Of Orphan Worlds and Interstellar Island Hopping
From Centauri Dreams:
Because of my fascination with exotic venues for astrobiology, I’ve always enjoyed Karl Schroeder’s novels. The Canadian writer explored brown dwarf planets as future venues for human settlement in Permanence (2002), and in his new book Lockstep (soon to be published by Tor, currently being serialized in Analog), Schroeder looks at ‘rogue’ planets, worlds that move through the galaxy without a central star. Imagine crimson worlds baked by cosmic radiation, their surfaces building up, over the aeons, the rust red complex organic molecules called tholins. Or consider gas giants long ago ejected from the system that gave them birth by close encounters with other worlds.
Objects like these and more are surely out there given what we know about gravitational interactions within planetary systems, and they’re probably out there in huge numbers. I’m not going to review how Lockstep uses them just yet — in any case, I haven’t finished the book — but we’ll return to its ingenious solution to time and distance problems in a future post. Right now I just want to mention that one of Schroeder’s characters muses upon ‘a hundred thousand nomad planets for every star in the galaxy.’ Now that’s some serious real estate.
If the number sounds like a novelistic exaggeration, it’s nonetheless drawn from recent work. Schroeder is invoking the work of Louis Strigari (Stanford University), who has studied the possibilities not only of planets ejected from their own systems but those that may form directly from a molecular cloud. The figure of 105 free-floating planetary objects for every main sequence star is from a 2012 paper in Monthly Notices of the Royal Astronomical Society (you can read more about Strigari’s ideas in ‘Island-Hopping’ to the Stars).
Rogue planets would be tricky to find but gravitational microlensing should help us set constraints on their actual numbers, and as we’ll see below, direct imaging has its uses. If rogue worlds are available in such quantities, we can imagine a starfaring culture capable of exploiting their resources. We can even speculate that a thick atmosphere that can trap infrared heat coupled with tectonic or radioactive heat sources from within could sustain elemental forms of life even in the absence of a star. Tens of thousands of objects in nearby interstellar space would obviously be a spur for exploration.
A Newly Found Orphan World
Eighty light years from Earth floats a solitary planet that has been discovered through its heat signature in data collected by the Pan-STARRS 1 wide-field survey telescope on Maui. In mass, color, and energy output, the world is similar to directly imaged planets. As you might expect, PSO J318.5-22, a gas giant about six times the mass of Jupiter, turned up during a search for brown dwarfs, delving into the datasets of a survey that has already produced about 4000 terabytes of information. The discovery was then followed up through multiple observations by equipment on nearby Mauna Kea, with spectra from the NASA Infrared Telescope Facility and the Gemini North Telescope indicating the young, low-mass object was not a brown dwarf.
Image: Multicolor image from the Pan-STARRS1 telescope of the free-floating planet PSO J318.5-22, in the constellation of Capricornus. The planet is extremely cold and faint, about 100 billion times fainter in optical light than the planet Venus. Most of its energy is emitted at infrared wavelengths. The image is 125 arcseconds on a side. Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium.
“We have never before seen an object free-floating in space that that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone,” explained team leader Dr. Michael Liu of the Institute for Astronomy at the University of Hawaii at Manoa. “I had often wondered if such solitary objects exist, and now we know they do.”
The find is interesting on a number of levels, not least of which is that observations of gas giant planets around young stars have shown that their spectra differ from those of L- and T-class brown dwarfs. Young planets like these, according to the paper on this work, show redder colors in the near-infrared, fainter absolute magnitudes at the same wavelength and other spectral peculiarities that suggest the line of development between brown dwarfs and gas giant planets may not be as clear cut as once assumed. The paper makes clear how complex the issue is:
PSO J318.5−22 shares a strong physical similarity to the young dusty planets HR 8799bcd and 2MASS J1207−39b, as seen in its colors, absolute magnitudes, spectrum, luminosity, and mass. Most notably, it is the ﬁrst ﬁeld L dwarf with near-IR absolute magnitudes as faint as the HR 8799 and 2MASS J1207−39 planets, demonstrating that the very red, faint region of the near-IR color-magnitude diagram is not exclusive to young exoplanets. Its probable membership in the β Pic moving group makes it a new substellar benchmark at young ages and planetary masses.
A landmark indeed, and here the Beta Pictoris moving group, a collection of young stars formed about twelve million years ago, is worth noting. Beta Pictoris itself is known to have a young gas giant planet in orbit around it. The newly detected PSO J318.5−22 is lower still in mass than the Beta Pictoris planet and it is thought to have formed in a different way. The paper goes on:
We ﬁnd very red, low-gravity L dwarfs have ≈400 K cooler temperatures relative to ﬁeld objects of comparable spectral type, yet have similar luminosities. Comparing very red L dwarf spectra to each other and to directly imaged planets highlights the challenges of diagnosing physical properties from near-IR spectra.
The beauty of objects like these from an astronomical point of view is that we don’t have to worry about filtering out the overwhelming light of a parent star as we study them. Co-author Niall Deacon (Max Planck Institute for Astronomy) thinks PSO J318.5−22 will “provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth.” The discovery also gives us much to think about in terms of future explorations as we contemplate a cosmos in which perhaps vast numbers of planets move in solitary trajectories through the galaxy.
I like the idea of targeting “rogue” planets as potential interstellar missions within the next 100 years. The probes can be smaller and the fuel problem won’t be as bad.
Karl Schroeder isn’t the only author who has used rogue planets as interstellar destinations. The old Space: 1999 television series addressed it as well as Peter Watts Blindsight. Good stuff.
Open Minds TV: Alien conspiracy theories help promote new Denver International Airport build-out
From the article:
Denver International Airport (DIA) is the focus of a myriad of conspiracy theories, a fact that they took advantage of this week to promote a commemoration event for reaching the midway point of a large build-out that includes a new public plaza and commuter trains from downtown Denver.
DIA has been plagued with conspiracy theories beginning with trouble during its construction that set it back months. Some said this trouble was actually a ruse to build underground tunnels and rail stations to be used by the elite and possibly even extraterrestrials. Then upon its opening came the discovery of morbid murals depicting scenes of oppression, further evidence for conspiracy theorist that malicious intent was at play. The final draw was the capstone on a time capsule sponsored by a couple of the local Freemason lodges that uses the term “New World Airport Commission.”
All of this was compelling enough evidence for Jesse Ventura to investigate on his television show Conspiracy Theory. More prosaic and well researched answers, if you need them, are presented in this article by the local Denver newspaper Westword.
DIA’s twitter feed hinted at their intent to use these conspiracy theories to promote the event with a tweet Tuesday morning which said they would be having some fun with the event, and that they would be “divulging some strange activity.” One tweeter speculated, “THEY’RE UNLEASHING THE DEMONS FROM THE MURALS.”
The alien conspiracy marketing of the event began with a tweet by DIA regarding “a strange find” that was discovery during construction. Attached was a picture of what appears to be a partially recovered alien skull, huge eye socket and all.
They continued with some witty tweets addressing all of the conspiracies associated with the airport. Here are some examples:
They even engaged some of the conspiracy theorists, tell one that they could not tell him they the Freemason time capsule referenced a “New World Airport Commission,” because, “We’d tell you but then…” When his questions persisted, they simply told him he knew too much. Later in the evening, a time capsule commemorating the construction midway point was buried, and sure enough an alien was involved as could be seen in this picture they tweeted.
Alien seen under time capsule buried to commemorate the midway point in DIA’s new construction project. (Credit: Denver International Airport)
Another couple of tweets showed what appeared to be former Denver mayors in a video discussing and having some fun with the conspiracy theories. They tweeted, “Four Denver mayors come together to talk about DIA conspiracy theories.” They also tweeted this picture:
Apparent phone call with an alien at the DIA event commemorating the midway in DIA’s new construction project. (Credit: Denver International Airport)
Their efforts seemed to pay off as they garnered a lot of local news attention. I must say I found their tweets were very amusing. They ended the night with this final tweet:
Denver Int’l Airport@DENAirport
Thanks twitterers for having some fun with us today. Long live the #conspiracy theories! #DIAmidpoint2 Retweets 1 favorite