A big honking exploding star

September 3, 2014 • 9:34 am

V838 Monocerotis is a star that blew up about 20,000 years ago, but whose light just reached Earth in 2002, when its sudden increase in brightness was noticed by an amateur astronomer.  It became a million times brighter than the Sun, and the diameter of the explosion was as large as the diameter of Jupiter’s orbit around the sun.

In today’s New York Times, Dennis Overybye has a piece on this star, called one of the most stunning astronomical events ever seen. What is most stunning, though, is the 2.5-minute video, which you can access (as well as the article) by clicking on the screenshot below.

Screen Shot 2014-09-03 at 11.26.46 AM

An excerpt from the piece:

Astronomers are still arguing and speculating about what happened. Measurements of the star’s light output showed that the explosion happened in three stages, flaring and then dimming three times from January to March 2002.

Some scientists have suggested that V 838 swallowed planets in its orbit. Others have proposed that V 838 was actually two stars orbiting each other, and that the explosions were a result of their atmospheres merging into a common envelope of gas.

The answer could be relevant to our plight. Someday, a few billion years from now, the sun will run out of fuel and become a red giant,swallowing Mercury and frying the Earth and Venus.

Whatever it was that made V 838 erupt, astronomers are still watching it go.

The star, it turns out, is embedded in a cloud of dust trillions of miles across. Most likely, astronomers say, these wreaths of dust gave rise to V 838 perhaps four million years ago. They would usually be invisible, but the pulses of light traveling outward from the explosion have illuminated shells of dust previously kicked off the star. The Hubble Space Telescope has recorded images of these so-called light echoes, and viewing them in succession calls to mind the explosion of Darth Vader’s Death Star — except that in this case, nothing is moving but the outward-rushing light wave; the dust is standing still.


39 thoughts on “A big honking exploding star

  1. Truly amazing. I especially like the graphic at around 1:08 showing the way in which the light reflecting off of clouds of dust causes the echoes. I remember reading about the same phenomenon in an Astronomy textbook in college and not really being able to picture the process. The video made it very clear to me.

  2. Those light echoes are neat – it isn’t dust expanding, but light illuminating dust that was already there!

    I often wonder if Betelgeuse has already gone nova.

    1. Fun fact: you can’t ask an astronomer that. Due to convenience, uncertain distances and pesky relativistic effects they, quite sensibly, use the reference frame of “here and now”.

      So you have to ask them: will Betelgeuse go nova within X years? (Where X < Y, Y being the distance in lightyears.)

      They will probably answer, to riff off Riff of Sluggy Freelance, "I dunno."

  3. Not quite accurate. The dust is definitely not standing still. Even if V 838 were not influencing the dust around it all, it would still not be standing still. Comparatively, the light that is illuminating the clouds is of course moving much faster than the dust, but even that radiation is affecting the movement of the dust.

    So there is a disconnect between the advance of the light from the explosions through the cloud compared to the movement of the dust, but the dust sure as heck ain’t standing still.

      1. 🙂

        I’m just in that kind of mood. Last night I watched the 2nd episode of a new BBC documentary about amazing animal senses. I was expecting it to be pretty good because it was BBC as opposed to US network crap. Turns out it really was just as bad, in just the same ways that most US made docs are made.

        Bad science, bad explanations, drama over truth, let alone accuracy, and low signal to noise ratio. What’s up with the BBC?

        1. Maybe it’s BBC America and they just gave you a shit show because they figured that’s what Americans like. I get BBC Canada after having the for realz BBC by accident for a couple days and I was disappointed.

    1. In all fairness, the velocity of the dust is (I’m guessing) five or six orders of magnitude less than the velocity of light. So the dust is standing still in the same sense as a glacier stands still while you fly over it in an airplane. All the motion you see is due to the light (or the airplane), and none of it to the dust (or the glacier).

      My quibble is different: the star expanded to the size of Jupiter’s orbit, but the explosion didn’t stop there. Its optical wavefront and acoustic shockwave will go on expanding and attenuating until they’re lost in the quantum noise.

          1. That is how we are supposed to understand it, and your example is excellent. But the swirls of dust are a more complex pattern, and that pattern really looks like it is expanding without morphing to a different pattern, unlike the brain scan. At least it does to me.

            1. I wouldn’t take the NYT video too literally. I think much of what we’re seeing there is artists’ renderings of the explosions that created the clouds, not the actual light echoes reflecting off the existing clouds.

              Here is a video of the actual light echo. But note that even this video is based on just eight images; the rest of the frames are interpolated computer animation.

              This video seems to be the most realistic example I can find of actual light echoes, in this case around the variable star RS Puppis.

  4. Ashes to ashes, dust to dust applies even to stars, the universe is amazing. Back into the universe that gave you birth little star.

    Also the name is Overbye with only one Y.

      1. And looking back, I think many of us were very pre-occupied with the wars in the Arabian Peninsula. And here we are again, still kicking at that can…. sigh… the world can be such a sad and unfriendly place.

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