The proper motion of 61-Cygni at one year intervals.
Parallax method, 61-Cygni and the Hipporcas mission
It is trivial for most astronomy textbooks to illustrate the parallax method as follows:
This is absolutely fascinating, but it was really hard to find actual images of stars in books that illustrate this.
This is the proper motion of 61-Cygni, a binary star system over a span of couple of years.
But Bessel discovered that in addition to this proper motion, 61-Cygni also wobbled a little bit from side to side because of the parallax during observation.
The following is a plot of the motion of 61 Cygni – A which beautifully elucidates the proper motion and the effect of parallax (i.e the wiggle of the blue line with respect to the mean free path)
In addition, if you would like to actually play around with data for yourself, the The Hipparcos Space Astrometry Mission might interest you a lot. The mission was Launched in August 1989 and successfully observed the celestial sphere for 3.5 years before operations ceased in March 1993 employ
The documentation and the catalogue are fairly clear , instructive and easy to use. Have fun!
- Video – 61-Cygni and it’s importance
- More proper motions of stars animations can be found here.
- 1838: Friedrich Bessel Measures Distance to a Star