Category Archives: galaxies

galaxies, galaxy interactions, starbirth

Star Pump

Leave a comment

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.

Starburst galaxy NGC 1569. Whats causing its starburst activity?
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.

astronomy news, galaxies, GOODs survey

Diving into the Galaxy Pool

3 Comments

Wearing Ultraviolet Swim Goggles

Its Galaxies (almost) All the Way Out!
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!