Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines

Abstract

Since their discovery twenty year ago, transition region bright points have never been observed spectroscopically. Bright point properties have not been compared with similar transition region and coronal structures. In this work we have investigated three transient quiet Sun brightenings including a transition region bright point (TR BP), a coronal bright point (CBP) and a blinker. We use time-series observations of the extreme ultraviolet emission lines of a wide range of temperature T (log T = 5.3 − 6.4) from the EUV imaging spectrometer (EIS) onboard the Hinode satellite. We present the EIS temperature maps and Doppler maps, which are compared with magnetograms from the Michelson Doppler Imager (MDI) onboard the SOHO satellite. Doppler velocities of the TR BP and blinker are ≤ 25 km s −1 , which is typical of transient TR phenomena. The Dopper velocities of the CBP were found to be ≤ 20 km s −1 with exception of those measured at log T = 6.2 where a distinct bi-directional jet is observed. From an EM loci analysis we find evidence of single and double isothermal components in the TR BP and CBP, respectively. TR BP and CBP loci curves are characterized by broad distributions suggesting the existence of unresolved structure. By comparing and contrasting the physical characteristics of the events we find the BP phenomena are an indication of multi-scaled self similarity, given similarities in both their underlying magnetic field configuration and evolution in relation to EUV flux changes. In contrast, the blinker phenomena and the TR BP are sufficiently dissimilar in their observed properties as to constitute different event classes. Our work is an indication that the measurement of similar characteristics across multiple event types holds class-predictive power, and is a significant step towards automated solar atmospheric multiclass classification of unresolved transient EUV sources. Finally, the analysis performed here establishes a connection between solar quiet region CBPs and jets.

Quiet-Sun Network Bright Point Phenomena With Sigmoidal Signatures

“…The morphology of the resulting jet is of a bi-directional nature inclined to the LOS as we see the main jet ejecting to the northwest and a smaller one to the south. Although we lack the spectral data that are a signature of bi-directional phenomena Madjarska et al 2004), this uniquely observed sideways morphology, due to the downward magnetic pressure of the overlying horizontal coronal field , suggests a self-similarity between other coronal bi-directional BP events (Orange et al 2014b). In addition, this EUV QS BP sigmoid is predictive of eruptive behavior similar to soft X-ray observations of micro-sigmoids associated with vertical coronal jets (Raouafi et al 2010) and EUV micro-sigmoids leading to micro-CMEs, further demonstrating a multi-scaled selfsimilarity.…”

“…The eruptions show a major jet feature extending from the northwest end of the BP with a smaller jet emanating from the south (jet lifetime = 05:58 ± 0:26 minutes). This antiparallel motion is an observational analog reminiscent of bi-directional jet dynamics that are often observed in spectral data associated with BP phenomena Madjarska et al 2004;Orange et al 2014b). As there were no available Hinode/EIS data (Culhane et al 2007;Kosugi et al 2007) coinciding with the pointing of this event, it was not possible to observe Doppler signatures for the observed jet.…”

“…Coronal and transition region (TR) X-ray and extreme ultraviolet (EUV) bright points (BPs; e.g., Shibata et al 1992Shibata et al , 1996Shimojo et al 1996;Shimojo & Shibata 2000) that predominantly follow the bipole reconnection model as selfsimilar manifestations of large-scale active regions (ARs) are sources of jet phenomena that contribute directly to coronal heating and solar wind mass feeding (Kamio et al 2011;Orange et al 2014b;Tian et al 2014). Although at some coronal heights and temperatures, individual BP loops have been resolved (Kankelborg et al 1996), the spatial resolution of Sun-observing instruments have been insufficient to probe the formation and evolution of BPs due to the existence of unresolved fine structure (UFS) and the dynamics of the plasma and magnetic field environment (Zhang et al 2012).…”

“…BPs are stochastic brightenings that form along the polarity inversion lines (PILs) of strong photospheric magnetic bipole regions (Kankelborg et al 1996;Longcope et al 2001) and have been suggested to be small-scale, self-similar manifestations of ARs (Longcope et al 2001;Orange et al 2014b) due to their compact clustering of loops over distinct bipolar regions. One aspect missing from coronal and TR BP analyses is the ability to predict whether any individual configuration will exhibit eruptive behavior.…”

Dynamic Flaring Non-Potential Fields on Quiet Sun Network Scales

“…The potential for small QS network cool loops to initiate flaring activity (Chesny et al 2013) suggests that identifying the full ensemble of cool, non-potential structures would allow us to explore the physics of non-potential field formation across broad spatial, temporal, thermal, density, and magnetic energy scales. This is akin to the blinker-bright point dichotomy (Orange et al 2014b), where investigating the same phenomena at different temperatures, and investigating different phenomena at the same temperature, uncovers physical processes that may be self-similar between plasma regimes.…”