A "Super-Earth" called GJ 251c has recently been identified in the regular searches being carried out for possible signs of life. This one is less than 20 light years away putting it in the list of easily observed planets to look at regularly.
The planet, known as GJ 251c, orbits a red dwarf star 18.2 light-years away in the constellation of Gemini, the Twins. The planet's mass is four times greater than that of Earth, making it a 'super-Earth' — a rocky planet larger and more massive than our own.
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GJ 251c was discovered thanks to observations spanning over 20 years, during which scientists looked for a slight wobble of the world's parent star incurred by the planet's gravity. As the star wobbles ever so slightly toward and away from us, we see a Doppler shift in its radial velocity that can be measured with a spectrograph.
An interesting side note to this discovery is that there's another known planet in this system, named (brace yourself) GJ 251b. This one is a much smaller planet discovered in 2020 that orbits its star every 14 days at a distance of 7.6 million miles. By comparison, Mercury's orbit takes 88 days and it orbits our sun much farther away than GJ 251b, 36 million miles from the sun.
...Using archive data from telescopes worldwide, a team of astronomers, including Mahadevan, was able to refine the accuracy of the radial velocity measurements for planet GJ 251b
The team then combined this refined data with brand new, high-precision observations from the Habitable-Zone Planet Finder (HPF), which is a near-infrared spectrograph on the Hobby-Eberly Telescope at McDonald Observatory in Texas. This revealed a second planetary signal belonging to a four-Earth-mass world orbiting the star every 54 days. That was then confirmed by measurements with the NEID spectrograph on the 3.5-meter WIYN telescope at Kitt Peak National Observatory in Arizona.
Artist's impression of GJ 251c on the left with GJ 251b, in the middle, closer to its red dwarf star on the right. (Image credit: University of California, Irvine.)
GJ 251c is probably a bit too far away to use the James Webb Space Telescope (JWST) to search for or analyze its atmosphere. There are plans around for 30-meter-class telescopes that open other possibilities and even bigger, more specialized telescopes after that, out into the 2040s. The unmentioned elephant in the room is that red dwarf star.
At 36% of the mass of our sun, the star GJ 251 is a red dwarf. Astronomers have now found numerous rocky planets in the habitable zone of red dwarfs, including Proxima Centauri b, TRAPPIST-1e and f, and Teegarden's Star b. However, red dwarfs are notorious for having violent tempers that belie their diminutive stature, releasing regular powerful flares that can over time strip a planet of its atmosphere. For example, the JWST's observations of the inner three planets of TRAPPIST-1 find no evidence for an atmosphere, while its observations of the fourth planet, e, are so far inconclusive. Some astronomers are now growing skeptical that Earth-like worlds can thrive around red dwarfs.
The big picture is even a bit more complex than that because GJ 251 is a bit on the large side for a red dwarf, and that means the usual "Goldilocks zone" (the orbital shell where conditions are most favorable for life) is a little farther from the star and that might help.
It is possible that GJ 251c is far enough away from its star to have avoided the worst of its temper tantrums, and, if armed with a thick atmosphere and strong planetary magnetic field, it could have resisted the star's stellar wind from stripping its atmosphere away.
That makes the short version something like, "interesting, but don't sit on the edge of your seat waiting for news." The youngest of us might live long enough to see that news.
If it's over 1.5G, or the pressure's too high, or the radiation is too high (or too low) then, no, no life.
ReplyDeleteThe parameters that Earth met to start, yet alone sustain life as we know it are crazy.
Jovians that started in closer to the Sun that then moved out while cleaning the inner orbits of ash and trash. And then said jovians hanging around and cleaning up incoming ash and trash from outside the system.
A star just the right size and age and really meek in radiation activity.
A planetoidal moon of just the right size to get trapped by the planet's gravity and slow said planet's revolution and affect the water and the planetary crust (waves and flexing of the planet's crust.)
A planet, Earth, with just the right amount of heavy metals, and an active metallic core, and a functioning radiation shield, and a crust and lots of water, at just the right orbit from the local sun. And with just the right amount of gravity, not too light and not too heavy, that allowed chemicals to form at just the right gravity.
Periodic bombardments by meteor swarms to add just the right amount of spice to the planet.
And so much more.
All of that is the only reason we have life on this Earth. Almost a miracle, no?
And then to find another planet or planetoid that has 2/3rds of the 'coincidences' that the Earth had/has? Umpossible odds.
I happened to hear an interview yesterday on Glenn Beck's show about this very subject. It was with a guy named Martin Rees and if I understood all of it, he's a high level guy at the American Enterprise Institute. He has a book out called "Just Six Numbers" about how the universe basically couldn't exist if the six physical constants he focuses on weren't very close to what they are.
DeleteI've been down that mental road many times, and while I have the concept pretty well deep in memory, I'm thinking of getting the book. Maybe just a Kindle version - "plain old books" outnumber everything else in this house bigger than grains of sand. As someone noted, it almost takes more faith to not believe the Bible than to believe.
More and more I believe we are very very alone in this universe. Which, since real aliens, if they exist, will be very alien, might be a good thing.
DeleteIDK. Throughout our history every time an advanced people met 'primitive' people there was a war and the primitives are wiped out. I don't see humans accepting alien overlords no matter how benevolent.
ReplyDeleteIf we even understand the aliens. HP Lovecraft wrote his 'elder gods' as creatures that were so alien the concept would drive mere men insane.
DeleteThink far less of 'Star Trek' and far more really bad LSD trip through a river of bloated corpses. Why? Well, they're... alien.
Just look at the trouble we've had understanding Islam and all the muslims. Or the Imperial Japanese before and during WWII. Or the Soviets back then or the Russians now. Or China in any of its varied forms. Now take that and keep the weirdness and remove the humanity and that's most likely real aliens if they exist.
As to encountering real aliens, unless they have some handwavium that breaks the physics of the universe, even if they exist the probability of us humans encountering them in any reasonable time span (think before our Sun kills us all) is slim to none.
If you're thinking of the vaunted Drake Equation, which says "there are sooo many stars and a certain percentage of those stars have to have planets and a certain percentage of those planets are in the right place and a certain percentage of those planets must have or will produce life and...', well, bat-poop. That's all hopium and handwavium even more handwavium than warp drive and mass conversion power systems.
First, we have no idea about all the varied and multitudinous little miracles that allowed life here on this lonely planet to spring forth. Past six or seven 'coincidences' the mathematical combinations start exceeding the number of grains of sand.
Second, we haven't picked up any signs of intelligent life, at all. We can pick up the radio signal of stars back nigh unto the formation of the first stars, but we haven't picked up any signals that might be artificial.
Third, why? As in why would they come here? Want minerals, go mine an asteroid or an Oort cloud object. Want water, go mine an asteroid or Oort cloud object. Want carbon or silica or whatever your life-form is based on, yep, go mine an asteroid or Oort cloud object. Seriously, if you have the ability to go interstellar, then you have the ability to go systemwide. Gas giants can be mined for... gasses. Rocky balls can be mined for whatever they have. At our present rate of resource-usage increase, we'll run out of resources in this planetary system (and the Oort cloud) about the time the Sun goes blooiee and kills us all.
Crowded planet? Huge rotating space habitats are cheaper than trying to go interstellar. And have the benefit of being able to be spun up to 1G at 1atmo and have enough radiation shielding that it meets the radshielding of Earth. And you could have these habitats as far out as... the Oort Cloud.
Except for wanting to know what's out there, or to escape the eventual solar destruction of Earth, there's no need (and it's just physically really difficult) for us to go outside of the Sol system. Same goes for Aliens. No need and physically hard to leave their systems of origin, if they exist at all.
Beans, that's one of the most wonderful things I've read in a long time.
DeleteThe laws of physics seem to have been designed to prevent planets from interacting. We look at the speed of light and think that's amazingly fast, 300 million meters/second or 186,000 miles/sec. It's wonderful for radio/light, but we have nothing else that can get anywhere near that speed.
Problem is, it's not even that good for radio, except here on Earf. A conversation with a friend on the moon would be a bit awkward but workable with the 1.4 second delay each way. It just gets worse from there. The sun is over 8 minutes away. Mars is more like 4-1/2 minutes but that varies widely over a year.
Basically, if we could get to "just about" the speed of light, it would be great for building out our solar system, but as soon as you talk about traveling to another star system you're talking years. It's around a half hour to Jupiter but all you can say is that beats the crap out of taking years to get there, like the Voyagers and other satellites have taken. There's no calling home to talk with the next level up commanders or whomever, when to get your advice (or orders, whatever) takes years.
Forget intergalactic. Just to get to the other side of our galaxy takes a hundred thousand years. I haven't run any numbers but even with time contraction and dilation, people wouldn't live long enough to get there on a ship running to the far side of the galaxy.
If the speed of light is really the ultimate speed limit of the universe.