A Sky Full of Galaxies, and What Else?
The farther out from Earth you look into space, the more galaxies you see. As you let your eyes roam around this recently released Hubble Space Telescope image, notice how many galaxies you see. Not sure what’s a galaxy? Look for things that are kind of cigar-shaped, or with spiral shapes. Some galaxies in this image may look blobby or irregular. There are hundreds of them in this image.
The objects with crosshairs on them? Those are stars that lie fairly close to us. The blue cloud of light off to the bottom left? That’s why this picture was taken. It’s a portion of a galaxy called that is being disrupted by an encounter with another galaxy. The two together are called NGC 4038 and NGC 4039, and nicknamed the Antennae. They lie about 45 million light-years away from us (and all those other galaxies lie at least that far away, or more). As they merge together, the gravitational influences of the two are warping them, and sending out two tails of gas. The blue color comes from the new stars that are being born under the influence of this galactic commingling. Star formation is a major “effect” of galaxy collisions, and contributes to the long-term evolution of galaxies and the stars they contain.
(Images Credit:NASA, ESA & Ivo Saviane (European Southern Observatory)/Robert Gendler)
Hubble Space Telescope has been peering out at galaxies (and all kinds of other objects in the cosmos) since 1990. Over the years it has captured many views of galaxies interacting. By interacting, I mean that they come together, they collide, they mingle stars and clouds of gas and dust, and then in the aftermath, new stars are formed. The view from a distance is breathtaking. Like this one. The combined galaxy interaction is named NGC 5331, and they lie about 450 million light-years away from us in the direction of the constellation Virgo.
To celebrate the 18th anniversary of Hubble’s launch (gad, has it been 18 years already?), the Space Telescope Science Institute and the Hubble ESA folks have released an image collection of 59 galaxy interactions. Here’s another one — the interacting galaxy pair that makes up Arp 148. This one shows the pair well after the collision (interaction) began. The blue “ring-shaped” object is a collection of matter ejected by the shockwave generated during the collision. It’s blue because the shock also touched off a burst of star formation. Those are hot, young blue stars there, just beginning their lives in the chaos of a galaxy collision.