Image: The M51 supernova (arrowed) as imaged by BBC Sky at Night Presenter Pete Lawrence. Source & hi-res version: Universe Today. Used with permission.
On May 31, a bright supernova erupted in M51 — more famously known as the “Whirlpool Galaxy” — located approximately 25 million light-years from Earth. Amateur astronomers were the first to spot the rapidly brightening object — bright enough to be imaged by backyard astronomers.
This is the second supernova to be observed in M51 over the past six years (and the third in 17 years), but this event is also notable in that a professional team of astronomers were alerted to the supernova’s presence through social media.
In fact, through the serendipitous combination of being in the “right place at the right time” and Twitter, astronomers from the University of California, Berkeley were able to quickly grab the spectrum of light being blasted from the site of violent stellar death.
WATCH VIDEO: Discovery News unlocks the mysteries of stars and finds out why a star’s age matters.
A New Star in M51
It all began on May 31, when French amateur astronomer Amédée Riou detected a “new” star in CCD images of the Whirlpool Galaxy. Riou’s discovery was corroborated independently by Thomas Griga in Schwerte, Germany, the following day. By June 2, it had been confirmed by Tom Reiland in Glenshaw, Pennsylvania, and Stéphane Lamotte Bailey in France.
Images of the supernova candidate were beginning to circulate on the internet and Daniel Fischer, editor of the astronomy breaking news website “Cosmos4U,” tweeted the following message:
“How cool is that?! I report the probable M 51 supernova to a German astro list – and immediately a great pic is taken:
It just so happened that Derek Fox, Assistant Professor at Penn State University Astronomy and Astrophysics, noticed Fischer’s tweet and forwarded the alert to Berkeley postdoctorate researcher Brad Cenko.
As luck would have it, Cenko and his supervisor, Alex Filippenko, Professor of Astronomy at
the the University of California, Berkeley, happened to be in the best possible location on the planet: controlling one of the twin 10-meter telescopes at the world-renowned Keck Observatory on the summit of Mauna Kea, the highest peak in Hawai’i and home to 13 telescope systems.
“To be at the world’s greatest telescope at the time [a very bright, young supernova is] reported is not a very frequent occurrence!” Filippenko told Discovery News.
“We happened to have a Japanese film crew filming me for a documentary they’re doing on dark energy and the accelerated expansion of the universe,” he said, “so there was this team there who were provided with really great footage.”
Unfortunately, despite getting a fortuitous tip-off via Twitter about a commencing supernova in an easily observable galaxy, the high-altitude Hawaiian weather wasn’t playing ball.
“We were sitting there, very frustrated as the telescope had been shut down just before I was able to get a spectrum — we were literally pointing directly at the object and the operator wanted to keep us open but said ‘Look folks, the humidity is 100 percent and fog is beginning to form.’ Of course I couldn’t force the operator to [keep the dome open]!”
When a Stellar Core Collapses…
Fortunately, two hours later, conditions improved enough to quickly point the Keck 1 telescope at M51 to gather some spectroscopic data.
“We finally got that and we opened, got a quick spectrum and the operator said ‘We have to close down again,’ but that was sort of OK… well it wasn’t OK as I couldn’t get the rest of my science done! But at least we got this one spectrum. There was a lot of excitement! And [the Japanese film crew] filmed all of it.”
The few minutes of spectroscopic data from Keck 1 confirmed the M51 brightening was in fact a “Type II” supernova.
“We classified the supernova as a Type II, which comes from a massive star at least 8-times the mass of the sun and it explodes through a mechanism of core collapse and rebound,” Filippenko explained. “So the iron core collapses and the outer parts rebound and get blown away.”
The Keck 1 analysis also revealed some interesting details about the shock wave that was generated after the detonation. “The shock wave has material moving at a variety of different speeds (typically faster farther out),” Brad Cenko told Sky and Telescope. “The hydrogen that we see moving toward us at 17,600 km per second [11,000 miles per second] is probably a pretty good proxy for the fastest material in the outflow.”
Worldwide Social Astronomy
To catch a supernova in the act is the “Holy Grail” for amateur and professional astronomers alike. To understand the mechanisms behind how supernovae evolve, the faster information about a supernova event can be relayed to the world, and the more telescopic systems that can quickly slew on-task, the better.
In this era of instant social media communications, tools such as Twitter are becoming a valuable asset to astronomers, complementing — and, in this case, superseding — traditional means of transmitting breaking astronomical news.
“This is the first time that we’ve been alerted via a tweet,” said Filippenko. “We’ve been alerted many times via email, and in a sense, I was alerted via an email message, but it was from a colleague who was alerted through a tweet.”
“To my knowledge, that is unprecedented.”
Special thanks to Larry O’Hanlon, Communications and Public Programs Officer at Keck Observatory, for tipping me off about all the excitement atop Mauna Kea!