演講資訊

摘要：

In this talk, we first introduce a spectroscopy based Stellar Color Regression method to perform accurate color calibration for modern imaging surveys, taking advantage of millions of stellar spectra now available. As an illustration, we have applied the method to the SDSS Stripe 82 data and achieved an unprecedented calibration accuracy of about 5, 3, 2, and 2 mmag in colors u-g, g-r, r-i, and i-z, respectively. Using the re-calibrated Stripe 82 photometry, we demonstrate that the intrinsic widths of metallicity-dependent stellar loci of main-sequence stars are essentially zero. Based on this fact, we propose a Stellar Locus OuTlier (SLOT) method to determine binary fraction of main-sequence stars statistically. The method is sensitive to neither the period nor mass-ratio distributions of binaries, and applicable to large survey volumes that contain different stellar populations. Applying the method to Stripe 82, we find an average binary fraction for field FGK stars of 41 per cent. The fraction decreases toward stars of redder colors and probably higher metallicities. In the end, we propose a color offset -- velocity variation diagram to search for compact binary systems in the Galaxy, and discuss future work with the SLOT method.