PERIODIC CHANGES IN THE ORIENTATION OF ORBITS AND THE AGE OF THE GALACTIC BAR
Section: STARS AND THE INTERSTELLAR MEDIUM
Authors:
1.
Sternberg Astronomical Institute, Lomonosov Moscow State University
Faculty of Physics, Lomonosov Moscow State University
Faculty of Physics, Lomonosov Moscow State University
2.
Sternberg Astronomical Institute, Lomonosov Moscow State University
Type:
Сonference article
Published:
27.12.2024
Subject area:
UDC 52
UDC 53
UDC 520
UDC 521
UDC 523
UDC 524
UDC 52-1
UDC 52-6
CSCSTI 41.00
CSCSTI 29.35
CSCSTI 29.31
CSCSTI 29.33
CSCSTI 29.27
CSCSTI 29.05
Russian Classification of Professions by Education 03.06.01
Russian Classification of Professions by Education 03.05.01
Russian Classification of Professions by Education 03.04.03
Russian Library and Bibliographic Classification 2
Russian Library and Bibliographic Classification 223
Russian Trade and Bibliographic Classification 614
Russian Trade and Bibliographic Classification 6135
BISAK SCI004000 Astronomy
BISAK SCI005000 Physics / Astrophysics
UDC 53
UDC 520
UDC 521
UDC 523
UDC 524
UDC 52-1
UDC 52-6
CSCSTI 41.00
CSCSTI 29.35
CSCSTI 29.31
CSCSTI 29.33
CSCSTI 29.27
CSCSTI 29.05
Russian Classification of Professions by Education 03.06.01
Russian Classification of Professions by Education 03.05.01
Russian Classification of Professions by Education 03.04.03
Russian Library and Bibliographic Classification 2
Russian Library and Bibliographic Classification 223
Russian Trade and Bibliographic Classification 614
Russian Trade and Bibliographic Classification 6135
BISAK SCI004000 Astronomy
BISAK SCI005000 Physics / Astrophysics
Language:
English
Keywords:
Galaxy: kinematics and dynamics
Abstract (English):
We studied the model of the Galaxy that reproduces the observed median velocity distribution derived from Gaia DR3 data along the Galactocentric distance, $R$. The model profiles of radial velocity, $V_R$, demonstrate an increase with a period of $P = 2.1 \pm{0.1}$ Gyr and form humps at $R = $ 6-7 kpc. The average amplitude of variation in the radial velocity is $A = 1.76 \pm{0.20}\, \rm km\, s^{-1}$. The humps are supported by orbits changing orientation relative to the major axis of the bar within the range of $[-45, \;45]$$^{\circ}$. The median period of variation in the angular momentum of hump-supporting orbits is $P = 1.85 \pm{0.17}$ Gyr, and 71.6 % of them support ring $R_2$. The observed profile does not show any humps. In the model profile, humps disappear during the times $2.5 \pm{0.3}$ and $4.5 \pm{0.5}$ Gyr, indicating that the age of the Galactic bar must be close to one of these values. The model disk forms outer resonance rings $R_1$ and $R_2$, which demonstrate periodic changes in their morphology with a period of $P = 2.0\pm{0.1}$ Gyr, supported by orbits trapped by the Outer Lindblad Resonance.
We studied the model of the Galaxy that reproduces the observed median velocity distribution derived from Gaia DR3 data along the Galactocentric distance, $R$. The model profiles of radial velocity, $V_R$, demonstrate an increase with a period of $P = 2.1 \pm{0.1}$ Gyr and form humps at $R = $ 6-7 kpc. The average amplitude of variation in the radial velocity is $A = 1.76 \pm{0.20}\, \rm km\, s^{-1}$. The humps are supported by orbits changing orientation relative to the major axis of the bar within the range of $[-45, \;45]$$^{\circ}$. The median period of variation in the angular momentum of hump-supporting orbits is $P = 1.85 \pm{0.17}$ Gyr, and 71.6 % of them support ring $R_2$. The observed profile does not show any humps. In the model profile, humps disappear during the times $2.5 \pm{0.3}$ and $4.5 \pm{0.5}$ Gyr, indicating that the age of the Galactic bar must be close to one of these values. The model disk forms outer resonance rings $R_1$ and $R_2$, which demonstrate periodic changes in their morphology with a period of $P = 2.0\pm{0.1}$ Gyr, supported by orbits trapped by the Outer Lindblad Resonance.
Keywords:
Galaxy: kinematics and dynamics
Galaxy: kinematics and dynamics
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