Based on a high resolution and high signal-to-noise ratio （S/N） spectral analysis of 90 solar-type stars, we have established several new metaUicity calibrations in the Tefr range [5600, 6500] K based on red spectra...Based on a high resolution and high signal-to-noise ratio （S/N） spectral analysis of 90 solar-type stars, we have established several new metaUicity calibrations in the Tefr range [5600, 6500] K based on red spectra with the wavelength range of 560-880 nm. The new metallicity calibrations are applied to determine the metallicity of solar analogs selected from Sloan Digital Sky Survey （SDSS） spectra. There is a good consistent result with the adopted value presented in SDSS-DR7 and a small scatter of 0.26 dex for stars with S/N 〉 50 being obtained. This study provides a new reliable way to derive the metallicity for solar-like stars with low resolution spectra. In particular, our calibrations are useful for finding metal-rich stars, which are missing in the SEGUE Stellar Parameter Pipeline.展开更多
B037 is of interest because it is both the most luminous and the most highly reddened cluster known in M31. Deep observations and high spatial resolution images with the Advanced Camera for Surveys on the Hubble Space...B037 is of interest because it is both the most luminous and the most highly reddened cluster known in M31. Deep observations and high spatial resolution images with the Advanced Camera for Surveys on the Hubble Space Telescope （HST） first showed that this cluster is crossed by a dust lane. Photometric data in the F606W and F814W filters obtained in this paper indicate that colors of （F606W - F814W） in the dust lane are redder-0.4 mag than ones in the other regions of B037. The HST images show that this dust lane seems to be contained in B037, instead of in the M31 disk or the Milky Way. As far as we know, the formation of dust requires gas with a rather high metallicity. However, B037 has a low metallicity of [Fe/H] =→1.07 ±0.20. So, it seems improbable that the observed dust lane is physically associated with B037. It is clear that the origin of this dust lane is worthy of future study. In addition, based on these images, we present the precise variation of ellipticity and position angle, and of surface brightness profile, and determine the structural parameters of B037 by fitting a single-mass isotropic King model. In the F606W filter, we derive the best-fitting scale radius r0 = 0.56±0.02＂ （= 2.16±0.08 pc）, a tidal radius rt = 8.6±0.4I＂ （= 33.1±1.5 pc）, and a concentration index c = log（rt/ro） = 1.19±0.02. In the F814W filter, we derive r0 = 0.56 4± 0.01H （_=2.16 ±0.04 pc）, rt = 8.9 ±0.3＂ （= 34.3±1.2 pc）, and c = log（rt/ro） = 1.20±0.01. The extinction-corrected central surface brightness is μ0 = 13.53±0.03 mag arcsec^-2 in the F606W filter, and 12.85±0.03 mag arcsec^-2 in the F814W filter. We also calculate the half-light radius at rh = 1.05±0.03＂（= 4.04±0.12 pc） in the F606W filter and rh =1.07±0.01＂（= 4.12±0.04 pc） in the F814W filter. In addition, we derived the complete magnitudes of B037 in the V and I bands by transforming the magnitudes from the ACS system to the standard system, which are in good agreement with previous ground-based broad- band photometry studies.展开更多
基金supported by the National Natural Science Foundation of China under grant Nos. 10673015,10821061,10973021,11078019,11073026the National Basic Research Program of China(973 program) No. 2007CB815103/815403+1 种基金the Academy program No.2006AA01A120the Youth Foundation of the National Astronomical Observatories of China
文摘Based on a high resolution and high signal-to-noise ratio （S/N） spectral analysis of 90 solar-type stars, we have established several new metaUicity calibrations in the Tefr range [5600, 6500] K based on red spectra with the wavelength range of 560-880 nm. The new metallicity calibrations are applied to determine the metallicity of solar analogs selected from Sloan Digital Sky Survey （SDSS） spectra. There is a good consistent result with the adopted value presented in SDSS-DR7 and a small scatter of 0.26 dex for stars with S/N 〉 50 being obtained. This study provides a new reliable way to derive the metallicity for solar-like stars with low resolution spectra. In particular, our calibrations are useful for finding metal-rich stars, which are missing in the SEGUE Stellar Parameter Pipeline.
基金supported by the National Natural Science Foundation of China (Grant Nos.10873016 and 10633020)the National Basic Research Program of China (973 Program),No. 2007CB815403
文摘B037 is of interest because it is both the most luminous and the most highly reddened cluster known in M31. Deep observations and high spatial resolution images with the Advanced Camera for Surveys on the Hubble Space Telescope （HST） first showed that this cluster is crossed by a dust lane. Photometric data in the F606W and F814W filters obtained in this paper indicate that colors of （F606W - F814W） in the dust lane are redder-0.4 mag than ones in the other regions of B037. The HST images show that this dust lane seems to be contained in B037, instead of in the M31 disk or the Milky Way. As far as we know, the formation of dust requires gas with a rather high metallicity. However, B037 has a low metallicity of [Fe/H] =→1.07 ±0.20. So, it seems improbable that the observed dust lane is physically associated with B037. It is clear that the origin of this dust lane is worthy of future study. In addition, based on these images, we present the precise variation of ellipticity and position angle, and of surface brightness profile, and determine the structural parameters of B037 by fitting a single-mass isotropic King model. In the F606W filter, we derive the best-fitting scale radius r0 = 0.56±0.02＂ （= 2.16±0.08 pc）, a tidal radius rt = 8.6±0.4I＂ （= 33.1±1.5 pc）, and a concentration index c = log（rt/ro） = 1.19±0.02. In the F814W filter, we derive r0 = 0.56 4± 0.01H （_=2.16 ±0.04 pc）, rt = 8.9 ±0.3＂ （= 34.3±1.2 pc）, and c = log（rt/ro） = 1.20±0.01. The extinction-corrected central surface brightness is μ0 = 13.53±0.03 mag arcsec^-2 in the F606W filter, and 12.85±0.03 mag arcsec^-2 in the F814W filter. We also calculate the half-light radius at rh = 1.05±0.03＂（= 4.04±0.12 pc） in the F606W filter and rh =1.07±0.01＂（= 4.12±0.04 pc） in the F814W filter. In addition, we derived the complete magnitudes of B037 in the V and I bands by transforming the magnitudes from the ACS system to the standard system, which are in good agreement with previous ground-based broad- band photometry studies.
