- Written by Megan
Astronomers have discovered an aging star they believe has just consumed a planet!
The star involved is coming towards the end of its life and is expanding outwards, becoming a type of star called a Red Giant. This is a very similar process our own star, the Sun, will undergo when it runs out of fuel in around five billion years. This star has the catchy title of BD+48 740, but while it isn't easy to remember by name it does have two strange characteristics.
One planet has been discovered around this star, at least 1.6 times the mass of Jupiter, on an unusually oval (elliptical) shaped orbit. According to current theories, planetary orbits should settle into roughly circular paths by the time their star gets to the Red Giant stage, so this highly elliptical orbit is very unexpected. The final dive of an inner planet into the star could have given a gravitational push to this discovered planet responsible for throwing it into this strange orbit.
There is also far more lithium in BD+48 740 than expected in a star of this age as it is very easily destroyed within stars. This means we would expect relatively low levels of lithium to be present in an evolved star. The large quantities in this star could be explained by an engulfed planet releasing extra lithium into the star.
The probability of astronomers observing a star just after engulfing a planet are very small, so this chance discovery will reveal extra information about the possible fate of inner planets in our own solar system.
The image is an artist's impression of an exoplanet, credit to the European Sothern Observatory (ESO)