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Memories - report of 09-24
After 3 years of equatorial night sky, in wich I could see the Pole star (Alpha UMi) together with the Southern Cross, I came back to my island, Sardinia. This is not a bad place for stargazers, in Sardinia there are few inhabitants and the night is often deeply dark. Just using a simple 10x50 binocular, I restart to watch my sardinian sky, orphan of the southern Milky Way and magellanic clouds...
The Big Dipper turns around my shoulders when I look south, near the galactic centre. Scorpius starts to set down, when I look the brilliant complex of NGC 6231: this is a fairly important structure of the Sagittarius Arm of our galaxy, a place in wich star formation takes place generating high-mass stars, the Scorpius OB1 association.
But tonight I'm not interested on objects belonging to the inner arms; I'm looking for our arm, the Orion Spur, and its objects. Furthermore, I want to do that in a very simple manner, without my telescope, only using a binocular; I want to enjoy the sky as I did when I was at the beginning of my passion.
From our perspective, Orion Spur is thought to start near Sagitta, or in the northernmost part of Aquila, near W51 nebulous complex, detaching from the Sagittarius Arm. This complex is obviously out of sight for my binocular, so I try to capture the farthest object of our spur that I can see, NGC 6820, a very small open cluster, a small bright patch 4°W to the Dumbell (M27); this object is part of Vulpecula OB1, an OB association at 2300 pc (7500 ly).
Cygnus region is the most prominent feature of Orion Spur, here we can see our arm along its median line. M29, the small M29, is a good signpost, so close to Cygnus X molecular cloud (at 1500 pc - 5000 ly), one of the most important star forming regions of all Local Group of galaxies. Unfortunately, this region is obscured by the dark patch of the Cygnus Rift, a sort of coalsack, part of wich is illuminated, becoming the North America Nebula, at 600 pc (1960 ly). Cepheus and Cassiopeia are arising at NNE, bringing with them a window to the outer Perseus Arm, in wich nice and fairly brilliant clusters like M52, M103, NGC 457 and NGC 663 lie. M52 is a small nebulous patch through my binocular, as well as M103.
The Pole star is like a nail, a new sky arises at east, first is the Double Cluster in Perseus, then Pleiades and Hyades, and the hourglass Orion, Sirius, all Canis Major. Achernar is really too south, ever below the horizon. The Double Cluster, in Perseus Arm, is an amazing object with binoculars; dozens of stars are clearly visible, and all the field around it is rich of the blue components of Perseus OB1 association. We, watchers from northern hemisphere, we use to dream, what a wonderful sky and wonderful objects are in southern heaven; and we often forget to fully enjoy our sky, our hidden treasures placed in the northern Milky Way.
When Puppis arises, the first light of the Sun means the beginning of a new day. I focus my attention to a curious and anonymous group of stars, the Pi Puppis cluster, AKA Collinder 135; it lies phisically near the edge of Gum Nebula, at 260 pc (840 ly), and it seems to share its origin with all the stars around it. The galactic region is the same of the Gamma Velorum cluster, Vela OB2, even if Vela OB2 is a bit younger than Collinder 135.
Clearskies to all
Ro84
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