恒星的形成与演化2.ppt

超新星出现率.h是哈勃常量,单位是72km s-1 Mpc-1 * * * NASAs Hubble Space Telescope captures a small section of the Cygnus Loop supernova remnant. The Cygnus Loop marks the edge of a bubble-like, expanding blast wave from a colossal stellar explosion which occurred about 15,000 years ago. * * Sections in the orbital plane of the Roche equipotentials for a binary system with mass ratio m2/m1=0.25. The eqipotentials are labeled 1-7 in order of increasing potential. L4 and L5 (the “Trojan asteroid” point) are local maxima of Roche potential bur Coriolis force stabilizes synchronous orbits of test bodies at these points. * Sections in the orbital plane of the Roche equipotentials for a binary system with mass ratio m2/m1=0.25. The eqipotentials are labeled 1-7 in order of increasing potential. L4 and L5 (the “Trojan asteroid” point) are local maxima of Roche potential bur Coriolis force stabilizes synchronous orbits of test bodies at these points. * * * * * * * * * * * xkong@ * 昴星团Pleiades 疏散星团 * xkong@ * 球状星团 * xkong@ * 47 Tuc – SALT optical * xkong@ * 47 Tuc – Chandra X-ray * xkong@ * Cen –Kitt Peak * xkong@ * ? Cen - HST * xkong@ * M5 – optical * xkong@ * M5 Colour-Magnitude Diagram MS Main Sequence TO：Turn-off RGB：Red Giant Branch HB：Horizontal Branch “gap” RR Lyraes AGB：Asymptotic Giant Branch * xkong@ * * xkong@ * 星团演化的模拟结果 Birth 8×106 yr 3×109 yr 256×106 yr 8×109 yr * xkong@ * Temperature-luminosity ： L ~ Teff? where: ?~0.4 Mass-luminosity L ~ M? where: ? ~3.5 Our theory of stellar structure must reproduce both these results Some observational facts SELF-TEST: TRUE OR FALSE? All the red dwarf stars that ever formed are still on the main sequence today. Once on the main sequence, gravity is no longer important in determining a stars internal structure. As a star evolves away from the main sequence it gets hotter. A planetary nebula is the disk of matter around a star that will eventually form a planetary system * xkong@ * SELF-TEST: TRUE OR FALSE? For a high-mass star