2014A&A...563A..60A


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.09CET17:53:42

2014A&A...563A..60A - Astronomy and Astrophysics, volume 563A, 60-60 (2014/3-1)

Constraints on the Galactic bar from the Hercules stream as traced with RAVE across the Galaxy.

ANTOJA T., HELMI A., DEHNEN W., BIENAYME O., BLAND-HAWTHORN J., FAMAEY B., FREEMAN K., GIBSON B.K., GILMORE G., GREBEL E.K., KORDOPATIS G., KUNDER A., MINCHEV I., MUNARI U., NAVARRO J., PARKER Q., REID W.A., SEABROKE G., SIEBERT A., STEINMETZ M., WATSON F., WYSE R.F.G. and ZWITTER T.

Abstract (from CDS):

Non-axisymmetries in the Galactic potential (spiral arms and bar) induce kinematic groups such as the Hercules stream. Assuming that Hercules is caused by the effects of the outer Lindblad resonance of the Galactic bar, we model analytically its properties as a function of position in the Galaxy and its dependence on the bar's pattern speed and orientation. Using data from the RAVE survey we find that the azimuthal velocity of the Hercules structure decreases as a function of Galactocentric radius, in a manner consistent with our analytical model. This allows us to obtain new estimates of the parameters of the Milky Way's bar. The combined likelihood function of the bar's pattern speed and angle has its maximum for a pattern speed of Ωb=(1.89±0.08)xΩ0, where Ω0 is the local circular frequency. Assuming a solar radius of 8.05kpc and a local circular velocity of 238 km/s, this corresponds to Ωb=56±2km/s/kpc. On the other hand, the bar's orientation φb cannot be constrained with the available data. In fact, the likelihood function shows that a tight correlation exists between the pattern speed and the orientation, implying that a better description of our best fit results is given by the linear relation Ωb0=1.91+0.0044(φb(deg)-48), with standard deviation of 0.02. For example, for an angle of φb=30° the pattern speed is 54.0±0.5km/s/kpc. These results are not very sensitive to the other Galactic parameters such as the circular velocity curve or the peculiar motion of the Sun, and are robust to biases in distance.

Abstract Copyright:

Journal keyword(s): Galaxy: kinematics and dynamics - Galaxy: structure - Galaxy: disk - Galaxy: evolution

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3293 3
2 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11082 0
3 * ksi Her LP* 17 57 45.8857114 +29 14 52.367509 5.34 4.64 3.70 3.01 2.55 G8.5III 220 0
4 NAME Pleiades Moving Group MGr ~ ~           ~ 228 1
5 NAME Galactic Bar reg ~ ~           ~ 830 0
6 NAME Coma Berenices Moving Group MGr ~ ~           ~ 51 0
7 NAME Hyades Moving Group MGr ~ ~           ~ 227 1
8 NAME Hercules Stream MGr ~ ~           ~ 169 0
9 NAME Sirius Moving Group MGr ~ ~           ~ 71 0

    Equat.    Gal    SGal    Ecl

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2019.12.09-17:53:42

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