New Way to measure gravity on distant stars suggested by UBC Researchers

New Way to measure gravity on distant stars suggested by UBC Researchers

Researchers have devised a new technique of measuring gravitational pull at the surface of a distant star. The gravity related data is important in ascertaining the presence of life on planets that orbit the star. The interesting research project was led by University of Vienna's Thomas Kallinger. Researchers from University of British Columbia and astronomers from France, Australia and Germany were also part of the research team.

The research team claimed that their new method can measure gravity on distant stars with accuracy up to 4 percent. For distant stars and those which are too faint, current methods to measure gravity are ineffective. The size of distant stars can be accurately calculated using the current technique as gravity is dependent on mass and radius of stars.

The research paper has been published in journal Science Advances January 1 issue. The new gravity measurement technique has been termed autocorrelation function timescale technique.

A red giant star has much weaker pull compared to other stars and one may weigh up to 50 times lighter on a red giant star. The research team estimates that one would weight 20 times more on surface of Sun compared to weight on Earth.

Professor Thomas Kallinger of the University of Vienna used data from the Kepler space telescope - which is searching for other worlds like the Earth - to show that variations in the brightness of distant stars can give more accurate measurements of surface gravity.

Study co-author professor Jaymie Matthews from University of British Columbia said, “If you don't know the star, you don't know the planet. The size of an exoplanet is measured relative to the size of its parent star. If you find a planet around a star that you think is Sun-like but is actually a giant, you may have fooled yourself into thinking you've found a habitable Earth-sized world. Our technique can tell you how big and bright is the star, and if a planet around it is the right size and temperature to have water oceans, and maybe life.”

The method can be applied to data from these searches to help understand the nature of stars like our Sun and to help find other planets like our Earth, says Dr Kallinger. Future space missions will hunt for planets around distant stars that might be capable of harbouring liquid water oceans and perhaps life.

The new technique called the autocorrelation function timescale technique, or timescale technique for short, uses subtle variations in the brightness of distant stars recorded by satellites like Canada's MOST and NASA's Kepler missions.

Future space satellites will hunt for planets in the 'Goldilocks Zones' of their stars. Not too hot, not too cold, but just right for liquid water oceans and maybe life.

Since surface gravity depends on the star's mass and radius (just as your weight on Earth depends on its mass and radius), this technique will enable astronomers to better gauge the masses and sizes of distant stars. It will play an exciting role in the study of planets beyond the Solar System, many so distant that even the basic properties of the stars they orbit can't be measured accurately.



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