I know, I know, it really went supernova 21 million years ago, and its light is finally reaching us. But let’s have fun with this because this is the closest supernova event to us that we have seen in a decade. It has received the designation Supernova 2023ixf.
On May 19, amateur astronomer Koichi Itagaki spotted a new point of light in the Pinwheel Galaxy (also called Messier object 101, or simply M101). Here’s his original discovery photo:
As of early this morning (about 1 A.M. Eastern), the supernova’s magnitude had risen to an estimated 11.9, bright enough to see with a 4.5-inch telescope. And it’s getting brighter fast, because by 3:20 P.M. Eastern today it clocked in at magnitude 11.0. So it got roughly 2.5 times brighter in less than 24 hours!
It’s expected to continue to brighten over the next few days, and we’ll see where it tops out. Then it should hang around for a few months of observation before it fades away.
Patrick Wiggins of the University of Utah was photographing M101 over successive nights, and he just so happened to catch it in the act:
We’ve got a nice gallery full of images from people around the world here at Rochester Academy of Science, so do check that out to see what people have captured. Some great imagery also at EarthSky.
More images will emerge in the coming days, to be sure, because M101 is one of the most frequently photographed galaxies, and that’s because it’s spectacular!
You can see another nice full-screen picture at NASA’s APOD (Astronomy Picture of the Day) site, a snippet of which I’ve blown up here:
The APOD page gives a little more description:
Rapid followup observations already indicate that SN 2023ixf is a Type II supernova, an explosion that occurs after a massive star runs out of nuclear fuel and collapses. [...] Studying such a close and young Type II supernova may yield new clues about massive stars and how they explode.
And Bob King at Sky & Telescope elaborates:
Massive suns fuse simpler elements into more complicated ones all the way up to iron. Each step liberates energy that pushes back against the force of gravity and stabilizes the star. But the buck stops at iron. Stable as a proverbial brick house, it takes crazy amounts of energy to fuse it — energy the star can't produce. No longer able to beat back gravity's crush, the star suddenly collapses. Material falling inward bounces off the shrinking core, creating shock waves that rebound outward and rip the supergiant apart in a titanic explosion. Type II events leave a neutron star or black hole in their wake — the tiny remnant of a life lived bigly.
Type II supernovae need to be between 8 and 50 times the mass of the Sun to undergo the type of collapse and explosion that they do. And indeed, the spectrum we have for supernova 2023ixf identifies it as one of these:
The giant hydrogen peak at 6563 angstroms (or 656.3 nanometers), is the dead giveaway, because other types of supernovae do not show that. That’s also true of the other hydrogen peaks at 4101, 4340, and 4861 angstroms, which are all clearly visible. So Type II it is.
If you’re wondering where in the sky M101 is, it’s just off the handle of the Big Dipper, which is highest in the sky right here in Spring:
We can thank Mr. Itagaki for making the great catch. Here he is with the telescope he used to discover Comet Itagaki back in 2009. He’s pretty good at this sort of thing.