Science & Tech · Space · 10 hrs ago
Hubble evidence dates a major Milky Way merger to 11.8 billion years ago
Hubble observations point to an ancient collision that helped shape the young Milky Way about 11.8 billion years ago.
The Milky Way, our galaxy, grew partly by absorbing smaller galaxies, but the timing and identity of some early mergers were uncertain.
Researchers led by Davide Massari studied 39 globular clusters in the galaxy’s inner region, using their ages and chemical makeup as clues to their origins.
They found a group of clusters unlike those formed in the Milky Way or brought in by another known merger.
The clusters point to a dwarf galaxy called LKH that the Milky Way absorbed.
The researchers estimate LKH held about 500 million times the Sun’s mass in stars, a substantial share of the young Milky Way’s mass.
The finding pushes the known history of the Milky Way’s growth 1.8 billion years further back, and the study does not state what happens next.
Hubble observations provide evidence that the young Milky Way merged with a dwarf galaxy called LKH about 11.8 billion years ago.
The merger occurred roughly 2 billion years after the Big Bang, according to research published in Nature Astronomy.
Researchers identified a population of globular clusters that they say formed in LKH.
They estimate LKH contained about 500 million times the Sun’s mass in stars.
The finding pushes the known history of the Milky Way’s growth 1.8 billion years farther into the past.
- Who
- The Milky Way and a dwarf galaxy called LKH.
- What
- Hubble observations provided evidence of a merger between the galaxies.
- When
- About 11.8 billion years ago, roughly 2 billion years after the Big Bang.
- Where
- In the Milky Way; the study analyzed globular clusters in its inner 20,000 light-years.
- Why
- The merger contributed to the Milky Way’s growth. The sources do not state why the galaxies collided.
This story does not have two clearly opposing sides.
The young Milky Way merged with the dwarf galaxy LKH, according to the study.
The Milky Way consumed a galaxy called Gaia-Sausage-Enceladus.
The Sagittarius dwarf galaxy began merging with the Milky Way, and the process continues today.
- Merger date
- About 11.8 billion years ago
- Dwarf galaxy
- LKH
- LKH stellar mass
- Roughly 500 million times the Sun’s mass in stars
- Clusters studied
- 39 globular clusters
- Study region
- Inner 20,000 light-years of the Milky Way
- Research journal
- Nature Astronomy
What people are saying
Our home is the Milky Way galaxy, but we do not know how our house was built
In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH
Thanks to the high resolution and depth of Hubble imaging, we could measure the age and the metal content of these clusters with unprecedented precision