Astronomers Discover the Closest Known Black Hole

By -
https://www.smithsonianmag.com/science-nature/closest-black-hole-180974815/

Source:  By Megan Gannon, Smithsonian Magazine.

Excerpt: The pair of stars in a system called HR 6819 is so close to us that on a clear night in the Southern Hemisphere, a person might be able to spot them without a telescope. What that stargazer wouldn’t see, though, is the black hole hiding right there in the constellation Telescopium. At just 1,000 light-years away, it is the closest black hole to Earth ever discovered, and it could help scientists find the rest of the Milky Way's missing black holes. Dietrich Baade, an emeritus astronomer at the European Southern Observatory (ESO) in Germany and co-author of the study in Astronomy & Astrophysics, says the team never set out to find a black hole. They thought the HR 6819 system was a simple binary, made up of two visible stars orbiting each other. But their observations with the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile revealed something stranger: One of the stars orbited an unknown object every 40 days, while the second star revolved around this inner pair. ...the unseen object is more than four times the mass of our sun. An object so big yet invisible must be a black hole. ...the newfound black hole is not gathering mass from its companion star. Very few examples of this type of “non-interacting” black hole are known in the Milky Way, but this discovery could lead astronomers to reveal a hidden cosmic population. Astronomers have predicted that in our galaxy alone there should be 100 million to 1 billion black holes of stellar mass (meaning black holes that formed when stars collapsed under the influence of their own gravity). But so far they've only detected about two dozen of them. "That's one of the biggest discrepancies in astronomy," Baade says....  See also Astronomers find closest black hole to Earth, hiding in plain sight, By Daniel Clery, Science Magazine [https://www.sciencemag.org/news/2020/05/astronomers-find-closest-black-hole-earth-hiding-plain-sight]
________________________

Popular posts from this blog

Stellar remains of famed 1987 supernova found at last

By -
https://www.science.org/content/article/stellar-remains-famed-1987-supernova-found-last By DANIEL CLERY , Science.  Excerpt: When a nearby star exploded in 1987, it created the first supernova visible to the naked eye in 4 centuries and became one of the most intensely studied objects in space. Now, after more than 35 years of searching, researchers have finally discovered the cinder left behind. Using NASA’s new giant space telescope JWST, astronomers spotted  glowing gas at the center of the blast that can only have been energized by something hot and compact inside it , they report this week in Science. They believe a neutron star, all that remains of the shattered star, is responsible.... 
Read more

Planets around dead stars offer glimpse of the Solar System’s future—after the Sun swallows us up

By -
https://www.science.org/content/article/planets-around-dead-stars-offer-glimpse-solar-system-s-future-after-sun-swallows-us By JONATHAN O’CALLAGHAN , Science.  Excerpt: In about 5 billion years the Sun will balloon up into a red giant, consuming Mercury, probably Venus, and maybe even Earth. But even if the outer planets avoid being swallowed up, they might eventually get pulled in or ejected from the Solar System. A new discovery suggests they can survive intact. Using NASA’s JWST space telescope, astronomers have for the first time directly imaged planets on Solar System–like orbits around white dwarfs, the dead stars left after Sun-like stars swell into red giants and subside. The planets follow orbits resembling those of the giant planets in the outer Solar System—big enough for them to have escaped the inferno.... For GSS A Changing Cosmos chapter 1.
Read more

The Smallest Moon of Mars May Not Be What It Seemed

By -
https://www.nytimes.com/2023/04/25/science/mars-deimos-moon-photos.html By Jonathan O’Callaghan , The New York Times.  Excerpt: Deimos, the smaller of the two moons of Mars, might be a chip off the old block — quite literally. That’s the conclusion drawn by scientists in the United Arab Emirates, whose Hope orbiter — also called the Emirates Mars Mission and the country’s first interplanetary spacecraft — just snapped the best views of Deimos ever taken by human spacecraft. ... Mars has two irregularly shaped moons , and neither is mighty. Phobos, the larger of the two, is about 17 miles in diameter at its widest, and orbits closer to the red planet at an altitude of about 3,700 miles. Deimos is just nine miles across on its longest side, and completes an orbit of Mars every 30 hours at an altitude of 15,000 miles. The moons’ small size and quirky dimensions led to suggestions that they may be asteroids captured by Mars long ago. Not so, say researchers analyzing data recorded by Hope,
Read more