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Milky Way circular velocity curve measured from element abundances

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Research area:physics-astronomyastrophysics-stellar

What the study found

The study presents a new data-driven method for measuring the Milky Way’s circular velocity curve by using gradients in stellar element abundances. The authors report a circular velocity at the solar radius of 235.3 km s−1 from the [Mg/Fe] abundance ratio, along with estimates of the radial and azimuthal frequencies and the Oort constants.

Why the authors say this matters

The findings indicate that abundance ratios can trace stellar positions and motions in the Galactic disk, which the authors say enables an empirical measurement of the Galaxy’s circular velocity curve, epicyclic frequency, and azimuthal frequency. The study suggests this provides a way to study kinematic gradients across the Milky Way’s disk.

What the researchers tested

The researchers combined stellar surface abundances from the APOGEE survey with kinematic data from the Gaia mission. They tested a method that uses element abundance gradients in the plane of radial kinematics, focusing on average [Fe/H] and [Mg/Fe] patterns in the Milky Way disk.

What worked and what didn't

The results confirm ordered structure in the Milky Way’s disk in terms of average [Fe/H] and [Mg/Fe]. The authors suggest that 〈[Fe/H]〉 traces the radial positions of stars in the disk, while 〈[Mg/Fe]〉 traces orbital excursions around that radius. The method produced estimates of v_c,⊙ = 235.3−3.7+2.8 km s−1, κ0,R⊙ = 36.9−1.0+0.8 km s−1 kpc−1, Ω0,R⊙ = 28.5−0.1+0.4 km s−1 kpc−1, and Oort constants A = 16.5−0.1+0.1 km s−1 kpc−1 and B = −11.9−0.3+0.1 km s−1 kpc−1.

What to keep in mind

The abstract provided does not describe major limitations, but the reported measurements are tied to the solar radius and to the abundance ratio [Mg/Fe] as the most constraining tracer. The summary also stops before giving the full expression for the radial acceleration at the solar radius.

Key points

  • A new data-driven method uses stellar element abundance gradients to measure the Milky Way’s circular velocity curve.
  • APOGEE abundance data and Gaia kinematics were combined in the analysis.
  • Average [Fe/H] and [Mg/Fe] show ordered structure across the Milky Way’s disk.
  • The study reports v_c,⊙ = 235.3 km s−1 from [Mg/Fe] at the solar radius.
  • The authors also estimate the radial and azimuthal frequencies and the Oort constants.

Disclosure

Research title:
Milky Way circular velocity curve measured from element abundances
Authors:
Danny Horta, Adrian M. Price-Whelan, Sergey E. Koposov, Jason A. S. Hunt, David W. Hogg, Carrie Filion, Kathryn Daniel
Institutions:
Flatiron Health (United States), Flatiron Health (United States), Flatiron Health (United States), Flatiron Institute, Flatiron Institute, Flatiron Institute, Max Planck Institute for Astronomy, New York University, Royal Observatory, Royal Observatory, UK Astronomy Technology Centre, UK Astronomy Technology Centre, University of Arizona, University of Cambridge, University of Surrey
Publication date:
2026-03-10
DOI:
10.3847/1538-4357/ae43de
OpenAlex record:
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AI provenance: This post was generated by gpt-5.4-mini (OpenAI). The original authors did not write or review this post.

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