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تسجيل مستخدم جديدThe Gaia DR2 view of the Gamma Velorum cluster: resolving the 6D structure
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E. Franciosini
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Gaia-ESO Survey observations of the young Gamma Velorum cluster led to the discovery of two kinematically-distinct populations, Gamma Vel A and B, respectively, with population B extended over several square degrees in the Vela OB2 association. Using the Gaia DR2 data for a sample of high-probability cluster members, we find that the two populations differ not only kinematically, but are also located at different distances along the line of sight, with the main cluster Gamma Vel A being closer. A combined fit of the two populations yields $varpi_A = 2.895 pm 0.008$ mas and $varpi_B = 2.608 pm 0.017$ mas, with intrinsic dispersions of $0.038 pm 0.011$ mas and $0.091 pm 0.016$ mas, respectively. This translates into distances of $345.4^{+1.0+12.4}_{-1.0-11.5},$ pc and $383.4^{+2.5+15.3}_{-2.5-14.2},$ pc, respectively, showing that Gamma Vel A is closer than Gamma Vel B by $sim$38 pc. We find that the two clusters are nearly coeval, and that Gamma Vel B is expanding. We suggest that Gamma Vel A and B are two independent clusters located along the same line of sight.
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