The telescope’s infrared observations of the exoplanet, HIP 65426 b, were revealed Thursday (September 1) in a paper published in the preprint database arXiv (opens in a new tab). The paper has not yet been peer-reviewed, but was discussed at a blog post on the NASA website (opens in a new tab).
The young planet is a “super-Jupiter,” meaning it is a gas giant that is more massive than Zeus — about six to eight times more massive, in fact. It orbits an A-type star about twice its size sun and about 349 light years from Earth in the constellation Centaurus.
“This is an important moment for a number of reasons,” Aarynn Carter, lead author and postdoctoral researcher at the University of California, Santa Cruz, told Live Science. “First, this is the first time we’ve ever imaged a planet beyond 5 microns” in wavelength.
Micrometers or micrometers are how scientists measure wavelengths of light in the electromagnetic spectrum. Infrared light has wavelengths longer than these visible light and wins at the start at 0.75 microns. Unlike any other space telescope, JWST can cover the range from 0.6 to 28 micrometers. In comparison, the Hubble Space Telescope only covers infrared red up to 2.5 microns, while ground-based telescopes go beyond 2.2 microns. Thus, JWST gives astronomers a much wider view of objects than was previously possible.
“We can cover the full spectrum of light wavelengths of these objects and obtain tight constraints on their luminosity and, in turn, other properties such as mass, temperature and radius,” Carter said. That kind of detailed analysis will be published in the future, he said.
Astronomers observed HIP 65426 b using seven filters, each of which allows a specific wavelength of infrared light to pass through. The telescope’s accuracy surprised them.
“The telescope is more sensitive than we expected, but it’s also very stable,” Carter said. Carter’s work showed that JWST is powerful enough to detect smaller exoplanets than ever before.
“Previously we were limited to super-Jupiter detections, but now we have the ability to image Uranus- and Neptune-like objects for the right targets,” Carter said.
Direct imaging of exoplanets is difficult because planets are easily lost in a star’s glare. JWST blocks the glare using a disc called a coronagraph in both the near-infrared camera and the mid-infrared instrument. HIP 65426 b was initially spotted in July 2017 (opens in new tab) in short infrared wavelengths of light by scientists using the European Southern Observatory’s Very Large Telescope (VLT) in Chile and was chosen to test JWST’s accuracy and find the best way to directly image exoplanets in the mid-infrared light.
“We chose this star as we knew it had a well-established planet that would be ripe for direct imaging and therefore would be an excellent first target for testing the JWST coronagraphs,” Sasha Hinkley, associate professor in the Department of Physics and Astronomy. at the University of Exeter and principal investigator for one of the 13 JWST Early Release Science Programs, he told Live Science. The JWST Early Release Science Programs during the first five months of JWST’s science activities are designed to provide scientists with immediate access to early data from specific science observations.
HIP 65426 b is easier to distinguish from its host starlight because it is 100 times farther from its host star than Earth is from the sun, but it still over 10,000 times fainter than its host star (opens in new tab) in the near infrared.
“This is a particularly exciting start to this new era of conception photons directly from exoplanet atmospheres at entirely new wavelengths that will last for the next 20 years or so,” Hinckley said.
Originally published in Live Science.
