Intensity oscillations and heating of the coronal X-ray bright points from Hinode/XRT

Kariyappa, R.; Varghese, B. A.

doi:10.1051/0004-6361:20079127

Cited by 23 publications

(22 citation statements)

References 19 publications

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“…2 and 3) observed with the two filters and the fluctuations have similar patterns in both cases. The temporal variations in the intensity of XBPs observed with Ti_poly filter show an intensity oscillations on timescales of between a few minutes and hours (Kariyappa & Varghese 2008). From Figs.…”

Section: Resultsmentioning

confidence: 74%

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Temperature variability in X-ray bright points observed with Hinode/XRT

Kariyappa

DeLuca

Saar

et al. 2010

A&A

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Aims. We investigate the variability in temperature as a function of time among a sample of coronal X-ray bright points (XBPs). Methods. We analysed a 7-h (17:00-24:00 UT) long time sequence of soft X-ray images observed almost simultaneously in two filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope (XRT) onboard the Hinode mission. We identified and selected 14 XBPs for a detailed analysis. The light curves of XBPs were derived using the SolarSoft library in IDL. The temperature of XBPs was determined using the calibrated temperature response curves of the two filters by means of the intensity ratio method. Results. We find that the XBPs show a high variability in their temperature and that the average temperature ranges from 1.1 MK to 3.4 MK. The variations in temperature are often correlated with changes in average X-ray emission. It is evident from the results of time series that the XBP heating rate can be highly variable on short timescales, suggesting that it has a reconnection origin.

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Section: Resultsmentioning

confidence: 74%

“…XBPs observed using Hinode/XRT and Yohkoh/SXT have been found to exhibit intensity oscillations on timescales of between a few minutes and hours (Kariyappa & Varghese 2008;Strong et al 1992). Similar variations in the brightness of coronal bright points observed with EIT data were reported by .…”

Section: Introductionmentioning

confidence: 99%

Temperature variability in X-ray bright points observed with Hinode/XRT

Kariyappa

DeLuca

Saar

et al. 2010

A&A

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“…Priest et al, 1994;Mandrini et al, 1996;Longcope, 1998;Santos & Büchner, 2007). Likewise, the intensities of CBPs occasionally show periodic variations as a result of repeated and intermittent magnetic reconnections, with the period ranging from a few minutes to ∼1 hr (Strong et al, 1992;Tian et al, 2008;Kariyappa & Varghese, 2008;Zhang et al, 2012b;Ning & Guo, 2014;Samanta et al, 2015). By performing the potential-field (∇ × B = 0) magnetic extrapolation, Zhang et al (2012b) found that two neighbouring CBPs on 2007 March 16 were associated with two magnetic null points and the corresponding dome-shaped, spine-separatrix topology.…”

Section: Introductionmentioning

confidence: 99%

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Zhang

2016

Sol Phys

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Coronal bright points (CBPs) and jets are ubiquitous small-scale brightenings that are often associated with each other. In this paper, we report our multiwavelength observations of two groups of homologous jets. The first group was observed by the Extreme-Ultraviolet Imager (EUVI) aboard the behind Solar TErrestrial RElations Observatory (STEREO) spacecraft in 171Å and 304Å on 2014 September 10, from a location where data from the Solar Dynamic Observatory (SDO) could not observe. The jets (J1−J6) recurred for six times with intervals of 5−15 minutes. They originated from the same primary CBP (BP1) and propagated in the northeast direction along large-scale, closed coronal loops. Two of the jets (J3 and J6) produced sympathetic CBPs (BP2 and BP3) after reaching the remote footpoints of the loops. The time delays between the peak times of BP1 and BP2 (BP3) are 240±75 s (300±75 s). The jets were not coherent. Instead, they were composed of bright and compact blobs. The sizes and apparent velocities of the blobs are 4.5−9 Mm and 140−380 km s −1 , respectively. The arrival times of the multiple blobs in the jets at the far-end of the loops indicate that the sympathetic CBPs are caused by jet flows rather than thermal conduction fronts. The second group was observed by the Atmospheric Imaging Assembly aboard SDO in various wavelengths on 2010 August 3. Similar to the first group, the jets originated from a short-lived bright point (BP) at the boundary of active region 11092 and propagated along a small-scale, closed loop before flowing into the active region. Several tiny blobs with sizes of ∼1.7 Mm and apparent velocity of ∼238 km s −1 were identified in the jets. We carried out the differential emission measure (DEM) inversions to investigate the temperatures of the blobs, finding that the blobs were multithermal with average temperature of 1.8−3.1 MK. The estimated number densities of the blobs were (1.7−2.8)×10 9 cm −3 .

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“…Coronal bright points (CBPs) are ubiquitous small-scale (10 −40 ) brightenings in the lower corona (Krieger et al 1971;Zhang et al 2001;Kariyappa & Varghese 2008;Huang et al 2012;Kwon et al 2012), which may or may not have Hα counterparts (Zhang et al 2012a). The point-like or loop-like bright features are widely distributed in the quiet regions and in coronal holes (Habbal et al 1990;Kotoku et al 2007;Madjarska & Wiegelmann 2009;Zhang & Ji 2013).…”

Section: Introductionmentioning

confidence: 99%

Reciprocatory magnetic reconnection in a coronal bright point

Zhang

Chen

Ding

et al. 2014

A&A

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Context. Coronal bright points (CBPs) are small-scale and long-duration brightenings in the lower solar corona. They are often explained in terms of magnetic reconnection. Aims. We aim to study the substructures of a CBP and clarify the relationship among the brightenings of different patches inside the CBP. Methods. The event was observed by the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 22−23. Results. The CBP showed repeated brightenings (or CBP flashes). During each of the two successive CBP flashes, that is, weak and strong flashes that were separated by ∼2 hr, the XRT images revealed that the CBP was composed of two chambers, patches A and B. During the weak flash, patch A brightened first, and patch B brightened ∼2 min later. During the transition, the right leg of a large-scale coronal loop drifted from the right side of the CBP to the left side. During the strong flash, patch B brightened first, and patch A brightened ∼2 min later. During the transition, the right leg of the large-scale coronal loop drifted from the left side of the CBP to the right side. In each flash, the rapid change of the connectivity of the large-scale coronal loop is strongly suggestive of the interchange reconnection. Conclusions. For the first time we found reciprocatory reconnection in the CBP, which means that reconnected loops in the outflow region of the first reconnection process serve as the inflow of the second reconnection process.

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Intensity oscillations and heating of the coronal X-ray bright points from Hinode/XRT

Cited by 23 publications

References 19 publications

Temperature variability in X-ray bright points observed with Hinode/XRT

Temperature variability in X-ray bright points observed with Hinode/XRT

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Reciprocatory magnetic reconnection in a coronal bright point

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