The Best Stars You Might Never See

> “The image is more than an idea. It is a vortex or cluster of fused ideas and is endowed with energy.” -Ezra Pound

Back in the 1800s, observational astronomy was already entering its heyday. We had already discovered Uranus, the first planet not visible to the naked eye, knew of a number of comets and asteroids, and had a whole catalog of “bizarre” objects in the sky.

Some turned out to be star clusters, globular clusters, remnants of exploded stars, or other galaxies entirely! But one of the unfortunate things about astronomy around 1800 is that the Southern Hemisphere objects were grossly under-represented. It wasn’t until 1834, when John Herschel (son of William Herschel, famed discoverer of Uranus) first laid eyes upon NGC 3603.

(Image credit: Chris Middleton.)

This object was so bright and dense, Herschel originally thought this was a globular cluster! You don’t have to look to hard to figure out why.

(Image credit: ESO.)

What’s a globular cluster? Have a look at Messier 3, shown below, which is an actual globular cluster, with hundreds of thousands of stars located within just a handful of light years of one another.

But the Hubble Space Telescope, as it so often does, told us so much more about this object. Let’s take a look at the first famous Hubble picture of NGC 3603.

Sure, it might look like a globular cluster, but it’s far more interesting than that. Notice how it’s surrounded by some sort of gaseous nebula? Globular clusters live mostly in isolation, far away from any other action. But this glowing gas shows us that there’s a lot going on near this cluster. This is a new star cluster, and it’s a part of our own galaxy, only 20,000 light years away!

But it isn’t just special because it’s new.

It’s also the densest star cluster ever discovered! In fact, recently we’ve been able to peek into the core of this star cluster, and the results are spectacular. Inside live some of the most massive stars ever discovered, including the two most massive ones ever directly measured.

(Image credit: Hubble Space Telescope, once again!)

Some of these stars are huge. Compared to our Sun, which is a G-type star in the diagram below, this collection of O-stars is amazing, including one with a mass of 116 times our Sun!

But when we get all the way down to it, our advanced telescopes with adaptive optics — particularly the VLT — can do even better than Hubble in some ways!

Take a look at what the Very Large Telescope discovered when they turned on their new adaptive optics system for the first time (at right, below).

The difference is amazing! Not only are there these big bright stars in there, but there are a whole slew of smaller, faint ones! The brightest objects often dominate, but thanks to new advances in imaging technology, we can learn that even in the brightest, densest star cluster ever discovered in the Universe forms the same faint, dim stars that we see in the darkest places!

Some of the most wonderful places in the Universe are right in our own backyard, but this is one for those of you with access to the Southern Skies; NGC 3603 is invisible to all of us in the U.S. and Europe!

For one last spectacular fact and image of it, it contains the densest collection ever discovered of bright, massive stars at its core. Want to see?

(Image credit: Max Planck Institute for Radio Astronomy.)

Simply amazing, that we can reconstruct the stars in the core from the images at left. And it’s totally conceivable, billions of years ago, that the Sun was born in a region just like this. Enjoy these gorgeous views of baby stars, and have a fantastic weekend! Read the comments on this post…


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