Tuesday, May 17, 2022

AIR day 9 - item 2 (supernova)

The following is a blog post from the Astronomer-In-Residence (AIR) web site, reproduced here. Text and images used with permission.

Day 9 blog entry.

Tuesday 17 May 2022: Imaged a Supernova

At any given moment, there are a number of stars in the universe which are exploding in a rather cataclysmic way. Just visit the Bright Supernova webpage by the Rochester Academy of Sciences.

I had heard about the SN near galaxy Messier 60 so I put it on my list of things to image. Tonight with the clear skies before moonrise, I ramped up to collect some data. I was able to acquire the target as the twilight sky darkened and shoot a number of short sub-exposures. Finished the run around 10:45 PM.

supernova 2022hrs in NGC 4647

Canon 6D Mark II (unmodified), Meade 16-inch ACF LX600, f/8, 10 seconds, 34 sub-exposures, ISO 12800. Stacked with Sequator. Some post-processing in Photoshop.

The supernova is marked with the 2 yellow lines. It is very obvious. The designation is 2022hrs.

Also obvious in the image, down and left of the SN, is the extremely bright core of the elliptical galaxy Messier 60 in constellation Virgo. This galaxy has a published distance of 70.0 million light-years.

Now up and right of the SN is a faint spiral galaxy. Can you make out its spiral arms? This is NGC 4647 from the New General Catalogue. Together, M60 and NGC 4647 are also referred to as Arp 116 from Halton Arp’s collection of unusual galaxies. My trusty SkyTools does not show a distance but The Amazing Wikipedia says around 63 million light-years. So that means, it is in the foreground, or closer than M60.

SN 2022hrs is thought to be inside NGC 4647. The rather amazing thing about this, which you can plainly see, is that a tiny individual star (or binary system), exploding and releasing extraordinary energy, is currently outshining the core of its host galaxy! That’s bright. Really bright. If a supernova went off in our galaxy, we’d probably be able to see it in the day-time!

This supernova is classified as a Type Ia (Roman numeral one-A). Because this class of SN produces a fairly consistent light curve as it brightens and fades away, we can use it as a standard for measuring distance. This means we will be able to refine our distance calculation for the host galaxy. Type Ia supernovae are very helpful for astronomers learning the vast distances that galaxies are from us here on Earth.

OK. Let’s try to estimate the effective brightness at the time of the image run. Conveniently, there is the pair of stars up and left, at a 45 degree angle, and the lower one is about the same intensity. SkyTools says that the star is TYC 00878-0293 1 and it shines at magnitude 11.85. There’s the triangle of stars below M60 and the upper star is GSC 00878-0222. It’s mag 12.24 but unfortunately the data quality for GSC stars is not great. The triangle at the bottom-right of the image has the bright star TYC 00878-0286 1 at mag 11.48 but the SN is not as bright as that one. So, briefly, I believe we can say that SN 2022hrs is around magnitude 12. What do you think?

Finally, if you look very closely in the image, you’ll find more galaxies. Once again, beside the right-angle triangle of stars below M60, there’s a faint fuzzy canted elongated patch of light. That’s galaxy LEDA 1394064. At the bottom-right of the image is the obvious bright galaxy NGC 4638. Look again. Just left of it is an elongated horizontally-oriented fuzzy: NGC 4637.

That was fun!

The Astronomer-In-Residence program is coordinated by the Allan I Carswell Observatory (AICO) at York University with the Killarney Provincial Park Observatory (KPPO).

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