Artist’s impression of a planetesimal (Image courtesy Ko Arimatsu / NAOJ. All rights reserved)

An article published in the journal “Nature Astronomy” reports the discovery of a planetesimal, which is an object of the type that probably formed planets, dwarf planets and asteroids, with an estimated radius of about 1.3 kilometers in the Kuiper Belt. A team led by Ko Arimatsu of the National Astronomical Observatory of Japan (NAOJ) used two 28 cm amateur telescopes using the occultation technique in a 60-hour monitoring. The analysis of the data revealed what appears to be a planetesimal whose presence has long been predicted by the models of planetary formation but had never been identified.

A measurement of the Hubble constant based on quasars suggests possible changes to cosmological models

An article published in the journal “Nature Astronomy” describes the use of quasars as cosmic tracers to measure the expansion of the universe up to 12 billion years ago. Guido Risaliti of the University of Florence and Elisabeta Lusso of Durham University studied the X-ray and optical emissions of a number of quasars using the comparison between those emissions to accurately assess their distances. The results could explain the discrepancies between the different measurements carried out with other methods suggesting that the density of the mysterious dark energy isn’t constant over time.

An explanation to the mystery of the stars surrounded by iron dust

An article published in the journal “The Astophysical Journal Letters” reports the study of stars surrounded by iron dust in the Large Magellanic Cloud, one of the Milky Way’s satellite dwarf galaxies. A team of researchers led by Ester Marini, a doctoral student of the “Roma Tre” University, Rome, Italy, used data collected by NASA’s Spitzer Space Telescope to examine these stars that are in a phase of their life in which they lose their outer layers. Normally, that type of stars is surrounded by silicates and the anomaly is interesting because the dusts are important in the formation of new stars and planets as well.

The planetary nebula ESO 577-24 seen in all its beauty by the Very Large Telescope

ESO has published a new image of the planetary nebula ESO 577-24 captured by its Very Large Telescope (VLT) in Chile thanks to its FORS2 instrument, which for almost twenty years has been capturing some of the best astronomical images obtained by the VLT. ESO 577-24 represents the final phase of the life of the star at its center, cataloged as Abell 36, in astronomical terms an instant of agony since its duration is estimated around 10,000 Earth years.

A rare hypernova shows the possible death of a very massive star

An article published in the journal “Nature” reports the observation of a gamma-ray burst (GRB) cataloged as GRB 171205A associated with a supernova cataloged as SN 2017iuk that was tens of times brighter than that type of event generally is, so as to fall into the category of hypernovae. A team of astronomers led by Luca Izzo of the Instituto de Astrofísica de Andalucía (IAA-CSIC) detected for the first time interaction between the jet that caused the GRB and the outer layers of the exploded star. This allowed to better understand the mechanisms that combine hypernovae and gamma-ray bursts, connected to a “hot cocoon”.