As we quickly approach the middle of Winter, are also treated to both the best observing conditions of the year (when its not raining that is!) and a plethora of gorgeous sights up in the night sky. Having been introduced to Pearltrees by the lovely Miss Whitcroft, I’ll be using it in future posts to provide a simple way to know what you can see with a telescope or your naked eye in various constellations that I mention!
So what are we treated to at the moment? Well both the constellations of Scorpius (apologies for the Northern Hemisphere constellation names, this is really the Great Fish-Hook of Maui) and Sagittarius are easily visible in our evening skies at the moment, beginning the evening just over the eastern horizon and rising to be places almost directly overhead by about midnight. Finding Scorpius/Maui’s Fish Hook is simple – just look for the only bright red star high up in the eastern sky, this is Antares or Rehua, and forms either the ‘heart’ of Scorpius, or the drop of blood Maui used to bait his Fish-Hook respectively – either way it’s very distinctive! Near to Antares is a ‘crook’ of bright stars that make out the tail of Scorpius, curled around one of the widest segments of the Milky Way.
But, once again, other than being easy to find, the stars of Scorpius itself really aren’t particularly interesting (excepting supergiant, red, soon-to-supernova Antares), but because of it’s proximity to the galactic centre it houses several awesome stellar spectacles: Messier Objects 4,6,7,80 and NGC 6302, 6334, 6357 and 6388. Most of these are impressive open or globular clusters with tens to thousands of members, but the really impressive ones (well in my book – clusters are interesting but for less visual reasons!) are these 3 nebulae:
First up is the Butterfly Nebula, a complex and immense cloud of ionized gas. The central star, which was obscured by dust until a few years ago, is probably only about 60% of the mass of our sun (it’s a white dwarf), but in order to create the incredible colours apparent in this picture, must have a surface temperature of between 200,000 and 400,000 degrees Kelvin!
The huge lobes of gas (the butterfly’s ‘wings’) used to be part of the central star, but a catastrophic ejection event blew off the outer layers, creating the spectacle we see, but also a dense, dark, dust ring surrounding the nebula that may have also contributed to the formation of this shape. Second we have the Cat’s Paw Nebula, so named after the outline of a cosmic feline’s footprint outlining this nebula. This is one of the most active star-forming regions in our galaxy, and the red hydrogen gas conceals the large number of hot, young ( well…less than 100 million years old) blue stars nestled deep within it. Finally, we have NGC 6537. This diffuse nebula shows a cluster of stars, Pismis 24, at the top and a vast blanket of star-forming dust and gas at the bottom. Wrapped up within those peaks are proto-stars themselves, but the dust scatters their light making them difficult to sea and creating the illusion of a seething ocean of dust reaching out for the star cluster hanging delicately above it. Unfortunately, because of the use of False Colour images, none of these objects appear like this to us from the earth (unless you work at a particularly state of the art observatory) and the best we get to glimpse are tiny wisps of blue haze around the central star, tantalizingly hinting at the mysteries beneath! That said the other objects in Scorpius are much easier to see, hence my use of this Pearltree to help you find where they are and what the look like should you want to find them! And feel free to track the tree back and take a look at the other constellations (the Winter ones are almost complete, but the other seasons are still being finished in my spare *laughs* time)
1) Szyszka, C. et al “Detection of the Central Star of the Planetary Nebula NGC 6302” The Astrophysical Journal Letters, 707, L32-L36 (2009) doi:10.1088/0004-637X/707/1/L32