Discovery of a primitive galaxy almost as large as the Milky Way Galaxy

The National Astronomical Observatory of Japan (国立天文台) and others (Koji Ohta and others of Kyoto University, Tohoku University and the University of Tokyo) discovered a primitive galaxy almost as large as the Milky Way Galaxy, and announced it in Nature Magazine, Aug. 1. 1996. Ohta, K., Yamada, T., Nakanishi, K., Kohno, K., Akiyama, M. and Kawabe, R., “Detection of Molecular Gas in the Quasar BR1202 – 0725 at Redshift z = 4.69” , Nature 382 (1996) 426

One of the farthest heavenly bodies (z=4.7*), quasar BR1202-0725 was observed with the Nobeyama Millimeter Array at NRO Cosmic Radio Facilities, a division of the National Astronomical Observatory of Japan. It was confirmed to contain a large quantity of carbon monoxide molecules.

At quasar BR1202-0725, at a distance of 14 billion light-years, or one billion years after the Big Bang 15 billion years ago, hydrogen molecular gas and carbon monoxide molecule were found. Their mass is 100 billion times that of as the sun, and equal to the total mass of our Galaxy.

This discovery brought epoch-making progress to research into the process from our galaxies formative period to its maturity. For example, we now know that there was carbon and hydrogen made in a star, in a young (one billion years old) galaxy.

Thin interstellar gas and interstellar matter form a thick area and this forms an interstellar molecular cloud**, then a star results from gravitational contraction.

A supernova is the final stage of a star that reduces the component atoms to an interstellar gas and interstellar dust.  The next circulation of a star’s formation begins.

In order of quantity, there are hydrogen, helium, oxygen, and carbon in space. We know that carbon, the main component of known life, exists as a carbon ion in interstellar gas, and as carbon monoxide in an interstellar molecular cloud.

* Z is a sign to represent the amount of redshift: the degree of how long a wavelength of light gets longer by Doppler shift while heavenly bodies recede from our position.

** interstellar molecular cloud: very thin gas, about 10 hydrogen atoms per 1 cm3, extends between stars in the Galaxy.  There are high-density areas (100-10000 hydrogen atoms per 1cm3) here and there, which seem like clouds. These are called interstellar molecular clouds. They measure several, or dozens of parsecs, with an absolute temperature of about 10 Kelvin. Their mass is typically hundreds or tens of thousands of times that of the sun. An interstellar molecular cloud whose mass is more than hundreds of thousands of times that of the sun is considered an especially huge molecular cloud. Stars are formed in a particularly high-density part of an interstellar molecular cloud by gravitational contraction. The main ingredient of an interstellar molecular cloud is mostly the hydrogen molecule (H2), secondly the helium atom (He), then the carbon monoxide molecule (CO). The ratio of hydrogen molecules to carbon monoxide molecules is about 10000:1.