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Exoplanetary Scratchpad

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  • Kepler-186 System [One of the oldest known Earth-like planets. Featuring lush vegetation in the game world.] - An M1 red dwarf found by Kepler to have five rocky planets. These planets are labelled b through f as you go further out. The smallest one, b, is only 8% larger than the Earth and the largest one d is 40% larger. The inner four are tidally locked, but possibly not the outer one. There might be one additional non-transiting planet inside the furthest one's orbit. The outermost planet f is the first Earth-sized planet found in the habitable zone and currently the smallest known Red Dwarf planet in the habitable zone. The planet does not receive as much heat as most PHPs though, so it is ranked low on the ESI.
  • Alpha Centauri System [Orbiting the closest star to our solar system.] - Alpha Centauri is also known as Rigil Kentaurus. A is also known as HD 128620 and HR 5459, B is HD 128621 and HR 5460, and C is Proxima Centauri. It is the nearest star system to the Sun. Contains a yellow dwarf star a little bigger than the Sun and an orange star a little smaller orbiting each other orbiting each other about the distance Uranus is from the Sun (varies from Saturn like to Neptune like), as well as a distant Red Dwarf companion Proxima that may or may not be orbiting the other two.

    Stellar fingerprinting suggests a high probability that a planet orbits star A, due to dearth of Iron around star. Russian astronomers announced the detection of a second planet orbiting the binary pair at 80 AU with a 100 year period, which appears to be false. The stars in the system will become markedly closer together in 2016, making observations much more difficult and one follow up failed to find it. The system is the first target for the European Cheops exoplanet space telescope.

    A planet was thought to have been discovered around star B and detected by HARPS. It would have been an Earth-massed rocky-iron planet with no atmosphere at epistellar distances around the orange dwarf star B. This would have been the least massive planet found around a sunlike star. The planet was informally and controversially named by Uwingu during a fund raising naming contest Albertus Alauda, after a participant's grandfather. Earthlike planets are not detectable in the habitable zone with present radial velocity methods. Technique for detection of planet is a source of doubt for some and it has yet to be independently verified. A team thought they might have detected a transit of this planet, but further observations showed the timing wasn't consistent. It is possible that a second further out (20.4 day period) Earth-sized planet is altering the transit times of the first. A cheap crowdfunded satellite devoted to studying this star could confirm the planets. The star was observed to be a good candidate to host a "super Habitable" planet, which would have 25% more gravity than the Earth, shallow seas, flatter landscape, higher atmospheric pressure, and the 6 BYO star would be stable for life longer.

    Proxima, a small flare star, was discovered in 1915 by Robert Ines, who named it. Long suspected planet around Proxima found not to exist. The Pale Red Dot project is dedicated to finding a planet around Proxima using dopplar spectrometry. As Proxima passes in front of two stars (once in 2014, again in 2016), any planets within 5 AU should be detectable via microlensing using the HST. It is known that no planets of Neptune sized mass exist within 1 AU and no Jovians with periods up to 1000 days, or transiting planets exist. An Earth-like planet in the habitable zone was discovered around Proxima Centauri. In 2017, a large stellar flare erupted and bombarded the planet, making it likely that the atmosphere has been completely stripped away by events such as this and not a good candidate for life. It was thought that a lot of dust existed in the system, making it feasable that the star had a rich complement of planets, but this seems to not be the case.

  • Tau Ceti System [A planet of seas and archipelagos.] - Tau Ceti is also known as HD 10700, HR 509, and Gl 71. The nearest single G-class yellow dwarf to the sun, somewhat smaller than the Sun. A popular science fiction subject and one of two targets of SETI-forerunner Project Ozma in the 1960s. Despite being somewhat older than the sun, it has an extensive asteroid and/or comet field 10-50 AU, with the bulk between 35 and 50 AU. It has about ten times as much material as the Sun. This would make life difficult. It is a metal deficient star, so it is thought less likely to host rocky planets. Traditional dopplar spectrometry has ruled out any large Jupiter sized planets at Jupiter like distances or closer in, which was thought to be good for any potentially habitable planets. Five candidate rocky super Earth planets were detected though using a new method of planetary detection. This method made predictions of the stellar "noise" activity that might obscure detection of a planet based on the long history of dopplar measurements done on this system. Deviations from this prediction pointed towards the existence of planets. Confirmation using more established methods is needed. These planets are labeled b through f as you go outward, span 0.1 AU to 1.35 AU, and get larger the further you go out (at least 2 ME to 6.6 ME). The outermost two are near the habitable zone and were originally hailed as possibly being the nearest and smallest known habitable planets. More recent modeling indicates they are not actually habitable though. Planet e is probably too close to the star and only in the HZ if generous assumptions are made. Planet f has probably only been in the habitable zone for about a billion years as a result of its star becoming hotter, which might make biosigns difficult to detect from Earth, considering it took 2 BY for biosigns to become detectable around the Earth. Since the star has a higher magnesium to silicon ratio than the Sun, these planets compositions could be quite different that the Solar System's. The lower mantles could be dominated with ferropericlase, which is not very viscious, which may make the rocks of the mantle flow easier than on Earth, affecting volcanism and tectonics. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
  • Mu Arae System [Tidally locked in orbit around a weak star, half the planet is frozen while the other half is always hot.] - Cervantes (Mu Arae) is a 6th magnitude Sunlike star close to becoming a Sub-Giant located 50 ly with four known planets. At first believed to be a system dominated by orbit crossing eccentric Super Jupiters. Instead, three Jovians orbit in roughly circular orbits at Earth-like (Rocinante, d), Mars-like (Quixote, b, in habitable zone), and Jupiter-like (Sancho, e) distances in addition to an inner (Dulcinea, c) Hot Neptune. Planet c was one of three Hot Neptunes or Hot Super Earths discovered around the same time. It was the first one announced, but it was still under scientific review at the time, so there remains controversy on what the actual first planet discovered of this class is. Initially thought to likely to be rocky because it had 2 known neighboring gas giants which may have stunted its growth. The characteristics of the planets in this system changed greatly as new planets were discovered, and included a re-ordering of their designations. Initially, the first planet b was thought to be highly eccentric. An outer planet was then detected, at the time dubbed "c" (though a full period hadn't yet been observed), and was thought to have an extremely high eccentricity so that the orbits of the two planets would cross. An innermost third planet then dubbed "d" was then detected. A new fit for the data then emerged, and it was found that the outermost planet was actually much less eccentric, and that there was a planet interior to planet b with almost half its period. The eccentricity of b was also reduced so that no planet criss-crossed another's anymore. It was decided to redesignate the planets in order of characterizations instead of by discovery, so the innermost Neptunian planet was re-dubbed "c" and the planets just interior and exterior to planet "b" were re-dubbed "d" and "e". The system became the second known 4-planet system. The innermost two Jovians are close enough so that they're unstable over short periods of time. If they were actually in 1:2 resonance, which almost fits the data, they would be much more stable. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Star is named after the author of Il Ingenioso Hildalgo Don Quixote de la Mancha and the planets after its characters, Quijote (main character), Dulcinea (love interest), Rocinante (horse), and Sancho (squire).
  • 82 G. Eridani System [Tectonically unstable.] - 82 G. Eridani is also known as 82 Eri, HR 1008, Gl 139, and HD 20794. One of the nearest star systems with planets. It is one of the dimmer yellow dwarf stars. Has three radial velocity detected super Earth planets orbiting closer than the habitable zone. The outermost one d is the largest (5 times Earth's mass, twice its radius, rocky-water composition) is about the same distance as Mercury is from the Sun. The middle one c is 0.1 au closer and is the smallest (2.5 Earth's mass, 1.5 its radius) and is likely a rocky-iron in composition. The innermost one is at 0.1 AU and just slightly larger than c, but more massive and of a more rocky-water composition. A dust disk was also found about 20AU from the star. The 2007 book "Habitable Planets for Man", released prior to the discovery of the planetary system, placed this as the most habitable star system within reach of mankind.
  • Eta Vulpeculae System [A mysterious new discovery with unknown terrain.] - Eta Vulpeculae System

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