Astronomy / Astrophysics

Scheme of the the HD 20794 system with its habitable zone in green (Image courtesy Gabriel Pérez (IAC))

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An article published in the journal “Astronomy & Astrophysics” reports the identification of the exoplanet that was cataloged as HD 20794 d. A team of researchers used data collected in more than twenty years with two spectrographs: ESPRESSO, mounted on the VLT, and HARPS, at the La Silla Observatory, both of ESO in Chile, to identify HD 20794 d and define its orbit and characteristics. The analysis indicates that it’s a super-Earth with a mass almost six times the Earth’s with a highly elliptical orbit that brings it into the habitable zone of its star system for part of its year.

A sample from asteroid Bennu (Photo courtesy Yasuhiro Oba)

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Two articles, one published in the journal “Nature” and one in “Nature Astronomy” report the results of examinations of samples from asteroid Bennu with the discovery of the presence of all the DNA and RNA bases and 14 of the 20 amino acids present on Earth. Two teams of researchers analyzed these samples, which were collected by NASA’s OSIRIS-REx space probe, which brought them back to Earth. Building blocks of life were also found in samples from the asteroid Ryugu brought back to Earth by the Hayabusa 2 space probe and the ones found in the samples brought back from Bennu offer new confirmation that the Earth may have been “seeded” by asteroids.

Perseus and Centaurus galaxy clusters

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An article published in the journal Nature Astronomy reports the results of a study of seven galaxy clusters which contain various supermassive black holes that offers evidence that outbursts generated at these black holes help cool the gas they feed on. A team of researchers used observations with multiple instruments to examine seven galaxy clusters. Outbursts in the form of jets from the supermassive black holes in those clusters cool the gas by forming thin filaments. Some of that gas will eventually flow back toward those black holes, triggering more outbursts in a mechanism in which the black holes “cook” their own meals.

Some Martian mounds (Image ESA/ TGO/ CaSSIS)

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An article published in the journal “Nature Geoscience” reports a study on the mounds in Mawrth Vallis, a valley on the planet Mars considered very interesting for the traces of the ancient presence of liquid water. A team of researchers from the Open University and the Natural History Museum in London used data collected by various space probes to perform geomorphological and spectroscopic analyses of the mounds. Their conclusions are that they’re the remains that were formed by erosion by the retreat of the plateau in the Noachian period, between 4.1 and 3.7 billion years ago. For this reason, they believe that they constitute a sort of stratigraphic record of the changes in the presence of water in Mawrth Vallis.

The Andromeda Galaxy

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A new image of the Andromeda Galaxy has been created by combining images captured by the Hubble Space Telescope from about 600 separate fields of view. It took two observing programs over a total of more than a decade and a thousand Hubble orbits to achieve this result. The new mosaic includes more than two hundred million individual stars in the Andromeda Galaxy, a minority made up of the stars that are more massive and bright than the Sun. Hubble’s observations provide a wealth of information about these stars that helps us better understand Andromeda’s history.