Latest astronomy nouvelles

Its high eccentricity may be the result of past violent scattering events ...

Gas giant Kepler-1658 b is slowly spiraling inward due to tidal interactions with its host star. The observed rate of orbital decay cannot be explained by tidal dissipation in the star alone, but it can be explained if the planet rotates non-synchronously...

Researchers have used ground-based photometry and spectra to study the unocculted starspots on the young star AU Mic. They find that AU Mic has at least two spectral components: a 4000 K ambient photosphere and cool spots that have a temperature of 3000 K and cover 39% of the surface. They also detect a third flux component, which they attribute to flare flux. This study will help us better understand the starspot coverage on AU Mic and other sta...

HD 34700 is a young binary system with a complex protoplanetary disk. A new study has discovered an inner ring in the disk, as well as extended logarithmic spiral arms and misaligned gas rotation patterns. These features suggest that the disk is being shaped by one or more physical mechanisms, such as the presence of an undetected planet or interaction with the surroundings. Further observations are needed to confirm these scenarios....

The TOI-5398 system is a young (650 Myr old) and compact multi-planet system with a hot sub-Neptune orbiting interior to a short-period Saturn planet. The radius and mass of both planets have been measured, constraining their bulk composition....

A new analysis of LHS 1140 b and c, two temperate exoplanets orbiting a nearby star, reveals that LHS 1140 b is likely a mini-Neptune with a thin H/He envelope or a water world. LHS 1140 c remains consistent with a rocky planet, but there is a discrepancy in the transit depths measured by Spitzer and TESS. The candidate LHS 1140 d is not detected, and is attributed to stellar activity....

Two new sub-Neptunes, TOI-904 b and c, have been discovered orbiting the early M dwarf TOI-904. The outer planet, TOI-904 c, is the longest-period M dwarf exoplanet found by TESS, with period 84 days and an estimated equilibrium temperature of 217 K. Future mass measurements and transmission spectroscopy of the similar-sized planets in this system could determine whether they are also similar in density and composition, suggesting a common format...

The two planets in the HD 152843 system have nearly equal masses but differing radii, and the outer planet HD 152843 c has the longest orbital period of any known low-density exoplanet. HD 152843 c is also located in the Saturn valley, the observed lack of planets larger than Neptune but smaller than Saturn. The orbital periods of the planets suggest they are near a 5:3 mean motion resonance, and the brightness of the host star and the low densit...

A temperate, highly eccentric sub-Saturn has been discovered orbiting the bright K-dwarf TOI-2134, in addition to an inner mini-Neptune that was discovered three years ago. The outer planet has a radius of 7.27 R⊕ and a mass of 41.86 M⊕, and a high eccentricity of 0.67, positioning it in the habitable zone of its system for part of its orbit. Further observations are needed to fully constrain the orbit of the outer planet and to study the spin-or...