The Galactic disc phase spirals at different Galactic positions revealed by Gaia and LAMOST data
| Autor: | Wang, C., Huang, Y., Yuan, H. -B., Xiang, M. -S., Chen, B. -Q., Wang, H. -F., Wu, Y. -Q., Zhang, H. -W., Tian, Z. -J., Yang, Y., Zhang, M., Liu, X. -W. |
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| Rok vydání: | 2019 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/2041-8213/ab1fdd |
| Popis: | We have investigated the distributions of stellar azimuthal and radial velocity components $V_{\Phi}$ and $V_{R}$ in the vertical position-velocity plane $Z$-$V_{Z}$ across the Galactic disc of $6.34 \lesssim R \lesssim 12.34$\,kpc and $|\Phi| \lesssim 7.5^{\circ}$ using a Gaia and Gaia-LAMOST sample of stars. As found in previous works, the distributions exhibit significant spiral patterns. The $V_{R}$ distributions also show clear quadrupole patterns, which are the consequence of the well-known tilt of the velocity ellipsoid. The observed spiral and quadrupole patterns in the phase space plane vary strongly with radial and azimuthal positions. The phase spirals of $V_{\Phi}$ become more and more relaxed as $R$ increases. The spiral patterns of $V_{\Phi}$ and $V_{R}$ and the quadrupole patterns of $V_{R}$ are strongest at $-2^{\circ} < \Phi < 2^{\circ}$ but negligible at $4^{\circ} < \Phi < 6^{\circ}$ and $-6^{\circ} < \Phi < -4^{\circ}$. Our results suggest an external origin of the phase spirals. In this scenario, the intruder, most likely the previously well-known Sagittarius dwarf galaxy, passed through the Galactic plane in the direction towards either Galactic center or anti-center. The azimuthal variations of the phase spirals also help us constrain the passage duration of the intruder. A detailed model is required to reproduce the observed radial and azimuthal variations of the phase spirals of $V_{\Phi}$ and $V_{R}$. Comment: 6pages, 4 figures, Accepted to ApJL |
| Databáze: | arXiv |
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