Statistical Study of Network Jets Observed in the Solar Transition Region: a Comparison Between Coronal Holes and Quiet-Sun Regions

Narang, Nancy; Arbacher, Rebecca Tate; Tian, Hui; Banerjee, D.; Cranmer, Steven R.; DeLuca, E. E.; McKillop, S.

doi:10.1007/s11207-016-0886-1

Cited by 37 publications

(57 citation statements)

References 52 publications

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“…The second apparent jet follows a similar scenario and occurs at t=670 s in the left spicule at somewhat greater heights. These timescales, speeds, and synthetic observables all are in agreement with the observations (Tian et al 2014;Narang et al 2016). We note that this is not the only possible cause for fast apparent jets at transition region temperatures.…”

Section: Measurementssupporting

confidence: 89%

“…To compare our simulation with observations, we calculate the synthetic Si IV intensity assuming equilibrium ionization and the optically thin approximation, similar to the methods used by Hansteen et al (2010). ) spicules (Narang et al 2016). Such fast motions in spicules also occur in active regions.…”

Section: Simulationsmentioning

confidence: 99%

“…In contrast to type I spicules, type II spicules often appear to be associated with heating to at least transition region temperatures (De Pontieu et al 2014a;Rouppe van der Voort et al 2015). Their short-lived (~-20 50 s) transition region counterparts often appear in Si IV and C II slit-jaw images (SJI) from the Interface Region Imaging Spectrograph (IRIS; De Pontieu et al 2014b) as linear features that emanate from magnetic network with even higher apparent speeds of 80-300 km s −1 (Tian et al 2014;Narang et al 2016). The transition region counterparts appear to be shorter and slower in quiet Sun than in coronal holes, presumably because of differing magnetic field configurations (Narang et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Their short-lived (~-20 50 s) transition region counterparts often appear in Si IV and C II slit-jaw images (SJI) from the Interface Region Imaging Spectrograph (IRIS; De Pontieu et al 2014b) as linear features that emanate from magnetic network with even higher apparent speeds of 80-300 km s −1 (Tian et al 2014;Narang et al 2016). The transition region counterparts appear to be shorter and slower in quiet Sun than in coronal holes, presumably because of differing magnetic field configurations (Narang et al 2016). Such high apparent speeds have also been found in other upperchromospheric lines such as Lyα (Kubo et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?

Pontieu

Martínez-Sykora

Chintzoglou

2017

ApJL

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Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed the presence of very high apparent motions of order 100-300 km s −1 in spicules, as measured in the plane of the sky. However, line of sight measurements of such high speeds have been difficult to obtain, with values deduced from Doppler shifts in spectral lines typically of order 30-70 km s −1 . In this work, we resolve this long-standing discrepancy using recent 2.5D radiative MHD simulations. This simulation has revealed a novel driving mechanism for spicules in which ambipolar diffusion resulting from ion-neutral interactions plays a key role. In our simulation, we often see that the upward propagation of magnetic waves and electrical currents from the low chromosphere into already existing spicules can lead to rapid heating when the currents are rapidly dissipated by ambipolar diffusion. The combination of rapid heating and the propagation of these currents at Alfvénic speeds in excess of 100 km s −1 leads to the very rapid apparent motions, and often wholesale appearance, of spicules at chromospheric and transition region temperatures. In our simulation, the observed fast apparent motions in such jets are actually a signature of a heating front, and much higher than the mass flows, which are of order 30-70 km s −1 . Our results can explain the behavior of transition region "network jets" and the very high apparent speeds reported for some chromospheric spicules.

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Section: Measurementssupporting

confidence: 89%

Section: Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?

Pontieu

Martínez-Sykora

Chintzoglou

2017

ApJL

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“…For coronal holes, the driver of this plasma emission might be the transition region network jets discovered by the Interface Region Imaging Spectrograph (Tian et al, 2014). These jets are continuously generated throughout the transition region, but they are particularly common and intense inside coronal holes (Narang et al, 2016). They strongly resemble the coronal X-ray jets associated with Type III bursts, and some attribute the network jets to small-scale reconnection events (Tian et al, 2014;Kayshap et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

The Low-Frequency Solar Corona in Circular Polarization

et al. 2019

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We present spectropolarimetric imaging observations of the solar corona at low frequencies (80 -240 MHz) using the Murchison Widefield Array (MWA). These images are the first of their kind, and we introduce an algorithm to mitigate an instrumental artefact by which the total intensity signal contaminates the polarimetric images due to calibration errors. We then survey the range of circular polarization (Stokes V ) features detected in over 100 observing runs near solar maximum during quiescent periods. First, we detect around 700 compact polarized sources across our dataset with polarization fractions ranging from less than 0.5 % to nearly 100 %. These sources exhibit a positive correlation between polarization fraction and total intensity, and we interpret them as a continuum of plasma emission noise storm (Type I burst) continua sources associated with active regions. Second, we report a characteristic "bullseye" structure observed for many low-latitude coronal holes in which a central polarized component is surrounded by a ring of the opposite sense. The central component does not match the sign expected from thermal bremsstrahlung emission, and we speculate that propagation effects or an alternative emission mechanism may be responsible. Third, we show that the large-scale polarimetric structure at our lowest frequencies is reasonably well-correlated with the line-of-sight (LOS) magnetic field component inferred from a global potential field source surface (PFSS) model. The boundaries between opposite circular polarization signs are generally aligned with polarity inversion lines in the model at a height roughly corresponding to that of the radio limb. This is not true at our highest frequencies, however, where the LOS magnetic field direction and polarization sign are often not straightforwardly correlated.

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On the Relation Between Transition Region Network Jets and Coronal Plumes

Huang

Xia

et al. 2019

Sol Phys

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Statistical Study of Network Jets Observed in the Solar Transition Region: a Comparison Between Coronal Holes and Quiet-Sun Regions

Cited by 37 publications

References 52 publications

What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?

What Causes the High Apparent Speeds in Chromospheric and Transition Region Spicules on the Sun?

The Low-Frequency Solar Corona in Circular Polarization

On the Relation Between Transition Region Network Jets and Coronal Plumes

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