Today's XRISM: 20240607
We are conducting Target of Opportunity observations of SS Cygni, which has brightened to magnitude 9 in optical light!
SS Cygni is a type of white dwarf known as a "dwarf nova" and experiences outbursts every few dozen to several hundred days. These outbursts are thought to occur when the inner edge of the accretion disk, created by material falling toward the white dwarf, approaches the surface of the white dwarf.
The brightness of the star in the visible light spectrum is recorded daily in the database of the American Association of Variable Star Observers (AAVSO) < https://www.aavso.org/> with the help of amateur astronomers.
The Target of Opportunity observation by XRISM was also initiated based on the confirmation of this outburst in the AAVSO database.