Exactly How Massive is the Milky Way? - by BrianKoberlein
Globular clusters are bright dense clusters of stars. Since stars within a globular cluster are gravitationally bound, these clusters move around the galaxy like a single object. They are found in a sphere surrounding the Milky Way, so measuring their motion helps us measure the mass of the galactic halo.To measure the outer region of the galactic halo, we can look at the motion of satellite galaxies such as the Magellanic Clouds. There are about 60 small galaxies within about 1.
All of these approaches calculate the mass of the Milky Way from orbital motion. There are a few methods that don’t rely on the orbital motion. One of these is to look at the tidal plumes of dwarf galaxies. In the history of our galaxy, there are some globular clusters and dwarf galaxies that strayed too close to the central region of the Milky Way and were ripped apart by tidal forces. The remnants of these galaxies form a stream of stars, such as the Sagittarius stream.
Another approach is to look at stars leaving our galaxy. Occasionally a star will have a near miss with another star and gain enough velocity to escape our galaxy. Since the escape velocity depends on galactic mass, a statistical measure of escaping stars gives a mass for the galaxy. Finally, we can look at the local group of galaxies. This includes the Andromeda galaxy and its satellite galaxies. Our local group is gravitationally isolated from more distant galaxy clusters, so looking at the equilibrium state of the local group gives us a handle on its overall mass and the mass of the Milky Way.
Each of these approaches has its own advantages and levels of accuracy. None of them are the final say on their own. In this latest work, the team took a statistical average of various methods and derived what we might call the best value for the mass of our galaxy. The value they determined was a trillion solar masses, give or take a few hundred billion solar masses.
United States Latest News, United States Headlines
Similar News:You can also read news stories similar to this one that we have collected from other news sources.
15 Incredible Photos from 2023 Milky Way Photographer of the YearThe winners of the 2023 Milky Way Photographer of the Year competition are absolutely breathtaking.
Read more »
Galactic Bubbles: Unexpected Complexity of the Milky Way’s Mysterious StructuresFresh look at old data reveals novel details about galactic formation. Astronomers have found that eRosita bubbles, high-energy gas structures in the Milky Way, are more complex and not hotter than surrounding areas, contrary to previous assumptions. Their analysis of Suzaku satellite data suggests
Read more »
A Guide to Hiking for Anyone Who’s Not Exactly OutdoorsyEverything you need to know to have a good time—and stay safe—on the trails.
Read more »
Exactly How to Maximize the Benefits of Walking While You WorkBecause you need to move more throughout the day—not just on a run.
Read more »
Weekly Horoscope: Time to Manifest Your Wildest DreamsThe cosmic energy is giving us exactly what we need.
Read more »
Our World Is Going Full ‘Black Mirror’The world of Black Mirror seems nearer than ever to our current reality—less a warning than a crystal ball. (From 2016)
Read more »