Category Astronomy/Space

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 ...

Images: This pair of drawings depicts the same location on Mars at two points in time: now and billions of years ago. The location is in Gale Crater, near the Red Planet’s equator. 1 shows a present-day snapshot of the northern half of Gale Crater. North is to the left. The underlying basement is the crust of Mars that forms the crater’s rim (left) and central peak (right). About 3.5 billion years ago, rivers brought sediment into the crater, depositing pebbles where the river was flowing more quickly, sand where the river entered a standing body of water in the center of the basin, and silt within this lake. Lake level rose over time as the sediments built up. Eventually they were buried by dry dust...

Artist’s impression of the planet orbiting the red dwarf star Proxima Centauri. Credit: ESO

Dimitra Atri, an astrobiologist with the Blue Marble Institute of Space Science, has run simulations of planet Proxima b, an exoplanet circling the star Proxima Centauri, which could possibly support life. Last August, a team of scientists identified a planet circling Proxima Centauri—at 4.2 light-years away, the red dwarf is the closet star to our own sun and the discovery of a planet in its Goldilocks zone excited the astronomy community because it represented the possibility extraterrestrial life. Since that time, Atri has created and run simulations meant to measure the impact of stellar flares on the planet and whether they might be enough to prevent or allow life to exist on the planet.

Pr...

An artist’s depiction of a rapidly spinning supermassive black hole surrounded the rotating leftovers of a star that was ripped apart by the tidal forces of the black hole. Credit: ESO, ESA/Hubble, M. Kornmesser

Astronomers illuminate the role rapidly spinning black holes play in tidal disruption events. Back in 2015 when astronomers discovered an intense flare in a distant galaxy, they considered it the brightest supernova ever observed. Now, UC Santa Barbara astrophysicists and a group of international colleagues offer an entirely different interpretation based on new astronomical observation data from the Las Cumbres Observatory (LCO), a global robotic telescope network, and the Hubble Space Telescope.

The new information indicates that the event, called ASASSN-15lh, is actually a tidal...