SLA_RVLSRD

RV Corrn to Dynamical LSR

ACTION:

Velocity component in a given direction due to the Sun’s motion with respect to the “dynamical” Local Standard of Rest.

CALL:

R = sla_RVLSRD (R2000, D2000)

GIVEN:

RETURNED:

NOTES:

(1)

Sign convention: the result is positive when the Sun is receding from the given point on the sky.

(2)

The Local Standard of Rest used here is the dynamical LSR, a point in the vicinity of the Sun which is in a circular orbit around the Galactic centre. The Sun’s motion with respect to the dynamical LSR is called the peculiar solar motion.

(3)

There is another type of LSR, called a kinematical LSR. A kinematical LSR is the mean standard of rest of specified star catalogues or stellar populations, and several slightly different kinematical LSRs are in use. The Sun’s motion with respect to an agreed kinematical LSR is known as the standard solar motion. The dynamical LSR is seldom used by observational astronomers, who conventionally use a kinematical LSR such as the one implemented in the routine sla_RVLSRK.

(4)

The peculiar solar motion is from Delhaye (1965), in Stars and Stellar Systems, vol 5, p73: in Galactic Cartesian coordinates (+9,+12,+7) km s${}^{-1}$. This corresponds to about 16.6 km s${}^{-1}$ towards Galactic coordinates $l^{II}=53^{\circ },b^{II}=+25^{\circ }$.