Galaxies are often called the jewels of the universe, since they are enormous assemblies of stars, gas, dust, and dark matter, each with its own shape and history.
NASA’s Chandra X-ray Observatory, in cooperation with other major telescopes, provides a new view of these cosmic gems.
The newly processed images highlight the remarkable variety of galaxies, from beautiful spirals to chaotic mergers, and show the energetic processes that give them their form.
Supercomputing reveals fossil record of galaxy’s historyMost telescopes capture visible light, but Chandra specializes in X-rays, a form of high-energy radiation.
This process enriches the universe with life‑forming elements, while supermassive black holes, through their jets and outbursts, can reshape entire galaxies.
Galaxies are often called the jewels of the universe, since they are enormous assemblies of stars, gas, dust, and dark matter, each with its own shape and history.
NASA’s Chandra X-ray Observatory, in cooperation with other major telescopes, provides a new view of these cosmic gems. The newly processed images highlight the remarkable variety of galaxies, from beautiful spirals to chaotic mergers, and show the energetic processes that give them their form.
Astronomers typically sort galaxies into three broad categories: Spirals, like our own Milky Way, with graceful arms winding out from a central bulge; Elliptical galaxies, in contrast to the others, are generally older and smoother and have often come about as a result of mergers; while the irregular galaxies refuse neat classification and have unusual or disrupted structures.
Galaxies, just like gemstones, contain a record of the Earth’s geological history and thus allow scientists to gain insights into both the past and the possible future of the Milky Way.
Supercomputing reveals fossil record of galaxy’s history
Most telescopes capture visible light, but Chandra specializes in X-rays, a form of high-energy radiation. X-rays reveal phenomena invisible to ordinary light:
Gas is heated to millions of degrees by winds from stars, blasts from black holes, and material from exploded stars. This process enriches the universe with life‑forming elements, while supermassive black holes, through their jets and outbursts, can reshape entire galaxies.
By combining Chandra’s X-ray vision with data from telescopes like James Webb, Hubble, NuSTAR, and IXPE, astronomers can build a more complete picture of how galaxies live, interact, and evolve.
In face-on spirals such as Messier 33 and NGC 3938, the star-forming areas located in their arms are illuminated by cosmic explosions and by pairs of bright stars. In barred spirals such as NGC 1672 and NGC 1385, the central bars direct gas toward the center, triggering bursts of new star formation.
Chandra determined what causes a galaxy’s wind to blow
Other galaxies show what happens after collisions. NGC 4725 illustrates the way a previous encounter has led to the formation of new stars. Edge-on spirals such as the Whale Galaxy (NGC 4631) and the Cigar Galaxy (Messier 82) display huge halos and superwinds, which are million-degree gas clouds blown thousands of light-years into space by stellar explosions and thus enrich the intergalactic medium.
At the center of the galaxy, there are active galactic nuclei (AGN), which are supermassive black holes that feed on material surrounding them and produce powerful jets. In the case of Centaurus A, observations made with Chandra and IXPE show a particle jet extending for tens of thousands of light-years.
In the case of Messier 106, jets driven by a black hole heat the surrounding gas and thus shape the spiral arms in a way that is different from those found in ordinary galaxies. In the Sombrero Galaxy (Messier 104), a black hole lies within a large stellar bulge, and Chandra has mapped a diffuse halo of gas at a temperature of one million degrees surrounding its well-known dust lanes.
Some galaxies in the gallery are caught in the act of transformation. Arp 143 resembles a cosmic bullseye, where a direct collision created a ring galaxy and waves of star birth. NGC 3256 and II Zw 096 reveal violent mergers cloaked in dust, echoing the chaotic collisions that dominated the early universe, and foreshadowing the Milky Way’s eventual merger with Andromeda.
Other unusual examples are NGC 1569, a nearby galaxy undergoing a burst of star formation which acts as a kind of laboratory for the conditions that existed in the early universe; NGC 660, a rare ‘polar ring’ galaxy having stars that orbit around its poles; and Messier 90, a spiral galaxy moving through the Virgo Cluster while losing the gas responsible for star formation in the process.
These 16 pictures put together create a sort of museum display of galactic life and show galaxies as dynamic and evolving systems, which at times are serene and at other times violent, yet always reshape themselves and their surroundings.
