galaxies Archives

January 14, 2022January 14, 2022 by Evan Gough

Nancy Grace Roman Telescope Will do its Own, Wide-Angle Version of the Hubble Deep Field

This synthetic image visualizes what a Roman ultra-deep field could look like. The 18 squares at the top of this image outline the area Roman can see in a single observation, known as its footprint. The inset at the lower-right zooms into one of the squares of Roman's footprint, and the inset at the lower-left zooms in even further. The image, which contains more than 10 million galaxies, was constructed from a simulation that produced a realistic distribution of the galaxies in the universe. Image Credit: Nicole Drakos, Bruno Villasenor, Brant Robertson, Ryan Hausen, Mark Dickinson, Henry Ferguson, Steven Furlanetto, Jenny Greene, Piero Madau, Alice Shapley, Daniel Stark, Risa Wechsler

Remember the Hubble Space Telescope’s Deep Field and Ultra-Deep Field images?

Those images showed everyone that what appears to be a tiny, empty part of the sky contains thousands of galaxies, some dating back to the Universe’s early days. Each of those galaxies can have hundreds of billions of stars. These early galaxies formed only a few hundred million years after the Big Bang. The images inspired awe in the human minds that took the time to understand them. And they’re part of history now.

The upcoming Nancy Grace Roman Space Telescope (NGRST) will capture its own version of those historical images but in wide-angle. To whet our appetites for the NGRST’s image, a group of astrophysicists have created a simulation to show us what it’ll look like.

December 29, 2021December 29, 2021 by Brian Koberlein

If you had Radio Telescopes for Eyes, one of the Biggest Things in the sky Would be a jet of Material Blasting out of a Nearby Galaxy

Merging X-ray data (blue) from NASA’s Chandra X-ray Observatory with microwave (orange) and visible images reveals the jets and radio-emitting lobes emanating from Centaurus A's central black hole. Credit: ESO/WFI (visible); MPIfR/ESO/APEX/A.Weiss et al. (microwave); NASA/CXC/CfA/R.Kraft et al. (X-ray)

One concept that’s difficult to visualize is the apparent size of objects in the sky. No the actual size of an object, but rather the amount of area an object covers in the sky. Apparent size depends on an object’s actual size and its distance from us. For example, the Sun is about 400 times wider than the Moon, but also about 400 times more distant, so the Sun and Moon have roughly the same apparent size.

December 18, 2021December 15, 2021 by Paul M. Sutter

Astronomy Jargon 101: Irregular Galaxies

The dwarf galaxy UGC 5189A, site of the supernova SN 2010jl. Image Credit: ESO

In this series we are exploring the weird and wonderful world of astronomy jargon! You’ll feel a little odd after today’s topic: irregular galaxies!

December 18, 2021December 15, 2021 by Paul M. Sutter

Astronomy Jargon 101: Galactic Halo

This NASA/ESA Hubble Space Telescope image shows a compact and distant globular star cluster that lies in one of the smallest constellations in the night sky, Delphinus (The Dolphin). Due to its modest size, great distance and relatively low brightness, NGC 7006 is often ignored by amateur astronomers. But even remote globular clusters such as this one appear bright and clear when imaged by Hubble’s Advanced Camera for Surveys. NGC 7006 resides in the outskirts of the Milky Way. It is about 135 000 light-years away, five times the distance between the Sun and the centre of the galaxy, and it is part of the galactic halo. This roughly spherical region of the Milky Way is made up of dark matter, gas and sparsely distributed stellar clusters. Like other remote globular clusters, NGC 7006 provides important clues that help astronomers to understand how stars formed and assembled in the halo. The cluster now pictured by Hubble has a very eccentric orbit indicating that it may have formed independently, in a small galaxy outside our own that was then captured by the Milky Way. Although NGC 7006 is very distant for a Milky Way globular cluster, it is much closer than the many faint galaxies that can be seen in the background of this image. Each of these faint smudges is probably accompanied by many globular clusters similar to NGC 7006 that are too faint to be seen even by Hubble. This image was taken using the Wide Field Channel of the Advanced Camera for Surveys, in a combination of visible and near-infrared light. The field of view is a little over 3 by 3 arcminutes.

In this series we are exploring the weird and wonderful world of astronomy jargon! You’ll wrap your head around today’s topic: galactic halo!

November 29, 2021November 29, 2021 by Nancy Atkinson

A Gravitational Lens Shows the Same Galaxy Three Times

This star- and galaxy-studded image was captured by Hubble’s Wide Field Camera 3 (WFC3). The galaxy visible in the bottom right corner of the image, named SGAS 0033+02 is a triple gravitational lens. Credit: ESA/Hubble & NASA, E. Wuyts.

Images from the Hubble Space Telescope are often mind-bending in both their beauty and wealth of scientific wonder. And sometimes, Hubble captures light-bending images too.

Hubble’s Wide Field Camera 3 (WFC3) snapped a photo of a galaxy where the light has been bent by gravitational lensing, so that the galaxy show up not just once, but three times. But the multiple views aren’t exact replicas of each other — they appear as different shapes.

November 15, 2021November 15, 2021 by Nancy Atkinson

A Black Hole has been Found Lurking Just Outside the Milky Way

This artist’s impression shows a compact black hole 11 times as massive as the Sun and the five-solar-mass star orbiting it. The two objects are located in NGC 1850, a cluster of thousands of stars roughly 160 000 light-years away in the Large Magellanic Cloud, a Milky Way neighbour. The distortion of the star’s shape is due to the strong gravitational force exerted by the black hole. Not only does the black hole’s gravitational force distort the shape of the star, but it also influences its orbit. By looking at these subtle orbital effects, a team of astronomers were able to infer the presence of the black hole, making it the first small black hole outside of our galaxy to be found this way. For this discovery, the team used the Multi Unit Spectroscopic Explorer (MUSE) instrument at ESO’s Very Large Telescope in Chile. Credit: ESO/M. Kornmesser

Astronomers have found a smaller, stellar-mass black hole lurking in a nearby satellite galaxy of our own Milky Way. The black hole has been hiding in a star cluster named NGC 1850, which is one of the brightest star clusters in the Large Magellanic Cloud. The black hole is 160,000 light-years away from Earth, and is estimated to be about 11 times the mass of our Sun.

August 11, 2021August 11, 2021 by Andy Tomaswick

It Turns out There Were Supernovae Exploding all Over, we Just Couldn’t see Them

When the poet Horace said “We are but dust and shadow”, he probably didn’t think that dust itself could create a shadow. But it can, and that shadow can obscure even some of the most powerful explosions in the universe. At least that’s the finding from new research from an international team using data from the recently retired Spitzer telescope. It turns out dust in far away galaxies can obscure supernovas.

June 17, 2021June 21, 2021 by Evan Gough

The Largest Rotating Objects in the Universe: Galactic Filaments Hundreds of Millions of Light-Years Long

Artist’s impression of cosmic filaments: huge bridges of galaxies and dark matter connect clusters of galaxies to each other. Galaxies are funnelled on corkscrew like orbits towards and into large clusters that sit at their ends. Their light appears blue-shifted when they move towards us, and red-shifted when they move away. Credit: AIP/ A. Khalatyan/ J. Fohlmeister

We’ve known for a while about the large-scale structure of the Universe. Galaxies reside in filaments hundreds of millions of light-years long, on a backbone of dark matter. And, where those filaments meet, there are galaxy clusters. Between them are massive voids, where galaxies are sparse. Now a team of astronomers in Germany and their colleagues in China and Estonia have made an intriguing discovery.

These massive filaments are rotating, and this kind of rotation on such a massive scale has never been seen before.

February 5, 2021February 5, 2021 by Evan Gough

Astronomers Can Predict When a Galaxy’s Star Formation Ends Based on the Shape and Size of its Disk

An ensemble of twenty-five disk galaxies. The view on the left shows light emitted in the H-alpha line from interstellar gas as a result of ongoing star-formation, while the panels on the right shows the optical light emitted by a mix of young (bluer) and old (redder) stars. Each galaxy can be seen rotated edge-on below its face-on view. Image Credit: TNG Collaboration

A galaxy’s main business is star formation. And when they’re young, like youth everywhere, they keep themselves busy with it. But galaxies age, evolve, and experience a slow-down in their rate of star formation. Eventually, galaxies cease forming new stars altogether, and astronomers call that quenching. They’ve been studying quenching for decades, yet much about it remains a mystery.

A new study based on the IllustrisTNG simulations has found a link between a galaxy’s quenching and its stellar size.

February 1, 2021February 1, 2021 by Paul M. Sutter

Galaxy Mergers can Boost Star Formation, and it can Also Shut it Down

It is known today that merging galaxies play a large role in the evolution of galaxies and the formation of elliptical galaxies in particular. However there are only a few merging systems close enough to be observed in depth. The pair of interacting galaxies picture seen here — known as NGC 3921 — is one of these systems. NGC 3921 — found in the constellation of Ursa Major (The Great Bear) — is an interacting pair of disc galaxies in the late stages of its merger. Observations show that both of the galaxies involved were about the same mass and collided about 700 million years ago. You can see clearly in this image the disturbed morphology, tails and loops characteristic of a post-merger. The clash of galaxies caused a rush of star formation and previous Hubble observations showed over 1000 bright, young star clusters bursting to life at the heart of the galaxy pair.

Galaxy mergers are beautiful sights, but ultimately deadly. In the midst of the collision, the combined galaxy will shine brighter than it ever has before. But that glory comes with a price: all those new stars use up all the available fuel, and star formation grinds to a halt.