University of Minnesota | 2017 Jan 04
[img3="The left panel shows a false-color image of PGC 1000714. The right panel shows a B-I color index map that reveals both the outer ring (blue) and diffuse inner ring (light green). Credit: Ryan Beauchemin"]http://naturalsciences.org/calendar/wp- ... 40x480.jpg[/img3][hr][/hr]Approximately 359 million light-years away from Earth, there is a galaxy with an innocuous name (PGC 1000714) that doesn’t look quite like anything astronomers have observed before. New research provides a first description of a well-defined elliptical-like core surrounded by two circular rings — a galaxy that appears to belong to a class of rarely observed, Hoag-type galaxies. ...
Hoag-type galaxies are round cores surrounded by a circular ring, with nothing visibly connecting them. The majority of observed galaxies are disc-shaped like our own Milky Way. Galaxies with unusual appearances give astronomers unique insights into how galaxies are formed and change.
The researchers collected multi-waveband images of the galaxy, which is only easily observable in the Southern Hemisphere, using a large diameter telescope in the Chilean mountains. These images were used to determine the ages of the two main features of the galaxy, the outer ring and the central body.
While the researchers found a blue and young (0.13 billion years) outer ring, surrounding a red and older (5.5 billion years) central core, they were surprised to uncover evidence for second inner ring around the central body. To document this second ring, researchers took their images and subtracted out a model of the core. This allowed them to observe and measure the obscured, second inner ring structure. ...
A Photometric Study of the Peculiar and Potentially Double Ringed, Nonbarred Galaxy: PGC 1000714 - Burcin Mutlu Pakdil et al
- Monthly Notices of the RAS 466(1):355 (2017 Apr 01) DOI: 10.1093/mnras/stw3107