On the Sun's distance from the center and the shape of the inner halo in the Galaxy: Gaia EDR3, HST and literature globular clusters

Evgeny Griv, Michael Gedalin, Ing Guey Jiang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

A statistical method is used to derive both the Sun's distance r0 from the Galactic Center (GC) and the 3D geometry of the inner (< 25 kpc) halo. The spatial distribution of the 138 Gaia EDR3 globular clusters (GCs) with distances established on a combination of HST and literature data of Baumgardt and Vasiliev (2021) is explored. An estimate by using these ancient objects of the pressure-supported subsystem of the Galaxy with newly derived distances leads to the mean r0=7.81±0.14 kpc. The distribution of GCs within 25 kpc is almost spherically symmetric, and has the shape of an ellipsoid with a major axis of its symmetry slightly elongated toward the Sun and two minor axes of almost the same length. The obtained scale-length ratio of the major axis to the minor axis in the plane and to the vertical axis of the ellipsoid is ≈ 1:0.8:0.7. Based on the papers of a series, for practical use we argue to employ the following Sun's distances from the GC and the plane: r0=8.15±0.15 kpc and z0=15±5 pc.

Original languageEnglish
Article number101758
JournalNew Astronomy
Volume93
DOIs
StatePublished - 1 May 2022

Keywords

  • Fundamental parameters – Galaxy
  • Galaxy
  • Kinematics and dynamics – Galactic halo – Galaxy
  • Structure

ASJC Scopus subject areas

  • Instrumentation
  • Astronomy and Astrophysics
  • Space and Planetary Science

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