Sulfuric acid hydrate is another possible explanation for the contaminant observed spectroscopically. However, there are differences between them when researched spectroscopically. Be stars are often visually and spectroscopically variable. Being a simple molecule, ethylene is spectroscopically simple. The compound has now been synthesized and identified spectroscopically. Usually the equilibrium constant is so small that the enol is undetectable spectroscopically. It and HD 209458 b were the first two planets to be directly spectroscopically observed. Water ice has been spectroscopically detected on its surface. In STEM, EELS can be used to spectroscopically map a sample at atomic resolution. About 20 initial galaxy clusters have been identified spectroscopically. Efforts to isolate the asymmetric species spectroscopically are typically unsuccessful. For the neutral compound, the keto tautomers are undetectable spectroscopically. Its surface temperature has been spectroscopically estimated to be about 13,200 K. Unsaturated silanes, the silenes and silynes, have been characterized spectroscopically. Spectroscopically it is early F or late A with luminosity class Ia or Iab.