Astronomers have identified an exoplanet that completes an orbit around its star in less than a day, a remarkable reminder of how diverse planetary systems can be. A recent preprint on arxiv.org presents the findings, detailing the discovery and the methods used to confirm the planet’s existence. The work adds to a growing catalog of ultra-short-period worlds, objects that challenge our understanding of planet formation and migration in tight stellar environments. In explaining the discovery, researchers emphasize the role of transit observations and the precision timing required to discriminate a true planetary signal from stellar noise, a process that has become a hallmark of modern exoplanet science. Attribution: arXiv preprint repository
The Transiting Exoplanet Survey Satellite (TESS) plays a central role in these discoveries. TESS is designed to monitor bright, nearby stars for the tiny dips in brightness caused by transiting planets. Rather than imaging planets directly, TESS detects the slight dimming of starlight as a planet passes in front of its host star. The method relies on continuous, high-precision light curves collected over months of observation, enabling astronomers to infer the presence of a planet from periodic reductions in luminosity. When such a periodic signal is confirmed, it typically signifies the discovery of a transiting world and triggers follow-up observations with ground-based facilities to refine parameters such as size, orbit, and mass. This approach has become a standard in exoplanetary science, providing a scalable pathway to survey thousands of stars across the sky. Attribution: NASA exoplanet program
In a separate but related study, Felipe Murgas and colleagues from the University of La Laguna in Spain have identified another planet that shares characteristics with the broader family of ultra-short-period worlds. This object orbits a star in the HD 20329 system, located about 207 light-years from the Sun. The host star has roughly 0.9 solar masses and mirrors the Sun’s spectral class, placing it among the yet well-studied solar-type stars that harbor tight, short-period planets. The planet HD 20329 b exhibits a radius nearly 1.72 times that of Earth and a mass estimated at roughly 7.42 Earth masses, implying a high density that informs its composition and internal structure. Its orbital period is approximately 22.2 hours, placing it exceptionally close to its star. The planet balances a mere handful of million kilometers from its sun, with a star-planet separation about 0.018 times the Earth-Sun distance. The average surface temperature on HD 20329 b is inferred to be around 2000 Kelvin, a scorching environment that dwarfs the conditions found on Venus or Mercury. Taken together, these measurements confirm HD 20329 b as an ultra-short-period planet, a category that currently includes around 120 known members. Subsequent observations will refine mass and composition estimates and help reveal how such planets can form and survive in intense stellar radiation fields. Attribution: peer-reviewed studies and planetary databases