Study of Coronal Jets During Solar Minimum Based on STEREO/SECCHI Observations

Paraschiv, Alin Rǎzvan; Lacatus, D. A.; Badescu, T.; Lupu, Maria Gabriela; Simon, Sabina; Sandu, S. G.; Mierla, M.; Rusu, Mircea

doi:10.1007/s11207-010-9584-6

Cited by 36 publications

(39 citation statements)

References 37 publications

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“…We found that numerous jets from coronal bright points in coronal holes and at their boundaries do carry high-density plasma at very high speeds throughout the solar atmosphere. It is now known that many of these jets reach the interplanetary space (Paraschiv et al 2010 The concentration of jet-like events in coronal holes and at their boundaries as shown in Paper II and their plasma characteristics obtained here make them an important candidate for one of the sources of the slow solar wind. Most recently, though, Neugebauer (2012) "proposed that the interplanetary manifestations of X-ray jets observed in solar polar coronal holes during periods of low solar activity are the peaks of the so-called microstreams observed in the fast polar solar wind".…”

Section: Discussionmentioning

confidence: 56%

“…The electron density of the jets was found to be 0.7−4 × 10 9 cm −3 while for the flaring site 2.4−10.0 × 10 9 cm −3 . These events are also observed in the ultraviolet (Alexander & Fletcher 1999;Ko et al 2005;Madjarska 2011) and white-light (Paraschiv et al 2010). Paraschiv et al (2010) analysed over 10 000 events observed in white-light by STEREO/SECCHI-COR1, and found that little more than 70% of the white-light jets were associated with EUV jets.…”

Section: Introductionmentioning

confidence: 99%

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Coronal hole boundaries evolution at small scales

Madjarska¹,

Huang²,

Doyle³

et al. 2012

A&A

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Context. We report on the plasma properties of small-scale transient events identified in the quiet Sun, coronal holes and their boundaries. Aims. We aim at deriving the physical characteristics of events that were identified as small-scale transient brightenings in XRT images. Methods. We used spectroscopic co-observations from SUMER/SoHO and EIS/Hinode combined with high-cadence imaging data from XRT/Hinode. We measured Doppler shifts using single and multiple Gaussian fits of the transition region and coronal lines as well as electron densities and temperatures. We combined co-temporal imaging and spectroscopy to separate brightening expansions from plasma flows. Results. The transient brightening events in coronal holes and their boundaries were found to be very dynamical, producing highdensity outflows at high speeds. Most of these events represent X-ray jets from pre-existing or newly emerging coronal bright points at X-ray temperatures. The average electron density of the jets is log 10 N e ≈ 8.76 cm −3 while in the flaring site it is log 10 N e ≈ 9.51 cm −3 . The jet temperatures reach a maximum of 2.5 MK but in the majority of the cases the temperatures do not exceed 1.6 MK. The footpoints of jets have maximum temperatures of 2.5 MK, though in a single event scanned a minute after the flaring the measured temperature was 12 MK. The jets are produced by multiple microflaring in the transition region and corona. Chromospheric emission was only detected in their footpoints and was only associated with downflows. The Doppler shift measurements in the quiet Sun transient brightenings confirmed that these events do not produce jet-like phenomena. The plasma flows in these phenomena remain trapped in closed loops. Conclusions. We can conclude that the dynamic day-by-day and even hour-by-hour small-scale evolution of coronal hole boundaries reported in Paper I is indeed related to coronal bright points. The XRT observations reported in Paper II revealed that these changes are associated with the dynamic evolution of coronal bright points producing multiple jets during their lifetime until their full disappearance. We demonstrate here through spectroscopic EIS and SUMER co-observations combined with high-cadence imaging information that the co-existence of open and closed magnetic fields results in multiple energy depositions, which propel high-density plasma along open magnetic field lines. We conclude from the physical characteristics obtained in this study that X-ray jets are important candidates for the source of the slow solar wind. This, however, does not exclude the possibility that these jets are also the microstreams observed in the fast solar wind, as recently suggested.

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Section: Discussionmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Coronal hole boundaries evolution at small scales

Madjarska¹,

Huang²,

Doyle³

et al. 2012

A&A

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“…of the bright points as observed in Extreme Ultraviolet Imager (EUVI; Wuelser et al 2004) 195 Å images at the time when the jet was observed in COR1. In Paraschiv et al (2010), we suggested that the number of jets with high outflow speeds is large enough to contribute significantly to the solar wind, and we concluded that these results may point to the mechanism responsible for the expansion of the jet, namely a pressure-driven expansion of the plasma. We later expanded the study (Paraschiv et al 2012) in order to discuss the possible contribution of coronal jets to the solar wind flux, by estimating the ejected particle mass flux of a selected subsample of the abovementioned coronal jets.…”

Section: Introductionmentioning

confidence: 82%

“…In our previous work (Paraschiv et al 2010), we identified and studied white-light jets observed by the SECCHI-COR1 white light coronagraph. We identified more than 10 000 whitelight jets spread across the entire solar limb at the minimum of solar activity between 2007 and 2008.…”

Section: Introductionmentioning

confidence: 99%

Physical properties of solar polar jets

Paraschiv

Бемпорад

Sterling

2015

A&A

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Aims. The target of this work is to investigate the physical nature of polar jets in the solar corona and their possible contribution to coronal heating and solar wind flow based on the analysis of X-ray images acquired by the Hinode XRT telescope. We estimate the different forms of energy associated with many of these small-scale eruptions, in particular the kinetic energy and enthalpy. Methods. Two Hinode XRT campaign datasets focusing on the two polar coronal holes were selected to analyze the physical properties of coronal jets; the analyzed data were acquired using a series of three XRT filters. Typical kinematical properties (e.g., length, thickness, lifetime, ejection rate, and velocity) of 18 jets are evaluated from the observed sequences, thus providing information on their possible contribution to the fast solar wind flux escaping from coronal holes. Electron temperatures and densities of polar-jet plasmas are also estimated using ratios of the intensities observed in different filters. Results. We find that the largest amount of energy eventually provided to the corona is thermal. The energy due to waves may also be significant, but its value is comparatively uncertain. The kinetic energy is lower than thermal energy, while other forms of energy are comparatively low. Lesser and fainter events seem to be hotter, thus the total contribution by polar jets to the coronal heating could have been underestimated so far. The kinetic energy flux is usually around three times smaller than the enthalpy counterpart, implying that this energy is converted into plasma heating more than in plasma acceleration. This result suggests that the majority of polar jets are most likely not escaping from the Sun and that only cooler ejections could possibly have enough kinetic energy to contribute to the total solar wind flow.

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“…A narrow CME was detected at 04:37 UT in Large Angle Spectroscopic Coronagraph (LASCO) on board SOHO. The CME may be the coronographic counterpart of the jet (Feng et al, 2012;Paraschiv et al, 2010;Nisticò et al, 2009). The observation was made using the extreme ultraviolet (EUV) passbands of the Atmospheric Imaging Assembly (AIA) onboard SDO.…”

Section: Observations and Data Analysismentioning

confidence: 99%

Transverse Oscillations in a Coronal Loop Triggered by a Jet

et al. 2016

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We detect and analyse transverse oscillations in a coronal loop, lying at the south east limb of the Sun as seen from the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). The jet is believed to trigger transverse oscillations in the coronal loop. The jet originates from a region close to the coronal loop on 19th September 2014 at 02:01:35 UT. The length of the loop is estimated to be between 377-539 Mm. Only one complete oscillation is detected with an average period of about 32 ± 5 min. Using MHD seismologic inversion techniques, we estimate the magnetic field inside the coronal loop to be between 2.68 − 4.5 G. The velocity of the hot and cool components of the jet is estimated to be 168 km s −1 and 43 km s −1 , respectively. The energy density of the jet is found to be greater than the energy density of the oscillating coronal loop. Therefore, we conclude that the jet triggered transverse oscillations in the coronal loop. To our knowledge, this is the first coronal loop seismology study using the properties of a jet propagation to trigger oscillations.

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Study of Coronal Jets During Solar Minimum Based on STEREO/SECCHI Observations

Cited by 36 publications

References 37 publications

Coronal hole boundaries evolution at small scales

Coronal hole boundaries evolution at small scales

Physical properties of solar polar jets

Transverse Oscillations in a Coronal Loop Triggered by a Jet

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