|Designations:||V645 Centauri, HIP70890.|
|Diameter:||8.48% of the Sun.|
|Distance:||4.24 light years.|
|Image date and exposure:||25th August 2020. 10 x 30 sec.|
|Field of View:||47.8 x 31.7 arcmin; up is 174° E of N.|
Triple Star System
Proxima Centauri is understood to be in a wide orbit around the binary system, Alpha Centauri A and Alpha Centauri B, two Sun-like stars which orbit each other.
It’s hard to grasp that it is currently more than 2° 11′ from Alpha Centauri.
Proxima lies about 15,000 Astronomical Units (0.2 light years) from the much tighter orbits of the binary pair and if its membership of the Alpha Centauri System is verified, it’s orbital period would be about a million years.
The Alpha Centauri system is the closest star system to our Solar System and of its three stars, Proxima is currently the closest – a mere 4.24 light years away from us. It only looks bright in the image because it is much closer than the other more remote stars.
Despite it’s proximity to us, Proxima is a very tiny faint type M star, a red dwarf, located in a star-rich region of the Milky Way – and it moves. So it is difficult to pin down.
Tracking it Down
During the execution of the imaging, I could not be certain which of the many stars on my monitor represented the target. It was fun tracking it down with a spot of research the next day.
The best planetarium software I have (Sky Safari Pro v6) only displays about half of the stars shown in my image. At least it does show Proxima and after an hour of comparing the star patterns around Proxima in Sky Safari with the many stars in my image, I tracked down the exact spot where it was supposed to be.
There was nothing there! 😨
Proxima has an apparent motion of nearly four arc-seconds per year, which is a lot, so I checked the settings in Sky Safari and sure enough, whilst it was correctly displaying Epoch J2000.0, the “Proper Motion” box was not selected. As soon as I ticked it, Proxima disappeared and reappeared about 77 arc-seconds away.
Back to my image and “bingo”, there it was!
Never before have I had to worry about a star’s proper motion. So, based on a reverse image of my photo, here is the motion of Proxima from 1980 to 2020:
Proxima’s motion over forty years reminded me of the motion I “discovered” when I imaged dwarf planet Pluto twice in eight days – but Pluto was only 30 AU from the Sun. For context, Proxima is about 266,840 AU from the Sun.
- According to Wolfram Alpha, whilst light from Proxima takes 4.2 years to reach us, it would take 6.3 years if travelling that distance by optical fibre. The things you learn!
2. Proxima is also a UV Ceti flare type variable star, so don’t pin your SETI hopes on finding any alien civilisations living there.
I hope you enjoyed reading about our nearest neighbouring star.
That’s it. Thanks for reading.
|SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.|
|Field flattener; No filter; 2x Powermate|
|SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.|
|Camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).|
|Software: PHD2; SharpCap, Gimp, EQMOD with Carte du Ciel.|
|Observatory latitude: 34° South.|
See annotated image at Astrometry.net