Measuring tape of the universe: Researchers gain new insights into Cepheids
Cepheid stars are an aid for astronomers due to their luminosity and regular expansion. Now there are new findings about them.
RS Puppis is a Cepheid star, 200 times larger than the sun. It is located 6500 light years away from Earth.
(Image: NASA's Goddard Space Flight Center)
Researchers have succeeded in taking more precise measurements of pulsating Cepheid stars and gaining new insights into them. These very common and very bright giant stars are very easy to observe from Earth and serve as a useful tool for the astronomical determination of distances, such as those of galaxies. They also allow conclusions to be drawn about the size of the universe and make it possible to measure its rate of expansion.
Cepheids are larger and brighter than the sun. They regularly expand and then contract again, causing them to brighten and dim periodically. These cycles last between a few days and several months. This rhythm enables astronomers to measure distances in space.
Hundreds of Cepheids studied
As part of the Velocities of Cepheids (VELOCE) project, hundreds of Cepheids were studied between 2010 and 2022. The findings of the researchers from the Swiss Federal Institute of Technology in Lausanne (EPFL) have now been published in the June issue of the journal Astronomy & Astrophysics.
The researchers used the Swiss Euler telescope in Chile and the Flemish Mercator telescope on La Palma (Spain) for their work. Using the high-resolution spectrographs on both telescopes, they were able to resolve and measure the spectral lines of starlight. With the help of the Doppler effect, the speed at which the stars move along our line of sight, the so-called radial velocity, was then recorded.
In total, more than 18,000 measurements were taken. The astronomers discovered a previously unknown variation in the stars as well as some Cepheids that belong to a binary star system. The researchers hope that the results will provide a more precise understanding of the Cepheids and the interactions that emanate from companion stars and partially eclipse the stars. This should also have a positive effect on the distance measurements.
(mki)