There are an enigmatic population of massive stars around the Galactic Center
(GC) that were formed some Ma ago. A fraction of these stars has been found to
orbit the supermassive black hole, SgrA*, in a projected clockwise disk, which
suggests that they were formed in a formerly existing dense disk around SgrA*.
We focus on the extended, near-infrared (NIR) sources IRS1W, IRS5, IRS10W, and
IRS21 that have been suggested to be young, massive stars that form bow-shocks
through their interaction with the ISM. Their nature has impeded accurate
determination of their orbital parameters. We aim at establishing their nature
and kinematics to test whether they form part of the clockwise disk. We
performed NIR multi-wavelength imaging using adaptive optics (AO) and sparse
aperture masking (SAM). We introduce a new method for self-calibration of the
SAM PSF in dense stellar fields. The emission mechanism, morphology and
kinematics of the targets were examined via 3D bow-shock models. We confirm
previous findings that IRS21, IRS1W, and IRS5 are bow-shocks created by the
interaction between mass-losing stars and the interstellar gas. The nature of
IRS10W remains unclear. Our modeling shows that the bow-shock-emission is
caused by thermal emission while the scattering of stellar light does not play
any significant role. IRS 1W appears to be a bow-shock produced by an
anisotropic stellar wind or by locally inhomogeneous ISM density. Our best-fit
models provide an estimate of the local proper motion of the ISM in the NA in
agreement with the published models. Assuming that all of the sources are tied
to SgrA*, their orbital planes were obtained via a Monte-Carlo simulation. Our
orbital analysis suggests that they are not part of any of the clockwise disk.
We thus add more evidence to recent findings that a large part of the massive
stars show apparently random orbital orientations.Comment: accepted for publication by A&A, 17 pages, 11 figures, 1 appendi
