Rho Ophiuchi Cloud Complex

[RobertM]

This is probably the most colourful part of the whole sky and is my second image with the little Askar SQA55 from Isla Palma. 



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A crop of M4 Globular cluster from the image with a bit less stretch:




There's obviously a lot going on in this colourful part of the sky:

This area of the sky is mostly in the constellation of Scorpious however the top right quadrant is in the constellation of Ophiuchus.  The whole complex is one of the closest star forming regions to us.

1. To the top left quadrant is Antares and the associated orange nebula complex it illuminates.  The star is a red giant of about 15 solar masses and is actually one of the largest stars visible to the naked eye, it's diameter puts its surface out at about the asteroid belt (if centred on the sun)!
2. The right middle quadrant contains the blue subgiant star Rho Ophiuchi (brighter of the three) and the blue nebula lit up by it's emissions.
3. Imbedded in the Antares nebula is the blue reflection nebula IC4605 illuminated by the hot blue star 22 Scorpii.
4. To the bottom left of middle is the multiple star system Sigma Scorpii surrounded by both emission and reflection nebula ionised by the star.  Also called the Sigma Scorpii nebula the official designation is Sh2-9.
5. Just right of centre is the reflection nebula IC4603 which is primarily illuminated by the intense UV radiation of the hot young star HD147889.  There is also a slightly reddish tint caused  excited Ha emissions.
6. In the lower left is the M4 Globular cluster.  This cluster is about 75 light years across and 6,000 light years away making it visually the same size as the full moon.  It is also notable as the first globular cluster where individual stars were resolved.  You can also see the faint dust lane present in most globulars.
7. In the lower right hand corner is M80, which is 20% larger than M4 but also over five times further away, it is also one of the densest of the Milky Way globulars.  A lot of the stars in the cluster are metal deficient indicating very old stars (perhaps 10 billion years or more).

Capture details:
Location: Puntagorda, Islas La Palma
Telescope: ASKAR SQA55
Camera: ASI2600MC Duo
Filter: Player One UV/IR cut
Mount: ZWO AM3
Capture hardware ASIAir Plus
SubExposures: 19 x 300s

[Carole]

Lovely Robert, one of my favourite targets.  However unlike you, it took me 2 trips to Spain and 2 trips to DSC to get anything decent, spread over 6 years. 

A nice lot of information there, I will attempt to summarise at Members images. 

I remember your previous Rho Ophiuchi Cloud Complex from a fair few years ago, this is a step up from that one. 
I am always fascinated by the bit that joins the Antares Nebula to the Rho Ophiuchi nebula with that "pinched" appearance.  It took me some years to realise that is in fact dark nebulosity causing that pinched look.  I can see it quite well on your image. 

Carole

[Dave A]

Lovely image Robert
The colours are great