This image includes NGC 2814, an irregular galaxy in the Holmberg 124 group, caught by the HubbleTelescope Credit: ESA/Hubble & & NASA, C. Kilpatrick
This Hubble Picture of the Week includes NGC 2814, an irregular galaxy that lies roughly 85 million light-years fromEarth In this image, which was caught utilizing Hubble’s Advanced Camera for Surveys (AIR CONDITIONER), the galaxy seems rather separated: aesthetically, it looks a little like a loose stroke of brilliant paint throughout a dark background.
However, looks can be tricking. NGC 2814 in fact has 3 close (in huge terms) stellar next-door neighbors: a side-on spiral nebula called NGC 2820; an irregular galaxy called IC 2458; and a face-on non-barred spiral nebula called NGC2805 Collectively, the 4 galaxies comprise a galaxy group called Holmberg124 In some literature, these galaxies are described as a group of ‘late-type galaxies’.
Clarifying Galactic Classifications
The terms ‘late-type’ describes spiral and irregular galaxies, while ‘early-type’ describes elliptical galaxies. This rather complicated terms has actually caused a typical mistaken belief within the astronomy neighborhood. It is still rather commonly thought that Edwin Hubble incorrectly believed that elliptical galaxies were the evolutionary precursors to spiral and irregular galaxies, which that is the reason ellipticals are classified as ‘early-type’ and spirals and irregulars are classified as ‘late-type’.
This mistaken belief is because of the Hubble ‘tuning fork’ of stellar category, which aesthetically reveals galaxy types following elliptical to spiral, in a series that might quickly be analyzed as a temporal advancement.
However, Hubble in fact embraced the terms ‘early-type’ and ‘late-type’ from much older huge terms for excellent categories, and did not imply to state that ellipticals were actually evolutionary precursors to spiral and irregular galaxies. In truth, he clearly stated in his 1927 paper that “the classification … [early and late] … describes place in the series, and temporal undertones are made at one’s peri’.”
Despite Hubble himself being rather emphatic on this subject, the misconception continues practically a a century later on, and maybe supplies an instructional example of why it is valuable to categorize things with easy-to-interpret terms from the outset!
