Skip to main content
  1. Home
  2. Space
  3. News

Hubble revisits a funky irregular dwarf galaxy

Georgina Torbet
By

The majority of the thousands of galaxies we’ve discovered out in the universe fit into relatively well-defined categories: spiral galaxies like our Milky Way, elliptical galaxies which are long and thin, and lenticular galaxies which are somewhat halfway between the two. But some galaxies are oddities that don’t fit in these clear shapes, and those are called irregular galaxies. These galaxies can be chaotic and nonsymmetrical and can be formed by gravitational forces pulling regular galaxies into strange shapes.

This week’s image from the Hubble Space Telescope shows one such irregular galaxy called NGC 1156. It doesn’t have the reaching arms of a spiral galaxy nor the long shape of an elliptical, but it has characteristics of both. It has thousands of bright stars with areas of busy star formation like you’d expect to see in a spiral galaxy and the soft diffuse glow around its center suggests an elliptical. It’s also a small galaxy, so it’s a type classified as an irregular dwarf galaxy.

Related Videos
The Hubble Picture of the Week has a shape unlike many of the galaxies familiar to Hubble, with thousands of bright stars evoking a spiral galaxy, but it lacking the characteristic ‘winding’ structure. T
The galaxy featured in this Picture of the Week has a shape unlike many of the galaxies familiar to Hubble. Its thousands of bright stars evoke a spiral galaxy, but it lacks the characteristic ‘winding’ structure. The shining red blossoms stand out as well, twisted by clouds of dust — these are the locations of intense star formation. Yet it also radiates a diffuse glow, much like an elliptical galaxy and its core of older, redder stars. This galactic marvel is known to astronomers as NGC 1156. ESA/Hubble & NASA, R. B. Tully, R. Jansen, R. Windhorst

But NGC 1156’s unusual structure is not its only feature which makes it intriguing.”It has a variety of different features that are of interest to astronomers,” Hubble scientists write. “A dwarf irregular galaxy, it’s also classified as isolated, meaning no other galaxies are nearby enough to influence its odd shape and continuing star formation. The extreme energy of freshly formed young stars gives color to the galaxy, against the red glow of ionized hydrogen gas, while its center is densely-packed with older generations of stars.”

This image is an updated version with new data, following a previous Hubble image of the galaxy released in 2019. A telescope like Hubble is extremely over-subscribed, meaning that many more researchers want to use it than there is time for, so every minute of observation time is precious. However, many observation programs need to use the telescope for extended periods of time, or can only be done at certain times. So there is some amount of free time when Hubble isn’t being used for other projects when it is given over to gap-filling programs like Every Known Nearby Galaxy. This project observes nearby galaxies like NGC 1156 to get more information about the type of stars that reside within them.

Editors' Recommendations

Topics
An enormous galaxy cluster warps spacetime in this Hubble image
A massive galaxy cluster in the constellation Cetus dominates the centre of this image from the NASA/ESA Hubble Space Telescope. This image is populated with a serene collection of elliptical and spiral galaxies, but galaxies surrounding the central cluster — which is named SPT-CL J0019-2026 — appear stretched into bright arcs, as if distorted by a gargantuan magnifying glass. This cosmic contortion is called gravitational lensing, and it occurs when a massive object like a galaxy cluster has a sufficiently powerful gravitational field to distort and magnify the light from background objects.

Every week, scientists using the Hubble Space Telescope share an image from this beloved piece of space technology, and this week's image shows a vital astronomical phenomenon in action. While space telescopes can observe very far-off objects if they are bright enough, there is still a lot of the universe that is too far away to observe -- which is why researchers make use of a natural occurrence called gravitational lensing.

Gravitational lensing happens when an object like a galaxy or galaxy cluster has so much mass that it noticeably warps spacetime. Everything with mass bends spacetime somewhat, but usually this effect is so small as to be effectively invisible. But when the object is something with as much mass as a large galaxy or even a collection of galaxies, then this warping can be significant enough for us to observe it.

Read more
Three galaxies are in the process of merging in this Hubble image
A spectacular trio of merging galaxies in the constellation Boötes takes center stage in this image from the NASA/ESA Hubble Space Telescope. These three galaxies are set on a collision course and will eventually merge into a single larger galaxy, distorting one another’s spiral structure through mutual gravitational interaction in the process. An unrelated foreground galaxy appears to float serenely near this scene, and the smudged shapes of much more distant galaxies are visible in the background.

This week's image from the Hubble Space Telescope shows a dramatic collision of three different galaxies. The trio, located in the Boötes constellation, are in the process of merging and will eventually form one single large galaxy.

A spectacular trio of merging galaxies in the constellation Boötes takes center stage in this image from the NASA/ESA Hubble Space Telescope. These three galaxies are set on a collision course and will eventually merge into a single larger galaxy, distorting one another’s spiral structure through mutual gravitational interaction in the process. An unrelated foreground galaxy appears to float serenely near this scene, and the smudged shapes of much more distant galaxies are visible in the background. ESA/Hubble & NASA, M. Sun

Read more
James Webb captures swirls of dust and gas in nearby galaxies
Scientists are getting their first look with the NASA/ESA/CSA James Webb Space Telescope’s powerful resolution at how the formation of young stars influences the evolution of nearby galaxies. The spiral arms of NGC 7496, one of a total of 19 galaxies targeted for study by the Physics at High Angular resolution in Nearby Galaxies (PHANGS) collaboration, are filled with cavernous bubbles and shells overlapping one another in this image from Webb’s Mid-Infrared Instrument (MIRI). These filaments and hollow cavities are evidence of young stars releasing energy and, in some cases, blowing out the gas and dust of the interstellar medium they plough into.

The James Webb Space Telescope is helping astronomers to peer into nearby galaxies and see the elaborate structures of dust and gas which are created by and necessary for star formation.

The Physics at High Angular resolution in Nearby Galaxies, or PHANGS project, involves using data from different telescopes to look at galaxies that are close to us. By using telescopes such as the Hubble Space Telescope and the Atacama Large Millimeter/submillimeter Array, researchers can collect data in different wavelengths such as the visible light and radio wavelengths.

Read more