Evidence from nearby white dwarfs suggest rocky exoplanets are alien to Earth
The uncertainty of science: Evidence from 23 white dwarfs, all located less than 650 light years from Earth, suggest that the make-up of rocky exoplanets are likely very alien to Earth, with minerals and chemistry that is found nowhere in our solar system.
They found that these white dwarfs have a much wider range of compositions than any of the inner planets in our solar system, suggesting their planets had a wider variety of rock types. In fact, some of the compositions are so unusual that Putirka and Xu had to create new names (such as “quartz pyroxenites” and “periclase dunites”) to classify the novel rock types that must have existed on those planets.
“While some exoplanets that once orbited polluted white dwarfs appear similar to Earth, most have rock types that are exotic to our solar system,” said Xu. “They have no direct counterparts in the solar system.”
Putirka describes what these new rock types might mean for the rocky worlds they belong to. “Some of the rock types that we see from the white dwarf data would dissolve more water than rocks on Earth and might impact how oceans are developed,” he explained. “Some rock types might melt at much lower temperatures and produce thicker crust than Earth rocks, and some rock types might be weaker, which might facilitate the development of plate tectonics.”
The data from the white dwarfs is believed to be the leftover material of exoplanets that were absorbed by the star, sometime in the far past.
First, this result should not be a surprise. To even think for a second that planets in other solar systems would be similar to the planets in our solar system is unrealistic. Even in our solar system we have found that practically every single body — planets, moons, asteroids, comets — is remarkably unique. Other solar systems are sure to be even more alien.
Second, the result here is somewhat uncertain. The scientists were not gathering data of actual exoplanets, but what is believed to be the remains that had been swallowed by the stars. The scientists then extrapolated backwards to come up with these alien rock types. The result, while very suggestive, must be taken with some skepticism.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: Evidence from 23 white dwarfs, all located less than 650 light years from Earth, suggest that the make-up of rocky exoplanets are likely very alien to Earth, with minerals and chemistry that is found nowhere in our solar system.
They found that these white dwarfs have a much wider range of compositions than any of the inner planets in our solar system, suggesting their planets had a wider variety of rock types. In fact, some of the compositions are so unusual that Putirka and Xu had to create new names (such as “quartz pyroxenites” and “periclase dunites”) to classify the novel rock types that must have existed on those planets.
“While some exoplanets that once orbited polluted white dwarfs appear similar to Earth, most have rock types that are exotic to our solar system,” said Xu. “They have no direct counterparts in the solar system.”
Putirka describes what these new rock types might mean for the rocky worlds they belong to. “Some of the rock types that we see from the white dwarf data would dissolve more water than rocks on Earth and might impact how oceans are developed,” he explained. “Some rock types might melt at much lower temperatures and produce thicker crust than Earth rocks, and some rock types might be weaker, which might facilitate the development of plate tectonics.”
The data from the white dwarfs is believed to be the leftover material of exoplanets that were absorbed by the star, sometime in the far past.
First, this result should not be a surprise. To even think for a second that planets in other solar systems would be similar to the planets in our solar system is unrealistic. Even in our solar system we have found that practically every single body — planets, moons, asteroids, comets — is remarkably unique. Other solar systems are sure to be even more alien.
Second, the result here is somewhat uncertain. The scientists were not gathering data of actual exoplanets, but what is believed to be the remains that had been swallowed by the stars. The scientists then extrapolated backwards to come up with these alien rock types. The result, while very suggestive, must be taken with some skepticism.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
I am extremely skeptical of these results…. For several reasons.
Firstly, the actual measurements themselves must be taken with a grain of salt. As proven recently with Venus, it is difficult to accurately measure the make up of atmosphere in close neighbors to earth, never mind tiny stars light years away.
My main reason for doubting the conclusion drawn from the data is that whatever they are detecting has been exposed to the different forms and levels of radiation generated by the explosion of a star going red giant, and then the implosion into the white dwarf we observe today.
We have absolutely no proof of what happens to matter during these cataclysmic events. Theory, yes. Proof, no. We build particle colliders to try and approach the energy of these kind of events, and are suprised and educated by the results. It seems a little rich to me to read the spectrography of elements that have been bombarded with God knows what kind of particles, baked and frozen, and extrapolate back to the planets that once orbited the original star.
Call me old and grumpy and a skeptic, but I remain very skeptical!
I wrote something about 10 years ago on the Kepler mission:
https://www.amssolarempire.com/Blog/?p=58
I remember people coming up with reasons why planetary systems were rare-to-nonexistent before telescopes using starlight nulling starting picking up the first extrasolar far-orbiting jovians like Fomalhaut-b.
Then the “story” changed to why every extrasolar planet was going to be some gigantic frozen hydrogen world, and the only thing in the sky were protostellar or stellar objects. Even though at the time it was clearly a limitation in our instruments, not an indication of what was truly out there. The wobble-method picked up hot-jupiters: Very massive objects whose gravity perturbed the trajectory of the star in way you could pick out with spectroscopy.
I remember being rather enthusiastic about the proposed Terrestrial Planet Finder mission back in the early 2000’s, and I still hope some agency somewhere manages to launch a telescope along those lines someday. Being able to directly resolve the reflected light from the planets will let us know far more about them.
The transit method started coming into heavy use in 2010-ish/2011: Kepler picked up thousands of new planets. I remember it being “common wisdom” in “hard science fiction” that there was next to no chance that planets could exist in the habitable bands of the more plentiful K and M stars (orange/red) because they are much narrower than Sol’s habitable band. Well, interestingly enough, it turns out those systems are also more densely packed, and plenty of things end up in the habitable bands of M-stars – whether they are “Earthlike” (whatever that ends up meaning in the end) who knows? The sparseness of the Solar system could be entirely accidental (Jupiter’s fault, or something), or it could be some sort of central-mass dependent Titus-Bode thing.
Anyway, it’s interesting, because prior to having any solid knowledge (to the extent we have it now!) of what was out there orbiting other stars, there were all these assumptions, and the assumptions seemed to tend towards pessimistic pictures of boring, barren, dead universes. Instead, it’s seeming more like “anything goes”.
Also, yes – skeptical of anything we have to get so indirectly, and more-so of “modelling”. I haven’t really seen computer models give good results for anything but painfully simple problems where the numerical behavior of the system is nice: Things like linear elastic isotropic materials in FEA.
Even the Kepler transits have to be taken with a grain of salt: Periodic repetition of a dimming of a star could be a planet, or an unusually persistent sunspot, or variable activity, or or or. The relative motion by which they’ve backed out perturbative graviational influence of the presumed planets on each other, and a coherent heirarchy of masses: That’s suggestive that something is orbiting.
Why we need something like TPF: Very long baseline interferometers to pick out the planets from the starlight and get light off their atmospheres directly!
Still, the contents of the universe are pretty extravagant. Some sort of “dismal blandness bias” doesn’t seem to fit the experience of anything but perhaps the more dismal parts of human history. Surely nothing wrong with speculation?
If the study holds, then ‘Earth’ is good name for our world…as the Milky Way’s Golem…life breathed into us alone…Fermi can rest…