Scientists propose a new method for measuring distances to galaxies
- June 20, 2023
- 0
The universe is made up of hundreds of billions of galaxies, and distances to neighboring galaxies are mainly measured by classical Cepheids and RR Lyr stars. RR Lyr
The universe is made up of hundreds of billions of galaxies, and distances to neighboring galaxies are mainly measured by classical Cepheids and RR Lyr stars. RR Lyr stars are pulsating variables that are 100 times brighter and more than twice as old as our Sun. They can be used as a standard candle to measure distances to galaxies because of the close relationship between their vibrational periods and their luminosity for the same number of elements.
Based on this information, astronomers at the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC) have proposed using the binary star periods of RR Lyr to measure distances to galaxies, with an optimized distance error of 1-2%. Their research has been published Nature Astronomy 19 June
About 5% of RR Lyr stars vibrate with more than one period. Binary period RR Lyr stars are unique because the two periods are associated with stellar properties such as mass and element abundance.
Lead author of the study, Dr. “We found that element excess can be represented by two periods, and thus we establish a relationship between period and luminosity independent of element excess,” said Chen Xiaodian. Compared to element number measurements, period measurements are simple and accurate.
NAOC senior scientist and study co-author Dr. “Our work provides a method by which distance measurements to nearby galaxies can be obtained using only photometry, without relying on spectroscopic observations,” said Dan Likai. “This will increase the sample of galaxies with high sensitivity distance by 20 times or more.”
Two-period RR Lyr stars are valuable probes that not only provide reliable distances but also element abundance information.
In the coming years, the China Space Station Telescope and Vera S. Rubin Observatory will discover tens of thousands of double-period RR Lyr stars in nearby galaxies. Using a distance measurement method based on the double period of RR Lyr stars, astronomers hope to see an intuitive three-dimensional map of the Local Group and obtain a high-precision Hubble constant. Source
Source: Port Altele
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