Astronomers have found the strongest evidence yet that the formation of massive stars follows a path similar to their lower-mass brethren — but on steroids! The new findings show that the episodic explosive outbursts within what are called accretion discs, known to occur during the formation of average mass stars like our Sun, also happen in the formation of much more massive stars.
Some galaxies pump out vast amounts of energy from a very small volume of space, typically not much bigger than our own solar system. The cores of so-called active galactic nuclei (AGNs) can be billions of light-years away, so are difficult to study in any detail. However, natural gravitational ‘microlenses’ can provide a way to probe these objects.
A team of Spanish astrophysicists has obtained precise measurements for the innermost region of a disc of matter in orbital motion around a supermassive black hole in the lensed quasar known as Einstein’s Cross (Q2237-0305). It constitutes the most precise set of measurements achieved to date for such a small and distant object.
When a star comes too close to the intense gravity of black hole, the resulting tidal forces can rip the star apart. In these so-called tidal disruptions, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole, causing a distinct X-ray flare that can last for years. A team of astronomers has observed a tidal disruption event in galaxy PGC 043234 that lies about 290 million light-years from Earth.