Astronomers propose novel method of measuring galaxy distances

The universe consists of a whole lot of billions of galaxies, and for close by galaxies, distances are primarily measured by classical Cepheids and RR Lyrae (RR Lyr) stars.

RR Lyr stars are pulsating variable stars which might be 100 occasions brighter than our sun and greater than twice as previous. They can be utilized as a typical candle for measuring the distances of galaxies, as a result of tight relationship between their pulsation interval and luminosity on the identical elemental abundance.

Primarily based on this information, astronomers from the Nationwide Astronomical Observatories of the Chinese language Academy of Sciences (NAOC) proposed utilizing double-period RR Lyr stars to measure the distances of galaxies, with the space error of galaxies being optimized to 1–2%. Their research was printed in Nature Astronomy on June 19.

About 5% of RR Lyr stars pulsate with multiple interval. Double-period RR Lyr stars are distinctive as a result of the 2 intervals are related to stellar properties akin to mass and elemental abundance.

“We discover that the basic abundance may be represented by two intervals, and thus a period-luminosity relation unbiased of the basic abundance was established,” stated Dr. Chen Xiaodian, lead writer of the research.

In comparison with measurements of elemental abundance, measurements of interval are each simple and correct.

“Our work offers a way by which distance measurements of nearby galaxies may be obtained from photometry alone, with out counting on spectroscopic observations,” stated Dr. Deng Licai, a senior researcher at NAOC and co-author of the research. “It will improve the pattern of galaxies with high-precision distance by an element of 20 or extra.”

Double-period RR Lyr stars are precious probes that present not solely dependable distances but additionally details about elemental abundances.

Within the coming years, the China House Station Telescope and the Vera C. Rubin Observatory will uncover tens of 1000’s of double-period RR Lyr stars in close by galaxies. Utilizing a distance measurement technique primarily based on double-period RR Lyr stars, astronomers count on to see a 3D intuitive map of the Native Group and procure a high-precision Hubble fixed.