Astronomers have known for decades that stars are created out of the huge amount of gas in the universe. As gases are drawn together by gravity, the slow process of star formation begins.
But the gases in the star fields are not just atoms. All molecules should be in the form of ice except for some hydrogen and helium molecules at 10 degrees Kelvin in the depths of space. But observations have demonstrated that clouds of heavier compounds exist in space.
A team of scientists at Hokkaido University have shown that a process called chemical desorption could explain the existence of these molecular clouds. These occasional molecular clouds are composed of water, H2S, methanol, and other compounds. Stars form in these clouds as gravity continues its work. Stars coalesce into galaxies. The universe takes on form and sometimes, life.
But how do galaxies die? The question may seem relatively unimportant to us when we’re talking about a time span of 14 billion years, but astronomers still want to know.
The oldest galaxies are elliptical in shape, dim in comparison to the younger spiral galaxies. Their decreased brightness is due to the fact that most of the stars in these galaxies are old and dying. Very few new stars are being born. That makes the elusive elliptical galaxies harder to find.
Elliptical galaxies are classified according to a system developed by Edwin Hubble in 1926. The classifications range from E0 for an almost circular galaxy to E7 for a very stretched out one. They range in size from dwarf elliptical galaxies, less than 10% of the size of the Milky Way, to one of the largest known galaxies in the universe, M87.
A team of astronomers at Durham University in the UK recently published an article in January of 2021 in the journal, Nature Astronomy. The team discovered an elliptical galaxy, ID2299, that is in the process of expelling almost 50% of the gas available to it for forming stars. It is disgorging enough gas to create 10,000 suns every year. It is also creating new stars at a much faster rate than the Milky Way which consumes a lot of the gas as well. At the rate it’s going, ID2299 will go cold in just a few tens of millions of years instead of the usual billions.
Elliptical galaxies are formed when galaxies merge. Mergers are not uncommon. In fact, the Milky Way is on a collision course with the Andromeda galaxy, the event to take place in a few billion years. And as the star systems collide, a long tail, called a tidal tail, is formed. These are difficult to see, being relatively dim, composed of scattered suns and gases, escaping from the galaxy. The tails are created by the tidal forces of the two galaxies. ID2299 is the first galaxy identified as dying. ID2299’s tail was discovered because it is so far away in the distant universe. The light we see comes to us from a time when the universe was 4.5 billion years old. The tail was relatively bright then. Our universe is now 14 billion years old.
These findings place doubt on the ‘galactic wind’ theory that postulated a massive black hole at the center of elliptical galaxies, sucking the gases out and creating the ‘galactic wind’.
The astronomers have shown that the merger of galaxies is an essential part of the evolution of galaxies. The resultant galaxy loses a huge part of its star forming gases and starts the long road to death.
Most of the stars in our universe are found in elliptical galaxies now. Recent findings have confused astronomers as to the rate of expansion of the universe. Recent findings have confused astronomers as to the rate of expansion of the universe. In fact, there is dissention about whether the universe is expanding at all. But the large number of dying elliptical galaxies indicates that this universe is on the road to dissolution.
