Astronomers observe a dying red giant star's final act

March 17, 2017, University of California, Los Angeles
Molecular gas forms a spiral pattern around the red giant star LL Pegasi. Credit: ALMA, Hyosun Kim

An international team of astronomers has observed a striking spiral pattern in the gas surrounding a red giant star named LL Pegasi and its companion star 3,400 light-years from Earth, using a powerful telescope in northern Chile called Atacama Large Millimeter/submillimeter Array, or ALMA.

"What we are seeing in splendid detail with these observations is the final act of a dying red giant star, as it sheds most of its gaseous bulk in a strong, outflowing wind," said study co-author Mark Morris, UCLA professor of physics and astronomy.

After comparing their telescopic observations with computer simulations, the astronomers concluded that a highly elliptical orbit is responsible for the shape of the gaseous emissions surrounding this system.

The research appears in the journal Nature Astronomy and is the cover story of the March issue.

"Because of the orbital motion of the mass-losing red giant, the cold molecular gas constituting the wind from that star is being spun out like the sprays of water from a rotating garden sprinkler, forming the outflowing pattern of spiral shells," Morris said.

ALMA, a powerful international facility operated cooperatively by many countries around the world including the United States, measures extremely short wavelength radio emission. Using this unique instrument, the scientists were able to create a three-dimensional image of the emission from molecules ejected from LL Pegasi and which then form a spiral pattern caused by the presence of the orbiting .

3-D visualization of LL Pegasi, starting from a Hubble Space Telescope image . Credit: University of California, Los Angeles

The images, which show many complete revolutions of the spiral pattern, offer clues about the dynamics of the binary system over a period of 5,000 years.

"This unusually ordered system opens the door to understanding how the orbits of such systems evolve with time as one of the loses most of its mass," Morris said.

Molecular gas emission from LL Pegasi . Credit: University of California, Los Angeles

Explore further: ALMA spots surprising spiral structure, reveals secrets of a dying star

More information: Hyosun Kim et al. The large-scale nebular pattern of a superwind binary in an eccentric orbit, Nature Astronomy (2017). DOI: 10.1038/s41550-017-0060

Related Stories

Recommended for you

6 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (8) Mar 17, 2017
Due to astrophysicists utter ignorance of real plasma physics the must rely on their imaginary conjecture of lawn sprinklers as being the explanation of what is otherwise an ubiquitous phenomena in plasmas, the spiral...
Captain Stumpy
4.3 / 5 (6) Mar 18, 2017
@nazi sympathizing eu pseudoscience conspiracy nut
Due to astrophysicists utter ignorance of real plasma physics
repeating this lie doesn't make it more true
http://www.pppl.gov/about

that is just one plasma physics lab which specifically proves your idiot comment is a blatantly oft-repeated false claim

you can't provide any reputable peer reviewed source material that gives a demonstration or better theory to show the mechanism of your eu nut-job crank theory bullsh*t flavour of the week excuse so why keep repeating it?

Hoping to gain credibility be repetition when people stop pointing out you're a liar?
DeliriousNeuron
1 / 5 (6) Mar 20, 2017
Give up already Captain Stupid! You're like a scratched record posting the same irrelevant things. I've never seen you actually contribute anything here besides your same old re-worded defence posts.
Whatever it is you're trying to prove is not working. Defending a nearly dead Era in physics and looking like a psycho ass doing it is humorous and will be entertaining for future readers of phys.org, its time to move on.
Captain Stumpy
5 / 5 (3) Mar 20, 2017
@idiot delerious pseudoscience troll
Give up already delerious idiot troll! You're like a scratched record posting the same irrelevant things. I've never seen you actually contribute anything here besides your same old re-worded blatant lies and eu religion posts.

Whatever it is you're trying to prove is not working. Defending a fully dead and debunked physics based on religious beliefs and looking like a psycho ass doing it is humorous and will be entertaining for future readers of phys.org, its time to move on.

shall i remind you that the above link refutes the claims of all you eu nutjobs?
the fact is - science isn't about what you believe to be true
it doesn't care what you believe

it's about evidence, repeatability and validation
three things you have never once brought to the table to explain any of your eu crap

691Boat
5 / 5 (3) Mar 20, 2017
Due to astrophysicists utter ignorance of real plasma physics the must rely on their imaginary conjecture of lawn sprinklers as being the explanation of what is otherwise an ubiquitous phenomena in plasmas, the spiral...

Please describe with credible sources the plasma mechanism we are actually seeing, if it is EU supported. What is causing the wind they are seeing? Why is this wind actually being discharged from the red giant in question? Why does the wind seem to be emitted from a single point on the source star? What effect does the partner star have on said "ubiquitous phenomena"?
Thanks in advance!
Da Schneib
5 / 5 (2) Mar 20, 2017
@691, your observation that the wind seems to be emitted from a single point is quite relevant. If we are lucky @RNP and @IMP-9 who are both quite skilled in astrophysics will weigh in on this. The two possibilities I see are
a) It's due to asymmetry in the red giant itself, driven by the asymmetric gravity imposed by the companion star, or
b) It's due to the asymmetric gravity itself, concentrating emissions from all over the red giant in the area most affected by the companion star's gravity.

Or both. That's the most interesting (and complicated) conjecture.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.