Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Thoughts On Albireo

  • Please log in to reply
6 replies to this topic

#1 Frisky

Frisky

    Ranger 4

  • -----
  • topic starter
  • Posts: 316
  • Joined: 08 Feb 2019
  • Loc: Austin, Minnesota

Posted 16 August 2019 - 03:50 AM

All spring and summer, during outreach, I've explained to people that Albireo is an optical double and not a binary star system. Tonight, I googled it and found references that it is a binary system! Well, it's not. It's a likely optical double. Component B is a binary! This Sky & Telescope article is a good one on the subject:

 

https://www.skyandte...lease-stand-up/

 

Joe


  • Jon Isaacs, Bonco2 and happylimpet like this

#2 MikeTahtib

MikeTahtib

    Viking 1

  • -----
  • Posts: 810
  • Joined: 10 Oct 2016

Posted 16 August 2019 - 05:48 AM

I like the article's suggestion to look at WZ Cassiopeia instead if you don't want to explain the difference between optical and true doubles.  I stumbled onto it by accident when the carbon star must have been near minimum, because it was a deep LED red.  The sight was truly stunning.  I didn't realize it was a double, but I did notice there was a bright blue star nearby.   Under these circumstances, the color difference is more striking than Albireo's.  While not as easy to find as Albireo, it is not difficult with a Telrad.  Put the right-most (western-most) star of the W about 2/3 of the way between the outer and middle Telrad rings, and put the inner Telrad ring tangent to the line formed by projecting the western end of the W past the end star, and it should be in your filed of view.


  • payner and zleonis like this

#3 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 6309
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 16 August 2019 - 06:00 AM

I think Wiki is taking the safe route and saying it might or might not be a binary system.

Beta Cygni is about 415 light-years (127 pc) away from the Sun. When viewed with the naked eye, Albireo appears to be a single star. However, in a telescope it resolves into a double star consisting of β Cygni A (amber, apparent magnitude 3.1), and β Cygni B (blue-green, apparent magnitude 5.1).[32] Separated by 35 seconds of arc,[16] the two components provide one of the best contrasting double stars in the sky due to their different colors.

It is not known whether the two components β Cygni A and B are orbiting around each other in a physical binary system, or if they are merely an optical double. If they are a physical binary, their orbital period is probably at least 100,000 years.[32] Some experts, however, support the optical double argument, based on observations that suggest different proper motions for the components, which implies that they are unrelated.[33] The primary and secondary also have different measured distances from the Hipparcos mission – 434 ± 20 light-years (133 ± 6 pc) for the primary and 401 ± 13 light-years (123 ± 4 pc) for the secondary.[9] More recently the Gaia mission has measured distances of about 330–390 light years (100–120 parsecs) for both components, but noise in the astrometric measurements for the stars means that data from Gaia's second data release is not yet sufficient to determine whether the stars are physically associated.[34]

There are a further 10 faint companions listed in the Washington Double Star catalogue, all fainter than magnitude 10. Only one is closer to the primary than Albireo B, with the others up to 142" away.[11]

Since the Gaia data is unable to determine the status I would say that whatever we do is speculation. And people speculate towards the one they like.



#4 zleonis

zleonis

    Mariner 2

  • *****
  • Posts: 228
  • Joined: 27 Mar 2018
  • Loc: Richmond, VA

Posted 16 August 2019 - 09:17 AM

I like the article's suggestion to look at WZ Cassiopeia instead if you don't want to explain the difference between optical and true doubles.  I stumbled onto it by accident when the carbon star must have been near minimum, because it was a deep LED red.  The sight was truly stunning.  I didn't realize it was a double, but I did notice there was a bright blue star nearby.   Under these circumstances, the color difference is more striking than Albireo's.  While not as easy to find as Albireo, it is not difficult with a Telrad.  Put the right-most (western-most) star of the W about 2/3 of the way between the outer and middle Telrad rings, and put the inner Telrad ring tangent to the line formed by projecting the western end of the W past the end star, and it should be in your filed of view.

I also came across WZ Cassiopeiae by chance and I agree that this is one of the most striking pairs I've seen. WZ is doing most of the work in the color contrast, though, since I was surprised to see that the color index of the companion classifies it as a white star (its faintness and contrast with WZ Cas gives the impression of bright blue). Wikipedia suggests that this another merely optical pairing, but that's based on a study of their radial velocities from the 1950s. But I really enjoy this pairing - it stands out even in a fascinating part of the sky. 



#5 Frisky

Frisky

    Ranger 4

  • -----
  • topic starter
  • Posts: 316
  • Joined: 08 Feb 2019
  • Loc: Austin, Minnesota

Posted 16 August 2019 - 12:36 PM

I observe WZ Cas nightly. Eta Cas too. 

 

Joe


  • MikeTahtib likes this

#6 MikeTahtib

MikeTahtib

    Viking 1

  • -----
  • Posts: 810
  • Joined: 10 Oct 2016

Posted 16 August 2019 - 01:37 PM

I observe WZ Cas nightly. Eta Cas too. 

 

Joe

How dramatically does the color of WZ Cas change over its cycle?  I haven't been a regular observer, but I remember how deeply red it appeared the first time I saw it, but it hasn't quite lived up to that memory on a couple subsequent observations.  I'm wondering if my memory is over-stating what I saw the first time, or if I happened to catch it just right the first time and haven't gotten the timing right since.


  • Frisky likes this

#7 Frisky

Frisky

    Ranger 4

  • -----
  • topic starter
  • Posts: 316
  • Joined: 08 Feb 2019
  • Loc: Austin, Minnesota

Posted 16 August 2019 - 01:54 PM

To be honest, I've mainly observed subtle changes I attribute to sky conditions and the eyepiece I'm using. I always try different eyepieces on it to try to bring out more color. I've only observed it at Bortle 6. I'm going to be checking it in darker skies within a week and will report. To me, the carbon usually looks a deep copper color and the companion a pale blue. On a few nights, the carbon has been more of a deep red and the companion a sapphire blue! Really neat! However, the usual is copper and light blue for me.

 

Joe


  • JMKarian and zleonis like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics