New Webb images reveal the space telescope’s first exoplanet, first brown dwarf, and a stellar nursery teeming with activity.

Over the past week, the James Webb Space Telescope has captured both its first exoplanet and its first brown dwarf as well as photographed the firestorm of star formation in the Tarantula Nebula. Though all three celestial objects have been studied before, Webb provides details astronomers can’t get anywhere else.

The Planet

Image of star with call-out images of planet (fuzzy dot) next to star
This image shows the exoplanet HIP 65426 b in different bands of infrared light (3 microns in purple, 4.44 microns in blue, 11.4 microns in yellow, and 15.5 microns in red. A coronagraph blocks out the host star’s light; the star's position is marked in each image by a small white star. The bar shapes in the NIRCam images are artifacts of the telescope’s optics, not objects in the scene.
NASA / ESA / CSA / A. Carter (UCSC) / ERS 1386 team / A. Pagan (STScI)

Late last week, the Webb team released its first image of an exoplanet, a gas giant known as HIP 6542 b. It’s nothing like the giants in our solar system, with a mass between 6 and 12 times that of Jupiter and a distance from its host star that’s 10 times farther out.

Stars shine less brilliantly at infrared wavelengths, but even so this planet was still 10,000 times fainter than its star. Webb’s cameras have coronagraphs that help out by blocking the star’s brilliance. It also helps that the system is young, only 15 to 20 million years old, so the planet itself is still glowing from the heat of its formation.

“Obtaining this image felt like digging for space treasure,” says Aarynn Carter (University of California, Santa Cruz), who led the image analysis. “At first all I could see was light from the star, but with careful image processing I was able to remove that light and uncover the planet.”

Carter and his colleagues are now preparing a publication on their analysis for submission to a peer-reviewed journal.

The Brown Dwarf

Infrared spectrum of brown dwarf
This plot shows the infrared spectrum of VHS 1256 b. Elements and molecules leave their chemical fingerprints in the spectrum, shedding light on the brown dwarf's atmosphere. Colors highlight different wavelength bands; error bar are displayed in gray.
B. Miles et al (2022) /

In another first announced this week, Webb has observed its first brown dwarf, designated VHS 1256-1257 b, 72 light-years away in the constellation Corvus. This in-betweener is between 14 and 24 times Jupiter’s mass, so it’s a bit too big to be a planet but not massive enough to ignite longlasting fusion in its core. Like the exoplanet above, this system is also young at 200 million years old.

Webb took a spectrum of this world, revealing the chemical elements that make up what was previously seen to be a reddish atmosphere. The infrared spectrum, which spans 1 to 20 microns, shows evidence for methane, sodium, potassium, water, and carbon dioxide, as well as a thick layers of silicate clouds.

Brittany Miles (University of California, Santa Cruz) and colleagues have posted their study on the arXiv preprint server, but it has not yet undergone peer review.

The Tarantula

Tarantula Nebula in infrared looks more like a cavity surrounded by spider silk
In this mosaic image stretching 340 light-years across, Webb’s Near-Infrared Camera reveals tens of thousands of never-before-seen young stars in the Tarantula Nebula, shrouded in cosmic dust in previous observations. The most active region appears to sparkle with massive blue stars. Scattered among them are still-embedded stars, appearing red, yet to emerge from the dusty cocoon of the nebula.
NASA / ESA / CSA / STScI / Webb ERO Production Team

The Tarantula Nebula, also known as 30 Doradus, hosts the fiercest star formation in the Local Group of galaxies around the Milky Way. But it’s also fundamentally different from other nearby stellar nurseries, because its chemical composition shows a relative lack of “pollution” from the heavier elements that stars forge in their cores. In other words, this star-formation region acts like one in a far younger universe, and it has long captured astronomers’ attention for that reason.

The new and forming stars burn 161,000 light-years away in the Large Magellanic Cloud, the largest satellite galaxy of the Milky Way, and received its name from the spider-leg clouds seen in visible observations. But infrared images reveal something different.

Massive young stars, shining like sapphires in the center, blow out a cavity in the surrounding dust-and-gas cloud that gave them birth. Denser parts of this cloud have resisted the young stars’ push and were shaped instead into pillars pointing toward the center. At infrared wavelengths, Webb reveals the protostars hidden within these pillars. For now, they are biding their time, gaining mass. Once these infant stars “turn on,” igniting nuclear fusion in their cores, their shine will push out the surrounding gas, changing the nebula’s shape.


Image of Rod


September 9, 2022 at 11:34 am

Nice, good to see reports in S&T providing some views of JWST is looking at 🙂 I note here about the exoplanet shown. In the paper, problems with the size of the exoplanet imaged is discussed near the end of the paper. “• Atmospheric Model Fitting: Using a BT-SETTL atmospheric forward model we are able to fit all data, in addition to the majority of ground-based observations to within 2σ...Compared to a fit excluding the JWST data, this corresponds to a factor of ∼3 improvement in the precision of the radius and bolometric luminosity. Despite the excellent model agreement, both the temperature and unphysically small radius are in disagreement with the values obtained from the evolutionary models, further emphasising a long standing tension for this class of objects.”

My note. HIP 65426 b is 7.1 Mjup and radius 0.92 Rjup. Apparently measurements for giant exoplanets like this conflict with various stellar evolution models in use for the giant exoplanets.

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September 10, 2022 at 2:55 pm

Rod, did they state a temperature based on the relative brightnesses in the various IR channels, something like a correlated color temperature?

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September 11, 2022 at 7:16 am

Martian-Bachelor, I read about HIP 65426 b at

The paper cited is 35-pages,

"HIP 65426 b is clearly detected in all seven of our observational filters, representing the first images of an exoplanet to be obtained by JWST"

The report indicates a variety of filters used to determine the mass and luminosity of the exoplanet.

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