2015년 2월 2일 월요일

[New post] Astronomy Photo of the Day: 2/2/15 — Arp 230

New post on From Quarks to Quasars

Astronomy Photo of the Day: 2/2/15 — Arp 230

by Jaime Trosper
Image Credit: ESA/Hubble & NASA, Acknowledgement: Flickr user Det58
Image Credit: ESA/Hubble & NASA (Acknowledgement: Flickr User, Det58)
This image shows the beautiful mess that is Arp 230 (otherwise known as IC 51), apeculiar galaxy pictured by the Hubble Space Telescope. 'Peculiar' isn't merely a word used to describe an object of this type, it's an actual category; one that was first conceptualized by Halton Arp in the 1960's.
Normally, peculiar galaxies become peculiar following a gravitational disturbance of some kind, like, say, a galaxy merger. This was almost certainly the case for Arp 230. In fact, astronomers assert that this very event resulted in the formation of its beautiful polar ring structure.
The ring itself is multi-layered. The outermost portion contains significant quantities of gas and dust, which rotate over the galactic poles of Arp 230. Astronomers believe that the smaller galaxy that was absorbed by the primary galaxy was perpendicular to the other one prior to the encounter. After which, the smaller one was torn to shreds, eventually birthing the ring.
What's more is that they also believe both progenitors galaxies were rather small, perhaps smaller than the Milky Way even. As time goes on, this version will likely take on a more traditional shape, mimicking the intermediate galaxies (those that lie between spiral and elliptical galaxies) we know and love.
Currently, the galaxy can be found about 60 million light-years from Earth in the Cetus constellation
See a larger image here.





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