A wonderful collection of galaxies and supernovae photographed by Hubble

This set of NASA/ESA Hubble Space Telescope images taken between 2003 and 2021 shows host galaxies of Cepheid variable stars and Type Ia supernovae. These two celestial phenomena are crucial tools that astronomers use to determine astronomical distance and are used to improve the measurement of the Hubble constant, the rate of expansion of the universe.

Each image in this particular collection features a spiral galaxy hosting Cepheid variables and a special class of supernovae, two seemingly fascinating stellar phenomena that don’t have much in common but are very useful to astronomers.

at Cepheid variable stars They are pulsars that light up and dim regularly.

at Type Ia supernova They are catastrophic explosions that signal the death of a hot, dense white dwarf star.

From the wide range of Cepheid and supernova variables in galaxies observed by Hubble, in its three-decade quest to accurately measure the rate of expansion of the universe, was selected (top to bottom and left to right):

NGC 7541, NGC 3021, NGC 5643, NGC 3254, NGC 3147, NGC 105, NGC 2608, NGC 3583, NGC 3147, Mrk 1337, NGC 5861, NGC 2525, NGC 1015, UGC 9391, NGC 691, NGC 76742, NGC 5468, NGC 5917, NGC 4639, NGC 3972, Antenna Galaxies, NGC 5584, M106, NGC 7250, NGC 3370, NGC 5728, NGC 4424, NGC 1559, NGC 3982, NGC 1448, NGC 4680, MGC 1365, NGC 1365, NGC 7329 and NGC 3447.

Measure the distance to a celestial body

Astronomers can use these two phenomena to measure how far away a celestial body is, which is a major challenge for astronomers. It can be difficult to distinguish between dark objects that are relatively close to the ground and bright objects that are far away.

To help overcome this challenge, astronomers have developed what’s known as the cosmic distance ladder, a series of methods for determining distances, arranged in order of relative measurable distances.

Two important steps on this ladder are the Cepheid variables and the supernova: Cepheid variables because the period they pulsate can be used to calculate distance, and supernovae because each type Ia supernova explosion always has the same luminosity, which means the glow emanating from Earth and visible from it can be used to determine afterwards.

All galaxies in this group host Cepheid variable stars and have had at least one Type Ia supernova explosion in the past 40 years. One of the galaxies, NGC 2525, contained a supernova captured in real time.

One of Hubble’s main scientific goals: to measure the expansion rate of the universe

Even before its launch, one of the main scientific goals of the Hubble telescope was to observe Cepheid and supernova variables. These notes can help A measure of the expansion rate of the universe, a value astronomers call the Hubble constant. Generations of astronomers have tuned this value over the course of nearly 30 years using data from more than 1,000 hours of Hubble’s work.

When Hubble was launched in 1990, the expansion rate of the universe was so uncertain that its age may not reach 8 billion years or 20 billion years.

After 30 years of hard work using the extraordinary observing power of a telescope, several teams of astronomers have managed to achieve a more accurate rate of just over 1% – a number that can be used to predict that the universe will double in size in 10 billion years.

Recently, a team of astronomers called SH0ES used observations of every supernova seen by Hubble over the past 30 years — including those in the galaxies pictured here — to determine the value of the Hubble constant as 73.04 ± 1:04 km – 1 Mpc. -1.

“This is what the Hubble Space Telescope was built for. We get the standard measurement of the universe from telescopes,” says Johns Hopkins University Nobel laureate Adam Reese, who leads the SH0ES team. “This is a Hubble masterpiece.”

Rees’ team’s paper, to be published in the Special Focus issue of The Astrophysical Journal, points out how the largest – and perhaps the last – update of the Hubble constant is complete.

From the wide range of Cepheid and supernova variables in galaxies observed by Hubble, in its three-decade quest to accurately measure the rate of expansion of the universe, was selected (top to bottom and left to right):

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