A new theory presented by fluid dynamics experts at the University of California, Berkeley, shows
how "zombie vortices" help lead to the birth of a new star.
A team led by computational physicist Philip Marcus, a professor in the Department of Mechanical
Engineering.shows how variations in gas density lead to instability, which then generates the whirlpool-like
vortices needed for stars to form.
Astronomers accept that in the first steps of a new star's birth, dense clouds of gas collapse into clumps
that, with the aid of angular momentum, spin into one or more Frisbee-like disks where a protostar starts to form.
A disk of dust and proto-planets around the star Beta Pictoris. Credits: Jon Lomberg
However, for the protostar to grow bigger, the spinning disk needs to lose some of its angular momentum so
that the gas can slow down and spiral inward onto the protostar. Once the protostar gains enough mass, it
can kick off nuclear fusion.
The leading theory in astronomy relies on magnetic fields as the destabilizing force that slows down the disks.
One problem in the theory has been that gas needs to be ionized, or charged with a free electron, in order
to interact with a magnetic field but there are regions in a protoplanetary disk that are too cold for
ionization to occur.
"Current models show that because the gas in the disk is too cool to interact with magnetic fields, the
disk is very stable," said Marcus.
"Many regions are so stable that astronomers call them dead zones - so it has been unclear how disk matter
destabilizes and collapses onto the star."
The researchers said current models also fail to account for changes in a protoplanetary disk's gas
density based upon its height.
"This change in density creates the opening for violent instability," said study co-author Pedram Hassanzadeh,
who did this work as a UC Berkeley Ph.D. student in mechanical engineering.
Illustration of a protoplanetary disk based upon observations from the Keck II telescope. Image courtesy of W. M. Keck Observatory
"When they accounted for density change in their computer models, 3-D vortices emerged in the protoplanetary
disk, and those vortices spawned more vortices, leading to the eventual disruption of the protoplanetary
disk's angular momentum."
"Because the vortices arise from these dead zones, and because new generations of giant vortices march
across these dead zones, we affectionately refer to them as 'zombie vortices,'" said Marcus.
"Zombie vortices destabilize the orbiting gas, which allows it to fall onto the protostar and
complete its formation."
"Other research teams have uncovered instabilities in protoplanetary disks, but part of the problem
is that those instabilities required continual agitations," said Klein.
"The nice thing about the zombie vortices is that they are self-replicating, so even if you start with
just a few vortices, they can eventually cover the dead zones in the disk."
Enigmatic Rare And Very Hot Stars Of Dr. Wolf And Mr. Rayet -
Still A Fascinating Subject!
The universe is changing and stars are changing as well, even if they appear static and predictable every night.
Wolf-Rayet stars remain a fascinating subject of research for astronomers even if the first of them were discovered more than 140 years ago.
In the summer of 1867, French astronomers Charles Wolf and Georges Rayet observed for the first time three strange
objects during a visual spectroscopic study of stars in the constellation Cygnus at the Observatoire de Paris, France.
Subscribe To Our Space, Astronomy, Astrophysics, Earth and Xenology News!
Grab the latest RSS feeds right to your reader, desktop or mobile phone.
Space-Time Crystal Computer That Can Outlive Even The Universe Itself!
It may seem strange to think something can survive even the death of the Universe, but that could actually be possible as a result of the laws of quantum physics.
Scientists are now suggesting a new blueprint for a device, known as a time crystal, that can theoretically continue to function as a
Most Alien World We Can Only Imagine
This is not an alien world, anyone of us will ever be able to visit.
It's not very far away, only about 40 light years from Earth, but it circles dangerously close to a stellar inferno, completing
one orbit in only 18 hours. The alien planet named "55 Cancri e" is 26 times closer to its parent star than Mercury is to the Sun.
The temperature on the surface of 55 Cancri e is estimated to be as high as 2,700 degrees Celsius.
X-ray 'Echoes' Will Help Probe
A Supermassive Black Hole's Surroundings
Most big galaxies host a big central black hole containing millions of times the sun's mass. When matter streams toward one of
these supermassive black holes, the galaxy's center lights up, emitting billions of times more energy than the sun.
For years, astronomers have been monitoring such "active galactic nuclei" (AGN) to better understand what happens on the brink of a monster black hole.
Mysterious X-Rays From Jupiter Near The Poles
Although there had been prior detections of X-rays from Jupiter with other X-ray telescopes, no one expected that the sources of the
X-rays would be located so near the poles.
The X-rays are thought to be produced by energetic oxygen and sulfur ions that are trapped in Jupiter's magnetic field and crash into its atmosphere.
Record-Breaking Radio Waves From Ultra-Cool Brown Dwarf
Flaring radio emissions from an ultra-cool star, not much warmer than the planet Jupiter, have been discovered by Penn State astronomers
using the world's largest radio telescope, at Arecibo, Puerto Rico.
This is by far the coolest brown dwarf yet detected at radio frequencies...
First X-Rays From The Remains Of A Supernova
Observed Over 50 Years Ago
Astronomers have detected X-rays from the remains of a supernova in the constellation Hydra, first seen from Earth over 50 years ago.
While detected in the radio and optical for decades, the supernova SN 1957D, the fourth one detected
in the year 1957, did not appear in previous X-ray images.