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About ProtoJeb21

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    The Exoplaneteer

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  • Location EPIC 248435473 g
  • Interests Astronomy, planetary science/exoplanetology, entomology, meteorology (mainly tropical cyclones), Star Wars, Gravity Falls, drawing, data analysis, mathematics, and hiking.

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  1. Someone in my robotics club programmed their VEX robot to say “my battery is low, and it is getting dark out.” Their robot is also named F-bot, coincidentally enough, although I don’t think constantly playing a beloved rover’s dying message counts as paying respects.
  2. Looks like someone beat me to making that. Oh well. It’s much higher quality than anything I would be able to make. Rest in Pepperoni, Oppy.
  3. HD 48611 b I feel like it’s best to start off with a familiar planet to introduce the methodology used for all the systems I will (eventually) cover. A citizen scientist from Planet Hunters TESS, EEdiscoverer, is able to use a program called the Systemic Console to analyze archived HARPS radial velocity data to search for planets. It’s rather accurate and can provide some good estimates for the masses and eccentricities of the planets it’s able to detect. It is also very helpful for confirming TESS candidates around stars with old RV data that has been long forgotten. I will get to some of the RV systems EED has found this weekend, but for now I’ll be covering the TESS candidates that he managed to confirm. While he finds the masses of the planets, I use the latest TESS data from the Mikulski Archive for Space Telescopes (MAST) and LcViewer to get a better estimate for the planet’s radius. It turns out that many of my radius estimates over the last two years have probably been slightly over-estimated due to what’s known as the limb-darkening effect. In summary, the disk of a star is always brighter in the middle and dimmer at the outer edge, and this influences the estimate for a transiting planet’s radius, decreasing it slightly most of the time, unless it has an orbit that just skims the disk of the star. I took this effect into account when analyzing these TESS candidates. With the procedure finally out of the way, it’s time to talk about what we found. My radius results varied depending on how many data points I allowed to be generated in the light curve. 30 per hour often started to “blend in” the transits, so I later went with 6 per hour. Taking into account limb darkening and the uncertainty of the planet’s transit duration, I found the radius of HD 48611 b to be about 1.67 (+/-0.10) R_Earth. This is within the Fulton Gap, a range of planetary radii from 1.6 to 2.0 R_Earth where planets are less common because they’re transitioning from rocky Super-Earths to puffy Mini-Neptunes. Therefore, HD 48611 b should have a mass compatible with a rocky composition and a thin water layer, right? Nope. The Systemic Console’s best fit for the RV data of HD 48611 was a planet 8.39 times the mass of Earth with an orbital eccentricity of 0.2791. That puts the planet’s density at a hefty 9.9 g/cm^3, and a surface gravity of almost exactly 3 gees. The results provided by EEdiscovere, along with my transit analysis, suggest HD 48611 b is a rare high-density Fulton Gap planet compatible with a relatively iron-rich composition and NO significant volatile layer (hydrogen, helium, water vapor, methane, or other heavier gases). The planet’s core could take up 45-60% of its entire mass — that’s an iron core as much as five times the mass of Earth! This is at odds with current theories about the Super-Earth/Mini-Neptune transition. So, why is HD 48611 b so dense? One may first assume a giant impact like Mercury or the recently characterized Kepler-107c (which is even bigger at almost ten Earth masses), but the answer is much simpler: the star is metal-poor. HD 48611 contains only about 43% as much metals, or any element heavier than hydrogen or helium, as our own Sun. While at first the formation of a giant rocky planet around such a host seems unlikely, it’s the complete opposite, because forming planets around metal-poor stars take too long to get large enough to accumulate thick volatile layers. By the time most have reached this size limit, the original hydrogen disk has been blown away by stellar radiation, leaving mainly heavier materials left for the new planets to feed on. Also, since no other planets have been found, and since it has an unusually eccentric orbit, it can be assumed that HD 48611 b consumed all the forming planets in the inner system when it was young, allowing for it to accumulate such a high quality of rock and iron. But just when this planet was figured out, the Universe decided it wasn’t done being weird. It turned out HD 48611 b was just the tip of the iceberg for unusual density TESS planets, and some would be even more extreme with an even more violent past. I promise that I will present these systems as soon as I have an hour or two to do so.
  4. Either later tonight or tomorrow, I will make my post on K2-288 Bb, as well as several new TESS systems I’ve helped characterize. These have been confirmed via radial velocity and transit data, so decent estimates on their compositions are available. These will include an update on HD 48611 b and the HD 23472 system, as well as a few RV-only systems found by a citizen scientist on Planet Hunters TESS. EDIT: scratch that, I just realized my schedule is literally packed to the max until Saturday night. I may be able to get one system out tonight and save the rest (including Space Engine renditions of them) for this weekend.
  5. ProtoJeb21

    Do you think Tau Ceti e is inhabited?

    I’m going to say no. Tau Ceti e has too many problems and is only a fair candidate for potential habitability at best, for several reasons. 1.) It may not be rocky. While it has a minimum mass of just under four Earths, if the planets are on the same inclination as the debris disk, then Tau Ceti e is somewhere around 7-8 Earth masses. Most rocky planets are no more than 5-6 Earth masses, and at that mass, Tau Ceti e has a greater chance of being a small ice giant. However, there is hope for it. Tau Ceti is very poor in metals, or any element heavier than hydrogen and helium. This actually facilitates the formation of rocky planets because it takes so long for them to form. By the time they’re big enough to start accumulating large layers of volatiles, the hydrogen in the planet-forming disk is all but blown away by the star. So there is a chance Tau Ceti e is rocky, maybe similar to the 7 Earth mass terrestrial habitable zone planet LHS 1140 b. 2.) Even if Tau Ceti e is a rocky planet, there is one huge problem that could kill its chances for hosting life: the amount of sunlight it gets from its star. The planet receives an insolation about 80% higher than Earth, which may not seem like much, but is slightly less than that of Venus, which is in no way habitable. Tau Ceti e, therefore, has dangerously high odds of being a hellish Super-Venus with a runaway greenhouse effect and no surface water. But like before, there might be a way for things to work in this planet’s favor. If it’s tidally locked — which isn’t too unlikely at its orbit — then it could survive insolations as high as 2.2 times that of Earth. However, this probably isn’t the case. 3.) If Tau Ceti e somehow beats all the odds and is not only rocky but hasn’t turned into a Super-Venus, one more challenge remains. I mentioned before that there’s a large debris disk in the system. That is bad news for the potential habitability of any Tau Ceti planet, because that disk contains around ten times more asteroids and comets than are in our Solar System. This means that Tau Ceti e, f, and any possible undiscovered habitable zone planet would be frequently struck by space debris, disrupting the peace and stability needed for complex life to evolve. If life did miraculously get a foothold on Tau Ceti e, there’s a good chance it has since been wiped out. So despite all the hope that the Tau Ceti solar system is something like in Star Trek, I highly doubt that is the case. Is it still interesting and worth continued observations and studies? Absolutely. Is it one of the best potentially habitable nearby systems? Absolutely not. I put my bets on Luyten b or LHS 1140 b having at least some form of life, since both are well within their systems’ habitable zones, orbit very quiet red dwarfs, and are likely rocky (the latter actually is confirmed to be terrestrial).
  6. ProtoJeb21

    Weather Chat Megathread

    59-61 F has never felt so nice. After the below-freezing temperatures over the past few weeks (with a few days getting at little over 32 F/0 C), anything around 40 F is more than welcome, and 60-63 F highs for two days in a row is an absolute blessing. Too bad it’s going to return to normal February temperatures starting tomorrow.
  7. Something like that with two ocean worlds is impossible — the planets would tear each other to pieces or collide, depending on the mass ratio between the two. However, this “shared fluid” binary scenario has been seen with closely orbiting stars, where they are so close to each other that they share some of their plasma envelopes.
  8. I don’t think so. At least, nothing has been published yet. It’ll probably take several more months at least before we get something.
  9. Sorry I didn’t do a dedicated post about K2-288Bb, and that I haven’t been around very often. I’ve been trying to sort out some things about K2-288Bb and find some more planets, while also analyzing a few TESS exoplanet candidates and preparing for other things that I’ll post about once they’re finished. Since it’s been a month now, I will finally make my K2-288Bb overview post and present some very interesting finds from Planet Hunters TESS, including multiple using the radial velocity technique. Stay tuned!
  10. ProtoJeb21

    Lunar Eclipse January 20-21 2019

    The aftermath of Winter Storm Harper has made it hard to predict whether or not it’ll clear up in time for the eclipse, but as of now, it seems like it is clearing and will stay (mostly) clear. I wonder how the moisture in the atmosphere will impact how red the moon gets from my vantage point, since low moisture and high levels of dust are known to make it darker red.
  11. ProtoJeb21

    Weather Chat Megathread

    Winter Storm Harper wasn't a big snowmaker for where I live, but it glazed EVERYTHING in ice, which has made for some really cool photography opportunities.
  12. ProtoJeb21

    Weather Chat Megathread

    You’re lucky. I’m not too sure if the sky will clear up quickly enough for me to see the Moon when it’s in the umbra.
  13. ProtoJeb21

    Weather Chat Megathread

    10 F is the actual temperature; I don’t know the exact wind chill prediction for Monday, but I’ve been hearing around -20 F. Do you live in New England as well?
  14. ProtoJeb21

    Weather Chat Megathread

    It’s lucky that it’s still even somewhat active after over two years. I’m also getting stuff from Winter Storm Harper, but not much. Likely 3-5”, maybe 5-8” if I’m lucky. However, temperatures will drop to no more than 10 F for Monday, and it may clear up quick enough Sunday night to see the total lunar eclipse.
  15. R/Prequelmemes: “r/StarWars just circlejerks in whatever is the thing that mean Disney Is Evil, without looking into what the facts actually are”. Look who’s talking. (And yes, that is an actually quote from Prequelmemes just a few days ago after everybody went berserk over Warner Chapell copyright striking that Vader fan film because they thought it had copyrighted music. Jeez, people need to calm down.)