Super star cluster

Generally, SSCs have been seen to form in the interactions between galaxies and in regions of high amounts of star formation with high enough pressures to satisfy the properties needed for the formation of a star cluster. These regions can include newer galaxies with much new star formation, dwarf starburst galaxies, arms of a spiral galaxy that have a high star formation rate, and in the merging of galaxies. In an Astronomical Journal published in 1996, using pictures taken in the ultraviolet (UV) spectrum by the Hubble Space Telescope of star-forming rings in five different barred galaxies, numerous star clusters were found in clumps within the rings which had high rates of star formation. These clusters were found to have masses of about 10³ M_☉ to 10⁵ M_☉, ages of about 100 Myr, and radii of about 5 pc, and are thought to evolve into globular clusters later in their lifetimes. These properties match those found in SSCs.

Characteristics and properties

The typical characteristics and properties of SSCs:

• Mass ${\displaystyle \gtrsim }$ 10⁵ M_☉
• Radius ≈ 5 pc ≈ 10¹⁹ cm
• Age ≈ 100 Myr (although other sources state that observed SSCs have an age of 1 Gyr)
• Large electron densities ${\displaystyle n_{\text{e}}}$ = 10³–10⁶ cm⁻³ (this is a property of the HII region associated with the SSC)
• Pressures ${\displaystyle P/}$${\displaystyle k_{\text{B}}}$ = 10⁷–10¹⁰ K⋅cm⁻³. (this is a property of the HII region associated with the SSC)