Astronomers have revealed the mysterious origin of two different gas flows from a baby star. Using ALMA, they found that the slow leakage and the high velocity jet of the proto-star had irregularly shaped axes and that the first one began to be thrown earlier than the latter. The origin of these two streams is a mystery, but these observations give signals that these two streams have been released from different parts of the disk around the prototype.
Stars in the universe have a wide range of masses ranging from hundreds of times the mass of the Sun to less than a tenth of that of the Sun. To understand the origin of this diversity, astronomers study the formation of the stars, aggregation of space gas and dust.
Baby stars collect the gas with their gravitational attraction, but part of the material is thrown away by the proto-stars. This discarded material forms a star cry for birth, which gives information about the mass accumulation process.
Yuko Matsushita, a college student at the University of Kyushu and her team, used ALMA to observe the detailed structure of the birth cry of the baby star MMS5 / OMC-3 and discovered two different gaseous streams: slow exit and rapid jet. There were several examples of two streams seen in the radio waves, but the MMS5 / OMC-3 is exceptional.
"By measuring the Doppler displacement of radio waves, we can estimate the speed and duration of gas flows," said Matsushita, the lead author of the study, Astrophysical Journal, "We found that the flow and leakage started 500 years and 1300 years ago, and these gas streams are quite young."
Even more interesting, the team found that the axes of the two streams were not aligned by 17 degrees. The axis of the streams can change for long periods of time due to the precession of the central star. But in this case, given the extraordinary youth of gas flows, the researchers concluded that the discrepancy is not due to the precession but is related to the start-up process.
There are two competing models for forming the mechanism of the protopter leaks and jets. Some researchers assume that the two streams are formed independently in different parts of the gas disk around the central baby star, while others suggest that the colored jet is formed first and then inserts the surrounding material to form the slower outflows. Despite the in-depth research, astronomers have not yet reached a definitive answer.
Discrepancy in both flows may arise in the "independent model" but is difficult in the "model of enthusiasm". In addition, the team found that the outflow was discarded much earlier than the jet. This clearly supports the "independent model".
"The observation corresponds well to the outcome of my simulation," says Masahiro Machida, a professor at Kyushu University. Ten years ago, he conducted pioneering simulation studies with the help of a supercomputer run by Japan's National Astronomical Observatory. In the simulation, the wide-angle outflow is ejected from the outside of the gas disk around the protuberance while the collimated jet is released regardless of the internal area of the disk. Machida goes on: "The observed discrepancy between the two gas streams may mean that the disk around the protopter is distorted."
"The high sensitivity of ALMA and high angular resolution will allow us to find more and more young energy systems such as MMS 5 / OMC-3," said Sakto Takahashi, an astronomer at the National Astronomical Observatory of Japan and the ALMA Joint Observatory and co-author of the article. "They will provide clues to understand leakage and jet motion mechanisms, and the study of such objects will also show us how mass and discard processes work at the earliest stage of star formation."
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