by While the James Webb Space Telescope has become very popular lately, its predecessor, the Hubble Space Telescope, continues to impress. this time of the galaxy NGC 6956, a near-perfect example of a barred galaxy located about 214 million light-years from Earth.
Barred galaxies, named after the very prominent “bar” of stars that cross the galactic core, are among the most common types of galaxies in the known universe, they make up about 70% of all galaxies (opens in new tab). Bar structures are also much more common in galaxies with active galactic nuclei, as gas and other material is fed into the galactic core along these bars.
This procedure helps to eventually destabilize the forearm (opens in new tab)however, as more mass is pumped into the galactic core, the more unstable the bar becomes, eventually softening the bar into the more traditional spiral formation— like that of NGC 2985 (opens in new tab) — which most people think of when they think of a spiral galaxy.
Related: The Best Hubble Space Telescope Images Ever!
According to a image description from NASA (opens in new tab), this latest photo of NGC 6956 was to examine Cepheid variable stars, which are stars whose brightness fluctuates between bright and dim at regular intervals. These periods of brightness and dimming are directly related to the true brightness of a star, we can calculate these variations of apparent brightness to the stars true brightness, which allows us to determine their distance from us.
This is a critical way for astronomers to determine the distance of extragalactic objects like NGC 6956, as there are few other ways to do it that we currently know. There are other interesting features of NGC 6956, such as a visible Type Ia supernova, which is the product of a white dwarf exploding as a result of the accretion of matter from a companion star.
This type of supernova is another key method for determining the distance of distant galaxies, since astronomers are able to measure how quickly a supernova dims to help measure its distance from Earth. And while accurately filling out the galactic map is useful in its own right, repeated measurements of the distance of these extragalactic objects are an important tool for understanding the current rate of expansion in the universe.
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