Six Jupiter-sized worlds may be seen in images captured by the Webb space telescope of NGC1333, a stellar "nursery" full of young celestial objects.
In the young star cluster NGC1333, located about 1,000 light-years from Earth in the constellation Perseus, a team of astronomers found hundreds of newly formed starlike objects, including six infant worlds with masses between five and 15 times that of Jupiter. The dusty disk around the smallest world is exactly like the kind that circle baby stars and give rise to planetary systems. This dusty disk might one day turn into a pack of orbiting moons, says Adam Langeveld, an astrophysicist at Johns Hopkins University.
The discovery is reported in The JWST/NIRISS Deep Spectroscopic Survey for Young Brown Dwarfs and Free-Floating Planets [arxiv]
Here we report results from an extremely deep spectroscopic survey of the young star cluster NGC1333 using NIRISS WFSS on the James Webb Space Telescope. The survey is photometrically complete to K ∼ 21, and includes useful spectra for objects as faint as K ∼ 20.5. The observations cover 19 known brown dwarfs, for most of which we confirm spectral types using NIRISS spectra. We discover six new candidates with L-dwarf spectral types that are plausible planetary-mass members of NGC1333, with estimated masses between 5–15 MJup. One, at ∼ 5 MJup, shows clear infrared excess emission and is a good candidate to be the lowest mass object known to have a disk. We do not find any objects later than mid-L spectral type (M ≲ 4 MJup). The paucity of Jupiter-mass objects, despite the survey's unprecedented sensitivity, suggests that our observations reach the lowest mass objects formed like stars in NGC1333. Our findings put the fraction of FFPMOs in NGC1333 at ∼ 10 % of the number of cluster members, significantly more than expected from the typical log-normal stellar mass function. We also search for wide binaries in our images and report a young brown dwarf with a planetary-mass companion.
The new space telescope is outperforming expectations when it comes to glimpsing smaller exoplanets as well as the baby Jupiters.
One of the smaller planets that JWST looked at is GJ 1214b, which has frustrated astronomers since its discovery in 2009 (SN: 12/16/09). The planet is a sub-Neptune, meaning its size is somewhere between that of a rocky world like Earth and a gaseous one like Neptune. "What the heck are sub-Neptunes?" asked astronomer Eliza Kempton of the University of Maryland in College Park. They could be balls of rock with thick hydrogen and helium atmospheres, or maybe water worlds (SN: 2/22/12). "What we'd like to do with atmospheric characterization is measure their atmospheres and see which is which," Kempton said.
