The number of stars, galaxies, or other objects of different luminosity within a given volume of space (see the accompanying diagram). The luminosity function of a star cluster may be found by counting the number of stars of different apparent magnitudes, since all the stars in the cluster are at roughly the same distance.
luminosity function:
The luminosity function for stars within 20 parsecs of the Sun from Hipparcos data. The number of stars is plotted against their absolute magnitude. The flattening of the slope around 6th–7th magnitude is known as the Wielen dip.
- one-tail probability
- one-time pad
- one-time password
- one-to-one correspondence
- one-to-one function
- one-to-one onto function
- O-network
- one-way filter
- one-way function
- one-way light time
- one-way linked list
- one-way travel time
- one-way valve
- one‐sided surface
- one‐sided test
- one‐tailed test
- one‐to‐many
- one‐to‐one
- one‐to‐one correspondence
- one’s complement
- one’s-complement notation
- onion weathering
- onium ion
- Onizuka, Ellison Shoji (1946–86)
- onlap