'Hubble trouble' could deepen with new measurement of the universe's expansion

https://news.yahoo.com/hubble-trouble-could-deepen-measurement-113153160.html

The most accurate observation to date of distant stars that periodically change in brightness may spark a rethink of the rate at which the universe expands — perhaps by settling a longstanding problem in cosmology, or deepening it.

The observation confirms a disparity that exists between the two major methods of measuring how fast the universe is expanding, conforming with one but not the other, a new study reports.

Researchers with the Stellar Standard Candles and Distances group used data collected by Europe's Gaia spacecraft to study Cepheid variable stars, which pulsate in a regular manner, providing a way of accurately measuring cosmic distances. The Cepheid star measurement technique expands on other methods, such as one that relies on observations of Type 1a supernovas.

The light output of supernovas, mammoth explosions that occur at the end of big stars' lives, is so uniform they are referred to as "standard candles" and form an important part of what astronomers call the "cosmic distance ladder." The Cepheid star distance measurement method adds another "rung" to that metaphorical ladder, and this new research has strengthened that rung.

"We developed a method that searched for Cepheids belonging to star clusters made up of several hundreds of stars by testing whether stars are moving together through the Milky Way," study co-author Richard Anderson, a physicist at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, said in a statement.


There are some stunning photos too.