A Class X star is a super rare star. Out of a sextillion stars, there could be only hundreds of them. While there are Luminous Blue Variables, Wolf-Rayet stars, and Navy-Blue stars that are generally more powerful than O-class stars, those types mentioned aren't main sequence stars, while Class X stars can be.
The Class X stars theoretically live for only 100,000 years, then would become red metagiants, and explode into extreme metanovas, then live a superpowered black hole absorbing nearby objects light years away.
Their habitable zones would be a few thousand AUs away, which is a fraction of a light-year!
Generally, these stars would be from light bluey purple (X9) to light violet (X5) to light pure purple (X0), in terms of color. The fact that purple light can't be currently seen hinders confirmation that these stars do exist.
|Spectral type||Mass||Luminosity||Temperature (Fahrenheit)|
|Φ · Ψ · Ω · Q · DE · GR · σ ς · Θ · N · D · BS · Y · T · L · M · C · S · QS · K · G · F · A · B · LBV · β · O · W · N · X · n0 · Exotic (Π · Σ · Γ · Δ · μ) · δ · I · TŻO · BL · ℃ · ⩡|