Interferometry of massive stars

last updated apr 10th, 2008  •  by willem-jan de wit 

Welcome

This page is dedicated to the formation and early evolution of high-mass stars. Stars are categorised as "high-mass" when they have a total mass more than 8 times that of our sun. This may seem like an odd number to chose, but there are specific reasons why such high-mass stars are extremely interesting, as i will explain below.The past few years we have been using high-resolution imaging techniques in order to understand the earliest phases of their evolution. In particular we use the European Southern Observatory's VLT Interferometer that allows us to observe the smallest details yet of their formation process. This will ultimately lead to a better understanding of these important objects. 


Why  high-mass stars?


High-mass stars are very powerfull cosmic engines owing to their enormous  energy output throughout their existence. They live short and violent lifes, culminating in a spectacular demise in the form of a supernova. Their ultimate fate is to become a neutron star or a black hole. High-mass stars can be a million times more luminous than our sun and thus dominate the radiation energy in galaxies. Their luminous nature is even a hazard to their own existence: they blow large portions of their mass away from their surface into space. In a sense this makes them champion weigh-losers. The mass-loss peaks when a massive star ends its life in a last gigantic blast in the form of a supernova, returning most of the material that was once star back into space. The accumulating interstellar gas and dust becomes the buidling material for new generations of stars, planets and life. My brief sketch of what a massive star consititutes is hopefully convincing enough for you to realize that massive stars are cornerstone to many vital processes that take place throughout the formation and evolution of Galaxies and the Universe. This warrants detailed studies of high-mass stars in order to increase our understanding of these fascinating objects.


The VLTI and ESO

 

One of the world's most powerful telescopes is the Very Large Telescope built
and managed by the European Southern Observatory. The VLT is located
in the very dry Atacama desert at the feet of the Chilean Andes. The weather conditions in the Atacama desert are as perfect as one can get to do astronomical observation from the ground.

The VLT is not one but consists of four telescopes that are optimized for observations in the optical and infrared parts of the electromagnetic spectrum. Each telescope has a a mirror with a diameter of 8.2 meter. The fact that the noun "VLT" has been chosen to be singular conveys something fundamental about the four telescopes: they can operate as a single, gigantic telescope using the principle of interferometry, when they are "locked" together. The VLT is the world's first dedicated optical interferometer open and accessible to the scientific community. The VLT is also the world's most powerfull interferometer, in the sense of its return in astronomical information of one single VLTI observation.


 
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