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 Post subject: Metal-poor Clusters
PostPosted: Wed Feb 06, 2019 9:32 am 

Joined: Sat Jan 26, 2008 4:03 pm
Posts: 556
Location: Galloway, SW Scotland
What a good few weeks it's been for observing – many nights out!

I was wandering around the North Galactic Pole (or rather, the field of view of my telescope was) in the early hours this morning, looking at multitudes of galaxies, when I remembered M53 in Coma Berenices, which I hadn't looked at for a few years, for some reason. I'd forgotten how small it appeared, requiring 400x in the 14 inch Dob for decent resolution. I also observed NGC5053 nearby, even smaller, rather less dense and very faint.

I noticed in my star chart that I'd penned in the fact that M53 was 60,000 LY distant, one of the more far flung clusters (though not nearly as far flung as another I've looked at, NGC7006 in Delphinus, at 135,000 LY, remote in the galactic halo); no wonder it appeared small!

Reading about the two clusters afterwards, I saw with interest, that they are classed as `metal-poor'. Interesting, thought to be metal-poor because they formed in a low-mass satellite galaxy of the Milky Way, which was eventually gravitationally sucked into our galaxy to remain near its outskirts. Had these clusters formed within the Milky Way they would have been much richer in heavier elements like metals, like the not-so-far-away-in-the-sky cluster M3. This theory of formation is supported by the fact that NGC7006 in Delphinus also has a very eccentric orbit.

What a fascinating hobby this is...awe inspiring!

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