Table C.1.
Properties of the Sun relative to the Galactic center, as used by Astropy 4.0.
| Description | Values | Ref. |
|---|---|---|
| Galactocentric Frame (ICRS) | (αGC, δGC) = (266.4051, −28.936175) deg | 1 |
| Galactocentric distance of Sun | d⊙ = 8.122 kpc | 2 |
| Distance of Sun to Galactic mid-plane | Z⊙ = 20.8 pc | 3 |
| Solar velocity in Galactocentric cylindrical coordinates | (vR, ⊙, vϕ, ⊙, vZ, ⊙) = (−12.9, 245.6, 7.78) km s−1 | 4, 1, 2 |
| LSR motion in Galactocentric cylindrical coordinates | (vR, LSR, vϕ, LSR, vZ, LSR) = (1.8, 233.4, 0.53) km s−1 | 4 |
| Barycentric standard solar motion relative to LSR since 2010 | (U⊙, V⊙, W⊙) = (11.1, 12.24, 7.25) km s−1 | 5 |
| Barycentric standard solar motion relative to LSR since 1986 (a) | (U⊙, V⊙, W⊙) = (10.0, 15.4, 7.8) km s−1 | 6 |
| Barycentric standard solar motion relative to LSR since 1981 (b) | (U⊙, V⊙, W⊙) = (9.2, 12.0, 6.9) km s−1 | 7 |
Notes.
The standard solar motion of 20 km s−1 toward l = 56°, b = 23° (RA = 18h, Dec = 30°, epoch 1900) was recommended by the IAU (see, e.g., Kerr & Lynden-Bell 1986) and is likely often used by radio observatories to convert gas radial velocities, as derived from molecular line observations, from vHEL to vLSR, and is given here for completeness (not used by Astropy 4.0).
The standard solar motion of 16.6 km s−1 is reported in Mihalas & Binney (1981) and was likely used by Maddalena et al. (1986) and is given here for completeness (not used by Astropy 4.0).
References. (1) Reid & Brunthaler (2004); (2) Gravity Collaboration (2018); (3) Bennett & Bovy (2019); (4) Drimmel & Poggio (2018); (5) Schönrich et al. (2010); (6) Kerr & Lynden-Bell (1986); (7) Mihalas & Binney (1981).
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