Procyon A and B |
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Procyon A is a main sequence star which is a little larger and consequently hotter and faster burning than the Sun. It is 7.5 times a bright. Procyon appears to be relatively young - about one third the age of the Sun. Known as the 'Little dog star" it rises before Sirius and is the eighth brightest star in the sky. Procyon B is a white dwarf with 60% the mass of the Sun that is slowly cooling to yellow and appears to be older than Sirius B. Procyon B is very faint and was not identified visually until 1896. The two stars orbit their mutual center of mass in elliptical orbits with a period of 40 years. The stars are on average separated by the distance from the Sun to Saturn. It is thought that Procyon B was once a very large hot main sequence star that moved off the main sequence long ago and in the process enriched Procyon A with heavy elements as it became unstable and threw off its outer layers as a planetary nebula. The present white dwarf is the cooling remnant of the core of that star. |