The Arp-Madore 2105-332 galaxy, located 200 million light-years away, is composed of strange emission line galaxies that are active in the star formation process. This image captures an interacting galaxy system known as Arp-Madore 2105-332, which is about 200 million light-years away in the constellation Microscope. Like Hubble's other recent "Pictures of the Week," this galaxy belongs to the Arp-Madore Catalog of Exotic Galaxies.
Arp-Madore 2105-332, captured in this Hubble Space Telescope image, is a peculiar galaxy system in the constellation Microscope. It is known as an emission line galaxy, indicating active star formation. It is included in the "Hubble Pictures of the Week", and the galaxies in the picture are named with astronomical coordinates. Image credit: ESA/Hubble and NASA, J.Dalcanton, Credits: L.Shatz
This excellent image also reveals several additional galaxies that are not related to this galaxy but are so coincidentally positioned that they appear to be forming a line toward the leftmost part of Arp-Madore 2105-332 (in this image). They are individually known as 2MASXJ21080752-3314337. The galaxy on the far right is called 2MASXJ21080362-3313196. These lengthy names are not easy to remember, but they actually contain valuable information: They are coordinates in a system of right ascension and declination widely used by astronomers to locate celestial objects.
Both galaxies are emission line galaxies. This simply means that when viewed with a spectrometer, the spectra of both galaxies show characteristic bright peaks, known as emission lines. This is different from, say, absorption line galaxies, whose spectra contain distinct gaps, known as absorption lines. Emission lines are produced when the gas temperature is very high, so there is enough energy to "excite" atoms and molecules to emit light. In other words, emission line galaxies have high energy and are likely to be hotbeds for star formation.
As with many galaxy types, classifying a galaxy as an emission-line galaxy does not preclude other descriptions of its other properties. For example, Arp-Madore 2105-332 is also a "peculiar" galaxy, reflecting the atypical shape of its two constituent galaxies.
Compiled source: ScitechDaily