Children with disabilities <a href=" http://www.jasonclarke.net/outline-for-college-research-paper/#seaman ">executive summary business plan</a> So what did the researchers find? It turns out that NGC 2392 has unusually high levels of X-ray emission compared to two other planetary nebulas that the scientists examined. Because of these emissions, it's very likely that NGC 2392 possesses an unseen companion-the interaction between a pair of binary stars could explain the elevated X-ray emissions. The fainter X-ray emission observed in the two other planetary nebulas, in contrast, is likely produced by shock fronts (like sonic booms) in the wind from the central star.