Investigation of Hot X-ray Points (HXPs) Using Spectroheliograph Mg XII Experiment Data From CORONAS-F/SPIRIT

TL;DR

This study analyzes high-temperature, compact X-ray points (HXPs) observed by the Mg XII spectroheliograph on CORONAS-F, revealing their physical parameters, temperature variations, and energy release characteristics, distinguishing them from other solar microevents.

Contribution

It provides detailed measurements of HXP properties, their temperature evolution, and energy estimates, offering new insights into their nature and distinction from similar solar phenomena.

Findings

HXPs have plasma temperatures of 5-40 MK.

Lifetimes of HXPs range from 5 to 100 minutes.

Energy release in HXPs does not exceed 10^{30} erg.

Abstract

Observations in the Mg XII 8.42 AA line onboard the CORONAS-F satellite have revealed compact high temperature objects-hot X-ray points (HXP)-and their major physical parameters were investigated. Time dependencies of temperature, emission measure, intensity, and electron density were measured for 169 HXPs. HXP can be divided into two groups by their temperature variations: those with gradually decreasing temperature and those with rapidly decreasing temperature. HXPs plasma temperatures lie in the range of 5-40 MK, the emission measure is $10^{45}$- $10^{48}$ cm$^{-3}$, and the electron density is above $10^{10}$ cm$^{-3}$, which exceeds the electron density in the quiet Sun ($10^8$-$10^9$ cm$^{-3}$). HXPs lifetimes vary between 5-100 minutes, significantly longer than the conductive cooling time. This means that throughout a HXP's lifetime, the energy release process continues, which helps to maintain its high temperature. A HXP's thermal energy is not greater than $10^{28}$ erg, and the total energy, which is released in HXPs, does not exceed $10^{30}$ erg. HXPs differ in their physical properties from other flare-like microevents, such as microflares, X-ray bright points, and nanoflares.