Chromospheric evaporation in sympathetic coronal bright points

TL;DR

This study provides direct evidence of chromospheric evaporation in sympathetic coronal bright points caused by thermal conduction from a primary bright point, using high-resolution soft X-ray imaging from the Hinode spacecraft.

Contribution

First direct observation of thermal conduction-driven chromospheric evaporation in sympathetic CBPs using high-cadence SXR imaging.

Findings

Thermal conduction front propagates from primary to sympathetic CBPs at ~138 km/s.

Upflows indicating chromospheric evaporation observed at ~76 km/s and ~47 km/s.

Thermal conduction is identified as the cause of gentle chromospheric evaporation in sympathetic CBPs.

Abstract

{Chromospheric evaporation is a key process in solar flares that has extensively been investigated using the spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings associated with the primary flares that have recently attracted dramatic attention.} {We intend to find the evidence for chromospheric evaporation and figure out the cause of the process in sympathetic coronal bright points (CBPs), i.e., remote brightenings induced by the primary CBP.} {We utilise the high-cadence and high-resolution SXR observations of CBPs from the X-ray Telescope (XRT) aboard the Hinode spacecraft on 2009 August 23.} {We discover thermal conduction front propagating from the primary CBP, i.e., BP1, to one of the sympathetic CBPs, i.e., BP2 that is 60$\arcsec$ away from BP1. The apparent velocity of the thermal conduction is $\sim$138 km s$^{-1}$. Afterwards, hot plasma flowed upwards into the loop connecting BP1 and BP2 at a speed of $\sim$76 km s$^{-1}$, a clear signature of chromospheric evaporation. Similar upflow was also observed in the loop connecting BP1 and the other sympathetic CBP, i.e., BP3 that is 80$\arcsec$ away from BP1, though less significant than BP2. The apparent velocity of the upflow is $\sim$47 km s$^{-1}$. The thermal conduction front propagating from BP1 to BP3 was not well identified except for the jet-like motion also originating from BP1.} {We propose that the gentle chromospheric evaporation in the sympathetic CBPs were caused by thermal conduction originating from the primary CBP.}