An article published in “The Astrophysical Journal Letters” reports a study on the exoplanet GJ 367 b, or Gliese 367 b, formally known by the name Tahay, which concludes that its core is composed almost entirely of iron for a density that is almost twice the Earth’s. The researchers also announced the discovery of two more planets in the system of the star GJ 367, formally known as Añañuca, which may be super-Earths.
Just over 30 light-years from Earth, Añañuca is a red dwarf with a mass and size just under half of the Sun’s. Observations began in 2019 with NASA’s TESS space telescope and in 2021 the data collected led to the exploration of the possibility that a planet orbited very close to this star, subsequently confirmed with other instruments. Tahay’s roughly 7.7-hour year is the shortest in the cosmic neighborhood, one reason for interest and worthy of its own name.
A little while ago, the samples taken from the asteroid Bennu brought back to Earth by NASA’s OSIRIS-REx space probe were collected by the American space agency’s crew in the area of their landing, at the Utah Test and Training Range. They will be transported to the Johnson Space Center, the first stage of a series of operations needed to process them while avoiding their contamination. In this study, NASA is collaborating with the Japanese space agency JAXA, which will receive some of the samples to compare them with those collected by its own Hayabusa 2 space probe on the asteroid Ryugu and returned to Earth in December 2020.
An image captured by the Hubble Space Telescope shows Arp 107, a pair of interacting galaxies heading towards a collision. The two galaxies, the spiral galaxy UGC 5984 (or PGC 32620) and the elliptical galaxy MCG +05-26-025 (or PGC 32628), will finish this process in a merger. UGC 5984 is a Seyfert galaxy, a class characterized by an active galactic nucleus that doesn’t block the view of the rest of the galaxy and spectral lines that show a strong ionization. The pair represents an interesting case of the early phase of a galaxy merger.
An article published in the journal “Astronomy & Astrophysics” reports the discovery of an object that could be a gas giant planet or a brown dwarf in the HIP 81208 system. A team of researchers analyzed data from the archive of the observations conducted with the SPHERE instrument mounted on the VLT in Chile discovering an object that was cataloged as HIP 81208 Cb orbiting the smaller of the two stars in this binary system. A brown dwarf was discovered around the more massive star together with the smaller and more distant star in an analysis also published some time ago in an article in “Astronomy & Astrophysics”. The new discovery makes HIP 81208 a so-called hierarchical quadruple system, the first of its kind discovered using a direct imaging system.
An article accepted for publication in “The Astrophysical Journal” reports the results of calculating the universe’s expansion rate based on the observation of Cepheids with the James Webb Space Telescope. In particular, a team of researchers led by Adam Riess used the NIRCam instrument to observe over 330 cepheids in the galaxies NGC 4258 and NGC 5584. The results are more precise than those obtained in the past with the Hubble Space Telescope but confirm the accuracy of the previous calculation of the universe’s expansion rate. This leaves open the question of the difference in results obtained with different methods.