Astronomers unravel the mystery of the 'Dragon's Egg' nebula

Two large stars residing inside a spectacular cloud of gas and dust nicknamed the “Dragon’s Egg” nebula have presented a puzzle to astronomers.

Two large stars residing inside a spectacular cloud of gas and dust nicknamed the "Dragon's Egg" nebula have presented a puzzle to astronomers. One of them has a magnetic field, as does our sun. Its companion does not. And such massive stars are not usually associated with nebulae.

Researchers now appear to have resolved this mystery while also explaining how the relatively few massive stars that are magnetic got that way. Blame it on stellar fratricide, they said. In this case, the bigger star apparently gobbled up a smaller sibling star, and the mixing of their stellar material during this hostile takeover created a magnetic field.

"This merger was likely very violent. When two stars merge, material can be thrown out, and this likely created the nebula we see today," said Chile-based European Southern Observatory astronomer Abigail Frost, lead author of the study published on Thursday in the journal Science.

Computer simulations previously had predicted that the blending of stellar material during such a merger could create a magnetic field in the combined star born in this process.

"Our study is the observational smoking gun confirming this scenario," said astronomer Hugues Sana of KU Leuven in Belgium, the study's senior author.

These two stars - gravitationally bound to each other in what is called a binary system - are located in our Milky Way galaxy about 3,700 light-years from Earth in the constellation Norma. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

The researchers used nine years of observations by the Chile-based Very Large Telescope.