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Old 10-07-2020, 11:44 AM
gary
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Question Is Planet Nine a grapefruit-sized black hole in our Solar System? Search is on.

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Originally Posted by Harvard & Smithsonian Center for Astrophysics, Thursday, July 9, 2020
Cambridge, MA -
Scientists at Harvard University and the Black Hole Initiative (BHI) have developed a new method to find black holes in the outer solar system, and along with it, determine once-and-for-all the true nature of the hypothesized Planet Nine. The paper, accepted to The Astrophysical Journal Letters, highlights the ability of the future Legacy Survey of Space and Time (LSST) mission to observe accretion flares, the presence of which could prove or rule out Planet Nine as a black hole.

Dr. Avi Loeb, Frank B. Baird Jr. Professor of Science at Harvard, and Amir Siraj, a Harvard undergraduate student, have developed the new method to search for black holes in the outer solar system, based on flares that result from the disruption of intercepted comets. The study suggests that the LSST has the capability to find black holes by observing for accretion flares resulting from the impact of small Oort cloud objects.

"In the vicinity of a black hole, small bodies that approach it will melt as a result of heating from the background accretion of gas from the interstellar medium onto the black hole," said Siraj. "Once they melt, the small bodies are subject to tidal disruption by the black hole, followed by accretion from the tidally disrupted body onto the black hole." Loeb added, "Because black holes are intrinsically dark, the radiation that matter emits on its way to the mouth of the black hole is our only way to illuminate this dark environment."

Future searches for primordial black holes could be informed by the new calculation. "This method can detect or rule out trapped planet-mass black holes out to the edge of the Oort cloud, or about a hundred thousand astronomical units," said Siraj. "It could be capable of placing new limits on the fraction of dark matter contained in primordial black holes."
Quote:
Originally Posted by Harvard & Smithsonian Center for Astrophysics
"Planet Nine is a compelling explanation for the observed clustering of some objects beyond the orbit of Neptune. If the existence of Planet Nine is confirmed through a direct electromagnetic search, it will be the first detection of a new planet in the solar system in two centuries, not counting Pluto, said Siraj, adding that a failure to detect light from Planet Nine—or other recent models, such as the suggestion to send probes to measure gravitational influence—would make the black hole model intriguing. "There has been a great deal of speculation concerning alternative explanations for the anomalous orbits observed in the outer solar system. One of the ideas put forth was the possibility that Planet Nine could be a grapefruit-sized black hole with a mass of five to ten times that of the Earth."
Full press release here :-
https://www.cfa.harvard.edu/news/2020-13
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Old 10-07-2020, 12:08 PM
glend (Glen)
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I always believed you needed a certain mass to develop a black hole. A grapefruit sized black hole? Sounds impossible.
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Old 10-07-2020, 05:19 PM
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Atmos (Colin)
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Quote:
Originally Posted by glend View Post
I always believed you needed a certain mass to develop a black hole. A grapefruit sized black hole? Sounds impossible.
There is a theory that there are primordial black holes scattered throughout the cosmos. Usually these micro black holes are typically expected to be much much much smaller and have been used as a way of defining dark matter; although not a widely accepted hypothesis.

Planetary mass black holes could theoretically have been “normal” garden variety ones back 13 billion years ago and reduced in size due to Hawking radiation over the eons.
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Old 10-07-2020, 06:26 PM
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Quote:
Originally Posted by glend View Post
I always believed you needed a certain mass to develop a black hole. A grapefruit sized black hole? Sounds impossible.
The Swarzchild radius is dependent on radius and mass not amount of mass. Any amount of mass if compressed into a small enough sphere will form a black hole.

I think
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Old 10-07-2020, 06:42 PM
gary
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Quote:
Originally Posted by glend View Post
I always believed you needed a certain mass to develop a black hole. A grapefruit sized black hole? Sounds impossible.
Hi Glen,

Hypothesised primordial black holes are remnant bits of matter that
collapsed back in on themselves shortly after the Big Bang.

See
https://en.wikipedia.org/wiki/Primor...0black%20holes.

They had at one point been a Dark Matter candidate but a Japanese
research group claimed last year they had proven they can't :-
https://www.universetoday.com/141923...l-black-holes/
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