Chronology |
Current Month |
Current Thread |
Current Date |

[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |

*From*: "Karshner, Gary" <gkarshner@stmarytx.edu>*Date*: Fri, 14 Sep 2012 21:38:03 +0000

Bill,

One of the ways of measuring distance to stars is to use the astronomical parallax. The apparent shift in position of a star as it orbits the sun. The reciprocal of this measured in seconds of arc is the distance in Parsecs. The largest parallax is about 3/4 of a second of arc or a distance of 1.3 parsecs. So no star is within a parsec and most parallaxes are far smaller than this or the stars are much further away. Using 10 parsecs is thus a compromise and big enough to include all stars except the sun.

Hope this helps.

Gary Karshner

St. Mary's University

-----Original Message-----

From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Bill Nettles

Sent: Friday, September 14, 2012 3:09 PM

To: Phys-L@Phys-L.org

Subject: [Phys-L] absolute magnitude

I've done some searching, but obviously not in the right places:

How did astronomers arrive at 10 parsecs as the distance used for computing absolute magnitudes?

Bill Nettles

Union University

_______________________________________________

Forum for Physics Educators

Phys-l@phys-l.org

http://www.phys-l.org/mailman/listinfo/phys-l

**References**:**[Phys-L] absolute magnitude***From:*Bill Nettles <bnettles@uu.edu>

- Prev by Date:
**[Phys-L] absolute magnitude** - Next by Date:
**Re: [Phys-L] absolute magnitude** - Previous by thread:
**[Phys-L] absolute magnitude** - Next by thread:
**Re: [Phys-L] absolute magnitude** - Index(es):