Speaker
Description
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 cm-3, temperature of 1-16 keV, e-folding time of 6-360 ksec, radiation energy during the decay phase of 10^34-10^39 erg. These parameters indicate the upper limit of the stellar flare. The radiation energies are orders of magnitudes greater than the largest flares occurred at the Sun - the solar flare has a maximum of 10^32 erg. These differences raise the question of how such huge amounts of magnetic energy are stored and where these events originate. One of the keys to understanding this question may be multi-wavelength observations, since the flaring plasma will be essentially multi-temperature. With this idea, we have installed three optical telescopes on the rooftop of a building at Chuo University Korakuen campus, which is called CHAO (CHuo-university Astronomical Observatory). CAT (Chuo-university Astronomical Telescope) and SCAT (Spectroscopic Chuo-university Astronomical Telescope) have been executing photometry and low-dispersion spectroscopy, respectively, and PHAST (Photometric And Spectroscopic Telescope) can simultaneously perform photometry and high-dispersion spectroscopy, with very fast tracking capability for transient detected with MAXI at a world-class driving speed of 20 degrees per second. Despite that the Korakuen campus is located at a downtown Tokyo in Japan and the diameters of the three telescopes are just in the range of 26-41 cm, we have been accumulating good examples of the flares from MAXI stars. We will review the dynamics, the situation at the flare onset, and e-folding time, obtained with CHAO and the other large telescopes at the followup and monitoring observations of MAXI flare stars.
