In just over a year, the James Webb Space Telescope (JWST) will launch and begin its observations of the cosmos. But preparation work on the science mission has already begun and astronomers are excited about what it might discover. One particular group hopes it will finally unlock the secrets of brown dwarfs.
Brown dwarfs are often referred to as failed stars. They are large objects, about 70 times the mass of Jupiter, too big to be a planet but not big enough to initiate nuclear fusion in their cores and become stars. Université de Montréal researcher Étienne Artigau is leading a team effort to use the JWST to study a special brown dwarf.
The object is known as SIMP0136 and is only 20 light-years from Earth. It is also all alone in the universe, with no companion star, making it ideal for observations. But due to the pesky effects of the atmosphere, ground-based telescopes have struggled to form a complete picture of the object based on its light spectrum.
“Very accurate spectroscopic measurements are challenging to obtain from the ground in the infrared due to variable absorption in our own atmosphere, hence the need for space-based infrared observation," Artigau explained in a statement. "Also, Webb allows us to probe features, such as water absorption, that are inaccessible from the ground at this level of precision.”
The goal of this project is to find out whether brown dwarfs form like stars, through the collapsing of gas clouds, or like planets, by accretion of material over time. SIMP0136 might be the perfect target for this search. It looks like a brown dwarf but it seems to be much lighter – about 13 times the mass of Jupiter. However, there’s a chance that SIMP0136 is not a brown dwarf at all, but rather a rogue planet, expelled from a star system some time ago. Its spectrum also shows variations that have been interpreted as clouds.
“The brown dwarf SIMP0136 has the same temperature as various planets that will be observed in transit spectroscopy with Webb, and clouds are known to affect this type of measurement; our observations will help us better understand cloud decks in brown dwarfs and planet atmospheres in general,” Artigau added.
The new observations will hopefully clarify the true nature of SIMP0136. The JWST is expected to be launched between March and June 2019.