SPACE — The Milky Way Galaxy is the galaxy where Earth is located. Part of the Milky Way galaxy can be seen on a clear night as a thick cloud of stars and dust stretching across the sky.
We can see thousands of these stars with the naked eye. But how many stars are in the Milky Way?
“This is a very difficult question to answer,” said David Kornreich, an assistant professor at Ithaca College in New York, according to an article in Space.com.
Astronomers know that the Milky Way is a barred spiral galaxy that is about 100,000 light years across. When viewed from outside the galaxy, the Milky Way appears surrounded by four spiral arms.
Two large spiral arms and two small spiral arms. The main arms of the Milky Way are known as Perseus and Sagittarius. Earth’s sun is located in one of two small spiral arms called the Orion Arms.
How to measure the approximate number of stars
The galaxy is surrounded by a huge halo of hot gas several hundred thousand light years in diameter. Astronomers estimate that the mass of this halo is almost the same as the mass of all the stars in the Milky Way. However, many stars in the Milky Way are difficult to see.
This is because the center of the galaxy has a galactic bulge filled with stars, gas and dust as well as supermassive black holes. Objects in this region are so dense that even the most sophisticated telescopes cannot see them.
Astronomers used to think that all the stars in the universe were part of the Milky Way. However, that changed in the 1920s when Edwin Hubble succeeded in calculating the distance of the Andromeda nebula (now known as the Andromeda galaxy). He felt the distance was too far to be part of the Milky Way.
The main way astronomers estimate the number of stars in a galaxy is by determining the mass of the galaxy. Once the mass of a galaxy is determined, next, scientists find out how much mass it consists of stars.
For your information, most of the galaxy’s mass consists of dark matter, a type of material that does not emit light but is believed to make up most of the mass of the universe.
“You have to model the galaxy and see if you can understand what percentage of the mass the stars are. “In general galaxies, if you measure their mass by looking at the rotation curve, about 90 percent of it is dark matter,” Kornreich said.
Because most of the remaining matter in the galaxy consists of scattered gas and dust, Kornreich estimates that about 3 percent of the galaxy’s mass consists of stars.
However, this figure can vary. The size of the star can also vary greatly, from the size of our sun, to tens of times smaller or larger.
2023-11-26 14:24:00
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