TITLE:
A Synthesis of Fundamental Parameters of Spiral Arms, Based on Recent Observations in the Milky Way
AUTHORS:
Jacques P. Vallée
KEYWORDS:
Interstellar Matter; Milky Way; Spiral Galaxies
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.3 No.1,
March
29,
2013
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).