Alpha Centauri

Our Nearest Star System

There’s something about Alpha Centauri that intrigues people. At public nights, I sometimes get asked if I can show it, especially by visitors from the Northern Hemisphere. Maybe it crops up in science fiction movies, I wouldn’t know, as movies don’t interest me much.

Designation:       Alpha Centauri, Rigil Kentaurus, V645 Centauri.
Constellation:Centaurus.
Magnitude: +1.35 (Alpha Centauri A). +0.01 (Alpha Centauri B).
Spectral class:G (Alpha Centauri A). K (Alpha Centauri B).
Separation:5.9″.
Distance:4.37 light years.
Image date:2020-08-25.
Exposure:10 x 30 sec.
Field of View:47.8 x 31.7 arcmin; up is 175° E of N.

Alpha Centauri is a triple star system, deep in the Southern sky. Its three stars are labelled A, B and C and they are the three closest stars to the Sun.

I recently posted an image of Alpha Centauri C, otherwise known as Proxima Centauri, which is a rather dim star well outside the above image that took time for me to identify. It’s distance from us is 4.244 light years

No such trouble with the two very bright Alpha Centauri AB stars. They form a close binary system, with two stars that are too close to separate. The brightest is Alpha Centauri A, which is a Sun-like star. Alpha Centauri B is slightly dimmer but they seem merged in their joint glare. Both stars are located 4.37 light years away.

Do not confuse Alpha Centauri B with Beta Centauri (Hadar), which is an unrelated bright star, about 2° away, outside the above picture.

Alpha Centauri and Beta Centauri form the two bright “Pointers” which lead to the Southern Cross. The wide angle image below shows the two Pointer stars and the Southern Cross. (It also includes Proxima but it’s just one of the multitude of dim stars in the Milky Way star cloud).

Alpha Centauri AB, Beta Centauri (The Pointers) & Crux (The Southern Cross),
90s total, 50mm, f1.4 to f/4 ISO 2000-2500
(RP 2016-04-02)

The ultimate future for the Alpha Centauri system is apparently bleak. First, Alpha Centauri A will become a red giant, shedding much of its mass, which will release Proxima from the system.

Then, Alpha Centauri B will go through the same process and both of them will evolve into white dwarf stars. My understanding is that they, too, will also disassociate – leaving all three component stars to live an independent existence in their declining last few trillion years. 😢


The Seven Best Southern Sky Objects

Telescope Details
SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener; L-Booster UHC-S light pollution filter; 2458276; 2x Powermate
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: EQMOD, Cartes du Ciel, PHD2, SharpCap, Gimp.
Observatory location: 34° South.

See annotated image at Astrometry.net

19 Comments

  1. So, are you telling me that my fate is in the stars?? I always thought so.
    My grandson who had Muscular Dystrophy; died in 2012 He and I would look at the stars together. Then a small planetarium had a fundraiser and so I had a star in Alpha Centauri named for him A small form of immortality for him that appealed to my scientific and mythic interests.
    Again thank you for posting your super photos.
    Fran

    Liked by 2 people

    1. That’s very sad indeed, Fran. To lose a grandson must have been unbearably confronting. Thank you for sharing it with me. I hope you still get to look at the stars with someone whenever you get the opportunity.

      I really miss my observing sessions with my friends, it was always so inspiring to sit in the open air away from the city and gaze in wonder at the Universe above us, discussing what we see. I’m just making do with the suburban skies alone at home this year.

      Very best wishes.
      Roger

      Like

  2. I must admit to never having looked up the location of Alpha Centauri. Perhaps the fact it is never visible from 42˚ north is one reason. I do recall it being mentioned a lot in TV and movies. Thanks for giving me a good sense of where it is.

    Like

  3. When I look at the Moon, I think of the men that landed there, all the probes we have sent, and let my imagination run wild about the possibility of traveling there, because it’s so close. I think Alpha Centauri conjures up the same intrigue, but on a scale for the entire galaxy.

    Being the closest star/system to our Solar System, I can understand the interest to view it, to look upon what hopefully is someday our first destination in interstellar travel.

    Like

    1. Yes, Alpha Centauri is special for exactly that reason. I sometimes get asked about it at public nights, so I thought a photograph might be of some interest.

      It’s ok to dream but I’m not convinced the average person has any real concept of the astonishing extra-solar distances, even to Alpha Centauri.

      😨

      Liked by 2 people

        1. Thanks for that perspective. 😵

          The distances between stars are so humongous, I do not foresee humans ever leaving the Solar System. The fasted craft we’ve built have travelled four decades and are still in the Solar System (depending on how you define Solar System) but we can all still build our own spaceships of the imagination – just like Carl Sagan did – and travel to the stars and explore the worlds we hope are out there.

          I wonder they will have covid on other planets….

          🚀

          Liked by 1 person

        2. Don’t you know!?! Aliens brought COVID in their UFOs!!!

          . . . I thought everyone knew that . . .

          Seriously, I agree with you; while we should never say never, short of a complete revolution in physics and the upending of everything we’ve learned, we’ll be lucky if we even come close to leaving the Solar System . . . mostly because we’re not focused on the long view and because we are — by all evidence — on a path to self-destruction.

          And, on that cheerful thought, yes, we can imagine lots more than we can achieve.

          Liked by 1 person

          1. Dreaming we’re going to the stars is ok with me, even though it is unlikely. I want to go there. I want to see the Universe…

            Dreaming that we are not already on the inevitable path to self-destruction is what bothers me. It brings me down to Earth.

            Liked by 1 person

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