Astrophysicists discover extragalactic planets

Image of the gravitational lens RX J1131-1231 galaxy with the lens galaxy at the center and four lensed background quasars. It is estimated that there are trillions of planets in the center elliptical galaxy in this image. Credit: University of Oklahoma
Date:5 February 2018 Tags:, ,

Astrophysicists have discovered a group of planets beyond the Milky Way galaxy, for the first time, using microlensing.

Microlensing “is a form of gravitational lensing in which the light from a background source is bent by the gravitational field of a foreground lens to create distorted, multiple and/or brightened images, according to a definition supplied to Scholarpedia by the Australian National University’s Professor Penny D Sackett of the Research School of Astronomy and Astrophysics.  

Using this astronomical phenomenon – the only known method capable of discovering planets at truly great distances from the Earth – along with other detection techniques, a University of Oklahoma (OU) astrophysics team were able to discover extragalactic objects that range from the mass of the Moon to the mass of Jupiter.

“This is an example of how powerful the techniques of analysis of extragalactic microlensing can be. This galaxy is located 3.8 billion light years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario,” said OU postdoctoral researcher Eduardo Guerras. “However, we are able to study them, unveil their presence and even have an idea of their masses. This is very cool science.”

The discovery was made by Xinyu Dai, professor in the Homer L. Dodge Department of Physics and Astronomy, OU College of Arts and Sciences, along with OU postdoctoral researcher Eduardo Guerras, using data from the National Aeronautics and Space Administration’s Chandra X-ray Observatory, a telescope in space that is controlled by the Smithsonian Astrophysical Observatory.

“We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy,” said Dai. “These small planets are the best candidate for the signature we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine the mass.”

While planets are often discovered within the Milky Way using microlensing, the gravitational effect of even small objects can create high magnification leading to a signature that can be modeled and explained in extragalactic galaxies. Until this study, there has been no evidence of planets in other galaxies.

For this study, OU researchers used the NASA Chandra X-ray Observatory at the Smithsonian Astrophysical Observatory. The microlensing models were calculated at the OU Supercomputing Center for Education and Research.

Source: University of Oklahoma via ScienceDaily

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