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News Release 430 of 938

June 3, 2004 09:00 AM (EDT)

News Release Number: STScI-2004-17

New Hubble Image Reveals Details in the Heart of the Trifid Nebula

A Hubble Heritage Release

June 3, 2004: Three huge intersecting dark lanes of interstellar dust make the Trifid Nebula one of the most recognizable and striking star birth regions in the night sky. The dust, silhouetted against glowing gas and illuminated by starlight, cradles the bright stars at the heart of the Trifid Nebula. This nebula, also known as Messier 20 and NGC 6514, lies within our own Milky Way Galaxy about 9,000 light-years (2,700 parsecs) from Earth, in the constellation Sagittarius. This new image from the Hubble Space Telescope offers a close-up view of the center of the Trifid Nebula, near the intersection of the dust bands, where a group of recently formed, massive, bright stars is easily visible.

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Q & A: Understanding the Discovery

  1. 1. How did the Trifid Nebula get its name?


  2. The Trifid Nebula, cataloged by astronomers as Messier 20 or NGC 6514, is a well-known region of star formation lying within our own Milky Way Galaxy. It is called the Trifid because the nebula is overlain by three bands of obscuring interstellar dust, giving it a trisected appearance as seen in small telescopes.

  3. 2. Where is the Nebula located?


  4. The Trifid lies about 9,000 light-years (2,700 parsecs) from Earth, in the direction of the constellation Sagittarius.

  5. 3. What is happening in the center of this nebula?


  6. This new image from the Hubble Space Telescope offers a close-up view of the center of the Trifid Nebula, near the intersection of the dust bands, where a group of recently formed, massive, bright stars is easily visible. These stars, which astronomers classify as belonging to the hottest and bluest types of stars known, type "O," are releasing a flood of ultraviolet radiation that dramatically influences the structure and evolution of the surrounding nebula. The stars illuminate a dense pillar of gas and dust to the right of the image, producing a bright rim on the side facing the stars. At the upper left tip of this pillar, there is a complex filamentary structure also on the side closest to the center of the nebula. The structure has a bluish color because it is made up of glowing oxygen gas that is evaporating into space.

  7. 4. Is this nebula still forming new stars?


  8. Star formation is no longer occurring in the immediate vicinity of the conspicuous group of bright O-type stars, because their intense radiation has blown away the gas and dust from which stars are made. However, not far away there are signs of interstellar material collapsing under its own gravity, leading to ongoing star formation. One such example is a very young star that is still surrounded by a ring of gas and dust left over from the star's formation. These circumstellar rings, called protoplanetary disks, or "proplyds" for short, are believed to be the locations where planetary systems are formed. A proplyd in the Trifid Nebula is visible near the lower right of the main Hubble image. An image enlargement of the proplyd is shown in the lower left box, where its elongated shape can be seen.

  9. 5. Has the jet that is shown in the image shown any movement over the last few years?


  10. In the box at upper right, a jet of material is seen being ejected from a very young, low-mass star. The jet, extending to the lower right of the box, protrudes from the head of a dense pillar and extends three-quarters of a light-year out into the surrounding thin gas. The jet's source is a very young stellar object that lies buried within the pillar. Previous Hubble images of the Trifid Nebula, taken in 1997, show very small, but noticeable changes in the knotty material being ejected from this jet.

 
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Image Credit: NASA, ESA, and The Hubble Heritage Team (AURA/STScI)

Acknowledgment: F. Yusef-Zadeh (Northwestern Univ.)