scholarly journals Kinematics of RR Lyrae stars in the Galactic bulge with OGLE-IV and Gaia DR2

2020 ◽  
Vol 498 (4) ◽  
pp. 5629-5642
Author(s):  
Hangci Du ◽  
Shude Mao ◽  
E Athanassoula ◽  
Juntai Shen ◽  
Pawel Pietrukowicz
Keyword(s):  
Velocity Dispersion ◽  
Line Of Sight ◽  
Proper Motions ◽  
Galactic Bulge ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Halo Stars ◽  
Central Regions ◽  
Lyrae Stars ◽  
Gaia Dr2

ABSTRACT We analyse the kinematics and spatial distribution of 15 599 fundamental-mode RR Lyrae (RRL) stars in the Milky Way bulge by combining OGLE-IV photometric data and Gaia DR2 proper motions. We show that the longitudinal proper motions and the line-of-sight velocities can give similar results for the rotation in the Galactic central regions. The angular velocity of bulge RRLs is found to be around 35 km s−1 kpc−1, significantly smaller than that for the majority of bulge stars (50–60 km s−1 kpc−1); bulge RRLs have larger velocity dispersion (120–140 km s−1) than younger stars. The dependence of the kinematics of the bulge RRLs on their metallicities is shown by their rotation curves and spatial distributions. Metal-poor RRLs ([Fe/H]<−1) show a smaller bar angle than metal-rich ones. We also find clues suggesting that RRLs in the bulge are not dominated by halo stars. These results might explain some previous conflicting results over bulge RRLs and help understand the chemodynamical evolution of the Galactic bulge.

scholarly journals 3.17. MACHO RR Lyrae stars in the Galactic bulge: the spatial distribution

1998 ◽  
Vol 184 ◽  
pp. 123-124
Author(s):  
D. Minniti ◽  
C. Alcock ◽  
D. Alves ◽  
K. Cook ◽  
S. Marshall ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Density Distribution ◽  
Surface Density ◽  
Galactic Bulge ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Type C ◽  
Type Ab ◽  
Lyrae Stars

We have analyzed a sample of 1150 type ab, and 550 type c RR Lyrae stars found in 24 of 94 bulge fields of the MACHO database. These fields cover a range in Galactocentric distances from 0.3 to 1.6 kpc. In combination with the data on the outer bulge fields of Alard (1997) and Wesselink (1987), here we present the surface density distribution of bulge RR Lyrae between 0.3 and 3 kpc.

scholarly journals Detailed study of the Milky Way globular cluster Laevens 3

2019 ◽  
Vol 490 (2) ◽  
pp. 1498-1508
Author(s):  
Nicolas Longeard ◽  
Nicolas Martin ◽  
Rodrigo A Ibata ◽  
Michelle L M Collins ◽  
Benjamin P M Laevens ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Magnitude Diagram ◽  
Mass Segregation ◽  
Stellar Properties ◽  
Lyrae Stars ◽  
Gaia Dr2

ABSTRACT We present a photometric and spectroscopic study of the Milky Way satellite Laevens 3. Using MegaCam/Canada–France–Hawaii Telescope $g$ and $i$ photometry and Keck II/DEIMOS multi-object spectroscopy, we refine the structural and stellar properties of the system. The Laevens 3 colour–magnitude diagram shows that it is quite metal-poor, old ($13.0 \pm 1.0$ Gyr), and at a distance of $61.4 \pm 1.0$ kpc, partly based on two RR Lyrae stars. The system is faint ($M_V = -2.8^{+0.2}_{-0.3}$ mag) and compact ($r_h = 11.4 \pm 1.0$ pc). From the spectroscopy, we constrain the systemic metallicity (${\rm [Fe/H]}_\mathrm{spectro} = -1.8 \pm 0.1$ dex) but the metallicity and velocity dispersions are both unresolved. Using Gaia DR2, we infer a mean proper motion of $(\mu _\alpha ^*,\mu _\delta)=(0.51 \pm 0.28,-0.83 \pm 0.27)$ mas yr−1, which, combined with the system’s radial velocity ($\langle v_r\rangle = -70.2 \pm 0.5 {\rm \, km \,\, s^{-1}}$), translates into a halo orbit with a pericenter and apocenter of $40.7 ^{+5.6}_{-14.7}$ and $85.6^{+17.2}_{-5.9}$ kpc, respectively. Overall, Laevens 3 shares the typical properties of the Milky Way’s outer halo globular clusters. Furthermore, we find that this system shows signs of mass segregation that strengthens our conclusion that Laevens 3 is a globular cluster.

scholarly journals THE EXTINCTION TOWARD THE GALACTIC BULGE FROM RR LYRAE STARS

2008 ◽  
Vol 135 (2) ◽  
pp. 631-636 ◽  
Author(s):  
Andrea Kunder ◽  
Piotr Popowski ◽  
Kem H. Cook ◽  
Brian Chaboyer
Keyword(s):  
Galactic Bulge ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars
Sign in / Sign up

Export Citation Format

Share Document