milky way Archives

January 12, 2023January 12, 2023 by Matt Williams

Astronomers use the World's Biggest Radio Telescope to map new Features of the Milky Way

Artist impression of a fast radio burst. Credit: Danielle Futselaar

Despite everything astronomers have learned about the nature and structure of galaxies, there are still mysteries about the Milky Way. The reason for this is simple: since we are embedded in the Milky Way’s disk, we have difficulty mapping it and observing it as a whole. It’s also very challenging to observe the center of the galaxy, what lies beyond it, and features in the disk itself because of all the gas and dust between stars- the Interstellar Medium (ISM). However, by observing the Milky Way in the non-visible spectrum (radio, x-ray, gamma-ray, etc.), astronomers can see more of what’s out there.

There’s also the spectral line that corresponds to the emission frequency (1420 MHz) of cold neutral hydrogen gas (HI), which makes up the majority of the ISM. Using the Five-hundred-meter Aperture Spherical Telescope (FAST) – the most powerful radio telescope in the world near Guizhou, China – a team of scientists located more than 500 new faint pulsars. During the survey, the team simultaneously recorded the spectral line data with high spectral and spatial resolution, making it an extremely valuable resource for studying the structure of the Milky Way Galaxy and the life cycle of its stars.

January 10, 2023January 10, 2023 by Carolyn Collins Petersen

Newly Found Stars are Technically in the Milky Way, but They’re Halfway to Andromeda

This illustration shows the Milky Way galaxy's inner and outer halos. A halo is a spherical cloud of stars surrounding a galaxy. (Image Credits: NASA, ESA, and A. Feild [STScI]) — This illustration shows the Milky Way galaxy's inner and outer halos. A halo is a spherical cloud of stars surrounding a galaxy. A population of RR Lyrae variables in the halo is giving clues to its distance. (Image Credits: NASA, ESA, and A. Feild [STScI])

We all know our galaxy, the Milky Way, is big. Really big. But, exactly how far out does it extend? Where are the outer limits? Astronomers aren’t exactly sure, precisely. However, a study of galaxies in the Virgo Cluster accidentally turned up a population of stars in the outer part of the Milky Way. They may answer those questions.

December 9, 2022December 12, 2022 by Matt Williams

A new 3D map of the Milky Way Uses close to 66,000 Stars and Reveals New Details About the Shape of our Galaxy

The warping of the Milky Way disk. Credit: University of Warsaw

In the 17th century, Galileo Galilee aimed his telescope at the stars and demonstrated (for the first time) that the Milky Way was not a nebulous band but a collection of distant stars. This led to the discovery that our Sun was merely one of the countless stars in a much larger structure: the Milky Way Galaxy. By the 18th century, William Herschel became the first astronomer to create a map that attempted to capture the shape of the Milky Way. Even after all that time and discovery, astronomers are still plagued by the problem of perspective.

While we have been able to characterize galaxies we see across the cosmos with relative ease, it is difficult for astronomers to study the size, shape, and population of the Milky Way because of how our Solar System is embedded in its disk. Luckily, there are methods to circumvent this problem of perspective, which have provided astronomers with clues to these questions. In a recent paper, a team from the Astronomical Observatory at the University of Warsaw (AstroUW) used a large collection of Mira variable stars to trace the shape of the Milky Way, which yielded some interesting results!

November 22, 2022November 22, 2022 by Carolyn Collins Petersen

The Milky Way’s Stellar Halo Isn’t a Sphere After All

stellar halo around the milky way — The Milky Way's anatomy includes a rounded stellar halo That view is changing with new data. Image courtesy ESA.

Our galaxy’s stellar halo is giving astronomers some new food for thought. It turns out everyone thought the halo was spherical. But, it’s not. That’s news to everyone who said it was spherical. According to a new measurement done by a team at Harvard-Smithsonian Center for Astrophysics, it has a tilted, oblong football shape. This all tells astronomers an interesting tale about our galaxy’s ancient history.

September 30, 2022September 30, 2022 by Brian Koberlein

A Dwarf Galaxy Passed Close to the Milky Way and Left Ripples in its Wake

Artist's view of ripples on the edge of the Milky Way. Credit: NASA JPL-Caltech R. Hurt (SSC Caltech)

When you imagine the collision of galaxies, you probably think of something violent and transformational. Spiral arms ripped apart, stars colliding, cats and dogs living together, mass hysteria. The reality is much less dramatic. As a recent study shows, our galaxy is in a collision right now.

September 7, 2022September 7, 2022 by Matt Williams

Star Formation in the Center of the Milky Way Started at the Core and Then Worked its way out

False-color image of the region Sagittarius B1, as seen by the GALACTICNUCLEUS survey. Credit & ©: F. Nogueras-Lara et al. / MPIA

One of the biggest questions facing astronomers today concerns star formation and its role in the evolution of galaxies. In particular, astronomers are curious whether the process began in the central regions of galaxies, where stars are more tightly bound. Previous observations have shown that numerous galaxies experienced intense periods of star formation in their centers roughly one billion years after the Big Bang. For some time, astronomers have wanted to conduct similar observations of the Milky Way’s Galactic Center to study rapid star formation more closely.

Unfortunately, it has been very difficult for astronomers to study the center of the Milky Way because of how bright and densely packed the region is, which makes it difficult to discern individual stars and clusters. Thanks to a new analysis of a high-resolution infrared survey, a team of astronomers has created the first reconstruction of the star formation history in the Galactic Center. According to their findings, most young stars in this region formed in loose stellar associations that dispersed outwards to fill the Galactic Disk over the course of many eons (as opposed to tightly-knit massive clusters).

May 19, 2022May 19, 2022 by Carolyn Collins Petersen

Is This the Future of the Milky Way?

The central region of the giant elliptical galaxy NGC 474. It's set against a backdrop of more distant galaxies. Will the Milky Way resemble this galaxy in the distant future? This image was taken using the Hubble Advanced Camera for Surveys, and includes data from the Wide Field and Planetary Camera 3. (Courtesy NASA/STScI.) — The central region of the giant elliptical galaxy NGC 474. It’s set against a backdrop of more distant galaxies. Will the Milky Way resemble this galaxy in the distant future? This image was taken using the Hubble Advanced Camera for Surveys, and includes data from the Wide Field and Planetary Camera 3. (Courtesy NASA/STScI.)

Take a good look at the latest image provided by the Hubble Space Telescope. It shows a huge elliptical galaxy called NGC 474 that lies about 100 million light-years away from us. At about two and a half times larger than our Milky Way Galaxy, it’s really a behemoth. Notice its strange structure—mostly featureless and nearly round, but with layered shells wrapped around the central core. Astronomers want to know what caused these shells. The answer might be in what this galaxy represents: a vision of the future Milky Way and the Andromeda Galaxy.

April 22, 2022April 22, 2022 by Shawn DiCenza

Slimmed Down Red Giants Had Their Mass Stolen By a Companion Star

Millions of stars that can grow up to 620 million miles in diameter, known as ‘red giants,’ exist in our galaxy, but it has been speculated for a while that there are some that are possibly much smaller. Now a team of astronomers at the University of Sydney have discovered several in this category and have published their findings in the journal Nature Astronomy.

“It’s like finding Wally… we were extremely lucky to find about 40 slimmer red giants, hidden in a sea of normal ones. The slimmer red giants are either smaller in size or less massive than normal red giants.”
PhD candidate Mr Yaguang Li from the University of Sydney, as quoted from the source article.

April 4, 2022April 4, 2022 by Matt Williams

The Milky Way has an Inner Ring, Just Outside the Core

This image from the NASA/ESA Hubble Space Telescope reveals a spiral galaxy named Messier 95 (also known as M95 or NGC 3351). Located about 35 million light-years away in the constellation of Leo (The Lion), this swirling spiral was discovered by astronomer Pierre Méchain in 1781, and catalogued by French astronomer Charles Messier just four days later. Messier was primarily a comet hunter, and was often left frustrated by objects in the sky that resembled comets but turned out not to be. To help other astronomers avoid confusing these objects in the future, he created his famous catalogue of Messier objects. Most definitely not a comet, Messier 95 is actually a barred spiral galaxy. The galaxy has a bar cutting through its centre, surrounded by an inner ring currently forming new stars. Also our own Milky Way is a barred spiral. As well as hosting this stellar nursery, Messier 95 is a known host of the dramatic and explosive final stages in the lives of massive stars: supernovae. In March 2016 a spectacular supernova named SN 2012aw was observed in the outer regions of one of Messier 95’s spiral arms. Once the light from the supernova had faded, astronomers were able to compare observations of the region before and after the explosion to find out which star had “disappeared” — the progenitor star. In this case, the star was an especially huge red supergiant up to 26 times more massive than the Sun.

In the past century, astronomers have learned a great deal about the cosmos and our place in it. From discovering that the Universe is in a constant state of expansion to the discovery of the Cosmic Microwave Background (CMB) and the Big Bang cosmological model, our perception of the cosmos has expanded immensely. And yet, many of the most profound astronomical discoveries still occur within our cosmic backyard – the Milky Way Galaxy.

Compared to other galaxies, which astronomers can resolve with relative ease, the structure and size of the Milky Way have been the subject of ongoing discovery. The most recent comes from the Max Planck Institute for Extraterrestrial Physics (MPE), where scientists have found a previously undiscovered inner ring of metal-rich stars just outside the Galactic Bar. The existence of this ring has revealed new insights into star formation in this region of the galaxy during its early history.

March 29, 2022March 29, 2022 by Evan Gough

Part of the Milky Way Is Much Older Than Previously Believed

Basic structure of our home galaxy, edge-on view. The new results from ESA's Gaia mission provide for a reconstruction of the history of the Milky Way, in particular of the evolution of the so-called thick disc. Image Credit: Stefan Payne-Wardenaar / MPIA

The Milky Way is older than astronomers thought, or part of it is. A newly-published study shows that part of the disk is two billion years older than we thought. The region, called the thick disk, started forming only 0.8 billion years after the Big Bang.