Minimum mass

In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets. Because most extrasolar planets are currently detected by the radial velocity method, which reveals planets by measuring changes in the movement of stars in the line-of-sight, the real orbital inclinations and true masses of the planets are generally unknown.

If inclination can be determined, the true mass can be obtained from the calculated minimum mass using the following relationship:

$M_\text{true} = \frac{M_\min}{\sin i} \,$

For orbiting bodies in extrasolar stellar and planetary systems, an inclination of 0° or 180° corresponds to a face-on orbit, while an inclination of 90° corresponds to an edge-on orbit.

References

• Kuchner, Marc J.; Kuchner, Marc J. (09-2004). "A Minimum-Mass Extrasolar Nebula". The American Astronomical Society 612 (2): 1147–1151. Bibcode 2004ApJ...612.1147K. doi:10.1086/422577. 
• "The minimum mass ratio of W UMa-type binary systems". Monthly Notes of the Royal Astronomical Society 377 (4): 1635–1637. June 2007. Bibcode 2007MNRAS.377.1635A. doi:10.1111/j.1365-2966.2007.11723.x. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2966.2007.11723.x?cookieSet=1&journalCode=mnr. Retrieved 2008-05-24.