Can you spot the supernova?
Credit: Forbes/WMKO
It was a dark and stormy night in the city of
Angels. Well, actually it wasn't. But more on that later...
It was a clear night on the summit of Mauna Kea
at Keck Observatory on the 20th March. My colleagues and I were using the Echellette
Spectrograph and Imager (ESI) instrument, which looks at faint objects in the
visible wavelengths, to study star clusters and small galaxies.
I was actually in our special ‘remote ops’ room
at Swinburne University, with my postdoc, Joachim Janz. This is a room decked out with a computer, a
backup computer, a video-link to Keck Observatory and a dedicated Internet
connection. As we are 21 hours ahead of Hawaii, it was a Friday afternoon when
we started observing that Thursday night. My colleagues Sam Penny and Mark
Norris were in the Keck control room, and Aaron Romanowsky was in his remote
ops room at UC Santa Cruz.
Shortly into our night's observing, we noticed a
bright source in the guide camera image that wasn't on our finding chart of
that region. Still we managed to find our target and took a spectrum of it. But
we decided to go back and see if that `new' bright source was still there. Sure
enough it was and it hadn't moved. It was probably a supernova (or an asteroid
coming straight at us!), so I decided to get a 5min spectrum with ESI. And
indeed we had found a supernova—a type Ia to be exact. Type Ia supernovae are
fairly rare in the nearby Universe and represent the explosion of at least one white
dwarf star in a binary system. It is this same type of supernova that led to
the discovery of Dark Energy in the Universe using the Keck Observatory, and
three Nobel prizes.
Our supernova is located in the outskirts of a
galaxy some 100 million light years from us—so it exploded 100 million years
ago but the light only reached us that night.
I later found out that an automated telescope on
the Palomar Mountain overlooking Los Angeles detected the supernova shortly
before us. They also managed to get a spectrum but that was taken after our
Keck II/ESI spectrum. The exciting thing is that both the Palomar Observatory
and ourselves managed to observe the supernova in the 1-2 weeks before it
reaches its maximum brightness (and then fades steadily after that).
The supernova has been given the designation
SN2014ai.
All in all, not bad for a late night at the
office...
By Prof. Duncan Forbes
Duncan Forbes is a professor of astronomy at
Swinburne University in Melbourne, Australia, and a 2014 Evenings with
Astronomers presenter at the signature Friends of Keck lecture series. Swinburne
astronomers are awarded time for their research on Keck Observatory
through an agreement with the California Institute of Technology.
Source: W.M. Keck Observatory
