale field, analogous to auroral processes on ultracool dwarfs. The duty cycle of luminous coherent bursts peaks at 25% at 1-1.4 GHz, declining at lower and higher frequencies, indicating source regions in the low corona. At these frequencies, active M dwarfs should be the most common galactic transient source.

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Section: Choice Of Frequency Bandsmentioning

confidence: 99%

Section: Source Motion Both Plasma Emission and Ecm Canmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultra-wideband Detection of 22 Coherent Radio Bursts on M Dwarfs

Villadsen

Hallinan

2019

ApJ

103

106

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“…These are now a single variable equations of E rad (v) and v(E rad ). The errors of the above equations are discussed in detail in Crosley et al (2017). The results of equation ( 11) is suggested to be only useful to an approximate order of magnitude while equation ( 12) is suggested to be accurate to within a factor of 2.…”

Section: Flare Observationsmentioning

confidence: 99%

Constraining Stellar Coronal Mass Ejections through Multi-wavelength Analysis of the Active M Dwarf EQ Peg

Crosley

Osten

2018

ApJ

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Stellar coronal mass ejections remain experimentally unconstrained, unlike their stellar flare counterparts which are observed ubiquitously across the electromagnetic spectrum. Low frequency radio bursts in the form of a type II burst offer the best means of identifying and constraining the rate and properties of stellar CMEs. CME properties can be further improved through the use of proposed solar-stellar scaling relations and multi-wavelength observations of CMEs through the use of type II bursts and the associated flare expected to occur occur alongside. We report on 20 hours of observation of the nearby, magnetically active, and well characterized M dwarf star EQ Peg. The observations are simultaneously observed with the Jansky Very Large Array at their P-band (230-470 MHz) and at the Apache Point observatory in the SDSS u' filter (λ = 3557Å).Dynamic spectra of the P band data, constructed to search for signals in the frequency-time domains, did not reveal evidence for drifting radio bursts that could be ascribed to type II bursts. Given the sensitivity of our observations, we are able to place limits on the brightness temperature and source size of any bursts which may have occurred. Using solar scaling rations on four observed stellar flares, we predict CME parameters. Given the constraints on coronal density and photospheric field strength, our models suggest that the observed flares would have been insufficient to produce detectable type II bursts at our observed frequencies. We consider the implications of these results, and other recent findings, on stellar mass loss.

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“…Subsequent studies have also found that solar eruptive events tend to have similar amounts of energy in radiation and energetic particles (as measured through X-rays; Emslie et al 2012), while M dwarf flares tend to have a larger fraction of energy in nonthermal particles (Smith, Güdel, & Audard 2005). One positive step forward was recently made by Osten and her collaborators (Crosley, Osten, & Norman 2017), who in effect observed the Sun as an unresolved star in order to develop a framework for the interpretation of stellar events and the derivation of parameters such as CME velocities, masses, and kinetic energies.…”

Section: Extrasolar Space Weathermentioning

confidence: 99%

Radio Stars: From kHz to THz

Matthews¹

2018

PASP

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Advances in technology and instrumentation have now opened up virtually the entire radio spectrum to the study of stars. An international workshop Radio Stars: from kHz to THz was held at the Massachusetts Institute of Technology Haystack Observatory on 2017 November 1-3 to enable the discussion of progress in solar and stellar astrophysics enabled by radio wavelength observations. Topics covered included the Sun as a radio star, radio emission from hot and cool stars (from the pre-to post-main-sequence), ultracool dwarfs, stellar activity, stellar winds and mass loss, planetary nebulae, cataclysmic variables, classical novae, and the role of radio stars in understanding the Milky Way. This article summarizes meeting highlights along with some contextual background information.

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Transient Mass-loss Analysis of Solar Observations Using Stellar Methods

Cited by 6 publications

References 22 publications

Ultra-wideband Detection of 22 Coherent Radio Bursts on M Dwarfs

Ultra-wideband Detection of 22 Coherent Radio Bursts on M Dwarfs

Constraining Stellar Coronal Mass Ejections through Multi-wavelength Analysis of the Active M Dwarf EQ Peg

Radio Stars: From kHz to THz

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