Hubble images a pair of tiny dwarf galaxies

By Georgina Torbet August 3, 2024

hubble dwarf galaxy pair ic3430 potw2431a 1 — ESA/Hubble & NASA, M. Sun

A new image from the Hubble Space Telescope shows a small dwarf galaxy called IC 3430 that’s located 45 million light-years away. This galaxy is classified as both a dwarf galaxy, because of its small size, and an elliptical galaxy, because of its form.

Elliptical galaxies are smooth and featureless, appearing blob-like and diffuse, unlike spiral galaxies, like our Milky Way, which have a distinct structure of a central hub and stretching spiral arms.

In this image, you can see the smooth oval shape of IC 3430. Elliptical galaxies are primarily composed of older stars, as they lack the gas required to form new stars, but in this case, you can see a core of hot blue stars in the center of the galaxy. These hot stars are younger, which is a rarity for elliptical galaxies.

This NASA/ESA Hubble Space Telescope image captures the dwarf irregular galaxy NGC 5238. — This NASA/ESA Hubble Space Telescope image captures the dwarf irregular galaxy NGC 5238. ESA/Hubble & NASA, F. Annibali

This other recent Hubble image also shows a dwarf galaxy, one called NGC 5238. This one is located 14.5 million light-years away, but has a different and more complex type of structure. It has glowing spots of brighter areas, which are groups of stars called globular clusters.

The structure of this galaxy gives clues to its history. Astronomers think that the structure comes from a historical merger, when another galaxy wandered too close to this galaxy and the two merged into one. This caused pockets of stars to form due to gravitational disturbances pushing and pulling at the gas.

Indications of a historical merger include groups of stars within a galaxy with different chemical properties, suggesting they formed in a different environment from their neighbors. By studying smaller galaxies like this one, astronomers can build up their understanding of how galaxies form and merge.

“One main theory of galaxy evolution is that galaxies formed ‘bottom-up’ in a hierarchical fashion: star clusters and small galaxies were the first to form out of gas and dark matter,” Hubble scientists explain in a press release accompanying this image. “Over time, gravity gradually assembled these smaller objects into galaxy clusters and superclusters, which explains the shape of the largest structures we see in the universe today.”

Topics

Tech News

Georgina Torbet

Space Writer

Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…

Space

Citizen scientists spot mysterious object shooting out of the galaxy at 1 million mph

This artist's concept shows a hypothetical white dwarf, left, that has exploded as a supernova. The object at right is CWISE J1249, a star or brown dwarf ejected from this system as a result of the explosion. This scenario is one explanation for where CWISE J1249 came from.

Citizen scientists have helped to identify an incredibly fast-moving object in space, which is traveling at such a speed that it will shoot out of the Milky Way and head out into intergalactic space.

Amateur astronomers working on the Backyard Worlds: Planet 9 project spotted the object, which was also observed by the recently-retired NASA NEOWISE telescope. The trio of citizen scientists -- Martin Kabatnik, Thomas P. Bickle, and Dan Caselden -- spotted the object named CWISE J124909.08+362116.0 several years ago, and now it has been confirmed they are co-authors on a paper about its discovery.

Space

James Webb Telescope captures gorgeous galaxy with a hungry monster at its heart

Featured in this new image from the NASA/ESA/CSA James Webb Space Telescope is Messier 106, also known as NGC 4258. This is a nearby spiral galaxy that resides roughly 23 million light-years away in the constellation Canes Venatici, practically a neighbour by cosmic standards. Messier 106 is one of the brightest and nearest spiral galaxies to our own and two supernovae have been observed in this galaxy in 1981 and 2014.

A new image from the James Webb Space Telescope shows off a nearby galaxy called Messier 106 -- a spiral galaxy that is particularly bright. At just 23 million light-years away (that's relatively close by galactic standards), this galaxy is of particular interest to astronomers due to its bustling central region, called an active galactic nucleus.

The high level of activity in this central region is thought to be due to the monster that lurks at the galaxy's heart. Like most galaxies including our own, Messier 106 has an enormous black hole called a supermassive black hole at its center. However, the supermassive black hole in Messier 106 is particularly active, gobbling up material like dust and gas from the surrounding area. In fact, this black hole eats so much matter that as it spins, it warps the disk of gas around it, which creates streamers of gas flying out from this central region.

Space

Gaia data shows hundreds of tiny moons orbiting around asteroids

gaia asteroid binaries mapping the stars of milky way pillars 1

There are plenty of moons orbiting around the planets in our solar system -- Saturn, for example, has well over 100 known moons -- and astronomers believe that planets outside our solar system almost certainly have moons too, called exomoons. Those are particularly hard to spot, but now researchers have a new bevy of a different type of moon to explore: those that orbit around asteroids.

It seems funny to think of it, but it's actually quite common for asteroids to have tiny moons of their own. These form what is called a binary asteroid, like the famous pair of Didymos and Dimorphos, which NASA crashed a spacecraft into in 2022. The new data about binary asteroids comes from the European Space Agency's Gaia mission, a space-based telescope that has spotted new potential moons around 350 asteroids.