Download Cepheid Variables and the Faulkes Telescope

CEPHEID VARIABLES AND THE FAULKES TELESCOPE
Dr ‘Dill’ Faulkes is a British millionaire who believes that a scientific education is of
such importance to school children that he donates considerable sums of money to
develop projects that benefit students in all manner of scientific and mathematical
areas. One of these projects is the Faulkes Telescope – a pair of robotic, researchgrade, 2-metre aperture telescopes located in Hawaii and New South Wales.
Swinburne University has been assigned the task of managing the educational
programs for Australian schools. The Australian telescope is due for completion in
early 2004.
How far away are the stars?
This question has long been the focus of astronomical research. Early civilisations
built pyramids to climb so that they could be closer to the stars to make better
observations! Up until the early 20th century, the Milky Way was thought to be the
whole universe! The main problem is that light sources appear dimmer as you move
away from them. The relationship is well known (an inverse square law), however, to
determine the distance, you need to know the intrinsic brightness of the object.
As this was not known, it was impossible to accurately measure the distance to the
star. Not until Edwin Hubble discovered cepheid variable stars in M31 (the
Andromeda Galaxy) did astronomers start to get an idea of cosmic distances.
How was this achieved?
For stars relatively close to the Earth, stellar parallax was used. However, this method
was not viable for large distances.
Cepheid variables
A cepheid variable star varies in brightness.
Around 1908, while examining photographic
plates of the Large Magellanic Cloud, the
American astronomer Henrietta Leavitt found
that there was a relationship between the
brightness of the stars and the period of the
luminosity cycle: the brighter the star, the
longer the period. Using parallax methods,
astronomers then worked out how to link the
period of the cepheid to the absolute
luminosity of the star.
Type Ia supernovae
Most stars form in pairs. The formation process usually results in pairs of stars that
are at slightly different stages of their lifecycles. This may lead to a situation where a
white dwarf star orbits a red giant. The white dwarf draws material from the outer
layers of the red giant onto its surface. This material heats up until fusion starts and
the entire white dwarf is consumed in a runaway thermonuclear reaction.
Astronomers believe that the intrinsic brightness of this process is nearly constant.
This allows the distance to the supernova to be calculated.
Supernovae are relatively rare but important events for astronomers. The chance to
observe the process is eagerly sought after. However, research telescopes cannot
afford the time to search for such random events. Fortunately, there are thousands of
amateur astronomers who search for just such events and notify the astronomical
community (a process greatly assisted by the advent of email) who then turn their
large telescopes all around the world towards the event.
(Picture: Space Telescope Science Institute and NASA)
Supernova 1994D
The Faulkes Telescope
To obtain the required measurements of cepheid variables or to detect a distant
Supernova, a quality telescope is required. A larger telescope will allow more distant
events to be detected. Along with the telescope, a method of recording the data is
required. In the past this was done with photographic plates. Today, however, CCD
cameras are being used because they digitise the data. This allows easy analysis and
storage of the images on computers.
The Faulkes Telescope is a telescope built purely for students to use. It allows
students to access a large (2-metre aperture) telescope via the Internet. Appropriate
image – analysis software is provided to allow you to go hunting for your own
supernova or measure your own cepheid variables.
The Centre for Astrophysics and Supercomputing is keen for students to use this new
facility and share in the new discoveries that new technology allows.
Charles Sturt University has a similar program with a smaller robotic telescope.
The Faulkes Telescope under construction.
Note the size of the worker! (Picture: Telescope
Technologies Limited)