A dramatic drop in Eta Carinae's stellar winds
could herald a bright future.
J. Morse, Univ. Colorado/NASA
After a huge outburst of gas that occurred more than 150 years ago,
it has largely been hidden by a dense cloud of dust —
a strong indicator of sporadic eruptions.
WHY HAVE THE STELLAR WINDS DROPPED?
Now, Eta Carina, which sits in our part of the Milky Way
some 2,300 parsecs (7,500 light years) from the Sun,
is puzzling researchers and theorists all over again.
A US-based team has recorded a steep,
inexplicable drop in its stellar wind —
the outflow of gas from the star —
measured as a change
in the emission lines, or lines in the spectrum caused by
the emission of light at particular wavelengths.
UNIVERSITY OF MINNESOTA RESEARCHERS
Researchers from the
University of Minnesota in Minneapolis
recorded the dip from the eruptive,
luminous variable star using data
from the Gemini South Telescope in Chile
and the Hubble Space Telescope.
Their results are detailed in a paper accepted for publication
in Astrophysical Journal Letters1.
"The collapse in the emission lines seemed almost too rapid
and drastic to believe,"
says Kris Davidson,
an astrophysicist at the
University of Minnesota and a co-author of the latest study.
In January, Davidson's
colleague and the study's lead author
Andrea Mehner
first noticed the effect in data from
the Gemini South Telescope.
The team then confirmed Mehner's findings through
observations using Hubble.
STONY BROOK UNIVERSITY IN NEW YORK
GEORGIA INSTITUTE OF TECHNOLOGY IN ATLANTA
Their findings have been independently verified by astronomers
affiliated with
Stony Brook University in New York and
the Georgia Institute of Technology in Atlanta.
"Eta Carina is more than a variable star," says Davidson,
"it's just nuts."
SUPERNOVA IMPOSTER
The root of Eta Carina's oddness lies in
the supernova-like eruption
event that began in the late 1830s and lasted
for some 20 years.
Lines in the emission spectrum of Eta Carinae
have collapsed to
only a third of their original strength in a decade.
A. Mehner, University of Minnesota
UNIVERSITY OF CALIFORNIA BERKELEY
Nathan Smith,
a postdoctoral researcher in astronomy at
the University of California, Berkeley,
who was not involved with
the observations, says that
Eta Carina is a "key object for understanding the
instability of the most massive stars".
Smith adds that these eruptions may provide glimpses of what
to expect from the Universe's first stars,
called population III stars.
Meanwhile, if Eta Car's current trend of decreasing winds
continues, in a decade it will have very nearly emerged
from its cocoon of dense gaseous outflow.
That would return it to the state observed by Halley some
300 years ago, when it was seen as a hot, blue star,
now known to have been of spectral class O.
The Minnesota team notes that this would
finally enable contemporary
observations of the radius and surface
temperature of Eta Car,
which is estimated to have the mass of
well over 100 Suns.
http://www.nature.com/news/2010/100615/full/news.2010.295.html
STRANGE LIGHT IN THE SKY
I wanted to go over with you
a strange discovery so we can
keep our eye on developments and be aware t
hat something is going on.
Of course we are anticipating the arrival of the light from
the center eye of Supernova 1987a.
Now look at this.
A star named Eta Carinae that has dimmed for decades is
now tripling its energy mostly in invisible light.
Note, What puzzles astronomers is that Eta Carinae
was not supposed to do this.
This statement is from
Kris Davidson,
astrophysicist
from the University of Minnesota.
"Occasionally something happens in astronomy
hat is so bewildering
that it makes astronomers nervous.
This is weird, we don't understand."
Here is something weird tripling its energy in invisible light
and this is what the news release from CNN says.
"The star about 7500 light years from earth
is among the most
massive and energetic in the known universe.
The energy it emits, most of it invisible radiation is up to
5 times more powerful then the sun."
Now look at this
Eta Carinae was a routine part of the sky
in the Southern Hemisphere
until the 1840’s when it was observed to erupt
with a massive outflow of energy.
For awed watchers on Earth it was as if a light bulb in the
heavens was suddenly turned on.
It became very very bright for 20 years .
Its brilliance matched a Supernova and then it became
dimmer and dimmer until it faded from view.
Astronomers learned that it had been
blocked by an immense
cloud of dust so they theorized that it
would become visible again
as the dust cleared.
Astronomers expected the star to slowly brighten until
sometime in the next century.
But Eta Carinae surprised the experts.
Over a matter of months the star was seen spewing out vast
amounts of energy in all bands of the electromagnetic spectrum.
Astronomers had not expected such an energy burst for
many decades and it was expected that the star would first emit
cooler radiation sort of as a warning of coming violence.
That did not happen.
Consider This From Astrophysicist Kris Davidson
There are about 6000 stars in the sky visible to the naked eye.
We understand them all with the sole exception of
Eta Carinae.
There is no theoretical explanation for it.
Theorists believe it may create a hypernova a stellar explosion
many times more powerful then a supernova.
It could then start spewing gamma radiation in short waves
that might equal the entire energy of the sun.
Such bursts might even be hazardous at 7500 light years,
the distance to Earth
So the Sky King is obviously placing things in position.
As I have tried to share with anyone that would listen,
strange and powerful things are coming down upon the earth
that will totally change the structure of civilization as you know it.
I am providing this documentation of what is about to happen even
though the scientists who are watching really do not know when or how.
The word ETA means 7th.
The word Carinae means keel as a ship or the breast of a bird
TO RETURN TO THE HIDDEN MEANINGS HOME PAGE
MYSTERIOUS ERUPTIONS
Huge stars like Eta Car can erupt for reasons that Davidson
says are about 95% "mysterious".
One theory is that once these massive stars near the end of their short lives —
after some 2 million to 3 million years —
perturbations in their cores may set off sporadic
'supernova impostor' eruptions.
Eta Carina, which is five million times more luminous than
the Sun, was the first such impostor detected,
although about a dozen are known to astronomers today.
During its mid-nineteenth-century eruption,
Eta Carina lost about ten times the mass of the Sun.
Although this loss was equivalent to only 10% of its mass,
the star's outer 50% was ejected.
As a result, the star has still not returned to thermal
and rotational equilibrium.
Since 1858, it has been observed only as a massive gaseous outflow,
losing the equivalent of one Jupiter-mass in gas per year.
HIDDEN BEHIND THE ANGELS WINGS
"We still can't see the star itself," says Davidson,
"but only an opaque dense wind outflow surrounded by muck —
really bright ejecta."
Before 1700, Davidson notes that Eta Carina was a fourth-magnitude star,
recorded by astronomer Edmond Halley and only a few others.
By 1843, it was almost as bright as Sirius before suddenly fading in 1858.
"After a supernova impostor explosion," says Davidson,
"the star is in a state [of disequilibrium] that none
of the theorists' computer codes are set up to deal with."
HIDDEN BEHIND THE ANGELS WINGS
"We still can't see the star itself," says Davidson,
"but only an opaque dense wind outflow surrounded by muck —
really bright ejecta."
Before 1700, Davidson notes that Eta Carina was a fourth-magnitude star,
recorded by astronomer Edmond Halley and only a few others.
By 1843, it was almost as bright as Sirius before suddenly fading in 1858.
"After a supernova impostor explosion," says Davidson,
"the star is in a state [of disequilibrium] that none
of the theorists' computer codes are set up to deal with."