pint.derived_quantities.a1sini

pint.derived_quantities.a1sini(mp, mc, pb, i=<Quantity 90. deg>)[source]

Pulsar’s semi-major axis.

The full semi-major axis is given by Kepler’s third law. This is the projection (\(\sin i\)) of just the pulsar’s orbit (\(m_c/(m_p+m_c)\) times the full semi-major axis), which is what pulsar timing measures. Can handle scalar or array inputs.

Parameters:

mp (astropy.units.Quantity) – pulsar mass
mc (astropy.units.Quantity) – companion mass
pb (astropy.units.Quantity) – Binary orbital period
i (astropy.coordinates.Angle or astropy.units.Quantity) – orbital inclination

Returns:

a1sini – Projected semi-major axis of pulsar’s orbit in pint.ls

Return type:

astropy.units.Quantity

Raises:

astropy.units.UnitsError – If the input data are not appropriate quantities
TypeError – If the input data are not quantities

Notes

Calculates

\[\frac{a_p \sin i}{c} = \frac{m_c \sin i}{(m_p+m_c)^{2/3}} G^{1/3}\left(\frac{P_b}{2\pi}\right)^{2/3}\]

More details in Timing Models. Also see [8]