Astronomers using the Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope have captured a stunning new image of the spiral galaxy NGC 3021.
This is a Hubble Space Telescope photo of NGC 3021. Image credit: NASA / ESA / A. Riess, STScI.
NGC 3021, also known as UGC 5280 or SDSS J095057.14+333313.0, is approximately 100 million light-years away in the direction of the constellation Leo Minor.
Among many other types of stars, NGC 3021 contains Cepheid variable stars.
These stars pulsate at a rate that is closely related to their intrinsic brightness, so measurements of their rate of pulsation and their observed brightness give scientists enough information to calculate the distance to the galaxy itself.
Cepheid variables are also used to calibrate an even brighter milepost marker that can be used over greater distances, a Type Ia supernova.
One of these bright supernovae was observed in the galaxy in 1995.
In 2009, this supernova, cataloged as SN 1995al, was used to refine the measurement of what is known as the Hubble constant.
The value of this constant defines how fast the Universe is expanding and the more accurately we know it the more we can understand about the evolution of the Universe in the past as well as in the future.
So, there is much more to NGC 3021 than just a pretty spiral.
