The nearby spiral density-wave structure of the Galaxy: line-of-sight velocities of the Gaia DR2 OB stars

2021 ◽  
Vol 503 (1) ◽  
pp. 354-361
Author(s):  
Evgeny Griv ◽  
Michael Gedalin ◽  
Ing-Guey Jiang
Keyword(s):  
Density Wave ◽  
Wave Structure ◽  
Wave Theory ◽  
Solar Neighborhood ◽  
Line Of Sight ◽  
Density Waves ◽  
Ob Stars ◽  
Spiral Density Waves ◽  
The Galaxy ◽  
Gravity Disturbances

ABSTRACT Distances and line-of-sight velocities of 964 Gaia Data Release 2 (DR2) OB stars of Xu et al. within 3 kpc from the Sun and 500 pc from the Galactic mid-plane with accuracies of <50 per cent are selected. The data are used to find small systematic departures of velocities from the mean circular motion for the stars in the solar neighborhood due to the spiral compression-type (Lin–Shu-type) waves, or spiral density waves, e.g. those produced by real instabilities of spontaneous gravity disturbances, a central bar or a companion system. A key point of the study is that our results are consistent with the ones extracted from the asymptotic density-wave theory. Revised parameters of density waves in the solar vicinity of the Galaxy are also provided.

The nearby spiral density-wave structure of the Galaxy: line-of-sight velocities of the Gaia DR2 main-sequence A, F, G, and K stars

2020 ◽  
Vol 493 (2) ◽  
pp. 2111-2126
Author(s):  
Evgeny Griv ◽  
Michael Gedalin ◽  
I-Chun Shih ◽  
Li-Gang Hou ◽  
Ing-Guey Jiang
Keyword(s):  
Main Sequence ◽  
Density Wave ◽  
Wave Structure ◽  
Wave Pattern ◽  
Line Of Sight ◽  
The Sun ◽  
Density Waves ◽  
Spiral Density Waves ◽  
The Galaxy ◽  
Spiral Arm

ABSTRACT Distances and velocities of $\approx \!2400\, 000$ main-sequence A, F, G, and K stars are collected from the second data release of ESA's Gaia astrometric mission. This material is analysed to find evidence of radial and azimuthal systematic non-circular motions of stars in the solar neighbourhood on the assumption that the system is subject to spiral density waves (those produced by a spontaneous disturbance, a central bar, or an external companion), developing in the Galactic disc. Data analysis of line-of-sight velocities of $\approx \!1500\, 000$ stars selected within 2 kpc from the Sun and 500 pc from the Galactic mid-plane with distance accuracies of <10 per cent makes evident that a radial wavelength of the wave pattern is 1.1–1.6 kpc and a phase of the wave at the Sun’s location in the Galaxy is 55°–95°. Respectively, the Sun is situated at the inner edge of the nearest Orion spiral arm segment. Thus, the local Orion arm is a part of a predominant density-wave structure of the system. The spiral structure of the Galaxy has an oscillating nature corresponding to a concept of the Lin–Shu-type moderately growing in amplitude, tightly wound, and rigidly rotating density waves.

The nearby spiral density-wave structure of the Galaxy: line-of-sight and longitudinal velocities of 223 Cepheids

2016 ◽  
Vol 464 (4) ◽  
pp. 4495-4508 ◽  
Author(s):  
Evgeny Griv ◽  
Li-Gang Hou ◽  
Ing-Guey Jiang ◽  
Chow-Choong Ngeow
Keyword(s):  
Density Wave ◽  
Wave Structure ◽  
Line Of Sight ◽  
Spiral Density Wave ◽  
The Galaxy

The Lin–Shu type density–wave structure of the Galaxy: Line-of-sight velocities of selected 37354 RAVE DR5 stars

New Astronomy ◽  
2019 ◽  
Vol 66 ◽  
pp. 1-8 ◽  
Author(s):  
Evgeny Griv ◽  
Ing-Guey Jiang ◽  
Li-Gang Hou ◽  
Chow-Choong Ngeow
Keyword(s):  
Density Wave ◽  
Wave Structure ◽  
Line Of Sight ◽  
The Galaxy

The nearby spiral density-wave structure of the Galaxy: Line-of-sight and longitudinal velocities of 61 masers

2017 ◽  
Vol 338 (6) ◽  
pp. 729-739
Author(s):  
E. Griv ◽  
I.-G. Jiang ◽  
L.-G. Hou ◽  
C.-C. Ngeow
Keyword(s):  
Density Wave ◽  
Wave Structure ◽  
Line Of Sight ◽  
Spiral Density Wave ◽  
The Galaxy

scholarly journals Lifetime of density waves and classification of spirals

1979 ◽  
Vol 84 ◽  
pp. 155-156
Author(s):  
J. V. Feitzinger ◽  
Th. Schmidt-Kaler
Keyword(s):  
Density Wave ◽  
Wave Theory ◽  
Density Waves ◽  
Spiral Arms ◽  
Density Wave Theory

Checking the density-wave theory against observations of our own Galaxy has proven very difficult, as witnessed also at this Symposium. Less ambiguous results, however, are obtained for other galaxies. These results involve a) calculating convincing models for a sample of 25 fairly well observed spirals (Roberts et al. 1975) and b) locating the compression zones on the inner edges of the spiral arms.

The nearby spiral density–wave structure of the Galaxy

2017 ◽  
Vol 468 (3) ◽  
pp. 3361-3367 ◽  
Author(s):  
Evgeny Griv ◽  
Ing-Guey Jiang ◽  
Li-Gang Hou
Keyword(s):  
Density Wave ◽  
Wave Structure ◽  
Spiral Density Wave ◽  
The Galaxy

scholarly journals Interpretation of Observations of Spiral Structure in Terms of the Density Wave Theory

1974 ◽  
Vol 58 ◽  
pp. 399-412 ◽  
Author(s):  
Per Olof Lindblad
Keyword(s):  
Spiral Structure ◽  
Density Wave ◽  
Wave Theory ◽  
Density Waves ◽  
Density Wave Theory

A review is given of recent theoretical and observational work on the density wave theory of spiral structure. Emphasis is put on the kinematic picture, and the question whether modern observations reveal the existence of density waves is discussed.

scholarly journals Density waves and the viscous overstability in Saturn’s rings

2019 ◽  
Vol 623 ◽  
pp. A121 ◽  
Author(s):  
M. Lehmann ◽  
J. Schmidt ◽  
H. Salo
Keyword(s):  
Large Scale ◽  
Density Wave ◽  
Relative Magnitude ◽  
Density Waves ◽  
Scale Free ◽  
Short Scale ◽  
Spiral Density Waves ◽  
Saturn’S Rings ◽  
Saturn's Rings ◽  
Lindblad Resonance

This paper considers resonantly forced spiral density waves in a dense planetary ring that is close to the threshold for viscous overstability. We solved numerically the hydrodynamical equations for a dense thin disk in the vicinity of an inner Lindblad resonance with a perturbing satellite. Our numerical scheme is one-dimensional so that the spiral shape of a density wave is taken into account through a suitable approximation of the advective terms arising from the fluid orbital motion. This paper is a first attempt to model the co-existence of resonantly forced density waves and short-scale free overstable wavetrains as observed in Saturn’s rings, by conducting large-scale hydrodynamical integrations. These integrations reveal that the two wave types undergo complex interactions, not taken into account in existing models for the damping of density waves. In particular we found that, depending on the relative magnitude of both wave types, the presence of viscous overstability can lead to the damping of an unstable density wave and vice versa. The damping of the short-scale viscous overstability by a density wave was investigated further by employing a simplified model of an axisymmetric ring perturbed by a nearby Lindblad resonance. A linear hydrodynamic stability analysis as well as local N-body simulations of this model system were performed and support the results of our large-scale hydrodynamical integrations.

The spiral density-wave structure of our own Galaxy as traced by open clusters: Least-squares analysis of line-of-sight velocities

New Astronomy ◽  
2014 ◽  
Vol 29 ◽  
pp. 9-17 ◽  
Author(s):  
Evgeny Griv ◽  
Chien-Cheng Lin ◽  
Chow-Choong Ngeow ◽  
Ing-Guey Jiang
Keyword(s):  
Least Squares ◽  
Density Wave ◽  
Wave Structure ◽  
Open Clusters ◽  
Line Of Sight ◽  
Spiral Density Wave

scholarly journals Theoretical 21-cm line profiles: Comparison with observations

1970 ◽  
Vol 38 ◽  
pp. 391-396 ◽  
Author(s):  
C. Yuan
Keyword(s):  
Galactic Plane ◽  
Density Wave ◽  
Neutral Hydrogen ◽  
Wave Theory ◽  
Line Profiles ◽  
Spiral Pattern ◽  
The Galaxy ◽  
Density Wave Theory ◽  
Good Agreement

In order to make a direct comparison with observations of the 21-cm line of neutral hydrogen, theoretical profiles based on the ideas of the density-wave theory are constructed for a modified Schmidt model of the Galaxy and its theoretical spiral pattern. The comparison has covered galactic longitudes lII = 30° −330° with 10° intervals in the galactic plane. Good agreement is found in most of the above directions.

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