by awitt » Mon Jun 14, 2010 2:59 pm
While I am always in awe of the mysteries the Universe presents to us, I am also impressed by the ingenuity of astronomers and astrophysicists to find answers. When it comes to the unusual colors of the RR, it would be great, if somehow links could have been provided to the papers by Schmidt, Cohen, & Margon (1980, ApJ, 239, L133), Cohen et al. (2004, AJ, 127, 2362), and Vijh et al. (2006, ApJ, 653, 1336)
Schmidt et al (1980) demonstrated that the red color of the RR is primarily caused by a powerful broad emission band (now known as ERE) in the red part of the optical spectrum. Vijh et al. (2006) showed, through narrow-band imaging, that this band dominates the X-shaped outflow structure.
The nearly spherical blue inner halo is largely caused by ordinary dust scattering, with some fluorescence by small neutral PAHs thrown i for good measure.
Cohen et al. (2004) published the first high-resolution HST image of the RR and provided a detailed analysis of its morphology and color distribution.
Our 2009 paper ( Witt et al. 2009, ApJ, 693, 1946) finally provided the answer to the mystery of of the origin of the EUV and FUV radiation in the RR, which is needed to explain the inner H II region in the nebula as well as the excitation of the ERE in the RR. There are numerous other bipolar protoplanetary nebulae which lack inner H II regions and ERE, although their chemistry and dust composition may be quite similar to that of the RR. What is lacking in them is a powerful source of EUV and FUV radiation, which in the case of the RR is provided by the hot accretion disk surrounding the secondary. This is the main reason why the color of the the RR appears to be so unusual.
Adolf N. Witt
University of Toledo
While I am always in awe of the mysteries the Universe presents to us, I am also impressed by the ingenuity of astronomers and astrophysicists to find answers. When it comes to the unusual colors of the RR, it would be great, if somehow links could have been provided to the papers by Schmidt, Cohen, & Margon (1980, ApJ, 239, L133), Cohen et al. (2004, AJ, 127, 2362), and Vijh et al. (2006, ApJ, 653, 1336)
Schmidt et al (1980) demonstrated that the red color of the RR is primarily caused by a powerful broad emission band (now known as ERE) in the red part of the optical spectrum. Vijh et al. (2006) showed, through narrow-band imaging, that this band dominates the X-shaped outflow structure.
The nearly spherical blue inner halo is largely caused by ordinary dust scattering, with some fluorescence by small neutral PAHs thrown i for good measure.
Cohen et al. (2004) published the first high-resolution HST image of the RR and provided a detailed analysis of its morphology and color distribution.
Our 2009 paper ( Witt et al. 2009, ApJ, 693, 1946) finally provided the answer to the mystery of of the origin of the EUV and FUV radiation in the RR, which is needed to explain the inner H II region in the nebula as well as the excitation of the ERE in the RR. There are numerous other bipolar protoplanetary nebulae which lack inner H II regions and ERE, although their chemistry and dust composition may be quite similar to that of the RR. What is lacking in them is a powerful source of EUV and FUV radiation, which in the case of the RR is provided by the hot accretion disk surrounding the secondary. This is the main reason why the color of the the RR appears to be so unusual.
Adolf N. Witt
University of Toledo