Sunday, 22 April 2018

M63: a spring sunflower

Sunflowers are usually a thing of summer, but there's a very peculiar one that blooms in spring already. Point your telescope, or even your binoculars, under the big dipper's handle and you'll easily find this spectacular galaxy. Number 63 on Messier's list looks very much like a sunflower indeed, with it's bright, yellow core and flocculent spiral arms. Unlike "grand design" spiral galaxies, the spiral arms of M63 appear patchy, like a heap of cotton balls. It was also one of the first galaxies in which a spiral structure was recognised, by Lord Rosse, halfway the 19th century. 

The Sunflower Galaxy lies approximately 37 million light-years away from us and is a part of the M51 galaxy cluster, along with a few smaller ones. 

Physically, the Sunflower is a very active galaxy and every knot is an area of intense star formation. More interestingly, photographs revealed a wide halo around it which materialised most likely after an encounter with a dwarf galaxy, somewhere within the last 5 billion years. From the specific properties of the stars in this halo, scientists believe that this dwarf galaxy might have originated in our own local galaxy group.

Now as for the cherry on the cake: look slightly to the left of our Sunflower and you may spot a tiny smudge. No, it's not an extended part of M63, nor is it an accompanying dwarf galaxy. It's proper motion, a breathtaking 23,500km/sec away from us or almost 8% of light speed, is far too great for it to be anywhere near M63, or within the boundaries of our area of the known Universe. It's a giant galaxy, denominated PGC4018103, three times the diameter of our Milky Way, that lies 1.2 BILLION light-years away from us. As such, it's probably the most distant object I've observed so far. Just imagine... The few photons of this galaxy that I managed to capture with my eyes, left their origin when the first multicellular life-forms emerged in the Precambrian seas.

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