Study based on 30 years of Hubble data provides the most accurate measurement of the expanding speed of the universe

A study published by the prepress server arXiv and already accepted for publication by The Astrophysical Journal brings a NASA report based on 30 years of Hubble data, which astronomers refer to as ” masterpiece(the largest work) of the space telescope. These data provide the most accurate measure of the rate of expansion of the universe.

We have collected 30 years of data from the Hubble Telescope to arrive at the most accurate measure of the rate of expansion of the universe. Photo: Whitelion61 /

The astronomical scientific community has known for more than a century that the universe is expanding, thanks to observations of the increasing distance between galaxies. The speed at which they move relative to their distance from Earth is called the “Hubble constant”, and measuring this value was one of the main tasks of the Space Observatory.

To measure the Hubble constant, astronomers study distances to objects whose brightness is well known – so the dimmer it looks, the farther away it is. For objects relatively close to the Milky Way or nearby galaxies, this role is filled by the Cepheids, a class of stars pulsing in a predictable pattern. For greater distances, scientists use so-called Type Ia supernovae – cosmic explosions with a well-defined brightness.

Over the last few decades, measurements of these objects have calculated the Hubble constant to be about 70 km per second. second per megaparsec (/ s / Mpc). Basically, a galaxy a megaparsec (about 3.3 million light-years) from Earth will move away at 70 km per second, and that speed increases by 70 km / s for every megaparsec away.

The Hubble Telescope provides the most complete catalog of cepheids and supernovae

For the new study, a team of scientists analyzed the most comprehensive catalog of these objects to date to make the most accurate measurement of the Hubble constant yet. This was done by studying 42 galaxies containing both Cepheid and Type Ia supernovae.

A study based on 30 years of Hubble data
This collection of images from NASA’s Hubble Space Telescope shows host galaxies for the Cepheid and supernova variables, two celestial phenomena considered to be crucial tools for determining astronomical distances, and which have been used to refine Hubble’s measurement constantly. Photo: NASA, ESA, Adam G. Riess (STScI, JHU)

“This is what the Hubble Space Telescope was built for using the best techniques we know,” said team leader Adam Riess, an astronomer at the Space Telescope Science Institute (the Hubble Scientific Operations Center and the James Webb Telescope) and a fellow of the National Academy of Sciences. “It is enough masterpiece by Hubble ”.

Based on these readings, the Hubble constant calculated by the team was 73.06 km / s / Mpc. This reduces the margin of error to only 1.4%, a much more accurate measurement than the previous ones. This new precision could help astronomers improve models of cosmology, including better estimates of how old the universe is and what its future may hold.

However, there is a large unknown left. The standard model for cosmology predicts that the Hubble constant should be much slower – around 67.5 km / s / Mpc. This has even been supported by observations of the background radiation left behind by the Big Bang. The deviation seems to be related to the point in the universe we are looking at – in our local region the constant is faster, while in the distant universe it is slower, even after taking into account known acceleration of expansion.

It may seem like the simplest explanation is that someone has made a mistake, but oddly enough, both cases are pretty solid. Fortunately, we may not have to wait long for new clues to the mystery, as James Webb will be able to study the same markers at greater distances and at higher resolution than Hubble.

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