Astronomy

NATIONAL HARBOR, MD. — A bright blip in a distant galaxy may link two mysterious categories of cosmic flares. The event, which astronomers playfully call the Platypus, could also offer a new way to understand the origins of supermassive black holes that reside at the centers of most galaxies.

The brilliant burst, spotted in a dwarf galaxy about 6.5 billion light-years from Earth, has many of the hallmarks of a tidal disruption event, the final flash of a star being ripped apart by a black hole. But it also resembles another type of flash, dubbed an LFBOT, which astronomers think might be a class of exploding star. More

The Milky Way keeps its planets close to its chest. Stars in a thin, flat disk bisecting the galaxy have more planets on average than stars in a thicker, enveloping disk — and astronomers now think they know why.

Stars that currently live in the galaxy’s thick disk were born during a time of galactic chaos, says MIT astrophysicist Tim Hallatt. The stars’ violent upbringing hindered their ability to grow and retain planets, he and astrophysicist Eve Lee, formerly of McGill University in Montreal, report January 22 in the Astrophysical Journal. More

BOSTON — For the first time, astronomers have detected an astrosphere around a star like the sun.

This bubble of hot gas is blown by a star’s stellar wind, a constant stream of charged particles every star emits. The sun’s version of this bubble, called the heliosphere, marks the edge of our solar system and protects the planets from most of the high-energy cosmic rays that zip about the galaxy (SN: 12/10/18, SN: 10/15/09).

Astronomers have seen analogous bubbles around hot stars, dying stars and baby stars — but not sunlike stars. More

For the first time, scientists have captured a zoomed-in photo of a star outside of our Milky Way galaxy. The image revealed surprising details about WOH G64, a giant star that is probably dying, researchers report November 21 in Astronomy & Astrophysics.

The star, which is about 1,500 times the size of our sun, sits 160,000 light-years away from Earth. It lives inside the Large Magellanic Cloud, a small galaxy that orbits the Milky Way. More

A colossal census of the cosmos has more than tripled the number of active black holes known to reside in miniature galaxies and found the biggest haul of middleweight black holes to date.

The survey turned up about 2,500 dwarf galaxies with actively feeding black holes at their centers, up from about 500 known before, researchers report in a paper submitted October 31 to arXiv.org. The team also found nearly 300 new intermediate-mass black hole candidates, an increase from about 70 previous possible detections (SN: 9/2/20). More

Some massive stars may go out with a fizzle, not a bang.

A star that winked out of view could be a “failed supernova,” a stellar explosion that petered out instead of fully detonating, a new study reports. If real, the failed supernova would mark the birth of a black hole.

At the ends of their lives, massive stars explode in dazzling outbursts known as supernovas, kicked off when the star’s core collapses. But sometimes, scientists suspect, there’s not enough oomph for a full explosion, resulting in a star that switches off without fireworks.  More

Some 6,500 light-years from Earth lurks a zombie star cloaked in long tendrils of hot sulfur.

Nobody knows how those tendrils formed. But astronomers now know where they’re going. New observations, reported in the Nov. 1 Astrophysical Journal Letters, capture the 3-D structure and motion of debris left in the wake of a supernova that was seen to detonate almost 900 years ago.

“It’s a piece of the puzzle towards understanding this very bizarre [supernova] remnant,” says astronomer Tim Cunningham of the Harvard & Smithsonian Center for Astrophysics in Cambridge, Mass. More

Dozens of fugitive stars were caught fleeing a dense star cluster in a satellite galaxy of the Milky Way. The swarm of speeding stars could mean that such runaways had a bigger influence on cosmic evolution than previously thought, astronomers report October 9 in Nature.

Massive stars are born in young clusters, packed so close together that they can jostle each other out of place. Sometimes, encounters between pairs of massive stars or neighboring supernova explosions can send a star zipping out of the cluster altogether, to seek its fortune in the wider galaxy and beyond. More