Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007a%26a...470..161r&link_type=abstract
Astronomy and Astrophysics, Volume 470, Issue 1, July IV 2007, pp.161-171
Astronomy and Astrophysics
Astrophysics
45
Galaxy: General, Galaxy: Kinematics And Dynamics, Galaxy: Structure, Ism: Hii Regions
Scientific paper
Aims:Our aim is to determine the distance of outer Galaxy star-forming complexes in order to model the kinematic structure of our Galaxy. Methods: We searched for exciting star(s) of HII regions, with poor or unknown stellar distance, in the second and third galactic quadrants. We carried out spectroscopic and photometric (when necessary) observations in order to establish their spectral type and their U, B and V magnitudes. From these data, complemented with literature data, we determine the spectro-photometric distance of their associated complexes. Results: We (re)established the stellar distance of 23 star forming complexes. Reinvestigating the kinematics of the Perseus and Cygnus arms, we determined the velocity departures from circular rotation and we interpreted them as streaming motions in the spiral arms. Indeed, in addition to the Perseus arm where such departures were known for a long time, we added evidence for velocity deviations in the Cygnus arm. Most significant is that we found the opposite sign for these departures in the Perseus and Cygnus arms, which suggests that the co-rotation radius is located between these two arms at ~13 kpc from the galactic center.
Based on observations collected at the Haute-Provence Observatory. Appendix A is only available in electronic form at http://www.aanda.org
Adami Chris
Georgelin Y. M.
Russeil Delphine
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