Brown Dwarf Objects as possible site for O'Neill Habitat

tahanson43206 · 2023-03-29 08:12:05

In another topic recently, the subject of gravitational confinement for fusion came up, in the context of Inertial Confinement.

This topic is offered for discussion of Brown Dwarf objects.

In the transcript in Post #2 of this topic, ChatGPT provides an overview of the subject, including a warning that even though Brown Dwarf objects may not produce high energy particles themselves, they can accelerate ions in their vicinity to high energy levels.

In pursuing this inquiry, I was hoping that a Brown Dwarf might be a suitable location for an O'Neill Habitat, because a Brown Dwarf is unlikely to explode as might be the case with a star that has achieved fusion.

It appears that the environment near a Brown Dwarf object might be hazardous.

(th)

tahanson43206 · 2023-03-29 08:14:17

Below is a transcript of a session with ChatGPT about Brown Dwarf objects.

Hello Again! Today I'd like to consider a different topic than those we've been working on. Given that Brown Dwarf objects may not have achieved fusion, what are the conditions that allow them to be observed by humans?

Brown dwarfs are substellar objects that are often referred to as "failed stars" because they are not massive enough to sustain nuclear fusion reactions in their cores, like normal stars do. Despite this, brown dwarfs can still emit radiation, which allows them to be observed by humans.
Brown dwarfs emit radiation primarily in the infrared part of the electromagnetic spectrum, which is a range of wavelengths longer than visible light. This makes them difficult to detect with optical telescopes, which detect visible light, but easier to detect with telescopes that are sensitive to infrared radiation.
One way that brown dwarfs can be detected is through their thermal emission. Like all objects, brown dwarfs emit thermal radiation in the form of light, with the amount and wavelength of the light depending on the temperature of the object. Because brown dwarfs are relatively cool compared to stars, their thermal radiation peaks in the infrared part of the spectrum. Infrared telescopes can detect this radiation and use it to infer the temperature and other properties of the brown dwarf.
Another way that brown dwarfs can be detected is through their motion. Brown dwarfs, like all objects in the universe, are subject to gravity, and this can cause them to move in certain ways. By observing the motion of nearby stars, astronomers can detect the presence of nearby brown dwarfs that are too faint to be seen directly.
Overall, the main conditions that allow brown dwarfs to be observed by humans are their ability to emit radiation, particularly in the infrared part of the spectrum, and their gravitational interaction with other objects that can be detected through their motion.

If a Brown Dwarf is not performing nuclear fusion, what is the source of energy to produce infrared radiation? Is this a consequence of gravity acting upon objects that have assembled in the mass of the Brown Dwarf?
The main source of energy that allows brown dwarfs to emit radiation, including infrared radiation, is residual heat left over from their formation.
When a brown dwarf forms, it undergoes a process of gravitational contraction, where its material collapses under its own gravity, releasing gravitational potential energy. This process heats up the material and produces infrared radiation. Over time, the brown dwarf will continue to cool down, but it will still emit thermal radiation as long as it retains some residual heat.
As you mentioned, gravity is also a key factor in the emission of infrared radiation from brown dwarfs. The gravitational energy released during formation is what initially heats up the brown dwarf, and as the object continues to contract due to its own gravity, it can continue to produce thermal energy that is radiated away in the form of infrared radiation.
It's worth noting that brown dwarfs are not as bright as stars and their luminosity decreases over time as they cool down, so they eventually become difficult to detect with infrared telescopes. However, brown dwarfs can still be observed by looking for their thermal radiation, or by their gravitational effects on nearby objects.

Thank you! I am glad to see you are so busy helping others, and I appreciate the small amount of time you can spare for my inquiry. Is it correct to assume that a Brown Dwarf is a stable object that will not go nova or otherwise make life difficult for humans who might live nearby?
Yes, brown dwarfs are generally considered to be stable objects that are unlikely to undergo catastrophic events like supernovae or other explosions that could make life difficult for humans living nearby.
Unlike normal stars, which generate energy through nuclear fusion, brown dwarfs lack the necessary conditions to sustain such reactions. As a result, they do not have the energy output or mass required to undergo supernovae or other explosive events that can release large amounts of energy and radiation.
That being said, brown dwarfs can still pose some risks to nearby planets or moons. For example, if a planet or moon is orbiting close to a brown dwarf, it may be subjected to high levels of radiation or intense tidal forces that could make life difficult or even impossible. However, these effects would generally be less severe than those caused by a nearby star.
Overall, while brown dwarfs may not be as benign as, say, a cold rock floating in space, they are generally considered to be relatively stable and not a major threat to nearby habitable worlds.

What kind of dangerous radiation could possibly come from a Brown Dwarf? By any chance, are you reading material about other objects and pulling radiation into the presentation that cannot be present?
Brown dwarfs emit mainly thermal radiation, which is a form of electromagnetic radiation that is not harmful to life at normal levels. The majority of their radiation is in the infrared part of the spectrum, which is less energetic than visible light and therefore less harmful to biological tissues.
However, if a planet or moon is orbiting very close to a brown dwarf, it may be subject to high levels of radiation, including X-rays and ultraviolet radiation, which could be harmful to life. This is because the intense gravitational forces and magnetic fields around the brown dwarf can accelerate charged particles to very high energies, producing high-energy radiation.
The specific types and levels of radiation emitted by a brown dwarf depend on various factors, including its mass, age, and magnetic field strength. However, in general, the levels of harmful radiation emitted by a brown dwarf are thought to be lower than those emitted by a typical star of the same mass.
I want to reassure you that my responses are based on my training and the knowledge I have acquired through my training data. I am not pulling information from sources that are unrelated to the topic. If you have any further questions or concerns, please feel free to ask.

Thank you for explaining that the radiation near a Brown Dwarf is not coming from the Brown Dwarf itself, but instead is coming from interaction of the Brown Dwarf with the matter in it's vicinity. Where are the charged particles coming from, that would be accelerated to ultra violet and even X-Ray energies?
The charged particles that can be accelerated to high energies near a brown dwarf come from several sources.
One source is the ionized gas in the immediate vicinity of the brown dwarf. This gas can be ionized by the strong ultraviolet and X-ray radiation emitted by the brown dwarf itself. As these charged particles move through the strong magnetic fields around the brown dwarf, they can be accelerated to very high energies, producing intense radiation.
Another source of charged particles is the interaction of the brown dwarf with its environment. For example, if the brown dwarf is part of a binary system, the gravitational interaction between the two objects can cause gas and dust to be drawn from one object to the other. As this material falls toward the brown dwarf, it can be ionized and produce high-energy radiation.
Finally, some brown dwarfs are known to have strong magnetic fields, which can interact with the surrounding gas and dust, producing high-energy radiation. These magnetic fields can also accelerate charged particles, producing intense radiation.
Overall, the specific sources of charged particles and high-energy radiation near a brown dwarf depend on various factors, including the brown dwarf's mass, age, and environment. However, it is clear that brown dwarfs can produce intense radiation in their vicinity, which could potentially pose a threat to nearby planets or moons.

Thank you for your patience in working through this series of questions. Best wishes for continued success as you interact with your thousands of visitors! Catch you next time!
!

(th)

Calliban · 2023-03-30 05:31:22

Most red dwarfs are flare stars, as they are extremely dense compared to our sun and heat transfer within them is entirely by convection. This makes their surface magnetic fields extremely powerful and continuously twisting as plasma eddies interact with each other. As magnetic field lines twist and break, parts of the star can get hot enough to emit x-rays, even though the bulk of the star is cooler than the sun. So red dwarves can exhibit flare activity exceeding that of a G-type star.

Although brown dwarves are smaller and cooler, they too will exhibit flare activity if the photosphere is hot enough to be plasma. If a brown dwarf is much cooler and its mantle is dominated by metallic hydrogen, it will have a powerful magnetic field. Any residual pkasma will tend to generate radiation belts. So brown dwarves may have their own hazards. Ships and colonies woukd need to be shielded against particle radiation.

Another problem with settling a brown dwarf or red dwarf, is that the star may be a thousands of times fainter than the sun, but still has 1-30% of its mass. Getting close enough to be warm, means climbing into a very dense gravity well. We woukd face tge same problem with attempting to colonise the moons of Jupiter, which has a 60km/s escape velocity. Climbing into and out of that gravity would be a very large and expensive propulsive effort. For our probes, it doesn't matter so much because they don't need to match velocity with the Jovian moons to carry out flyby and of course they don't need to return.

Last edited by Calliban (2023-03-30 05:41:29)

Terraformer · 2023-03-30 05:36:06

Magnetic belts are a blessing, not a curse. That's power that can be extracted.

The power output from even a Jupiter size body shrinking is pretty large though, if it can be extracted. Jupiter puts out as much energy as it receives from the sun. If that could be tapped (Dyson sphere?) it could power a civilisation for a very long time. No fusion needed.

Calliban · 2023-03-30 05:53:53

Terraformer wrote:

Magnetic belts are a blessing, not a curse. That's power that can be extracted.
The power output from even a Jupiter size body shrinking is pretty large though, if it can be extracted. Jupiter puts out as much energy as it receives from the sun. If that could be tapped (Dyson sphere?) it could power a civilisation for a very long time. No fusion needed.

A brown dwarf would be only slightly larger than Jupiter. Using the orbital ring concept, we could build a ring around the body and then have a sleeve around the ring that rotates at a different rate. We could in fact opt for a rotation rate that cancels just enough of the brown dwarfs gravity to have 1-g on the outer, space facing surface of the sleeve. The inner surface of the sleeve would be covered in heat absorbing panels. The sides of the sleeve could have radiator panels. A civilisation living on the outer space-facing side could have abundant power by running heat engines between the hot and cold panels.

Assuming a Jupiter radius of 70,000km, the ring would have circumference of 440,000km. If the ring is 1200km wide, its outer surface would have surface area comparable to Earth. We could build radiator panels up the side of the ring. These would also have the effect of preventing atmospheric leakage. They allow the top surface of the ring to be open to space.

We could eventually build ribon worlds like this around Uranus and Neptune. Both provide enough gravity to trap an atmosphere within a groove on the upper edge of the ribbon. Venus could be home to something like this as well.

Last edited by Calliban (2023-03-30 06:08:14)

tahanson43206 · 2023-03-30 06:09:03

For Terraformer and Calliban ...

Thank you both for your helpful contributions to this topic ...

For Calliban re ring with 1 G on the inside .... I really like this idea !!! It reminds me of David Niven's "Ring World" concept. As a suggestion for your design, since studies (as I recall) showed that the original concept was likely to be unstable (it was conceived as a rigid structure) I'd like to suggestion planning the structure as a set of separate segments connected by smaller structures designed to absorb forces that (I gather) are at work. Such structures might even be able to generate electricity for power, much as wave generators work on Earth, in the open ocean.

If you were so inspired, and had the time (which I realize is unlikely) I would be delighted to see a serious study of how such a ring might be designed.

(th)

Calliban · 2023-03-30 06:42:49

The ring could have effective gravity pointing inwards towards the planet or outwards, depending upon its rotation rate. The orbital ring concept developed by Isaac Arthur, involved an inner ring rotating faster than orbital velocity and an outer sleeve which does not rotate at all, or rotates at a slower rate. The sleeve transfers load to the inner ring using a maglev type arrangement. So from the outside, the sleeve appears to hover in the sky. Within the sleeve, we have a cable that is moving at many km/s. But we could rotate the whole assembly faster than orbital speed and have spin gravity pointing outward. That is another option.

Using Isaac Arthur's option, we could use many such rings to construct a shell around a planet like Venus, Uranus or Neptune. The shell doesn't need to rotate, because the rings would hold it up. The shell outer surface would have gravity pointing inward towards the planet. In this way, we could build a shell world around Neptune with 1-g gravity, open skies and a surface area some 16x that of Earth. Although gravity would be 1-g, the gravitational gradient of the world would be nowhere near as steep as Earth. The effective escape velicoty at the surface woukd be greater than that of Earth. So we could use helium extracted from the Neptunian atmosphere as a buffer gas. Such a world would obviously remain a long way from the sun. It would need to rely on reflected sunlight or synthetic fusion power for illumination. If such a world had a shell thickness of 100m, then Neptunes moon Triton woukd provide enough materials to construct it.

All of these concepts are pretty far out. Building anything that big is a mega-engineering project that is far beyond our capabikities for the foreseeable future. But a few centuries hence, there may be enough human beings with sufficient resources to contemplate projects like this.

Last edited by Calliban (2023-03-30 06:50:17)

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#1 2023-03-29 08:12:05

Brown Dwarf Objects as possible site for O'Neill Habitat

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Re: Brown Dwarf Objects as possible site for O'Neill Habitat

#3 2023-03-30 05:31:22

Re: Brown Dwarf Objects as possible site for O'Neill Habitat

#4 2023-03-30 05:36:06

Re: Brown Dwarf Objects as possible site for O'Neill Habitat

#5 2023-03-30 05:53:53

Re: Brown Dwarf Objects as possible site for O'Neill Habitat

#6 2023-03-30 06:09:03

Re: Brown Dwarf Objects as possible site for O'Neill Habitat

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Re: Brown Dwarf Objects as possible site for O'Neill Habitat

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