Copyright Mark Hanson
Description by Sakib Rasool
Towards the direction of Ursa Major in the sky, NGC 3077 is the unappreciated and forgotten third member of the M81 trio of galaxies along with M82. Consisting of chaotic and disordered structure, its appearance immediately hints at its turbulent history. A characteristic it has in common with M82 are multiple spidery tendrils of ionized hydrogen gas emanating outwards from its core. These were first discovered in 1974.
Classed as a starburst dwarf galaxy, NGC 3077 is relatively nearby at 12 million light years. A series of tidally disrupted structures with striking blue stars is debris scattered from previous gravitational encounters with the other trio members, most notably M81. This structure has been nicknamed the "Garland" by professional astronomers and was first detected in photographic plates in the 1980's. Signatures of star formation triggered by tidal interactions are present as the many HII regions interspersed within its structure and at least 36 separate HII regions have been catalogued.
Another unusual aspect of this perturbed galaxy is the subtle blue core, which is surrounded by a disk consisting of an older stellar population. Normally it is the other way round, spiral galaxies consist of a golden core with blue spiral arms. The strange distribution of stellar matter is an indicator of a massive starburst of new stars being formed near the core due to the raw material of star formation being centrally concentrated at the nucleus.
Optical images such as this one don't always show the full picture of the morphology and kinematics of galaxies and other instruments are utilised to detect different parts that belong to other areas of the electromagnetic spectrum. Observations with radio telescopes are able to map the distribution of neutral hydrogen gas (HI), which is invisible optically. Witin the past few decades, the HI gas content of the M81 trio has been studied in superb detail and consists of many streamers and bridges connecting M81 and NGC 3077 together. A huge HI tail is also associated with NGC 3077 and contains more neutral gas than the core.
"Stellar Winds Observatory" a/k/a Stan Watson Observatory at Dark Sky New Mexico
Planewave 24", LRGB-HA, 480,150,150,150,990