Ok, I didn’t personally - but the news stories all mention that this guy watching the sky saw it start, alerted everyone, and next thing you know all eyes are glued to it.
For how long? Was it a giant 'splosion that lasted 20 minutes? An Hour? A day or two?
If I’m looking at this, what’s the time between “oh look at the bright light” to “well that was interesting!”
Well, the actual explosion part of a supernova is over in a matter of seconds.
But it is a really big boom. The expanding shockwave from it can heat nearby gas and cause it to glow. In some cases this can go on for years. This one was watched for 11 years.
EDIT: This page has a graph showing they can last for months.
Since a supernova visible to the naked eye hasn’t occurred since before the invention of the telescope, readers may be wondering why this isn’t front page news everywhere.
As this article shows, what was actually viewed was a five minute burst of x-rays. Those wouldn’t have been “seen” either, except as readings on a screen, probably a spike in a graph later translated into a visual depiction as in the linked article.
Better to say that they recorded the x-ray burst in real time. Nobody saw anything. They might “see” something in a month’s time when the supernova has brightened enough in the visible band to be detected by optical telescopes. The x-ray spike was predicted to only last around five minutes and this seems to confirm that. This spike is only the first tiny bit of a much longer event that will go through much of the EM spectrum.
Good article about the event by former doper the Bad Astronomer.
Technically, as Angua noted in passing in one of the threads about it, the “Civil War supernova” was in fact probably visible to the naked eye, but at 26-28,000 LY away, would have appeared as one additional new fifth magnitude star in the midst of the Milky Way (the visual phenomenon, not the galaxy), and hence unnoticeable to anyone not specifically looking for it – as in fact it was not noticed.
Obligatory supernova-related Futurama quote:
“I’ve never seen a supernova explode, but if it’s anything like my old Chevy Nova, it’ll light up the night sky!”
~Fry
So, as far as we can tell, no one saw this supernova “as it happened” (ie, 27,000-ish years ago, but to us, 140?) We have documented sightings of other, larger, supernovas exploding, right? From hundreds to thousands of years ago? I seem to remember some famous Chinese writings about one.
The Crab Nebula? Wiki link.
The last supernova in our galaxy (that was actually noticed at the time) was in 1604, I think, in the constellation of Ophiuchus. There was also a very bright one in 1572 in Cassiopeia. You could have seen both in the course of a single lifetime.
This is the first time we have seen a supernova as it happened rather than at some time after it happened (not counting the transit time but from our perspective).
Yes, astronomers have witnessed many supernovas but always coming to them some days or months after it occurred. Remember various wavelengths arrive before visible light from the supernova arrives.
In this case a satellite taking x-ray measurements just happened to be pointing at the right part of the sky to record an x-ray burst. The astronomer running the experiment recognized this as a possible precursor to the rest of the supernova light reaching us and got the word out so many astronomers were looking at the right spot when the first bits of the rest of the supernova arrived. This allowed them a glimpse at the actual moments of a supernova unfolding which to them is apparently a huge thing and something worthy of a good deal of excitement. This has never happened before in the history of astronomy.
Supernova 1987a was visible to the naked eye,
It wasn’t in our galaxy, though, and only got up to third magnitude as seen from Earth. Not very impressive to non-astronomers.
Two questions, then.
Is it possible to have a chain reaction of supernovae? Say inside a globular cluster?
We’re talking about 88MM light years away for 2008D, right? Would there be any reason to believe that the nature of supernovae had changed over that time and that one that happened in our neighborhood (50ly away) would function the same way or differently?
Why on earth (or off it) would the laws of physics, which govern the behaviour of supernovae, have changed over that period? 88 million years is *nothing *in astronomical terms. There’s no reason I know of to believe the laws of physics have *ever *changed.
The claim I was quoting didn’t specify the Galaxy, though. And 3rd magnitude is bright enough that as soon as the astronomers who discovered it saw the plates (and sent off the telegram), they went outside, looked up, and were able to go “Yeah, there, see it?”.
I assume this means supernovae emit certain wavelengths first, as opposed to certain wavelengths traveling faster than light?
Nothing travels faster than light. It’s just that certain processes create different wavelengths at different times in the progression of a supernova.
X-rays are produced at the beginning. Visible light takes longer to reach the levels necessary to spot the supernova at such a distance, about a month according to one of the linked articles, IIRC.
Other particles arrive as well. Neutrinos don’t interact with anything so they can cut through the explosion like it’s not there. They are normally the first indicator that a supernova has occurred. We should be seeing some results from the neutrino detector labs on this.
Bad astronomy question removed due to quick resolution with brief Google search.
Speak for yourself!
I was touring New South Wales in February of 1987 and had stopped at a little town named Coonabarabran. I passed a newstand and noticed the cover story on Time magazine about a new, naked eye supernova. I had taken an astronomy class in college and had a layman’s understanding of what was going on, so I was very excited and started to read the article on the spot.
The article started out with the obligatory gee-wiz kaboom descriptions, but quickly turned to reports from what it described as the nerve center for astronomical inquiry into the new object at an observatory just outside of Coonabarabran Australia.
On a lark I found directions to the observatory and drove straight up to it. It wasn’t a media circus but it was certainly abuzz with activity. The astronomers were very excited, yet incredibly gracious about taking time to talk to some yokel American who just waltzed in. I wasn’t very familiar with the southern skies so I knew I’d need a good description of where to look and they were very obliging with a hand-drawn chart.
I could hardly wait for the sun to go down and when it did I quickly realized the chart was unnecessary. The week before I’d been on the beach looking at the Magellenic Clouds for the first time in my life. Now I looked again and THERE IT WAS. It seemed about as bright as Jupiter, and I was certainly impressed!
Until the champagne runs out.