NGC 1999

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NGC 1999 is one of the most beautiful (and interesting) nebulae in the night sky. It is very faint and, as other nebulae, a nice mixture of emission, reflection and dark nebulae. Being located in the Orion area, it is a place where star birth takes place more frequently than in other regions.

Usually, the images of NGC 1999 (the light blue patch above the center of this image) had been accompanied by the interpretation that the dark patch at its center (resembling a keyhole, much more than the one at the Keyhole nebula) was a dark nebula (one composed by colder gas and dust). Please see below the famous image taken by the Hubble Space Telescope:

Image copyright and credit NASA-ESA-Hubble Space Telescope

Anyhow, the Herschel Observatory (a space telescope sensitive to infra-red wavelengths), determined that the hole was not a classical dark nebula, not even an “extremely dense” one, as it had also been hypothesized, but simply it is a void region. Most probably, one young, triple close by star (Orion V380) has wiped off all gas from that region (see http://www.nasa.gov/mission_pages/herschel/herschel20100511b.html).

Being this region so rich in newly formed stars, it is no surprise that several Herbig-Haro objects can be found in this image. Herbig-Haro (HH) objects are always associated to recently born stars. Jets of material and radiation being emitted by these stars, collide with the surrounding gas-dust environment, creating a shock bow that can emit visible radiation. Herbig and Haro focused on objects visible in photographs and recorded their spectra, showing an outstanding emission in the classical emission lines (Hydrogen, Oxygen and Sulphur). As many as 13 such objects can be seen in this image (see below an annotated image):

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