Download Variable Star Observation

Variable Star Observation
By: Jessica Vaughn
Variable Stars
• What are variable stars?
• Variable stars are stars that change brightness. The brightness
changes of these stars can range from a thousandth of a
magnitude to as much as twenty magnitudes Variable stars are
stars that change brightness. The brightness changes of these
stars can range from a thousandth of a magnitude to as much
as twenty magnitudes over periods of a fraction of a second to
years, depending on the type of variable star , depending on
the type of variable star. (AAVSO)
A Brief History of Variable Stars
• The first variable stars were discovered around 1600
• Aristotle and other ancient philosophers taught that stars weren’t
completely invariable.
• Some of the first variable stars were found by scientists from 15001890.
•
The latest edition of the General catalogue of Variable Stars (2003) lists
nearly 40,000 variable stars in our own galaxy, as well as 10,000 in other
galaxies, and over 10,000 'suspected' variables. (AAVSO)
What types of variable stars are
there?
• There are two different types of variable
stars and four main classes.
• Types of variable stars:
• Intrinsic
• Extrinsic
Pulsating and Eruptive stars
• Within the intrinsic
group are two classes
of stars: pulsating and
eruptive.
• Pulsating variables
are stars that show
periodic expansion
and contraction of
their surface layers.
(AAVSO)
Eruptive (Cataclysmic) variables
• Eruptive variables (also
known as cataclysmic
variables), as the name
implies, are stars that
have occasional violent
outbursts caused by
thermonuclear processes
either in their surface
layers or deep within their
interiors. An example of a
cataclysmic variable is a
supernova.
Eclipsing binary and rotating stars
• Eclipsing binary and
rotating stars are the
two classes of stars
within the extrinsic
group.
• A binary star is a
stellar system
consisting of two stars
orbiting around their
center of mass.
Rotating stars
• Rotating stars are
stars that show small
changes in brightness
due to dark or bright
spots, or patches on
their stellar system.
Rotating stars are
often binary systems.
Observing Variable Stars
• Variable stars can be observed through
many ways such as photometry,
spectrophotometry and spectroscopy.
• A light curve is more commonly used to
observe a star’s brightness compared to
non-variable stars of known magnitude.
Light Curve
• A light curve is a chart
used to show the
brightness of a star
(in magnitude) verses
time. The time is
plotted in Julian date
(JD).
• The magnitude is
plotted on the Y-axis
• Time is plotted on the
X-axis.
Why observe variable stars?
• By understanding
variable stars and
what makes them
vary in brightness,
scientists can start to
understand other
stars and their
behavior. It also helps
to find information on
stellar properties.
More info
• There are various groups in the world that
are studying variable stars. These are two
I got information from.
• AAVSO ( American Association of
Variable Star Observers )
• BAA (British Astronomical Association)