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3032029 
Journal Article 
MULTICOLOR UBVRI POLARIMETRY OF NGC 4755 AND THE beta CEPHEI POPULATION 
Irene Vega, E; Maria Orsatti, Ana; Martinez, RE 
2015 
1 
Revista Mexicana de Astronomia y Astrofisica
ISSN: 0185-1101 
51 
1 
75-90 
WOS:000352521100009 
We present UBVRI polarimetric observations of 66 stars in the direction of NGC 4755, including eleven beta cephei stars. About half of these variables show indications of intrinsic polarization, but according to the theory neither radial nor non-radial pulsations could cause such polarizations. From the main characteristics of their P-V vs. lambda(V) curves we found as a possible origin, in some cases, scattering of light in extended atmospheres and suspected binarity, in some cases. The parameters of the interstellar medium towards the cluster are P-V = -2.76 +/- 0.13(%) and theta(V) = 76 degrees.6 0 degrees.9; the mean wavelength of maximum polarization amounts to 0.56 +/- 0.04 mu m. The value of polarization efficiency is higher than the mean, indicating a good alignment of the dust particles. A total of 25 stars were identified as members of NGC 4755; the identification task was improved through the use of polarimetric tools. 
ISM: dust, extinction; open clusters and associations: NGC 4755; stars: variables: beta Cephei