in New Research Released on July 24th NatureIn 2017, a team of 19 scientists from around the world reported the discovery of a new supergiant exoplanet orbiting the star Eps Ind A. Named Eps Ind Ab, the planet was observed by the James Webb Space Telescope (JWST) and has a mass at least six times that of Jupiter. With a temperature of about -280 Kelvin, Eps Ind Ab is the coldest exoplanet ever directly imaged.
Cool supergiants like Eps Ind Ab are difficult to spot because they’re so dim and much of the light they emit falls in the mid-infrared region of the electromagnetic spectrum, said co-author Elizabeth Matthews, a researcher at the Max Planck Institute for Astronomy. It’s difficult to study from EarthThat makes JWST and its telescopes and cameras that study exactly this part of the electromagnetic spectrum crucial to this discovery.
“Until JWST, we didn’t have a telescope that was large enough and sensitive enough at mid-infrared wavelengths to spatially separate the planet and the star,” Matthews says.
The existence of a giant planet orbiting Eps Ind A It was first speculated in 2019. Further predictions about its properties were published in two papers. February and July The year is 2023. But when the research team examined the JWST data, they discovered a planet that was completely different from what they had expected.
Eps Ind A was significantly larger and farther from its star than scientists had previously thought. But it also presented another mystery: The planet is extremely bright in the mid-infrared wavelengths studied by JWST, and, as Matthews says, “we couldn’t tell for sure what the planet was, so we had to look at it.” [it] Most models predict that a planet as luminous as Eps Ind Ab at these wavelengths would also be luminous at other wavelengths – specifically, one of the wavelengths at which the Eps Ind A system has been observed. has already been studied in detail.
These observations did not detect Eps Ind Ab, suggesting that it is not actually bright at 4µm wavelengths. The team speculates that this could be because the planet’s atmosphere is rich in compounds that absorb light in the 4µm range. Matthews thinks that carbon monoxide, carbon dioxide, and methane could be the main components of the model. If this theory is correct, the planet would be unexpectedly rich in such compounds, raising further questions about how planets form.
“It’s a little difficult to come up with a model for how a planet with so many heavy elements could form,” Matthews said.
But she cautions that more data is needed to confirm theories about the presence of these elements. The team hopes to study the planet’s atmosphere using JWST’s spectroscopic instrument, which can directly measure a planet’s atmospheric composition.
Eps Ind Ab is expected to be the subject of intensive study in the coming years. There are still unanswered questions about the planet itself, namely the composition and formation process of its atmosphere. But the fact remains that the probe will provide an opportunity to directly observe a relatively rare kind of exoplanet, making it an excellent source of real-world data for scientists to test their theoretical models.
“Most of the time in astronomy we can only measure the brightness of stars, brown dwarfs, and planets,” Matthews explains. “We often want to be able to infer the mass of those objects based on their brightness.”
To achieve this, scientists develop models that relate brightness to mass. These models simulate the formation and evolution of these objects, and Eps Ind Ab provided scientists with the first opportunity to test thermal evolution models at low temperatures. As the paper states, the results were promising: “The planet’s optimum temperature is consistent with theoretical thermal evolution models.”
Finally, Eps Ind Ab and its parent star are gravitationally bound in a system that the team describes as a “wide-separated brown dwarf binary.” Matthews says that both brown dwarfs likely formed at the same time and from the same material as Eps Ind Ab and its parent star. Now that we know that all four objects likely have the same origin, studying the two systems is “incredibly valuable for testing models of formation and evolution,” she says.
JWST promises to provide more information in this area as well, and observations of the brown dwarf will allow the team to compare the chemical composition of its atmosphere with that of Eps Ind Ab.
