Amargosa is the designation of a star, which was brought to collapse by Dr. Tolian Soran's Trilithium weapon, which was launched from the Amargosa observatory in 2371.
By the collapse of the Amargosa sun, Soran achieved a flight path alteration of the Nexus, which passed the star and was influenced by the changed gravitational conditions in the Amargosa system just like the Federation starship USS Bozeman. The collapse of Armagosa, however, also caused a blast wave, which annihilated everything in the system, including the observatory.