Anne’s Image of the Day: Reflection Nebula NGC 1999

March 6, 2014

NGC 1999, a reflection nebula in Orion

Image Credit & Copyright: Robert Gendler

NGC 1999 is a bluish reflection nebula of roughly 0.6 light-year across, located some 1,500 light-years away from Earth in the constellation of Orion (the Hunter). In the middle is a vast, 0.2-light-year-wide hole of empty space represented by a black patch of sky, called “Parsamian 34”.

NGC 1999 is located in a fertile region of low mass star formation. Infrared instruments have detected several young clusters of stars hidden from optical view behind the extensive, dense, reddish dust clouds surrounding NGC 1999.

Just to the left of the black patch is the young, bright star that is illuminating the dust filled, bright bluish reflection nebula. (The spectrum of the star and the nebula are identical which tells us that what we see is truly reflected starlight.) This star is cataloged as V380 Orionis, and its white color is due to its high surface temperature of about 10,000 degrees Celsius (nearly twice that of our own Sun). Its mass is estimated to be 3.5 times that of the Sun. The star is so young that it is still surrounded by a cloud of material left over from its formation, here seen as the bluish reflection nebula.

It was previously believed that the black patch (Parsamian 34) was a dense cloud of dust and gas which blocked light that would normally pass through, called a dark nebula. However, analysis of Parsamian 34 by the infrared telescope Herschel (October 9, 2009), which has the capability of penetrating such dense cloud material, resulted in continued black space.

Anyway, with support from ground-based observations done in November and December 2009, it was determined that the patch looks black not because it is an extremely dense pocket of gas, but because it is truly empty. The exact cause of this phenomenon is still being investigated, although astronomers think that the star is launching a bipolar jet at hundreds of kilometers per second that is punching a gigantic hole in the surrounding cloud. Essentially these bolts of gas are probably being shot forward and are sweeping away all the gas and dust.

This composite wide-field image is created by using three data sources: the 8.2 Meter Subaru Telescope (NAOJ), the Hubble Space Telescope, and the color data by the Digitized Sky Survey from Robert Gendler. Image Assembly and Processing is also by Robert Gendler. The image is based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive.