The Little Galaxy that Could

Galaxies make stars. That’s what they’ve done since, well, since just about forever–in the cosmic scheme of things. Colliding galaxies pump out stars in huge batches. The action of smashing together two galaxies usually compresses their clouds of gas together and when you compress enough hydrogen gas together, you get stars. In colliding galaxies you get massive starburst regions like the one in NGC 1569, seen here through several observations made by Hubble Space Telescope’s Wide-Field Planetary Camera 2 and the Advanced Camera for Surveys.

The core of the starburst galaxy NGC 1569. This region contains three giant star clusters grouped inside a huge central cavity hollowed out by winds from the formation of massive stars. Those stars are long gone, having exploded as supernovae. The outbursts from those explosions hurled a river of gas and dust that is sculpting the 3,700 light-year-long outflow structure at the lower right (in red). (Click to embiggen.)

Now, astronomers have long puzzled over a small, isolated nearby galaxy (about 11 million light-years away) because it is ablaze with starburst activity. There are millions of newly formed stellar babies here, and this galaxy is continuing to pump out newborns a hundred times faster than the starbirth regions in the Milky Way Galaxy. So, given the intense rate of starbirth, you’d think you’d there’d be a collision involved here.

But, no, this galaxy seems to be all by itself.

Or so astronomers thought.

When they reanalyzed the observational data, they found that it really lies about one and a half times farther away from us than they thought. And that makes a huge difference. It puts this galaxy in the middle of a group of ten other massive galaxies. Interactions between this group that may be the culprit in compressing the gases in NGC 1569 and pumping up its prodigious starbirth engines. That interaction also makes this one of the most active galaxies in our local neighborhood.

Wearing Ultraviolet Swim Goggles

It's Galaxies (nearly) All the Way Out! (Click to embiggen)

This is a region of space called the Chandra Deep Field-South, a region of the sky that fascinates astronomers so much that it is one of the best-studied in the whole sky. Over the past few years and into the future, astronomers have been and will be concentrating on this region and one other in the northern sky as part of the GOODS survey, to do the deepest, most sensitive observations they can with every observatory on the ground and in space, in every wavelength possible.

The European Southern Observatory’s Very Large Telescope took its turn, along with the 2.2-eter MPG/ESO telescope. Together they gazed for 55 hours, using the ultraviolet-sensitive VIMOS instrument on VLT and the Wide-field Imager on the MPG/ESO telescope at La Silla.

They announced the result today: a 27-million-pixel-wide image that shows a  pool of galaxies, many of them appearing as they were when the universe was only 2 billion years old.  These most distant galaxies are a billion times fainter than the unaided eye can see, and not easily visible to optical instruments. Ultraviolet-sensitive instruments like VIMOS (which focused on wavelengths of light in a range between UV and optical), when used in longer exposures, can catch enough of the light from these distant galaxies to reveal them for us to see.

Nearly everything you see in this image (with the exception of a few bright stars in the foreground (part of the Milky Way Galaxy) is a galaxy. Each of those galaxies has billions of stars.

Now, here’s a thought-provoking idea to chew over while you gaze at this picture:  the universe looks the same no matter what direction we look in — that is, it has a roughly similar distribution of structure (galaxies and clusters of galaxies) in all directions.  This means that if we could point telescopes in all directions of the sky (without interference from the Milky Way) the distant universe would look like this all over the sky. Think about it–countless millions or billions of galaxies… some dating back to the childhood of the cosmos!

And Sending Great Images Again!

Interacting galaxies Apr 147

To celebrate a triumphant comeback from the jaws of Side-A madness, Hubble Space Telescope folk pointed the observatory at a pair of interacting galaxies called Arp 147 that just sort of happen to form what looks  like the number “10″ (if you stretch your imagination a little.  This WFPC2 image shows that everything’s in working order and HST’s back to doing science.  Let’s hope it stays working well until the servicing mission can get there to do HST’s long-awaited cosmic makeover.

So, what’s happening in this picture?

The left-most galaxy, or the “one” in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The galaxy on the right is the “zero” in this 10. It’s a clumpy, blue ring crammed full of regions where intense star formation is taking place.

The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, the collision and “punch through” of one galaxy through another sent a density wave out from the point of impact. It collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies. The result?  More shocks and clumps of dense gas were produced. This spurred the star formation we see in the galaxy on the right. The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.

Side B Switched On

Earlier today (October 15), Hubble Space Telescope’s handlers completed switching systems over to the B-side, essentially working around the failure of the A side of the science instrument command and data handling computer that stopped working a couple of weeks ago.  At 6 p.m. (EDT) tonight the spacecraft began running a pre-science command load, where controllers send normal commands to control the spacecraft and resume communications satellite tracking with the telescope’s high-gain antennas.

Overlapping Galaxies 2MASX J00482185-2507365

People are working through the night to test the system. If all goes well, then HST could resume normal operations soon. The good news here is that — so far — things are looking good, especially when you consider that Side B has been sitting there waiting to be used for 18 years… and it seems to be working like a charm. Stay tuned!

And, to whet your appetite for more HST images, here’s a treat — an image of two spiral galaxies superimposed on each other as seen from our vantage point on Earth.

The background galaxy is about 780 million light-years away; the forground one is obviously closer, but they haven’t measured a distance to it yet.

These were imaged by HST’s Advanced Camera for Surveysd on September 19, 2006.  Lovely!

GO HST!!!

Hubble Captures Overlapping Galaxies

Two galaxies as one: 2MASX J00482185-2507365.

Keeping on the theme of galaxies today, Hubble Space Telescope just released this lovely image of two overlapping galaxies. Seeing such alignments like this is somewhat rare. Even though there are millions and millions of galaxies in the universe, they don’t always lie at overlapping angles from our point of view.

The large background galaxy is about 780 million light-years away and the smaller one in front of it is obviously a bit closer. Astronomers are not sure how far apart these galaxies are, but it doesn’t appear that they are interacting at the moment.

If you look closely at the smaller one, you can see dark dusty areas along the outer edges — they’re highlighted against the bright core region of the larger galaxy. This is also pretty rare to see dust this far out from the visible “edge.”

The stars you see all around these two galaxies are part of another galaxy called NGC 253, which is in the constellation Sculptor (in the southern hemisphere). So, we’re looking the edge of one galaxy to see two much more distant spirals.  Very, very cool!

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