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Object Details: This time of year in the Northern Hemisphere brings what many astrophotographers refer to as 'Spring Galaxy Season'. Having taken some shots of M65 & M66 at this time last year, as the first test images since re-opening the RoR observatory I built at my home here in upstate, NY after it's long winter slumber, I thought I'd try to complete the images required for the attached composite.
The Leo Triplet is a group of three gravitationally interacting galaxies consisting of NGC 3628 (left, aka 'The Hamburger Galaxy'), M65 (upper right) and M66 (lower right). All three galaxies are classified as spirals, and their structures are being disrupted as they gravitationally interact with each other. From Earth's perspective each is tilted at a different angle, with NGC 3628 oriented nearly 'edge-on' and thus showing a very prominent central dust lane bisecting the galaxy.
The group lies approximately 35 million light-years from Earth, and at that distance, the wide-field view shown at center covers approximately 2 million light-years in diameter, edge-to-edge. M65 has a diameter of approximately 90,000 light-years, M66 is slightly larger at 95,000 light-years while NGC 3628 is about 100,000 light-years in diameter (comparable to the diameter of our own Milky-Way).
Among other effects, their gravitational interaction results in the asymmetric spiral arms and off-center core of M66, caused by the combined pull of M65 & NGC 3628; as well as a 300,000 light-year long 'tidal stream' of stars trailing from NGC 3628, part of which is faintly visible to the lower left of the galaxy in the wide-field image. M65 & M66 each contain about 200 billion stars while NGC 3628 contains over 300 billion, with it's tidal stream alone consisting of approximately 500 million solar masses.
M65 & M66 lie about 160,000 light-years apart, which is comparable to the distance between our own Milky-Way and it's satellite galaxy The Large Magellanic Cloud. NGC 3682 lies over 300,000 light-years from the M65 / M66 pair and simulations of their movement though time suggest that NGC 3628 & M66 came within 80,000 light-years of each other 800 million years ago. The asymmetry of M66 & it's off-center core and the stellar tidal stream of NGC 3628 as well as other disruptions and asymmetries maybe be remnants of the result of this close encounter.
When I first noticed the 'mottled' appearance faintly visible though-out the wide-field image after stacking (most prominent on the lower right and the left sides), I thought it might be noise, yet it looked somewhat suspicious. When comparing it's relative location with very deep images of this region, it seems to align with the Integrated Flux Nebula (IFN) surrounding this area, which until then I did not know was even present in this region of the sky. For more detail regarding IFN, probably most often imaged around the M81 / M82 galaxy pair, please see the shot at the following link where it is much more prominent and thus 'easier' to image
(relatively speaking of course) - www.flickr.com/photos/homcavobservatory/48762740192/in/al...
Image Details: The attached images were taken Jay Edwards on March 21, 2020 and April 8th & 9th, 2021 and consist of a total of over four hours of integration time (in addition to the associated bias, flat & dark calibration frames).
Since I often shoot simultaneously using twin unmodded Canon 700D (t5i) DSLRs, the wide-field shot at center was imaged with an 80mm f/6 carbon-fiber triplet apochromatic refractor (i.e. an Orion ED80T CF) connected to a Televue 0.8X field flattener / focal reducer; while the individual shots of NGC 3628 (left) and M65/M66 (right) were taken with a vintage 1970 8-inch, f/7 Criterion newtonian reflector at prime focus. The 80mm was piggybacked on the 8-inch, and the cameras were controlled by APT. These optics were tracked using a Losmandy G-11 mount running a Gemini 2 control system and guided using PHD2 to control a ZWO ASI290MC planetary camera / auto-guider in an 80mm f/6 Celestron 'short-tube' refractor which itself was piggybacked on top of the 80mm apo.
Processed using a combination of DSS, PixInsight and PaintShopPro, as presented here the wide-field and 'close-up' images have only had their edges cropped slightly, and since they utilized identical cameras, they show the FOVs relative to each other for the 80mm & 8-inch rigs. After assembly the entire composite has been re-sized down to HD resolution (less than 1/6th it's original resolution) and the bit depth has been lowered to 8 bits per channel.
I'm hoping to re-visit this area in the future using one of my CCDs to emphasize the IFN permeating this region & the various gravitational disruption features within the galaxies themselves.