Since Alcyone has a proper motion or drift of 6" per century, this means that all the brightest stars except the eight mentioned are drifting with Alcyone and so form a true cluster, at approximately the same distance from the earth.
It has been found that on an average the parallax of a star is about one-seventh of its "proper motion.
The largest "proper motion" now known is that of a star of the 8-1/2 magnitude in the southern hemisphere, known as Cordoba Zone V.
Should, however, the result from any one of these stars differ considerably from that derived from the rest, it will be due in all probability to that star having a proper motion of its own, and it may therefore be rejected.
A vast mass of observations as to the place of Sirius among the stars had thus been accumulated, and it was found that, like many other stars, Sirius had what astronomers call proper motion.
We are brought thus to the very heart of the matter; parallax, proper motion, and motion in the line of sight are intimately related quantities, all of which are essential to a knowledge of the real motions of the stars.
This discovery, long since fully confirmed, gave a great impetus to observing with all possible accuracy the right ascensions and declinations of the stars, with a view to finding other cases of what was called proper motion--i.
In the astronomical literature of the last century we find the star 1830 Groombridge designed as that which possesses the greatest known proper motion.
From the positions of a star on two or more occasions we obtain its apparent motion, also called the proper motion of the star.
The same has been proved for proper motion, and line of sight motion, in the case of Pleiades and other groups.
It has often been noticed that stars which seem to belong to a group of nearly uniform magnitude have the same proper motion.
So we find parallax, proper motion, double stars, binary systems, variable stars, and new stars all bound together.
These appearances may be partly due to a proper motion; but, so far as it went, this was a beautiful confirmation of Wilson's discovery.
The well-known double star 61 Cygni has a proper motion of about five seconds of arc per annum, both components moving through space together.
The remarkable triple star 40 Eridani has a proper motionof four seconds annually.
The largest "proper motion" hitherto detected (about seven seconds of arc per annum) is that of a small star in the constellation Ursa Major, known to astronomers as No.
The above list will hopefully provide you with a few useful examples demonstrating the appropriate usage of "proper motion" in a variety of sentences. We hope that you will now be able to make sentences using this group of words.
