Unlike the close-in transiting planets that TESS typically discovers, the newly identified planet is a super-Jupiter that orbits far from its host star once every 180 days, according to a team from Queen’s University Belfast.
The planet, named Gaia23bra b, has a mass about 1.6 times that of Jupiter. Planets of this size and mass are commonly referred to as super-Jupiters. It is also an exoplanet, the term used for any planet located outside our solar system.
Describing the findings, Diana Dragomir, a professor at the University of New Mexico in Albuquerque and co-author of the study, said that when TESS was launched, no one expected it to be capable of discovering this type of planet.
She added, “At 1.6 times Jupiter’s mass and a similar orbital distance, it would be extremely unlikely to find such a planet via the primary detection method TESS was designed for. The discovery implies that there are probably other so-called microlensing planets hiding in TESS’s data that we hadn’t previously thought to look for.”
Astronomers first detected signs of Gaia23bra b in 2023 using the European Space Agency’s now-retired Gaia space telescope. Gaia’s alert system identified a star that suddenly brightened, an effect that can occur when a foreground star passes in front of a more distant star and magnifies its light through gravitational microlensing.
Researchers later examined archived TESS data and found that the spacecraft had recorded the same event.
The team’s analysis, published on July 1 in The Astrophysical Journal Letters, revealed that Gaia23bra b orbits an orange dwarf star with about 80% of the Sun’s mass. The planet is located nearly 40,000 light-years from Earth, far beyond TESS’s typical search range of around 150 light-years.
