National Astronomical Observatory of Japan

Snow Falling around Infant Solar System: Icy region gives planet and comet formation a boost

| Science

Astronomers using the new Atacama Larger Millimeter/submillimeter Array (ALMA) telescope have taken the first-ever image of a snow line in the disk of an infant solar system. This frosty landmark is thought to play in an essential role in the formation and chemical make-up of planets around a young star.

On Earth, snow lines typically form at high elevations where falling temperatures turn atmospheric moisture to snow. In much the same way, snow lines are thought to form around young stars in the distant, colder reaches of the disks from which solar systems form. Depending on the distance from the star, however, other more exotic molecules can freeze and turn to snow. Obtaining the picture of the snow lines of various molecules is important for studying how planets are formed and what differentiates the chemical composition of planets.

ALMA spotted a never-before-seen the snow line of carbon monoxide around a young star TW Hydrae. The CO snow line is located at 30 AU from the central star, which corresponds to the orbit of Neptune in our solar system. Astronomers believe this nascent solar system has many of the same characteristics that our own Solar System had when it was just a few million years old. In addition, CO ice is needed to form methanol, which is a building block of more complex organic molecules that are essential for life. These results tell us about the very early period in the history of our own solar system

The results were published in Science Express on 18 July 2013.

Illustration 1
Diazenylium (N2H+) is easy to react chemically with carbon monoxide (CO) gas, then it is difficult to exist in the area that fill with much carbon monoxide gas. So, the meaning of the radio wave from diazenylium is observed, it is indicating the carbon monoxide has frozen in the region.