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the dusty s - cluster object ( dso / g2 ) , which was found in 2012 as a faint object approaching sgr  a * @xcite , can be primarily tracked in @xmath2-band continuum and recombination line emission , mainly br@xmath3 in @xmath4 band .
so far dso has remained compact in br@xmath3 line emission both before and after the periapse , see the analysis in @xcite and @xcite .
@xcite detected the first @xmath4-band identification of this source in the continuum imaging data with a magnitude of 18.9 . in fig .
[ fig1 ] ( middle row ) we show the evolution of br@xmath3 emission in line maps for the epochs 2008 - 2012 . combined with the compact continuum @xmath2-band emission @xcite , the observations have shown that the dso did neither stretch significantly nor disintegrate as was previously claimed @xcite .    in
@xcite we use the near - infrared polarimetric imaging data to determine the polarization properties of the dso for the first time .
in addition to the study of continuum and line emissions from the dso , the analysis of the @xmath4 -band polarimetry data allows us to determine the properties of this source .
the dust properties and the object geometries can be estimated quantitatively by the polarization analysis .      *
the dso has a @xmath4-band continuum counterpart with the flux density of @xmath5 , which corresponds to approximately @xmath6 magnitude . *
the dso is an intrinsically polarized source with the stable polarization degree of @xmath0 , see fig .
[ fig1 ] , top row . in different
observing years ( 2008 - 2012 ) , the measured polarization degree of this source is prominently higher than the foreground polarization which is 6.1% in @xmath4-band . *
the polarization degree stays approximately constant within uncertainties .
the significance of the linear polarization measurements from monte carlo simulations is larger than @xmath7 . *
the obtained polarization angle of the dso varies while the source moves towards the periapse ( see fig .
[ fig1 ] , bottom row ) .
the change in the polarization angle is due to the internal influences ( the circumstellar configuration ) and/or the external influences ( the source interaction with the accretion flow ) . *
the significant polarized emission as well as a large infrared excess may be explained by the model of a dust - enshrouded star that deviates from the spherical symmetry . *
the total and polarized flux density are matched by a composite stellar model consisting of the star , envelope , bipolar cavities , and the bow shock .
band in median deconvolved polarimetry images ( @xmath8 channel of naco imager ) in different epochs 2008 - 2012 .
bright spots correspond to stars . * middle row : * br@xmath3 line maps associated with the dso for the same years in @xmath9 sinfoni images .
contours correspond to the continuum emission of stars . * bottom row : * a sketch showing the dso polarization angle variation.,scaledwidth=75.0% ]
a peculiar source in the galactic center known as the dusty s - cluster object ( dso / g2 ) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014 . 
 its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry . for the first time 
 , we use near - infrared polarimetric imaging data to obtain constraints about the geometrical properties of the dso . 
 we find out that dso is an intrinsically polarized source , based on the significance analysis of polarization parameters , with the degree of the polarization of @xmath0 and an alternating polarization angle as it approaches the position of sgr  a*. since the dso exhibits a near - infrared excess of @xmath1 and remains rather compact in emission - line maps , its main characteristics may be explained with the model of a pre - main - sequence star embedded in a non - spherical dusty envelope .