The Southern Proper Motion Program. Iv. The Spm4 Catalog

Girard, Terrence M.; Altena, W. F. van; Zacharias, N.; Vieira, K.; Casetti-Dinescu, Dana I.; Castillo, Danilo J.; Herrera, David; Lee, Young Sun; Beers, Timothy C.; Monet, D. G.; López, Carlos

doi:10.1088/0004-6256/142/1/15

Cited by 138 publications

(126 citation statements)

References 39 publications

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“…The Tycho-Gaia Astrometric Solution (TGAS, Lindegren et al 2016) from the Gaia data release 1 provides trigonometric parallaxes and proper motions for 203 stars in our sample. To access more proper motion data, we also searched for this information in the PPMXL (Roeser et al 2010), UCAC4 (Zacharias et al 2012) and SPM4 (Girard et al 2011) catalogs. Doing so, we find proper motions for 368 stars of the sample.…”

Section: Appendix A: Ad Hoc Force To Account For Type II Migrationmentioning

confidence: 99%

Origin of the wide-orbit circumbinary giant planet HD 106906

Rodet

Beust

Bonnefoy

et al. 2017

A&A

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Context. A giant planet has been recently resolved at a projected distance of 730 au from the tight pair of young (∼13 Myr) intermediate-mass stars HD 106906AB in the Lower Centaurus Crux (LCC) group. The stars are surrounded by a debris disk which displays a ring-like morphology and strong asymmetries at multiple scales. Aims. We aim to study the likelihood of a scenario where the planet formed closer to the stars in the disk, underwent inward diskinduced migration, and got scattered away by the binary star before being stabilized by a close encounter (fly-by). Methods. We performed semi-analytical calculations and numerical simulations (Swift_HJS package) to model the interactions between the planet and the two stars. We accounted for the migration as a simple force. We studied the LCC kinematics to set constraints on the local density of stars, and therefore on the fly-by likelihood. We performed N-body simulations to determine the effects of the planet trajectories (ejection and secular effects) onto the disk morphology. Results. The combination of the migration and mean-motion resonances with the binary star (often 1:6) can eject the planet. Nonetheless, we estimate that the fly-by hypothesis decreases the scenario probability to less than 10 −7 for a derived local density of stars of 0.11 stars/pc 3 . We show that the concomitant effect of the planet and stars trajectories induce spiral-features in the disk which may correspond to the observed asymmetries. Moreover, the present disk shape suggests that the planet is on an eccentric orbit. Conclusions. The scenario we explored is a natural hypothesis if the planet formed within a disk. Conversely, its low probability of occurrence and the fact that HD 106906 b shares some characteristics with other systems in Sco-Cen (e.g., HIP 78530, in terms of mass ratio and separation) may indicate an alternative formation pathway for those objects.

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Section: Appendix A: Ad Hoc Force To Account For Type II Migrationmentioning

confidence: 99%

Origin of the wide-orbit circumbinary giant planet HD 106906

Rodet

Beust

Bonnefoy

et al. 2017

A&A

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“…In order to further investigate the nature of our sample stars, we extracted their proper motions from two sources: the Southern Proper Motion Catalog 4 (SPM4; Girard et al 2011) and The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4; Zacharias et al 2013). As Fig.…”

Section: Kinematicsmentioning

confidence: 99%

Metal-poor stars towards the Galactic bulge: A population potpourri

Koch

McWilliam

Preston

et al. 2016

A&A

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We present a comprehensive chemical abundance analysis of five red giants and two horizontal branch (HB) stars towards the southern edge of the Galactic bulge, at (l, b) ∼ (0 • ,−11 • ). Based on high-resolution spectroscopy obtained with the Magellan/MIKE spectrograph, we derived up to 23 chemical element abundances and identify a mixed bag of stars, representing various populations in the central regions of the Galaxy. Although cosmological simulations predict that the inner Galaxy was host to the first stars in the Universe, we see no chemical evidence of the ensuing massive supernova explosions: all of our targets exhibit halo-like, solar [Sc/Fe] ratios, which is in contrast to the low values predicted from Population III nucleosynthesis. One of the targets is a CEMP-s star at [Fe/H] = −2.52 dex, and another target is a moderately metal-poor ([Fe/H] = −1.53 dex) CH star with strong enrichment in s-process elements (e.g., [Ba/Fe] = 1.35). These individuals provide the first contenders of these classes of stars towards the bulge. Four of the carbon-normal stars exhibit abundance patterns reminiscent of halo star across a metallicity range spanning −2.0 to −2.6 dex, i.e., enhanced α-elements and solar Fe-peak and neutron-capture elements, and the remaining one is a regular metal-rich bulge giant. The position, distance, and radial velocity of one of the metal-poor HB stars coincides with simulations of the old trailing arm of the disrupted Sagittarius dwarf galaxy. While their highly uncertain proper motions prohibit a clear kinematic separation, the stars' chemical abundances and distances suggest that these metal-poor candidates, albeit located towards the bulge, are not of the bulge, but rather inner halo stars on orbits that make them pass through the central regions. Thus, we caution similar claims of detections of metal-poor stars as true habitants of the bulge.

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“…We do not use proper motions, or stellar parameters that could in principle provide tighter constraints, but then one has to worry about the systematics introduced by their use. For example, in a recent kinematic analysis of RAVE stars, Williams et al (2013) found systematic differences between different proper-motion catalogs like PPMXL (Röser et al 2008), SPM4 (Girard et al 2011), and UCAC3 (Zacharias et al 2010). As for stellar parameters, although they are reliable, no pipeline can claim to be free of unknown systematics, especially when working with low signalto-noise ratio data.…”

Section: Rave Surveymentioning

confidence: 99%

Kinematic Modeling of the Milky Way Using the Rave and GCS Stellar Surveys

Sharma

Bland-Hawthorn

Binney

et al. 2014

ApJ

120

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We investigate the kinematic parameters of the Milky Way disk using the Radial Velocity Experiment (RAVE) and Geneva-Copenhagen Survey (GCS) stellar surveys. We do this by fitting a kinematic model to the data and taking the selection function of the data into account. For stars in the GCS we use all phase-space coordinates, but for RAVE stars we use only ( , b, v los ). Using the Markov Chain Monte Carlo technique, we investigate the full posterior distributions of the parameters given the data. We investigate the age-velocity dispersion relation for the three kinematic components (σ R , σ φ , σ z ), the radial dependence of the velocity dispersions, the solar peculiar motion (U , V , W ), the circular speed Θ 0 at the Sun, and the fall of mean azimuthal motion with height above the midplane. We confirm that the Besançon-style Gaussian model accurately fits the GCS data but fails to match the details of the more spatially extended RAVE survey. In particular, the Shu distribution function (DF) handles noncircular orbits more accurately and provides a better fit to the kinematic data. The Gaussian DF not only fits the data poorly but systematically underestimates the fall of velocity dispersion with radius. The radial scale length of the velocity dispersion profile of the thick disk was found to be smaller than that of the thin disk. We find that correlations exist between a number of parameters, which highlights the importance of doing joint fits. The large size of the RAVE survey allows us to get precise values for most parameters. However, large systematic uncertainties remain, especially in V and Θ 0 . We find that, for an extended sample of stars, Θ 0 is underestimated by as much as 10% if the vertical dependence of the mean azimuthal motion is neglected. Using a simple model for vertical dependence of kinematics, we find that it is possible to match the Sgr A* proper motion without any need for V being larger than that estimated locally by surveys like GCS.

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The Southern Proper Motion Program. Iv. The Spm4 Catalog

Cited by 138 publications

References 39 publications

Origin of the wide-orbit circumbinary giant planet HD 106906

Origin of the wide-orbit circumbinary giant planet HD 106906

Metal-poor stars towards the Galactic bulge: A population potpourri

Kinematic Modeling of the Milky Way Using the Rave and GCS Stellar Surveys

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