Evidence of a Metal-rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid

Soto, M.; Rich, R. Michael; Kuijken, Konrad

doi:10.1086/521098

Cited by 64 publications

(91 citation statements)

References 28 publications

(43 reference statements)

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“…The result of this increased sample has been consistent with the preliminary Zhao results (Soto et al 2007) showing a significant vertex deviation only for the metal rich stars. Moreover, the sample of K giants shows a remarkable agreement in l v with our own sample of turn-off and main sequence stars, where the angles found are −34 • ± 7 • and −43 • ± 4 • respectively.…”

Section: Discussionsupporting

confidence: 89%

3-dimensional kinematics in low foreground extinction windows of the Galactic bulge

Soto

Kuijken

Rich

2012

A&A

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Aims. The detailed structure of the Galactic bulge still remains uncertain. The strong difficulties of obtaining observations of stars in the Galactic bulge have hindered the acquisition of a kinematic representation for the inner kpc of the Milky Way. The observation of the 3-d kinematics in several low foreground extinction windows can solve this problem. Methods. We have developed a new technique, which combines precise stellar HST positions and proper motions with integral field spectroscopy, in order to obtain reliable 3-d stellar kinematics in crowded fields of the Galactic center.Results. In addition, we present results using the new techniques for six fields in our project. A significant vertex deviation has been found in some of the fields in agreement with previous determinations. This result confirms the presence of a stellar bar in the Galactic bulge.

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Section: Discussionsupporting

confidence: 89%

3-dimensional kinematics in low foreground extinction windows of the Galactic bulge

Soto

Kuijken

Rich

2012

A&A

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“…They found a significant vertex deviation (i.e., a triaxility signature) for the metal-rich population in their small proper motion-radial velocity combined sample. The same signature of triaxility was observed by Soto et al (2007), who combined Spaenhauer et al (1992) proper motions with Sadler et al (1996) and Terndrup et al (1995) radial velocities and metallicities to obtain a sample of ∼300 K giants with 3D kinematics and metallicities. More recently, the same triaxility signature related to two distinct populations, metal-rich and metal-poor, has been confirmed using high-resolution spectra by Babusiaux et al (2010) and Hill et al (2011).…”

Section: Introductionsupporting

confidence: 67%

Proper motions for HST observations in three off-axis bulge fields

Soto

Zeballos

Kuijken

et al. 2014

A&A

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Aims. This is the second in a series of papers that attempt to unveil the kinematic structure of the Galactic bulge through studying radial velocities and proper motions. We report here ∼15 000 new proper motions for three low foreground-extinction off-axis fields of the Galactic bulge. Methods. Proper motions were derived from a combination of Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) and Advanced Camera for Surveys (ACS) images taken 8 and 9 years apart, and they reach accuracies better than 0.9 mas yr −1 for more than ∼10 000 objects with magnitudes F814W ≤ 24. Results. The proper motion distributions in these fields are similar to those of Galactic minor axis bulge fields. We observe the rotation of main sequence stars below the turn-off within the Galactic bulge, as in the minor axis fields. Conclusions. Our stellar proper motions measurements show a significant bulge rotation for fields as far from the Galactic plane as b −8 • .

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“…From stellar kinematics studies, we learn that the velocity ellipsoid of moderate metal-rich ([Fe/H] > −0.5 dex), non α-enhanced stars shows a vertex deviation consistent with those stars supporting a bar-like structure (Zhao et al 1994;Soto et al 2007;Babusiaux et al 2010;Hill et al 2011). However, such studies also reveal that the most metal-poor, α-enhanced stars are not part of this elongated structure, since they have velocity dispersions that are consistent with a kinematically hotter component (Babusiaux et al 2010;Hill et al 2011;Uttenthaler et al 2012;Ness et al 2013b;Rojas-Arriagada et al 2014).…”

Section: Introductionmentioning

confidence: 64%

Why the Milky Way’s bulge is not only a bar formed from a cold thin disk

Matteo

Gómez

Haywood

et al. 2015

A&A

104

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By analyzing an N-body simulation of a bulge formed simply via a bar instability mechanism operating on a kinematically cold stellar disk, and by comparing the results of this analysis with the structural and kinematic properties of the main stellar populations of the Milky Way bulge, we conclude that the bulge of our Galaxy is not a pure stellar bar formed from a pre-existing thin stellar disk, as some studies have recently suggested. On the basis of several arguments emphasized in this paper, we propose that the bulge population that, in the Milky Way, is observed to not be part of the peanut structure corresponds to the old Galactic thick disk, thus implying that the Milky Way is a pure thin+thick disk galaxy, with only a possible limited contribution by a classical bulge.

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Evidence of a Metal-rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid

Cited by 64 publications

References 28 publications

3-dimensional kinematics in low foreground extinction windows of the Galactic bulge

3-dimensional kinematics in low foreground extinction windows of the Galactic bulge

Proper motions for HST observations in three off-axis bulge fields

Why the Milky Way’s bulge is not only a bar formed from a cold thin disk

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