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NGC 6559 (Emission Nebula)


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NGC 6559
Emission Nebula (散光星雲)

Nb EN

別名 (Other names)

LBN 29, ESO 521-N40

星座 (Constellation)
いて座 (Sgr) (Sagittarius)

距離 (Distance)
5,000光年 (5,000 light-years)

NGC 6559 is an emission nebula located 5,000 light years from the Earth in the constellation Sagittarius.

NGC 6559 (Emission Nebula) : Picture

The star formation region NGC 6559
The star formation region NGC 6559
(C) ESO
NGC 6559 is a cloud of gas and dust located at a distance of about 5,000 light-years from Earth, in the constellation of Sagittarius. The glowing region is a relatively small object, just a few light-years across, in contrast to the one hundred light-years and more spanned by its famous neighbour, the Lagoon Nebula (Messier 8). Although it is usually overlooked in favour of its distinguished companion, NGC 6559 has the leading role in this new picture.

The gas in the clouds of NGC 6559, mainly hydrogen, is the raw material for star formation. When a region inside this nebula gathers enough matter, it starts to collapse under its own gravity. The centre of the cloud grows ever denser and hotter, until thermonuclear fusion begins and a star is born. The hydrogen atoms combine to form helium atoms, releasing energy that makes the star shine.

These brilliant hot young stars born out of the cloud energise the hydrogen gas still present around them in the nebula. The gas then re-emits this energy, producing the glowing threadlike red cloud seen near the centre of the image. This object is known as an emission nebula.

But NGC 6559 is not just made out of hydrogen gas. It also contains solid particles of dust, made of heavier elements, such as carbon, iron or silicon. The bluish patch next to the red emission nebula shows the light from the recently formed stars being scattered — reflected in many different directions — by the microscopic particles in the nebula. Known to astronomers as a reflection nebula, this type of object usually appears blue because the scattering is more efficient for these shorter wavelengths of light.

In regions where it is very dense, the dust completely blocks the light behind it, as is the case for the dark isolated patches and sinuous lanes to the bottom left-hand side and right-hand side of the image. To look through the clouds at what lies behind, astronomers would need to observe the nebula using longer wavelengths that would not be absorbed.

The Milky Way fills the background of the image with countless yellowish older stars. Some of them appear fainter and redder because of the dust in NGC 6559.

This eye-catching image of star formation was captured by the Danish Faint Object Spectrograph and Camera (DFOSC) on the 1.54-metre Danish Telescope at La Silla in Chile. This national telescope has been in use at La Silla since 1979 and was recently refurbished to turn it into a remote-controlled state-of-the-art telescope.

The star formation region NGC 6559 in the constellation of Sagittarius
The star formation region NGC 6559 in the constellation of Sagittarius
(C) ESO
This chart shows the location of the glowing clouds of the star formation region NGC 6559 in the constellation of Sagittarius. All the stars visible with the unaided eye on a clear and dark night are shown and NGC 6559 is marked with a red circle. It is a small part of a rich region of star formation and glowing clouds.

Lagoon Nebula, M8, M20, NGC6559 Lagoon Nebula, M8, M20, NGC6559
Lagoon Nebula, M8/Upper Left
M20/Lower Left
NGC 6559/Upper Right
(C) NASA
Lagoon Nebula, M8/Upper Left
M20/Lower Left
NGC 6559/Upper Right
(C) NASA

NGC6559 Lagoon Nebula, M8, M20, NGC6559
NGC 6559
(C) NASA
Lagoon Nebula, M8/Upper Right
M20/Left
NGC 6559/Lower Right
(C) NASA

NGC6559 NGC6559
NGC 6559
(C) NASA
NGC 6559
(C) NASA
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NGC 6559 (Emission Nebula) : Movie

Zooming in on the star formation region NGC 6559
This zoom starts with a broad view of the Milky Way. We head in towards the centre, where stars and the pink regions marking star formation nurseries are concentrated. We see the huge gas cloud of the Lagoon Nebula (Messier 8) but finally settle on the smaller nebula NGC 6559. The colourful closing image comes from the Danish 1.54-metre telescope located at ESO's La Silla Observatory in Chile.

Panning across the star formation region NGC 6559
The Danish 1.54-metre telescope located at ESO's La Silla Observatory in Chile has captured a striking image of NGC 6559, an object that showcases the anarchy that reigns when stars form inside an interstellar cloud. This pan video gives us a close-up view of this region of sky, which includes glowing red clouds of mostly hydrogen gas, blue regions where starlight is being reflected from tiny particles of dust and also dark regions where the dust is thick and opaque.
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