H II, or H +, consists of free protons. An H I region consists of neutral atomic hydrogen, and a molecular cloud of molecular hydrogen, H 2. A few of the brightest H II regions are visible to the naked eye. However, none seem to have been noticed before the advent of the telescope in the early 17th century.

Huntington Ingalls Industries, Inc. (HII) is the largest military shipbuilding company in the United States as well as a provider of professional services to partners in government and industry. HII, ranked No. 375 on the Fortune 500, was formed on 31 March 2011, as a divestiture from Northrop Grumman. [6] [7]

An HI region or H I region (read H one) is a cloud in the interstellar medium composed of neutral atomic hydrogen (HI), in addition to the local abundance of helium and other elements. (H is the chemical symbol for hydrogen, and "I" is the Roman numeral.

HII regions are emission nebulae created when young, massive stars ionise nearby gas clouds with high-energy UV radiation. They are composed primarily of hydrogen, hence the name (astronomers use the term HII to refer to ionised hydrogen, HI for neutral hydrogen), and have temperatures of around 10,000 Kelvin.

Some of the most beautiful extended objects that we can see are HII regions, or diffuse or emission nebulae. So-named because they contain mostly ionized hydrogen (H+ or HII), HII regions are found throughout the interstellar medium in the Galaxy and in other galaxies.

H II region, interstellar matter consisting of ionized hydrogen atoms. The energy that is responsible for ionizing and heating the hydrogen in an emission nebula comes from a central star that has a surface temperature in excess of 20,000 K. The density of these clouds normally ranges from 10 to

2024年1月8日 · H II regions (also spelled as HII regions), formally known as ionized atomic hydrogen regions, represent distinct cosmic zones characterized by the prevalence of ionized atomic hydrogen (H II). These regions owe their ionization to the intense ultraviolet radiation emitted by nearby hot, massive stars.

In this project you will follow the footsteps of Hubble, Bowen, and Zanstra in particular, to determine certain ionic abundances in H II regions. From this you will determine the effective temperature of the ultraviolet spectrum, and compare this to the properties of the candidates among the stars that could be providing this ionizing radiation.

“HII” is shorthand for ionized (missing one electron) hydrogen, since the massive, hot stars emit ultraviolet radiation that ionizes atoms in the gas. The gas in HII regions exists in a state in which it will produce emission lines that can tell us about the physical properties of the HII region.

2021年6月23日 · HII regions are volumes around massive stars where H is fully ionized by the intense stars UV flux. The volume is limited by the so called Stroemgren sphere, whose size depends critically on the amount of dust inside the sphere. …