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| Paper: |
The VLT-FLAMES Tarantula Survey: Multiplicity and Dynamics of the Massive Stars in 30 Dor |
| Volume: |
465, Four Decades of Massive Star Research - A Scientific Meeting in Honor of Anthony J. Moffat |
| Page: |
284 |
| Authors: |
Sana, H.; Dunstall, P. R.; Hénault-Brunet, V.; Walborn, N. R.; de Koter, A.; de Mink, S. E.; Dufton, P. L.; Evans, C. J.; Maíz Apellániz, J.; Taylor, W. D.; Vink, J. S. |
| Abstract: |
We present the first results on the multiplicity and dynamics of the OB star population in 30 Dor obtained in the framework of the VLT-FLAMES Tarantula Survey. Based on their radial velocity (RV) variations, we have identified over 100 O-type and about 160 B-type spectroscopic binaries. The observed spectroscopic binary fraction for the O and B stars in our sample is of the order 30-35%. Preliminary considerations on the binary detection rate suggest a true spectroscopic binary fraction of the order of 50%. The overall RV dispersion (σRV) of the O stars in the complete sample is about 10 km s-1 but we note that the NGC 2060 and NGC 2070 regions show slightly different dynamical properties. We identified 17 O-type runaway candidates that show deviating RVs. One third of these candidates are On/nn/nnn stars, indicating a large rotational velocity. We show that the fast rotators have different RV properties than the average of the sample and are distributed throughout the field. This suggests a link between large rotation rate and peculiar RVs and, ultimately, the runaway phenomenon. Using the O stars observed within 25″(∼ 6 pc) from the core of R136, we obtain a preliminary upper limit of 7.5 km s-1 to σdyn. Given that this value has yet to be corrected down for contributions of non-detected long period binaries, this indicates that R136 is possibly a dynamically stable cluster. |
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