Estimation of the Tilt of the Stellar Velocity Ellipsoid from RAVE and Implications for Mass Models

Abstract

We present a measure of the inclination of the velocity ellipsoid at 1 kpc below the Galactic plane using a sample of red clump giants from the RAVE DR2 release. We find that the velocity ellipsoid is tilted towards the Galactic plane with an inclination of 7.3 +/-1.8 degree. We compare this value to computed inclinations for two mass models of the Milky Way. We find that our measurement is consistent with a short scale length of the stellar disc (Rd ~2 kpc) if the dark halo is oblate or with a long scale length (Rd~3 kpc) if the dark halo is prolate. Once combined with independent constraints on the flattening of the halo, our measurement suggests that the scale length is approximately halfway between these two extreme values, with a preferred range [2.5-2.7] kpc for a nearly spherical halo. Nevertheless, no model can be clearly ruled out. With the continuation of the RAVE survey, it will be possible to provide a strong constraint on the mass distribution of the Milky Way using refined measurements of the orientation of the velocity ellipsoid.

arXiv commentAccepted for publication in MNRAS, 10 pages, 9 figures, 2 tables

References in corpus (36)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The Radial Velocity Experiment (RAVE): first data release
• The Field of Streams: Sagittarius and its Siblings
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• The Radial Velocity Experiment (RAVE): Fifth Data Release
• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• Local kinematics of K and M giants from Coravel/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
• The RAdial Velocity Experiment (RAVE): Fourth data release
• Mass models of the Milky Way
• The Distribution of Nearby Stars in Velocity Space Inferred from Hipparcos Data
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails
• The extended tails of Palomar 5: A ten degree arc of globular cluster tidal debris
• The radial velocity dispersion profile of the Galactic halo: Constraining the density profile of the dark halo of the Milky Way
• The Radial Velocity Experiment (RAVE): second data release
• The local surface density of disc matter mapped by Hipparcos
• The Origin of the Bifurcation in the Sagittarius Stream
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: III. Constraints on the Flattening of the Galactic Halo
• Velocity trends in the debris of Sagittarius and the shape of the dark-matter halo of the Galaxy
• K-Band Calibration of the Red Clump Luminosity
• The stellar velocity distribution in the solar neighbourhood
• Detection of a 45 Degree Tidal Stream Associated with the Globular Cluster NGC 5466
• A 22 Degree Tidal Tail for Palomar 5
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• Luminous and Dark Matter in the Milky Way
• On the age heterogeneity of the Pleiades, Hyades and Sirius moving groups
• Vertical distribution of Galactic disk stars : II. The surface mass density in the Galactic plane
• Galactic kinematics with RAVE data: I. The distribution of stars towards the Galactic poles
• Is the sky falling? Searching for stellar streams in the local Milky Way disc in the CORAVEL and RAVE surveys
• The Virgo stellar over-density: Mapping the infall of the Sagittarius tidal stream onto the Milky Way disk
• Tidal streams in a MOND potential: constraints from Sagittarius
• Constraining Spiral Structure Parameters through Galactic Pencil-beam and Large-scale Radial Velocity Surveys
• Disentangling the Galaxy at low Galactic latitudes

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