December 5, 2012
Infant Solar System Caught In The Act Of Growing Up
Lee Rannals for redOrbit.com - Your Universe Online
The youngest still-forming solar system ever seen has been discovered by astronomers and reported about in the journal Nature.Astronomers found an infant star surrounded by a swirling disk of dust and gas more than 450 light-years from Earth in the constellation Taurus.
The star has about one-fifth the mass of the Sun, but the scientists say it will likely pull in material from its surroundings to eventually match the Sun's mass.
The disk surrounding the young star contains at least enough mass to make seven Jupiters.
"This very young object has all the elements of a solar system in the making," said John Tobin, of the National Radio Astronomy Observatory.
The solar system is no more than 300,000 years old, compared to our own 4.6-billion-year-old system. Tobin said it may even be younger than that, depending on how fast it accumulated mass in the past.
Astronomers said the young star is one of the closest examples of the earliest stages of star formation. They used the millimeter-wave observatories to detect both dust and carbon monoxide around the object.
They were the first observers to show that the young star is surrounded by a rotating disk of material, and were also the first to measure the mass of a true protostar.
The team showed by measuring the Doppler shift of radio waves that the rotation speed in the disk changes with the material's distance from the star in the same way the orbital speeds of planets change with distance from the Sun.
Hsin-Fang Chiang, of the University of Illinois and the Institute for Astronomy of the University of Hawaii, said this pattern, known as Keplerian rotation, is one of the first steps towards forming planets because the disk is supported by its own rotation.
"This is the youngest protostar found thus far to show that characteristic in a surrounding disk," Tobin said. "In many ways, this system looks much like we think our own Solar System looked when it was very young."
Past observations suggested the presence of a large disk surrounding the protostar. This motivated Tobin and his team to pursue high-resolution millimeter-wave observations.
The astronomers were granted time with the Atacama Large Millimeter/submillimeter Array (ALMA), an international telescope system nearing completion at high elevation in northern Chile, to help with their observations.
"ALMA's advanced capabilities will allow us to study more such objects at greater distances," Tobin said. "With ALMA, we will be able to learn more about how the disks form and how quickly the young stars grow to their full size, and gain a much better understanding of how stars and their planetary systems begin their lives."