November 2018

Galaxy mergers reveal pairs of supermassive black holes

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An article published in the journal “Nature” describes the discovery of five pairs of supermassive black holes in galaxies in the final stages of mergers. A team of researchers coordinated by the University of Maryland used data gathered at the Keck Observatory in Hawaii and in over twenty years by the Hubbble space telescope to find out these cases among hundreds of galaxies selected from those with strong X-ray emissions detected by the Swift space telescope.

Abell 2597 seen by ALMA (yellow), MUSE (red) and Chandra (blue-purple) (Image ALMA (ESO/NAOJ/NRAO), Tremblay et al.; NRAO/AUI/NSF, B. Saxton; NASA/Chandra; ESO/VLT)

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An article published in “The Astrophysical Journal” describes the observation of a sort of galactic fountain of cold molecular gas pumped by a supermassive black hole in the brightest galaxy of the galaxy cluster Abell 2597. A team of researchers used the ALMA radio telescope and the MUSE spectrograph mounted on ESO’s VLT to observe for the first time a cycle that includes both inflow and outflow that powers that fountain.

The 2MASS J18082002-5104378 system in the rectangle (Image courtesy ESO/Beletsky/DSS1 + DSS2 + 2MASS)

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An article published in “The Astrophysical Journal” describes the discovery of a tiny star whose age was estimated at around 13.5 billion years, making it one of the oldest stars in the universe. A team of astronomers studied the star known only as 2MASS J18082002-5104378 B, whose mass is only 14% of the Sun’s, and in particular its composition discovering the very low metal content. The conclusion is that it’s almost completely formed from materials created after the Big Bang.

Simulation of materials near Sagittarius A* (Image ESO/Gravity Consortium/L. Calçada)

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An article published in the journal “Astronomy & Astrophysics” describes the detection of very hot gas clouds that orbit the supermassive black hole at the center of the Milky Way, called Sagittarius A* or simply SgrA*. A team of researchers used the GRAVITY instrument installed on ESO’s VLT to observe infrared light flares coming from the gas and dust accretion disk that orbits SgrA* at very high speed. These are the most accurate observations of materials so close to a black hole’s event horizon.

The Dawn space probe during its preparation (Photo NASA/Amanda Diller)

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NASA announced the end of the mission of its Dawn space probe after it ran out of the hydrazine used by its thrusters prevented it from orienting towards Earth to communicate with the mission control through NASA’s Deep Space Network. Dawn is in a stable orbit around the dwarf planet Ceres and will probably remain there for at least 50 years. It’s the only space probe to have orbited two celestial bodies since the first part of its mission was orbiting the giant asteroid Vesta.