Blog about planets.

Artist's illustration of the exoplanet Tahay / GJ 367 b (Image NASA)

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.

The HIP 81208 system seen by SPHERE

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.

Artist's concept of the exoplanet K2-18 b with its star in the background (Image NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University))

An article accepted for publication in the journal “The Astrophysical Journal Letters” reports the results of a study of the exoplanet K2-18 b, including the discovery of carbon compounds such as methane in its atmosphere. A team of researchers led by Nikku Madhusudhan of the British University of Cambridge used observations conducted with the James Webb Space Telescope’s NIRISS and NIRSpec instruments to probe the atmosphere of K2-18 b. It’s an exoplanet already considered interesting due to its characteristics and its position in its planetary system’s habitable zone. Spectral analyzes also suggest the possible presence of dimethyl sulfide (DMS), a compound considered a biomarker. These are discoveries that add to the previous ones regarding an exoplanet that led to the proposal of the Hycean class.

Artist's concept of the TOI-4600 system (Image courtesy Tedi Vick)

An article published in the “Astrophysical Journal Letters” reports the discovery of two exoplanets orbiting the star TOI-4600 of which the outermost is the one with the longest year discovered so far. A team of researchers used observations conducted with NASA’s TESS space telescope to find traces of these two gas exoplanets. Other ground-based observatories were used to confirm the existence of these two exoplanets and obtain more information about them. TOI-4600 b has a year of nearly 83 Earth days, a bit shorter than Mercury’s, while TOI-4600 c has a year of nearly 483 days, the longest of all known exoplanets. This is a useful discovery to understand what other planetary systems are like because exoplanets close to their stars are much easier to discover while we still know very little about the ones far from their stars.

Artist's concept of the HD 45166 system with the helium star in the foreground (Image ESO/L. Calçada)

An article published in the journal “Science” reports a study that identifies one of the stars in the binary system HD 45166 as the likely precursor of a magnetar. A team of researchers led by Tomer Shenar of the University of Amsterdam used various telescopes to study a so-called helium star, a massive star that is nearing the end of its life and has already ejected its outer layers and is left with a core formed by helium on its surface. This star revealed an extremely powerful magnetic field, estimated to be about 100,000 times the Earth’s.