galaxies Archives

January 3, 2024January 3, 2024 by Evan Gough

The Oldest Known Spiral Galaxy Has Ripples Like the Surface of a Pond

This simulation illustrates a galaxy disk being disturbed, leading to the propagation of a seismic ripple throughout the disk. (Credit: Bland-Hawthorn and Tepper-Garcia, University of Sydney).

Astronomers have detected pond-like ripples across the gaseous disk of an ancient galaxy. What caused the ripples, and what do they tell us about the distant galaxy’s formation and evolution? And whatever happened, how has it affected the galaxy and its main job: forming stars?

December 29, 2023December 29, 2023 by Brian Koberlein

The Early Universe Was Surprisingly Filled With Spiral Galaxies

The bluish-white spiral galaxy NGC 1376 hangs delicately in the cold vacuum of space. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

If we could travel far beyond our galaxy, and look back upon the Milky Way, it would be a glorious sight. Luminous spirals stretching from a central core, with dust and nebulae scattered along the spiral edges. When you think about a galaxy, you probably imagine a spiral galaxy like the Milky Way, but spirals make up only about 60% of the galaxies we see. That’s because spiral galaxies only form when smaller galaxies collide and merge over time. Or so we thought, as a new study suggests that isn’t the case.

December 15, 2023December 15, 2023 by Nancy Atkinson

Hubble Sees a Random Collection of Galaxies, Perfectly Lined Up

A pair of interacting galaxies, one smaller than the other. Each has a bright spot at the centre and two loosely-wound spiral arms, with threads of dark dust following the arms. They appear as a broad, soft glow in which individual stars can’t be seen. A number of bright stars and smaller, background galaxies can also be seen — three such galaxies lie in a vertical line below the right-hand galaxy of the pair.

This new image from the Hubble Space Telescope looks like a series of smaller spiral galaxies are falling out of a larger and brighter galaxy. That’s just one of the many reasons this collection of galaxies belongs to the Arp-Madore catalogue of peculiar galaxies.

December 8, 2023December 9, 2023 by Brian Koberlein

Did the Last Great Galactic Merger Create the Milky Way's Bar?

Milky Way. Image credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

The Milky Way is a spiral galaxy. More specifically, it is a barred spiral galaxy, meaning that within its central region, there is a bar shape off of which the spirals emanate. About two-thirds of spiral galaxies are barred spirals, and astronomers have thought this difference is just a variance in how density waves cluster stars in a galaxy. But a new study suggests that the bar of the Milky Way may have been caused by an ancient collision with another galaxy.

November 26, 2023November 26, 2023 by Carolyn Collins Petersen

The Early Universe Had No Problem Making Barred Spiral Galaxies

An artist's conception of the CEERS-2112 galaxy in the early Universe. Credit: Luca Costantin/CAB/CSIC-INTA

Spiral galaxies like the Milky Way are like cosmic snowflakes—no two are exactly alike. For many years, astronomers thought spirals couldn’t exist until the universe was about half its present age. Now, a newly discovered galaxy in the early Universe is challenging that idea.

November 23, 2023November 23, 2023 by Evan Gough

Adolescent Galaxies are Incandescent and Contain Unexpected Elements

Light from 23 distant galaxies, identified with red rectangles in the Hubble Space Telescope image at the top, were combined to capture incredibly faint emission from eight different elements, which are labelled in the JWST spectrum at the bottom. Although scientists regularly find these elements on Earth, astronomers rarely, if ever, observe many of them in distant galaxies, especially nickel. Image Credit: Aaron M. Geller, Northwestern, CIERA + IT-RCDS

If the Universe has adolescent galaxies, they’re the ones that formed about 2 to 3 billion years after the Big Bang. New research based on the James Webb Space Telescope shows that these teenage galaxies are unusually hot. Not only that, but they contain some unexpected chemical elements. The most surprising element found in these galaxies is nickel.

November 23, 2023November 23, 2023 by Evan Gough

There Aren’t Many Galaxies Like The Milky Way Nearby. Now We Know Why

Antennas of the Very Large Array against the Milky Way. Credit: NRAO/AUI/NSF/Jeff Hellerman

The Milky Way is a barred spiral galaxy, maybe even a grand design spiral galaxy. We can’t be sure from our vantage point. But one thing is certain: there aren’t many disk galaxies like it in our part of the Universe called the supergalactic plane.

November 21, 2023November 21, 2023 by Evan Gough

A Galaxy Only 350 Million Years Old Had Surprising Amounts of Metal

The JWST has the power to see the most ancient galaxies in the Universe, as shown in this image of its first deep field. Now, astrophysicists have found carbon in one of these ancient galaxies. Image Credit: NASA, ESA, CSA, and STScI

Astrophysicists working with the JWST have found a surprising amount of metal in a galaxy only 350 million years after the Big Bang. How does that fit in with our understanding of the Universe?

November 18, 2023November 18, 2023 by Brian Koberlein

The Universe Can't Hide Behind the Zone of Avoidance Any Longer

The central region of the Milky Way, also known as the Zone of Avoidance. Credit: ESO/S. Brunier

Our view of the cosmos is always limited by the fact we are located within a galaxy filled with interstellar gas and dust. This is most dramatically seen in the central region of the Milky Way, which is filled with so much dust that it is sometimes referred to as the Zone of Avoidance. Within this zone, our observations of extragalactic objects are limited, but that is starting to change.

November 12, 2023November 12, 2023 by Mark Thompson

Mystery Solved. How We Get Ultra-Compact Dwarf Galaxies

This NASA/ESA Hubble Space Telescope image shows the dwarf galaxy M60-UDC1. Lying about 50 million light-years away, M60-UCD1 is a tiny galaxy with a diameter of 300 light-years — just 1/500th of the diameter of the Milky Way! Despite its size it is pretty crowded, containing some 140 million stars. The dwarf galaxy may actually be the stripped remnant of a larger galaxy that was torn apart during a close encounter with its neighbour, a massive galaxy called Messier 60. Circumstantial evidence for this comes from the recent discovery of a monster black hole, which is not visible in this image, at the centre of the dwarf. The black hole makes up 15 percent of the mass of the entire galaxy, making it much too big to have formed inside a dwarf galaxy. — Ultra Compact Dwarf Galaxy M60-UCD1 (Credit NASA/ESA and A.Seth)

I have been fascinated by galaxies for most of my adult life. I find it amazing that, just as we can ascertain the lifecycle of a tree by closely studying the trees in a forest, it is possible to study a sample of galaxies and understand galactic evolution. A team of astronomers using the Gemini North Telescope have recently solved a long standing galactic mystery, namely how we get ultra-compact dwarf galaxies (UCDs to use their catchy acronym).