Washington: Ohio State University astronomers have said that the Triangulum Galaxy, otherwise known as M33, is actually 15 per cent further away from our galaxy than previously measured, which implies that the universe is bigger and older than earlier believed.
This means that the Hubble constant, a number that astronomers rely on to calculate a host of factors including the size and age of the universe, could be significantly off the mark as well, they said.
Astronomers said they came to this conclusion after they invented a new method for calculating intergalactic distances in a more precise and simpler method compared to the standard procedure used for calculating intergalactic distances.
Associate professor of astronomy at Ohio State University, Kris Stanek, said he and his colleagues didn't start this work in order to change the value of the Hubble constant. They just wanted to find a simpler way to calculate distances.
"The Hubble constant used to be the one parameter that we knew pretty well, and now it's lagging behind. Now we know some things quite a bit better than we know the Hubble constant. Ten years ago, we didn't even know that dark energy existed," said Professor Stanek in his paper to be published in the Astrophysical Journal.
For calculating the distance to a faraway galaxy using the Hubble constant, astronomers have to work through several complex steps of related equations, and incorporate distances to closer objects, such as the Large Magellanic Cloud.
"In every step you accumulate errors. We wanted an independent measure of distance — a single step that will one day help with measuring dark energy and other things," Stanek said.
For his research, Stanek studied M33 in optical and infrared wavelengths using telescopes of varying sizes, from the small one metre telescopes to the 10-metre telescopes at the Keck Observatory in Hawaii — the largest in the world, and checked and re-checked measurements normally taken for granted.
"Technologically, we had to be on the cutting edge to make this work, but the basic idea is very simple," he said.
Two of the brightest stars in M33, which are part of a binary system - meaning that the stars orbit each other - were studied in detail, and their masses measured. The stars were found to eclipse each other every five days, as seen from the earth.
Stanek said considering their mass, the stars appeared quite dim, which meant they were far away, for had they been nearer, they would have appeared brighter.
"The distance was 15 per cent farther than we expected: about three million light-years away, instead of 2.6 million light-years as determined by the Hubble constant. If this new distance measurement is correct, then the true value of the Hubble constant may be 15 per cent smaller and the universe may be 15 per cent bigger and older than previously thought," he explained said.
He said their margin of error was six per cent, and now he and his team were contemplating studying another star in the M33 system to further reduce that error.
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