What astronomers first thought might be a dying star, unexpectedly turned out
to be a star that has only just been born. Twenty times as heavy as the Sun,
it is less than a million years old - which compared to the 5 billion years
age of the Sun is like a baby of a week old compared to an adult human
The baby star is called IRAS05328-6827, named after the InfraRed Astronomical
Satellite (a predecessor of the Spitzer Space Telescope) and its location on
the sky. It was found in a rather unremarkable location in the Large
Magellanic Cloud (see the picture on the left), which is a very nearby galaxy
of stars and gas: the light from its stars only takes about 165 thousand years
to reach us!
The picture above shows closeup images of the baby star, taken in different
colours of light. The left panel shows a picture in very red "optical" light
that the human eye can just about see. The baby star is invisible, because it
is surrounded by a dust cloud that does not let the starlight out. The middle
panel shows a picture in "infrared" light, which the human eye cannot see but
a special detector can. The baby star shows up well, because the dust is not
so effective in blocking this type of light. The right panel shows a picture
taken with Spitzer - the baby star is extremely bright. The light that we see
here is "warmth" radiating from the dust.
We unravelled the light into its different colours, like rain drops make a
rainbow out of the sunlight. We call this a "spectrum". The colour becomes
redder as it increases in number ("wavelength", measured in micro-metres).
Stuff absorbs light of specific colours. The other way 'round, if light of a
particular colour is being absorbed, we can figure out what stuff did that.
The spectrum shown in the top panel we took with the European Southern
Observatory's Very Large Telescope in the Chilean Atacama desert, whilst the
bottom panel shows the spectrum we took using Spitzer.|
Our baby star is sitting inside a thick dust cloud. Much of the dust is
composed of silicates, quite similar to the sand on the beach. Because the
dust blocks the light it gets quite cold in the cloud - it is like sitting in
the shade on a sunny Winter's day. In fact, it gets much colder in the cloud
than it ever gets in an Antartic Winter. It is not surprising then that we
find lots of ice out there! Water ice, but even ice made up of methanol, and
of carbon dioxide - which on Earth is the gas we breath out!
This research has now been published as a
Letter in the Monthly Notices of the Royal Astronomical Society.