The High-Resolution Coronal Imager (Hi-C)

Kobayashi, K.; Cirtain, Jonathan; Winebarger, Amy R.; Korreck, K. E.; Golub, L.; Walsh, R. W.; Pontieu, Bart De; DeForest, C. E.; Title, A. M.; Kuzin, Sergey; Savage, Sabrina; Beabout, Dyana; Beabout, Brent; Podgorski, William; Caldwell, David; McCracken, K. G.; Ordway, Mark; Bergner, Henry; Gates, Richard; McKillop, S.; Cheimets, Peter; Platt, S. P.; Mitchell, Nick; Windt, David L.

doi:10.1007/s11207-014-0544-4

Cited by 139 publications

(105 citation statements)

References 27 publications

Supporting

Mentioning

100

Contrasting

Unclassified

Order By: Relevance

“…From this Wang (2016) concluded that there must be small-scale opposite magnetic polarities embedded within the plage region that appears to be unipolar to HMI with its limited spatial resolution of no better than 1 (corresponding to 725 km on the Sun at disk center). This is similar to the interpretation given earlier by Peter et al (2013) for even smaller loop-like features with lengths of only 1 Mm seen with the High-resolution Coronal Imager (Hi-C; Kobayashi et al 2014). While the spatial resolution of the coronal images of Hi-C is about 0.3 (and thus more than three times better than AIA), the conclusions of Peter et al (2013) had to rely on the comparably poor resolution of HMI, too.…”

Section: Introductionsupporting

confidence: 82%

Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields

Chitta

Peter

Solanki

et al. 2017

ApJS

View full text Add to dashboard Cite

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the solar corona. To address the above question, we use highresolution line-of-sight magnetic field data from the Imaging Magnetograph eXperiment instrument on the Sunrise balloon-borne observatory and coronal observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory of an emerging active region. We find that the coronal loops are often rooted at the locations with minor small-scale but persistent oppositepolarity magnetic elements very close to the larger dominant polarity. These opposite-polarity smallscale elements continually interact with the dominant polarity underlying the coronal loop through flux cancellation. At these locations we detect small inverse Y-shaped jets in chromospheric Ca ii H images obtained from the Sunrise Filter Imager during the flux cancellation. Our results indicate that magnetic flux cancellation and reconnection at the base of coronal loops due to mixed polarity fields might be a crucial feature for the supply of mass and energy into the corona.

show abstract

Section: Introductionsupporting

confidence: 82%

Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields

Chitta

Peter

Solanki

et al. 2017

ApJS

View full text Add to dashboard Cite

show abstract

“…We have found that, just as the coronal loops seen in EUV (Tousey et al 1977) essentially all contain unresolved image-plane structure down to the smallest observable scales (e.g., DeForest 2007; Kobayashi et al 2014), so too do outer-coronal structures, such as streamers, pseudostreamers, plumes, rays, and related density structures ("striae").…”

Section: The Spatially Structured Outer Coronamentioning

confidence: 76%

The Highly Structured Outer Solar Corona

DeForest

Howard

Velli

et al. 2018

ApJ

137

111

View full text Add to dashboard Cite

We report on the observation of fine-scale structure in the outer corona at solar maximum, using deep-exposure campaign data from the Solar Terrestrial Relations Observatory-A (STEREO-A)/COR2 coronagraph coupled with postprocessing to further reduce noise and thereby improve effective spatial resolution. The processed images reveal radial structure with high density contrast at all observable scales down to the optical limit of the instrument, giving the corona a "woodgrain" appearance. Inferred density varies by an order of magnitude on spatial scales of 50 Mm and follows an f −1 spatial spectrum. The variations belie the notion of a smooth outer corona. They are inconsistent with a well-defined "Alfvén surface," indicating instead a more nuanced "Alfvén zone"-a broad trans-Alfvénic region rather than a simple boundary. Intermittent compact structures are also present at all observable scales, forming a size spectrum with the familiar "Sheeley blobs" at the large-scale end. We use these structures to track overall flow and acceleration, finding that it is highly inhomogeneous and accelerates gradually out to the limit of the COR2 field of view. Lagged autocorrelation of the corona has an enigmatic dip around 10 R e , perhaps pointing to new phenomena near this altitude. These results point toward a highly complex outer corona with far more structure and local dynamics than has been apparent. We discuss the impact of these results on solar and solar-wind physics and what future studies and measurements are necessary to build upon them.

show abstract

“…The High Resolution Coronal Imager (Hi-C; Cirtain et al 2013;Kobayashi et al 2014) provided unprecedented high-quality coronal images and first detected two locations of braided coronal structures in an active region corona. Hi-C images, with a spatial resolution of about 150 km and a cadence of 5 s, were obtained using a narrow passband filter centered at 193 Å, which is emitted by Fe XII at about 1.5 MK (Cirtain et al 2013).…”

Section: Hi-c Observationsmentioning

confidence: 99%

Observable Signatures of Energy Release in Braided Coronal Loops

Pontin

Janvier

Tiwari

et al. 2017

ApJ

View full text Add to dashboard Cite

We examine the turbulent relaxation of solar coronal loops containing non-trivial field line braiding. Such field line tangling in the corona has long been postulated in the context of coronal heating models. We focus on the observational signatures of energy release in such braided magnetic structures using MHD simulations and forward modeling tools. The aim is to answer the following question: if energy release occurs in a coronal loop containing braided magnetic flux, should we expect a clearly observable signature in emissions? We demonstrate that the presence of braided magnetic field lines does not guarantee a braided appearance to the observed intensities. Observed intensities may-but need not necessarily-reveal the underlying braided nature of the magnetic field, depending on the degree and pattern of the field line tangling within the loop. However, in all cases considered, the evolution of the braided loop is accompanied by localized heating regions as the loop relaxes. Factors that may influence the observational signatures are discussed. Recent high-resolution observations from Hi-C have claimed the first direct evidence of braided magnetic fields in the corona. Here we show that both the Hi-C data and some of our simulations give the appearance of braiding at a range of scales.

show abstract

The High-Resolution Coronal Imager (Hi-C)

Cited by 139 publications

References 27 publications

Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields

Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields

The Highly Structured Outer Solar Corona

Observable Signatures of Energy Release in Braided Coronal Loops

Contact Info

Product

Resources

About