Calculation of the local standard of rest from 20574 local stars in the New Hipparcos Reduction with known radial velocities

Francis, Charles; Anderson, Erik

doi:10.1016/j.newast.2009.03.004

Cited by 63 publications

(66 citation statements)

References 48 publications

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“…According to these parameters, Reid et al (2009b) analyzed the parallax measurements toward 18 massive star forming regions, and they found a velocity difference of ∼15 km s −1 in rotation, which may be induced by an erroneous value of V . Higher values of V = 12.24−14.6 km s −1 are also suggested by some recent studies (e.g., Francis & Anderson 2009;Schönrich et al 2010;Coşkunoǧlu et al 2011;Reid et al 2014). Based on the solar motion parameters given by Schönrich et al (2010), Brunthaler et al (2011) reanalyzed the trigonometric parallax data of massive star forming regions, and found the peculiar rotation velocity of ∼8 ± 2 km s −1 .…”

Section: Fundamental Parameter R 0 θ 0 and Solar Motionssupporting

confidence: 79%

The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

228

233

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Context. The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7 GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. The distances for many of them have been determined in the literature with trigonometric, photometric, and/or kinematic methods. Aims. We update the catalogs of Galactic HII regions, GMCs, and 6.7 GHz methanol masers, and then outline the spiral structure of the Milky Way. Methods. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7 GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, R 0 = 8.5 kpc and Θ 0 = 220 km s −1 , and the most recent updated values of R 0 = 8.3 kpc and Θ 0 = 239 km s −1 , after velocities of tracers are modified with the adopted solar motions. With the weight factors based on the excitation parameters of HII regions or the masses of GMCs, we get the distributions of these spiral tracers.Results. The distribution of tracers shows at least four segments of arms in the first Galactic quadrant, and three segments in the fourth quadrant. The Perseus Arm and the Local Arm are also delineated by many bright HII regions. The arm segments traced by massive star forming regions and GMCs are able to match the HI arms in the outer Galaxy. We found that the models of three-arm and four-arm logarithmic spirals are able to connect most spiral tracers. A model of polynomial-logarithmic spirals is also proposed, which not only delineates the tracer distribution, but also matches the observed tangential directions.

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Section: Fundamental Parameter R 0 θ 0 and Solar Motionssupporting

confidence: 79%

The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

228

233

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“…At the other extreme, V value based on nearby M dwarfs is around 20 km s −1 (Reid et al 2009;Fuchs et al 2009;Bond et al 2010;Bochanski et al 2011). The interim values are typically in the range 11-14 km s −1 (see, e.g., Francis & Anderson 2009;Schönrich et al 2010;Coşkunoǧlu et al 2011). In agreement with the latter values is also an estimate by Bobylev & Bajkova (2010) based on known masers.…”

Section: Sun's Velocity With Respect To the Lsrmentioning

confidence: 98%

Radial velocities of K–M dwarfs and local stellar kinematics

Sperauskas

Bartasiute

Boyle

et al. 2016

A&A

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Aims. The goal of this paper is to present complete radial-velocity data for the spectroscopically selected McCormick sample of nearby K-M dwarfs and, based on these and supplementary data, to determine the space-velocity distributions of late-type stars in the solar neighborhood. Methods. We analyzed nearly 3300 measurements of radial velocities for 1049 K-M dwarfs, that we obtained during the past decade with a CORAVEL-type instrument, with a primary emphasis on detecting and eliminating from kinematic calculations the spectroscopic binaries and binary candidates. Combining radial-velocity data with Hipparcos/Tycho-2 astrometry we calculated the space-velocity components and parameters of the galactic orbits in a three-component model potential for the stars in the sample, that we use for kinematical analysis and for the identification of possible candidate members of nearby stellar kinematic groups. Results. We present the catalog of our observations of radial velocities for 959 stars which are not suspected of velocity variability, along with the catalog of U, V, W velocities and Galactic orbital parameters for a total of 1088 K-M stars which are used in the present kinematic analysis. Of these, 146 stars were identified as possible candidate members of the known nearby kinematic groups and suspected subgroups. The distributions of space-velocity components, orbital eccentricities, and maximum distances from the Galactic plane are consistent with the presence of young, intermediate-age and old populations of the thin disk and a small fraction (∼3%) of stars with the thick disk kinematics. The kinematic structure gives evidence that the bulk of K-M type stars in the immediate solar vicinity represents a dynamically relaxed stellar population. The star MCC 869 is found to be on a retrograde Galactic orbit (V = −262 km s −1 ) of low inclination (4 • ) and can be a member of stellar stream of some dissolved structure. The Sun's velocity with respect to the Local Standard of Rest, derived from the distributions of space-velocity components, is (U , V , W ) = (9.0 ± 1.4, 13.1 ± 0.6, 7.2 ± 0.8) km s −1 . The radial solar motion derived via the Strömberg's relation, V = 14.2 ± 0.8 km s −1 , agrees within the errors with the value obtained directly from the V distribution of stars on nearly circular orbits.

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“…Correction for a solar motion of (+7.5, +13.5, +6.8) km s −1 with respect to the LSR was adopted from Francis & Anderson (2009). The resulting values of U LSR , V LSR , and W LSR are given in Tables 3 and 4.…”

Section: Kinematicsmentioning

confidence: 99%

Two distinct halo populations in the solar neighborhood

Nissen¹,

Schuster²

2010

A&A

547

121

835

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Aims. Precise abundance ratios are determined for 94 dwarf stars with 5200 < T eff < 6300 K, −1.6 < [Fe/H] < −0.4, and distances D < ∼ 335 pc. Most of them have halo kinematics, but 16 thick-disk stars are included. Methods. Equivalent widths of atomic lines are measured from VLT/UVES and NOT/FIES spectra with resolutions R 55 000 and R 40 000, respectively. An LTE abundance analysis based on MARCS models is applied to derive precise differential abundance ratios of Na, Mg, Si, Ca, Ti, Cr, and Ni with respect to Fe. Results. The halo stars fall into two populations, clearly separated in [α/Fe], where α refers to the average abundance of Mg, Si, Ca, and Ti. Differences in [Na/Fe] and [Ni/Fe] are also present with a remarkably clear correlation between these two abundance ratios. Conclusions. The "high-α" stars may be ancient disk or bulge stars "heated" to halo kinematics by merging satellite galaxies or they could have formed as the first stars during the collapse of a proto-Galactic gas cloud. The kinematics of the "low-α" stars suggest that they have been accreted from dwarf galaxies, and that some of them may originate from the ω Cen progenitor galaxy.

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Calculation of the local standard of rest from 20574 local stars in the New Hipparcos Reduction with known radial velocities

Cited by 63 publications

References 48 publications

The observed spiral structure of the Milky Way

The observed spiral structure of the Milky Way

Radial velocities of K–M dwarfs and local stellar kinematics

Two distinct halo populations in the solar neighborhood

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