Group Members
Current criteria for membership in the moving group is based on the stars' motion in space. This motion can be determined from the proper motions and parallax (or distance) to the stars and radial velocities. The Hipparcos satellite has recently greatly improved both the proper motion and parallax estimates of nearby bright stars, refining the study of this and other moving groups .
Based on their distances (measured with Hipparcos) and apparent magnitude, the absolute magnitude can be used to estimate the age of the stars. The stars in the moving group appear to have a common age of about 500 million years.
Read more about this topic: Ursa Major Moving Group
Famous quotes containing the words group and/or members:
“Now, honestly: if a large group of ... demonstrators blocked the entrances to St. Patrick’s Cathedral every Sunday for years, making it impossible for worshipers to get inside the church without someone escorting them through screaming crowds, wouldn’t some judge rule that those protesters could keep protesting, but behind police lines and out of the doorways?”
—Anna Quindlen (b. 1953)
“The members of a body-politic call it “the state” when it is passive, “the sovereign” when it is active, and a “power” when they compare it with others of its kind. Collectively they use the title “people,” and they refer to one another individually as “citizens” when speaking of their participation in the authority of the sovereign, and as “subjects” when speaking of their subordination to the laws of the state.”
—Jean-Jacques Rousseau (1712–1778)