Many nebulae or stars form from the gravitational collapse of gas in the interstellar medium or ISM. As the material collapses under its own weight, massive stars may form in the center, and their ultraviolet radiation ionizes the surrounding gas, making it visible at optical wavelengths.he size of these nebulae, known as HII regions, varies depending on the size of the original cloud of gas. New stars are formed in the nebulae. The formed stars are sometimes known as a young, loose cluster. Some nebulae are formed as the result of supernova explosions, the death throes of massive, short-lived stars.
In addition, one vaccine for the prevention of H5N1 influenza, commonly referred to as avian influenza or âbird flu,â contains the adjuvant AS03, an oil-in-water emulsion.
Egg allergies and vaccines. Because influenza and yellow fever vaccines are both made in eggs, egg proteins (primarily ovalbumin) are present in the final products. 1  Yellow fever vaccine â In the case of the yellow fever vaccine, quantities are sufficient to cause allergic reactions in susceptible patients.gg allergies and vaccines. Because influenza and yellow fever vaccines are both made in eggs, egg proteins (primarily ovalbumin) are present in the final products. 1  Yellow fever vaccine â In the case of the yellow fever vaccine, quantities are sufficient to cause allergic reactions in susceptible patients.