One of the ways we categorize stars is by their metallicity. That is the fraction of heavier elements a star has compared to hydrogen and helium. It’s a useful metric because the metallicity of a star is a good measure of its age.Continue reading “Some of the Milky Way’s oldest stars aren’t where they’re expected to be”
Like other spiral galaxies, the Milky Way has a bulging sphere of stars in its center. It’s called “The Bulge,” and it’s roughly 10,000 light-years in radius. Astronomers have debated the bulge’s origins, with some research showing that multiple episodes of star formation created it.
But a new survey with the NOIRLab’s Dark Energy Camera suggests that one single epic burst of star formation created the bulge over 10 billion years ago.Continue reading “The Spherical Structure at the Core of the Milky Way Formed in a Single Burst of Star Formation”
A team of researchers has discovered a complex network of filamentary structures in the Milky Way. The structures are made of atomic hydrogen gas. And we all know that stars are made mostly of hydrogen gas.
Not only is all that hydrogen potential future star-stuff, the team found that its filamentary structure is also a historical imprint of some of the goings-on in the Milky Way.Continue reading “Astronomers Map Out the Raw Material for New Star Formation in the Milky Way”
In 2005 astronomers found a dense grouping of stars in the Virgo constellation. It looked like a star cluster, except further surveys showed that some of the stars are moving towards us, and some are moving away. That finding was unexpected and suggested the Stream was no simple star cluster.
A 2019 study showed that the grouping of stars is no star cluster at all; instead, it’s the hollowed-out shell of a dwarf spheroidal galaxy that merged with the Milky Way. It’s called the Virgo Overdensity (VOD) or the Virgo Stellar Stream.
A new study involving some of the same researchers shows how and when the merger occurred and identifies other shells from the same merger.Continue reading “Astronomers Find the Hollowed-Out Shell of a Dwarf Galaxy that Collided With the Milky Way Billions of Years Ago”
The heart of the Milky Way can be a mysterious place. A gigantic black hole resides there, and it’s surrounded by a retinue of stars that astronomers call a Nuclear Star Cluster (NSC). The NSC is one of the densest populations of stars in the Universe. There are about 20 million stars in the innermost 26 light years of the galaxy.
New research shows that about 7% of the stars in the NSC came from a single source: a globular cluster of stars that fell into the Milky Way between 3 and 5 billion years ago.Continue reading “7% of the Stars in the Milky Way’s Center Came From a Single Globular Cluster That Got Too Close and Was Broken Up”
The European Space Agency launched the Gaia mission in 2013. The mission’s overall goal was to discover the history of the Milky Way by mapping out the positions and velocities of one billion stars. The result is kind of like a movie that shows the past and the future of our galaxy.
The mission has released two separate, massive data sets for researchers to work through, with a third data release expected soon. All that data has spawned a stream of studies into our home galaxy.
Recently, the ESA drew attention to five new insights into the Milky Way galaxy. Allof these discoveries directly stemmed from the Gaia spacecraft.Continue reading “Gaia has Already Given Us 5 New Insights Into the Milky Way”
Massive galaxies like our Milky Way gain mass by absorbing smaller galaxies. The Large Magellanic Cloud and the Small Magellanic Cloud are irregular dwarf galaxies that are gravitationally bound to the Milky Way. Both the clouds are distorted by the Milky Way’s gravity, and astronomers think that the Milky Way is in the process of digesting both galaxies.
A new study says that process is already happening, and that the Milky Way is enjoying the Magellanic Clouds’ halos of gas as an appetizer, creating a feature called the Magellanic Stream as it eats. It also explains a 50 year old mystery: Why is the Magellanic Stream so massive?Continue reading “The Milky Way is Already Starting to Digest the Magellanic Clouds, Starting With Their Protective Halos of Hot Gas”
An Ancient Voyage
Earth is on a journey…
While our planet orbits the Sun each year – a billion kilometers – our entire Solar System is drifting through the Milky Way Galaxy making one rotation every 225-250 million years (that means dinosaurs actually lived on the other side of the Galaxy!) Humanity has been on Earth for a small fraction of that journey, but parts of what we’ve missed is chronicled. It is written into the rock and life of our planet by the explosions of dying stars – supernova. Turns out supernovas write in radioactive ink called Iron-60.
As the Sun travels through the Galaxy, so too do the hundreds of billions of other stars that comprise the Milky Way; all swirling and spiraling in varying directions. If you could time travel to a distant past, you’d look up and see an unfamiliar sky – different stars, different constellations, and sometimes the glow of a brilliant supernova. Stars explode in the Milky Way about once every fifty years. Given the immense size of the Galaxy at around 150,000 light years in diameter, the odds of one of those stars exploding in our backyard is low. But while supernova happen in the Galaxy twice a century, those in close proximity to Earth, within 400 light years, do happen once every few million years. And along Earth’s epic 4.5 billion-year journey, it appears that we’ve had close encounters with supernova several times. In fact, we seem to be travelling through the fallout cloud of supernovae right now.Continue reading “The Solar System has been Flying Through the Debris of a Supernova for 33,000 Years”
The center of our very own galaxy might be one of the Universe’s most mysterious places. Astronomers have to probe through thick dust to see what’s going on there. All that dust makes life difficult for astronomers who are trying to understand all the radiation in the center of the Milky Way, and what exactly its source is.
A new study based on 20 years of data—and a hydrogen bubble where there shouldn’t be one—is helping astronomers understand all that energy.Continue reading “Astronomers See Through the Milky Way’s Dust to Track Where Radiation is Coming From at the Center of the Galaxy”
Over the years, scientific estimates of potential intelligent life in our galaxy have ranged widely. Some estimates say just one (only us Earthlings) to just a handful, to possibly thousands or even millions. A new study attempts to quantify the number of other worlds we could potentially talk to by estimating the number of intelligent civilizations within the Milky Way that are actively communicating.
The number?Continue reading “New Estimate Calculates There Could be 30 Intelligent Civilizations Communicating Across the Milky Way”