On the run
On the run
Near us, astronomically speaking, we have a young star called AU Microscopii (AU Mic). Located 32 light years away, it is surrounded by a disk of debris created as a result of the collision of asteroids that have been pulverized by the violence of the impacts. It is important to study these areas because it gives us clues about the formation of planets.Image 1: Map of the southern constellation of the Microscope. The image shows most of the stars visible to the naked eye on a clear night. AU Mic is too weak to be able to see it without a small telescope, but its position is marked with a red circle. Credits: ESO / IAU / Sky & Telescope.Astronomers have searched this disk for any lumpy, deformed or especially dense area that suggests the formation or location of possible planets. For this they have used the instrument SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch instrument) installed in the VLT (Very Large Telescope) of ESO in Chile, but what they found was unexpected."SPHERE's images show something totally different from what had been observed before," Anthony Boccaletti explains. Observatory of Paris (France) and main author of the scientific article that exposes the investigation. What Boccaletti and his team observed were five wave arcs at different distances from AU Mic, remembering their appearance to waves in the water.And yet they moveAfter detecting this phenomenon the team resorted to previous images of the disc taken in 2010 and 2011 by the Hubble Space Telescope (NASA / ESA), to see if these waves were also visible. And ... surprise! They identified them, but they also discovered that they had moved: the waves moved, and very fast!Image 2: The upper row shows an image of the AU Mic disk obtained by the Hubble Space Telescope in 2010; the central, a Hubble image of 2011; and the lower one, SPHERE data for 2014. The central black circles show where the light of the central star has been blocked in order to see the disk. The position of the star is indicated schematically. Credits: ESO / NASA / ESA."We reprocessed images of the Hubble data and in the end we obtained enough information to follow the movement of this strange phenomenon over a period of four years," Christian Thalmann explains. ETH Zurich (Switzerland) and member of the team that has carried out the investigation. "By doing this, we discover that the arcs are moving away from the star at speeds of up to 40,000 kilometers per hour," he adds.After analyzing the data, they deduced that the waves furthest away from the star are those that move faster. In fact, three of them could be escaping the gravitational pull of the star. Now they try to find out why this is due, but the fact of seeing the singing disc complicates the interpretation of its three-dimensional structure.Any ideas?"Since none of this has been observed or theoretically predicted before, we can only hypothesize," says Carol Grady, of Eureka Scientific (United States) and member of the investigation. Therefore, the team can not say with certainty what caused these waves around the star, although there are already promising ideas:"An explanation for the strange structure relates to the star's flares, perhaps one of them could have fired something on one of the possible planets, like a violent extraction of material that could now be propagating through the disk," Glenn explains. Schneider, del Steward Observatory (United States) and co-author of the article.Image 3: Sky surrounding the AU Microscopii star, which appears just below the center of the image as an orange star of moderate brightness. Since the photographs are made with filters of different colors and were taken many years ago, AU Mic appears double, since the own movement of the star has caused it to move slightly through the sky during the elapsed time. Credits: ESO / Digitized Sky Survey 2.Following this finding, the team plans to continue observing the AU Mic system with SPHERE, but this time supported by other facilities, including ALMA (Atacama Large Millimeter / submillimeter Array), with the aim of seeing what is happening, because now, they are an unsolved mystery.If you like protoplanetary discs that make races, Do not forget to vote for me Awards Logbooks 2015!This research has been presented in the journal Nature under the title "Fast-Moving Structures in the Debris Disk Around AU Microscopii", by A. Boccaletti et al.The team that has carried out the research consists of Anthony Boccaletti (Observatoire de Paris / CNRS, France), Christian Thalmann (ETH Zürich, Switzerland), Anne-Marie Lagrange (Université Grenoble Alpes, France, CNRS / IPAG, France) , Markus Janson (Stockholm University, Sweden, Max-Planck-Institut für Astronomie, Germany), Jean-Charles Augereau (Université Grenoble Alpes, France, CNRS / IPAG, France), Glenn Schneider (University of Arizona Tucson, United States), Julien Milli (ESO, Chile; CNRS / IPAG, France), Carol Grady (Eureka Scientific, United States), John Debes (STScI, United States), Maud Langlois (CNRS / ENS-L, France), David Mouillet (Université Grenoble Alpes, France, CNRS / IPAG, France), Thomas Henning (Max-Planck-Institut für Astronomie, Germany), Carsten Dominik (University of Amsterdam, The Netherlands), Anne-Lise Maire (INAF-Osservatorio Astronomico di Padova, Italy) , Jean-Luc Beuzit (Université Grenoble Alpes, France, CNRS / IPAG, France), Joe Car are (College of Charleston, United States), Kjetil Dohlen (CNRS / LAM, France), Markus Feldt (Max-Planck-Institut für Astronomie, Germany), Thierry Fusco (ONERA, France; CNRS / LAM, France), Christian Ginski (Sterrewacht Leiden, The Netherlands), Julien H. Girard (ESO, Chile; CNRS / IPAG, France), Dean Hines (STScI, United States), Markus Kasper (ESO, Germany; / IPAG, France), Dimitri Mawet (ESO, Chile), Francois Ménard (University of Chile, Chile), Michael Meyer (ETH Zürich, Switzerland), Claire Moutou (CNRS / LAM, France), Johan Olofsson (Max-Planck- Institut für Astronomie, Germany), Timothy Rodigas (Carnegie Institution of Washington, United States), Jean-Francois Sauvage (ONERA, France, CNRS / LAM, France), Joshua Schlieder (NASA Ames Research Center, United States, Max-Planck- Institut für Astronomie, Germany), Hans Martin Schmid (ETH Zürich, Switzerland), Massimo Turatto (INAF-Osservatorio Astronomico di Padova, Italy), Stephane Udry (Observatoire de Genève, Switzerland), Farrokh Vakili (University of Nice-Sophia Antipolis, France), Arthur Vigan (CNRS / LAM, France, ESO, Chile), Zahed Wahhaj (ESO, Chile, CNRS / LAM, France) and John Wisniewski (Univers ity of Oklahoma, United States).Scientific article:References:-Are you interested? 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