Rho Ophiuchi Nebula Complex

Nothing was working right with this shot, first up. Went to process it my normal way and it was turning out like a dog's breakfast. So, I switched over to APP and everything went smoothly!!! So, here we are, the Rho Ophiuchi-Antares region at the head of Scorpius, in the luminance channel only. I had to cut my run short last night as I was running out of time (moon was coming up) and I'd started late as it was. But, I like the B&W pics. You see more of the structure of your object and aren't distracted by such superfluous things like colour :) I will be adding the colour to this at a later stage, so I'll have two versions...colour and B&W.

Anyway, there are three globular cluster in this image, M4 (the large cluster near the bottom right), ngc6144 (at the 2 O'clock of Antares) and M80 at the upper right. M4 is a large (75ly across) nearby (7.2Kly-2.2Kpc) globular cluster that is around 12.2Ga in age. It's mass is around 6.7x10^4 solar masses and it's one of the closest globular clusters to our home. The cluster contains some 43 variable stars and at least 2 millisecond pulsars, both which appear to be in binary systems with other neutron stars. Its white dwarf stars are amongst the oldest in the galaxy, with one remarkable white dwarf that is part of a binary system with the pulsar PSR B1620-26 and is also orbited by a planet 2.5 times Jupiter's mass. M80 is another globular cluster that can be seen in the area, but it is considerably further away than M4, at 36200ly (10Kpc). It is also somewhat larger (96ly across, 5.04x10^5 solar masses) and older, at 12.54Ga. M80 is notable for harbouring a great number of blue straggler stars, or stars that appear to be younger and hotter than they'd otherwise would be. Many of them appear to concentrated towards the core of the cluster and it's believed that the cluster has a high capture and collision rate. NGC6144, is a sparse looking globular cluster, compared to either M4 or M80, and is around 14.5ly in diameter at its distance of 8.5Kpc (27.7Kly). It is also considerably less massive than the other two clusters.

Several prominent stars also appear in this image. Antares (aSco) is a class M2Iab supergiant that lies approximately 600ly from Earth and is one of the most prominent members of the Scorpius-Centaurus OB1 Association of stars. Some 12-15 times more massive than the Sun and 700 times its linear diameter, the star would easily fill the solar system out to the inner Asteroid Belt. It's nearing the end of its life and will most likely explode as a Type II supernova in a few million years. Antares is a binary star, it's much smaller companion appears to be a blue (B) main sequence star, which appears by eye to be a blue-green colour when compared to the ruddy Antares itself. Antares is surrounded by a rare orange-yellow reflection nebular which reflects light in the longer wavelength of yellow to orange-red light due to the large size of the particles which make it up (550-700nm)

Al Niyat (tau Scorpii, in this case) is a B0V class star which lies some 430ly from Earth, Part of the Upper Scorpius Association, the star radiates at around 18000 solar luminosities and weighs in at about 12 solar masses. It appears to be a very slow rotator (5kms), which is highly unusual for a B class star, but this is likely due to its rotational axis pointing directly at us, so we don't actually see it's true rotational velocity. From its surface temp of about 30700K, we can deduce it's radius to be around 5 solar, which for an upper B class star is on the large side.

Omicron Scorpii (oSco), is one of a rare class of stars, bright A class giants, with its spectral class being A4II-III. Some 15 times the size of the Sun and 8 times its mass, the star shine at around 3162 solar luminosities and has a surface temp of around 8128K. It rotates on its axis at 23km-s and is some 900ly (270pc) away from Earth. Once thought to be part of the Upper Scorpius Association, it is now believed to be a background star. It's radial velocity is around -8.2km-s, meaning the star is approaching us at around that velocity. The star is also approximately 39.8Ma in age, which would make it somewhat older than the average star of the Upper Scorpius Association and of the Sco-Cen OB1 complex as a whole.

The main star of the rho Ophiuchi Cloud Complex, rho Ophiuchi, is a multiple star system consisting of at least 4 B class main sequence stars- subgiants. The main system, AB, consists of 2 B2V-IV stars in orbit about one another at an apparent separation at their distance (460ly) of around 344AU, with a period of around 2400 years. Star C lies some 17000AU from the primaries and DE, around 19000AU. C and DE are all B type main sequence stars. DE is a binary star with an orbital period of around 680 years.

The rho Ophiuchi Cloud Complex lies at around 460ly (131pc) from Earth and is one of the closest star forming regions in the Galaxy to our planet. Weighing in at a round 3000 solar masses, the cloud complex consists of two major regions of dust and gas (L1688-Upper and L1689-Lower) and their filaments of dust and gas which radiate out from these centres (L1709-L1755 and L1712-1729, respectively). The clouds range in temp of around 13-22K and the L1688 cloud contains around 425 discrete infrared sources, many of them pre-main sequence stars and protostars. 16 protostars, 123 T-Tauri with thick circumstellar disks and 77 weaker T-Tauri type pre-main sequence stars with thinner disks, have been found in L1688, with the last two categories of stars being 100Ka-1Ma years in age. A brown dwarf has also been found in the L1688 cloud complex and no doubt there are many more present there which haven't yet been found.

Pic was taken with T8 (iTelescope, SSO) 10x3min subs.
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