Observation and Modeling of Chromospheric Evaporation in a Coronal Loop Related to Active Region Transient Brightening

Gupta, G. R.; Sarkar, Aveek; Tripathi, Durgesh

doi:10.3847/1538-4357/aab95e

Cited by 25 publications

(21 citation statements)

References 58 publications

(59 reference statements)

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“…6), which is best seen at the high cadence of the ALMA observations. Interestingly, we do not observe any cospatial 1600 Å emission in the hot loops in either of the events, unlike, for example, in the FAFs reported in Vissers et al (2015) or the transient brightenings in Pariat et al (2009) and Gupta et al (2018), which suggests that the bulk of the plasma is not at temperatures between log T ∼ 4.2−5.1 K to which AIA 1600 Å would be sensitive (Simões et al 2019).…”

Section: Flaring Fibrilscontrasting

confidence: 61%

ALMA observations of transient heating in a solar active region

Santos

Rodríguez

White

et al. 2020

A&A

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Aims. We aim to investigate the temperature enhancements and formation heights of solar active-region brightenings such as Ellerman bombs (EBs), ultraviolet bursts (UVBs), and flaring active-region fibrils (FAFs) using interferometric observations in the millimeter (mm) continuum provided by the Atacama Large Millimeter/submillimeter Array (ALMA). Methods. We examined 3 mm signatures of heating events identified in Solar Dynamics Observatory observations of an active region and compared the results with synthetic spectra from a 3D radiative magnetohydrodynamic simulation. We estimated the contribution from the corona to the mm brightness using differential emission measure analysis. Results. We report the null detection of EBs in the 3 mm continuum at ∼1.2″ spatial resolution, which is evidence that they are sub-canopy events that do not significantly contribute to heating the upper chromosphere. In contrast, we find the active region to be populated with multiple compact, bright, flickering mm-bursts – reminiscent of UVBs. The high brightness temperatures of up to ∼14 200 K in some events have a contribution (up to ∼7%) from the corona. We also detect FAF-like events in the 3 mm continuum. These events show rapid motions of > 10 kK plasma launched with high plane-of-sky velocities (37 − 340 km s−1) from bright kernels. The mm FAFs are the brightest class of warm canopy fibrils that connect magnetic regions of opposite polarities. The simulation confirms that ALMA should be able to detect the mm counterparts of UVBs and small flares and thus provide a complementary diagnostic for localized heating in the solar chromosphere.

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Section: Flaring Fibrilscontrasting

confidence: 61%

ALMA observations of transient heating in a solar active region

Santos

Rodríguez

White

et al. 2020

A&A

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“…Further observational analysis is required to build statistics on the presence (or lack) of these near-simultaneous footpoint brightenings in association with brightenings of hot coronal loops (e.g. Gupta et al 2018). In addition, it would be interesting to conduct numerical experiments to investigate the role of footpoint reconnection and the local energy deposition in the generation of a nearsimultaneous signal at both footpoints.…”

Section: Discussionmentioning

confidence: 99%

Nature of the energy source powering solar coronal loops driven by nanoflares

Chitta

Peter

Solanki

2018

A&A

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Context. Magnetic energy is required to heat the corona, the outer atmosphere of the Sun, to millions of degrees. Aims. We study the nature of the magnetic energy source that is probably responsible for the brightening of coronal loops driven by nanoflares in the cores of solar active regions. Methods. We consider observations of two active regions (ARs), 11890 and 12234, in which nanoflares have been detected. To this end, we use ultraviolet (UV) and extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) for coronal loop diagnostics. These images are combined with the co-temporal line-of-sight magnetic field maps from the Helioseismic and Magnetic Imager (HMI) onboard SDO to investigate the connection between coronal loops and their magnetic roots in the photosphere.Results. The core of these ARs exhibit loop brightening in multiple EUV channels of AIA, particularly in its 9.4 nm filter. The HMI magnetic field maps reveal the presence of a complex mixed polarity magnetic field distribution at the base of these loops. We detect the cancellation of photospheric magnetic flux at these locations at a rate of about 10 15 Mx s −1 . The associated compact coronal brightenings directly above the cancelling magnetic features are indicative of plasma heating due to chromospheric magnetic reconnection.Conclusions. We suggest that the complex magnetic topology and the evolution of magnetic field, such as flux cancellation in the photosphere and the resulting chromospheric reconnection, can play an important role in energizing active region coronal loops driven by nanoflares. Our estimate of magnetic energy release during flux cancellation in the quiet Sun suggests that chromospheric reconnection can also power the quiet corona.

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“…It is not clear if this peak arises from the event as the GOES flux is an average over the entire solar disk, but if it is then the energy of an A-class flare is implied. This event has been studied in more detail in a recent paper of Gupta et al (2018).…”

Section: Mini Flare Ribbonsmentioning

confidence: 97%

Solar Ultraviolet Bursts

et al. 2018

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The term "ultraviolet (UV) burst" is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling oppositepolarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the lat-Electronic supplementary material The online version of this article (https://doi.

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Observation and Modeling of Chromospheric Evaporation in a Coronal Loop Related to Active Region Transient Brightening

Cited by 25 publications

References 58 publications

ALMA observations of transient heating in a solar active region

ALMA observations of transient heating in a solar active region

Nature of the energy source powering solar coronal loops driven by nanoflares

Solar Ultraviolet Bursts

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