[Update: I originally had called this the Very Large Survey Telescope, but have learned it's actually the VLT (for Very Large Telescope) Survey Telescope. I've corrected this in the title and below. I like my less-redundant name for it better, but it's best to be accurate.]

The European Southern Observatory is an agency that governs some of the best telescopes on the planet, and they just added a new eye on the sky: the VLTe Survey Telescope (VST), a 2.6 meter ‘scope in Chile. There are lots of telescopes of similar size dotting our planet, but what makes this one special is its huge field of view — a solid one degree across, twice the diameter of the Moon on the sky – and the resolution of the camera: a terrifying 268 megapixels!

When you put that together, you get some dazzling pictures, like this one of the globular cluster Omega Centauri:

[Click to englobulenate to a 4000 x 4000 pixel 13 MB image, or grab yourself the internet-choking 14,540 x 14,540 pixel 280 MB version.]

Omega Cen is one of the largest globular clusters of the 150 or so orbiting the Milky Way galaxy, a collection of hundreds of thousands or even millions of stars all orbiting the cluster center willy-nilly like bees swarming around a hive. Telescopes like the VST will allow astronomers to survey these clusters quickly and deeply, which is important because it’s sometimes difficult to know what stars are in the cluster and which happen to be in the background or foreground. You have to get a good census of cluster membership before moving on to studying how old the stars are, what they’re made of, and how they behave. Since globulars are among the oldest objects in the Universe and are tied with galaxy formation, understanding them leads to understanding a great deal more.

VST also took this spectacular picture of the star-forming region M17, also known as the Omega nebula:

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Globular clusters are among the most spectacular of objects in the entire night sky. Compact balls of hundreds of thousands of stars, well over a hundred orbit our galaxy at various distances. When viewed by Hubble, the result is nothing less than jaw-dropping:

[Click to embiggen, and please do; I had to crop the image to get it to fit and the full-size version is even more spectacular!]

This view of Terzan 5, as it’s called, is gorgeous! The thing is… Terzan 5 may not really be a globular cluster. Sure, it’s a cluster, and it’s globular, but it may not be what we usually think of as a globular cluster.

When I read the press release for the picture, the name Terzan 5 looked familiar. So I searched my blog, and found I’ve written about this object before. That post was about a ground-based Very Large Telescope picture of the cluster, seen here. The picture looks odd because Terzan 5 lies in a very crowded region of the Milky Way, lousy with dust. That interstellar junk tends to scatter away blue light, making objects look redder. The dust blankets across Terzan 5, but is thicker in one half than the other, making that side redder than the other.

Terzan 5 itself is also unusually dense, with stars packed in it more tightly than is usual for a globular cluster. Not only that, but studies have shown the stars in the cluster appear to fall into two different age groups; one significantly older than the other. That’s weird. (more…)

When I was a young Bad Astronomer, one of my favorite night-sky targets for my telescope was the globular cluster M5, an easy-to-spot fuzzy jewel in the southern sky. Over the years I must have taken a look at it a hundred times, my telescope barely resolving a few of the brighter stars in it.

Of course, with Hubble, the view is significantly better:

Holy scintillating jewelbox! [Click to englobenate, or grab the 3150 x 3150 pixel version.]

M5 is a collection of at least 100,000 stars, all orbiting each other like bees around a beehive, held together by their mutual gravity. It’s located about 25,000 light years away, and is something like 150 light years across. It’s one of more than 150 such clusters of stars orbiting our Milky Way galaxy.

And it’s old: it’s probably been around for 12 billion years. Yikes. I hope I look as good when I’m that relatively scaled age.

I don’t have much to add here; I’ve written about globulars many times (see Related Posts below), so instead I’ll simply let you soak in its beauty… and note that despite my best efforts, I couldn’t seem to work in an Ultimate Computer reference in this post’s title. You may pull out the plug, Mr. Spock!

Image credit: ESA/Hubble & NASA

I love all the Hubble images of nebulae and galaxies, but sometimes you need a palate cleanser, an image clean and simple. Like one, say, full of the stars of NGC 288:

[Click to englobularclusternate.]

NGC 288 is a globular cluster, which are usually tightly-packed spheres of stars. NGC 288, though, is looser, with stars dispersed more throughout. This image from Hubble actually resolves the stars even in the core, where they tend to overlap in denser clusters. From 30,000 light years away — half the diameter of our galaxy! — this is a pretty decent feat.

The image is not exactly true color: blue is blue, but orange starlight is shown as green here, red represents near infrared light, and what you see here as orange is actually from the reddish glow of hydrogen. Confused? Yeah, sometimes astronomers color things oddly to make some characteristics clearer. In this case, the colors represent different mass stars. Medium mass red giants look yellow in the picture, and blue stars are more massive. The fainter stars are ones that are still happily fusing hydrogen into helium like the Sun does. However, those stars are much lower mass than the Sun, and have longer life spans.

And there’s more: If you look carefully, you can see fuzzy orange objects poking through the stars. Those are distant background galaxies! They’re probably hundreds of millions of light years away.

We think most globular clusters like NGC 288 form their stars all at once, making them really nice laboratories for studying how stars grow old and die. Since we can be pretty sure the stars are all the same age, it’s one less thing we have to worry about when trying to understand them! Simplification can be nice… in science and in beauty.

When I was younger, it was pretty common on clear nights to see me at the end of my driveway with my telescope. And one of my favorite targets to observe was (and still are) globular clusters: hundreds of thousands, and sometimes millions of stars all bound together in a tight ball due to their gravity. And one of the best of those is the fabulous M15… and when it’s seen by Hubble, well, it’s simply spectacular:

Holy wow! Click to englobulenate – I had to shrink the image a lot to get it to fit here, so as gorgeous as this is it’s a shadow of the higher-res version… or the ginormous full-res one!

M15 is relatively nearby as globulars go, about 35,000 light years. Over 150 of these objects orbit our galaxy, and so some are quite far away. Not only is it close, but M15 is also fairly densely-populated, its stars orbiting each other like bees around a beehive, making it a pretty easy target for amateur astronomers. It was one of the first things I’d go after once it got dark in the autumn, and it would appear as a fuzzy ball in my 25 cm ‘scope. Of course, when you aim the 2.4 meter mirror of Hubble at it, well. You can see for yourself.

This false-color image is a combination of two pictures; one taken in visible light (colored blue; in reality the filter used let through yellow and red light), and the other in near-infrared (colored red). That selects out redder stars; the brightest ones are red giants, stars nearing the ends of their lives, and the fainter ones are lower-mass stars that are still busily fusing hydrogen into helium in their cores.

If you look to the left and a bit below the cluster’s center, though, a blue glow sticks out among all the red. If you do grab the seriously super high-res version of the image, you get a much better look at it. I’ve zoomed in on it here. It’s clearly not a star; the blue halo is much larger than any star image, and you can see the rim on the left hand side is bright. What gives?
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Use the thumbnails and arrows to browse the images, and click on the images themselves to go through to blog posts with more details and descriptions.

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Globular clusters have always been one of my favorite astronomical objects. These balls of stars — sometimes hundreds of thousands strong — are easy targets through a small telescope and are fun and beautiful to see.

But when you train a big space telescope on them, well, their beauty is magnified spectacularly:

You really want to click that to get the very beefy 4000 x 4000 pixel (11 Mb) version. It’ll knock your socks off!

This Hubble image shows NGC 6934, an ancient ball of stars located about 50,000 light years away. Globular clusters are made of stars that are bound to each other gravitationally and orbiting the center on a myriad different paths — think of it as a beehive except with a hundred thousand bees each a million kilometers across. There are about 150 of these guys orbiting the Milky Way, each a dozen or so light years across and containing upwards of a million stars. NGC 6934 is pretty typical of its class, but its great distance dims it to near-obscurity. If it were as close as M 13 or Omega Centauri — both roughly half as far as NGC 6934 — it would be heralded as a gem of the night sky.

Globulars are old. We think they form all at once, with all the stars being born at the same time. (more…)