Free Astronomy Magazine January-February 2016

SPACE CHRONICLES as it enters the final stages of its life. The new observations of the star used the SPHERE instrument on the VLT. The adaptive optics system of this instrument corrects images to a higher degree than earlier adaptive optics systems. This allows features very close to bright sources of light to be seen in great detail. SPHERE clearly revealed how the brilliant light of VY Canis Majoris was light- ing up clouds of material surround- ing it. And by using the ZIMPOL mode of SPHERE, the team could not only peer deeper into the heart of this cloud of gas and dust around the star, but they could also see how the starlight was scattered and po- larised by the sur- rounding material. These measure- ments were key to discovering the elusive properties of the dust. (The images in the new study are also tak- en in visible light — shorter wave- lengths than the near-infrared re- gime, where most earlier adaptive op- tics imaging was performed. These two factors result in signifi- cantly sharper im- ages than earlier VLT images. Even higher spatial res- olution has been achieved with the VLTI, but the in- terferometer does not create images Aging star’s weight loss secret revealed by ESO A team of astronomers using ESO’s Very Large Telescope (VLT) has captured the most detailed images ever of the hyper- giant star VY Canis Majoris. These ob- servations show how the unexpect- edly large size of the particles of dust surrounding the star enable it to lose an enor- mous amount of mass as it begins to die. This process, un- derstood now for the first time, is necessary to pre- pare such gigantic stars to meet ex- plosive demises as supernovae. VY Ca- nis Majoris is a stel- lar goliath, a red hypergiant, one of the largest known stars in the Milky Way. It is 30–40 times the mass of the Sun and 300,000 times more lumi- nous. In its current state, the star would encompass the orbit of Jupi- ter, having expand- ed tremendously T his wide-field view shows the sky around the very brilliant red hypergiant star VY Canis Majoris, one of the largest stars known in the Milky Way. The star itself appears at the centre of the picture, which also includes clouds of glow- ing red hydrogen gas, dust clouds and the bright star cluster around the bright star Tau Canis Majoris towards the upper right. This picture was created from images forming part of the Digitized Sky Survey 2. [ESO/Digitized Sky Survey 2]