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A 3-D model of the Milky Way Galaxy using data from Cepheids

Astronomers generate the largest 3D model of Milky Way using Cepheid data

We do not possess a GPS system for our twisted and warped galaxy. As a result, astronomers have to be crafty for pointing our location among stars and producing maps of the Milky Way galaxy. Astronomers from the US and Europe successfully managed to create a 3D model of Milky Way galaxy which is based on the interstellar distance. The study has been published in the Science journal

It draws on the population of stars that are called Cepheids. They are massive, young, pulsing stars having brightness more than that of the Sun. The University of Warsaw ran a sky survey with the help of data from the Optical Gravitational Lensing Experiment from Las Campanas Observatory in Chile. Researchers managed to pick out 2,431 Cepheids through the thick dust and gas of Milky Way and used them for generating the map of the galaxy. 

Dorota Skowron, a researcher with Wroclaw University of Science and Technology and the study’s lead author said that the OGLE project observed the Milky Way’s galactic disk for a period of six years while capturing 206,726 sky images that contained 1,055,030,021 stars. In this they found the Cepheids population to be very useful for the purpose of map plotting since their brightness varies over time. 

This allowed the researchers to observe how bright the star actually is versus how it appears from the Earth. This difference between the two can inform us how far the star is from our Sun. With the help of this fluctuation, scientists produced the galaxy’s 3D model which confirmed the previous work that the galaxy is flared at the edges. They were able to determine the Cepheid’s age where the younger stars were closer to the center and older stars farther away from the galactic disk. 

With the simulation of star formation in the early Milky Way, scientists showed the evolution of the galaxy in past 175 million years with star formation in spiral arms resulting in distribution of Cepheids from 20 million to 260 million years old. Skowron hopes that the paper will be a good initial point for sophisticated modeling of our Galaxy’s past, as the Cepheids are a great testbed for checking the accuracy of the models. 

A study was earlier published in Nature Astronomy which looked at 1339 Cepheids and generated a comprehensive 3D map of Milky Way which found that our galaxy is twisted at the edges. It observed stars from the Wide-field Infrared Survey Explorer (WISE) of NASA. These two studies produced similar results which found about the warped edges of Milky Way. Both the studies relied on the fact that the Cepheids are present on our side of the Milky Way. An important question is whether there is a similar warp in the opposite side too.

Skowron does not think observing the other side will increase the probability of finding Cepheids. The future projects will observe the pulsing star found in our Galaxy called  RR Lyrae. They are present from an earlier time in the Milky Way and can provide another way of mapping the Galaxy. 

Journal Reference: Science journal