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

Astronomers have found our Milky Way’s galactic twin

By

Astronomers have spotted an oddity from the ancient universe: An extremely distant young galaxy which looks unexpectedly similar to our Milky Way.

The galaxy, known by the not terribly pithy name of SPT0418-47, is located so far away that light from it takes more than 12 billion years to reach us. This means that observing it is like looking back in time to when the universe was very young, at just 1.4 billion years old. And surprisingly, the galaxy looks remarkably like our own, much older galaxy.

Scientists had previously believed that all galaxies which formed in the early universe were chaotic and unstable, unlike our relatively sedate galaxy. But this new finding challenges that belief.

Related

“This result represents a breakthrough in the field of galaxy formation, showing that the structures that we observe in nearby spiral galaxies and in our Milky Way were already in place 12 billion years ago,” lead researcher Francesca Rizzo, Ph.D. student from the Max Planck Institute for Astrophysics in Germany, said in a statement.

an extremely distant galaxy that looks surprisingly like our Milky Way
Astronomers using ALMA have revealed an extremely distant galaxy that looks surprisingly like our Milky Way. The galaxy, SPT0418-47, is gravitationally lensed by a nearby galaxy, appearing in the sky as a near-perfect ring of light. ALMA (ESO/NAOJ/NRAO), Rizzo et al.

The image of the galaxy shown above appears in a ring shape due to the way in which the data about it was collected. As the galaxy is so far away, it is impossible to see using typical methods. So the team collected data with the Atacama Large Millimeter/submillimeter Array (ALMA) by using a nearby galaxy as a magnifying glass, with a technique called gravitational lensing.

Then, to see the distant galaxy as it actually exists, they reconstructed a realistically shaped image from this ring using computer modeling.

“When I first saw the reconstructed image of SPT0418-47 I could not believe it,” Rizzo said. “A treasure chest was opening.”

Reconstructed view of SPT0418-47
The research team reconstructed the distant galaxy’s true shape, shown here, and the motion of its gas from the ALMA data using a new computer modeling technique. ALMA (ESO/NAOJ/NRAO), Rizzo et al.

When looking at this reconstructed image, the researchers could tell that the galaxy was orderly and showed features similar to much older galaxies. “The big surprise was to find that this galaxy is actually quite similar to nearby galaxies, contrary to all expectations from the models and previous, less detailed, observations,” co-author Filippo Fraternali, from the Kapteyn Astronomical Institute, University of Groningen in the Netherlands said in the statement.

This raises questions as to how such an orderly galaxy was able to form in the chaos of the early universe, and indicates that our previous assumptions about galactic evolution may be incorrect.

“What we found was quite puzzling; despite forming stars at a high rate, and therefore being the site of highly energetic processes, SPT0418-47 is the most well-ordered galaxy disc ever observed in the early universe,” explained co-author Simona Vegetti, also from the Max Planck Institute for Astrophysics. “This result is quite unexpected and has important implications for how we think galaxies evolve.”

The findings are published in the journal Nature.

Editors’ Recommendations

Topics
Georgina Torbet
Georgina Torbet
Space Writer
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Astronomers find remnants of planets around 10 billion-year-old stars
Artist’s impression of the old white dwarfs WDJ2147-4035 and WDJ1922+0233 surrounded by orbiting planetary debris, which will accrete onto the stars and pollute their atmospheres. WDJ2147-4035 is extremely red and dim, while WDJ1922+0233 is unusually blue.

Far away in the depths of the Milky Way lie two small, dim stars that are in the final stage of their life. At over 10 billion years old, white dwarfs WDJ2147-4035 and WDJ1922+0233 are among the oldest stars in our galaxy, and recently, astronomers discovered something special orbiting around them: the remains of planets, making this one of the oldest known rocky planetary systems.

Astronomers used data from GAIA, the Dark Energy Survey, and the X-Shooter instrument at the European Southern Observatory to peer at this system. They identified debris from orbiting planetesimals, which are globs of dust and rock which are created during planetary formation. The researchers used spectroscopy to look at the light coming from the two white dwarf stars and break it down into different wavelengths, which can show what materials the stars and the surrounding matter are made of.

Read more
Astronomers spot a monster black hole ‘practically in our backyard’
The cross-hairs mark the location of the newly discovered monster black hole.

Black holes come in a variety of sizes, from stellar black holes a few times the mass of the sun all the way up to supermassive black holes, which are millions of times the mass of the sun and lurk at the heart of galaxies. Recently, astronomers discovered a massive black hole just 1,550 light-years away, which is right in our neighborhood, astronomically speaking. It is one of the closest black holes ever discovered, with a mass 12 times that of the sun. Being so close to us, it's an exciting target for future research.

The cross-hairs mark the location of the newly discovered monster black hole. Sloan Digital Sky Survey / S. Chakrabart et al.

Read more
This galaxy helps astronomers measure the size of the universe
The NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 imaged this lonely spiral galaxy called UGC 9391. The galaxy resides 130 million light-years from Earth in the constellation Draco near the north celestial pole. Its star-studded spiral arms stand in splendid isolation against a backdrop of distant galaxies, which are only visible as indistinct swirls or smudges thanks to their vast distances from Earth.

Trying to measure the size of the universe is no easy task. We know that the universe is expanding, though the exact rate of this expansion is not yet fixed. So one method that astronomers use to tell how far away very distant objects are is called the cosmic distance ladder. The idea is that different objects can be used as rungs on a ladder for measuring different distances, from looking at the movements of stars to observing pulsating stars called cepheid variables to observing a type of supernova called a Type Ia.

Each of these classes of objects is useful for determining increasingly large distances, but they need to be calibrated to each other to be accurate. Cepheid variables change in brightness over time, and importantly, the speed of the changes in brightness is correlated to their true brightness (as opposed to how bright they appear in the sky). So when we see a star pulsing we can work out its true brightness, and by comparing this to its apparent brightness, we can work out how far away it is.

Read more