Estimation of the Parameters of the Spiral Pattern in the Galaxy Based on a Sample of Classical Cepheids

Abstract

We consider a sample of Galactic classical Cepheids with highly accurate estimates of their distances taken from Skowron et al., where they were determined based on the period-luminosity relation. We have refined the geometric characteristics of two spiral arm segments-the Carina-Sagittarius and Outer ones. For this purpose, we have selected 269 Cepheids belonging to the Carina-Sagittarius arm with ages in the range 80-120 Myr. From them we have estimated the pitch angle of the spiral pattern $i=-11.9\pm 0.2^{\circ }$ and the position of this arm $a_0=7.32\pm 0.05$ kpc for the adopted $R_0=8.1\pm 0.1$ kpc. In the Outer arm we have selected 343 Cepheids with ages in the range 120-300 Myr. From them we have found $i=-11.5\pm 0.5^{\circ }$ and $a_0=12.89\pm 0.06$ kpc. Adhering to the model of a grand-design spiral pattern in the Galaxy with one pitch angle for all arms, we can conclude that this angle is close to $-12^{\circ }$.

14 pages, 5 figures, 4 tables

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Cited by in corpus (3)

• The Milky Way as Seen by Classical Cepheids II: Spiral Structure
• The Milky Way as Seen by Classical Cepheids I: Distances Based on Mid-infrared Photometry
• Redetermination of the Parameters of the Galactic Spiral Pattern from Classical Cepheids