Hubble Space Telescope image of the spiral galaxy NGC 6956. Credit: NASA, ESA, and D. Jones (University of California– Santa Cruz); Processing: Gladys Kober (NASA/Catholic University of America).
Against a dark black backdrop, the blue swirls of spiral nebula NGC 6956 stick out radiantly. NGC 6956 is a disallowed spiral galaxy, a typical type of spiral galaxy with a bar-shaped structure of stars in its. This galaxy exists 214 million light-years away in the constellation Delphinus.
Researchers utilized NASAs Hubble Space Telescope to image NGC 6956 to study its Cepheid variable stars, which are stars that lighten up and dim at routine durations. Because the period of Cepheid variable stars is a function of their brightness, researchers can measure how bright these stars appear from Earth and compare it to their actual brightness to compute their distance. As a result, these stars are very helpful in figuring out the distance of cosmic things, which is among the hardest pieces of information to determine for extragalactic objects.
This galaxy also contains a Type Ia supernova, which is the explosion of a white dwarf star that was gradually accreting matter from a companion star. Like Cepheid variable stars, the brightness of these types of supernovae and how quickly they dim over time enables researchers to calculate their distance. Researchers can use the measurements obtained from Cepheid variable stars and Type Ia supernovae to refine our understanding of the rate of expansion of the universe, also called the Hubble Constant.
By NASAs Goddard Space Flight
December 27, 2022
