I’ve been working on a system for randomly assigning classifications to stars with something like real-world distributions. I haven’t quite got it right yet. So I’ll just pick something out based on my current obsessions. Yaccatrice will orbit an M-class star that suffers from occasional flares. Unlike many small red flare stars, this one will be fairly sedate. While it would be interesting to consider the climate of an otherwise earthlike planet that suffered a doubled insolation for a few days at a time every few years, I’m not sure a planet could survive the ozone-destroying x-ray output of such flares occurring very often.
After playing around a bit looking at the Padova site and the table in the back ofWorld-Building, I chose a mass of 0.3MSol and an age of about 8 billion years. I used the CMD to create isochrone tables with a metallicity of Z=0.1220. I went down the table to a log(age/yr) of 9.9, which represents an age of 7.944 billion years, close enough to eight, and an M_act of 0.3000MSol. From that chart I got a luminosity of 0.0142LSol(raise 10 to the power of the value under the heading
LogL/Lo), and an effective surface temperature of 3,736K(raise 10 to the power of the value under the heading of
logTe)(I’ll round the temperature to 3,700K ’cause I’m already enough of a douchebag…:)). Now, using the observation that luminosity is proportional to the square of the star’s radius and the fourth power of the star’s effective surface temperature (
L/LSol = (R/RSol)2*(T/TSol)4) and a modicum of algebra(remembering that the Sun’s temperature, TSol = 5,778K), I can determine that the radius of Yaccatrice’s star is
R/RSol2 = (L/LSol) / (T/TSol)4 or
R = 0.285RSol(198,531 km). Looking again at the table in World-Building, I figure that the temperature falls between the temperature for an M0 star and the temperature for an M2 star. Let’s call our star M1V for an M1 main-sequence star. There is our information on the star, which I’ll name Cintila.
Tomorrow we will be looking at the positions of the planets orbiting Cintilla. This will be based in part on some basic assumptions about Yaccatrice.
Thank you for your attention,