A team of astronomers led by the University of Arizona has discovered a planet in a unique position between 3 stars.
If you thought Luke Skywalker’s home planet, Tatooine, was a strange world with its two suns in the sky, imagine this: a planet where you’d either experience constant daylight or enjoy triple sunrises and sunsets each day, depending on the seasons, which happen to last longer than human lifetimes.
Such a world has been discovered by a team of astronomers led by the University of Arizona , using direct imaging. The planet, HD 131399Ab, is unlike any other known world – on by far the widest known orbit within a multi-star system. The discovery is published online by the journal Science.
Located about 340 light years from Earth in the constellation Centaurus, HD 131399Ab is believed to be about 16 million years old, making it one of the youngest exoplanets discovered to date, and one of very few directly imaged planets. With a temperature of 850 Kelvin (about 1,070 degrees Fahrenheit or 580 degrees Celsius) and weighing in at an estimated four Jupiter masses, it is also one of the coldest and least massive directly imaged exoplanets.
HD 131399Ab is one of the few exoplanets that have been directly imaged, and it’s the first one in such an interesting dynamical configuration.
The planet marks the first discovery of an exoplanet made with SPHERE, one of the world’s most advanced instruments dedicated to finding planets around other stars. SPHERE, which stands for the Spectro-Polarimetric High-Contrast Exoplanet Research Instrument, is sensitive to infrared light, making it capable to detect the heat signatures of young planets, along with sophisticated features correcting for atmospheric disturbances and blocking out the otherwise blinding light of their host stars. The instrument is part of the Very Large Telescope operated by the European Southern Observatory in northern Chile.
Although repeated and long-term observations will be needed to precisely determine the planet’s trajectory among its host stars, observations and simulations seem to suggest the following scenario: At the center of the system lies a star estimated to be eighty percent more massive than the sun and dubbed HD 131399A, which itself is orbited by the two remaining stars, B and C, at about three-hundred AU (one AU, or astronomical unit, equals the average distance between the earth and the sun). All the while, B and C twirl around each other like a spinning dumbbell, separated by a distance roughly equal to that between our sun and Saturn .
Planets in multi-star systems are of special interest to astronomers and planetary scientists because they provide an example of how planet formation functions in these more extreme scenarios
