Tag Archives: supernova

supernova hunters and nine lessons for curious people

At the weekend, a bunch of us had fun with a timely challenge – trying to find and follow-up supernovae with supernova hunters as part of the Nine Lessons and Carols for Curious People 24 hour science/music/comedy show organised by Robin Ince and the Cosmic Shambles Network in support of various good causes. Robin and Brian Cox normally run a huge show at the Hammersmith Apollo theatre at this time of year, but this socially distant, marathon show was a suitable replacement.

Robin and musician Steve Pretty somewhere in the middle of the 24 and a bit hour long show – they were on stage throughout! Credit: Cosmicshambles.com

In the run up to the show there was some concern that poor weather in Hawai’i – where the PanSTARRS telescope that provides data for Supernova Hunters is located – might prevent us getting enough data, but in the event skies were clear. Very clear. Which caused a problem as the extra data took a while to get to the servers at Queen’s University Belfast and from there to us, but thanks to heroic efforts from the Supernova Hunters team, I was able to zoom into the show early on and pointed the viewers to the supernovahunters.org site, and classifications started to flow in.

Supernova hunting is a competitive sport these days, and though the early results from volunteers were encouraging, most of what we found was either too faint to make follow-up easy with the telescopes we had on stand by or were objects already identified by other surveys (including the Zooniverse’s friends at ZTF). A brief reappearance on the Nine Lessons big screen (and an email to existing volunteers asking for help) later and we finally had a set of good candidates.

Liverpool Telescope in the Canary Islands, which was responsible for our first follow-up observations. Credit: Liverpool Telescope.

The team – especially Ken Smith and Darryl Wright – worked overnight to arrange follow-up. When I emerged from a few hours sleep observers at the Liverpool Telescope had checked out our most promising candidate – but it turned out not to be a supernova, but rather a less extreme cosmic explosion known as a cataclysmic variable. I marvelled at the fact Robin was still awake – and was coherently interviewing cosmologists, brain scientists and the odd astronaut – and gave an update.

Just after I finished, Belfast’s Ken Smith popped up with the news that observers in Hawai’i using the SNIFS instrument had followed up other targets – and one of them was a real supernova! Better, it was a type 1a – the kind of supernova that can be used to measure the expansion rate of the Universe. Admittedly it was a type 1a-91bg, a rarer type of supernova which is fainter than a normal type 1a, but still useful, and this gave us a payoff for the show.

Spectrum confirming our candidate is a SN1a-91bg associated with a galaxy at redshift z=0.061 – light from an explosion that happened nearly a billion years ago.

Using only that supernova, a bit of maths on the back of an envelope and a few fairly shaking assumptions, we calculated that the Universe was 12.8 billion years old, about a billion short of the commonly accepted value. I wouldn’t throw out the careful systematic analysis of populations of supernova for this simple calculation – but we did get to announce to a bleary eyed comedian that the Universe might be (a little bit) younger than expected.

Just as I went on air a message from Mark Huber, the observer providing data from Hawai’i, confirmed a second supernova – this one a type II, an exploding massive star. It might even be of the same type as the famous 1987A which was spotted in a satellite galaxy of the Milky Way, the Large Magellanic Cloud. Trying to take this in, and convey what was happening quickly was bit much for my sleep-deprived brain but hopefully people realised we confirmed a second supernova!

More importantly, we’ve recorded the results of all of our discoveries in a Astronote published on the Transient Name Server website (the worldwide clearing house for such discoveries). You can read the result of a Supernova Hunters weekend here – and rejoice in the fact that Robin Ince and some of the Cosmic Shambles team are now coauthors on a scientific publication!

I’ll post links to clips from the show when they’re available too, and if you fancy supernova hunting yourself there will be more data on the supernovahunters.org site soon!

Chris

PS Thanks a million to the Supernova Hunters volunteers, and to the team that made it happen – Brooke Simmons (Lancaster), Ken Smith (Belfast), Darryl Wright (Mayo Clinic), Coleman Krawczyk (Portsmouth) and Grant Miller and Belinda Nicholson (Oxford). Michael Fulton and Shubham Srivastav from QUB took the Liverpool Telescope observations, and Michael also led the publication of our AstroNote.

PPS This gives Robin Ince a Erdös Number of, I think, no higher than 5. His Bacon number (according to the Infinite Monkey Cage) is no higher than 3, so this gives him a Bacon-Erdös number of no more than 15! More importantly, as he’s performed music on stage, he must have a Sabbath number, though finding out what it is requires further work – making him one of the rare number of individuals with EBS numbers. A suitable reward for 24 hours of effort.