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The large-scale kinematics of young stars in the Milky Way disc: first results from SDSS-V

2025· preprint· en· 0 citations· W4415090297 on OpenAlex· 10.48550/arxiv.2509.10387

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The three-model screen

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All three models called this out of scope.

stratum: fund_new · design weight: 1678.90 (the sample is stratified; any rate computed without the weight is wrong)
Claude Opus 4.8OUT
genre: empirical
about Canada: no
confidence: high

SDSS-V kinematic mapping of young OB stars in the Milky Way disc; the object is Galactic dynamics.

GPT-5.6 (high)OUT
genre: empirical
about Canada: no
confidence: high

This astronomical survey analyzes stellar kinematics in the Milky Way, not research itself.

Grok 4.5OUT
genre: empirical
about Canada: no
confidence: high

Galactic astronomy of young-star kinematics from SDSS-V; domain astrophysics.

Abstract

We present a first large-scale kinematic map of $\sim$50,000 young OB stars ($T_{\rm eff} \geq 10,000$ K), based on BOSS spectroscopy from the Milky Way Mapper OB program in the ongoing Sloan Digital Sky Survey V (SDSS-V). Using photogeometric distances, line-of-sight velocities and Gaia DR3 proper motions, we map 3D Galactocentric velocities across the Galactic plane to $\sim$5 kpc from the Sun, with a focus on radial motions ($v_R$). Our results reveal mean radial motion with amplitudes of $\pm 30$ km/s that are coherent on kiloparsec scales, alternating between inward and outward motions. These $\bar{v}_R$ amplitudes are considerably higher than those observed for older, red giant populations. These kinematic patterns show only a weak correlation with spiral arm over-densities. Age estimates, derived from MIST isochrones, indicate that 85% of the sample is younger than $\sim300$ Myr and that the youngest stars ($\le 30$ Myr) align well with density enhancements. The age-dependent $\bar{v}_R$ in Auriga makes it plausible that younger stars exhibits different velocity variations than older giants. The origin of the radial velocity features remains uncertain, and may result from a combination of factors, including spiral arm dynamics, the Galactic bar, resonant interactions, or phase mixing following a perturbation. The present analysis is based on approximately one-third of the full target sample. The completed survey will enable a more comprehensive investigation of these features and a detailed dynamical interpretation.

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The record

Venue
arXiv (Cornell University)
Topic
Astronomy and Astrophysical Research
Field
Physics and Astronomy
Canadian institutions
Funders
Leibniz-GemeinschaftUniversity of Colorado BoulderNational Astronomical Observatories, Chinese Academy of SciencesUniversity of Illinois at Urbana-ChampaignMax-Planck-Institut für AstronomieVlaamse regeringNew Mexico State UniversityNanjing UniversityYale UniversityUniversity of TorontoLeibniz-Institut für Astrophysik PotsdamFonds Wetenschappelijk OnderzoekNational Science FoundationYunnan UniversityBelgian Federal Science Policy OfficeÉcole Polytechnique Fédérale de LausanneSpace Telescope Science InstituteUniversidad Nacional Autónoma de MéxicoAlfred P. Sloan FoundationEuropean Space AgencyJohns Hopkins UniversityHarvard UniversityChina National Textile and Apparel CouncilCalifornia Institute of TechnologyOhio State UniversityCarnegie Institution of WashingtonSmithsonian Astrophysical ObservatoryFlatiron HealthSmithsonian Institution
Keywords
StarsRadial velocityMilky WayGalactic planeKinematicsSkySpiral galaxyAmplitude
Has abstract in OpenAlex
yes