A new method to detect planet within few months

Finding a planet with a 10 years orbit in a few months.

Image: UNIGE

To find and affirm the presence of a planet around stars other than the Sun, stargazers hold up until the point when it has finished three orbits. The method involves the detection of a dip in the luminosity of the host star at the time the planet passes. According to scientists, this is a very effective method while searching for exoplanets.

In any case, this exceptionally compelling strategy has its disadvantages since it can’t affirm the presence of planets at generally long periods (it is preferably suited for times of a couple of days to a couple of months).

To defeat this obstacle, a group of space experts under the heading of the University of Geneva (UNIGE) have built up a technique that makes it conceivable to guarantee the presence of a planet in a couple of months, regardless of whether it takes 10 years to orbit its star.

By analyzing data from the space telescope K2, one star showed a significant long-duration temporary decrease of luminosity, the signature of a possible transit, in other words, the passage of a planet in front of its star.

Helen Giles consulted recent data from the Gaïa mission to determine the diameter of the star referenced as EPIC248847494 and its distance, 1500 light-years away from the planet Earth. With that knowledge and the fact that the transit lasted 53 hours, she found that the planet is located at 4.5 times the distance from the Sun to the Earth and that consequently, it takes about 10 years to orbit once.

The key question left to answer was whether it was a planet and not a star. The Euler telescope of the UNIGE in Chile would provide the answer. By measuring the radial velocity of the star, which makes it possible to deduce the mass of the planet, she was able to show that the mass of the object is less than 13 times that of Jupiter — well below the minimum mass of a star (at least 80 times the mass of Jupiter).

Giles explained, “This technique could be used to hunt habitable, Earth-like planets around stars like the Sun. We have already found Earths around red dwarf stars whose stellar radiation may have consequences on life which are not exactly known.”

She believes that the strategy will not let scientists wait for several years to know whether the detected single transit is due to the presence of a planet.

This new method is described for the first time in the journal Astronomy & Astrophysics.