Pinwheel Galaxy Supernova At Brightest; Comet Garradd Beckons

Thomas Nelson of Duluth put together before-and-after photos of the Pinwheel Galaxy to show how what a difference the supernova makes. He took an image in May before the eruption and combined it with one taken this month by William Wiethoff.

I am jazzed up. I finally got a picture of the supernova SN 2011fe in the Pinwheel Galaxy last night using only a telephoto lens on a tracking mount. The moon is now nearly at last quarter and doesn’t flood the sky with light like it does around full phase. This provides us all with another round of opportunities to see the supernova before it fades. For almost a week, it’s been humming along at magnitude 9.9. As you can tell from the before-and-after sequence above, it’s hard to miss!

The path starts at bright Mizar and zigzags its way up to the supernova, which lies just beyond the arrow tip in the Pinwheel Galaxy in this photo taken last night (Sept. 16). Alkaid and Mizar are the two stars at the end of the Big Dipper's Handle. Details: 150mm lens, f/2.8, ISO 800 and 2-minute exposure. Photo: Bob King

Here’s a link to two maps to help you find the SN 2011fe or you can use the photo above. It will soon begin to fade, so take some time the next clear night and treat your eyes to a big blast. You can either use big binoculars (20 x 80mm or 30 x 80mm on up), a small telescope or even a spotting scope to see it.

The life cycle of a star on its way to becoming a Type Ia supernova. This variety of supernova evolves in close double star systems, where the companion is ejected into space after the powerful explosion. Credit: NASA/ESA

Type Ia supernovae like the Pinwheel star are produced when a white dwarf star gobbles matter from a close companion star. When critical mass is reached, the increase in pressure and density within the dwarf initiates the fusion of carbon atoms in the core which releases enough energy to completely and explosively burn through the star. Try to picture a thermonuclear bomb the size of a large city going off to grasp the power of this stellar .

A light curve for a typical Type Ia supernova showing how the star's brightness (left) axis varies with time. Credit: NASA/HST/High-z SN Search Team

The star suddenly rises from invisibility to maximum light in the space of a few weeks then takes several months or more to fade away. Type Ia explosions are bright enough to be visible across billions of light years. That and their similarity to one another allow astronomers to use them as “standard candles” to determine distances to galaxies billions of light years away.

Look for Comet Garradd to the west of the Summer Triangle asterism comprised of Vega, Deneb and Altair. The comet is near a small triangle of faint, naked eye stars in Hercules. The map shows the sky facing south-southwest at nightfall and the comet's position at 5-day intervals. Created with Chris Marriott's SkyMap

I also looked at our good friend Comet Garradd last night which continues shining around 7th magnitude high in the southwestern sky. I’ve prepared the map above you can use to find the comet between now and mid-October.

Because of viewing perspective involving the combined motions of Earth and the comet, Garradd will appear to slow down in the coming weeks, remaining in one small area of the sky near the trio of faint naked eye stars 109,110 and 111 Herculis in the constellation Hercules. It’s faintly visible in binoculars and a pretty sight with a fat tail pointing southeast in a telescope.

2 Responses

  1. Jim

    Hi Bob,

    I was able to see the Supernova and comet Garrard tonight. The supernova is quite bright. I could not see with binoculars, but I got it easily with the scope once I sorted through the stars visible in the view. I could just barely make out the galaxy with the light pollution present. Thanks for the picture in the blog. That helped.

    Comet Garrad was surprisingly bright. It looks like I could see a bit of tail through the scope.

    Take care,

    1. astrobob

      Hi Jim,
      Great to hear it. We had clear skies last night but with moonlight. Tonight was the first dark night without but it’s cloudy. I’ve been busy this week with covering our big forest fire to the north. I went to the fire line near the Island River, very close to where a friend and I paddled in August to a pictograph site on the river.

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