Galaxy Details and Mergers

Astronomer Edwin Hubble pioneered the study of galaxies based simply on their appearance and categorized them according to three basic shapes: spiral, elliptical, and irregular. Some 60 years later, the sharp vision of the space telescope named in his honor began seeing unprecedented details in galaxies, revealing intricate, dark dust lanes and glowing knots of star formation. Hubble helped uncover the supermassive black holes that power the bright centers of massive galaxies, and revealed the interdependent relationship black holes have with their host galaxy.

Astronomers classify galaxy NGC 1300 as a barred spiral because its arms do not swirl into the center but instead are connected to ends of a straight bar of stars that contains the nucleus.

NASA, ESA and The Hubble Heritage Team (STScI/AURA); acknowledgment: P. Knezek (WIYN)

Hubble has also captured merging galaxies that look like a “Great Pumpkin,” a “Space Triangle,” “Antennae,” and “Mice.” For all their violence, galactic collisions take place at a snail’s pace – over timescales that span several hundred million years. Hubble captures a mere snapshot of these mergers.

Long streamers of stars and gas appear as tails in this Hubble image of the gravitationally interacting galaxies NGC 4676, nicknamed “The Mice.”

NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team and ESA

This computer simulation depicts the colliding galaxies that form “The Mice.”
Josh Barnes (University of Hawaii) and John Hibbard (National Radio Astronomy Observatory)

Hubble images of the “tadpole-like” Antennae and Mice galaxies reveal the gravitational turbulence these galaxies endure. The interacting duo called Arp 143 (the “Space Triangle”) holds a pair of distorted, star-forming spiral galaxies. Astronomers think the pair passed through each other, igniting a triangular firestorm of new stars.

Mergers like this preview the coming collision between our own Milky Way and the neighboring Andromeda galaxy 4 billion years from now.

Comma shaped curved cloud of gases in bright white edged with bright-pink star forming regions, and threaded with rusty-brown tendrils of dust at center and throughout the comma shaped merger. All set against the black of deep space.

Located some 65 million light-years away, the Antennae – also known as NGC 4038 and NGC 4039 – are locked in a deadly embrace. Both galaxies were once sedate spirals like the Milky Way, but the pair has spent the past few hundred million years sparring with each other. The clash is so violent that stars were ripped from their host galaxies to form a streaming arc between the two.

NASA, ESA

The “Antennae Galaxies,” NGC 4038 and 4039, are spiral galaxies in the process of merging. The bright knots in the bluish areas are massive pockets of young star clusters, whose formation was sparked by the turbulent interaction of the galaxies. Credit: NASA, ESA and G. Bacon (STScI)

Learn More

Super Star Clusters in the Antennae Galaxies
As these two galaxies collide, billions of stars formed. The brightest and most compact of these star-birth regions are called super star clusters.
Galaxy Collision Creates "Space Triangle" in new Hubble Image
A spectacular head-on collision between two galaxies fueled an unusual triangular-shaped star-birthing frenzy.
Sombrero Galaxy's Halo Suggest Turbulent Past
Hubble's sharpness and sensitivity resolved tens of thousands of individual stars in the Sombrero's vast, extended halo, the region beyond a galaxy's central portion, typically made of older stars.
Hubble Reveals Stellar Fireworks Accompanying Galaxy Collisions
Hubble uncovered over 1,000 bright, young star clusters bursting to life in a brief, intense, brilliant "fireworks show" at the heart of a pair of colliding galaxies.