JWST observes the Kuiper Belt: Sedna, Gonggong, and Quaoar

The Kuiper Belt, the huge area on the fringe of our solar system populated by numerous icy objects, is a treasure trove of scientific discoveries. The detection and characterization of Kuiper Belt Objects (KBOs), typically known as Trans-Neptunian Objects (TNOs), has led to a brand new understanding of the historical past of the solar system.

The disposition of KBOs is an indicator of gravitational currents which have formed the solar system and reveal a dynamic historical past of planetary migrations. For the reason that late twentieth century, scientists have been wanting to get a better take a look at KBOs to study extra about their orbits and composition.

Finding out our bodies within the outer solar system is without doubt one of the many targets of the James Webb Area Telescope (JWST). Utilizing information obtained by Webb’s Close to-Infrared Spectrometer (NIRSpec), a global group of astronomers noticed three dwarf planets within the Kuiper Belt: Sedna, Gonggong, and Quaoar. These observations revealed a number of attention-grabbing issues about their respective orbits and composition, together with gentle hydrocarbons and sophisticated natural molecules believed to be the product of methane irradiation.

The analysis was led by Joshua Emery, an Affiliate Professor of Astronomy and Planetary Sciences at Northern Arizona College. He was joined by researchers from NASA’s Goddard Area Flight Heart (GSFC), the Institut d’Astrophysique Spatiale (Université Paris-Saclay), the Pinhead Institute, the Florida Area Institute (College of Central Florida), the Lowell Observatory, the Southwest Analysis Institute (SwRI), the Area Telescope Science Institute (STScI), American College. and Cornell College. A preprint of their paper has been posted to the arXiv server and is being reviewed for publication by Icarus.

Regardless of all the advances in astronomy and robotic explorers, what we all know concerning the Trans-Neptunian Area and the Kuiper Belt continues to be restricted. Thus far, the one mission to review Uranus, Neptune, and their main satellites was the Voyager 2 mission, which flew previous these ice giants in 1986 and 1989, respectively. Furthermore, the New Horizons mission was the primary spacecraft to review Pluto and its satellites (in July 2015) and the one one to come across an object within the Kuiper Belt, which occurred on January 1st, 2019, when it flew previous the KBO referred to as Arrokoth.

This is without doubt one of the many explanation why astronomers have eagerly awaited the launch of the JWST. Along with finding out exoplanets and the earliest galaxies within the universe, its highly effective infrared imaging capabilities have additionally been turned towards our yard, revealing new pictures of Mars, Jupiter, and its largest satellites. For his or her research, Emery and his colleagues consulted near-infrared information obtained by Webb of three planetoids within the Kuiper Belt—Sedna, Gonggong, and Quaoar. These our bodies are about 1,000 km (620 mi) in diameter, which locations them inside the IAU designation for Dwarf Planets.

As Emery informed Universe As we speak by way of e mail, these our bodies are particularly attention-grabbing to astronomers due to their dimension, orbits, and compositions. Different Trans-Neptunian our bodies—like Pluto, Eris, Haumea, and Makemake—have all retained risky ices on their surfaces (nitrogen, methane, and so forth.). The one exception is Haumea, which misplaced its volatiles in a big affect (apparently). As Emery mentioned, they wished to see if Sedna, Gonggong, and Quaoar have comparable volatiles on their surfaces as nicely:

“Earlier work has proven that they are able to. Whereas all being roughly comparable sizes, their orbits are distinct. Sedna is an inside Oort Cloud object with perihelion of 76 AU and aphelion of practically 1,000 AU, Gonggong is in a really elliptical orbit additionally, with perihelion of 33 AU and aphelion ~100 AU, and Quaoar is in a comparatively round orbit close to 43 AU. These orbits place the our bodies in numerous temperature regimes and completely different, irradiation environments (Sedna, for example, spends most of its time outdoors the sun’s heliosphere). We wished to analyze how these completely different orbits might have an effect on the surfaces. There are additionally different attention-grabbing ices and sophisticated organics on the surfaces.”

Utilizing information from Webb’s NIRSpec instrument, the group noticed all three our bodies in low-resolution prism mode at wavelengths spanning 0.7 to five.2 micrometers (µm)—inserting all of them within the near-infrared spectrum. Further observations have been product of Quaoar from 0.97 to three.16 µm utilizing medium-resolution gratings at ten instances the spectral decision. The ensuing spectra revealed some attention-grabbing issues about these TNOs and the floor compositions, mentioned Emery:

“We discovered ample ethane (C₂H₆) on all three our bodies, most prominently on Sedna. Sedna additionally exhibits acetylene (C₂H₂) and ethylene (C₂H₄). The abundances correlate with the orbit (most on Sedna, much less on Gonggong, least on Quaoar), which is in keeping with relative temperatures and irradiation environments. These molecules are direct irradiation merchandise of methane (CH₄). If ethane (or the others) had been on the surfaces for a very long time, they’d have been transformed to much more advanced molecules by irradiation. Since we nonetheless see them, we suspect that methane (CH₄) should be resupplied to the surfaces pretty frequently.”

These findings are in keeping with these offered in a pair of latest research led by Dr. Will Grundy, an astronomer with the Lowell Observatory and a co-investigator on NASA’s New Horizons mission, and Chris Glein, a planetary scientist and geochemist on the SwRI. For each research, Grundy, Glien, and their colleagues measured deuterium/hydrogen (D/H) ratios in methane on Eris and Makemake and concluded that the methane was not primordial. As a substitute, they argue that the ratios outcome from methane being processed of their interiors and delivered to the floor.

“We propose the identical could also be true for Sedna, Gonggong, and Quaoar,” mentioned Emery. “We additionally see that the spectra of Sedna, Gonggong, and Quaoar are distinct from these of smaller KBOs. There have been talks at two latest conferences that confirmed JWST information of smaller KBOs cluster into three teams, none of which appear to be Sedna, Gonggong, and Quaoar. That result’s in keeping with our three bigger our bodies having a unique geothermal historical past.”

These findings might have vital implications for the research of KBOs, TNOs, and different objects within the outer solar system. This contains new perception into the formation of objects past the Frost Line in planetary methods, which refers back to the line past which risky compounds will freeze strong. In our solar system, the Trans-Neptunian area corresponds to the nitrogen line, the place our bodies will retain massive quantities of volatiles with very low freezing factors (i.e., nitrogen, methane, and ammonia).

These findings, mentioned Emery, additionally reveal what kind of evolutionary processes are at work for our bodies on this area. “The first implication could also be discovering the scale at which KBOs have turn into heat sufficient for inside reprocessing of primordial ices, even perhaps differentiation. We must also be capable of use these spectra to raised perceive irradiation processing of floor ices within the outer solar system. And future research will even be capable of look in additional element at risky stability and the likelihood for atmospheres on these our bodies over any elements of their orbits.”

This research’s outcomes additionally showcase the talents of the JWST, which has confirmed its value many instances because it turned operational early final yr. Additionally they remind us that along with enabling new visions and breakthroughs of distant planets, galaxies, and the large-scale construction of the universe, Webb may also reveal issues about our little nook of the cosmos.

“The JWST information are implausible,” added Emery. “They enabled us to get spectra at longer wavelengths than we will from the bottom, which enabled the detection of those ices. Typically, when observing in a brand new wavelength vary, the preliminary information may be fairly poor high quality. JWST not solely opened up a brand new wavelength vary but in addition supplied fantastically high-quality information which are delicate to a collection of supplies on the surfaces within the outer solar system.”