Download Spectral Class and Colour index

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Timeline of astronomy wikipedia, lookup

CoRoT wikipedia, lookup

Ursa Major wikipedia, lookup

Lyra wikipedia, lookup

Star wikipedia, lookup

H II region wikipedia, lookup

Serpens wikipedia, lookup

Cassiopeia (constellation) wikipedia, lookup

Open cluster wikipedia, lookup

Observational astronomy wikipedia, lookup

Crux wikipedia, lookup

Star catalogue wikipedia, lookup

Corona Borealis wikipedia, lookup

Stellar evolution wikipedia, lookup

Auriga (constellation) wikipedia, lookup

Aries (constellation) wikipedia, lookup

Canis Minor wikipedia, lookup

Hipparcos wikipedia, lookup

Stellar kinematics wikipedia, lookup

IK Pegasi wikipedia, lookup

Canis Major wikipedia, lookup

Cygnus (constellation) wikipedia, lookup

Corona Australis wikipedia, lookup

Star formation wikipedia, lookup

Cosmic distance ladder wikipedia, lookup

Boötes wikipedia, lookup

Stellar classification wikipedia, lookup

Perseus (constellation) wikipedia, lookup

Aquarius (constellation) wikipedia, lookup

Ursa Minor wikipedia, lookup

Corvus (constellation) wikipedia, lookup

Transcript
Spectral Class and Colour index
As we have seen the colour of a star is related to its temperature as a consequence of
Wien’s law.
λmaxT = constant
The spectral class (OBAFGKM) of a main sequence star is also a direct result of its
temperature.
One (relatively crude) way of determining the temperature (and spectral class) of a
star is to measure the relative intensity of the light at two positions in the spectrum
originally by using coloured filters. The wavelengths generally chosen are the blue
(420nm) and the yellow (sometimes called the visual) 540nm
A subtraction gives a B-V
value.
A crude measure of the energy
distribution curve
relative
intensity
λ
Investigating The Nature of the Stars in a Cluster
In the exercise below you are going to investigate the relationship between the
spectral class of the stars, represented by the colour index and the apparent
magnitude of the stars in the cluster. Making the assumption that all of the stars in
the cluster are at the same distance from us, their apparent magnitude will be
representative of their absolute magnitude.