Setting the Dark on Fire
Reflection Nebula NGC 1999 in Orion
The wide-field area around NGC 1999 in Orion
Videos
Setting the Dark on Fire (zoom)
Setting the Dark on Fire (pan)
A new image from the Atacama Pathfinder
Experiment (APEX) telescope in Chile shows a beautiful view of clouds of
cosmic dust in the region of Orion. While these dense interstellar
clouds seem dark and obscured in visible-light observations, APEX’s
LABOCA camera can detect the heat glow of the dust and reveal the hiding
places where new stars are being formed. But one of these dark clouds
is not what it seems.
In space, dense clouds of cosmic gas and dust are the birthplaces of
new stars. In visible light, this dust is dark and obscuring, hiding the
stars behind it. So much so that, when astronomer William Herschel
observed one such cloud in the constellation of Scorpius in 1774, he
thought it was a region empty of stars and is said to have exclaimed, "Truly there is a hole in the sky here!" [1]
In order to better understand star formation, astronomers need
telescopes that can observe at longer wavelengths, such as the
submillimetre range, in which the dark dust grains shine rather than
absorb light. APEX, on the Chajnantor Plateau in the Chilean Andes, is
the largest single-dish submillimetre-wavelength telescope operating in
the southern hemisphere, and is ideal for astronomers studying the birth
of stars in this way.
Located in the constellation of Orion (The Hunter), 1500 light-years
away from Earth, the Orion Molecular Cloud Complex is the closest region
of massive star formation to Earth, and contains a treasury of bright
nebulae, dark clouds and young stars. The new image shows just part of
this vast complex in visible light, with the APEX observations overlaid
in brilliant orange tones that seem to set the dark clouds on fire.
Often, the glowing knots from APEX correspond to darker patches in
visible light — the tell-tale sign of a dense cloud of dust that absorbs
visible light, but glows at submillimetre wavelengths, and possibly a
site of star formation.
The bright patch below of the centre of the image is the nebula NGC
1999. This region — when seen in visible light — is what astronomers
call a reflection nebula, where the pale blue glow of background
starlight is reflected from clouds of dust. The nebula is mainly
illuminated by the energetic radiation from the young star V380 Orionis
[2] lurking at its heart. In the centre of the nebula is a dark patch, which can be seen even more clearly in a well-known
image from the NASA/ESA Hubble Space Telescope.
Normally, a dark patch such as this would indicate a dense cloud of
cosmic dust, obscuring the stars and nebula behind it. However, in this
image we can see that the patch remains strikingly dark, even when the
APEX observations are included. Thanks to these APEX observations,
combined with infrared observations from other telescopes, astronomers
believe that the patch is in fact a hole or cavity in the nebula,
excavated by material flowing out of the star V380 Orionis. For once, it
truly is a hole in the sky!
The region in this image is located about two degrees south of the
large and well-known Orion Nebula (Messier 42), which can be seen at the
top edge of the wider view in visible light from the Digitized Sky
Survey.
The APEX observations used in this image were led by Thomas Stanke
(ESO), Tom Megeath (University of Toledo, USA), and Amy Stutz (Max
Planck Institute for Astronomy, Heidelberg, Germany). APEX is a
collaboration between the Max Planck Institute for Radio Astronomy
(MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX
at Chajnantor is entrusted to ESO.
Notes
[1] In German, "Hier ist wahrhaftig ein Loch im Himmel!"
[2] V380 Orionis has a high surface temperature of
about 10 000 Kelvin (about the same in degrees Celsius), nearly twice
that of our own Sun. Its mass is estimated to be 3.5 times that of the
Sun.
More information
The year 2012 marks the 50th anniversary of
the founding of the European Southern Observatory (ESO). ESO is the
foremost intergovernmental astronomy organisation in Europe and the
world’s most productive ground-based astronomical observatory by far. It
is supported by 15 countries: Austria, Belgium, Brazil, the Czech
Republic, Denmark, France, Finland, Germany, Italy, the Netherlands,
Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries
out an ambitious programme focused on the design, construction and
operation of powerful ground-based observing facilities enabling
astronomers to make important scientific discoveries. ESO also plays a
leading role in promoting and organising cooperation in astronomical
research. ESO operates three unique world-class observing sites in
Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the
Very Large Telescope, the world’s most advanced visible-light
astronomical observatory and two survey telescopes. VISTA works in the
infrared and is the world’s largest survey telescope and the VLT Survey
Telescope is the largest telescope designed to exclusively survey the
skies in visible light. ESO is the European partner of a revolutionary
astronomical telescope ALMA, the largest astronomical project in
existence. ESO is currently planning the 39-metre European Extremely
Large optical/near-infrared Telescope, the E-ELT, which will become “the
world’s biggest eye on the sky”.
Links
- The research into the dark patch in NGC 1999 discussed above is described in a paper by T. Stanke et al., A&A 518, L94 (2010), also available as a preprint.
Contacts
Thomas Stanke
ESO
Garching, Germany
Tel: +49 89 3200 6116
Email: tstanke@eso.org
Douglas Pierce-Price
ESO ALMA/APEX Public Information Officer
Garching, Germany
Tel: +49 89 3200 6759
Email: dpiercep@eso.org
