RS Cygni – a Carbon star lying close to the Crescent nebula in Cygnus

RS Cygni

Star name:                                           RS Cygni

Other names:

Constellation:                                      Cygnus

Other ID:                                             SAO 69636, HIP 99653, PPM 84477, HD 192443, B+38 3957

Magnitude:                                          7.1 to 8.5

Absolute magnitude:                            -0.77
+/- 0.92

Luminosity, Sun = 1:                           170 +/- 140

R.A. 2000:                                          20hr 13min 23.662sec

Dec 2000:                                           38deg 43min 44.47sec

Spectral type:                                      C5II


Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       1550 +/- 650


This Carbon star lies very close to the Crescent nebula (NGC6888, an emission nebula formed from the Wolf-Rayet star HD 192163) in the constellation Cygnus.  The mean period of the variability of RS Cygni is 434.1 days.

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2 Responses to RS Cygni – a Carbon star lying close to the Crescent nebula in Cygnus

  1. James says:

    I’m a very new astrophotographer and took the time this weekend (Aug 13th 2017) to try and image NGC6888 with my 8inch reflector.
    Despite a bright moon and annoying random clouds, I managed 13 two minute exposures of the crescent nebular and surrounding area with a Canon 1100D and Explore Scientific UHC filter.
    Whilst viewing the live images on the camera I was quite surprised to find a remarkably bright red spot above the nebular. I initially thought the spot was a “hot pixle” but noticed that it was in every frame and looked just like a star!
    When I eventually processed the images I found to my surprise that it is indeed a star, RS Cygni to be exact.
    Unfortunately, I’ve never herd of ‘carbon stars’ so I never actually looked through the scope to view it, but now I know it’s there my next observing session with address that!

  2. Greg Parker says:

    Carbon Stars – Rubies of the night sky 🙂

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