June 2020

The symbiotic nova V407 Cygni seen by EVN

An article published in the journal “Astronomy & Astrophysics” reports a study of V407 Cygni, the first known gamma-ray nova, discovered in 2010. A team of researchers led by Marcello Giroletti from the Italian National Institute of Astrophysics used data collected using the European VLBI Network (EVN) over 16 different periods to monitor the radio emissions of what is a symbiotic nova. The result was the discovery of shock waves generated by the explosion of materials accumulated on the white dwarf’s surface that forms a couple with a red giant from which it steals them.

Artist's concept of Pōniuāʻena (Image courtesy International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld)

An article accepted for publication in “The Astrophysical Journal Letters” reports the discovery of a very bright primordial quasar that was cataloged as J100758.264+211529.207, or simply J1007+2115, and named Pōniuāʻena. A team of researchers used three Mount Maunakea Observatories in Hawaii to identify one of the oldest known quasars, surpassed in age only by the one cataloged as J1342+0928, whose discovery was announced in December 2017.

From Earth we see Pōniuāʻena as it was about 13 billion years ago, a quasar powered by a supermassive black hole with an estimated mass of 1.5 billion times that of the Sun, almost twice the one that powers J1342+0928. This raises more than ever the problem of the quick growth of some primordial supermassive black holes.

HBC 672 seen by Hubble (Image NASA, ESA, and STScI)

An article published in “The Astrophysical Journal” reports multi-epoch observations conducted with the Hubble Space Telescope of the star HBC 672 and the movement of the shadow projected by its protoplanetary disk onto an interstellar cloud. A team of researchers led by Klaus Pontoppidan of the Space Telescope Science Institute (STScI) compared the positions of the shadow over 13 months, noting its movement, which has a visual effect similar to a flapping of wings as its shape reminds of that to the point that the star and its protoplanetary disk have been nicknamed Bat Shadow. It could be a planet that is forming and warping the disk.

Artist's concept of the GW190814 event

An article published in “The Astrophysical Journal Letters” reports a study on the origin of gravitational waves detected in the event cataloged as GW190814 on August 14, 2019, in which a black hole with a mass about 23 times the Sun’s merged with an object with a mass about 2.6 times the Sun’s whose nature is uncertain. The scientists of the LIGO and Virgo collaborations analyzed the data collected by the network of interferometers that recorded the gravitational waves emitted by that event. The problem is that the mass of the less massive object is within a gap where it’s not currently possible to say whether a compact object is a neutron star or a black hole.

Artist's concept of two supermassive black holes in a galaxy

An article published in “The Astrophysical Journal” reports a study of over 2,000 active galactic nuclei (AGN) among which some may have two supermassive black holes. A team of researchers led by Pablo Peñil, a Ph.D. student at Universidad Complutense de Madrid in Spain, analyzed the data collected in nine years of observations from NASA’s Fermi space telescope to identify gamma-ray emissions that repeat every two years and could indicate the interaction of two supermassive black holes. 11 of the galaxies examined have nuclei with this type of emissions while 13 others show hints of that type of emissions and require follow-up observations to verify their nature.