User`s guide

76 Starry Night User’s Guide
Tip: The H-R diagram is fully dynamic. If
you scroll around the screen or change
your field of view, the stars shown
onscreen will change, and the H-R
diagram will update to plot these new
stars.
H-R Diagram Options:
Expand the H-R
Options layer
beneath the H-R
diagram to access
options that affect
the appearance of
the diagram.
Use Absolute Magnitudes: Unchecking
this option will plot apparent magnitude
instead of absolute magnitude on the
vertical axis.
Automatic ranges: Checking this option
will cause Starry Night to select the
smallest possible ranges for the X and Y
axes that still manages to include all stars
visible onscreen.
Image Brightness: This slider controls
how bright the star dots in the H-R
diagram are drawn.
Distance Cut-Off: This plots only those
stars with distances from Earth that lie
between the minimum and maximum
distances that you specify.
Labels: Unchecking this option draws a
blank graph with no labels. Checking this
option allows you to turn on any of the
label options listed below.
Gridlines: Draws gridlines from the
vertical and horizontal axes.
B-V: Uses a stars B-V colour as the field
along the horizontal axis. Hotter stars have
a lower B-V value.
Kelvin X 1000: Plots star temperature (in
thousands of degrees Kelvin) along the
horizontal axis. Degrees Kelvin are equal
to degrees Celsius + 273.
Spectral Class: Plots star spectral class
along the horizontal axis.
Main Sequence: Draws a line representing
stars on the main sequence. Any star that
appears close to this line is probably a
main sequence star (a star that is still
burning hydrogen fuel).
Regions: Labels the areas of red giants,
white dwarfs, and main sequence stars.
Note: White dwarfs are very dim and few
are in Starry Night’s star catalogues (the
Hipparcos/Tycho-2 catalogues), so few
will be found in Starry Night’s H-R
diagrams.
Dim Labels: Draws the diagram labels
much dimmer than the stars.