Dynamical Evolution and Spectral Characteristics of the Stellar Group Mamajek 2

• Published in: The Astrophysical journal Vol. 691; no. 1; pp. 212 - 218
• Main Authors: Jilinski, E, Ortega, V. G, de la Reza, R, Drake, N. A, Bazzanella, B
• Format: Journal Article
• Language: English
• Published: IOP Publishing 20-01-2009
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/691/1/212

The dynamical evolution of the recently detected stellar group Mamajek 2 is studied by means of its past three-dimensional orbit. The past orbits of the open clusters NGC 2516 and alpha Persei, belonging to the so-called 'Local Association,' were also computed in order to check for a possible common past dynamical evolution of these systems. To complete the data of the Mamajek 2 small group, we have obtained high-resolution FEROS spectra to measure the radial and also the projected rotational velocities of its members; an estimate of its metallicity was obtained as well. Two exceptionally low-rotating A-type stars turned out to be a strong magnetic Ap star in one case, and a normal A0 star with near-solar metallicity in the other. The dynamical results showed that NGC 2516 and Mamajek 2 may have had a common origin at the age of 135 ± 5 Myr. This dynamical age confirms the individual ages of 140 Myr for NGC 2516 and 120 ± 25 Myr for Mamajek 2 obtained independently by photometric methods. Both these groups appear to have the same solar metallicity giving support to a common birth scenario. The dynamical approach is showing that some bound open clusters can form in a coeval fashion with unbound stellar groups or with associations.