Giant star-jet astounds astronomers

Sanduleak's star

Sanduleak's star and the jet of matter shooting out from it at more than 5 million kilometres per hour. The jet is now 400 million million kilometres long.

  • Star shooting out jet of material 400 million million km long
  • Thought to occur due to interaction between two stars
  • Located in the Large Magellanic Cloud galaxy

ASTRONOMERS HAVE FOUND a star spitting matter into a “jet” that stretches for more than 400 million million kilometres across space.

That’s about ten times the distance between the Sun and its nearest neighbouring star (proxima Centauri).

It’s the biggest jet known from a star, and “challenges our current understanding,” said Dr Francesco Di Mille (Australian Astronomical Observatory and the University of Sydney), a member of the team that made the finding.

Theoretical models don’t deal with it, he said, “simply because nobody would ever have bet that such a giant stellar jet could exist”.

In a galaxy not so far away

The star making the jet is called Sanduleak’s star, having been discovered by astronomer Nicholas Sanduleak in 1977.

Sanduleak noted that the star varied in brightness, but didn’t see the jet.

That’s not surprising. The star is shrouded by dust, and it’s not even in our Galaxy—it’s in a small neighbouring galaxy called the Large Magellanic Cloud, about 160 thousand light-years away.

Finding the jet fell to Dr Di Mille’s team, led by Italian astronomer Rodolfo Angeloni (Pontificia Universidad Católica de Chile), which turned the 6.5-m Magellan Telescopes in Chile on the star.

Magellan Telescopes

Observations were made with the Magellan Telescopes in Chile.

Outburst 10,000 years old

Dust surrounding the star makes it hard to tell exactly what’s going on, but it seems that actually two stars are involved: a red giant and a white dwarf, tangoing closely.

The red giant’s hot “breath”—transferred matter—curls into a belt around the white dwarf’s belly. From time to time a jet shoots up and down from this disc of material, along the star’s axis of rotation.

Artist's impression of a system like Sanduleak's star

An artist's impression of a system like Sanduleak's star—a red giant star transferring matter onto a white dwarf star.

Astronomers have worked out that the current outburst has been going on for about ten thousand years, and that the material in the jet is travelling at more than 5 million kilometres per hour (1,500 km per second).

“Because we know the distance to this star we’ll be able to make good estimates of most of the jet’s properties,” Dr Di Mille said.

“It will be the best test-case for understanding jets from stars.”

The researchers have published their finding in The Astrophysical Journal Letters.

Adapted from information issued by AAO. Magellan Telescopes image courtesy Francisco Figueroa. Sanduleak’s star image courtesy R. Angeloni et al. Artist’s impression courtesy Dana Berry (STScI).

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  1. Jonathan Nally says:

    Hi Michal,
    Nicholas Sanduleak was a US astronomer who did lots of work on star surveys, including producing groundbreaking catalogues of stars in the Small and Large Magellanic Cloud galaxies, which are neighbours of the Milky Way. So yes, one of the stars in his catalogue was the progenitor of SN 1987A in the Large Magellanic Cloud (LMC). But “Sanduleak’s star”, although also in the LMC, is a different one. It has another, weirder, name too — LMC Anonymous! More (technical) info here: http://adsabs.harvard.edu/full/1989ApJ…341..367M
    http://iopscience.iop.org/2041-8205/743/1/L8;jsessionid=AE727DB9B479B972041DC4E570811AF3.c1
    Cheers,
    Jonathan

  2. Michal says:

    I’m a little confused. I thought that “Sanduleak’s star” (Sanduleak -69° 202) was responsible for SN 1987A but that obviously must be a different star.