<aside> 💡 Disambiguation: (Harvard) Spectral type = OBAFGKM, (MK) luminosity class = I,II,III,IV,V etc., spectral class = G2V (e.g.)
</aside>
| Type | O | B | A | F | G | K | M |
|---|---|---|---|---|---|---|---|
| Max temp (effective) | $\infin$ | 33000 | 10000 | 7300 | 6000 | 5300 | 3900 |
| (to 2300) |
Within the classes, 0 is the hottest and 9 is the coolest, evenly spaced in a logarithmic temperature scale
| 0/Ia | Iab | Ib | II | III |
|---|---|---|---|---|
| Hypergiant | Luminous supergiant | intermediate-size luminous supergiant | Less luminous supergiant | Bright giant |
| IV | V | VI | VII | |
| Subgiant | Main-sequence stars (dwarfs) | Subdwarfs | White dwarfs |
<aside> 💡 Electron temperature can be associated with energy using this relation: $E=k_BT$ Also, some questions use the particle nature of light.
</aside>
See fundamental astro ch. 5
Hydrostatic equilibrium (pressure continuity):
$$ \frac{dP}{dr}=-\frac{GM_r\rho}{r^2} $$
This is the net effect, and still allows for convection. In other words it is averaged over the shell at $r$
Similarly, the mass continuity equation:
$$ \frac{d M_r}{dr}=4\pi r^2 \rho $$
Energy conservation ($\epsilon$ is the energy produced per unit volume):
$$ \frac{d L_r}{dr}=4 \pi r^2\rho \epsilon $$