On July 1, 2026, NASA's TESS (Transiting Exoplanet Survey Satellite) discovered a new planet, Gaia23bra b, using gravitational microlensing. This finding highlights the potential for uncovering more hidden planets in TESS's eight years of archived data.
Gaia23bra b: A Unique Discovery
Gaia23bra b is the first microlensing planet found by TESS, orbiting an orange dwarf star approximately 80% the mass of the sun. Unlike TESS's typical transiting planets that cause dimming, Gaia23bra b's presence was revealed through its effect on a more distant background star's light. This phenomenon, known as gravitational microlensing, occurs when the light from a background star is magnified due to the gravitational field of a foreground star and its planet.
According to Diana Dragomir, a professor at the University of New Mexico, "When TESS launched, no one expected it to ever be capable of finding this kind of planet." The discovery suggests that similar microlensing planets may be concealed within TESS's previous observations.
The Process of Gravitational Microlensing
The microlensing event that led to the discovery of Gaia23bra b was first detected in 2023 using the now-retired Gaia space telescope from the European Space Agency. Researchers found that TESS had also captured this event, providing denser time coverage that revealed additional features in the light curve, allowing for the measurement of the planet's mass ratio relative to its host star.
Gaia23bra b has a mass approximately 1.63 times that of Jupiter and orbits at a distance similar to that of Jupiter from the sun. This discovery emphasizes the limitations of the primary transit method, which is more effective for detecting closer-in planets.
Implications for Future Exoplanet Discoveries
The significance of finding Gaia23bra b lies in its implications for future exoplanet research. Microlensing is particularly sensitive to planets that orbit at greater distances from their stars, including those in the habitable zone. Currently, less than 5% of known exoplanets have been discovered through microlensing, indicating that many more may exist.
As Mallory Harris, a UNM Ph.D. candidate and first author of the study, states, "TESS happened to be monitoring the same area of the sky during the event, and its denser time coverage showed extra features in the light curve caused by a planet." This highlights the potential for TESS to uncover additional microlensing events that have yet to be recognized.
- Gaia23bra b is the first microlensing planet found by TESS.
- It orbits an orange dwarf star similar to the sun.
- The planet's mass is about 1.63 times that of Jupiter.
- Microlensing is sensitive to planets at Earth-like distances or farther.
- Less than 5% of known exoplanets have been discovered through microlensing.
🤖 This article was rewritten by Feed and Figures' editorial AI from a report originally published by Phys.org. Facts and quotes are preserved from the original; the rewrite focuses on clarity and structure. For the unedited original, see the source link below.
