An exoplanet that is thirteen times bigger than Jupiter and 155 light years from our solar system was discovered by an international team of researchers.
The massive distance at which the exoplanet is located from its star GU Psc gave the researchers an opportunity to accurately detect and clearly view the gas giant. The discovery was made by observing data from the Observatoire Mont-Mégantic (OMM), the Canada-France-Hawaii Telescope (CFHT) and the W.M. Keck Observatory.
GU Psc is a star that has a mass three times less than that of the Sun. GU Psc b, the newly discovered exoplanet, is 2,000 times farther from its star than the Earth is from the sun, 67 times farther than Neptune and 50 times farther than Pluto. This makes it the most distant planet from its star ever discovered. Comparatively, this planet takes approximately 80,000 Earth years to complete one orbit around its star.
The planet was discovered when researchers were studying GU Psc because the star had just been identified as a member of the young star group AB Doradus.
Researchers usually look around young stars that are less than 100 million years old because these stars are prime targets for discovering new exoplanets. However, researchers clarify that this doesn't mean that there are plenty of planets like GU Psc b, waiting to be discovered.
"GU Psc b is a true gift of nature. The large distance that separates it from its star allows it to be studied in depth with a variety of instruments, which will provide a better understanding of giant exoplanets in general," said René Doyon, co-supervisor of Naud's thesis and OMM Director in a statement.
After a planet is detected, researchers use theoretical models of planetary evolution to determine the cosmic body's mass and other characteristics like temperature. For this discovery, researchers used the light spectrum of GU Psc b obtained from the Gemini North Observatory and compared it to one such theoretical model. They found that the planet has a mass that is around 13 times that of Jupiter and a temperature of 800°C. An analysis of "fingerprints" in different colors of light emitted by the planet revealed that it is relatively young.
This excessively large mass has given rise to speculations that the unusual object may not be a planet at all. It may instead qualify as a brown dwarf or a "failed star", which is too small to ignite the nuclear reactions that power stars. Whatever be the case, the discovery still brings with it a series of possibilities.
If the object is a planet, it debunks previous theories suggesting planets only form from the "planetary disk" of dust near a star. If it's a brown dwarf, it shrinks the known size limit of objects that can form in a way similar to the way stars form.
The high temperatures rule out the possibility of the planet being habitable, even after it cools to a more comfortable temperature.
"What could be habitable is a moon around that planet," Doyon told CBC News. He added that Jupiter's moon Europa would have liquid water on its surface if it orbited Gu PSc b. However, the comfortable conditions wouldn't last long, as the planet would continue to cool rapidly as it got older.
Researchers of a new study are now starting a project to observe several hundred stars and detect planets lighter than GU Psc b with similar orbits.
Details of the discovery were published online in The Astrophysical Journal.
