Distance determination for RAVE stars using stellar models

Zwitter, T.; Matijevič, G.; Breddels, M. A.; Smith, M. C.; Helmi, Amina; Munari, U.; Bienaymé, O.; Binney, James; Bland-Hawthorn, Joss; Boeche, C.; Brown, A. G. A.; Campbell, Randy; Freeman, K. C.; Fulbright, Jon P.; Gibson, Brad K.; Gilmore, G.; Grebel, Eva K.; Navarro, Julio F.; Parker, Quentin A.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Steinmetz, Matthias; Watson, Fred; Williams, M.; Wyse, Rosemary F. Ġ.

doi:10.1051/0004-6361/201014922

Cited by 89 publications

(185 citation statements)

References 34 publications

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“…S07 showed via re-observations that the velocity measurement is reliable, however, the star did not get a distance estimate from Binney et al (2013). Zwitter et al (2010) estimate a distance of 9.4 kpc, which owing to its angular position (l, b) = (344.6 • , 31.4 • ), would place the star behind and above the Galactic center. The star thus clearly violates the assumption by S07 to deal with a locally confined stellar sample and potentially leads to an overestimate of the escape speed.…”

Section: Sample Selectionmentioning

confidence: 99%

The RAVE survey: the Galactic escape speed and the mass of the Milky Way

Piffl

Scannapieco

Binney³

et al. 2014

A&A

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We made new estimates of the Galactic escape speed at various Galactocentric radii using the latest data release of the RAdial Velocity Experiment (RAVE DR4). Compared to previous studies we have a database that is larger by a factor of 10, as well as reliable distance estimates for almost all stars. Our analysis is based on statistical analysis of a rigorously selected sample of 90 highvelocity halo stars from RAVE and a previously published data set. We calibrated and extensively tested our method using a suite of cosmological simulations of the formation of Milky Way-sized galaxies. Our best estimate of the local Galactic escape speed, which we define as the minimum speed required to reach three virial radii R 340 , is 533 +54 −41 km s −1 (90% confidence), with an additional 4% systematic uncertainty, where R 340 is the Galactocentric radius encompassing a mean overdensity of 340 times the critical density for closure in the Universe. From the escape speed we further derived estimates of the mass of the Galaxy using a simple mass model with two options for the mass profile of the dark matter halo: an unaltered and an adiabatically contracted Navarro, Frenk & White (NFW) sphere. If we fix the local circular velocity, the latter profile yields a significantly higher mass than the uncontracted halo, but if we instead use the statistics for halo concentration parameters in large cosmological simulations as a constraint, we find very similar masses for both models. Our best estimate for M 340 , the mass interior to R 340 (dark matter and baryons), is 1.3 +0.4 −0.3 × 10 12 M (corresponds to M 200 = 1.6 +0.5 −0.4 × 10 12 M ). This estimate is in good agreement with recently published, independent mass estimates based on the kinematics of more distant halo stars and the satellite galaxy Leo I.

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Section: Sample Selectionmentioning

confidence: 99%

The RAVE survey: the Galactic escape speed and the mass of the Milky Way

Piffl

Scannapieco

Binney³

et al. 2014

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“…With such errors we are confident that we can use these orbital parameters to distinguish between thin-and thick-disc stars, with only moderate contamination. During the preparation of this manuscript we used four different versions of distance estimations (two preliminary and one definitive, following the methods of Zwitter et al 2010;and A19, page 4 of 13 Binney et al, in prep. ) and two different chemical catalogue versions (DR3 by Siebert et al 2011;and DR4 by Kordopatis et al, in prep.…”

Section: Orbital Parametersmentioning

confidence: 99%

The relation between chemical abundances and kinematics of the Galactic disc with RAVE

Boeche

Chiappini

Minchev

et al. 2013

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Aims. We study the relations between stellar kinematics and chemical abundances of a large sample of RAVE giants in search of the selection criteria needed for disentangling different Galactic stellar populations, such as thin disc, thick disc and halo. A direct comparison between the chemo-kinematic relations obtained with our medium spectroscopic resolution data and those obtained from a high-resolution sample is carried out with the aim of testing the robustness of the RAVE data. Methods. We selected a sample of 2167 giant stars with signal-to-noise per spectral measurements above 75 from the RAVE chemical catalogue and followed the analysis performed by Gratton and colleagues on 150 subdwarf stars spectroscopically observed at high resolution. We then used a larger sample of 9131 giants (with signal-to-noise above 60) to investigate the chemo-kinematical characteristics of our stars by grouping them into nine subsamples with common eccentricity (e) and maximum distance achieved above the Galactic plane (Z max ). Results. The RAVE kinematical and chemical data proved to be reliable by reproducing the results by Gratton et al. obtained with high-resolution spectroscopic data. We successfully identified three stellar populations that could be associated with the Galactic thin disc, a dissipative component composed mostly of thick-disc stars, as well as a component comprised of halo stars (presence of debris stars cannot be excluded). Our analysis, based on the e-Z max plane combined with additional orbital parameters and chemical information, provides an alternative way of identifying different populations of stars. In addition to extracting canonical thick-and thin-disc samples, we find a group of stars in the Galactic plane (Z max < 1 kpc and 0.4 < e < 0.6) that show homogeneous kinematics but differ in their chemical properties. We interpret this as a clear sign that some of these stars have experienced the effects of heating and/or radial migration, which have modified their original orbits. The accretion origin of such stars cannot be excluded.

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“…In the context of stellar distances, a series of papers with increasing levels of sophistication has been presented by the RAVE collaboration Zwitter et al 2010;Burnett & Binney 2010). Burnett & Binney (2010) make use of a comprehensive set of measured parameters and their estimated uncertainties to infer, for each star, the probability distribution that a set of chosen stellar models generate the data.…”

Section: Introductionmentioning

confidence: 99%

Spectro-photometric distances to stars: A general purpose Bayesian approach

Santiago

Brauer

Anders

et al. 2015

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108

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Context. Determining distances to individual field stars is a necessary step towards mapping Galactic structure and determining spatial variations in the chemo-dynamical properties of stellar populations in the Milky Way. Aims. In order to provide stellar distance estimates for various spectroscopic surveys, we have developed a code that estimates distances to stars using measured spectroscopic and photometric quantities. We employ a Bayesian approach to build the probability distribution function over stellar evolutionary models given these data, delivering estimates of model parameters (including distances) for each star individually. Our method provides several alternative distance estimates for each star in the output, along with their associated uncertainties. This facilitates the use of our method even in the absence of some measurements. Methods. The code was first tested on simulations, successfully recovering input distances to mock stars with 1% bias. We found the uncertainties scale with the uncertainties in the adopted spectro-photometric parameters. The method-intrinsic random distance uncertainties for typical spectroscopic survey measurements amount to around 10% for dwarf stars and 20% for giants, and are most sensitive to the quality of log g measurements. Results. The code was then validated by comparing our distance estimates to parallax measurements from the H mission for nearby stars (<300 pc), to asteroseismic distances of CoRoT red giant stars, and to known distances of well-studied open and globular clusters. The photometric data of these reference samples cover both optical and infrared wavelengths. The spectroscopic parameters are also based on spectra taken at various wavelengths, with varying spectral coverage and resolution: the Sloan Digital Sky Survey programs SEGUE and APOGEE, as well as various ESO instruments. Conclusions. External comparisons confirm that our distances are subject to very small systematic biases with respect to the fundamental H scale (+0.4% for dwarfs, and +1.6% for giants). The typical random distance scatter is 18% for dwarfs, and 26% for giants. For the CoRoT-APOGEE sample, which spans Galactocentric distances of 4−14 kpc, the typical random distance scatter is 15% both for the nearby and farther data. Our distances are systematically larger than the CoRoT distances by about +9%, which can mostly be attributed to the different choice of priors. The comparison to known distances of star clusters from SEGUE and APOGEE has led to significant systematic differences for many cluster stars, but with opposite signs and substantial scatter. Finally, we tested our distances against those previously determined for a high-quality sample of giant stars from the RAVE survey, again finding a small systematic trend of +5% and an rms scatter of 30%. Efforts are underway to provide our code to the community by running it on a public server.

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Distance determination for RAVE stars using stellar models

Cited by 89 publications

References 34 publications

The RAVE survey: the Galactic escape speed and the mass of the Milky Way

The RAVE survey: the Galactic escape speed and the mass of the Milky Way

The relation between chemical abundances and kinematics of the Galactic disc with RAVE

Spectro-photometric distances to stars: A general purpose Bayesian approach

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