Astronomy: Star with exoplanet may be hurtling out of the Milky Way
A research team may have discovered a star with an exoplanet that is so fast that both will leave the Milky Way.
(Image: NASA/JPL-Caltech/R. Hurt (Caltech-IPAC))
A group of astronomers may have discovered a planetary system that races through the Milky Way at a speed of at least 1.9 million kilometers per hour. If this is confirmed, it would be the first known exoplanet orbiting a hyper-fast star, NASA quotes study leader Sean Terry from the Goddard Space Flight Center. The US space agency also points out that the star and its companion could be traveling much faster because we do not know how fast it is moving away from us. It may even exceed the escape velocity of our home galaxy of around 1.2 million km/h and be on its way into the intergalactic void. This would make them about twice as fast as the sun and its planets.
Alternative explanation, no less exciting
The pair was found back in 2011 by a stroke of luck: In the so-called microlensing effect, an object in front of a star ensures that its light rays are bent on their way to us in such a way that the star appears brighter or enlarged to us. A research team has discovered just such a change in archive data from the New Zealand Microlensing Observations in Astrophysics (MOA) project. The identified change in brightness therefore pointed to two celestial bodies. Depending on how far away both were from Earth, it was either a star with an exoplanet or a much closer solitary planet with a moon.
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Using data from the ESA Gaia space telescope, the research group then identified a candidate for the star. Based on its position in 2011 and 2021, they then determined its enormous speed. To really ensure that the star is part of the hyperspeed system, the team wants to target it again next year. If this is not the case, the theory of a lone planet with a moon would gain renewed momentum – no less exciting for researchers. However, the preferred theory now is that it is a star that has about 20 percent of the mass of our sun and is traveling with an exoplanet that is 29 times more massive than Earth. The discovery has now been published in The Astronomical Journal.
(mho)
