Torn by Tides: The Distorted Spiral of IC 4705
In the southern constellation Pavo, the peculiar spiral galaxy IC 4705 reveals the unmistakable signs of tidal disruption. Its spiral arms are flung outward into long, narrow streams—faint stellar jets that stretch into intergalactic space. These are not artifacts of imaging or processing: as noted by astronomer Courtney Seligman, who was uncertain if these extended features were blue plate artifacts or real, rather as confirmed in this image they are the result of powerful gravitational interactions that have pulled stars from the galaxy’s outer disk.
IC 4705 is classified as a peculiar barred spiral (SB(s)b pec) and lies around 154 million light-years away. It spans roughly 120,000 light-years across, with an apparent size of about 2.2 × 1.4 arcminutes. The dusty core and disturbed arms, dotted with subtle hints of star formation, suggest a dynamic past—possibly a recent close encounter or minor merger. IC 4705 is one of the most unusual galaxies I have imaged, but it has not been previously imaged or studied in any depth.
Hovering above IC 4705 in the image is NGC 6868, an elliptical galaxy glowing with a smooth, golden light. Though they share the same field, NGC 6868 is closer, at a distance of about 129 million light-years. Its apparent size of 3.3 × 2.6 arcminutes translates to a true physical span of approximately 124,000 × 98,000 light-years, placing it among the more substantial elliptical galaxies. Its tranquil, rounded form stands in stark contrast to the chaotic profile of IC 4705 below.
Imaged in LRGB on my Planewave CDK 1000 at Observatorio El Sauce, Chile.
Image acquisition and processing: Mike Selby