English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

23 giant flares from 13 active stars (eight RS CVn systems, one Algol system,three dMe stars and one YSO) were detected during the first two years of ourall-sky X-ray monitoring with the gas propotional counters (GSC) of the Monitorof All-sky X-ray Image (MAXI). The observed parameters of all of these MAXI/GSCflares are found to be at the upper ends for stellar flares with the luminosityof 10^(31-34) ergs s-1 in the 2-20 keV band, the emission measure of 10^(54-57)cm-3, the e-folding time of 1 hour to 1.5 days, and the total radiative energyreleased during the flare of 10^(34-39) ergs. Notably, the peak X-rayluminosity of 5(3-9)*10^33 ergs s-1 in the 2-20 keV band was detected in one ofthe flares on II Peg, which is one of the, or potentially the, largest everobserved in stellar flares. X-ray flares were detected from GT Mus, V841 Cen,SZ Psc, and TWA-7 for the first time in this survey. Whereas most of ourdetected sources are multiple-star systems, two of them are single stars (YZCMi and TWA-7). Among the stellar sources within 100 pc distance, the MAXI/GSCsources have larger rotation velocities than the other sources. This suggeststhat the rapid rotation velocity may play a key role in generating largeflares. Combining the X-ray flare data of nearby stars and the sun, taken fromliterature and our own data, we discovered a universal correlation oftau~L_X^0.2 for the flare duration tau and the intrinsic X-ray luminosity L_Xin the 0.1-100 keV band, which holds for 5 and 12 orders of magnitude in tauand L_X, respectively. The MAXI/GSC sample is located at the highest ends onthe correlation.

Large X-ray Flares on Stars Detected with MAXI/GSC: A Universal Correlation between the Duration of a Flare and its X-ray Luminosity