Although neighboring Andromeda Galaxy may look tranquil, scientists are realizing the extent of its tumultuous history. After taking the widest survey yet of faint stars in Andromeda’s neighborhood, a team of astronomers led by Alan McConnachie at the NRC Herzberg Institute of Astrophysics in Victoria, British Columbia, discovered signs of ancient mergers and near-collisions with smaller galaxies, all of which helped shape the Andromeda we see today.

Check out some of the archaeological traces in Andromeda Galaxy in the recent Astro Bulletin below.

To learn about other recent astronomical discoveries, visit the Science Bulletins website.

Dwarf galaxies are small, weakly glowing cousins of typical galaxies. Astronomers long thought that little star formation took place in dwarf galaxies, but a new analysis of images from the Hubble Space Telescope turns this assumption around.

To learn about other recent astronomical discoveries, visit the Science Bulletins website.

To understand how the modern Universe came to be, astronomers turn to computer models, programs that follow the physical laws of the Universe. Computer models can be run backward to reconstruct the past or forward to predict the future. A team of researchers from the Institute for Computational Cosmology at Durham University in the UK recently used computer models to simulate how the Universe’s big galaxies have changed over billions of years.

Their starting point was 500 million years after the Big Bang. At this time, big star-forming galaxies built up from gas that was clumping along filaments of dark matter, an invisible substance that pervades the Universe. The galaxies coalesced at dense points of dark matter where its gravity was strongly attractive. The team let the dark matter and the galaxies in the model evolve to the present day. The computational effort required both the Millenium Simulation, a simulation of how structures grow in dark matter, and a computer model that mimics how normal matter, such as gas, behaves.

The results showed that galaxies were at their peak of star formation somewhere between 2 billion and 3 billion years after the Big Bang, and have tapered off in modern times. Today, galaxies are far less active because most of their gas is already locked up in stars. Now, researchers can compare the computer model’s results with modern telescope maps of the Universe, such as those from VISTA, a new sky survey telescope at Chile’s Paranal Observatory. These comparisons can help the team gauge the accuracy of their galactic time machine.

To learn about other recent astronomical discoveries, visit the Science Bulletins website.