<P> An H II region or HII region is a region of interstellar atomic hydrogen that is ionized . It is typically a 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 cm . The Orion Nebula , now known to be an H II region , was observed in 1610 by Nicolas - Claude Fabri de Peiresc by telescope , the first such object discovered . </P>
<P> An H II region or HII region is a region of interstellar atomic hydrogen that is ionized . It is typically a 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 cm . The Orion Nebula , now known to be an H II region , was observed in 1610 by Nicolas - Claude Fabri de Peiresc by telescope , the first such object discovered . </P>
where can ionized hydrogen be found in astronomy
where can ionized hydrogen be found in astronomy
star formation
star formation