Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters
This Letter presents a study of the geometry and motion of the Galactic disk using open clusters in the Gaia era. The findings suggest that the inclination θ _i of the Galactic disk increases gradually from the inner to the outer disk, with a shift in orientation at the Galactocentric radius of appr...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/ace77d |
| _version_ | 1797697907002966016 |
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| author | Zhihong He |
| author_facet | Zhihong He |
| author_sort | Zhihong He |
| collection | DOAJ |
| description | This Letter presents a study of the geometry and motion of the Galactic disk using open clusters in the Gaia era. The findings suggest that the inclination θ _i of the Galactic disk increases gradually from the inner to the outer disk, with a shift in orientation at the Galactocentric radius of approximately 6 ± 1 kpc. Furthermore, this study brings forth the revelation that the mid-plane of the Milky Way may not possess a stationary or fixed position. A plausible explanation is that the inclined orbits of celestial bodies within our Galaxy exhibit a consistent pattern of elliptical shapes, deviating from perfect circularity; however, more observations are needed to confirm this. An analysis of the vertical motion along the Galactocentric radius reveals that the disk has warped with precession and that the line of node shifts at different radii, aligning with the results from the classical Cepheids. Although there is uncertainty for precession/peculiar motion in solar orbit, after considering the uncertainty, the study derives a median value of ${\dot{\phi }}_{\mathrm{LON}}$ = 6.8 km s ^−1 kpc ^−1 in the Galaxy. This value for the derived precession in the outer disk is lower than those in the literature due to the systematic motion in solar orbit ( θ _i = 0.°6). The study also finds that the inclinational variation of the disk is significant and can cause systematic motion, with the variation rate ${\dot{\theta }}_{i}$ decreasing along the Galactic radius with a slope of −8.9 μ as yr ^−1 kpc ^−1 . Moreover, the derived ${\dot{\theta }}_{i}$ in solar orbit is 59.1 ± 11.2 _sample ± 7.7 ${}_{{V}_{Z\odot }}$ μ as yr ^−1 , which makes it observable for high-precision astrometry. |
| first_indexed | 2024-03-12T03:46:39Z |
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| id | doaj.art-8f9a68f2e0ce493cb960f67df9f0343f |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T03:46:39Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-8f9a68f2e0ce493cb960f67df9f0343f2023-09-03T12:49:30ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019541L910.3847/2041-8213/ace77dGeometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open ClustersZhihong He0https://orcid.org/0000-0002-6989-8192School of Physics and Astronomy, China West Normal University , No. 1 Shida Road, Nanchong 637002, People's Republic of China ; hezh@cwnu.edu.cnThis Letter presents a study of the geometry and motion of the Galactic disk using open clusters in the Gaia era. The findings suggest that the inclination θ _i of the Galactic disk increases gradually from the inner to the outer disk, with a shift in orientation at the Galactocentric radius of approximately 6 ± 1 kpc. Furthermore, this study brings forth the revelation that the mid-plane of the Milky Way may not possess a stationary or fixed position. A plausible explanation is that the inclined orbits of celestial bodies within our Galaxy exhibit a consistent pattern of elliptical shapes, deviating from perfect circularity; however, more observations are needed to confirm this. An analysis of the vertical motion along the Galactocentric radius reveals that the disk has warped with precession and that the line of node shifts at different radii, aligning with the results from the classical Cepheids. Although there is uncertainty for precession/peculiar motion in solar orbit, after considering the uncertainty, the study derives a median value of ${\dot{\phi }}_{\mathrm{LON}}$ = 6.8 km s ^−1 kpc ^−1 in the Galaxy. This value for the derived precession in the outer disk is lower than those in the literature due to the systematic motion in solar orbit ( θ _i = 0.°6). The study also finds that the inclinational variation of the disk is significant and can cause systematic motion, with the variation rate ${\dot{\theta }}_{i}$ decreasing along the Galactic radius with a slope of −8.9 μ as yr ^−1 kpc ^−1 . Moreover, the derived ${\dot{\theta }}_{i}$ in solar orbit is 59.1 ± 11.2 _sample ± 7.7 ${}_{{V}_{Z\odot }}$ μ as yr ^−1 , which makes it observable for high-precision astrometry.https://doi.org/10.3847/2041-8213/ace77dMilky Way GalaxyOpen star clustersGalaxiesGalaxy disksGalaxy structure |
| spellingShingle | Zhihong He Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters The Astrophysical Journal Letters Milky Way Galaxy Open star clusters Galaxies Galaxy disks Galaxy structure |
| title | Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters |
| title_full | Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters |
| title_fullStr | Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters |
| title_full_unstemmed | Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters |
| title_short | Geometry and Kinematics of a Dancing Milky Way: Unveiling the Precession and Inclination Variation across the Galactic Plane via Open Clusters |
| title_sort | geometry and kinematics of a dancing milky way unveiling the precession and inclination variation across the galactic plane via open clusters |
| topic | Milky Way Galaxy Open star clusters Galaxies Galaxy disks Galaxy structure |
| url | https://doi.org/10.3847/2041-8213/ace77d |
| work_keys_str_mv | AT zhihonghe geometryandkinematicsofadancingmilkywayunveilingtheprecessionandinclinationvariationacrossthegalacticplaneviaopenclusters |