Astronomers Discover More Mini-Galaxies Around the Milky Way

Share:

Astronomers have recently found two new dwarf galaxy candidates orbiting our Milky Way galaxy.

These discoveries suggest there could be up to 500 similar small galaxies surrounding the Milky Way, which is more than double what was previously estimated.

The new potential dwarf galaxies, named Sextans II and Virgo III, were spotted using the Hyper Suprime-Cam (HSC) attached to Japan’s Subaru Telescope.

These tiny galaxies are about 411,000 and 492,000 light-years away from Earth, respectively.

They are likely ultra-compact dwarf galaxies (UCDs), which are clusters of old stars packed closely together, making them brighter than other small galaxies.

What Are Satellite Galaxies?

A satellite galaxy is a group of stars that orbits around the Milky Way independently.

The largest known satellite galaxy is the Large Magellanic Cloud, which contains about 30 billion stars and can be seen with the naked eye.

Other known satellite galaxies are much smaller, with only a few hundred thousand or a couple of million stars.

Current Estimates and Challenges

In 2020, scientists estimated there were around 60 known satellite galaxies orbiting the Milky Way.

However, there is still some uncertainty because scientists disagree on the size and distance from the galactic center that these star clusters need to be to count as true satellite galaxies.

Most astronomers believe there are many more unknown satellite galaxies out there.

Based on our understanding of dark matter — which makes up about 27% of the universe’s mass and interacts gravitationally with visible matter — researchers have long thought that the Milky Way should have around 220 satellite galaxies.

The fact that we haven’t found as many as expected is known as the “missing satellites problem.”

A New Problem: Too Many Satellites?

The new study, published on June 8 in the Publications of the Astronomical Society of Japan, revealed the two new satellite galaxies.

Instead of solving the “missing satellites problem,” the location and orientation of these new discoveries suggest there are even more satellite galaxies than previously thought.

This has introduced a new issue, which researchers are calling the “too many satellites problem.”

Conclusion

The discovery of Sextans II and Virgo III hints that many more mini-galaxies could surround our galaxy than we realized.

This challenges our current understanding of the Milky Way’s structure and the distribution of dark matter in our galaxy.

The search for these hidden galaxies continues, promising more exciting discoveries in the future.


Share: