Some Terms You Should Know: the Crab Nebula
These are some terms you will come across in your lab class dealing with
the Crab Nebula.
A large region of dust and gas in space. The plural is nebulae.
A star that suddenly flares up in brightness. This is possibly due
to the nuclear reactions resulting from new material being deposited on
the surface of a white dwarf. The plural is novae.
A distance equal to 3.26 light years. An object one parsec away will have
a parallax angle of 1 second of arc when viewed from a baseline
of 1 AU.
A conversion factor, for a specific photograph, of linear distance to angular
distance (e.g., from mm to seconds of arc).
Motion that is 90 degrees from a line between the observer and the object.
Motion to the left or right, e.g., would be proper motion, while motion
towards you would be radial motion.
A neutron star that spins very rapidly and emits a radio "pulse" at regular
times (usually on the order of seconds).
Back to the definitions page
This page was last updated on 13 April 1998
and is © 1998 by Jim McDonald.