{ "export": { "source": "https://urth.darkrealm.vip/thread/urth/2508", "note": "Exported from an unofficial mirror of a public mailing list. Copyright in each message remains with the person who wrote it. Email addresses are obscured as `user at host`, the form the original archive published. This file was rebuilt from parsed fields rather than retained headers, so it is faithful in content but not byte-exact.", "addresses": "obscured as 'user at host'" }, "archive": "urth", "thread": { "id": 2508, "subject": "If You're Going to Ste. Anne, Be Sure to Pack a Sweater", "messages": 1, "voices": 1, "first": "2000-12-14T23:51:28+00:00", "last": "2000-12-14T23:51:28+00:00" }, "messages": [ { "message_id": "", "from": { "name": "Talarican", "address": "exultnttalarican at mindspring.com" }, "date": "2000-12-14T23:51:28+00:00", "subject": "(urth) If You're Going to Ste. Anne, Be Sure to Pack a Sweater", "in_reply_to": null, "reply_link": null, "blocks": [ { "kind": "text", "depth": 0, "text": "HARD SCIENCE ALERT! SENSITIVE PERSONS TAKE COVER!\n\nSte. Croix / Ste. Anne's (hrta \"C&A\") year is simply not likely to be longer\nthan that of Earth, such as Mantis' 1.23 Earth years. On the contrary, it\nshould be considerably shorter. Given that C&A's sun (hrta \"C&AS\") is\nundeniably redder and cooler than Sol, and humans apparently live quite\ncomfortably on the planets without any technological life support, these\nobservations do not fit together within conventional astrophysics.\n\nFor C&AS to be noticeably redder than Sol implies that it is of a cooler\nspectroscopic type such as K or M, as opposed to Sol's G (the Sol of your\nday, not my Old Sun), which means it must also be either a lower-mass,\nsmaller main sequence star than Sol, or a red giant. I think we can rule out\nred giant almost immediately. An orbit of period 402 days would put the\nplanets well within the star's radius, or at least very close. Red giants\nare shortlived and rather unstable, with a lifetime of around a billion\nyears or less. There would not have been time for a previously frozen outer\nworld to evolve complex life in the manner of Earth after the star hit red\ngiant stage. Also, I think someone would have remarked on the fact that the\nsun filled half the sky, had it been so.\n\nTherefore, C&AS is a main sequence star considerably cooler than Sol. It\nfollows the star must be less massive and somewhat smaller than Sol. While\ndecreasing the mass increases the orbital period (the square of the period\nis inversely proportional to the star's mass), decreasing the size and\ntemperature of the star drastically reduce its luminousity. Exobiologists\nwrite of a star system's \"habitable zone\", that range of distances within\nwhich a terrestrial planet might be expected to have liquid water on its\nsurface. (some have remarked that that is too liberal a range of\ntemperatures) Since luminousity decreases as the square of the diameter and\nas the temperature to the fourth power, and since the energy reaching an\norbiting planet decreases with the square of the distance, the \"habitable\nzone\"'s radius and range is quite sensitive to, ultimately, the mass of the\nmain-sequence star. Therefore, a world habitable for life-as-we-know-it must\nbe much closer to a less massive star.\n\nFor example: Tau Ceti, still a very sunlike type G star, has about 82 to 90%\nsolar mass. Its luminousity is only 59% that of Sol! Therefore the middle of\nits \"habitable zone\" is only 68% as far out as the Earth's orbit from Sol\n(i.e., the center of Tau Ceti's habitable zone is 0.68 astronomical units or\na.u., from the star), and the orbital period of an object in that orbit is\nabout 228 days. And Tau Ceti probably would not be distinguishable from Sol\nto a casual observer on the hypothetical planet's surface.\n\nEpsilon Eridani, a type K star whose temperature is about 4900K to Sol's\n5800K, and whose mass is about 0.8 solar, has been the subject of much\nspeculation about the possibility of planets and life, due to a noticeable\ndust ring. Its luminousity is about 0.34 Sol's. Its habitable zone is about\n0.54 a.u, period 172 days. An observer might notice the sun being somewhat\nmore red-orange.\n\nRobert Borski and Mantis have previously suggested that C&AS might be Wolf\n294, a type M star in Gemini. While Cave Canem offers some intriguing\nreasoning, and the color might be right, a type M star seems far-fetched. I\nlack statistics on Wolf 294, but Luyten 726-8 AB seems to be a near-twin.\nIts mass is 0.12 solar, and its luminousity is about (pause, catch breath)\nsixty one-millionths solar. The habitable zone lies cozily against the\ngently glowing star at 0.0075 a.u. which I believe is a little over twice\nthe average distance of Lune from Urth? A planet that close would tide-lock;\nI don't think a pair of co-orbiting planets could be stable.\n\nConclusion: Given red star, given humans going practically naked, a 1.23\ntimes as long year is quite unlikely. C&S would not be habitable for humans\nwithout technological life support. Therefore, some other interpretation of\nthe clues in the text is in order.\n\nI am still awaiting delivery of my used copies of 5HC (1 Scribner's, 1 Ace)\nfrom that emporium called, in one of your dead languages, \"Lacking Breast\".\nThe oddities of your language and culture provide me endless puzzlement and\namusement. When I have those tomes, I can search for more evidence.\n\nP.S. Mantis \"artificial-seeming age/decay of the buildings on Ste. Croix\"\nas evidence that clumsy abos incapable of maintaining them are in charge! (I\nwonder if the Veil Holocaust took place at my alma mater, too?) A worthy\nargument, I salute you, but I must point out, not quite conclusive; there\nare other explanations for poor building maintenance, especially in a rather\ndecadent culture. Could the early colonists have wished to create a more\nhomelike atmosphere with a faux European pseudo antiquity?\n\nThe Mad Exultant" } ] } ] }