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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We probed stellar X-ray activity over a wide range of stellar parameters,using {\it Chandra} and LAMOST data. We measured the X-ray-to-bolometricluminosity ratio ($R_X = L_X/L_{\rm bol}$) for 484 main-sequence stars, andfound a bimodal distribution for G and K types. We interpret this bimodality asevidence of two sub-populations with different coronal temperatures, which arecaused by different coronal heating rates. Using the metallicity and velocityinformation, we find both of the two sub-populations are mostly located in thethin disk. We find no trend of $R_X$ with stellar age for stars older than$\sim$ 4 Gyr; there is a trough in the $R_X$ vs age distribution, with thelowest range of $R_X$ appearing at ages around 2 Gyr. We then examined thecorrelation between $R_X$ and $R_{\rm H\alpha}$ (proxy of chromosphericactivity): we find that the two quantities are well correlated, as found inmany earlier studies. Finally, we selected a sample of twelve stars with X-rayflares, and studied the light-curve morphology of the flares. The variety offlare profiles and timescales observed in our sample suggests the contributionof different processes of energy release.

A Combined Chandra and LAMOST Study of Stellar Activity