clyde@reed.UUCP (Clyde Bryja) (08/26/85)
*** REPLACE THIS LINE WITH YOUR MESSAGE *** I'm looking for the most up-to-date information about the Sirius system. This includes almost every piece of data that can be known. Specifically: Parallax: I would like to know the BEST available measurement plus a standardly quoted uncertainty value. The best source that I have is the SKY CATALOGUE 2000.0 (Vol. 2), but I have a few reasons not to trust it too well (eg. I know that Kamper and Wesselink (1978) found a very definitive distance of 1.333 pc to Alpha Centauri whereas the SKY CAT. lists a parallax which translates to a distance of 1.326 pc). Orbital Period: BURNHAM'S CELESTIAL HANDBOOK lists 49.98 years, the SKY CATALOGUE (for the visual orbit) and the WEBB SOCIETY HANDBOOK (Vol. 1) list 50.09 years, and the SKY.CAT. also lists a spectoscopically observed period of 50.04 years. Which (if any) of these measurements is best? I would like the uncertainty quoted here as well. Masses: These are most important for my purposes, but are unfortunately (and not surprisingly) the most poorly known. B.C.H. lists 2.35 and 0.98 solar masses. The measurements from which Burnham computed the sum (3.33) of the masses are not at all in agreement with those listed in the SKY CAT. (which implies a value of 3.21 solar masses). Further, from the spectro- scopic mass function f(m) listed in the SKY CAT., along with the orbital inclination and the sum of the masses taken from the visual orbit, imply a mass for the companion of only 0.76 solar masses. I also remember a summer 1984 SKY & TELESCOPE article (I can't recall the month) that quoted the companion's mass to be 1.03 solar masses. Can somebody please help me here? I believe that I have good enough values for the other things that I want (orbital eccentricity, stellar diameters, semi-major axis of orbit, etc.), but if anyone knows of any recent improvements of any data pertaining to the Sirius system, I would appreciate hearing about them. Thank you very much for whatever effort you wind up putting into this (that includes just reading this article). -- +++++++++++ "For Easter Day is Christmas time, Clyde Bryja And far away is near, Box 21, Reed College And two and two is more than four, Portland, OR 97202 And over there is here."