Morphology and metallicity of the Small Magellanic Cloud using RRab stars

作者：Deb Sukanta^*; Singh Harinder P; Kumar Subhash; Kanbur Shashi M

来源：Monthly Notices of the Royal Astronomical Society, 2015, 449(3): 2768-2783.

DOI：10.1093/mnras/stv358

• stars: fundamental parameters
• stars: Population II
• stars: variables: RR Lyrae
• Magellanic Clouds
• galaxies: statistics
• galaxies: structure

We present a study of three-dimensional structure of the Small Magellanic Cloud (SMC). The V- and I-band light curves of the fundamental mode RR Lyrae (RRab) stars obtained by the Optical Gravitational Lensing Experiment-III project were utilized in order to comprehend the SMC structure. The [Fe/H]-P-phi(31) relation of Jurcsik & Kovacs is exploited to obtain the metallicities. From the three-dimensional RRab distance distributions, north-east arm and main body of the galaxy are identified. Combining metallicities with spatial distribution of these tracers, no radial metallicity gradient in the SMC has been detected. Dividing the entire sample into three parts: north-eastern, central and south-western, we find that the central part has a significantly larger line of sight depth as compared to rest of the parts, indicating that the SMC may have a bulge. Results obtained from the I-band data seem to be reliable and were further substantiated using the Smolec relation. Distribution of SMC RRab stars was modelled as a triaxial ellipsoid. Errors in structural parameters of the SMC ellipsoid were obtained from Monte Carlo simulations. We estimated the axes ratios of the galaxy as 1.00 +/- 0.000: 1.310 +/- 0.029: 8.269 +/- 0.934, the inclination of the longest axis with line of sight i = 2 degrees.265 +/- 0 degrees.784 and the position angle of the line of nodes theta(lon) = 74 degrees.307 +/- 0 degrees.509 from the variance weighted I-band determinations.

• 出版日期2015-5-21