A Hyper Velocity Star Found with an Exoplanet Hanging on for Dear Life

Hypervelocity stars have been seen before but NASA scientists have just identified a potential record-breaking exoplanet system. They found a hypervelocity star that has a super-Neptune exoplanet in orbit around it. This discovery could reshape our understanding of planetary and orbital mechanics. Understanding more about these fascinating high velocity stars challenges current models of stellar evolution. However it formed, its amazing that somehow, it has managed to hang on to its planet through the process!

High-velocity stars travel through space at extraordinarily high speeds, often in excess of hundreds of kilometres per second. These rapidly moving stars are usually expelled from their galaxies due to gravitational forces, perhaps from close encounters with supermassive black holes or other stars. Some of them move so fast that they can break free from the Milky Way’s gravitational pull. It’s important to study them as they offer crucial insights into the dynamics of our Galaxy, interactions with black holes, and even the distribution of dark matter across the cosmos.

Details of the discovery were published in a paper that was authored by lead astronomer Sean Terry in The Astronomical journal. It tells of the discovery of what the team think is a super-Neptune world that is in orbit around a star with a low mass. The system is travelling at an estimated 540 kilometres per second! If it were aligned with our own Solar System and the star was where our Sun was, then the planet would sit somewhere between the orbits of Venus and Earth. Terry, who is a researcher at the University of Maryland and said “it will be the first planet ever found orbiting a hypervelocity star.” 

Finding objects like this in space is tricky. This object was first seen in 2011 following analysis of data from the Microlensing Observations in Astrophysics survey that had been conducted by the University of Canterbury in New Zealand. The study had been on the lookout for evidence for exoplanets around distant stars. 

The presence of a mass between Earth and a distant object creates these microlensing events. As such a mass passes between us and a star, its presence can be revealed through analysis of its light curve. In the 2011 data, the signals revealed a pair of celestial bodies and allowed the researchers to calculate that one was about 2,300 times heavier than the other. 

The 2011 study suggested the star was about 20 percent as massive as the Sun and a planet 29 times heavier than Earth. Either that, or it was a nearer planet about four times the mass of Jupiter, maybe even with a moon. To learn more about the object the team searched through data from Keck Observatory and the Gaia satellite. They found the star, located about 24,000 light years away so still within the Milky Way. By comparing the location of the star in 2011 and then ten years later in 2021, the team were able to calculate its speed. 

Having calculated the speed of the star to be around 540,000 kilometres per second, the team are keen to secure more observations in the years ahead. If it is around the 600,000 kilometres per second mark then it’s likely to escape the gravity of the Milky Way and enter intergalactic space millions of years in the future. 

Source : NASA Scientists Spot Candidate for Speediest Exoplanet System

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