Jets in Polar Coronal Holes

Scullion, Eamon; Popescu, M. D.; Banerjee, D.; Doyle, J. G.; Erdélyi, R.

doi:10.1088/0004-637x/704/2/1385

Cited by 25 publications

(22 citation statements)

References 44 publications

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“…The east and west spicules apparently reside on the legs of the exploding blowout loop (arcade in three dimensions), and some of the substructure could result from the multiple locations of magnetic reconnection expected to be present, as indicated by the multiple reconnection × points in Figure 2(c). Scullion et al (2009) have also mapped strong jetlike events to cool features that may be spicules, and those could be similar to the hot material-cool material connections we find here. Sterling et al (2010) observed several cases where spicules appeared to start rising as a single structure, and then split into two or more structures.…”

Section: Summary and Discussionsupporting

confidence: 77%

Fibrillar Chromospheric Spicule-Like Counterparts to an Extreme-Ultraviolet and Soft X-Ray Blowout Coronal Jet

Sterling

Harra

Moore

2010

ApJ

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We observe an erupting jet feature in a solar polar coronal hole, using data from Hinode/Solar Optical Telescope (SOT), Extreme Ultraviolet Imaging Spectrometer (EIS), and X-Ray Telescope (XRT), with supplemental data from STEREO/EUVI. From extreme-ultraviolet (EUV) and soft X-ray (SXR) images we identify the erupting feature as a blowout coronal jet: in SXRs it is a jet with a bright base, and in EUV it appears as an eruption of relatively cool (∼50,000 K) material of horizontal size scale ∼30 originating from the base of the SXR jet. In SOT Ca ii H images, the most pronounced analog is a pair of thin (∼1 ) ejections at the locations of either of the two legs of the erupting EUV jet. These Ca ii features eventually rise beyond 45 , leaving the SOT field of view, and have an appearance similar to standard spicules except that they are much taller. They have velocities similar to that of "type II" spicules, ∼100 km s −1 , and they appear to have spicule-like substructures splitting off from them with horizontal velocity ∼50 km s −1 , similar to the velocities of splitting spicules measured by Sterling et al. Motions of splitting features and of other substructures suggest that the macroscopic EUV jet is spinning or unwinding as it is ejected. This and earlier work suggest that a subpopulation of Ca ii type II spicules are the Ca ii manifestation of portions of larger scale erupting magnetic jets. A different subpopulation of type II spicules could be blowout jets occurring on a much smaller horizontal size scale than the event we observe here.

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Section: Summary and Discussionsupporting

confidence: 77%

Fibrillar Chromospheric Spicule-Like Counterparts to an Extreme-Ultraviolet and Soft X-Ray Blowout Coronal Jet

Sterling

Harra

Moore

2010

ApJ

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“…Because the STEREO data are not taken exactly simultaneously, is not clear whether cool and hot jets co-occur within the same pixel. However, the analysis of McIntosh & De Pontieu (2009a) of co-located upflows for a wide range of temperatures, as well as observations of largescale jets in coronal holes that appear in simultaneous observations at 140 000 and 630 000 K (Scullion et al 2009) suggest that these events may well be truly multi-thermal. Observations with SDO/AIA will shed light on this issue, one that has important implications for the driving mechanism of these jets, although we expect that they are triggered by the complex interactions of the small scale magnetic flux elements at the base of the plume and its immediate surroundings (Gabriel et al 2009;Heggland et al 2009).…”

Section: Discussionmentioning

confidence: 99%

STEREO observations of quasi-periodically driven high velocity outflows in polar plumes

McIntosh¹,

Innes

Pontieu

et al. 2010

A&A

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Context. Plumes are one of the most ubiquitous features seen at the limb in polar coronal holes and are considered to be a source of high density plasma streams to the fast solar wind. Aims. We analyze STEREO observations of plumes and aim to reinterpret and place observations with previous generations of EUV imagers within a new context that was recently developed from Hinode observations. Methods. We exploit the higher signal-to-noise, spatial and temporal resolution of the EUVI telescopes over that of SOHO/EIT to study the temporal variation of polar plumes in high detail. We employ recently developed insight from imaging (and spectral) diagnostics of active region, plage, and quiet Sun plasmas to identify the presence of apparent motions as high-speed upflows in magnetic regions as opposed to previous interpretations of propagating waves.Results. In almost all polar plumes observed at the limb in these STEREO sequences, in all coronal passbands, we observe high speed jets of plasma traveling along the structures with a mean velocity of 135 km s −1 at a range of temperatures from 0.5-1.5 MK. The jets have an apparent brightness enhancement of ∼5% above that of the plumes they travel on and repeat quasi-periodically, with repeattimes ranging from five to twenty-five minutes. We also notice a very weak, fine scale, rapidly evolving, but ubiquitous companion of the plumes that covers the entire coronal hole limb. Conclusions. The observed jets are remarkably similar in intensity enhancement, periodicity and velocity to those observed in other magnetic regions of the solar atmosphere. They are multi-thermal in nature. We infer that the jets observed on the plumes are a source of heated mass to the fast solar wind. Further, based on the previous results that motivated this study, we suggest that these jets originated in the upper chromosphere.

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“…Figure 1 shows the location of the SUMER slit in an image of the south polar coronal hole taken in the 195 Å passband with the Extreme ultraviolet Imaging Telescope (EIT, Delaboudinière et al 1995) onboard SOHO. Scullion et al (2009) also analyzed the same dataset to identify and characterize jet events.…”

Section: Data Reduction and Analysismentioning

confidence: 99%

Spectroscopic observations of propagating disturbances in a polar coronal hole: evidence of slow magneto-acoustic waves

Gupta

Teriaca

Marsch

et al. 2012

A&A

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Aims. We focus on detecting and studying quasi-periodic propagating features that have been interpreted in terms of both slow magneto-acoustic waves and of high-speed upflows. Methods. We analyzed long-duration spectroscopic observations of the on-disk part of the south polar coronal hole taken on 1997 February 25 by the SUMER spectrometer onboard SOHO. We calibrated the velocity with respect to the off-limb region and obtained time-distance maps in intensity, Doppler velocity, and line width. We also performed a cross-correlation analysis on different time series curves at different latitudes. We studied average spectral line profiles at the roots of propagating disturbances and along the propagating ridges, and performed a red-blue asymmetry analysis. Results. We clearly find propagating disturbances in intensity and Doppler velocity with a projected propagation speed of about 60 ± 4.8 km s −1 and a periodicity of ≈14.5 min. To our knowledge, this is the first simultaneous detection of propagating disturbances in intensity as well as in Doppler velocity in a coronal hole. During the propagation, an intensity enhancement is associated with a blueshifted Doppler velocity. These disturbances are clearly seen in intensity also at higher latitudes (i.e., closer to the limb), while disturbances in Doppler velocity become faint there. The spectral line profiles averaged along the propagating ridges are found to be symmetric, to be well fitted by a single Gaussian, and have no noticeable red-blue asymmetry. Conclusions. Based on our analysis, we interpret these disturbances in terms of propagating slow magneto-acoustic waves.

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Jets in Polar Coronal Holes

Cited by 25 publications

References 44 publications

Fibrillar Chromospheric Spicule-Like Counterparts to an Extreme-Ultraviolet and Soft X-Ray Blowout Coronal Jet

Fibrillar Chromospheric Spicule-Like Counterparts to an Extreme-Ultraviolet and Soft X-Ray Blowout Coronal Jet

STEREO observations of quasi-periodically driven high velocity outflows in polar plumes

Spectroscopic observations of propagating disturbances in a polar coronal hole: evidence of slow magneto-acoustic waves

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