A Supernova Story

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SN 2009ab as seen by the AlbaNova Telescope in Stockholm, Sweden. Credit: Magnus Persson, Robert Cumming and Genoveva Micheva/Stockholm University

Have you ever discovered a supernova? Well, I haven’t, but I can only imagine finding a star that has blown itself to smithereens must be pretty exciting. At least that’s what I thought, anyway….

Seemingly, a fair amount of folks must be out there who have found supernovae. In 2008 alone, 278 supernovae were found, one by a 14-year old girl. But 2008 was a really slow year in the supernova department. In 2007, 584 were discovered – a record number – and in 2006, 557 supernovae were spied by astronomers, both professional and amateur. 40 have been found so far in 2009. But even with those fairly big numbers, I still gotta believe that finding a supernova must be absolutely incredible. So when someone I knew, Robert Cumming from Stockholm University in Sweden, recently played a part in finding a supernova, I emailed him my congratulations. Imagine my surprise when he replied, “It’s no big deal, really.”

But Robert, it’s a SUPERNOVA!

I had heard of Scandinavian stoicism, but this was off the charts! Besides that, I knew Robert is not originally from Sweden.

So, I begged him to tell me all about it.

“Well, since you ask,” he said with a smile. Okay, maybe, just maybe he was more excited than he was letting on.

Here’s the story of how Supernova 2009ab was discovered:

“I’ve observed a few supernovae before and I’ve had my name on the odd IAU circular, but this is the first time I’ve been one of the first to actually confirm one,” said Robert, with just a hint of excitement in his voice.

On February 8, the Katzman Automatic Imaging Telescope (KAIT), a 30-inch fully robotic telescope at the Lick Observatory on Mt. Hamilton in California discovered a bright spot not seen before in the outskirts of the spiral galaxy UGC 2998, 150 million light years away. Astronomers from KAIT wanted to make a second observation to verify, but bad weather made it impossible for them to confirm that the new object was not an asteroid or instrumental error. So, the KAIT astronomers requested observations from other telescopes around the world.

Magnus Persson, also from the Stockholm University was getting ready to do some observations using the University’s AlbaNova Telescope, when Robert received an email from KAIT about needing confirmation observations.

“I knew Magnus was going to be observing – he was planning to take some pictures of the Crab nebula for a colleague,” said Robert. “And I had this mail from the KAIT in California.”

So, the two set to work in an effort to locate the possible supernova.

Robert and Persson used different filters and took a few images of galaxy UGC 2998. “The supernova was right there on our first 45-second exposure – we were kind of amazed!” he said.

The two astronomers from Sweden were able to establish that the new light source showed all the signs of being a supernova. The supernova shines in a blue color, in contrast to the stars in the galaxy which are generally old and red, and the other stars in the image which lie in our galaxy. Shortly after the explosion, such a supernova emits as much energy as the entire host galaxy.

“We did the observations properly, and then I picked the best data to make very rough photometry, got comparison magnitudes from Gregor Dusczanowicz, Sweden’s amateur supernova discoverer, talked to a colleague to check we hadn’t forgotten anything important, and mailed off the measurements to the Central Bureau for Astronomical Telegrams.”

Other telescopes have now observed SN 2009ab, but the AlbaNova telescope was the first to successfully take images and confirm it as a new supernova. The following day, astronomers on the Canary Islands took a spectrum using the considerably bigger Telescopio Nationale Galileo and were able to determine the supernova was of type Ia, that is a white dwarf star which had exploded in a binary system. As Magnus’ and Robert’s confirmation was published in an astronomical telegram, the new supernova was named SN 2009ab, this year’s 28th supernova.

So, SN 2009ab is a story of the cooperative camaraderie that exists between astronomers, working together to verify and cross-check their findings. Here’s a list of everyone who contributed in the discovery of this supernova.

It’s also the story of a new telescope in an unlikely location being used to make new and exciting — yes exciting –discoveries. The Stockholm University Department of Astronomy uses the AlbaNova telescope, a 1-meter reflector, mainly for education and instrumental development. Robert said the plan is to use the telescope to do environmental monitoring, using LIDAR to monitor ozone and particle pollution in the city.

But Robert said the discovery of the supernova shows it is also possible to do scientifically interesting astronomical observations with the telescope, despite the limitations from Stockholm’s bad weather and light pollution.

“Our site is right in the city, so our sky brightness is scary. So far we haven’t measured just how bad it is, so it was a really nice surprise to get something out of it,” he said.

“The telescope is still pretty new, and with the Stockholm weather lately the experience of observing at all is pretty exciting,” Robert said. “And it is exciting that the telescope is now in full use. If we can do observations like these, we can do much more.”

So finally, I got Robert to admit he was excited. But the Scandinavian modesty and stoicism quickly returned.

“But the supernova itself is no big deal really, and our picture isn’t that good,” he said. “Many amateurs take pictures better than ours.”

Well, Robert, I’m excited for you! Congratulations!

Learn more about the AlbaNova Telescope.

Listen to Robert Cumming on the March 2 “365 Days of Astronomy” podcast, “Astrosvenska for Anyone: Space Swedish in Ten Ridiculously Short Lessons” (you’ll enjoy hearing his “Swedish” accent).

Robert Cumming also writes for a Swedish astronomy website, Populär Astronomi