Σάββατο, 4 Ιανουαρίου 2014

Μια κοσμική… τηγανίτα. Flat as a pancake

This newly released Hubble image shows spiral galaxy ESO 373-8, which is located roughly 25 million light-years away. Located some 25 million light-years away, this new Hubble image shows spiral galaxy ESO 373-8. Together with at least seven of its galactic neighbors, this galaxy is a member of the NGC 2997 group. We see it side-on as a thin, glittering streak across the sky, with all its contents neatly aligned in the same plane. We see so many galaxies like this — flat, stretched-out pancakes — that our brains barely process their shape. But let us stop and ask: Why are galaxies stretched out and aligned like this? Try spinning around in your chair with your legs and arms out. Slowly pull your legs and arms inwards, and tuck them in against your body. Notice anything? You should have started spinning faster. This effect is due to conservation of angular momentum, and it’s true for galaxies, too. This galaxy began life as a humungous ball of slowly rotating gas. Collapsing in upon itself, it spun faster and faster until, like pizza dough spinning and stretching in the air, a disc started to form. Anything that bobbed up and down through this disc was pulled back in line with this motion, creating a streamlined shape. Angular momentum is always conserved — from a spinning galactic disc 25 million light-years away from us, to any astronomer, or astronomer-wannabe, spinning in his office chair. Image: ESA/Hubble & NASA

Μια ακόμη εντυπωσιακή εικόνα από το Σύμπαν προσέθεσε στον μακρύ του κατάλογο το διαστημικό τηλεσκόπιο Hubble. Το τηλεσκόπιο φωτογράφισε τον γαλαξία ESO 373-8 που βρίσκεται σε απόσταση περίπου 25 εκατομμυρίων ετών φωτός από εμάς. Ο ESO 373-8 ανήκει στο γαλαξιακό σμήνος NGC 2997 και εξαιτίας του σχήματος του έχει λάβει τον χαρακτηρισμό «τηγανίτα» από τους ειδικούς. Δεν είναι ο μόνος γαλαξίας… τηγανίτα στο Σύμπαν αφού διάφορα φαινόμενα και κυρίως η στροφορμή «υποχρεώνουν» ορισμένους γαλαξίες που ξεκινούν ως γιγάντιες μπάλες περιστρεφόμενων αερίων να μετατρέπονται σε λεπτούς κοσμικούς δίσκους.