Latest astronomy nouvelles

The star HD 158485, used to calibrate the James Webb Space Telescope, has been identified as a binary system. By analyzing light fluctuations from two pulsating stars in the pair, researchers calculated the orbital characteristics of the system. This finding is significant because the presence of an unseen companion star can alter the expected brightness data used for astronomical observations....

Observations of the ultrahot Jupiter KELT-18 b confirm that the planet is losing its atmosphere. By using high-resolution spectroscopy, researchers detected a signature of metastable helium escaping from the planet. This finding highlights the intense photoevaporation occurring on the massive gas giant as it orbits its host star....

Researchers have mapped the three-dimensional atmospheric structure of the hot Jupiter WASP-17 b. By observing the planet as it transits its star, the data reveals a stark 650 Kelvin temperature difference between the planet's morning and evening limbs. These results provide new insights into the complex dynamics and chemical distribution within the atmospheres of giant gas planets orbiting distant stars....

New analysis of the nearby orange dwarf HD 219134 refines its physical dimensions and age. By applying advanced seismic modeling, this study resolves previous disagreements regarding the star's radius and offers a clearer look at how high-energy radiation has shaped the atmospheres of its orbiting planets over nearly nine billion years....

Recent observations of the hot Jupiter WASP-39 b show distinct differences between its morning and evening atmospheric limbs. By comparing five different climate models with data from the JWST telescope, researchers analyzed how clouds, chemical processes, and temperature variations contribute to these observed asymmetries, though current models still struggle to fully replicate the measured carbon dioxide signal....

Researchers have conducted the first high-resolution atmospheric study of the hot gas giant WASP-13 b. By observing four transits, the team refined the orbital geometry of this inflated planet and searched for chemical signatures in its atmosphere. While the study did not detect distinct molecular absorption, it provides important evidence that high-altitude clouds likely obscure the planet's atmospheric features....

Researchers have identified a new protoplanet candidate, EK Chamaeleontis b (EK Cha b), orbiting a young red dwarf star known as EK Cha. This discovery, made using data from multiple high-resolution telescopes, reveals key signs of an object still in its formative stages, including its own potential disk of gas and dust. This finding helps bridge a gap in our knowledge of how giant planets form around smaller, cool stars....

Researchers have identified gaseous silicon monoxide and silicate clouds in the atmospheres of three benchmark early L-dwarf companions, HD 89744 B, Gliese 1048 B, and LSPM J0632+5053 B. By analyzing data from the James Webb Space Telescope, the team tracked how silicon transitions from a gas into mineral grains to form clouds, providing a clearer picture of atmospheric processes in these cool, star-like objects....

Researchers have analyzed the atmosphere of the extreme exoplanet LTT 9779 b, an ultrahot Neptune. By using high-resolution spectroscopy, they identified water vapor on the planet's dayside and found no signs of strong atmospheric escape. The data suggest the planet does not have a thermal inversion, meaning its temperature decreases normally with altitude, and align with expectations of a tidally locked world....