star formation tagged posts

A new model explains the exceptions to the galaxy main model sequence

The more massive, or full of stars, a galaxy is, the faster the stars in it are formed. This seems to be the general rule, which is contradicted, however, by some abnormal cases, for example thin (not massive) galaxies that are hyperactive in their star formation. Until now the phenomenon had been explained by catastrophic external events like galaxies colliding and merging, but a new theory offers an alternative explanation, related to an in situ (internal) process of galaxy evolution. The new theory correctly reproduces the behaviour of both normal and abnormal (or outlier) galaxies, and may be further tested by new observations.

If we put the galaxies for which we have the relevant data into a graph relating the mass ...

A deep photographic image of M83 taken using the UK Schmidt Telescope by Malin & Hadley (1997, figure reproduced with permission) where the white scale bar corresponds to 30 arcmin. The northern stream appears not to be associated with dw1335-29, circled in red. Credit: Carrillo et al., 2016.

M83, Southern Pinwheel Galaxy has a newly found dwarf satellite 85,000 light years from its host. This satellite galaxy was designated dw1335-29 and could be an irregular or a transition dwarf. Messier 83 is one of the closest and brightest barred spiral galaxies. It is located about 15 million light years away in the constellation Hydra. Finding new satellites of galaxies beyond the Local Group such as Messier 83 could provide essential insights on galaxy formation in a cosmological context.

In 2015,...

A Hubble image of a field of distant galaxies. A new study of the gas content in galaxies so distant their light has been traveling for about ten billion years suggests that the processes converting gas into stars is about the same back then as in the local universe. NASA, ESA, G. Illingworth (UCO/Lick & UCSC), R. Bouwens (UCO/Lick & Leiden U.), and the HUDF09 Team

The first stars appeared ~100 million years after the big bang, and ever since then stars and star formation processes have lit up the cosmos. When the universe was about 3 billion years old, star formation activity peaked at rates about 10 times above current levels...

An artist’s impression shows a very distant quasar powered by a black hole with a mass two billion times that of the Sun. CREDIT: ESO/M. KORNMESSER

Astronomers have linked extremely reddened quasars to strong galactic outflowing winds that inhibit star formation in the early universe. Galaxies formed and grew billions of years ago by accumulating gas from their surroundings, or colliding and merging with other young galaxies. These early stages of galaxy assembly are believed to be accompanied by episodes of rapid star formation, known as starbursts, and rapid growth of a single super-massive black hole in the galactic centers.

A popular paradigm for this evolution has the black holes growing mostly in obscurity, buried deep within the dusty gas...