Minerals in space
NASA’s James Webb Space Telescope’s 2024 NIRCam image shows protostar EC 53 circled. Researchers using new data from Webb’s MIRI proved that crystalline silicates form in the hottest part of the disk of gas and dust surrounding the star — and may be shot to the system’s edges.
The outer reaches of our Solar System contains a ring of dwarf planets, planetessimals, and icy boulders which is called the Kuiper Belt, of which Pluto is one of the largest of many constituents. Now we have discovered many solar systems (stellar systems?) around other stars, we can research into analogous exoKuiper belts.
Sometimes those icy boulders can become comets, falling inward towards their host stars, and in our case from the outer Solar System to the Sun. One curious feature of Solar System comets is that they contain minerals that could have been only forged at high temperatures, namely silicates in crystalline form like forsterite (Mg2SiO4) and enstatite (Mg2Si2O6). The outer Solar System (and those exoKuiper belts) are cold places though – for example, the surface temperature of Pluto is on average about 40 degrees about absolute zero, or -225 degrees C. Those pretty crystalline minerals had to come from somewhere else then, but where?
In a new study with the James Webb Space Telescope, a team of astronomers (including our Doug Johnstone) have found a good answer – the minerals are actually formed in the inner regions of the disks from which planets form, the part closest to the young stars, and then are flung out to the outer parts of the disk by the outflows also generated by those disks and young stars, implanting the crystalline silicates far away from their origins. The team figured this out when looking at a very embedded protostar called EC 53 in a relatively nearby patch of dense gas in the constellation Serpens – I’ve attached a nice picture from Webb with a dashed circle identifying EC 53 itself. This protostar was previously known to be variable, in the sense that every 18 months it would brighten up due to a sudden increase in the rate at which it was gobbling up its surrounding disk. That active state would last about 30 days before quieting down again. The team cleverly took Webb data of EC 53 in both its quiescent and active states to see what changes between states.
By using Webb’s Mid-InfraRed Instrument (MIRI), the team split up the mid-infrared light from EC 53 into its component wavelengths and noted the tell-tale signals of forsterite and enstatite only during the time when the disk was in its active accretion phase, when the disk was hotter due to the increased impacts of gas and dust onto the young star’s surface. In their paper, the detection is described as being “the first direct observational evidence for in situ silicate crystallization during an episodic accretion burst.” Further, they also spotted in their Webb data traces of a “nested outflow,” a narrow jet of atomic gas moving at high speed surrounded by a molecular gas moving at slower speed, just the kind of mechanism that would transport the newly formed crystalline silicates outward like water spewing from a fountain. Though the team did not directly see the silicates being transported to the outer part of the disk, no other mechanism for moving the crystalline minerals outward seems plausible at this time.
For more information, here’s a link to the related NASA press release and a link to the team’s paper published 2026 January 21st in Nature.
