The Birth of the Sun
New Observations Show Sun-like Star in Earliest Stage of Development
Members of a research team led by the University of Colorado at Boulder have used NASA’s Chandra X-ray Observatory to peer at the embryo of an infant star in the nearby Eagle Nebula, which they believe may someday develop into a virtual twin of Earth’s Sun.
The object, known as an evaporating gas globule, or EGG, has the same mass as the Sun and appears to be evolving in a violent environment much like the one believed to have produced Earth’s Sun, said researcher Jeffrey Linsky of JILA, a joint institute of CU-Boulder and the National Institute of Standards and Technology. Located in a region called the Pillars of Creation in the Eagle Nebula roughly 7,000 light-years from Earth, the object — dubbed E42 — is thought to be in the earliest stage astronomers have ever detected a star like the Sun, said Linsky.
A new image of the Pillars of Creation, consisting of a Hubble Space Telescope image overlaid with Chandra X-ray data, was released Feb. 15 by the Chandra X-ray Observatory Center in Cambridge, Mass. The image, which shows red, green and blue dots representing low-, medium- and high-energy X-rays, indicates there are relatively few X-ray sources in the pillars and suggests the Eagle Nebula is past its star-forming prime, said Linsky.
Linsky and colleagues from West Chester University in Pennsylvania, the University of Exeter in England and the University of Arizona analyzed visual and infrared emissions from the pillars to identify E42, the Sun-like proto-star. E42 is located in the left pillar on the right edge of a node jutting out to the right about two-thirds of the way down the pillar.
"We think this is a very, very early version of our own Sun," said Linsky.
E42 is one of 73 EGGs discovered in the Pillars of Creation in 1996 with the Hubble Space Telescope by Arizona State University astronomer Jeff Hester and his team. While 11 of the EGGs have been determined to contain infant stellar objects, only four are massive enough to form a star. Of those, E42 is the only one that has a Sun-sized mass, said Linsky.
"The four proto-stars that we have identified on the edges of the pillars are probably the youngest stars ever imaged by astronomers," Linsky said.
While Linsky and his team used Chandra to zero in on more than 1,100 hotter, more mature stars in the Eagle Nebula, neither E42 nor the other three EGGs believed massive enough to form stars were observed to be emitting any X-rays, he said. "The results indicate young, evolving stars like E42 have not yet developed the magnetic structures needed to produce X-rays," he said.
Earth’s Sun is thought to have formed some 5 billion years ago after clouds of dust and gas were seared by ultraviolet radiation and pounded by shockwaves from one or more supernovae explosions, Linsky said. "The Sun was likely born in a region like the Pillars of Creation because the chemical abundances in the solar system indicate that a supernova occurred nearby and contributed its heavy elements to the gas of which the Sun and the planets formed." Studying E42 and how it continues to develop will help astronomers understand how our own Sun formed and how it affected the environment of the early solar system.
A January 2007 study by an astronomy team from France suggested the pillars were toppled some 6,000 years ago by a nearby supernova explosion, as evidenced by a glowing cloud of scorched dust adjacent to the pillars. Since the pillars are roughly 7,000 light years away, the French team contends they will still be visible from Earth as "ghost images" for another thousand years or so.
"My guess is that the shock wave from the supernova may have been far enough away so that E42 and some of the other stars may have survived," said Linsky. "But I guess we will have to wait another thousand years or so to get the answer."
Other astronomy team members collaborating with Linsky included Marc Gagne and Anne Mytyk of West Chester University, Mark McCaughrean of the University of Exeter and Morten Andersen of the University of Arizona. A paper on the subject was published in the Jan. 1 issue of the Astrophysical Journal. The orbiting Chandra X-Ray Observatory was deployed by NASA aboard a space shuttle and boosted into high Earth orbit in July 1999 to study the origin, evolution and destiny of the universe.