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Extremely intense radiation from newly born, ultra-bright stars has blown a glowing spherical bubble in the nebula N83B, also known as NGC
1748. A new NASA Hubble Space Telescope image
has helped to decipher the complex interplay of gas and radiation of a star-forming region in a nearby galaxy. The image graphically illustrates just how these massive stars sculpt their environment by generating powerful winds that alter the shape of the parent gaseous nebula. These processes are also seen in our Milky Way in regions like the Orion Nebula.
The Hubble telescope is famous for its contribution to our knowledge about star
formation in very distant galaxies. Although
most of the stars in the Universe were born several billions of years ago, when the
Universe was young, star formation still
continues today. This new Hubble image shows a very compact star-forming region in a small
part of one of our neighboring galaxies – the Large Magellanic Cloud. This galaxy lies only 165,000 light-years from our Milky Way and
can easily be seen with the naked eye from the Southern Hemisphere.
Young, massive, ultra-bright stars are seen here just as they are born and emerge from the shelter of their pre-natal molecular cloud. Catching
these hefty stars at their birthplace is not as easy as it may seem. Their high mass means that the young stars evolve very rapidly and are hard to find at this critical stage. Furthermore,
they spend a good fraction of their youth hidden from view, shrouded by large quantities of dust
in a molecular cloud. The only chance is to observe them just as they start to emerge from their cocoon – and then only with very high-resolution telescopes.
Astronomers from France, the U.S., and Germany have used Hubble to study the fascinating interplay between gas, dust, and radiation from
the newly born stars in this nebula. Its peculiar and turbulent structure has been revealed for the first time. This high-resolution study has also uncovered several individual stars that are responsible for lighting up this cloud of gas.
The apparently innocuous-looking star at the very center of the nebula, just below the brightest region, is actually about 30 times more massive and almost 200,000 times brighter than our Sun. The intense light and powerful stellar “winds” from this ultra-bright star have cleared away the surrounding gas to form a large cavity. The
bubble is approximately 25 light-years in
diameter – about the same size as the famous star-forming Orion Nebula. The Orion Nebula is sculpted by intense radiation from newly born stars in the same way as N83B. Astronomers estimate that the spherical void in N83B must
have been carved out of the nebula very recently
– in astronomical terms – maybe as little as 30,000 years ago.
The hottest star in N83B is 45 times more massive than the Sun and is embedded in the brightest region in the nebula. This bright region,
situated just above the center, is only about 2 light-years across. The region’s small size and its intense glow are telltale signs of a very
young, massive star. This star is the youngest newcomer to this part of the Large Magellanic Cloud. The Hubble image shows a bright arc
structure just below the luminous star. This impressive ridge may have been created in the glowing gas by the hot star’s powerful wind.
Measurements of the age of this star and neighboring stars in the nebula show that they
are younger than the nebula’s central star.
Their formation may have been “triggered” by the violent wind from the central star. This “chain-reaction” of stellar births seems to be
common in the Universe. About 20 young and luminous stars have been identified in the
region, but it may well be that many more
massive stars remain undetected in other areas
of the Large Magellanic Cloud, hidden by dust
in small clusters like N83B.
To the right of the glowing N83B is a much larger diffuse nebula, known as DEM22d, which is partly obscured by an extended lane of dust and gas.
This image is composed of three narrow-band-
filter images obtained with Hubble’s Wide Field Planetary Camera 2 in May 2000. The colors are
red (ionized hydrogen, H-alpha), green (ionized oxygen), and blue (ionized hydrogen, H-beta).
The blue corresponds to the warmest regions, the red to the coldest. The full image is 66 x 133 arc-seconds, which corresponds to 55 x 108 light-years at the distance of the Large
Magellanic Cloud.
Credit: NASA, ESA, Mohammad Heydari-Malayeri (Observatoire de Paris, France)
NOTES FOR EDITORS: The Hubble Space Telescope is a project of international co-operation between NASA and ESA.
This release is issued jointly by NASA and ESA.
The scientists involved in these observations are M. Heydari-Malayeri (Observatoire de Paris, France), V. Charmandaris (Cornell University,
U.S.), L. Deharveng (Observatoire de Marseille, France), M.R. Rosa (Space Telescope-European Coordinating Facility, Germany), D. Schaerer
(Observatoire Midi-Pyrenees, France) and H. Zinnecker (Astrophysikalisches Institut Potsdam, Germany).
The results will be published in the Astronomy
and Astrophysics journal.
For additional information, please contact Lars Lindberg Christensen, Hubble European Space
Agency Information Centre, Garching, Germany,
+49-(0)89-3200-6306 (phone), +49-(0)173-38-72-621 (24 hr. cell phone), lars@eso.org (e-mail) or
Mohammad Heydari-Malayeri, Observatoire de Paris, France, +33-1-40-51-20-76 (phone), heydari@obspm.fr (e-mail) or
Ray Villard, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, 410-338-4514 (phone), villard@stsci.edu (e-mail).
Electronic images are available on the Web at:
http://oposite.stsci.edu/pubinfo/pr/2001/11 and via links in:
http://hubble.stsci.edu/go/news
http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html and
http://hubble.esa.int
