Check this image out:
It’s an infrared view of stars embedded in a cocoon of gas and dust. To an optical telescope there wouldn’t be much to see there; the dust blocks visible light. But this image was taken in the infrared (at 3 microns, more than three times the wavelength the human eye can see) using a new camera on the Very Large Telescope in Chile. The camera, called HAWK-I (High Acuity, Wide field K-band Imaging) is pretty impressive. It is very sensitive to infrared light, has incredible resolution (0.1 arcseconds per pixel, which is basically what Hubble can do) and a wide field, peering at a field 7.5 arcminutes square. That means it’s looking at an area on the sky about 1/12th the size of the Moon on the sky.
For astronomers, that’s a big bite o’ sky.
Better yet, it’s sitting on the business end of the VLT, which sports a whopping 8 meter mirror (for comparison again, Hubble’s mirror is 2.4 meters across, less than 1/10th the area). That means it can spot very faint objects. This is an astronomer’s goal: faint objects are almost always really interesting; they are either intrinsically faint, like dim stars, which tells us about how stars behave at the low end of the mass scale; they are embedded in dust and hard to see otherwise; or they are really, really far away.
Very distant galaxies, for example, can have their light redshifted into the infrared because they are receding from us. Optical images won’t tell you much necessarily, but HAWK-I will get a good view of them, seeing both small and faint details. This is pretty important if you’re trying to compare distant galaxies — which we see when the Universe was young — with closer, older galaxies.
The image above is pretty interesting, but the press release is vague on details (this happens frequently with ESO press releases). I am particularly interested in the ring of material that appears to be around the bright central star. Is that a hole carved out by stellar winds from a young star? Sure looks like it; the bright rim would be where the wind from the star (actually it looks like a binary) is slamming into the dusty material around it, warming it up. The fainter star directly to its left has an arc of red dots around it. What are those?
Even cooler, look at the whitish star above the bright one. There are two cone-shaped dark regions going out from it in opposite directions. I just bet that star has a thick disk of material around it, and the light from the star is blocked by that disk. The starlight illuminates the dust above and below the disk, but in the disk’s plane you see the light shadowed. I’m just guessing… but I bet I’m right.
Until the James Webb Space Telescope comes along (when? 2013? later?), HAWK-I is our best IR eye on the sky. I’m looking forward to seeing lots of cool images and science from it! And hopefully, some more about the way kewl image above.
August 24th, 2007 at 1:38 pm
How do they get down to 0.1 arc sec? That’s pretty good seeing for a ground based system. I guess I’ll have to check the VLT’s specs.
August 24th, 2007 at 1:49 pm
That’s not the seeing, it’s the pixel size. They have claimed 0.34 arcsec seeing. VLT has adaptive optics, too.
August 24th, 2007 at 2:10 pm
Awesome picture. I like that big, bright red star in the upper left. It reminds me of Amsterdam.
August 24th, 2007 at 2:13 pm
How will Hawk-1 complement/compare to the upgraded Hubble in their ability to peer into the early universe?
August 24th, 2007 at 2:32 pm
Does anybody else think that that star in the center looks like an eye? Well, “eye” think this picture is pretty hot!
August 24th, 2007 at 2:58 pm
Okay, so the whole thing is a few arcminutes across. But, how far away is this? We need that to get a sense of scale. For example, what is the diameter of the “hole” around the center star? What is the diameter of those red dots around the star to its left?
August 24th, 2007 at 3:18 pm
Here’s something that never occurred to me. You say that objects that are receding from us can move into the infra-red due to red shift. Is it possible for objects that are ultra-violet (that is, off the other end of the visible spectrum from infra-red) to become visible due to red shift?
August 24th, 2007 at 5:29 pm
Those really are impressive capabilities. Infrared should be pretty exciting because the most dynamic regions where most of the new stars are being formed are surrounded by gas&dust, and the later absorbs the visible light. Also as bad points out, the low end of the stellar mass scale, near brown dwarfs is not very well known. I for one would like to know the mass spectrum of starts, (i.e. how many of a given mass), how does it behave at the low mass end of the spectrum?
August 24th, 2007 at 8:43 pm
Darrin asked:
Is it possible for objects that are ultra-violet (that is, off the other end of the visible spectrum from infra-red) to become visible due to red shift?
Certainly, although in those cases it would be called “blue-shifting.” An object would have to be moving pretty fast relative to us get shifted significantly toward ultraviolet, so much so that any object within the Milky Way would be moving faster than galactic escape velocity and thus probably not blue-shifted towards us for very long.
On a more mundane scale: because the Andromeda and the Milky Way galaxies are falling toward each other, each is blue-shifted from the other’s point of view. Our mutual blue-shift is not great: about 300 Km/sec, or about 0.1% the speed of light. Compare this to the redshift of the quasar 3C 273 (the first one discovered): over 47,000 Km/sec, or just under 16% the speed of light.
August 24th, 2007 at 8:56 pm
Great picture.
I like the soft glow of the stars within it.
Must be kind of strange to look from a planet in this nebula and seeing nothing but reflections of low light on the sky.
Yours Sincerely.
August 24th, 2007 at 9:16 pm
Arthur, you’re close, but not quite.
Imagine a galaxy a long ways off. It emits some ultraviolet, say at 2000 Angstroms. If it is far enough away, it’ll be receding such that the light is red shifted to, say 6000 Angstroms (roughly in the orange part of the visible spectrum).
This is actually pretty useful info. If you take a spectrum of a galaxy, you are looking at the combined light from all the stars. In most cases, you can tell what kind of galaxy it is just by glancing at such a spectrum. For many stars, there is a sudden cutoff of emitted light by color in the UV. A spectrum of such a galaxy has a steep decline in light in wavelengths shorter than that. If you take an series of images with filters, you see the galaxy get much fainter when you use a blue enough filter!
If the galaxy is redshifted, that cutoff moves from the UV into the visible. By examining the images, you can actually estimate the redshift using images without taking a spectrum. This is a pretty sophisticated method these days, and works quite well.
August 25th, 2007 at 12:12 am
[...] times the wavelength the human eye can see) using a new camera on the Very Large Telescope in Chile.read more | digg story Bookmark [...]
August 25th, 2007 at 12:26 am
ESO press releases almost deserve their own frustrated blog post…
August 25th, 2007 at 12:44 am
Luna’s comment got me thinking… I’ll bet that if you were observing from a point inside a nebula, specifically a planetary nebula, that you wouldn’t be able to see it very well. It seems to me that most of the diffuse objects like that are seen from our point of view only because we are looking through areas that have a lot of stuff (gas, dust, etc) in them *from our angle of view*. But if you are *inside* the nebula, you are deprived of that, and every direction has an equally wispy amount of stuff, so it would be much harder to see.
August 25th, 2007 at 10:54 am
HAWK-I is installed on UT4 (There are 4 Unitary Telescopes in the VLT), which happens to be the only one that has, in addition to an Adaptive Optics module, a Laser Guide Star.
August 25th, 2007 at 11:22 am
Thanks, BA! I was just using my modicum of college-level freshman physics–which did not get to the point of discussing the UV cutoff (dealing only with theoretical blackbody radiation)–and mainstream astronomy news. It’s always a successful day when I can say that I learned that something I thought I knew wasn’t quite right.
August 25th, 2007 at 11:25 am
Astrogeek, that’s true. The light from the nebula is spread out over the whole sky, so the light per square degree is very small. This was the topic of my very first ever paid magazine article in Astronomy mag in 1998.
August 25th, 2007 at 5:11 pm
What about the south pole telescope? How is it compared to Hawk-I? It has a 10 meter reflector. But I think it’s sensitive to longer wavelengths? If so, can it take pictures of the same cloud and give useful information?
August 25th, 2007 at 9:03 pm
The South Pole Telescope views at wavelengths of a few millimeters, about a million times the wavelength at which this picture was taken(comparing the 3 microns cited above with 3 mm, cited as a typical wavelength on the SPT web site).
August 26th, 2007 at 3:26 am
Brian said:
“The South Pole Telescope views at wavelengths of a few millimeters, about a million times the wavelength at which this picture was taken(comparing the 3 microns cited above with 3 mm, cited as a typical wavelength on the SPT web site).”
[stage-whisper]Psst, Brian, that’s a thousandfold difference, not a million.[/stage-whisper]
BA, that’s another very fine image you’ve brought to our attantion. Thank you.
August 26th, 2007 at 8:14 am
oops.
August 26th, 2007 at 5:25 pm
In the lower part of the cloud there seems to be thin black lines running across. Any idea what could be causing it?
August 27th, 2007 at 7:51 am
Hi Phil,
Thanks for the great image. I have started a forum over at webbtelescopepictures.com/forum to try to build a community of people interested in the Webb Telescope program. Feel free to stop by and leave a few comments. I’m also compiling JWST news and photos at webbtelescopepictures.com/news.
I’m not trying to spam your comments, I just thought you and your readers might be interested. Thanks!
Andrew
October 27th, 2010 at 10:49 am
There may be nothing new under the sun, but the night time sky is clearly another matter. This is just awesome!