Open cluster birth analysis and multiple spiral arm sets in the Milky Way

Smadar Naoz, Nir J. Shaviv*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The Milky Way spiral arm kinematics is studied using the birth place of open clusters. We separately study the nearby spiral arms, and find evidence for multiple spiral sets. In particular, the Sagittarius-Carina arm appears to be a superposition of two sets. The first has a pattern speed of ΩP,Carina, 1 = 16.5- 1.4 sys+ 1.2 ± 1.1stat km s- 1 kpc- 1, while the second has ΩP,Carina, 2 = 29.8- 1.3 sys+ 0.6 ± 1.3stat km s- 1 kpc- 1. The Perseus arm located at larger galactic radii exhibits only one clear set with ΩP,Perseus = 20.0- 1.2 sys+ 1.7 ± 1.6stat km s- 1 kpc- 1. The Perseus and "slower" Carina arms are most probably part of an m = 4 set. The Orion "armlet" appears to have a pattern speed of ΩP,Orion = 28.9- 1.2 sys+ 1.3 ± 0.8stat km s- 1 kpc- 1. In other words, both the "faster" Carina arm and the Orion arm are nearly corotating with the solar system.

Original languageAmerican English
Pages (from-to)410-421
Number of pages12
JournalNew Astronomy
Issue number5
StatePublished - Jul 2007


  • Galaxy: kinematics
  • Open clusters and associations:general


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