Description
Chair: W. Iwakiri (Chiba Univ.)
X-ray Imaging and Spectroscopy Mission (XRISM) has two X-ray instruments. Resolve, an X-ray microcalorimeter, has an extreme energy resolution of 5 eV at 6 keV. Xtend, an X-ray CCD array, has a large field of view (FoV) of 38 arcmin square, which gives us opportunities to observe many serendipitous sources. We developed the XRISM/Xtend Transient Search (XTS), a project to quick search and fast...
Since MAXI's launch in 2009, we have continuously surveyed stellar flares. The flare sample now exceeds 200 and has been found to originate from about 30 active stars, including RS CVn systems, Algol systems, dMe stars, dKe stars, YSOs, and undefined-type stars. The observed parameters of these MAXI flares are: luminosity of 10^31-10^34 erg s-1 in the 2-20 keV band, emission of 10^54-10^57...
We detected a giant X-ray flare from the RS-CVn type binary star UX Ari using MAXI on 2020 August 17 and started a series of NICER observations 89 minutes later. For a week, the entire duration of the flare was covered with 32 snapshot observations including the rising phase. The X-ray luminosity reached 2$\times$10$^{33}$~erg~s$^{-1}$ and the entire energy release was $\sim 10^{38}$~erg in...
LEIA (Lobster Eye Imager for Astronomy) detected a new X-ray transient on November 7, 2022, identified as a superflare event occurring on a nearby RS CVn-type binary HD 251108. The flux increase was also detected in follow-up observations at X-ray, UV and optical wavelengths. The flare lasted for about forty days in soft X-ray observations, reaching a peak luminosity of ∼ 1.1 × 10^34 erg s^−1...
The Einstein Probe (EP) is an interdisciplinary mission of time-domain and X-ray astronomy. It was launched into orbit from the Xichang satellite launch centre on January 9, 2024. From 2024 July the commissioning and calibration phase was successfully completed and the nominal operations phase has started. The Wide-field X-ray Telescope (WXT), one of the two main payloads on board EP, is to...
XRISM PV observation of the Galactic Center detected an interesting transient source named CXOU J174610.8-290019 within the Xtend FoV. The spectrum shows an intensity ratio of Fe-XXVI and Fe-XXV corresponding to kT>20 keV in comparison with a moderate bremsstrahlung continuum of kT~5 keV. We present the results of spectral and timing analyses.
