Is the vorticity vector of the Galaxy perpendicular to the Galactic plane? II - Kinematics of the Galactic warp

Miyamoto, M.; Sôma, Mitsuru; Yoshizawa, M.

doi:10.1086/116592

Cited by 32 publications

(15 citation statements)

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“…), T < 4.64 Gyr (95.4% C.L.). Our results are equivalent to a rotation of the rings around the line of nodes with an angular velocity oḟ result of +4 km s −1 /kpc given by Miyamoto et al (1993) or Miyamoto & Zhu (1998) at short distances from the Sun, but it is more similar to the result of −4 km s −1 /kpc by Bobylev (2010), who also used RGCs. Bobylev (2013) obtained with Cepheids a value of −15 km s −1 /kpc, which is different from our result.…”

Section: We Can Derive Some Information Of the Warp Kinematicssupporting

confidence: 69%

Vertical velocities from proper motions of red clump giants

López-Corredoira

Abedi

Garzón

et al. 2014

A&A

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Aims. We derive the vertical velocities of disk stars in the range of Galactocentric radii of R = 5−16 kpc within 2 kpc in height from the Galactic plane. This kinematic information is connected to dynamical aspects in the formation and evolution of the Milky Way, such as the passage of satellites and vertical resonance and determines whether the warp is a long-lived or a transient feature. Methods. We used the PPMXL survey, which contains the USNO-B1 proper motions catalog cross-correlated with the astrometry and near-infrared photometry of the 2MASS point source catalog. To improve the accuracy of the proper motions, the systematic shifts from zero were calculated by using the average proper motions of quasars in this PPMXL survey, and we applied the corresponding correction to the proper motions of the whole survey, which reduces the systematic error. From the color-magnitude diagram K versus (J − K) we selected the standard candles corresponding to red clump giants and used the information of their proper motions to build a map of the vertical motions of our Galaxy. We derived the kinematics of the warp both analytically and through a particle simulation to fit these data. Complementarily, we also carried out the same analysis with red clump giants spectroscopically selected with APOGEE data, and we predict the improvements in accuracy that will be reached with future Gaia data. Results. A simple model of warp with the height of the disk z w (R, φ) = γ(R − R ) sin(φ − φ w ) fits the vertical motions ifγ/γ = −34 ± 17 Gyr −1 ; the contribution toγ comes from the southern warp and is negligible in the north. If we assume this 2σ detection to be real, the period of this oscillation is shorter than 0.43 Gyr at 68.3% C.L. and shorter than 4.64 Gyr at 95.4% C.L., which excludes with high confidence the slow variations (periods longer than 5 Gyr) that correspond to long-lived features. Our particle simulation also indicates a probable abrupt decrease of the warp amplitude in a time of about one hundred Myr. Conclusions. The vertical motion in the warp apparently indicates that the main S-shaped structure of the warp is a long-lived feature, whereas the perturbation that produces an irregularity in the southern part is most likely a transient phenomenon. But we need higher accuracy in the systematic errors of proper motions to confirm this tentative detection of vertical motion in the outer disk. With the use of the Gaia end-of-mission products together with spectroscopically classified red clump giants, the precision in vertical motions can be increased by an order of magnitude at least.

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Section: We Can Derive Some Information Of the Warp Kinematicssupporting

confidence: 69%

Vertical velocities from proper motions of red clump giants

López-Corredoira

Abedi

Garzón

et al. 2014

A&A

View full text Add to dashboard Cite

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“…and an R 0 less than 8 kpc (Brand & Blitz 1993;Honma & Sofue 1996;Reid 1993;Miyamoto et al 1993;Dambis et al 1995). Recently, Olling & Merrifield (1998), from mass model calculations, have concluded that a consistent picture emerges only when considering R 0 = 7.1 ± 0.4 kpc and θ 0 = 184 ± 8 km s −1 .…”

Section: The Kinematic Distancesmentioning

confidence: 99%

Star-forming complexes and the spiral structure of our Galaxy

Russeil¹

2002

A&A

460

598

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Abstract.We have carried out a multiwavelength study of the plane of our Galaxy in order to establish a star-forming-complex catalogue which is as complete as possible. Features observed include Hα, H109α, CO, the radio continuum and absorption lines. For each complex we have determined the position, the systemic velocity, the kinematic distance and, when possible, the stellar distance and the corresponding uncertainties. All of these parameters were determined as homogeneously as possible, in particular all the stellar distances have been (re)calculated with the same calibration and the kinematic distances with the same mean Galactic rotation curve. Through the complexes with stellar distance determination, a rotation curve has been fitted. It is in good agreement with the one of Brand & Blitz (1993). We also investigated the residual velocities relative to the circular rotation model. We find that departures exist over large areas of the arms, with different values from one arm to another. From our data and in good agreement with previous studies, the Galactic warp is observed. It does not seem correlated with the departures from circular rotation. Finally, as segment-like features are noted from the complexes' distribution, we tried to find if they are indicative of a larger underlying structure. Then, we attempted to interpret the complexes' distribution in terms of spiral structure by fitting models with two, three and four logarithmic spiral arms. The four-arm model seems more appropriate to represent the grand design of our Galaxy. In this model the Norma arm and the external arm appear as being the two extremities of a single arm called the Norma-Cygnus arm. The new data and fitted model confirm the four-segment model of Georgelin & Georgelin (1976), clarifying the arms' design and extension and doubling their known length.

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“…Both effects need explanation. For this purpose consider the contribution of the Ω 1 and M www.an-journal.org Now, in the galactocentric cylindrical coordinate system we have (Miyamoto et al 1993)…”

Section: The Vertical Gradient Of the Galaxy's Rotational Velocitymentioning

confidence: 99%

UCAC4: Stellar kinematics with vector spherical functions

Vityazev¹,

Tsvetkov²

2013

Astron Nachr

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We present a method of kinematic analysis of proper motions by vector spherical functions, and the results of its application to astrometric data. The sets of vector spherical functions which are orthonormal on a full sphere as well as on a latitude zone are constructed. Decomposition of the proper motions into a set of such functions allows model-independent study of stellar kinematics. If needed, the parameters of the standard (say, Ogorodnikov-Milne) model may be derived from the coefficients of the decomposition. In contrast to the commonly used least squares estimation of the model's parameters, vector spherical functions identify all systematic components of the velocity field (no matter, whether they are incorporated into the model or not) and give us a possibility to test whether the data are compatible with the model. In this paper, we apply this technique for the first time to the proper motions from the UCAC4 catalog for stars in the 11 to 16 magnitude range. We derive all-sky solutions and the solutions based on stars in the northern and southern Galactic hemispheres. The all-sky solution provide evidence for noticeable magnitude-dependent trends in the coordinates of the solar motion apex, Oort constants, angular speed of the local Galactic rotation, and the slope of the local rotation velocity curve as we go from bright to faint stars. Furthermore, our all-sky vector spherical function analysis identified strong and reliable extramodel harmonics, whereas the solutions for the northern and southern hemisphere indicate sign reversals for some of the Ogorodnikov-Milne parameters. We show that both effects appear simultaneously and can be explained by the slowdown of Galactic rotation with increasing distance from the main Galactic plane. We estimate the absolute value of the vertical gradient of the Galactic rotational velocity to be ∼ 40 km s −1 kpc −1 .

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Is the vorticity vector of the Galaxy perpendicular to the Galactic plane? II - Kinematics of the Galactic warp

Cited by 32 publications

References 0 publications

Vertical velocities from proper motions of red clump giants

Vertical velocities from proper motions of red clump giants

Star-forming complexes and the spiral structure of our Galaxy

UCAC4: Stellar kinematics with vector spherical functions

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