A Bar-Driven Resonance Ring in Hydra
NGC 2665 is a compact barred spiral galaxy in the constellation Hydra, distinguished by a luminous central bar that feeds two tightly wrapped spiral arms into an inner ring-like configuration. Dust lanes thread through the inner disk, while scattered blue star clusters and compact pink H II regions trace ongoing star formation along the arms, set against the warm golden glow of the older stellar population concentrated toward the center.
At a catalog-verified distance of approximately 100 million light-years, NGC 2665 spans roughly ~60,000 light-years across its faint outer halo. On the sky it is a small target, about ~2.0′ × ~1.5′, yet it carries a surprising amount of internal structure: a well-defined bar, layered dust features, bifurcated inner arms, and discrete star-forming knots embedded in the spiral pattern.
One of the more unusual features of this galaxy is its near-complete inner ring, formed where the bar-driven gas flow appears to pile up at a resonance radius, giving the system its distinctive floral geometry. Subtle arm asymmetries are visible, with one side showing slightly stronger dust contrast and star formation than the other, hinting at either mild tidal perturbation or long-term secular evolution within the disk. The bar itself is slightly offset from the photometric center of the outer disk, a trait often seen in dynamically evolving barred spirals.
The galaxy’s outer envelope fades gradually into the surrounding sky, preserving a soft extended halo without crushing faint structure, while the inner disk shows finely layered dust lanes and localized regions of active star formation. Beyond the main subject, the field is populated with numerous distant background galaxies, including several faint edge-on systems and compact ellipticals, adding depth and reinforcing the immense scale of the cosmic backdrop in which NGC 2665 resides.
Imaged in LRGB on my Planewave CDK 1000 at Observatorio El Sauce, Chile
Image acquisition and processing: Mike Selby