Everything in the universe is in constant motion, even the stars themselves. Yet the stars are so far away that the constellations of the night sky seem to be essentially unchanging. But, everything is moving.
The various motions of the stars and our own Sun through space can make the nearby stars appear to change their positions relative to more distant background stars. Alas, none of these are the stars that shine brightly in our sky.
61 Cygni is a binary star that is 11.4 light years distant and can faintly be seen under dark skies. The two stars of the 61 Cygni system are a little smaller and cooler than the Sun. They take over 600 years to orbit about each other.
I used my Unistellar eVscope to take an image of this system in September 2021 and again earlier this week. As you can see in the image below, this system of two stars is indeed moving relative to the more distant background stars:
This is motion known as 'proper motion' and, I confess, wasn't something that I thought I would be able to see, because I hadn't actually given it much thought and I am happy to know that for the right stars this is pretty easy to observe. The main thing needed (other than the telescope & camera) is time.
61 Cygni isn't alone in having a high proper motion. Other stars have it too. One of them is known as Lalande 21185. It is a red dwarf star located just 8.3 light years from Earth, but it is too faint to be seen without a telescope. Here's an image from June 2021 blinked with one from earlier this week:
Finally, here's the star with the highest proper motion: Barnard's Star:
Like Lalande 21185, Barnard's Star is a cool red dwarf star that is too faint to be see without a telescope. It is located just six light years from Earth.
There are other stars that are near to us that have high proper motions and I'll be spending some of my evenings looking to see if I can catch them as they move through the skies.
No comments:
Post a Comment