NGC 3628. Hamburger Galaxy

 

 

 

 

NGC 3628, often referred to as the Hamburger Galaxy is an edge-on spiral galaxy located in the constellation Leo, approximately 37 million light-years from Earth. Discovered by William Herschel in 1784, it forms a striking trio of interacting galaxies known as the Leo Triplet, alongside Messier 65 and Messier 66.

This galaxy exhibits a distinctive wide equatorial dust lane, slicing across its luminous disk and giving rise to its hamburger-like appearance. Beyond its photogenic appearance, NGC 3628 also possesses a remarkable tidal tail (star stream) extending some 300,000 light-years, likely sculpted by gravitational interactions with M 65 and M 66. In this image, only a fragment of the tail can be seen. The star stream is rich in young star clusters and starburst regions, hallmarks of such dynamic encounters.

NGC 3628 is not only aesthetically attractive but also serves as an astrophysical laboratory. Spectroscopic studies also reveal an unusual kinematic decoupling within the system: the galaxy’s stars orbit in the opposite direction to its gas—a possible consequence of prior merger or accretion episodes. Furthermore, radio observations in the CO transition have found a “small” molecular outflow in the galaxy’s core. According to A. L.Tsai et al. (2018), this outflow spans 370–450 parsecs, carries around 2.8 × 10⁷ M☉ of molecular gas, and expels it at roughly 90 km/s—a clear sign of important starburst activity near the center of the galaxy. This activity is in an early evolutionary stage.

Additional high-resolution radio and X-ray studies (2023) have detected multiple compact radio sources—likely supernova remnants—in the central few hundred parsecs. One of these appears to be a recently formed radio supernova.