Transit-based exoplanet survey finds its first microlensing exoplanet
Additional planetary signals may be hidden in TESS data, say astronomers The post Transit-based exoplanet survey finds its first microlensing exoplanet appeared first on Physics World .
NASA's Transiting Exoplanet Survey Satellite (TESS) has identified its first exoplanet using the microlensing method. This "super Jupiter" named Gaia23bra b was spotted when it and its host star acted as a gravitational lens, amplifying the light from a distant background star. The transit method, which TESS was primarily designed for, detects planets by observing the periodic dimming of a star's light as a planet passes in front of it.
However, this approach only works for planets with orbits nearly edge-on to Earth. Microlensing, on the other hand, can detect planets at a wider range of distances from their stars, including those in the habitable zone. Astronomers first noticed a brightening event in the Gaia23bra system in 2023 through the European Space Agency's Gaia space telescope.
However, Gaia did not recognize it as a binary-star system or detect the planet due to sparse observations. Using TESS's denser and more frequent data, researchers identified additional brightness variations in the light curve, indicating the presence of the planet. The discovered planet is approximately 1.63 times larger than Jupiter and orbits an orange dwarf star about 20% smaller than our Sun.
Microlensing complements the transit method by detecting planets with lower mass and greater orbital distances. However, microlensing events are one-time occurrences, making the Gaia23bra system a unique opportunity for study. Future surveys can potentially identify additional microlensing events in archived TESS data, further expanding the range of planets that can be detected.
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