MessageToEagle.com - Astronomers from Center for Astrophysics of the University of Porto, Portugal
and Oskar Klein Centre, Stockholm University, Sweden come up with new findings regarding one of the most studied
objects - the dwarf galaxy I Zw 18.
CAUP Astronomer Polychronis Papaderos, and Göran Östlin (Oskar Klein Center, U. Stokholm), used the Hubble Space
Telescope (HST) to get extremely accurate observations of this galaxy and data with unprecedented resolution and sensitivity.
The results led the scientists to the conclusion that this enigmatic blue compact dwarf might force astronomers to review
current galaxy formation models and much of what is known about galaxy formation and evolution might need substantial revision.
Composite image of 3 filters, in visible and infrared light, of the I Zw 18 region. Gas sorrounding the two stellar cores is clearly visible. In the upper right corner, you can also see the blue dwarf I Zw 18 C.
Credit: Polychronys Papaderos (CAUP)/Göran Östlin (Oskar Klein Center, U. Stockholm)
The dwarf galaxy I Zw 18 is, one of the poorest in heavy elements, located only 59 million light years away.
It's among those that have strong star forming activity.
Analysis of these data revealed an extended gas halo surrounding this galaxy, 16 times larger than the
star component of the galaxy, and without any stars.
This halo is the result of huge amounts of energy generated by the starburst this galaxy is going through.
The energy heats and disturbs I Zw 18's cold gas, which ends up emitting an amount of light comparable to what's
being emitted by the stellar component.
This emission is designated nebular emission.
"This is ground-breaking work because it provides the first observational proof that, in the early Universe,
young galaxies that underwent starbursts must have been surrounded by a huge halo of nebular emission," Papaderos said.
"This extended nebular halo results from the cumulative energetic output from thousands of massive stars exploding
as supernovae, shortly after their formation."
So far, in distant galaxies where it's not possible to reach resolutions high enough in order to distinguish between
nebular and star emission, it was assumed that the gas occupied the same region as the stars and stars were responsible
for emitting most of the light.
The study showed that galaxies undergoing starbursts, similar to I Zw 18, might not obey this rule.
I Zw 18 region, with stellar distribution contours. Credit: Polychronys Papaderos (CAUP)/Göran Östlin
(Oskar Klein Center, U. Stockholm)
This result might lead to substantial corrections in a lot of the work being developed in cosmology and extragalactic
astronomy. An example is the estimate of star mass in a galaxy, which is calculated from the galaxies total luminosity.
But, as these results shows, up to 50% of that luminosity might originate in nebular, and not star, emission.
Another result from this research shows that, according to Papaderos, "the distribution of nebular emission might
be misinterpreted as a stellar disk. These galaxies, still in early stages of formation, might thus be wrongly
classified as fully formed galaxies" (such as spirals or ellipticals), a classification mistake that might have
happened in many past studies to determine galaxy evolution in the early Universe.
These results are also of importance for our understanding of galaxy formation, because the team concluded that
I Zw 18 is extremely young, with most stars younger than 1 billion years.
So this galaxy is currently undergoing the dominant phase of its formation, much like the ones formed shortly after the Big Bang.
Listen To The Song Of The Sun
The sun gives off more than just heat and light. One astronomer thinks it makes music, too.
From here on Earth, that great ball of fire in the sky appears to be perfectly round. But closer study reveals storms and
giant gaseous eruptions covering the surface of the sun. Now one scientist has found a way to translate those eruptions into strangely beautiful music.
Astronomical Mystery - Tremendous Explosion And Appearance Of Odd Rings
Twenty five years ago, on 1987 February 23, the brightest supernova of modern times was observed in the Large Magellanic Cloud.
The collision occurred at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow.
Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material...
Remarkable Extragalactic Object
These objects are very rare. A discoverer of one of them even named it a "pathological galaxy".
Sixty one years ago, an American astronomer, Arthur Allen Hoag (1921-1999) discovered a remarkable extragalactic object. He described
it as a "perfect halo" surrounding a diffuse nucleus.
Gigantic Black Hole At The Centre Of The Milky Way Eats Asteroids
The supermassive black hole at the centre of the Milky Way "eats" asteroids on a regular basis, concluded using the American Chandra X-ray Observatory.
Over the course of several years, Chandra discovered a series of X-ray blasts with a frequency of approximately one a day from the black hole Sagittarius A* (Sgr A*).
Earth's Clouds Are Dropping - Something Important Is Happening
New research shows Earth's clouds are getting little lower, about one percent on average.
According to scientists this indicates that something quite important might be going on.
The results have potential implications for future global climate.
Abnormal Star Discovered In The 'Forbidden Zone'
A team of astrophysicists from Germany, France and Italy have discovered in the constellation Leo is an old star.
The star's existence raised at once many questions for scientists.
The object is definitely not as its "contemporaries" that appeared immediately after the Big Bang event.
The Eyes Of A Future Alien Astronomer - What Will They See?
Have you ever wondered what the Universe will look like for a future alien astronomer?
It will in fact be entirely different from what it is today.
One trillion years from now, an alien astronomer in our galaxy will have great difficulties figuring out how the universe began.
The Milky Way will have merged with the Andromeda galaxy to form the Milkomeda galaxy. Many of its stars, including our Sun, will have burned out.
Violent Dragon Clash Billions Of Years Ago
NGC 5907 is sometimes called the "Splinter" or Knife Edge Galaxy because of its unusual appearance.
It is a spiral galaxy lying in the Dragon constellation,
about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.
Researchers Developed A Very Accurate Map Of Milky Way's Magnetic Field
The Milky Way is hard to map because we are sitting on the edge of the galaxy looking through it.
However, we know that spiral galaxies like the Milky Way have magnetic fields that follow a particular pattern so we were able
use polarised light to map the magnetic fields...
First Discovered Carbon-Rich Planet: Could It Harbor Life?
WASP-12b is the first carbon-rich world ever observed. It is an extremely hot and large gas giant orbiting another star and it has unusual amount of carbon.
Carbon is a common component of planetary systems and a key ingredient of life on Earth.
Does it mean some kind of life might exist on WASP-12b?
MessageToEagle.com - Astronomers from Center for Astrophysics of the University of Porto, Portugal
and Oskar Klein Centre, Stockholm University, Sweden come up with new findings regarding one of the most studied
objects - the dwarf galaxy I Zw 18.
The sun gives off more than just heat and light. One astronomer thinks it makes music, too.
From here on Earth, that great ball of fire in the sky appears to be perfectly round. But closer study reveals storms and
giant gaseous eruptions covering the surface of the sun. Now one scientist has found a way to translate those eruptions into strangely beautiful music.
Twenty five years ago, on 1987 February 23, the brightest supernova of modern times was observed in the Large Magellanic Cloud.
These objects are very rare. A discoverer of one of them even named it a "pathological galaxy".
The supermassive black hole at the centre of the Milky Way "eats" asteroids on a regular basis, concluded using the American Chandra X-ray Observatory.
New research shows Earth's clouds are getting little lower, about one percent on average.
According to scientists this indicates that something quite important might be going on.
The results have potential implications for future global climate.
A team of astrophysicists from Germany, France and Italy have discovered in the constellation Leo is an old star.
The star's existence raised at once many questions for scientists.
The object is definitely not as its "contemporaries" that appeared immediately after the Big Bang event.
Have you ever wondered what the Universe will look like for a future alien astronomer?
NGC 5907 is sometimes called the "Splinter" or Knife Edge Galaxy because of its unusual appearance.
It is a spiral galaxy lying in the Dragon constellation,
about 40 million light-years from Earth that could have been formed through a gigantic collision of galaxies, 8 to 9 billion years ago.
The Milky Way is hard to map because we are sitting on the edge of the galaxy looking through it.
However, we know that spiral galaxies like the Milky Way have magnetic fields that follow a particular pattern so we were able
use polarised light to map the magnetic fields...
WASP-12b is the first carbon-rich world ever observed. It is an extremely hot and large gas giant orbiting another star and it has unusual amount of carbon.
Carbon is a common component of planetary systems and a key ingredient of life on Earth.
Does it mean some kind of life might exist on WASP-12b?