TESS survey identifies new planet candidates around faint stars for future UV observations

A new search of faint stars using the TESS mission has identified 262 planet candidates, including 181 that are entirely new. By focusing on stars previously overlooked due to their faintness, this work provides a vital catalog for the upcoming ULTRASAT mission, which will study the atmospheres of these distant worlds by observing their transits in both ultraviolet and visible light.

Star system: TIC 220432308 | Distance from the Sun: 1129 light years

The Transiting Exoplanet Survey Satellite, or TESS, has primarily focused on bright stars to identify planets for follow-up studies. However, many faint stars remain unexplored despite TESS having the necessary sensitivity to detect planets orbiting them. By shifting the focus to these dimmer targets, researchers can significantly increase the total number of known planets available for detailed investigation.

To identify these worlds, the search analyzed light curves—the measurement of a star's brightness over time—specifically optimized for faint stars down to a magnitude of 16 in the fields targeted by the upcoming ULTRASAT telescope. This method allowed for the detection of transit events, where a planet passes in front of its host star and causes a small, temporary dip in the observed light. Researchers then assessed whether these candidates could be observed by ULTRASAT, a space telescope designed for high-cadence ultraviolet surveys.

The findings provide a foundation for future atmospheric studies. By combining data from ultraviolet and optical observations, it is possible to gain insight into the composition and evolution of exoplanet atmospheres, a field that has historically been limited by the lack of ultraviolet-capable instruments. With 113 candidates identified as suitable for ULTRASAT, this work establishes a clear path toward the largest study of its kind.

Key findings
262 planet candidates identified through a survey of faint stars.
181 of the detected planet candidates are newly identified.
2 planet candidates have been statistically validated as planets.
113 candidates are suitable for atmospheric observation with the ULTRASAT telescope.

Scientific study

Two Validated Planets and 179 Candidates From a TESS Faint Star Transit Search in the ULTRASAT Fields (external link)