There is a new record-closest black hole to us, and the world is taking notice. This was only put out yesterday, but newspapers and the Internet have lit up over a totally dark object that no one can see. However, it turns out that we don't have to see it to know that it is there and start studying it seriously. And then to go looking for lots more like it.
Scientists Find Nearest-Known Black Hole, In Distressingly Fitting Metaphor — NPR
If it feels as if gravity has been tugging harder than it usually does the past couple of months, it'd be easy to guess why — what with the global pandemic, a hemorrhaging economy and the strain of staying at least six feet away from just about everyone.
So perhaps it's an appropriate time to add news of another impossibly dark, heavy item to the list.
Hey, cut that out. This is physics. Fact-based reality, not Cloud-Cuckoo-Land clickbait.
Ooooooh, talk nerdy to me!
Abstract
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d binary consisting of a B3 III star and an unseen companion in a circular orbit. The radial-velocity semi-amplitude of 61.3 km s−1 of the inner star and its minimum (probable) mass of 5.0 M⊙ (6.3 ± 0.7 M⊙) imply a mass of the unseen object of ≥4.2 M⊙ (≥5.0 ± 0.4 M⊙), that is, a black hole (BH).
The spectroscopic time series is stunningly similar to observations of LB-1. A similar triple-star architecture of LB-1 would reduce the mass of the BH in LB-1 from ∼70 M⊙ to a level more typical of Galactic stellar remnant BHs. The BH in HR 6819 probably is the closest known BH to the Sun, and together with LB-1, suggests a population of quiet BHs. Its embedment in a hierarchical triple structure may be of interest for models of merging double BHs or BH + neutron star binaries.
The authors dedicate this Letter to the memory of Stan Štefl (1955−2014) in sadness and grateful appreciation of his never-tiring alertness that also triggered this work.
This Black Hole is Just 1000 Light Years Away From Earth, The Closest One Known as Yet
When the team began its research, astronomers weren't searching for a black hole. Instead, they were interested in studying double-star systems, and were shocked when a third, previously undiscovered body was spotted within HR 6819 — making it a triple-star system.
Unlike most black holes, which can be spotted when they violently interact with their environment, the unique one found in HR 6819 appears truly black, making it completely invisible. The team was only able to detect and research it by studying the warped 40-day orbit of one of its companion stars.
Astronomers find new black hole close to Earth
When astronomers observed the star system, in the Telescopium constellation, they noticed that one of the stars was completing an orbit around a hidden object every 40 Earth days. The second star is further out from the first star and the black hole.
The observation was made using the MPG/ESO 2.2-meter telescope at the European Southern Observatory’s La Silla Observatory in Chile.
Closest black hole to Earth discovered 1,000 light-years away.
Scientists stumbled upon the out-of-this-world discovery in the Telescopium constellation while tracking two stars orbiting each other just outside the gravitational pull of the black hole, with the help of a super telescope at the European Southern Observatory's La Silla Observatory in Chile.
Over the years, astronomers have found a couple dozen black holes in our Milky Way galaxy. They announce their presence by having disruptive, violent interactions with their surroundings and releasing detectable X-rays.
Normally, black holes are discovered from the way they interact violently with an accreting disc of gas and dust. As they shred this material, copious X-rays are emitted. It's this high-energy signal that telescopes detect, not the black hole itself.
So this is an unusual case, in that it's the motions of the stars, together known as HR 6819, that have given the game away.
Time Magazine
The previous closest black hole is probably about three times further, about 3,200 light-years, [ESO astronomer Thomas Rivinius] said.
“It will motivate additional searches among bright, relatively nearby stars,” said Ohio State University astronomer Todd Thompson, who wasn’t part of the research.
Like most of these type of black holes, this one is tiny, maybe 25 miles (40 kilometers) in diameter.
National Geographic
The team found evidence for the invisible object by tracking its two companion stars using the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile. They say this system could just be the tip of the iceberg, as many more similar black holes could be found in the future.
Closest black hole to Earth found 'hiding in plain sight'
May 6, 2020 — During winter in the Southern Hemisphere, a blue point of light in the constellation Telescopium gleams overhead. The brilliant pinprick on the sky, which looks like a bright star, is actually two stars in close orbit—accompanied by the closest known black hole to Earth.
Black hole found 1,000 light years from Earth | Science | The Guardian
19 hours ago - Object found in HR 6819 system is the closest to Earth yet known – and is unusually dark.
The system appears through a telescope as a single bright star, but telltale signs in the light emitted have previously revealed there to be two stars present.
Now experts say they have further analysed the data to discover there is another body within the system: a black hole with a mass over four times that of our sun, and the closest to Earth found so far.
One of the stars is moving periodically, with a period of 40 days. And the only way to understand that period and the very large [velocity] of 60km per second with a mass five times that of the sun was to infer that there is another very massive body which, however, is not visible.
19 hours ago — Astronomers discovered this black hole while studying what they thought was just a
binary star system, or two stars that orbit a common center of mass. They were using the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile to observe the binary, known as HR 6819, as part of a broader study on double star systems. When they analyzed their observations, the researchers were shocked to learn that a third object was hiding in the system: a black hole.
Astronomers say they've found the closest black hole to Earth … — The Verge
17 hours ago — Finding a black hole so close to Earth means that there might be even more tiny black holes peppered throughout the Universe — and even our own galaxy. “We only know of a few dozen black holes, but we suspect there might be a billion in the galaxy,” says Rivinius. “The fact that it’s so close actually means that it cannot be very uncommon.”
In Other Black Hole News
Astronomers have long studied supermassive black holes and smaller black holes that form when massive stars implode, but they have searched for intermediate-mass black holes for years.
Now, thanks to observations by the Hubble Space Telescope, astronomers have found their "missing link" to understand how black holes evolve. They were able to confirm the observation of an intermediate-mass black hole, known as an IMBH, inside a dense cluster of stars. This particular black hole is more than 50,000 times the mass of our sun.
Hubble Finds Best Evidence for Elusive Mid-Sized Black Hole — NASA
Mar 31, 2020 — Hubble was pointed at the X-ray source to resolve its precise location. Deep, high-resolution imaging provides strong evidence that the X-rays emanated not from an isolated source in our galaxy, but instead in a distant, dense star cluster on the outskirts of another galaxy — just the type of place astronomers expected to find an IMBH. Previous Hubble research has shown that the mass of a black hole in the center of a galaxy is proportional to that host galaxy's central bulge. In other words, the more massive the galaxy, the more massive its black hole. Therefore, the star cluster that is home to 3XMM J215022.4−055108 may be the stripped-down core of a lower-mass dwarf galaxy that has been gravitationally and tidally disrupted by its close interactions with its current larger galaxy host.
22 hours ago - Astronomers found an intermediate black hole — not too big, not too small — that sheds light on how the universe was assembled in the dark.