Physical GMC data

Quantity

Units

Number

4000

dimensionless

Mass

2 × 10⁵

$M_{\odot }$ solar masses

Mean diameter

45

parsec

Projected surface area

45

parsec²

Volume

10⁵

parsec³

Volume density ( $H_2$ )

3 × 10¹¹

m⁻³

Alkaline density ( $\frac{N_{alk}}{H_2}$ )

5 × 10⁻³

Mean surface density

1.5 × 10¹²⁴

m⁻²

Mean separation

500

parsec

Orion GMC distance $D_{\max }$ to Observer

640

light-years