Yale Astronomer Finds Universe may be Expanding Faster Than Originally Believed
A Yale astronomer working with a team of scientists has found that the universe might be expanding somewhat faster than most current calculations.
Professor Stephen Zepf said in a study published in Nature magazine Thursday (Sept. 23) that the team came upon this discovery by using a new determination of the intrinsic brightness of a certain class of stars, Cepheids, that are important for determining distances to other galaxies.
“These Cepheids are a little fainter than we thought, so this changes the distances to a whole host of other galaxies,” Zepf said. “The reason this is significant is that since Cepheids are used to calibrate the expansion of the universe, if they are fainter, then the universe is expanding slightly faster. If the universe is expanding slightly faster, then it might be a little younger than we thought.”
“Nearly all galaxies are moving away from us,” he added. “The question is whether this will keep going on forever or whether eventually the universe will have enough density to collapse back on itself.”
One of the primary challenges in astronomy is to determine how far away things are. One of the common ways to do this is to take a ‘standard candle’ - an object nearby for which the intrinsic brightness can be measured. Similar objects are then found in distant galaxies.
“You can tell how far away the galaxies are by how faint the standard candle is,” Zepf said. “It is like taking a lamp with a 60-watt light bulb and figuring out how far away the lamp is by how faint the light bulb appears to be.”
“What we have done is to observe Cepheid stars, which are the primary standard candles through which galaxy distances are determined and for which the distance is believed to be known very accurately by other means,” he said.
“We found that the Cepheid stars may be about 15 percent fainter than previously thought,” Zepf said. “This is analogous to finding out that the light bulb you thought was 60 watts is really only 50 watts, therefore the lamp is actually closer than you originally estimated.”
Media Contact
Office of Public Affairs & Communications: opac@yale.edu, 203-432-1345