Astronomers from the Harvard-Smithsonian Center for Astrophysics (CfA) and elsewhere report the discovery of a new “hot Jupiter” exoplanet orbiting a rapidly rotating F-type star. The new alien world, designated TOI-4641 b, could be nearly four times more massive than Jupiter. The discovery was detailed in a paper published Dec. 7 on the preprint server. arXiv.
In general, hot Jupiters are gas giant planets with orbital periods between 10 and 200 days. This makes them difficult targets for transit detection and radial velocity tracking studies, compared to their shorter-orbit counterparts known as hot Jupiters.
Now a group of astronomers led by CfA’s Allyson Bieryla has discovered a new such exoplanet. Using NASA’s Transiting Exoplanet Survey Satellite (TESS), which surveys the sky for transiting extrasolar worlds, they identified a transit signal in the light curve of TOI-4641, a star F bright and rapidly rotating (with a projected trajectory). rotation speed of approximately 86.3 km/s). The planetary nature of this signal was confirmed by follow-up photometric and spectroscopic observations.
“A candidate exoplanet orbiting TOI-4641 with a period of 22.1 days was identified in light curves including sector 43 data in the SPOC and QLP pipelines,” the researchers wrote in the paper.
The new planet has a radius of approximately 0.73 Jupiter radii and its maximum mass has been calculated to be 3.87 Jupiter masses. Observations indicate that TOI-4641 b orbits its host star every 22.09 days in a well-aligned orbit, at a distance of approximately 0.173 AU from it. TOI-4641 b is therefore one of the longest-period planets to be carefully characterized, which orbits a hot, rapidly rotating star.
The parent star TOI-4641 (also known as TIC 436873727), located about 286 light years away, has a radius of about 1.72 solar radii and is about 41% more massive than the sun. The star is estimated to be 2.69 billion years old, has a metallicity of -0.09, and its effective temperature was found to be 6,560 K.
The paper’s authors pointed out that long-period exoplanets like TOI-4641 b could be crucial for testing the mechanisms that induce primordial misalignment in planetary systems, given that at such orbital distances, tidal interactions star-planet are assumed to be too weak to be modified. orbital obliquity.
“Testing these predictions motivates the full characterization of planets in long-period orbits around early-type stars,” the scientists concluded.
In total, Bieryla’s team proposes a few mechanisms causing such misalignment, including chaotic accretion, magnetic deformation or changes in the rotation axes of early-type stars, as well as stellar or planetary companions. during the primordial training phase.
