Brown Dwarf Could Be the First Real Test for Imaging Alien Earths — A New Target for NASA’s Roman Telescope

Brown Dwarf May Give NASA’s Roman Telescope Its First Chance To Demonstrate Earth-Imaging Technology

Astronomers have identified two new companions to nearby stars that could become practical targets for a critical on-orbit test of NASA’s upcoming Nancy Grace Roman Space Telescope. In two recent studies, an international team reports the discovery of a gas giant orbiting HIP 54515 and a brown dwarf orbiting HIP 71618.

Both detections combined fresh planet-imaging observations from Japan’s Subaru Telescope in Hawaii with archival astrometric data from the European Space Agency’s Gaia spacecraft. The brown dwarf in particular appears to have the right separation and contrast relative to its host star to serve as an ideal test target for Roman’s coronagraph, say the researchers.

Why This Matters

When it launches — possibly as soon as next year — Roman will carry a coronagraph designed to suppress a star’s overwhelming glare so much fainter nearby companions can be seen. Roman’s coronagraph is a technical stepping stone toward more advanced starlight-suppression systems planned for the future Habitable Worlds Observatory, currently envisioned for the late 2030s.

To validate those technologies, astronomers must show they can detect objects extremely close to their stars that are roughly 10 million times fainter than their hosts. A brown dwarf is essentially a dim, "failed" star: it emits little visible light but is bright enough at infrared wavelengths to be a realistic, measurable target. Its combination of angular separation and brightness makes the HIP 71618 companion a promising demonstration object for Roman’s coronagraph.

“It’s going to test technologies that we will need to be able to image an Earth,” says Thayne Currie, an astrophysicist at the University of Texas at San Antonio and a co-author on the studies.

Broader Significance

Experts emphasize that these discoveries also reflect important progress in exoplanet science. Direct-imaging techniques — which produce pictures of companions rather than inferring them from a star’s motion or dimming — have matured to the point where they can reveal both giant exoplanets and faint brown dwarfs around nearby stars.

Rebecca Charbonneau, a historian of science at the American Institute of Physics, notes that direct imaging is both a technical milestone and a conceptual shift: it lets scientists study planetary systems more like miniature versions of our own solar system, rather than relying solely on indirect detection methods.

Follow-up observations with Roman and ground-based facilities will refine the companions' properties and confirm whether the HIP 71618 brown dwarf is the practical on-orbit target the community needs to validate future Earth-imaging technologies.