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Astronomy

In the heart of Eta Carinae

ESO / Gerd Weigelt Cloud of gas and dust enveloping star (left) and detailed view of Eta Carinae: stellar winds collide at 10 million kilometers an hourESO / Gerd Weigelt

Using interferometry techniques in the infrared range to deliver images 50,000 times sharper than the human eye, a team of astrophysicists led by Gerd Weigelt, from the Max Planck Institute for Radioastronomy (MPIfR), in Bonn, Germany, observed the massive two-star system Eta Carinae at an unprecedented level of detail (Astronomy & Astrophysics, October 19, 2016). By imaging the collision zone for stellar winds (flows of charged particles that are ejected from the surface of stars), researchers were able to calculate the speed at which they crash into each other – that is, about 10 million kilometers an hour. The larger, primary star, Eta Carinae A, has a solar mass of roughly 100 and is five million times brighter than the Sun. The secondary star, Eta Carinae B, is two-thirds smaller and one-tenth as bright as its bigger sister. “With these observations, we were able to map the zone in which the two stellar winds collide and make sure we genuinely understand the basic parameters of the binary system,” says Augusto Damineli, astrophysicist at the University of São Paulo (USP) and one of three Brazilians taking part in the study. Eta Carinae is enveloped by a dense double-lobed nebula called the Homunculus, which is a cloud of gas and dust that further hampers observation. The latest images of the system were captured using the Very Large Telescope Interferometer (VLTI) at the European Southern Observatory (ESO).

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