Blogs / Bad Astronomy

The Local Group of galaxies is our Milky Way’s neighborhood: a few dozen galaxies dominated by our own, as well as Andromeda and a handful of largish ones.

But by far the majority of galaxies in our group — the majority everywhere, really — are dwarfs; small collections of stars and gas with only a few million stars. Lurking just 1.6 million light years away, half the distance to Andromeda, is Barnard’s galaxy, an irregular dwarf with about 10 million stars. Behold!

[As usual, click to embiggen, or get a ginormous 80 Mb TIF.]

This is perhaps the finest near-true color image of Barnard’s galaxy I have ever seen, courtesy of the European Southern Observatory’s 2.2 meter telescope in Chile… a far cry from the small 12.5 cm (5 inch) refractor Barnard himself used to discover it. Given that this diminutive galaxy is in the direction of Sagittarius — toward the center of our galaxy, which is loaded with stars — it’s incredible Barnard found it at all. In fact, most of the stars in this image are inside the Milky Way, between us and the other galaxy.

Barnard’s Galaxy is not precisely irregular, since it appears to have a bar-like structure across it. The red bubbles are regions where stars are being born in large numbers; the UV and fierce winds of subatomic particles from the massive stars being formed carve out cavities in the gas, creating what look like smoke rings. The red glow is characteristic of hot hydrogen, and is a sure-fire way to know that gas is being excited by the stars nearby. The sharp edges to the bubbles are real, due to the gas piling up as it rams gas in interstellar space in a cosmic snowplow effect. There are over 150 separate bubbles like these in the galaxy, some of which have been observed using the Hubble Space Telescope.

There is another feature here that’s not obvious. On the left and right of the galaxy are faint, thick, blue arcs. This is actually gas that’s being blown out by the stars in the center of the galaxy, forming a weak ring surrounding the entire structure. I expect that gas will blow right out of the galaxy entirely; the gravity from the meager number of stars making up Barnard’s Galaxy can’t possibly be enough to restrain it.

Dwarf galaxies are difficult to observe because they are so faint; they fade with distance rapidly, so only nearby ones can be studied in detail. But since they are the most numerous types of galaxy in the Universe, these tiny smudges are well worth studying, and images like this one of Barnard’s Galaxy will help us understand how these galaxies formed, and what they’re made of, and how they behave. We also think that through collisions, these galaxies can grow to become larger, more magnificent ones like our Milky Way, so, as usual, when we study the Universe, looking ever outward, we are actually turning our gaze inwards to learn more about ourselves.

Image credit: ESO.

I have been behind in my cool-astronomy-posting, and haven’t mentioned the GigaGalaxy Zoom project, an ambitious and totally awesome three-part image series by the European Southern Observatory. The first part was to create a magnificent all-sky view of the heavens; the second was a zoom in on the Milky Way showing a region choked with stars and dust.

The third is of the Lagoon Nebula, a star forming region a quadrillion miles across and 400 light years in toward the center of the galaxy. And the image? Well, if you want the full-res version, you’d better have some room on your drive: it has 370 million pixels and will eat up a whopping 700 Mb of disk space.

And what does it look like? Heh heh heh. Like this:

[You know the drill, click to embiggen. Do it! Now!]

Oh. Wow. And that’s low-res! Here’s the monster one if you want it.

The depth and detail are simply and truly jaw-dropping. You can zoom in and see young stars, massive stars, dark clouds, ribbons and sheets of gas sculpted by vast winds of subatomic particles blown off of supergiant stars.

The Lagoon was always a favorite target of mine in the summer months when the center of the Milky Way in Scorpius and Sagittarius would just clear my neighbor’s trees. A nearby streetlight always made observing in that direction a pain, but even from a distance of 40 quadrillion kilometers away the nebulous glow of gas and newly-born stars still shone through. I wouldn’t have been able to imagine back then that I’d be able to zoom in on the Lagoon using a 2.2 meter telescope equipped with a 67 megapixel camera!

There is science in this picture, to be sure. We can study it to look at the shape of the nebula, how it interacts with the stars and other nearby nebulae, and much more. But you know what? At this exact moment, I don’t care.

Because my oh my, the Universe is a beautiful place. And sometimes, for just a little while, that’s enough.