hr8799
NASA’s James Webb Space Telescope has provided the clearest look in the infrared yet at the iconic multi-planet system HR 8799. The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
NASA’s James Webb Space Telescope has provided a direct look at the multiple gas giant planets within the iconic planetary system HR 8799. Located 130 light-years away, this system is young—about 30 million years old—and could offer clues on planet formation.
The HR 8799 system has four giant planets: HR 8799 b, c, d, and e. The observations suggest that these planets are hot from their tumultuous formation. They emit large amounts of infrared light, giving vital data about their formation.
Also, the planets are enriched with carbon dioxide, which means they must have formed much like Jupiter and Saturn. They have solid cores that pull gas from within a protoplanetary disk. This process is referred to as core accretion.
The findings further demonstrate that Webb can determine the chemical makeup of exoplanet atmospheres using imaging. This method enhances Webb’s advanced spectroscopic tools, which can analyze and identify the components of these atmospheres.
Webb’s NIRCam (Near-Infrared Camera) captured this image of 51 Eridani b (also referred to as 51 Eri b), a cool, young exoplanet that orbits 890 million miles from its star, similar to Saturn’s orbit in our solar system. The 51 Eridani system is 97 light-years from Earth. This image includes filters representing 4.1-micron light as red. The background red in this image is not light from other planets, but a result of light subtraction during image processing. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
William Balmer of Johns Hopkins University in Baltimore said, “By spotting these strong carbon dioxide features, we have shown a sizable fraction of heavier elements, like carbon, oxygen, and iron, in these planets’ atmospheres. Given what we know about the star they orbit, that likely indicates they formed via core accretion, which is an exciting conclusion for planets that we can directly see.”
“Our hope with this kind of research is to understand our solar system, life, and ourselves compared to other exoplanetary systems so that we can contextualize our existence. We want to take pictures of other solar systems and see how they’re similar or different compared to ours. From there, we can try to understand how weird our solar system is—or how normal.”
Webb’s NIRCam (Near-Infrared Camera) coronagraph played a pivotal role in capturing images of HR 8799 and 51 Eridani by blocking the overwhelming light of bright stars, enabling the detection of planets that would otherwise remain obscured.
With this advanced technology, researchers were able to search for infrared light emitted by the planets at wavelengths that specific gases absorb. This investigation revealed that the four planets orbiting HR 8799 possess a greater abundance of heavy elements than previously understood.
Laurent Pueyo, an astronomer at the Space Telescope Science Institute in Baltimore, who co-led the work, said, “We have other lines of evidence that hint at these four HR 8799 planets forming using this bottom-up approach. How common is this for planets we can directly image? We don’t know yet, but we’re proposing more Webb observations to answer that question.”
Journal Reference:
William O. Balmer, Jens Kammerer, Laurent Pueyo, Marshall D. Perrin, Julien H. Girard, Jarron M. Leisenring, Kellen Lawson, Henry Dennen. JWST-TST High Contrast: Living on the Wedge, or NIRCam Bar Coronagraphy Reveals CO2 in the HR 8799 and 51 Eri Exoplanets’ Atmospheres. The Astronomical Journal. DOI: 10.3847/1538-3881/adb1c6
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