Gaia DR1 Evidence of Disrupting the Perseus Arm

Baba, Junichi; Kawata, Daisuke; Matsunaga, Noriyuki; Grand, Robert J. J.; Hunt, Jason A. S.

doi:10.3847/2041-8213/aaa839

Cited by 35 publications

(36 citation statements)

References 46 publications

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“…The location of the Perseus arm coincides with high density clouds in between our predicted two dashed lines. This is in agreement with the recent finding of Baba et al (2018) which uses data from Gaia DR1 concluding that the Perseus arm is being disrupted.…”

Section: Galactic Dust Mapsupporting

confidence: 93%

Detection of the Milky Way spiral arms in dust from 3D mapping

Kh.

Bailer‐Jones

Hogg

et al. 2018

A&A

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Large stellar surveys are sensitive to interstellar dust through the effects of reddening. Using extinctions measured from photometry and spectroscopy, together with three-dimensional (3D) positions of individual stars, it is possible to construct a three-dimensional dust map. We present the first continuous map of the dust distribution in the Galactic disk out to 7 kpc within 100 pc of the Galactic midplane, using red clump and giant stars from SDSS APOGEE DR14. We use a non-parametric method based on Gaussian Processes to map the dust density, which is the local property of the ISM rather than an integrated quantity. This method models the dust correlation between points in 3D space and can capture arbitrary variations, unconstrained by a pre-specified functional form. This produces a continuous map without line-of-sight artefacts. Our resulting map traces some features of the local Galactic spiral arms, even though the model contains no prior suggestion of spiral arms, nor any underlying model for the Galactic structure. This is the first time that such evident arm structures have been captured by a dust density map in the Milky Way. Our resulting map also traces some of the known giant molecular clouds in the Galaxy and puts some constraints on their distances, some of which were hitherto relatively uncertain.

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Section: Galactic Dust Mapsupporting

confidence: 93%

Detection of the Milky Way spiral arms in dust from 3D mapping

Kh.

Bailer‐Jones

Hogg

et al. 2018

A&A

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“…Thus, they are the result of perturbations induced by current spiral structures according to Siebert et al (2012). However, it is noted that they assume a steady spiral structure in their simulation, while the origin of the spiral structures is far from clear (Baba et al 2018;Tchernyshyov et al 2018;Sellwood et al 2018). Therefore, our results may not clearly exclude the perturbation of spiral arms originated from other mechanism but only rule out a steady density wave spiral structure.…”

Section: Discussionmentioning

confidence: 97%

Ripple Patterns in In-plane Velocities of OB Stars from LAMOST and Gaia

Cheng

Liu

Mao

et al. 2019

ApJL

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With about 12 000 OB type stars selected from the LAMOST and Gaia survey, we study their 3 dimensional velocity distribution over the range of galactocentric radius from 6 to 15 kpc in the Galactic disk plane. A clear ripple pattern in the radial velocity (V R ) map is shown. The median V R reaches −8 km s −1 at R ∼ 9 kpc, then increases to ∼ 0 km s −1 at R ∼ 12 kpc, and later declines to below −10 km s −1 beyond R ∼ 13 kpc. The median azimuthal velocity (V φ ) map shows a similar pattern but has roughly 1/4 phase difference with the radial velocity. Although the ripple of negative V R at ∼ 9 kpc extends to about 40 • in the azimuth angle, it does not align with either the Local or the Perseus spiral arm. Moreover, the farther ripple beyond 13 kpc does not match the Outer spiral arm either. This indicates that the non-axisymmetric kinematic features are not induced by perturbations of known spiral structures. The central rotating bar can not lead to such patterns in the outer disk either. External perturbation of a dwarf galaxy or a dark matter sub-halo can induce such patterns but requires more evidence from both observations and simulations. The V φ map in the Z-V Z plane of the OB stars is also investigated. Despite asymmetry to some degree, no spiral pattern is found. This is reasonable since most of the OB stars have ages much younger than 100 Myrs, which is smaller than one orbital period around the Galactic center.

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“…Hunt et al (2018) show that ridges in the same stellar velocity distribution resemble predictions from the dynamic model. An analysis of Cepheid velocities based on Gaia DR1 data by Baba et al (2018) found that the Perseus arm is likely to be a dynamic arm in the dissipation phase.…”

Section: Discussionmentioning

confidence: 99%

Kinetic Tomography. II. A Second Method for Mapping the Velocity Field of the Milky Way Interstellar Medium and a Comparison with Spiral Structure Models

Tchernyshyov

Peek

Zasowski

2018

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In this work, we derive a spatially resolved map of the line-of-sight velocity of the interstellar medium and use it, along with a second map of line-of-sight velocity from Paper I of this series, to determine the nature of gaseous spiral structure in the Milky Way. This map is derived from measurements of the 1.527 µm diffuse interstellar band (DIB) in stellar spectra from the APOGEE survey and covers the nearest 4-5 kpc of the Northern Galactic plane. We cross-check this new DIB-based line-of-sight velocity map with the map derived in Paper I and find that they agree. We then compare these maps with line-of-sight velocity maps derived from simulations of quasi-stationary density wave spiral structure and dynamic, or material, spiral structure in a Milky Way-like galaxy. While none of the maps derived from these simulations is an exact match to the measured velocity field of the Milky Way, the measurements are more consistent with simulations of dynamic spiral structure. In the dynamic spiral structure simulation that best matches the measurements, the Perseus spiral arm is being disrupted.

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Gaia DR1 Evidence of Disrupting the Perseus Arm

Cited by 35 publications

References 46 publications

Detection of the Milky Way spiral arms in dust from 3D mapping

Detection of the Milky Way spiral arms in dust from 3D mapping

Ripple Patterns in In-plane Velocities of OB Stars from LAMOST and Gaia

Kinetic Tomography. II. A Second Method for Mapping the Velocity Field of the Milky Way Interstellar Medium and a Comparison with Spiral Structure Models

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