ngc660

NGC 660

Astronomers classify NGC 660 as a polar ring galaxy. It lies approximately 20 million light-years away in the constellation Pisces the Fish. A polar ring galaxy is a type in which an outer ring of gas and stars rotates over the poles. A rare galaxy, they have a substantial population of stars, gas, and dust orbiting in rings perpendicular to the plane of the galactic disk. This distortion may have resulted when NGC 660 captured material from a passing galaxy. (17-inch Planewave CDK17 Corrected Dall-Kirkham Astrograph at f/6.8, Apogee Instruments U16 CCD camera, LRGB image with exposures of 6.6, 2, 2, and 3.6 hours, respectively)

Contributed by Bill Snyder from Connellsville, Pennsylvania

Explanation: NGC 660 is featured in this cosmic snapshot, a sharp composite of broad and narrow band filter image data from the Gemini North telescope on Mauna Kea. Over 20 million light-years away and swimming within the boundaries of the constellation Pisces, NGC 660’s peculiar appearance marks it as a polar ring galaxy. A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dust orbiting in rings nearly perpendicular to the plane of the galactic disk. The bizarre-looking configuration could have been caused by the chance capture of material from a passing galaxy by a disk galaxy, with the captured debris eventually strung out in a rotating ring. The violent gravitational interaction would account for the myriad pinkish star forming regions scattered along NGC 660’s ring.The polar ring component can also be used to explore the shape of the galaxy’s otherwise unseen dark matter halo by calculating the dark matter’s gravitational influence on the rotation of the ring and disk. Broader than the disk, NGC 660’s ring spans over 50,000 light-years.

arxiv.org
[1507.01781] A new period of activity in the core of NGC660

[ Authors ]
Megan Argo, Ilse van Bemmel, Sam Connolly, Robert Beswick
[ Abstract ]
The core of the nearby galaxy NGC660 has recently undergone a spectacular radio outburst; using a combination of archival radio and Chandra X-ray data, together with new observations, the nature of this event is investigated. Radio observations made using e-MERLIN in mid-2013 show a new compact and extremely bright continuum source at the centre of the galaxy. High angular resolution observations carried out with the European VLBI Network show an obvious jet-like feature to the north east and evidence of a weak extension to the west, possibly a counter-jet. We also examine high angular resolution HI spectra of these new sources, and the radio spectral energy distribution using the new wide-band capabilities of e-MERLIN. We compare the properties of the new object with possible explanations, concluding that we are seeing a period of new AGN activity in the core of this polar ring galaxy.