Brilliant spiral galaxy spotted by Hubble in new image
While the James Webb Space Telescope has been getting a lot of attention lately, its predecessor is the Hubble Space Telescope continues to impress; this time from the galaxy NGC 6956, a near-perfect example of a barred galaxy about 214 million light-years away from Earth.
Striped galaxies, which take their name from the very prominent “bar” of stars that traverse the galactic core are among the most common types galaxies in the known universe, which make up an estimated 70% of all galaxies (opens in new tab). Rod structures are also much more common in galaxies with active galactic nuclei, as gas and other material is carried along these rods to the galactic core.
This process helps to eventually destabilize the beam (opens in new tab)however, the more mass directed towards the galactic core, the more unstable the bar becomes, eventually softening the bar to the more traditional spiraling – like that of NGC 2985 (opens in new tab) – what most people think of when they think of a spiral galaxy.
According to a image description by NASA (opens in new tab)this most recent photo of NGC 6956 was to view Cepheid variables variable stars, which are stars whose brightness alternates between bright and dim at regular intervals. These periods of brightening and dimming are directly related to a star’s actual brightness. We can calculate these variations in apparent brightness relative to the actual brightness of the star, which allows us to determine their distance from us.
This is a crucial way for astronomers to determine the distance of extragalactic objects such as NGC 6956, as there are currently few other ways to do this that we know of. There are other interesting features of NGC 6956, such as a visible Type Ia supernovawhich is the product of a white dwarf star exploding due to accreting matter from a companion star.
This type of supernova is another important method of determining the distance of distant galaxies, as astronomers can measure how fast a supernova dims to measure its distance from Earth. And while accurately filling in the galactic map is useful in itself, repeated measurements of the distance of these extragalactic objects are an important tool in determining the current velocity of expansion in the universe.
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