An image of the biggest star jet made of hydrogen and nitrogen emissions of Sanduleak’s star taken with the Magellan-Clay Telescope at the Las Campanas Observatory in Chile.
Credit: R. Angeloni et al. Pontificia Universidad Cat´olicade, Chile
SYDNEY: A star shooting matter in a jet stretching over 400 trillion km has been found in the Large Magellanic Cloud, a nearby galaxy to Earth.
The star jet covers about 10 times the distance between our Solar System's Sun and nearest neighbouring star proxima Centauri, and is more than 70,000 times the distance between Pluto and the Sun.
"What's interesting here is that we found a huge structure," said astronomer Francesco Di Mille from the Australian Astronomical Observatory in Sydney, and co-author of the study published in The Astrophysical Journal Letters. "We don't know if there are other jets like this in the galaxy, so we're just at the beginning of this exciting discovery."
Biggest star jet from Sanduleak's star
The massive jet of material is coming from Sanduleak's star in the Large Magellanic Cloud, which was first discovered by American astronomer Nicholas Sanduleak in 1977. It is suggested that Sanduleak's star is actually a symbiotic star - two stars closely orbiting one another.
"We are still investigating the jet but we think it's possible that we are dealing with a double star, a binary star," said Di Mille. "It's called a symbiotic star because there is a giant star that blows material onto a compact star."
Researchers think that Sanduleak is a binary star with a smaller white dwarf star, which is at the end of its life, orbiting a larger red giant star at an earlier stage of its life.
"At that stage [the red giant] expands a great deal, so its envelope is reaching far enough out, diffusely enough, that the white dwarf can grab some of it with its gravity [and] turn it into a disc of material," said astronomer Matthew Colless from the Australian Astronomical Observatory, who was not involved in the research. "It's that combination of an accretion disc and the magnetic field of the white dwarf that produces the jets like this one we see."
The biggest star jet found
Di Mille and his team used the Magellan Telescopes at the Las Campanas Observatory in Chile to study binary stars outside of our own galaxy. "We started this study on the symbiotic stars in the Magellanic Cloud for the simple reason that we know the distance," said Di Mille.
Di Mille concentrated on a small part of the red wavelength range - which is useful in imaging the jets of the symbiotic stars - by using filters in the telescope. "We know that in the galaxy there are nebulae around these objects, but we were expecting something small," said Di Mille. "But in the image the structure was big [and] when you measure the size you have the largest jet."
Aside from being over 14 parsecs long (over 400 trillion km), Di Mille and his team were also able to calculate that this star jet has been streaming out of Sanduleak's star for around 10,000 years at a speed of about 1500km per second (5 million km per hour)
"We measured the velocity at the top of the jet and we measured the distance from the central source [and] in simple calculations we thought how long would this jet take, at this velocity, to reach this point," said Di Mille.
The future of Sanduleak's star
The results of Di Mille's research have challenged previous theories about star jets, which may not be adequate to explain such a powerful structure. "It's important because it shows that the jets that can be produced by stars can be very much bigger than people had anticipated, so clearly the process can be much more powerful," commented Colless. "It means that theorists will have to go back and re-examine their models and determine whether they can be adjusted to produce something quite as large as this."
Di Mille added, "We have to confirm the nature of the central source. We're still lacking the smoking gun for symbiotic stars, because we still can't see the stellar components of these objects."
Colless agreed that the star jet discovery has sparked more questions than it answered and said, "any number of telescopes and satellites will be turned to study this object again in order to get more information. One of the things that they'll be most interested in is whether the object at the heart of it really is a symbiotic star as is believed and trying to get good evidence for that."
