37 Worlds Between Stars and Planets: SPHEREx Reads Their Atmospheres
brown dwarf
A space object formed like a star, but not massive enough to shine like one.
SPHEREx
NASA's infrared space telescope for studying light across the sky.
spectrum
A pattern made by arranging light measurements by color.
What happened
NASA, the U.S. space agency, announced new results from SPHEREx, an infrared space telescope. The team studied observations of 37 nearby brown dwarfs. Brown dwarfs form when gas clouds collapse, like stars. They are not massive enough to keep hydrogen fusion going in their cores. They can also resemble giant planets. The study appeared in The Astrophysical Journal. NASA's report
How the telescope read them
SPHEREx measures brightness in 102 different colors. The range runs from deep red light to invisible infrared light. Arranged together, those measurements make a spectrum. Molecules leave recognizable absorption patterns in that spectrum. Researchers can use those patterns to infer what surrounds a brown dwarf. The sample covered a wide temperature range, from about 2,200 degrees Celsius to minus 20 degrees Celsius. The telescope also maps the whole sky and produces about 3,600 unique images daily.
What the atmospheres showed
The spectra contained signatures of water, carbon dioxide, carbon monoxide, and methane. The patterns changed from object to object. Some brown dwarfs were in a transition where their thick clouds became thinner. Their atmospheres then became richer in methane. This suggests that cooling changes more than brightness. It also changes the chemistry and cloud structure that observers see.
Why the result matters
Only a few dozen brown dwarfs have been studied closely with space telescopes. Ground telescopes cannot easily see some useful wavelengths. Water in Earth's atmosphere absorbs them. SPHEREx observes from orbit, so it can examine those wavelengths across the sky. Brown dwarfs form like stars, yet their atmospheres can resemble those of giant planets. Studying both sides may improve models of cloudy, cool worlds.
What is confirmed
The measurements show that brown dwarf atmospheres contain several important molecules. They also show that similar temperatures do not guarantee similar spectra. The paper's abstract reports that current models reproduce broad trends. However, they struggle around cloud transitions. They also have trouble matching features linked to carbon monoxide and carbon dioxide. The observed brown dwarfs favored a model with weaker atmospheric mixing, though that preference does not solve every mismatch. The study record
What remains unknown
Scientists still do not know why objects at similar temperatures look so different. The current report does not settle one cause. It points instead to a need for more observations and better models. Questions about cloud changes, chemistry, and the objects' long-term cooling remain open.
What to watch next
SPHEREx researchers are analyzing thousands of additional brown dwarfs. Those data may show whether the patterns from 37 objects hold more broadly. They may also reveal which models work across the full temperature range. NASA says the dataset is freely available to scientists and the public. The next step is a broader comparison of many faint worlds.
SPHEREx Finds 37 Dark Worlds with Rich Atmospheres
📰 Full story: 37 Worlds Between Stars and Planets: SPHEREx Reads Their Atmospheres
NASA, the U.S. space agency, used its SPHEREx space telescope to study 37 nearby brown dwarfs. It found several gases and surprising differences between similar objects.
brown dwarf
A warm space object that is smaller than a star and does not shine like one.
SPHEREx
NASA's space telescope for measuring light across the sky.
spectrum
A pattern made by arranging light by color.
💡 The gist
- NASA, the U.S. space agency, used its SPHEREx space telescope.
- It studied 37 nearby brown dwarfs.
- Their atmospheres contained water, carbon dioxide, carbon monoxide, and methane.
What is a brown dwarf?
A brown dwarf begins like a star. A cloud of gas collapses to make it. But it is not heavy enough to keep a star-making reaction running. It can stay warm inside and glow faintly. Some brown dwarfs move through space without a parent star. Their atmospheres can look more like giant planets.
How did SPHEREx learn this?
SPHEREx studies light across the whole sky. It measures brightness in 102 colors. The colors include deep red light and invisible infrared light. When scientists arrange the measurements, they get a spectrum. The spectrum can show clues from gases around the object. NASA says the 37 objects covered temperatures from about 2,200 degrees Celsius to minus 20 degrees Celsius. This range lets researchers compare warmer and cooler brown dwarfs.
What did it find?
The light carried signs of water, carbon dioxide, carbon monoxide, and methane. The signs changed between objects. Some brown dwarfs showed a change from thick clouds to thinner clouds. Their atmospheres became richer in methane. Yet objects with similar temperatures still had different spectra. Temperature alone does not explain every difference.
Why does that matter?
Scientists have closely studied only a few dozen brown dwarfs with space telescopes. Earth's atmosphere blocks some useful wavelengths. SPHEREx looks from orbit, so it can see more of them. The study also tested computer models of brown dwarf atmospheres. The models captured broad trends. They struggled most when clouds changed. They also struggled with some carbon monoxide and carbon dioxide features.
What comes next?
SPHEREx is analyzing thousands more brown dwarfs. More data may show which differences are common. They may also improve the models. The research record is available here.
A Telescope Looks at Dark Star-Like Worlds
📰 Full story: 37 Worlds Between Stars and Planets: SPHEREx Reads Their Atmospheres
SPHEREx looked at 37 brown dwarfs. Their gases were not all the same.
brown dwarf
A small, warm space world that cannot shine like a star.
SPHEREx
NASA's space telescope for studying light across the sky.
methane
A gas found around some brown dwarfs.
NASA is the U.S. space agency. It runs a space telescope called SPHEREx. SPHEREx looked at 37 small, warm worlds called brown dwarfs. They begin in clouds of gas. They cannot shine as strongly as stars. Some travel without a bigger star nearby. Their atmosphere is the gas around them. SPHEREx used 102 colors of light. Light can show clues about gases. It found water and methane. The brown dwarfs did not all match. Even similar temperatures made different light patterns. Scientists will study many more.