NGC 7424

NGC 7424 is a barred spiral galaxy located 37.5 million light-years away in the southern constellation Grus (the Crane). Its size (about 100,000 light-years) makes it like our own galaxy, the Milky Way.  It is called a "grand design" galaxy because of its well defined spiral arms. Two supernovae and two ultraluminous X-ray sources have been discovered in NGC 7424.

 On December 10, 2001, the Australian amateur astronomer Robert Evans discovered SN 2001ig, a rare Type IIb supernova on the outer edge of NGC 7424. At the time of its maximum, the supernova was only three times fainter than the whole galaxy. It must have been a splendid firework!

 It is now believed that indeed this supernova arose from the explosion of a very massive star, a so-called Wolf-Rayet star, which together with a massive hot companion belonged to a very close binary system in which the two stars orbited each other once every 100 days or so. The companion probably periodically stripped the outer hydrogen-rich envelope of the progenitor, accounting for the observed spectral changes, or the periodic mass loss was a result of the intense stellar wind these stars produce.

Image Processing and Calibration: Mark Hanson

24" Planewave CDK f6.5 and L600 Mount, Camera SBIG 16803 Location: SWOS, El Sauce Chile

Data Collection: Hanson, Mazlin, Parker, Forman 2023

Enjoy, Mark