Stellar Classifications

Stars

see also: Gallery of Single Stars

Table: Stellar classification

Class	Temperature	Conventional color	Apparent color	Mass (solar masses)	Radius (solar radii)	Luminosity	% of all Main Sequence Stars
O	30,000–60,000 K	blue	blue	60 M	15 R	1,400,000 L	~0.00003%
B	10,000–30,000 K	blue white	blue white to white	18 M	7 R	20,000 L	0.13%
A	7,500–10,000 K	white	white	3.1 M	2.1 R	80 L	0.6%
F	6,000–7,500 K	yellowish white	white	1.7 M	1.3 R	6 L	3%
G	5,000–6,000 K	yellow	yellow	1.1 M	1.1 R	1.2 L	8%
K	3,500–5,000 K	orange	yellow orange	0.8 M	0.9 R	0.4 L	13%
M	2,000–3,500 K	red	orange red	0.3 M	0.4 R	0.04 L	>78%

The Roman numeral following the Class indicates the size of the star (not presently used here in SFC):

• I - super giant
• II - bright giant
• III - giant
• IV - sub-giant
• V - main sequence
• VI - sub-dwarf
• VII - white dwarf
• VIII - brown

Other Astronomical Objects

These objects are not necessary (or still) stars, nor necessarily natural:

• C - Red/IR star: a star with wavelengths unusually bright in the near-infrared; the strong stellar wind condenses as it cools away from the star, forming molecules such as water (H2O) which can then be pumped to produce dangerous (to shielded ships) maser emissions.
• D - White Dwarf
• NMC/D/E - Nebula (Planetary/Small/Large)
• NMF - Protostar
• P - Neutron Star
• R - Rogue planet (this may be either a terrestrial planet or gas giant)
• S - Infrared star: a star with wavelengths unusually bright in the infrared spectrum, with a powerful magnetic field and emissions of gamma rays.
• T - Station (undesignated)
• U - Unknown (detected but unidentified)
• X - X-ray star; also known as a magnetar, a type of neutron star with an extremely powerful magnetic field and emissions of X-rays and gamma rays.
• Z - Black Hole