ALMA witness how parent molecular clouds force their babies to eat
Did you notice that new born babies are eating all the time? Maybe that’s why they grow up so fast. One Taiwanese lullaby sings that my baby grows an inch every night! Stars form from massive clouds of dust and gas in space. They eat gas, not milk, to grow up. It’s common that several stars grow up together.
But there is a mystery behind the growth of baby stars. Some bigger stars refuse to eat when they reach certain mass level; such behavior occurs when conditions in their surroundings changed. When this happens, the fast-growing baby stars are just like children have poor appetite, they push foods away! That makes the moms really worry: “Why? What’s wrong with my baby?” Like the moms, astronomers also want to figure out: how the nature law controls the growing up stage of the big baby stars. They hope to witness how the parent molecular clouds are forcing these babies to eat.
By now we know that at the early star forming stage, gas clouds have a fluffy loose structure, and later, the cluster of gas cloud will start developing gas strips, consisted of gas molecular clouds. The clouds will distribute materials and feed the stars. Like a thin tube hardly noticeable, they provide secret channels so that the outer part materials still can go to the central region. After big stars finished their formation, huge stellar winds will blow off the remaining parts of the gas clouds, the surroundings will all be cleaned up. Here is a computer simulated video produced by Jim Dale showing that process. Let’s see how the strips form!
Unfortunately, computer simulation has its limit in telling us what is true. If you want to take a closer look at the places inside such regions in details, that’s where we need ALMA to come in and help.
People have long been wondering what’s really going on in those crowded central areas where materials are densely packed. This has been the very first time that some tiny spiral arms at the size of 1 light-year were spotted. Thanks to ALMA! Surprising to everyone, the latest ALMA pictures even caught for us the images of mini tiny gas arms. Can you see what is going on in there? Some of the gas cores are crashed by their own gravity and collapsed onto themselves to form future stars!
Besides being able to see things sharply, ALMA can also help predicting whether these gas cores are going to pass or fail the tests of becoming stars. If they failed, they are blown off by the stellar winds and never become stars. Well, the good news is, yes! They are all going to pass the tests!
This time, scientist turned the ALMA’s eyes to look at an object which is a cluster of dense cloud cores that soon are to turn to some stars. The object is at the constellation Serpent. Have you already guessed what makes this finding so difficult? Well, do you know that big stars usually grow fast and die young? Their number is not many. Even the closest big stars locate quite far away from us. When the stars are very far, observing their details is challenging. It takes patience and good study to well-prepare for a finding such as this one.
Who found it?
This time, the Taiwanese team which solved a big secret behind the growth of big stars is led by Dr. Hauyu Liu. He works at Academia Sinica, Institute of Astronomy and Astrophysics, in Taiwan. Remember that many stars grow up with several brothers and sisters? The next challenge Dr. Liu has planned is to count exactly how many stars really exist in the group. This requires him to see these clusters in finer details. Next time, he hoped that he could tell us which one of the following is true: do all the tiny gas cores’ going through the process of gravity crash and stars forming? Or, this case Dr. Liu found so rare that it cannot be found again in the universe?