Geometric Aspects and Testing of the Galactic Center Distance Determination from Spiral Arm Segments

Abstract

We consider the problem of determining the geometric parameters of a Galactic spiral arm from its segment by including the distance to the spiral pole, i.e., the distance to the Galactic center ($R_0$). The question about the number of points belonging to one turn of a logarithmic spiral and defining this spiral as a geometric figure has been investigated numerically and analytically by assuming the direction to the spiral pole (to the Galactic center) to be known. Based on the results obtained, in an effort to test the new approach, we have constructed a simplified method of solving the problem that consists in finding the median of the values for each parameter from all possible triplets of objects in the spiral arm segment satisfying the condition for the angular distance between objects. Applying the method to the data on the spatial distribution of masers in the Perseus and Scutum arms (the catalogue by Reid et al. (2014)) has led to an estimate of $R_0=8.8\pm 0.5$ kpc. The parameters of five spiral arm segments have been determined from masers of the same catalogue. We have confirmed the difference between the spiral arms in pitch angle. The pitch angles of the arms revealed by masers are shown to generally correlate with $R_0$ in the sense that an increase in $R_0$ leads to a growth in the absolute values of the pitch angles.

arXiv comment32 pages, 15 figures, 7 tables. Published in Astronomy Letters (AL)

References in corpus (18)

• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• ON the Nature of the Local Spiral Arm of the Milky Way
• 3D Distribution of Molecular Gas in the Barred Milky Way
• The Age and Structure of the Galactic Bulge from Mira Variables
• 3D stellar kinematics at the Galactic center: measuring the nuclear star cluster spatial density profile, black hole mass, and distance
• The Milky Way Spiral Structure Parameters from Data on Masers and Selected Open Clusters
• On the Spiral Structure of the Milky Way Galaxy
• Clustering of Local Group distances: publication bias or correlated measurements? IV. The Galactic Center
• Pitch angle variations in spiral galaxies
• The origin and orbit of the old, metal-rich, open cluster NGC 6791: Insights from kinematics
• Space Velocities of Southern Globular Clusters VII. NGC 6397, NGC 6626 (M 28) and NGC 6656 (M 22)
• Classical Cepheids and the spiral structure of the Milky Way
• Evidence of a bisymmetric spiral in the Milky Way
• Structure and Dynamics of the Milky Way: The Evolving Picture
• Metallicity field and selection effects in spatial distribution of the Galactic globular cluster system

Cited by in corpus (11)

• A New Estimate of the Best Value for the Solar Galactocentric Distance
• Analysis of galaxy kinematics based on Cepheids from the Gaia DR2 Catalogue
• Modeling of Spiral Structure in a Multi-Component Milky~Way-Like Galaxy
• Segments of spiral arms of the Galaxy traced by classical Cepheids: Effects of age heterogeneity
• Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10%
• Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes
• Redetermination of the Parameters of the Galactic Spiral Pattern from Classical Cepheids
• Estimation of the Parameters of the Spiral Pattern in the Galaxy Based on a Sample of Classical Cepheids
• Analysis of the Distance Scales by Cepheids from the Gaia EDR3 Catalogue Data
• Numerical Study of Statistical Properties of the Galactic Center Distance Estimate from the Geometry of Spiral Arm Segments
• Modeling the vertical distribution of the Milky Way's flat subsystem objects