An artist’s concept of the isolated planetary-mass object SIMP 0136. With new observations on NASA’s James Webb Space Telescope (JWST), Museum astronomers and collaborators have uncovered a complex atmosphere on a free-floating “super-Jupiter” that’s about 20 light years from Earth.
First discovered in 2006, the object SIMP 0136 is about 13 times the mass of Jupiter and spins extremely fast: a full rotation is just 2.4 hours. Because it doesn’t orbit a star, it is not classified as an exoplanet, but SIMP 0136 could be a rogue planet or a brown dwarf, an object with a mass between planets and stars.
Although it is not hot enough to give off enough visible light to see from Earth, SIMP 0136 is the brightest isolated planet or brown dwarf viewable from the Northern Hemisphere and is thought to be about 200 million years old.
Prior to the JWST observations, SIMP 0136 had been studied extensively using ground-based observatories and NASA’s Hubble and Spitzer space telescopes.
“SIMP 0136 has always been one of my favorite objects to study,” said Jackie Faherty, a senior research scientist in the Museum’s Department of Astrophysics and co-author on the new study, published recently in The Astrophysical Journal Letters. “From previous work we knew it was young, nearby, and low mass, and that the light from it varied widely. We suspected it was an object with turbulent weather patterns, but we needed JWST to help solve the mystery.”
To further investigate, a research team working out of the Museum applied for and was awarded time to use JWST, which can measure very precise changes in brightness over a broad range of wavelengths. They collected and analyzed measurements over two full rotation periods of SIMP 0136, disentangling the brightness patterns of hundreds of colors of infrared light coming from different parts of the object’s atmosphere.
The researchers found evidence for patchy cloud layers on SIMP 0136, including deep clouds with iron particles and higher clouds made of silicate, the primary ingredients in rocks on Earth. They also found high-altitude “hot spots” that could be related to auroras, when high-energy particles interact with the atmosphere, creating a phenomenon known on Earth as the Northern or Southern Lights. Their findings also hint that there could be large pockets of carbon monoxide and carbon dioxide or chemical reactions causing the atmosphere to change over time.
“We haven’t really figured out the chemistry part of the puzzle yet,” said principal investigator Johanna Vos, now at Trinity College Dublin, who began this work as a postdoc at the Museum. “But these results are really exciting because they are showing us that the abundances of molecules like methane and carbon dioxide could change from place to place and over time. If we are looking at an exoplanet and can get only one measurement, we need to consider that it might not be representative of the entire planet.”
The work provides insight into the four-dimensional (3D plus time) complexity of gas giants within and beyond our solar system.
“Many of the exoplanets discovered so far are gas giants, similar in ways to Jupiter,” said Museum postdoctoral fellow Genaro Suárez, one of the study’s co-authors. “Detailed characterization of objects like SIMP 0136 are essential as it’s far easier to study these isolated sources than a planet orbiting a bright star.”
Museum researchers are involved in multiple follow-up studies that will perform similar analyses on other isolated objects.
“JWST is ideally suited for studying weather patterns on worlds beyond Earth,” said Museum postdoctoral fellow and study co-author Niall Whiteford. “We hope this work will increase our understanding of how diverse planetary atmospheres truly are.”