def asini_c(pb, mf):
    """
    asini_c(pb, mf):
        Return the orbital projected semi-major axis (lt-sec) given:
            'pb' is the binary period in sec.
            'mf' is the mass function of the orbit.
    """
    return (mf * pb * pb / 8015123.37129)**(1.0 / 3.0)