The Calibration of Mid-Infrared Star Formation Rate Indicators
D. Calzetti, R. C. Kennicutt, C. W. Engelbracht, C. Leitherer, B. T. Draine, L. Kewley, J. Moustakas, M. Sosey, D. A. Dale, K. D. Gordon, G. X. Helou, D. J. Hol… 展开作者
D. Calzetti, R. C. Kennicutt, C. W. Engelbracht, C. Leitherer, B. T. Draine, L. Kewley, J. Moustakas, M. Sosey, D. A. Dale, K. D. Gordon, G. X. Helou, D. J. Hollenbach, L. Armus, G. Bendo, C. Bot, B. Buckalew, T. Jarrett, A. Li, M. Meyer, E. J. Murphy, M. Prescott, M. W. Regan, G. H. Rieke, H. Roussel, K. Sheth, J. D. T. Smith, M. D. Thornley, F. Walter
备注：
67 pages, 15 figures, accepted for publication on the Astrophysical Journal; replacement contains: correction to equation 8; important tweaks to equation 9; various typos corrected
With the goal of investigating the degree to which the mid-infrared emission traces the star formation rate (SFR), we analyze Spitzer 8 um and 24 um data of star-forming regions in a sample of 33 nearby galaxies with available HST/NICMOS images in the Paschen-alpha (1.8756 um) emission line. The galaxies are drawn from the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample, and cover a range of morphologies and a factor ~10 in oxygen abundance. Published data on local low-metallicity starburst galaxies and Luminous Infrared Galaxies are also included in the analysis. Both the stellar-continuum-subtracted 8 um emission and the 24 um emission correlate with the extinction-corrected Pa-alpha line emission, although neither relationship is linear. Simple models of stellar populations and dust extinction and emission are able to reproduce the observed non-linear trend of the 24 um emission versus number of ionizing photons, including the modest deficiency of 24 um emission in the low metallicity regions, which results from a combination of decreasing dust opacity and dust temperature at low luminosities. Conversely, the trend of the 8 um emission as a function of the number of ionizing photons is not well reproduced by the same models. The 8 um emission is contributed, in larger measure than the 24 um emission, by dust heated by non-ionizing stellar populations, in agreement with previous findings. Two SFR calibrations, one using the 24 um emission and the other using a combination of the 24 um and H-alpha luminosities (Kennicutt et al. 2007), are presented. No calibration is presented for the 8 um emission, because of its significant dependence on both metallicity and environment. The calibrations presented here should be directly applicable to systems dominated by on-going star formation.
The HST Key Project on the Extragalactic Distance Scale XXVI. The Calibration of Population II Secondary Distance Indicators and the Value of the Hubble Constant
An Improved uvby-Metallicity Calibration for Metal-Rich Stars
我们提出了一个改进的UVby-metallicity关系校准F，G，和早期K矮星，和一个类似的UVby-T（eff）的关系，都来自使用Levenberg-Marquardt最小化计划。我们的校准是基于1533颗恒星，这些恒星出现在Cayrel de Strobel（2001）的金属丰度汇编和Hauck-Mermilliod（1998）的紫外测光表中。我们还研究了推测的可能性，使用紫外测光产生的紫外-平面度校准。我们的结论是，虽然可能没有强有力的光度指标的存在或不存在的短周期行星，光谱指标的行星性的可能性是值得研究的。
