Observations and Numerical Models of Solar Coronal Heating Associated with Spicules

Pontieu, Bart De; Moortel, I. De; Martínez-Sykora, Juan; McIntosh, Scott W.

doi:10.3847/2041-8213/aa7fb4

Cited by 48 publications

(38 citation statements)

References 51 publications

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“…Nanoflares were observed as EUV brightenings in the corona (Benz & Krucker 1998;Ishikawa et al 2017). Spicules were dynamic jet-like features in the chromosphere or corona (Pereira et al 2016;De Pontieu et al 2017). Solar tornadoes were observed as tornado-like structures of magnetized plasmas in the corona (Su et al 2012;Wedemeyer-Böhm et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic and imaging observations of small-scale reconnection events

Dong

Ning

2018

Monthly Notices of the Royal Astronomical Society

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We present spectroscopic and imaging observations of small-scale reconnection events on the Sun. Using the Interface Region Imaging Spectrograph (IRIS) observations, one reconnection event is first detected as IRIS jets with fast bi-directional velocities in the chromosphere and transition region, which are identified as non-Gaussian broadenings with two extended wings in the line profiles of Si iv, C ii, and Mg ii k. The magnetograms under the IRIS jets from Helioseismic and Magnetic Images exhibit magnetic flux cancellation simultaneously, supporting that the IRIS jets are driven by magnetic reconnection. The Atmospheric Imaging Assembly images also show an extreme ultraviolet (EUV) brightening which is shortly after the underlying IRIS jets, i.e., in the 131Å, 171Å, 193Å, 211Å, and 94Å channels, implying that the overlying EUV brightening in the corona is caused by the IRIS jets in the chromosphere and transition region. We also find another three reconnection events which show the same features during this IRIS observation. Our observational results suggest that the small-scale reconnection events might contribute to the coronal heating. The new result is that the process of magnetic reconnection is detected from the photosphere through chromosphere and transition region to the corona.

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Section: Discussionmentioning

confidence: 99%

Spectroscopic and imaging observations of small-scale reconnection events

Dong

Ning

2018

Monthly Notices of the Royal Astronomical Society

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“…From the number density of emitters and emissivity results of Section 4 we gather that calculating heavy element populations directly through the rate equations instead of via the assumption of statistical equilibrium can be important to understand the observations of surges (and of other fast phenomena which reach TR temperatures in their periphery like spicules De Pontieu et al 2017, or UV bursts Hansteen et al 2017. In that section, analyzing the Si IV and O IV emissivities of the plasma elements, we find that the ratio between them is approximately 2 in the regions with the highest emission within the ETR.…”

Section: Understanding Observations and Predictions For The Futurementioning

confidence: 99%

On the Importance of the Nonequilibrium Ionization of Si iv and O iv and the Line of Sight in Solar Surges

Nóbrega-Siverio¹,

Moreno‐Insertis²,

Martínez-Sykora³

2018

ApJ

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Surges are ubiquitous cool ejections in the solar atmosphere that often appear associated with transient phenomena like UV bursts or coronal jets. Recent observations from the Interface Region Imaging Spectrograph (IRIS) show that surges, although traditionally related to chromospheric lines, can exhibit enhanced emission in Si IV with brighter spectral profiles than for the average transition region (TR). In this paper, we explain why surges are natural sites to show enhanced emissivity in TR lines. We performed 2.5D radiative-MHD numerical experiments using the Bifrost code including the nonequilibrium ionization of silicon and oxygen. A surge is obtained as a by-product of magnetic flux emergence; the TR enveloping the emerged domain is strongly affected by nonequilibrium effects: assuming statistical equilibrium would produce an absence of Si IV and O IV ions in most of the region. Studying the properties of the surge plasma emitting in the Si IV 1402.77Å and O IV 1401.16Å lines, we find that a) the timescales for the optically-thin losses and heat conduction are very short, leading to departures from statistical equilibrium, and b) the surge emits in Si IV more and has an emissivity ratio of Si IV to O IV larger than a standard TR. Using synthetic spectra, we conclude the importance of line-of-sight effects: given the involved geometry of the surge, the line-of-sight can cut the emitting layer at small angles and/or cross it multiple times, causing prominent, spatially intermittent brightenings both in Si IV and O IV.

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“…While they may play an important role in mass and energy injected into the corona, their coronal counterparts are difficult to study because they are faint, small (diameters < 0.5 arcsec), and short-lived (10 -20 s) (De Pontieu et al, 2011). Features that may be the coronal counterparts to type-II spicules were seen in Hi-C 1 data (Régnier et al, 2014) and IRIS and SDO/AIA data (De Pontieu et al, 2017), but cospatial and co-temporal high-resolution observations of the chromosphere, transition region and corona are needed to determine the correlation.…”

Section: Introductionmentioning

confidence: 99%

The High-Resolution Coronal Imager, Flight 2.1

et al. 2019

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The third flight of the High-Resolution Coronal Imager (Hi-C 2.1) occurred on May 29, 2018; the Sounding Rocket was launched from White Sands Missile Range in New Mexico. The instrument has been modified from its original configuration (Hi-C 1) to observe the solar corona in a passband that peaks near 172 Å, and uses a new, custom-built low-noise camera. The instrument targeted Active Region 12712, and captured 78 images at a cadence of 4.4 s (18:56:22-19:01:57 UT; 5 min and 35 s observing time). The image spatial resolution varies due to quasi-periodic motion blur from the rocket; sharp images contain resolved features of at least 0.47 arcsec. There are coordinated observations from multiple ground-and space-based telescopes providing an unprecedented opportunity to observe the mass and energy coupling between the chromosphere and the corona. Details of the instrument and the data set are presented in this paper.

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Observations and Numerical Models of Solar Coronal Heating Associated with Spicules

Cited by 48 publications

References 51 publications

Spectroscopic and imaging observations of small-scale reconnection events

Spectroscopic and imaging observations of small-scale reconnection events

On the Importance of the Nonequilibrium Ionization of Si iv and O iv and the Line of Sight in Solar Surges

The High-Resolution Coronal Imager, Flight 2.1

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