## Using VLBI observations of masers for studying the galaxy kinematics

Transactions of IAA RAS, issue 24, 294–298 (2012)

**Keywords**:
radiointerferometry, Galactic rotation parameters, VLBI observations

### Abstract

The spatial velocities of all 28 currently known masers having trigonometric parallaxes, proper motion and line-of-site velocities are reanalyzed using the Bottlinger equations. These masers are associated with 25 active star-forming regions and are located in the range of galactocentric distances 3 < Ρ < 14 kpc. To determine the Galactic rotation parameters, we have used the first three Taylor expansion terms of angular rotation velocity _ at the galactocentric distance of the Sun, Ρ0 = 8 kpc. We have obtained the following solutions: ω = (-31.0 ± 1.2) km·s ^-1·kpc^-1; Oort constants, A = (17.8 ± 0.8) km·s⁻¹·kpc⁻¹, B = (-13.2 ± 1.5) km·s⁻¹·kpc⁻¹; the circular velocity of the solar neighbourhood rotation V0 = (248 ± 14) km·s⁻¹. A Fourier analysis of the galactocentric radial velocities of masers VR has allowed us to estimate the wavelength λ = (2.0 ± 0.2) kpc and peak velocity fR = (6.5 ± 2) km·s⁻¹ of periodic perturbations from the density wave. The phase of the Sun in the density wave is estimated as χ0 ≈ (-130 ± 10)°. Taking into account perturbations evoked by the spiral density wave, we have obtained the following non-perturbed components of the peculiar solar velocity with respect to the local standard of rest (LSR): (U0, V0, W0)LSR = [(5.5, 11, 8.5) ± (2, 2, 1)] km·s⁻¹.

### Citation

`V. V. Bobylev, A. T. Bajkova . Using VLBI observations of masers for studying the galaxy kinematics // Transactions of IAA RAS. — 2012. — Issue 24. — P. 294–298.`

```
@article{bobylev2012,
abstract = {The spatial velocities of all 28 currently known masers having trigonometric parallaxes, proper motion and line-of-site velocities are reanalyzed using the Bottlinger equations. These masers are associated with 25 active star-forming regions and are located in the range of galactocentric distances 3 < Ρ < 14 kpc. To determine the Galactic rotation parameters, we have used the first three Taylor expansion terms of angular rotation velocity _ at the galactocentric distance of the Sun, Ρ0 = 8 kpc. We have obtained the following solutions:
ω = (-31.0 ± 1.2) km·s ^-1·kpc^-1; Oort constants, A = (17.8 ± 0.8) km·s⁻¹·kpc⁻¹, B = (-13.2 ± 1.5) km·s⁻¹·kpc⁻¹;
the circular velocity of the solar neighbourhood rotation V0 = (248 ± 14) km·s⁻¹.
A Fourier analysis of the galactocentric radial velocities of masers VR has allowed us to estimate the wavelength
λ = (2.0 ± 0.2) kpc and peak velocity fR = (6.5 ± 2) km·s⁻¹ of periodic perturbations from the density wave.
The phase of the Sun in the density wave is estimated as χ0 ≈ (-130 ± 10)°. Taking into account perturbations evoked by the spiral density wave, we have obtained the following non-perturbed components of the peculiar solar velocity with respect to the local standard of rest (LSR): (U0, V0, W0)LSR = [(5.5, 11, 8.5) ± (2, 2, 1)] km·s⁻¹.},
author = {V.~V. Bobylev and A.~T. Bajkova},
issue = {24},
journal = {Transactions of IAA RAS},
keyword = {radiointerferometry, Galactic rotation parameters, VLBI observations},
pages = {294--298},
title = {Using VLBI observations of masers for studying the galaxy kinematics},
url = {http://iaaras.ru/en/library/paper/868/},
year = {2012}
}
```

```
TY - JOUR
TI - Using VLBI observations of masers for studying the galaxy kinematics
AU - Bobylev, V. V.
AU - Bajkova, A. T.
PY - 2012
T2 - Transactions of IAA RAS
IS - 24
SP - 294
AB - The spatial velocities of all 28 currently known masers having
trigonometric parallaxes, proper motion and line-of-site velocities
are reanalyzed using the Bottlinger equations. These masers are
associated with 25 active star-forming regions and are located in the
range of galactocentric distances 3 < Ρ < 14 kpc. To determine the
Galactic rotation parameters, we have used the first three Taylor
expansion terms of angular rotation velocity _ at the galactocentric
distance of the Sun, Ρ0 = 8 kpc. We have obtained the following
solutions: ω = (-31.0 ± 1.2) km·s ^-1·kpc^-1; Oort constants, A =
(17.8 ± 0.8) km·s⁻¹·kpc⁻¹, B = (-13.2 ± 1.5) km·s⁻¹·kpc⁻¹; the
circular velocity of the solar neighbourhood rotation V0 = (248 ± 14)
km·s⁻¹. A Fourier analysis of the galactocentric radial velocities
of masers VR has allowed us to estimate the wavelength λ = (2.0 ±
0.2) kpc and peak velocity fR = (6.5 ± 2) km·s⁻¹ of periodic
perturbations from the density wave. The phase of the Sun in the
density wave is estimated as χ0 ≈ (-130 ± 10)°. Taking into account
perturbations evoked by the spiral density wave, we have obtained the
following non-perturbed components of the peculiar solar velocity
with respect to the local standard of rest (LSR): (U0, V0, W0)LSR =
[(5.5, 11, 8.5) ± (2, 2, 1)] km·s⁻¹.
UR - http://iaaras.ru/en/library/paper/868/
ER -
```