List of common astronomy symbols

This is a compilation of symbols commonly used in astronomy, particularly professional astronomy.

Age (stellar)

τ - age

Astrometry parameters

Cosmological parameters

Distance description

Distance description for orbital and non-orbital parameters:

d - distance
- d - in km = kilometer
- d - in mi = mile
- d - in AU = astronomical unit
- d - in ly = light-year
- d - in pc = parsec
- d - in kpc = kiloparsec (1000 pc)
D_L - luminosity distance, obtaining an objects distance using only visual aspects

Galaxy comparison

Galaxy type and spectral comparison:

see galaxy morphological classification

Luminosity comparison

Luminosity comparison:

L_S, L_☉ - luminosity of the Sun

Luminosity of certain object:

L_acc - accretion luminosity
L_bol - bolometric luminosity

Mass comparison

Mass comparison:

M_E, M_E - mass of Earth
M_J, M_♃ - mass of Jupiter
M_S, M_☉ - mass of the Sun

Mass of certain object:

M_●^[1] - mass of black hole
M_acc - mass of accretion disc

Metallicity comparison

Metallicity comparison:

[Fe/H] - Ratio of Iron to Hydrogen. This is not an exact ratio, but rather a logarithmic representation of the ratio of a star's iron abundance compared to that of the Sun.
- for a given star (﹡) : $[{\ce {Fe/H}}]=\log[{\ce {Fe/H}}]_{*}-\log[{\ce {Fe/H}}]_{\odot }$ , where the values represent the number densities of the given element.
[M/H] - Metallicity ratio.
Z - Metallicity
Z_☉, Z_S - Metallicity of the Sun

Orbital parameters

Orbital Parameters of a Cosmic Object:

α - RA, right ascension, if the Greek letter does not appear, á letter will appear.
δ - Dec, declination, if the Greek letter does not appear, ä letter will appear.
P or P_orb or T - orbital period
a - semi-major axis
b - semi-minor axis
q - periapsis, the minimum distance
Q - apoapsis, the maximum distance
e - eccentricity
i - inclination
Ω - longitude of ascending node
ω - argument of periapsis
R_L - Roche lobe
M - Mean anomaly
M_o - Mean anomaly at epoch

Radius comparison

Radius comparison:

R_E, R_🜨 - Radius compared to Earth
R_J, R_♃ - Radius compared to Jupiter
R_S, R_☉ - Radius compared to The Sun

Spectral comparison

Spectral comparison:

see Stellar classification
m_(object) - Apparent magnitude
M_(object) - Absolute magnitude, for galaxies and stars
H_(object) - Absolute magnitude, for planets and nonstellar objects

Temperature description

Temperature description:

T_eff - Temperature Effect, usually associated with luminous object
T_max - Temperature Maximum, usually associated with non-luminous object
T_avg - Temperature Average, usually associated with non-luminous object
T_min - Temperature Minimum, usually associated with non-luminous object
K - Kelvin

References

^ Kuncic, Z.; Soria, R.; Hung, C. K.; Freeland, M. C.; Bicknell, G. V. (August 2006). "Ultra-luminous X-ray sources: X-ray binaries in a high/hard state?". Proceedings of the International Astronomical Union. 2 (S238): 247–250. arXiv:astro-ph/0611040. doi:10.1017/S1743921307005066. ISSN 1743-9213.

[1] Kuncic, Z.; Soria, R.; Hung, C. K.; Freeland, M. C.; Bicknell, G. V. (August 2006). "Ultra-luminous X-ray sources: X-ray binaries in a high/hard state?". Proceedings of the International Astronomical Union. 2 (S238): 247–250. arXiv:astro-ph/0611040. doi:10.1017/S1743921307005066. ISSN 1743-9213.

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