These planetars stoke the scifi imagination. They are the perfect hideaway for a fleeing civilization... or deadly weapon. What kind of life could exist on a planet without a star?
Even when the scientific payoff is limited, the payoff to the imagination is immense.
In Passages in the Void[1], these planets are the only places the machines were willing to reincarnate humanity after deciding that stars were too dangerous, having suffered the anguish of their humans being extinguished by our own Sun.
[1] A series of short stories by a Roger Williams, tagged localroger on kuro5hin, wrote back in the day. I gathered the parts together into an ePub suitable for iBooks. I'm checking with the author now to see if I can make it available. You can always read it on the kuro5hin site, linked from http://localroger.com/ (The Metamorphosis of Prime Intellect is something else entirely.)
I read this brilliant short story once where the Earth had been 'stolen' by a massive rogue planet (the earth started to orbit it instead of the sun). A family had survived by building a air tight shelter and having a constant fire burning. They had to go out to fill up buckets with frozen oxygen to bring back and defrost.
Yeah; the Earth would remain warm for millennia -its 55 degrees underground only a few feet all year around. I always wondered, why didn't these people just live in a basement or underground garage or cave or something? Would have massively simplified their lives.
Those who did likely died. "Pa says that all sorts of cliffs and buildings toppled, oceans slopped over, swamps and sandy deserts gave great sliding surges that buried nearby lands."
Basements don't help. Too close to the surface. You get some insulation from the earth, yes, but it's not much. The gradient is something like 25°C per km of depth/1°F per 70 feet of depth. They live at liquid helium temperatures, so you'll have to get pretty deep to be at a stable temperature.
That's to get to the stable point. It takes a while for the earth to cool down. Assuming 100m depth, ... I tried, but I couldn't figure out the physics. The frost depth in some parts of the world is over 2 meters, so a basement wouldn't be all that useful. Compare the temperature of -50C for winter in Siberia to -270C for the many years of the story. You'll also have liquid air leaking through any cracks and pooling in the bottom - the parts at least which don't drain to cover the frozen sea.
But how deep do you need to go to be ahead of the chill? I found a table in the "permafrost" page on Wikipedia, which linked to http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=Get... . That looks like it has enough details to figure out how long it would take for a surface temperature near absolute zero to penetrate 100m into the ground, causing an initial subsurface temperature of 12C to drop to 0C. Can you figure it out?
In any case, perhaps others might have survived in deep caves, using geothermal heat. It's doesn't mean that the people in this story couldn't have survived using some other means.
I'm not convinced our atmosphere would freeze at all; it would be winter but the stable temperature is hard to calculate as you say. Antarctica hasn't gotten appreciable heat in millennia and the air isn't freezing there. I know, convection brings some warm but still.
The premise to the story is impossible, so it's hard to criticize the author for thinking that the entire atmosphere would freeze.
http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442(1997)0... says that the the Antarctic Circle gets about 120W/sq. meter averaged over the entire year. That's about what I expected since sin(23.5 degrees)snow albedo of 0.63 months/12 months * 1000 W / sq. meter solar power -> 60 W/sq. meter. While not a lot, it's still appreciable.
Assuming everything is radiated out to space, Stefan-Boltzman says that (5.670373e-08)T*4 = 120 W/sq m. => T = 214K, which means Antarctica would have a overall average temperature of about -60C, if only due to solar heating.
Interestingly, "Other scientists have estimated that temperatures on any possible permanently lit spot [on the Moon] would be comparatively balmy, though still a frigid minus 58 Fahrenheit (-50 Celsius), give or take a little." This is in concurrence with my calculation.
Which means that solar heat alone is enough to explain why the temperature does not get to the -180C needed to liquify oxygen.
The planet was found to be between 50 and 120 millions years old, with a temperature of approximately 400 degrees Celsius, and a mass four to seven times that of Jupiter.
Not exactly sure what "temperature" refers to there, but Wikipedia tells me that Jupiter itself has a surface temperature of less than -100 degrees C. So even without a star, it's rather substantially warm. However, at Jupiter's distance, the solar radiation received from the sun is rather minimal anyway.
I'm most of the way through reading Neil deGrasse Tyson's book "Origins", and I just finished chapter 24 last night, which deals with this exact subject.
By the way, it looks like the entire book is available online; this[1] is a link to the section of ch. 24 that talks about these star-less planets and the possibility that they contain life.
First, he points out the "extremophiles" that exist on earth -- for example, organisms that live on the sea floor, where the heat from the sun is fully nullified. Despite the great atmospheric pressure and the lack of light and heat, life still thrives in these environments. One of the factors that facilitate life at these extremes are the geothermal processes (vents in the sea floor) which are purely disconnected from the events of the sun, and completely powered by our magma core.
As we know, many planets are suspected to have molten cores, which are the result of their formation and which will continue to remain such for billions of years (we will probably be wiped out by our Sol turning into a red giant before our the Earth's core will lose it's energy). As such, though it'd be near-impossible for life to survive on the surface of a planet that is not a part of any solar system, under the surface life could be bountiful.
The core of planets do not remain hot for billions of years based on their formation. They remain hot because they have radioactive material that continues to generate heat.
Before the discovery of radioactivity invalidated the calculation, the fact that the Earth's interior is still hot was used by Lord Kelvin to set an upper limit of 40 million years for the Earth's age.
Things are not the same for all kinds of planets. A rocky planet the size of Mercury is going to cool off much faster than one the size of Earth. This is largely due to the difference in volume to surface area ratios and related effects. A more massive planet will have a much higher amount of heat left over from formation, and it will lose that heat slower. Plus, it will have a higher quantity of radioactive elements relative to its surface area. This is why the Moon is geologically inactive while the Earth still is, despite being made of mostly the same stuff.
Once you scale up to gas giants these factors become even more important. Those planets retain a crap ton of heat from their initial formation and are comparatively inefficient at radiating it away into space. More so, they continue to generate heat through ongoing settling (raining of Helium down to lower levels of the atmosphere, for example).
That's not the case for Earth though, is it? I had thought it was the tremendous pressures that kept the internal core molten. If it was radiation wouldn't it be enough to destroy us living in such close proximity?
I am barely qualified to call myself even an amateur astronomer, so sorry if I've misinterpreted anything.
edit: re-reading the passage, it sounds like it's a combination of both (bottom of p.245, 246).
> If it was radiation wouldn't it be enough to destroy us living in such close proximity?
Different kinds of radiation differ by how deep they penetrate matter. Simplifying a bit you can imagine that for every atom the radiation passes, there's a probability that it interacts / gets absorbed.
Radiation that passes thousands of kilometres of rock without interaction will have a rather low probability of interacting with a mere metre (or so) of human.
Larry Niven's Known Space books deal with this. They put a civilization of herbivorous creatures called Puppeteers on a group of sunless planets accelerating away from a catastrophe in the galactic center. One enjoyable aspect comes from the creatures' herd-like, risk-averse nature, a hold over from their distant past as prey animals. They dream of fleeing forever, enjoying a nomadic existence in the voids between galaxies.
Actually, I think their plan is to go to the Magellanic clouds, following the rest of the Known Space species who would get there before them via Hyperdrive.
It's been awhile since I've read the series, the Ringworld novels bored me.
Damn, I forget the name of the story, but I read one set on such a rogue planet. They were facing a catastrophe - their low-temperature planet was going to pass through the solar system, and they needed to work out a way to prevent themselves from being cooked to death.
Wish I remembered the author or title, and I wish even more that the author would expand it into a full-length novel.
Looks like it was detected in the infrared. The article is a bit light on detail, but on the face of it it's an absolutely astonishing achievement to detect a planet-sized body with an earth-based optical telescope.
Apparently the atmospheric absorption of infrared is pretty decent for ground-based observation. Atmospheric seeing in the near-infrared is still a concern though.
There are two "planet" definitions, depending on if the object in question is in the solar system or outside. The terminology for the later is not as well settled. You might see "free floating planet" or "rogue planet" or the more general term "planetary-mass object" (or PMO or planemo). (The actual paper uses 'free floating planet' and 'planetary-mass object'.)
In any case, if the official position is that a "dwarf planet" is not a planet then it's not hard to see that a "free floating planet" need not be a "planet."
If you read the article all the way towards the end, you will see that it's not exactly "lonely". From the article:
The planet is in fact called CFBDSIR2149 and appears to be part of a group of very young stars known as the AB Doradus Moving Group. “This group is unique in that it is made up of around thirty stars that all have the same age, have the same composition and that move together through space. It’s the link between the planet and AB Doradus that enabled us to deduce its age and classify it as a planet,” researcher Lison Malo explained.
I find it fascinating that we have identified a group of stars that are (i'm assuming) moving in synchronous towards a general direction. I can only theorize that it was caused by perhaps a giant supernova that flung all of these stars/planets outwards but it does make you wonder what caused it exactly.
It says that the image is a photo. Is that really so?
It says that the planet has a temperature of approx 400 degrees Celsius. That is hot. I would have expected it to be deadly cold, esp since it never managed to initiate nuclear reactions in its center. Why is that?
UPDATE: Here's its wikipedia page. 100 light years way from earth, so there is no way it's a photo. Also, wikipedia calls it a brown dwarf, which would explain the temperature:
http://en.wikipedia.org/wiki/CFBDSIR2149-0403
The source of the image, an European Southern Observatory press release (mentioned in the HBL article, linked in the Wikipedia article) gives it a title of "Artist’s impression of the free-floating planet CFBDSIR J214947.2-040308.9".
Would anyone like to explain why this planet would have a temperature of 400C (I was picturing it being really cold)? Is this because of its mass/size, more related to its gaseous composition or both?
I think that the news here is that is has been determined that it is not a brown dwarf. See the paper[1] for more details. Though I'm not sure why the distinction between giant planet vs cold tiny star is so important.
Even when the scientific payoff is limited, the payoff to the imagination is immense.