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ProtoJeb21

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  1. On Wednesday, two separate teams of astronomers released their findings about water vapor detected in the atmosphere of the temperate Super-Earth/Mini-Neptune K2-18b. Naturally, the press went nuts with this story. I’ve seen a lot of articles calling K2-18b a “rocky” and “habitable” planet, and several annoyed astronomers in response to said articles. The thing is, even though the detection of water clouds in a small habitable zone planet is a landmark discovery, it does NOT immediately prove that K2-18b is habitable. Let’s start with the basics...which are already a little confusing. There are two sets of parameters for the host star; the first, which has been used most often and in the initial discovery and RV result papers on the planet, put K2-18 at around 39-42% the radius and mass of the Sun. The second, newer set uses Gaia and 2MASS data, and puts the star at about 47-49% the radius and mass of the Sun. This discrepancy is important because it radially changes the composition of K2-18b. All studies agree that the planet is in a 33-day orbit around a small red dwarf, gets similar sunlight as Earth, and is between 8 and 9 times the mass but is significantly less dense than Earth. Here we get into the first thing many of those news articles got wrong: K2-18b is NOT a purely rocky world. The older papers put the planet at 8-8.5 Earth masses and 2.2-2.4 Earth radii, with a density of roughly 3.5 g/cm3. This implies K2-18b has a large rocky interior, but also a significant fraction of volatiles, either a water mantle, a thin H/He envelope, or a combination of both. The H/He envelope for a planet of this size and density would be less than 1% of its total mass, likely below 0.5%. However, the newer radius estimate of 2.7x Earth (with a density down to 2.2-2.4 g/cm3) can allow for a thicker H/He up to 2-3% of the planetary mass. Even with this level of uncertainty, K2-18b can be ruled out as having a solid Earth-like surface. The detection of water vapor actually makes the chances of K2-18b habitable even worse. If the atmosphere was made of heavy molecules (N, O2, CO2, etc), water vapor would be hard to detect because such an atmosphere wouldn’t be as high up. However, a primarily hydrogen and helium atmosphere would allow for water to be detected more easily, even if it’s less than 0.1% of K2-18b’s atmospheric composition. The strong detection of water vapor means that K2-18b has retained at least most of its primordial H/He envelope, which is very bad for the development of life. One important thing to note is the exact abundance’s of water and H/He are still unknown. Could K2-18b only have a small amount of hydrogen on top of a water mantle? Sure, but it could also be a dry rocky core with a thicker H/He envelope and no chance of any sort of life. The point is, K2-18b is a pretty bad “potentially habitable” planet; it may be a great stepping stone to characterizing the atmospheres of small temperate planets, but it certainly isn’t the jackpot just yet.
  2. I guess one of my wishes has been granted: I was hoping for an LHS 1140 b like planet (a gigantic temperate Super-Earth with >2g), and one of the few planets revealed in the Q&A does seem to fit this description. No hints to whether it orbits a red dwarf or a more Sun-like star.
  3. I’m not surprised about the lack of an atmosphere; orbiting closer to a feisty red dwarf than Callisto does to Jupiter, LHS 3844b is practically staring down the gun barrel of its star, and is subjected to far greater radiation than most other red dwarf planets. What I am surprised about is its relatively cool temperature. Yes, a day side temperature of ~1100 K is high, but the planet is orbiting so close to such a dense star that I expected significant tidal forces to warm LHS 3844b to higher temperatures, probably at least 1300-1500 K. There is currently no evidence of tidal forces melting parts of the crust all around the planet; however, tidal-induced volcanism on a smaller scale cannot be ruled out. I spoke to Laura Kreidberg a few weeks ago, and she said that her analysis was not sensitive enough to detect night side temperatures below ~700 K, which means that less dramatic tidal heating would’ve gone by undetected. LHS 3844b would be an absolute nightmare to land on if someone ever makes a mod for KSP with it. It lacks an atmosphere like Tylo, but 1.) orbits very close to a star, 2.) probably has magma on the surface, 3.) is hotter than Eve, and 4.) could have up to TWICE the surface gravity of Tylo.
  4. I hope we get some new systems that are based on known exoplanetary systems, like some around red dwarfs or with very compact orbits or with several habitable planets, maybe even analogues to nearby systems like Alpha/Proxima Centauri, LHS 1140, TRAPPIST-1, Tau Ceti, etc. The first glimpses of the new planets are already extremely promising (a ringed Super-Earth, tidally heated binary planets) and I hope there will be a large selection of unique places to go to.
  5. It looks like there will be a binary planet system being ravaged by each other’s tidal forces, and maybe a young star system with multiple ringed planets.
  6. This finally brought me back to the forums after....I don’t even know how long. I didn’t expect a full-fledged sequel to KSP, or the inclusion of interstellar travel, exoplanets, colonies, or multiplayer. I can’t wait to see what new systems and planets will be in the game!
  7. So, the center core was lost....again. I stand by my belief that SpaceX is cursed to never recover a Falcon Heavy center core.
  8. TESS is specifically avoiding the zodiac for its primary mission; however, maybe it could cover that area in its next mission extension. Also, here’s a new study about the potential habitability of the Teegarden planets: https://arxiv.org/abs/1906.07704 For Earth-like atmospheric properties, Teegarden b and c would have a wide but differing range of habitable locations. Teegarden b could have a mostly or entirely inhospitable day side with maximum temperatures reaching 550 K. However, the entire night side could be warm enough for liquid water, leaving any life without access to photosynthesis unless there are small lakes or rivers in the terminator boundary. Teegarden c could resemble a more typical Eyeball Planet, with only the immediate substellar point being too hot (400 K at the max) for liquid water. Between 30 and 75 degrees from the substellar point, temperatures are conducive for life, but afterwards it drops below 270 K and could result in a night side ice cap.
  9. Ever since the seven Earth to sub-Earth sized planets of TRAPPIST-1 were announced all the way back in 2017, I was wondering if this system was unique, or if other tiny red dwarfs could host multiple small rock-dominated planets in temperate orbits. A new study of the M7 ultracool dwarf known as Teegarden’s Star using the CARMENES radial velocity instrument has revealed TRAPPIST-1 probably isn’t a fluke. Two planets, similar in mass to the largest TRAPPIST planets, have been found orbiting in the inner and outer boundaries of the system’s habitable zone, and the lead authors believe there might be more. https://relay.nationalgeographic.com/proxy/distribution/public/amp/science/2019/06/two-potentially-life-friendly-planets-found-12-light-years-away-teegardens-star Teegarden b and c look very promising for both life and follow-up observations, but there are a couple of catches. The biggest: it doesn’t seem like either of these worlds transit. Even if they did, Teegarden’s Star is in the zodiac constellation Aries, and was not observed by NASA’s TESS mission. This will make accurate radius and composition measurements of the planets all but impossible, unless they do beat the odds and actually do transit, and a telescope like SPECULOOS or Spitzer is able to detect them. The other major catch is regarding where the planets are located in the habitable zone. Teegarden b, which is only 5% more massive than Earth, has an orbit of 4.9 days that gives it an insolation 1.14x Earth. This is well within the synchronous rotator inner limit of ~1.45 flux, which is caused by cloud cover forming on the day side of tidally locked exoplanets and helping them withstand higher insolations without going through a runaway greenhouse effect. However, the planet is rotating/orbiting so fast that dayside cloud cover won’t be able to form thanks to the Coriolis Effect. Teegarden b, therefore, finds itself in a similar predicament as TRAPPIST-1d, which can only be potentially habitable if its albedo is at least 0.3 (roughly the same as Earth, so it’s probably quite achievable due to 1d’s high water content). I assume this will be the same for Teegarden b. Teegarden c finds itself in the opposite situation: it’s near the outer edge of the habitable zone. In fact, it’s almost an exact twin of TRAPPIST-1f in terms of insolation (37% that of Earth), mass (1.11x Earth), and orbital period (11.4 days). It is well within conservative outer limits for the HZ and outside the 10-day inner limit where the Coriolis Effect starts to destroy dayside cloud cover. The one problem Teegarden c has is how low its insolation is. Combined with the likely cloud cover on the star-facing side, it’s a concerning possibility that the planet has ended up too cold to be Earth-like. This doesn’t exclude a Europa-like scenario, but it makes the planet somewhat less exciting. However, not all hope is lost. Teegarden c still has a lot going for it, and there is still a chance for Teegarden b to be conductive for life; it also has the highest ESI of any confirmed exoplanet at an impressive 0.95. Also, as I mentioned before, some of the authors believe there might be additional planets hiding around Teegarden’s Star, and it’s possible at least one of them is an even better potentially habitable planet than the ones we already know about. I think exoplanets similar in mass to TRAPPIST-1d or h could’ve been too small for CARMENES to detect and could be waiting to be found.
  10. Bad news: for some reason, I can’t downlod original Kepler data from MAST (the Mikulski Archive for Space Telescopes), so until I can fix that issue, I won’t be able to get to my KIC 12266812 analysis.
  11. I just re-calculated the parameters for the star and candidate using Gaia DR2 data and V and K magnitudes on ExoFOP, and the system looks even more incredible now. - Stellar Radius: 1.0095 (+/-0.0245)x Sun - Stellar Mass: 0.9935 (+/-0.0065)x Sun - Stellar Temperature: 5758 (+/-82) K - Luminosity: 1.00505x Sun - Semi-major Axis: 0.998102 AU - Equilibrium Temp: 255 K (the same as Earth!) - Insolation: 1.009x Earth KIC 12266812 and the planet candidate are just about identical to the Sun and Earth. Later today, I’ll take a look at the system with LcViewer and see if, maybe, there are other small planets in the system.
  12. I first heard about the game back in July/August 2014 before buying 0.90 at the end of the year. It wasn’t until a full year later — December 2015 — that I managed to finally update to 1.0.5, because I first got the game off of the original KSP website, not Steam. I still miss the planet-destroying double-claw glitch...
  13. I recently broke 800 hours on Steam. However, there were a good few weeks where I launched KSP from the file folder and not Steam, so who knows how much time I’ve actually clocked.
  14. 1.) The Clone Wars series 2.) Revenge of the Sith 3.) Solo 4.) Rebels series 5.) Rogue One 6.) A New Hope 7.) The Holiday Special 7.) The Empire Strikes Back 8.) Return of the Jedi 9.) The Mandalorian (when it comes out) 10.) Resistance Season 1 11.) The Force Awakens 12.) The Last Jedi 13.) Resistance Season 2 (when it comes out) 14.) The Rise of Skywalker (when it comes out) As you can tell, I’m a chronological order and animated series guy. I also wouldn’t really want to watch episodes I or II again, even though it has been years since I’ve last seen them.
  15. Updates to the stock planets? A surprise to be sure, but a welcome one.
  16. What would happen if you turn the knob on the Valve Guy’s head?
  17. I guess I should’ve worded it better. Yes, throwing your audience off guard is a great way to make a film more unexpected and interesting, but it depends on how you do it. You can either make it timeless like with the “I am your father” scene, or create more problems for how to continue the story.
  18. I don’t know what to say here that won’t get me torn apart by everyone who hates the sequels or TLJ or Disney-era Star Wars. I’m a very open minded SW fan, and it takes a lot for me to legitimately hate something. For example, I actually enjoyed TLJ. Did I agree with all the choices Rian Johnson made? No. Subverting audience expectations in the middle of a trilogy is a terrible idea and is just laying the groundwork for tons of people to get liquided off at you — which, as well all know, ended up happening. But do I let this ruin my viewing experience? Also no. The point is, I don’t let portions of a specific piece of Star Wars content ruin my enjoyment of said content as a whole, and I try not to get caught up on what I hate or disagree with, like so many other fans have with Disney-era films and shows (that includes all the Rebels hate because it’s not The Clone Wars, so to everyone who’s still like that after five years, just stop). This is where The Rise of Skywalker comes in. I’m keeping an open mind about it because I’ve been enjoying a lot of new canon content over the last few years, and I’m intrigued to see how J J Abrams repairs the trilogy from some of the poor plot choices from The Last Jedi. That doesn’t mean I’m not worried for a rehash of Return of the Jedi, especially since Palpatine and possibly Endor are making reappearances, but I’m hopeful that I’ll enjoy it. And time for this post to get ripped to pieces. Good thing the forums don’t have a dislike button, because I would probably be at -50 likes within an hour.
  19. While I don’t watch the films as often as I should be, considering how much of a Star Wars fan I am, I like almost all of them and would probably put Rogue One as my favorite. It’s the one I watch the most often, and it adds a ton of depth to A New Hope. That, and K-2SO may be one of the best additions to the new canon. It’s really hard to pick a second favorite out of A New Hope, The Empire Strikes Back, Return of the Jedi, The Force Awakens, and The Last Jedi (no you didn’t misread that). I’m still impressed at how well the original trilogy holds up after around forty years That said, I’m much more of a fan of the animated series — The Clone Wars, Rebels, and even Resistance. I’ve watched TCW since I was a kid and loved it ever since, and I’m hyped for the final season coming on Disney+. However, I enjoy Rebels a lot more. Don’t let Cosmonaut Variety Hour fool you, it’s a really good show, and I think it may be a little better than TCW. It may be a little rocky in the first two seasons, but the next two are almost consistently great, and the final seven episodes are some of my favorite Star Wars content ever. As for Resistance, it may be far from perfect as of now, but it shows great potential and I’ve actually be enjoying it so far. If you can’t already tell, I’m probably one of the most open-minded Star Wars fans out there. There are very few pieces of Star Wars content I legitimately hate; maybe about three or four total episodes from TCW and Rebels, and some scenes scattered across the saga, but that’s just about it.
  20. The discovery team ran some simulations and found that it is stable for at least 100 million years, and since the system is already 3.5 billion years old, it’ll be stable for even longer.
  21. Kepler-47, the first (and so far only) multi-planet circumbinary system around two main-sequence stars, just got a whole lot more interesting with the confirmation of a much larger third planet. https://www.space.com/amp/third-alien-planet-in-tatooine-system-kepler-47.html The new planet, Kepler-47d, is roughly 7 Earth radii and orbits every 187.4 days in the inner portion of the system’s habitable zone. That makes Kepler-47 the only system with TWO circumbinary habitable zone planets, a title that is probably going to be hard to beat. However, before anyone gets excited about potentially habitable exomoons, it should be noted that all three planets are extremely puffy — Kepler-47c could only be 3-5 times the mass of Earth despite being bigger than Neptune — so they probably aren’t massive enough to form or capture moons large enough to hold a significant atmosphere.
  22. Don’t forget Gliese 876. It has two gas giants in the habitable zone (one that’s twice as massive as Jupiter), along with a Uranus-like planet and a hot Super-Earth. I’m not too sure how so many massive planets formed around such a tiny star, but since we have yet to find another similar system after twenty years, I’m going to assume Gliese 876 is a rare oddball.
  23. Something tells me the Universe does not want any Center Core to be successfully recovered.
  24. Yeah...I can see why they don’t want to pull a Dumusque with this planet. Pretty coincidental that they’re both reported in the same star system.
  25. That’s pretty cool. If it does exist, I’m inclined to believe it’s a small gas planet due to its mass likely exceeding the 6 Me threshold for terrestrial planets (which is pretty irrelevant for planets around metal-poor stars as my research has found), and its large orbit keeping it safe from the stripping of its hydrogen envelope. If not, then it could be a frozen water-dominated ice world. I’m also pretty excited about the possibility of it being directly imaged. Because of its presumably greater radius and wider separation from a closer star, it’s a better target than Barnard b. What did he do? I don’t remember any recent discovery controversy, if that’s what you’re referring to.
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