a close-up look at one of the biggest stars in the Milky Way, VY Canis Majoris. The final image comes from the SPHERE instrument on ESO’s Very Large Telescope in Chile.
VY Canis Majoris is a stellar 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 luminous. In its current state, the star would encompass the orbit of Jupiter, having expanded tremendously as it enters the final stages of its life.
The new observations of the star using SPHERE clearly revealed how the brilliant light of VY Canis Majoris was lighting up clouds of dusty material surrounding it.
Careful analysis revealed these grains of dust to be comparatively large particles, 0.5 micrometers across, which may seem small, but grains of this size are about 50 times larger than the dust normally found in interstellar space.
Throughout their expansion, massive stars shed large amounts of material – every year, VY Canis Majoris sees 30 times the mass of the Earth expelled from its surface in the form of dust and gas.
This cloud of material is pushed outwards before the star explodes, at which point some of the dust is destroyed, and the rest cast out into interstellar space.
This material is then used, along with the heavier elements created during the supernova explosion, by the next generation of stars, which may make use of the material for planets.
Until now, it had remained mysterious how the material in these giant stars’ upper atmospheres is pushed away into space before the host explodes. The most likely driver has always seemed to be radiation pressure, the force that starlight exerts. As this pressure is very weak, the process relies on large grains of dust, to ensure a broad enough surface area to have an appreciable effect.