Australian astronomers have discovered what makes some spiral galaxies fat and bulging while others are flat discs — and it’s all about how fast they spin.
The Astrophysical Journal
The research, led by the International Centre for Radio Astronomy Research (ICRAR) in Perth, found that fast-rotating spiral galaxies are flat and thin while equally sized galaxies that rotate slowly are fatter.
The study was published today in the prestigious Astrophysical Journal and was part of “The Evolving Universe” research theme of the ARC Center of Excellence for All-sky Astrophysics (CAASTRO).
ICRAR Research Associate Professor Danail Obreschkow, from The University of Western Australia, said it is a much-debated mystery why galaxies look so different to each other.
“Some galaxies are very flat discs of stars and others are more bulging or even spherical,” he said.
The Andromeda Galaxy is surrounded by a swarm of small satellite galaxies. Researchers from the Niels Bohr Institute, among others, have detected a stream of stars in one of the Andromeda Galaxy’s outer satellite galaxies, a dwarf galaxy called Andromeda II. The movement of the stars tells us that what we are observing is the remnant of a merger between two dwarf galaxies. Mergers between galaxies of such low mass has not been observed before. The results are published in the scientific journal Nature.
The galaxies in the early universe started off small and the theory of the astronomers is that the baby galaxies gradually grew larger and more massive by constantly colliding with neighboring galaxies to form new, larger galaxies. Large, massive galaxies constantly attract smaller galaxies due to gravity and they eventually merge together and grow even larger.
Astronomers have reported the discovery of one of the most distant galaxies, dubbed Abell2744 Y1.
Astronomy and Astrophysics Letters
Four unknown galaxy clusters each potentially containing thousands of individual galaxies have been discovered some 10 billion light-years from Earth.
An international team of astronomers, led by Imperial College London, used a new way of combining data from the two European Space Agency satellites, Planck and Herschel, to identify more distant galaxy clusters than has previously been possible. The researchers believe up to 2,000 further clusters could be identified using this technique, helping to build a more detailed timeline of how clusters are formed.
Astronomer has seen the river of hydrogen flowing through space with the help of NSF’s Robert C. Byrd Green Bank Telescope (GBT). Read more…