Astronomy

Contrary to a previous report, there’s no evidence of an intermediate-mass black hole in Omega Centauri, the Milky Way’s most massive and luminous globular star cluster, a new study finds. Instead, a hive of much smaller black holes diving into and out of the tightly packed star cluster’s center can explain the movement and distribution of its many ancient stars.

“What we found in our analysis is that the data favor an extended component [of stellar-mass black holes] as opposed to an intermediate-mass black hole,” says Andrés Bañares-Hernández, an astronomer at the Instituto de Astrofísica de Canarias in La Laguna, Spain. Some 10,000 to 20,000 stellar-mass black holes — adding up to between 200,000 and 300,000 times the mass of the sun — that are spread around the center of the star cluster can explain the observations, he says. More

One of the farthest known quasars seems to have shut down the creation of new stars in all the galaxies within its vicinity.

A quasar is a powerful source of light, created by torrid gas orbiting a gargantuan black hole at the center of a galaxy. The intense radiation from one quasar, named VIK J2348-3054, has probably stopped star formation at least 16 million light-years away from itself, astronomer Trystan Lambert and colleagues report in a paper to appear in Astronomy and Astrophysics. More

To leave a lasting trail, meteors need to aim low. A new survey of shooting stars shows that meteors that blaze through 90 kilometers up in the sky leave a persistent afterglow, unlike those that burn up at greater heights.

Meteors are normally blink-and-you’ll-miss-it events. A particle of space dust leaves a fiery trail of light as it zips through the atmosphere, and then it’s gone. But sometimes, a meteor leaves a lingering afterglow. Astronomers have noted these persistent trains for more than a century, but questions remained about their origins. More

The star marking true north is a good deal heavier than we thought.

The North Star is 5.1 times as massive as the sun, astronomers report in work submitted July 12 to arXiv.org. That value, calculated from the motion of a much fainter star that orbits the luminary, is nearly 50 percent heavier than a recent estimate of 3.45 solar masses.

Mass profoundly affects stellar life: The more mass a star has, the faster it burns its fuel and the sooner it dies. The earlier mass estimate had suggested that the North Star, also known as Polaris, is roughly 100 million years old (SN/12/2/16). The new estimate means the star formed more recently than this, but no one has yet calculated a revised age. More

For the first time, astronomers have spotted a middleweight black hole in the nearby universe. The discovery could help solve the riddle of how even heftier black holes form and grow up with their host galaxies.

The black hole, which sits about 16,000 light-years from Earth in the center of star cluster Omega Centauri, is at least 8,200 times as massive as the sun, putting it squarely in a rare category of intermediate-mass black holes, researchers report July 10 in Nature. More

Keep your eyes on the night sky this summer, scanning for the constellation Corona Borealis, and if you are lucky, you may glimpse what appears to be a new star winking on in the dark.

The brightening point of light will not be a new star, but a nova eruption about 3,000 light-years from Earth. There, a white dwarf star orbiting a red giant tears material from its larger companion. When enough mass collects on the white dwarf’s surface, the rising pressure and temperature will trigger a blast that can be seen from Earth with the naked eye — but for only a few days to a week. More

Supermassive black holes at the hearts of active galaxies may be churning out a lot of the universe’s high-energy neutrinos.

Two teams using data from IceCube, the world’s premier neutrino observatory located in Antarctica, have independently identified a common type of these active galaxies, called Seyfert galaxies, as likely neutrino producers. These findings, reported in Physical Review Letters and arXiv.org, bolster some astronomers’ view that the cores of such active galaxies could churn out the majority of the cosmic neutrinos seen streaming across the universe. More

Within the dusty cloud left behind by supernova 1987A, the most famous stellar explosion in modern history, astronomers have found compelling evidence for a long-sought neutron star.

NASA’s James Webb Space Telescope has spied indirect hints of a powerful source of X-rays — likely some type of neutron star — coming from the core of the supernova remnant, researchers report February 22 in Science. The findings are part of a 37-year-old quest to determine what happened in the aftermath of the closest supernova in nearly 400 years and could provide insights into how a neutron star behaves mere decades after its birth.

“Supernova 1987A is truly a unique laboratory to study supernovas,” astronomer Patrick Kavanagh said February 17 in a news conference at the American Association for the Advancement of Science meeting in Denver. It’s “the gift that keeps on giving, with new observations continually yielding new discoveries,” said Kavanagh, of Maynooth University in Ireland.

It’s rare for scientists to have observations of a giant star before it explodes in a supernova — but they got lucky with supernova 1987A. On the left is the blue supergiant before the explosion. On the right is the explosion itself.David Malin, AAT

On February 23, 1987, telescopes around the world got a front-row seat to a spectacular supernova in the Large Magellanic Cloud, a companion galaxy to the Milky Way (SN: 2/8/17). Such explosions occur when a star at least eight times the mass of the sun dies. Located at the astronomically close distance of 160,000 light-years, supernova 1987A, as it came to be known, was visible with the naked eye in the night sky for months afterward. The energetic explosion generated tremendous amounts of neutrinos, a handful of which ended up in detectors on Earth. It was the first time such ghostly particles had been seen coming from beyond the solar system.

Since then, scientists have wondered whether the iron core of the blue supergiant star that led to 1987A collapsed into an ultradense neutron star or shrank all the way down to a black hole. The fact that neutrinos escaped the event favors the neutron star possibility, but whatever was left behind has yet to be spotted. That’s partly because the original star’s outer layers, now traveling away from the explosion at 10,000 kilometers per second, create a thick haze of dust that obscures the area. More