As 2020 draws to a close, NASA is celebrating the Hubble Space Telescope’s 30 years of service by releasing 30 newly processed images of galaxies, star clusters and nebulae from the Caldwell catalogue, compiled by Sir Patrick Moore, a collection of 109 amateur-accessible targets not included in Charles Messier’s familiar list. Over Hubble’s three decades in space, starting with launch in April 1990, astronomers have observed 98 of the objects on the Caldwell list and the updated catalogue now includes processed images of 87 (several targets were imaged more than once). The new composite image below is a closeup of Caldwell 45, or NGC 5248, a beautiful spiral galaxy in the constellation Boötes, that was captured by Hubble’s Wide Field Camera 3 and Wide Field and Planetary Camera 2 in visible, infrared and ultraviolet light. The glowing red clouds indicate regions where new stars are lighting up.
Two astronomy students from Leiden University have mapped the entire Milky Way Galaxy in dwarf stars for the first time. They show that there are a total of 58 billion dwarf stars, of which seven percent reside in the outer regions of our galaxy. This result is the most comprehensive model ever for the distribution of these stars.
It is known today that merging galaxies play a large role in their evolution, and the formation of elliptical galaxies in particular. However, there are only a few merging systems close enough to be observed in depth. The pair of interacting galaxies seen here — known as NGC 3921 — is one of these systems. But ‘close’ is a relative term: NGC 3921 lies 270 million light-years away.
This NASA/ESA Hubble Space Telescope image shows star clusters encircling a galaxy, like bees buzzing around a hive. The hive in question is the edge-on lenticular galaxy NGC 5308, located just under 100 million light-years away in the constellation of Ursa Major. On 9 October 1996, one of NGC 5308’s aging stars exploded as a spectacular Type la supernova.