The spiral structure of our Milky Way Galaxy

By L. Hou, Jin Han, W. B. Shi. 2009

136 citations recorded by the source corpus.

Context. The spiral structure of our Milky Way Galaxy is not yet known. HII regions and giant molecular clouds are the most prominent spiral tracers. Models with 2−4 arms have been proposed to outline the structure of our Galaxy. Aims. Recently, new data of spiral tracers covering a larger region of the Galactic disk have been published. We wish to outline the spiral structure of the Milky way using all tracer data. Methods. We collected the spiral tracer data of our Milky Way from the literature, namely, HII regions and giant molecular clouds (GMCs). With weighting factors based on the excitation parameters of HII regions or the masses of GMCs, we fitted the distribution of these tracers with models of two, three, four spiral-arms or polynomial spiral arms. The distances of tracers, if not available from stellar or direct measurements, were estimated kinetically from the standard rotation curve of Brand & Blitz (1993, A&A, 275, 67) with R0 = 8.5 kpc, and Θ0 = 220 km s −1 or the newly fitted rotation curves with R0 = 8.0 kpc and Θ0 = 220 km s −1 or R0 = 8.4 kpc and Θ0 = 254 km s −1 . Results. We found that the two-arm logarithmic model cannot fit the data in many regions. The three- and the four-arm logarithmic models are able to connect most tracers. However, at least two observed tangential directions cannot be matched by the three- or four-arm model. We composed a polynomial spiral arm model, which can not only fit the tracer distribution but also match observed tangential directions. Using new rotation curves with R0 = 8.0 kpc and Θ0 = 220 km s −1 and R0 = 8.4 kpc and Θ0 = 254 km s −1 for the estimation of kinematic distances, we found that the distribution of HII regions and GMCs can fit the models well, although the results do not change significantly compared to the parameters with the standard R0 and Θ0.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2471dbe7bbe15838f982fa3c14f89642cb5c35aa

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. M. J. Reid
2. L. Hou
3. Jin Han
4. K. Menten
5. P. McMillan
6. A. Brunthaler
7. T. Dame
8. L. Moscadelli

In Instrumentation

1. M. J. Reid
2. L. Hou
3. Jin Han
4. K. Menten
5. K. Hachisuka
6. M. Sato
7. Y. Choi
8. T. Dame

Citations in the corpus

• The Bar and Spiral Structure Legacy (BeSSeL) Survey: Mapping the Milky Way with VLBI Astrometry† (2011, background): “However, almost all of these surveys are all only two dimensional, and using them to construct a three dimensional model of the Milky Way is not trivial, mainly due to large uncertainties in distance measurements (Georgelin & Georgelin 1976; Hou et al. 2009).”
• ON THE NATURE OF THE LOCAL SPIRAL ARM OF THE MILKY WAY (2013, background): “Churchwell et al. (2009) favor two arms from their investigation of counts of older stars, while observations of gas and dust indicate four- or five-arm models (Russeil 2003; Hou et al. 2009).”
• The observed spiral structure of the Milky Way (2014, methodology): “We update the catalogs of Galactic HII regions, GMCs, and 6.7GHz methanol masers, and then outline the spiral structure of the Milky Way.”