IC 1613 is a very clean dwarf galaxy

The dwarf galaxy IC 1613 photographed by the OmegaCAM on ESO's VST (Image ESO)
The dwarf galaxy IC 1613 photographed by the OmegaCAM on ESO’s VST (Image ESO)

The OmegaCAM camera mounted on ESO’s VST (VLT Survey Telescope) was used to take a picture of the dwarf galaxy IC 1613. It has the distinction of being really clean, meaning that it contains very little dust while most galaxies contain dust clouds or are even full of it. The very low dust content of IC 1613 allows astronomers to observe its inside and is therefore an excellent target for astronomy and astrophysics studies.

The galaxy IC 1613, also known as LEDA 3844, UGC 668, DDO 8, PGC 3844 or Caldwell 51, was discovered in 1906 and is located about 2.4 million light years from Earth. It’s part of the Local Group, a group of more than 50 galaxies that includes the Milky Way and Andromeda, the two largest galaxies among those that belong to it. It’s not considered a galactic cluster for the reduced amount of galaxies that make up this group.

Astronomers discovered various peculiarities in the galaxy IC 1613 because in addition to the low amount of dust it has an irregular shape. Generally galaxies can be categorized into specific classes but there are some that don’t have shapes that can allow this type of classification.

For astronomical studies, the most interesting feature of the galaxy IC 1613 is the scarcity of dust that makes it very clear. The dust makes observations difficult by absorbing at least part of the light emitted by stars with the result that sometimes we can see only certain frequencies. The lower the absorption the higher the precision of the observations and those of the stars within IC 1613 are excellent.

Astronomers determined the distance of the galaxy IC 1613 with a good approximation thanks to two types of variable stars: Cepheids and RR Lyrae. These are two types of stars that pulsate rhythmically and grow in size and brilliance at fixed intervals. Their characteristics can be exploited to measure distances and the ability to observe them clearly is a big help.

Type Ia supernovae are also among what are called “standard candles” because they allow to calculate cosmic distances. Supernovae are extremely bright but the type Ia ones are less common than variable stars. Good observations such as those possible in the galaxy IC 1613 are still useful.

The case of the galaxy IC 1613 is yet another one of spectacular images that at the same time help astronomers. This dwarf galaxy has in fact played a role in the advancement of techniques for measuring cosmic distances exactly because its clarity allows excellent observations.



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