| Subject | 
has spectral type | 
has surface temperature | 
is an instance of | 
has optical brightness variation | 
has observational problem | 
has color | 
has symbol | 
is a kind of | 
has name designated with | 
has observable variation time scale | 
has synonym | 
has definition | 
has luminosity class | 
| dwarf |   | greater than 1000 Kelvin |   |   |   |   | d | star |   |   | main sequence star | Star with mass equal to or less than that of the sun. More generally, any star on or below the main sequence in the Hertzprung-Russell diagram. | V | 
| G star | cooler than G2 | 5000 to 6000 K |   |   |   | yellowish |   | late star |   |   |   | Yellowish star in which the H and K lines of Ca II have become dominant and in which a tremendous profusion of spectral lines of both neutral and ionized metals, particularly iron, begins to show. The Balmer lines of hydrogen are still recognizable. Examples are the Sun and Capella. |   | 
| T Tauri star | cooler than G2 | greater than 1000 Kelvin |   | 0.2 magnitudes or greater | some difficulty in distinguishing between various kinds |   |   | emission line star | - R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name
 - RR, RS, RT, RU, RV, RW, RX, RY, or RZ and the genitive of the latin constellation name when the single letter designations are exhausted
 - AA...AZ, BB...BZ, etc. (omitting J), which ends with QQ...QZ and the genitive of the latin constellation namewhen the RR...RZ designations are exhausted
 - V 335, V 336, etc., when the double letter designations are exhausted
 
  | within a period of decades | nebular variable | Also called T Tauri variable, a type of variable star of spectral classification F, G or K (giants above the main sequence on the Hertzsprung-Russell diagram) that loses an appreciable proportion of its mass in its (irregular) more luminous periods, and is thus surrounded by volumes of gas and dust. |   | 
| RW Aurigae | G5e V | 5000 to 6000 K | dwarf | 0.2 magnitudes or greater | some difficulty in distinguishing between various kinds | yellowish | d |   | - R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name
 - RR, RS, RT, RU, RV, RW, RX, RY, or RZ and the genitive of the latin constellation name when the single letter designations are exhausted
 - AA...AZ, BB...BZ, etc. (omitting J), which ends with QQ...QZ and the genitive of the latin constellation namewhen the RR...RZ designations are exhausted
 - V 335, V 336, etc., when the double letter designations are exhausted
 
  | within a period of decades | nebular variable | A T Tauri star with a strong ultraviolet excess. | V |