NAOJ: Planets Around a Black Hole?

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bystander
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NAOJ: Planets Around a Black Hole?

Post by bystander » Wed Nov 27, 2019 11:53 pm

Planets Around a Black Hole? Calculations Show Possibility of Bizarre Worlds
National Astronomical Observatory of Japan | Center for Computational Astrophysics | 2019 Nov 25
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun. They proposed the possibility of thousands of planets around a supermassive black hole. ...

According to the latest theories, planets are formed from fluffy dust aggregates in a protoplanetary disk around a young star. But young stars are not the only objects that possess dust disks. In a novel approach, the researchers focused on heavy disks around supermassive black holes in the nuclei of galaxies. ...

Some supermassive black holes have large amounts of matter around them in the form of a heavy, dense disk. A disk can contain as much as a hundred thousand times the mass of the Sun worth of dust. This is a billion times the dust mass of a protoplanetary disk.

In a low temperature region of a protoplanetary disk, dust grains with ice mantles stick together and evolve into fluffy aggregates. A dust disk around a black hole is so dense that the intense radiation from the central region is blocked and low temperature regions are formed. The researchers applied the planet formation theory to circumnuclear disks and found that planets could be formed in several hundred million years. ...

Planet Formation around Supermassive Black Holes in Active Galactic Nuclei ~ Keiichi Wada, Yusuke Tsukamoto, Eiichiro Kokubo
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BDanielMayfield
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Re: NAOJ: Planets Around a Black Hole?

Post by BDanielMayfield » Fri Nov 29, 2019 4:00 pm

It does make sense that planets could form in the cold outer reaches of AGN SMBHs. (That is, in the dust bands surrounding them.) Here's the abstract from the paper suggesting this:
As a natural consequence of the elementary processes of dust growth, we discovered that a new class of planets can be formed around supermassive black holes (SMBHs). We investigated a growth path from sub-micron sized icy dust monomers to Earth-sized bodies outside the "snow line", located several parsecs from SMBHs in low luminosity active galactic nuclei (AGNs). In contrast to protoplanetary disks, the "radial drift barrier" does not prevent the formation of planetesimals. In the early phase of the evolution, low collision velocity between dust particles promotes sticking; therefore, the internal density of the dust aggregates decreases with growth. When the porous aggregate's size reaches 0.1--1 cm, the collisional compression becomes effective, and the decrease in internal density stops. Once 10--100 m sized aggregates are formed, they are decoupled from gas turbulence, and the aggregate layer becomes gravitationally unstable, leading to the formation of planets by the fragmentation of the layer, with ten times the mass of the earth. The growth time scale depends on the turbulent strength of the circumnuclear disk and the black hole mass MBH, and it is comparable to the AGN's lifetime (∼10^8 yr) for low mass (MBH∼10^6M⊙) SMBHs.
I'm wondering now about the frequency of this type of planet. Are they common in galaxies like ours, and what about their longevity?

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Re: NAOJ: Planets Around a Black Hole?

Post by neufer » Fri Nov 29, 2019 5:54 pm

BDanielMayfield wrote:
Fri Nov 29, 2019 4:00 pm

It does make sense that planets could form in the cold outer reaches of AGN SMBHs. (That is, in the dust bands surrounding them.)

I'm wondering now about the frequency of this type of planet. Are they common in galaxies like ours, and what about their longevity?
Hopefully, they are common, long lived & habitable.

We are approaching the mid-21st century and hurricanes, flooding, crop blights and dust storms are threatening humanity's survival. The world has become a post-truth society where the older [Fox News] generation is teaching that scientific climatology is faked in order to discourage actual investment in the future and other “excesses of the twentieth century.”
https://en.wikipedia.org/wiki/Interstellar_(film) wrote:
<<In the mid-21st century, crop blights and dust storms threaten humanity's survival, with corn the only remaining viable crop. The world has become a post-truth society where younger generations are taught that scientific breakthroughs such as the Apollo moon missions were faked, to discourage interest in space travel and other “excesses of the twentieth century.”

Professor Brand reveals that 48 years earlier, unknown beings positioned a wormhole near Saturn, opening a path to a distant galaxy with twelve potentially habitable worlds located near a black hole named Gargantua. Twelve volunteers traveled through the wormhole, each to survey a different planet, and three of them – Miller, Edmunds, and Mann – reported positive results. Based on their data, Professor Brand conceived two plans to ensure humanity's survival. Plan A involves developing a gravitational propulsion theory to facilitate a mass exodus, while Plan B involves launching the Endurance spacecraft through the wormhole with 5,000 frozen human embryos to colonize a habitable planet.>>
Art Neuendorffer