A Synthesis of Fundamental Parameters of Spiral Arms, Based on Recent Observations in the Milky Way

Jacques P. Vallée

National Research Council Canada, National Science Infrastructure portfolio, Victoria, Canada.

DOI: 10.4236/ijaa.2013.31003                

Abstract

Recent advances in the position and shape of each spiral arm in the Milky Way (pitch angle, shape, number, inter-arm separation at the Sun) are evaluated and compared, and a statistical analysis yields an updated idealized Galactic map. Earlier tabular results were published in five blocks of 15 to 20 each, covering 1980 to 2007 [1-4]. This paper presents the latest two blocks, each between 15 and 20 entries of published spiral arm researches since 2008. Using this revised Galactic map, and a discussion on the width of the Sagittarius arm (major or minor or equal), an interpretation of orbital streamlines for the gas and magnetic fields is presented for 2 major arms and for 4 major arms in the Milky Way. Our interpretation for all the recent data favors the following: a four-arm non-circular spiral pattern for the Milky Way; the Sagittarius arm being likely an equal arm; the inter-arm separation at the Sun’s location converging near 3.0 kpc. We emphasize that these conclusions encompass all the data, and thus can vary somewhat from the results of data obtained from a single filter (only CO data, say).

Keywords

Interstellar Matter; Milky Way; Spiral Galaxies

Conflicts of Interest

The authors declare no conflicts of interest.

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