- Astronomers created most complete ultraviolet light survey of galaxies in the local universe.
- The catalogue contains nearly 8,000 young clusters and 39 million stars.
- They gathered data from Hubble’s ‘Advanced Camera for Surveys’ and ‘Wide Field Camera 3’.
Astronomers mostly use ultraviolet light to detect hottest and youngest stars in the universe. These stars are extremely bright and have a short life. Using data from NASA’s and ESA’s Hubble Space Telescope, they have completed a survey named Legacy ExtraGalactic UV Survey (LEGUS).
LEGUS contains the data of 50 local galaxies not farther than 58 million light-years from our planet in both ultraviolet and visible light. This is a high-resolution, detailed catalogue of star forming galaxies in the nearby universe.
The catalogue has nearly 8,000 young clusters and 39 million stars that are over 5 times bigger than our Sun. Stars in the visible light pictures are between 1 million to many billion years old – the youngest ones (1 to 100 million years old) shine brightly in UV light.
So how exactly did they do this, what factors they preferred, what instrument did they use while making the catalogue, and how useful it will be? Let’s find out.
How Did They Selected Targets?
The international team of astronomers working on LEGUS selected galaxies based on their masses, abundances of materials heavier than helium and hydrogen, and star-formation rate. There were about 500 candidates, and Hubble Telescope resolved all of the selected galaxies into their main sections – stars and clusters of stars.
They collected data from Hubble’s ‘Advanced Camera for Surveys’ and ‘Wide Field Camera 3’. This gives in-depth information about huge stars and star clusters, and factors affecting their formation and development. Overall, the catalogue has all necessary resources one might need to understand the complex process of the origin and evolution of stars/galaxies.
Image credit: LEGUS
The team has developed computer models to help researchers interpret the detailed data in the star and cluster catalogs. Using this model, they can analyze how stars were formed in a particular galaxy or a set of galaxies. They can match the star formation with the properties of the galaxies, and derive the history of the galaxies. Moreover, one can detect the progenitor stars of supernovas using UV light images.
Source: European Space Agency
The catalogue will help researchers find a link between the formation of stars and massive structures, like spiral arms, which make up a galaxy. The distribution of these structures can be observed in the youngest stellar populations.
Image credit: LEGUS
One of the main goals of this survey is to analyze the physical mechanisms governing the stellar population distribution in different galaxies, by examining the link to massive galactic structures. In order to better understand the evolution of the galaxy, one needs to figure out the final connection between gas and star formation.
Researchers are trying to establish different connection between gas and star formation by observing the surrounding effects on star clusters. In addition to providing a better perspective of the local universe, this survey will help researchers interpret views of faraway galaxies, where UV lights from massive young stars are stretched to infrared wavelengths because of the expansion of the universe.
The James Webb Space Telescope (next generation of Hubble) will complement the LEGUS observations. It will have exceptional resolution and sensitivity, that will enable a wide range of studies across fields of cosmology and astronomy.