Tuesday, June 9, 2015

Clusters and Molecules

Another week, another peek!

It's really hard not to give in to temptation and divert to that seemingly unique jewel you have spotted on your Galaxy Map. I did it a couple of times, going here, going there. Most of the time, it left me baffled about the beauty of the 'out here'. I remembered some of my Astrophysics lessons back at Tau Ceti and I realised that all these space phenomena are connected in a way. So even that far and remote place is just a puzzle piece of some greater thing. 
In my case, it's the so-called Carina Molecular Cloud (CMC) and it's known to be one of the biggest structures in the known galaxy, spanning hundreds of Lightyears in diameter. Although the Carina Nebula is still some 2,500 Light Years out, I am already moving through its associated complex, full of Open Star Clusters, younger regions of star formation (like the Carina OB1 and OB2 associations) and also some silent witnesses of stellar extinction, like the occasional Neutron Star or White Dwarf.

Speaking about Open Star Clusters, it is generally assumed that they all formed out of the CMC, although not all simultaneously. These clusters are generally some ten to fifty LY across and densely packed with stars, either in the form of a clump or more of a string. Some of their stars were so short-lived however, that they already ceased hydrogen fusion or even went supernova, explaining the occasional Neutron Star, Black Hole or even Wolf-Rayet star in those clusters. The Clusters' cores mainly consist of the more younger types of stars like O, B and also A types, and they can be easily spotted on the Galaxy Map by setting the star type filters accordingly. Here is an example of the larger Open Cluster of NGC 3590:

If ancient archives are to be believed, it took the 'Early Tech' astronomers of the 20th century quite some time to realise that most prominent nebulae are in fact only the 'hot spots' within the bigger Molecular Clouds. The Orion Nebula is a perfect example for this, and so is the Eta Carina Nebula. In ancient pre-spaceflight times, however, most nebulae were seen as separate entities. The bigger picture is, simply put, that Molecular Clouds are hard to detect, because they are cool and hence emitt barely any visible light. But when a star goes nova or supernova the ejected stellar material compresses the surrounding dark clouds, promoting star formation through gravitational collapse of the cloud. Young stars in turn emitt heavy energetic radiation that ionizes the interstellar medium and thus makes it 'shine' in different colours, depending on its chemical components. Ionized Hydrogen is most prominent, shedding the characteristic red light as can be seen in the region's magnificient Eta Carina and Statue of Liberty Nebulae (which can be seen below).

So for the non-poethic or non-aesthetic people, this beautiful nebula is just a relatively small patch of a Molecular Cloud made visible by some young stars' heavy radiation, much like an area of a green park lit by a lantern. The darker reaches remain obscure and, well, makes one itchy to redirect the Nav Computer and to go there and find out, what's there to be found. To honour this most endeavoring attitude, I have compiled a small collage of sights and places:

Now Eta Carinae is waiting. Time to get a close-up look at her beauty. Time to move on...

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