Thursday, 22 December 2016

Stars in another galaxy

Have you ever wondered what the universe would be like in another galaxy? Well, the answer's quite simple: very similar to our own. Of course, every star's different and there are probably planets out there so weird that not even the wildest science-fiction writer could've invented them. But basically the universe's quite the same everywhere. Stars are what they are... big stars, small stars, hot ones and cold ones. Most will die quietly as planetary nebulae, others are so massive that they'll explode as supernovae. But all of them are born in huge hydrogen clouds. I've already shown you many examples of these star-forming regions, such as the famous Swan Nebula and I've even made a video about flying into the Orion Nebula

But let's go back to my previous sketch, the one about the Triangulum Galaxy (M33). On the bottom sketch I've added labels to highlight some of the star forming regions in that other galaxy which are already visible to ordinary amateur telescopes. Each of these bright knots in the galaxy's spiral arms is a nebula complex, similar to the Orion, Swan and other star-forming nebulae. Inside those knots, baby stars are born. 

By far the biggest of these nebulae in the Triangulum Galaxy is the one on the far left, which astronomers refer to as NGC604. Can you believe that this nebula's so big that it's 1.500 lightyears in diameter? That's the distance from the Orion Nebula to Earth! This makes it probably the biggest nebula complex in our entire local group of galaxies! Encouraged by the spectacle I observed at low magnification, I pushed the binoscope to 507x and pointed it at NGC604. What I saw nearly made me tumble on the ground (and I was standing 6 steps up on a ladder). Not only did I see some incredible detail in that nebula (the slant "H" or "M" really stood out), I was able to see individual stars in it! They were impossible to pinpoint exactly - they were so tiny and they seemed to be "dancing" across the nebula - so on my sketch I just put some random dots to give you the idea. But I did see them!

I had always assumed that it was impossible to see individual stars in other galaxies with an amateur telescope because they're simply too far away. The Triangulum Galaxy lies at a distance of 2,8 million lightyears! But I was wrong. It is possible with a sufficiently big telescope and good sky conditions. 

These dots are bright and hot baby stars, much like the trapezium stars in the Orion Nebula. One day planets will form from the debris around them (if that hasn't already happened) and they'll start their journey through their galaxy like our little Sun's flying around our Milky Way's centre. So you see... the universe's pretty much the same everywhere.

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