An H II region is a region of interstellar atomic hydrogen that is ionized. [1] It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic centimetre.

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 H-II (H2) rocket was a Japanese satellite launch system, which flew seven times between 1994 and 1999, with five successes. It was developed by NASDA in order to give Japan a capability to launch larger satellites in the 1990s. [1]

电离氢区 （H II區）是發光的 氣體 和 電漿 組成的雲氣，有時會有數百 光年 的直徑，是 恆星 誕生的場所。 從這些氣體中誕生的 年輕、炙熱的藍色恆星 散發出大量的 紫外線，使 星雲 環繞在周圍的氣體游離。 H II區在數百萬年的歲月中也許可以誕生成千上萬顆的恆星。 最後， 超新星 爆炸和來自 星團 中質量最大的那些恆星吹出的強烈 恆星風，將會吹散掉H II區的氣體，留下來的就是像 昴宿星團 這樣的星團。 H II區是因為有大量 游離 的 氫 原子而得名的， 天文學家 同樣的將 中 …

电离氢区也叫HII区，它们是以氢为主要成分的星际气体云。 若星云附近有比较年轻的炽热恒星，则本来是中性的氢（中性氢区也叫HI区）会被恒星的紫外辐射电离，形成电离氢区——这样的电离氢区就是弥漫的大面积发射星云，激发星云的恒星必须是能发出大量紫外辐射的O型或B型星，这些星的表面温度高达几万度，星云的温度也可以达到上万度。 此外，当星际云之间的密度非常低时，中性氢原子在宇宙线的作用下也会电离。 电子和质子一旦分开，就不容易再复合，从而也 …

H II regions are clouds of ionized gas surrounding O stars, associated with molecular clouds. The gas is ionized by ultraviolet light from these massive young stars, recently formed from molecular clouds.

h-ii运载火箭（ h-ii ）是日本的卫星发射运载器，在1994年至1999年间发射了七次，成功五次。 由 NASDA （ 日语 ： 宇宙開発事業団 ） 研发，用于满足日本1990年代发射大型卫星的需要。

Areas in space which are luminous with the emission spectrum of ionized hydrogen are called H II regions. They are associated with the presence of massive O-type and B-type stars. Such stars, having surface temperatures in the range 15,000 - 30,000K, have characteristic blackbody radiation curves which peak in the ultraviolet .

The H-II launch vehicle, the central rocket in Japan's space program, with the capability to launch a two-ton class satellite into geostationary orbit, is a two-stage rocket that was developed with Japanese independent technology in all stages.

2017年6月20日 · We present a tutorial on the determination of the physical conditions and chemical abundances in gaseous nebulae. We also include a brief review of recent results on the study of gaseous nebulae, their relevance for the study of stellar evolution, galactic chemical evolution, and the evolution of the universe.