Ohio State University researchers have found a way to measure distances to objects three times farther away in outer space than previously possible, by extending a common measurement technique.

They discovered that a rare type of giant star, often overlooked by astronomers, could make an excellent signpost for distances up to 300 million light years - and beyond.

Cepheid variables - giant stars that pulse in brightness - have long been used as reference points for measuring distances in the nearby universe, said Jonathan Bird, doctoral student in astronomy at Ohio State. Classical cepheids are bright, but beyond 100 million light years from Earth, their signal gets lost among other bright stars.

In a press briefing at the American Astronomical Society meeting in Pasadena, CA, Bird revealed that a rare and even brighter class of cepheid - one that pulses very slowly - can potentially be used as a beacon to measure distances three times farther than their classical counterparts.

This project is the latest in principal investigator Krzysztof Stanek’s effort to gauge the size and age of the universe with greater precision.

There are several methods for calculating the distance to stars, and astronomers often have to combine methods to indirectly measure a distance. The usual analogy is a ladder, with each new method a higher rung above another. At each new rung of the cosmic distance ladder, the errors add up, reducing the precision of the overall measurement. So any single method that can skip the rungs of the ladder is a prized tool for probing the universe.

"Ohio State University astronomers are using the Large Binocular Telescope to look for ultra long period cepheid stars in galaxies such as M81, shown here. The stars could offer a new way to measure distances to objects in the universe. (Credit: Image courtesy of Ohio State University.)"

Source: Ohio State University