A Stellar Stream of Stars, Stolen from Another Galaxy

The all-sky view that the Gaia survey would have of a simulated Milky-Way-like galaxy. [Credit: Sanderson et al. The Astrophysical Journal, January 6, 2020, DOI: 10.3847/1538-4365/ab5b9d]

Modern professional astronomers aren’t much like astronomers of old. They don’t spend every suitable evening with their eyes glued to a telescope’s eyepiece. You might be more likely to find them in front of a super-computer, working with AI and deep learning methods.

One group of researchers employed those methods to find a whole new collection of stars in the Milky Way; a group of stars which weren’t born here.

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The Solar System Might Not Exist if There Wasn’t a Huge Galactic Collision with the Milky Way Billions of Years Ago

Artist's conception of a solar system in formation. Water-rich asteroids in the nebula likely delivered water to places like Earth. Credit: NASA/FUSE/Lynette Cook

The Milky Way has a number of satellite galaxies; nearly 60 of them, depedending on how we define them. One of them, called the Sagittarius Dwarf Spheroidal Galaxy (Sgr d Sph), may have played a huge role when it comes to humans, our world and our little civilization. A collision between the Milky Way and the Sgr d Sph may have created the Solar System itself.

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The Disk of the Milky Way is Warped Because it Already Collided With Another Galaxy

Credit and Copyright: Stefan Payne-Wardenaar; Magellanic Clouds: Robert Gendler/ESO

For decades, astronomers have been trying to understand why the Milky Way galaxy is warped the way it is. In recent years, astronomers have theorized that it could be our neighbors, the Magellanic Clouds, that are responsible for this phenomenon. According to this theory, these dwarf galaxies pull on the Milky Way’s dark matter, causing oscillations that pull on our galaxy’s supply of hydrogen gas.

However, according to new data from the European Space Agency’s (ESA) star-mapping Gaia Observatory, it is possible that this warp is the result of an ongoing collision with a smaller galaxy. These findings confirm that the warp in our galaxy is not static, but subject to change over time (aka. precession), and that this process is happening faster than anyone would have thought!

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An Upcoming Impact With the Magellanic Clouds is Already Causing Star Formation in the Milky Way

A newfound cluster of young stars (blue star) sits on the periphery of the Milky Way. These stars probably formed from material originating from neighboring dwarf galaxies called the Magellanic Clouds. Credit: NASA/D. Nidever

For some time, astronomers have known that collisions or mergers between galaxies are an integral part of cosmic evolution. In addition to causing galaxies to grow, these mergers also trigger new rounds of star formation as fresh gas and dust are injected into the galaxy. In the future, astronomers estimate that the Milky Way Galaxy will merge with the Andromeda Galaxy, as well as the Small and Large Magellanic Clouds in the meantime.

According to new results obtained by researchers at the Flatiron Institute’s Center for Computational Astrophysics (CCA) in New York city, the results of our eventual merger with the Magellanic Clouds is already being felt. According to results presented at the 235th meeting of the American Astronomical Society this week, stars forming in the outskirts of our galaxy could be the result of these dwarf galaxies merging with our own.

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Thanks to Gaia, we Now Know Exactly How Big Europa is

The fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution. Credits: NASA/JPL-Caltech/SETI Institute

Jupiter’s moon Europa continues to be a source of wonder and scientific intrigue. As one of the four Galilean Moons (so-named because of their founder, Galileo Galilee), Europa is one of Jupiter’s largest satellites and is considered one of the best bets for finding extraterrestrial life in the Solar System. And recently, it joined its cousins (Io and Callisto) in passing in front of a star.

This type of rare event (a stellar occultation) allows astronomers to conduct unique observations of a celestial body. In Europa’s case, the occultation took place in 2017 and allowed astronomers to make more precise measurements of Europa’s size, its position relative to Jupiter, and its true shape. All this was made possible by the ESA’s Gaia Observatory, which let astronomers know exactly when and where to look for the moon.

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What Did the Early Milky Way Look Like?

The Milky Way 10 billion years ago and the Milky Way today. Image Credit: Gabriel Pérez Díaz, SMM (IAC)

In the very early days of our Universe, just over 13 billion years ago, there was very little structure. There were stars, and they were forming at a rapid rate, kicking off what’s known as the Stelliferous Era. But the enormous, majestic galaxies that we see today, including our Milky Way galaxy, hadn’t formed yet.

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Gaia Mission is Mapping Out the Bar at the Center of the Milky Way

Credit: Data: ESA/Gaia/DPAC, A. Khalatyan(AIP) & StarHorse team; Galaxy map: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Despite the many advancements made in the field of astronomy, astronomers still struggle to get an accurate assessment of the Milky Way Galaxy. Because we are embedded in its disk, it is much more difficult to assess its size, structure, and extent – unlike galaxies located millions (or billions) of light-years away. Luckily, thanks to improved instruments and tireless efforts, progress is being made all the time.

For instance, a team of astronomers recently combined the latest data obtained by the ESA’s Gaia observatory with the infrared and optical observations of other telescopes to start mapping the bar-shaped collection of stars at the center of our Milky Way. This constitutes the first time in history that astronomers have been able to make direct measurements of this barred structure.

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In the far Future our Sun will Turn Into a Solid Crystalline White Dwarf. Here’s How it’ll Happen

Artist's impression of the crystallization in the interior of a white dwarf star. Credit: University of Warwick/Mark Garlick

About fifty years ago, astronomers predicted what the ultimate fate of our Sun will be. According to the theory, the Sun will exhaust its hydrogen fuel billions of years from now and expand to become a Red Giant, followed by it shedding it’s outer layers and becoming a white dwarf. After a few more billion years of cooling, the interior will crystallize and become solid.

Until recently, astronomers had little evidence to back up this theory. But thanks to the ESA’s Gaia Observatory, astronomers are now able to observe hundreds of thousands of white dwarf stars with immense precision – gauging their distance, brightness and color. This in turn has allowed them to study what the future holds for our Sun when it is no longer the warm, yellow star that we know and love today.

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Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves

NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA
NASA's Solar Dynamics Observatory has captured images of a growing dark region on the surface of the Sun. Called a coronal hole, it produces high-speed solar winds that can disrupt satellite communications. Image: Solar Dynamics Observatory / NASA

How in the world could you possibly look inside a star? You could break out the scalpels and other tools of the surgical trade, but good luck getting within a few million kilometers of the surface before your skin melts off. The stars of our universe hide their secrets very well, but astronomers can outmatch their cleverness and have found ways to peer into their hearts using, of all things, sound waves. Continue reading “Scientists are Using Artificial Intelligence to See Inside Stars Using Sound Waves”

Gaia Spots an Enormous Ghost Galaxy Right Next Door that’s Being Dismantled by the Milky Way

From left to right: Large Magellanic Cloud, the Milky Way, and Antlia 2, our next door neighbor and so-called ghost galaxy. Credit: V. Belokurov based on the images by Marcus and Gail Davies and Robert Gendler
From left to right: Large Magellanic Cloud, the Milky Way, and Antlia 2, our next door neighbor and so-called ghost galaxy. Credit: V. Belokurov based on the images by Marcus and Gail Davies and Robert Gendler

Astronomers combing through data from the ESA’s Gaia spacecraft have discovered what they’re calling a ghost galaxy. The galaxy, named Antlia 2 (Ant 2) is an extremely low-density dwarf galaxy that was formed in the early days of the universe. And it is being stripped of its mass by the tidal forces of the Milky Way.
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