M16, Eagle Nebula, NGC 6611
Although NASA's Hubble Space Telescope has taken many breathtaking
images of the universe, one snapshot stands out from the rest: the
iconic view of the so-called "Pillars of Creation." The jaw-dropping
photo, taken in 1995, revealed never-before-seen details of three giant
columns of cold gas bathed in the scorching ultraviolet light from a
cluster of young, massive stars in a small region of the Eagle Nebula,
or M16.
Though such butte-like features are common in star-forming regions,
the M16 structures are by far the most photogenic and evocative. The
Hubble image is so popular that it has appeared in movies and
television shows, on tee-shirts and pillows, and even on a postage
stamp.
And now, in celebration of its 25th anniversary, Hubble has revisited
the famous pillars, providing astronomers with a sharper and wider
view. As a bonus, the pillars have been photographed in near-infrared
light, as well as visible light. The infrared view transforms the
pillars into eerie, wispy silhouettes seen against a background of
myriad stars. That's because the infrared light penetrates much of the
gas and dust, except for the densest regions of the pillars. Newborn
stars can be seen hidden away inside the pillars. The new images are
being unveiled at the American Astronomical Society meeting in Seattle,
Washington.
Although the original image was dubbed the Pillars of Creation, the
new image hints that they are also pillars of destruction. "I'm
impressed by how transitory these structures are. They are actively
being ablated away before our very eyes. The ghostly bluish haze around
the dense edges of the pillars is material getting heated up and
evaporating away into space. We have caught these pillars at a very
unique and short-lived moment in their evolution," explained Paul Scowen
of Arizona State University in Tempe, who, with astronomer Jeff
Hester, formerly of Arizona State University, led the original Hubble
observations of the Eagle Nebula.
The infrared image shows that the reason the pillars exist is because
the very ends of them are dense, and they shadow the gas below them,
creating the long, pillar-like structures. The gas in between the
pillars has long since been blown away by the ionizing winds from the
central star cluster located above the pillars.
At the top edge of the left-hand pillar, a gaseous fragment has been
heated up and is flying away from the structure, underscoring the
violent nature of star-forming regions. "These pillars represent a very
dynamic, active process," Scowen said. "The gas is not being passively
heated up and gently wafting away into space. The gaseous pillars are
actually getting ionized (a process by which electrons are stripped off
of atoms) and heated up by radiation from the massive stars. And then
they are being eroded by the stars' strong winds (barrage of charged
particles), which are sandblasting away the tops of these pillars."
When Scowen and Hester used Hubble to make the initial observations
of the Eagle Nebula in 1995, astronomers had seen the pillar-like
structures in ground-based images, but not in detail. They knew that
the physical processes are not unique to the Eagle Nebula because star
birth takes place across the universe. But at a distance of just 6,500
light-years, M16 is the most dramatic nearby example, as the team soon
realized.
As Scowen was piecing together the Hubble exposures of the Eagle, he
was amazed at what he saw. "I called Jeff Hester on his phone and said,
'You need to get here now,'" Scowen recalled. "We laid the pictures
out on the table, and we were just gushing because of all the
incredible detail that we were seeing for the very first time."
The first features that jumped out at the team in 1995 were the
streamers of gas seemingly floating away from the columns. Astronomers
had previously debated what effect nearby massive stars would have on
the surrounding gas in stellar nurseries. "There is only one thing that
can light up a neighborhood like this: massive stars kicking out
enough horsepower in ultraviolet light to ionize the gas clouds and make
them glow," Scowen said. "Nebulous star-forming regions like M16 are
the interstellar neon signs that say, 'We just made a bunch of massive
stars here.' This was the first time we had directly seen observational
evidence that the erosionary process, not only the radiation but the
mechanical stripping away of the gas from the columns, was actually
being seen."
By comparing the 1995 and 2014 pictures, astronomers also noticed a
lengthening of a narrow jet-like feature that may have been ejected
from a newly forming star. The jet looks like a stream of water from a
garden hose. Over the intervening 19 years, this jet has stretched
farther into space, across an additional 60 billion miles, at an
estimated speed of about 450,000 miles per hour.
Our Sun probably formed in a similar turbulent star-forming region.
There is evidence that the forming solar system was seasoned with
radioactive shrapnel from a nearby supernova. That means that our Sun
was formed as part of a cluster that included stars massive enough to
produce powerful ionizing radiation, such as is seen in the Eagle
Nebula. "That's the only way the nebula from which the Sun was born
could have been exposed to a supernova that quickly, in the short
period of time that represents, because supernovae only come from
massive stars, and those stars only live a few tens of millions of
years," Scowen explained. "What that means is when you look at the
environment of the Eagle Nebula or other star-forming regions, you're
looking at exactly the kind of nascent environment that our Sun formed
in."
CONTACT
Felicia Chou
NASA Headquarters, Washington, D.C.
202-358-0257
felicia.chou@nasa.gov
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
Source: HubbleSite
