Interferometry of massive stars
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.