A Star of Space and Film

Rollie Hawk writes "Three years ago, light from V838 Monocerotis (a star about 20,000 light years from us) reached the Earth that showed the star exploding. The more politically correct term for what happened is "stellar outburst." In the time since, images from a pulse of light released during the outburst have been arriving here on Earth. In October of 2004, Hubble captured a beautiful image of the scene with the pulse lighting up interstellar gasses that encapsulated the area around this red giant (a star 600,000 times brighter than our Sun). The release of this photo just days ago seems rather timely, as it appears that some of Hubble's funding may be cut in the near future. There is also talk of eliminating the program entirely."

Comments

Astronomy picture of the day

[Cyrgo]

Here is NASA's Astronomy picture of the day site Astronomy picture of the day with the same picture and a brief explanation (with hyperlinks).
Enjoy

Re:High resolution image anyone?

[Cyrgo]

Try NASA's Astronomy picture of the day site and then click on the image to download a high res pic.
Enjoy!

Look at the entire series of HST images over time

[StupendousMan]

If you go to the HST web site, you can see an entire series of images of V838 Mon over the past three years.

http://hubblesite.org/newscenter/newsdesk/archiv e/ releases/2005/02/image/a

Although the series _appears_ to show a shell of gas expanding outwards from the star, it does not. Instead, what we see is the expanding echo of light reflecting off gas and dust in the interstellar medium, between V838 Mon and the Earth. It might help to look at a nice diagram of the "light echo" effect provided by space.com:

http://www.space.com/php/multimedia/imagedisplay /i mg_display.php?pic=light_echo_graphic_030326_02,0. jpg

The European Space Agency also has a good description of the event:

http://www.space.com/scienceastronomy/light_echo _0 30326.html

The fact that no material is actually shooting outwards into space as fast as the pictures appear to indicate -- that we are simply seeing a reflection of light as it moves through the gas cloud, like the beam of a flashlight swept through the air in a dusty room -- explains how the shell can _appear_ to expand outwards faster than light.

Apparently faster-than-light

[benhocking]

What's interesting, at least when you first think about it, is how the sphere of influence spans 14 light-years less than 3 years after we detected its "flash".

Of course, it's not really going faster-than-light, it's just a matter of perespective. The event happened 20,000 years ago, and the portion of the 14 ly radius sphere that's approximately 11 ly closer to us than the star should now be visible. That is, it took ~20,000 years for the flash to reach us, and ~(20,000+14-11) = ~(20,000+3) years for that portion of the echo to reach us.

Re:Look at the entire series of HST images over ti

[SpongeBobLinuxPants]

If you go to the HST web site, you can see an entire series of images of V838 Mon over the past three years.

Here's the link without the type-o :)

http://hubblesite.org/newscenter/newsdesk/archive/ releases/2005/02/image/a

Star Tomography

[Nuffsaid]

A very interesting thing about this stellar outburst is the possibility to get a 3D image of the cloud surrounding the star. Images of this event taken months apart (like this sequence) show the flash of light as it expands, illuminating regions of space that form spherical shells around the star. This gives a unique insight into the actual threedimensional structure of the cloud, a bit like a CAT scan builds a 3D view from a sequence of planar 2D images. Pity we don't have (for all I know) one picture per day: it would have made a stunning movie! No to mention the scientific value...

Re:Question for you astronomers out there....

[Have Blue]

It's not really *that* detailed- each pixel is at the very least a few hundred thousand kilometers across. And it's so sharp because the light is traveling through space, so there's nothing to blur the image or attenuate its intensity (besides the inverse-square law).

Re:Exploding stars

[argStyopa]

http://imagine.gsfc.nasa.gov/docs/ask_astro/answer s/980521a.html

The Question
(Submitted May 21, 1998)

Is there a possibility that a nearby star could go supernova and destroy the earth? Or have other bad effects on us?

The Answer
To destroy the Earth itself, the Sun will have to go supernova (which it never will).

If you are talking about the life on Earth, then there is a detailed calculation of the risks due to a nearby supernova on the web:

http://stupendous.rit.edu/richmond/answers/snris ks .txt

The author concludes that a supernova has to be within 10 parsecs (30 light years) or so to be dangerous to life on Earth. This is because the atmosphere shields us from most dangerous radiations. Astronauts in orbit may be in danger if a supernova is within 1000 parsecs or so.

No stars currently within 20 parsecs will go supernova within the next few million years.

There are some indirect effects, though, which are harder to evaluate: the possible effects on the Earth ozone layer is listed in the article above. Additionally, according to one calculation, the neutrino flux from a nearby supernova might heat up the Sun.

Best wishes,

Koji Mukai & Eric Christian
for Ask a High-Energy Astronomer

Re:Question for you astronomers out there....

[dr_canak]

As a very *amateur* backyard astronomer,

I think there is nothing wrong with the question. You actually get this kind of reaction almost all the time when people peer through a telescope for the first time expecting to see the types of images that appear on telescope boxes, in books, and in the media. Fabulous images of space that look nothing like that to the naked eye. People then get very skeptical (out of dissapointment) that space isn't like they thought it was gonna be. Obviously, looking through a telescope in your backyard shows nothing like what we see in pictures like the one referenced in this article.

With that said, the technology available in light gathering (in terms of sensitivity, especially in space where there is a lot less matter to block light) and the ability to apply filters to so many different wavelengths can really enhance interstellar phenomena. And actually, even the technology available to the amateur is nothing short of amazing. Just take a look the back of Sky and Telescope or Astronomy magazine to see amateur astrophotography.

I guess the important thing to keep in mind is that these pictures are enhanced. It doesn't mean the phenomena doesn't exist. Light is shooting out from the star, and it is passing clouds of interstellar medium that reflect that light, at all different wavelengths. People then just spend a ton of time, money, and computing power to enhance those images so that people can appreciate what goes on in our own backyard.

In the end, i guess you do have to trust that the base data itself is not "manufactured" by the government, but the data is certainly enhanced once its collected.

jeff

Re:Exploding stars

[mazarin5]

Actually, it's 1/r^2, and even with that degeneracy factor, a supernova would be powerful enough to vaporize objects as far as the Oort cloud.

It's a matter of perspective

[benhocking]

The event happened 20,000 years ago, and the portion of the 14 ly radius sphere that's approximately 11 ly closer to us than the star should now be visible. That is, it took ~20,000 years for the flash to reach us, and ~(20,000+14-11) = ~(20,000+3) years for that portion of the echo to reach us.

I hope that I didn't over- or under-simplify this. :)

Re:Budgets

[disserto]

While I agree with you that space exploration should get more funding, the $100billion+ that he wants for war doesn't go to car bombs. It goes to prevent them.

If you want fewer pictures of grisly car bombs, something has to be done about the car bombers. And it's not us.

But this is a completely different topic. Where's the pretty space pictures?!

I chose 11 to counter-act the 3

[benhocking]

And the 3 came from 2005-2002 (after re-reading the site, I should have chosen 2 (and hence 12 instead of 11) since the picture comes from 2004, but that doesn't change the explanation).

Imagine this: I'm blind and deaf, so the only way I can get communication from you is when you throw me a braille ball. Now, I know that all braille balls travel at 1 m/s, and I (somehow) know that you're 20,000 meters away (you're a really strong thrower), so when I catch your ball I know that you threw it 20,000 seconds ago. Now, there's a wall 14 meters from you that you simultaneously throw a second ball towards, and amazingly it reaches me after only 20,002 seconds! Well, since I know that it took 14 seconds for that ball to reach the wall, I subtract 14 from 20,002 to get 19,988. I now conclude that the wall is only 19,988 meters from me (i.e., it's 12 meters closer to me than you are), without needing to conclude that the ball has broken its "law" of traveling at 1 m/s.

I hope that helps.

Re:Why such extreme lens flare in Hubble images?

[mfago]

IIRC, the "flare" is diffraction from the secondary mirror supports, with the "shape" determined by the shape of the support (I think a cross in this case). A very long exposure makes it more obvious.

It's been a long time since optics, and not long enough since coffee.

Re:Image Flare? Is this real?

[Betelgeuse]

These are the so-called "diffraction spikes." They come from the light of bright stars diffracting around the telescope's spider. The spider is the system of supports that holds the secondary mirror in place.

Sometimes you do see bleeding from saturated stars, but diffraction around the spider is usually the explanation.