From Blob to Collisional Ring
This week’s OOTW features this object (below) from Tsering’s OotD posted on the 26th of June.
As Tsering showed, this seemingly uninteresting blob on the SDSS turns into this in Hubble Zoo:
This is AHZ30000yv, a wonderful collisional ring galaxy! I love seeing the huge differences between the SDSS and Hubble images, the reason why Hubble can see more is because it’s out of the way of the Earth’s atmosphere, so even though Hubble is actually smaller than the the Sloan telescope (Hubble’s mirror is 2.4 meters and the Sloan telescope’s mirror is 2.5) it can see further, taking us visually back to when the universe was around half its current age and making me very happy indeed!
This ring galaxy has a Z (redshift) of 1.432, so we’re seeing it as it was 9.15 billion years ago, just under 5 billion years after the big bang! So how did this galaxy end up as a collisional ring? The ring formed after another smaller galaxy punched through the centre of the galaxy, creating masses of hot young blue stars in the process through all the gravitational disruption.
And I have to quote this lovely post by Budgieye from the comments on Tsering’s OotD 😀 :
It is fun looking at the difference.
There must be lots of UV light coming from it, otherwise nothing would be visible at all on SDSS. At that distance, the ordinary blue light from the stars would be redshifted off the limits of the SDSS detector for far red light.
A nice addition to
Colours of Galaxies in SDSS : Redshift chart