NGC 4651 - Arp 189

Object: NGC 4651 a galaxy in Coma Berenices also known as Arp 189 which is classified as a Galaxy with Narrow Filaments, 10.6m, 4' x 2.6', type SA(rs)c, distance 15.3 Mpc (50 Mly), diameter ~59 kly. This galaxy is also a LINER, for another example of this kind of galaxy and description see NGC 5953/5954.

Subimages: 13 x 600 sec at f/10, 14 x 600s at f/6 (4.5 hrs)
Scope: C11XLT efl=2940mm and with reducer-corrector efl=1588mm
Mount: Losmandy G11 with Gemini
Camera: ST8XME set to -30C and -25C
Guiding: Self-guide, ExpTime = 2 sec, dithered.
Acquisition and Processing: MaxIm DL/CCD v4.5 and CCDSharp
Imaged between: March 24 and May 13, 2007
Masters class winner of SCT-User 2007 Imaging Contest. Many thanks to organizer Rod Molisse and sponsor Astronomics Inc. who donated an Astrotech 66ED telescope with SCT rings. See this site for all the contest entries.

SD Mask combine of best frames to produce two masters (f/10 and f/6).
Placed 1530x1020 f/10 image into enlarged (3060x2040) canvas with bgd level adjusted.
Average combine of resized f/6 master with f/10 enlarged canvas.
Create flat field from multiple Erosion/Avg filters, divided by flat.
CCDSharp LR deconvolution 4 iterations
DDP, crop and cosmetic star repair.
Resized down by a factor of 2.
A full size version (2730x1760, 530kb) can be viewed here.

The area SE of the galaxy has been extensively studied due to the nearby radio loud quasar 3C275.1 (redshift z = 0.557). However the unusual optical jet terminating 75 kly from the nucleus with a diffuse perpendicular arc to the E of the galaxy has not been studied in great detail, and very few deep images of this feature exist. Evidence of further disruption is visible to the W of the galaxy in the low surface brightness envelope. Two faint dwarf galaxies have possibly interacted with the main system, one located 8' WSW and another 2' E. In the cropped/stretched raw master frame below I have labeled the quasar: Q, a distant galaxy gravitationally associated with it: G1 and the nearby dwarf galaxy: D. X-ray images of the area show a very strong flux from the quasar, the core of NGC 4651 and two lobes E and W of the core, the east lobe extending nearly to the dwarf galaxy, and the W lobe being on a line coincident with the jet. In order to overlay the x-ray data with my optical data I have blended in figure 7 from H. Arp's publication: X-ray observations of five galaxy-quasar associations, Astronomy and Astrophysics 316, 57-78 (1996). The original figure was rotated 1.5 degrees and resized to match the image scale and orientation of the CCD image. I quote the original figure caption for clarity: " Fig. 7. X-ray isophotes at 2, 3, 4, 8 and 10 sigma are shown around the quasar 3C275.1 and the optical jet galaxy NGC 4651. In the harder energy bands (0.7 to 2.0 keV) the quasar has an extension, or jet, to the east as well as the softer extension to the west visible here. The source near the end of the optical jet is conspicuous in harder bands and is estimated to be real."

The evidence put forward by H. Arp for interaction between the quasar and NGC 4651 has been put into question by M. J. Hardcastle in: Determining the reality of X-ray filaments, Astron. Astrophys. 357, 884-890 (2000). However regarding the east-west X-ray extensions he concludes that: "... the extension of NGC 4651 is likely to be real."

For more details see also:
Discovery Of Optical Emission In The Hot Spots Of Three 3CR Quasars: High-Energy Particle Acceleration In Powerful Radio Hot Spots, The Astrophysical Journal, 628, 104–112 (2005).
And an oblique reference to the jet is made in the following article:
The Nature of the Optical "Jets" in the Spiral Galaxy NGC 1907, The Astronomical Journal, 114, 115-121 (1997).

This galaxy was host to supernova SN2006my discovered on Nov 8, 2006 at ~13m a few months after it had exploded. It is classified as a type II-P with a low mass red supergiant progenitor (~10 solar masses). I estimate it is still glowing in my image at ~18.7m. For more details see: On the Progenitors of Two Type II-P Supernovae in the Virgo Cluster, Li, Weidong et al., The Astrophysical Journal, Volume 661, Issue 2, pp. 1013-1024.