The Sun's Distance from the Galactic Centre and Mid-Plane, and the Galactic Old Bulge's Morphology: 715 VVV Type II Cepheids

Evgeny Griv, Michael Gedalin, Pawel Pietrukowicz, Daniel Majaess, Ing Guey Jiang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

A statistical method is employed in tandem with new VISTA Variables in the Via Lactea (VVV) near-infrared observations to determine the Sun's distance from the Galactic Centre (r0, GC), the Sun's height from the local mid-plane (z0), and to likewise infer the shape of the Galactic ∼10 Gyr old bulge. Specifically, the conclusions stem from an investigation of 715 high-latitude (|b| > 1°) and centrally symmetric concentrated Type II Cepheids (T2Cs) recently identified in the VVV survey by Braga et al. The analysis yields r0 = 8.35 ± 0.10 kpc and z0 = 10 ± 2 pc. The T2Cs distribution within the effective bulge radius rbulge = 2-3 kpc is an ellipsoid exhibiting axial ratios of ≈1:0.7:0.6, with the major axis inclined at an angle θ ≈-3° to the Sun-GC sightline. T2Cs do not trace a prominent barred structure at distances >1 kpc from the GC. A key conclusion is that analyses of independent optical and infrared Optical Gravitational Lensing Experiment (OGLE) and VVV observations yield consistent results (e.g. r0 > 8.0 kpc and both observations display a comparable shape of an ellipsoid), thus providing a constrained and reduced systematic uncertainty.

Original languageEnglish
Pages (from-to)4194-4198
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Volume502
Issue number3
DOIs
StatePublished - 1 Apr 2021

Keywords

  • Galaxy: bulge
  • Galaxy: fundamental parameters
  • Galaxy: kinematics and dynamics
  • Galaxy: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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