Category Archives: galaxy interactions

100 Hours of Astronomy, galaxies, galaxy interactions, hubble space telescope, international year of astronomy

Arp Goodness!

Leave a comment

More Great Views during 100 Hours of Astronomy

Remember that contest to select HST’s next imaging target?  Well, the image has been taken and posted to celebrate 100 Hours of Astronomy and IYA.  HST imaged the winner — Arp 274, set of galaxies jsut beginning to interact with each other.  HST’s view, which was taken on April 1-2 (just the last two days!) is here. It’s a stunner!

Arp 274 in all its glory -- as seen by HST. (Click to embiggen.)
Arp 274 in all its glory, as seen by HST. This is a set of galaxies about to begin interacting. They're blooming with star-formation sites. When galaxies interact and merge, the actions often spur gas clouds to form new stars in huge "star bursts". (Click to embiggen.)

Arp 274, also known as NGC 5679, is really a system of three galaxies. They’re probably at different distances from us and each other, but from our point of view here on Earth, they appear to be overlapping.  You can make out spiral shapes in two of the galaxies, although upon closer examination, there’s some distortion going on due to the merger activity. As we might expect from galaxies that are undergoing (or have undergone) a merger, there’s a lot of star formation going on. It’s triggered by the interaction of the galaxies as shock waves slam star-forming regions and jump-starting the stellar birth process. The starbirth regions are strong along the arms of the spirals and in the small blobby-looking galaxy to the left. .

The largest component is located in the middle of the three. It appears as a spiral galaxy, which may be barred. The entire system resides at about 400 million light-years away from Earth in the constellation Virgo.

Astronomers used Hubble’s Wide Field Planetary Camera 2 to image this striking galaxy triplet. Blue, visible, and infrared filters were combined with a filter that isolates hydrogen emission. The colors in this image reflect the intrinsic color of the different stellar populations that make up the galaxies. Yellowish older stars can be seen in the central bulge of each galaxy. A bright central cluster of stars pinpoint each nucleus. Younger blue stars trace the spiral arms, along with pinkish nebulae that are illuminated by new star formation. Interstellar dust is silhouetted against the starry population. The pair of foreground stars at the far righth are inside our own Milky Way Galaxy.

astronomy, evolution of galaxies, galaxies, galaxy interactions, galaxy shapes

View from a Distance

2 Comments

Galaxy Beauty

What if you could move anywhere in the cosmos just to get a good view? Where would you go? The view from our own planet takes in the interior of our own galaxy, plus a healthy look out to intergalactic space. We can see, literally, for billions of  light-years, provided we use the right instruments.  But, what if you could live on a world at the rim of a distant galaxy that was overlooking a pair of interacting galaxies?  What you like this to be your view?

NGC 1532/1 as seen by ESOs 1.5-meter Danish Telescope. (Click to embiggen.)
NGC 1532/1 as seen by ESO's 1.5-meter Danish Telescope. (Click to embiggen.)

This is a pair of galaxies called NGC 1531/2 and they lie about 70 million light-years away from Earth. From this point of view, we can tell they are interacting in a sort of spirited galactic waltz. The spiral galaxy in the foreground is being warped by its dance with the smaller galaxy just above it. The cosmic dance leads to another dramatic effect: a whole new generation of massive stars that were created in the chaos of collision during the dance.  They are visible as the purple objects in the spiral arms.

This view from your living room window on that distant planet I mentioned above is really an exquisite image from the European Southern Observatory. It was made by R. Gendler and J.-E. Ovaldsen who used the 1.5-meter Danish telescope to capture the image.

I often wish we had dramatic views like this from our own back yards here on Earth rather than the skies we do have. On the other hand, using telescopes like the ones at ESO, we really kinda do.  So, enjoy!!