Image Credit: ESO/VVV consortium/D. Minniti
The universe is a painstakingly large place, even mapping a small sliver of sky takes a lot of manpower and telescope time. For the southern sky, no recent survey has been more successful than VISTA, which is operated by the ESO's Paranal Observatory in Chile; it specifically focuses on light at infrared portions of the electromagnetic spectrum. These wavelengths pull back the curtain, so to speak, allowing us to view objects that are all but
hidden from the human eye.
in a new image, taken by the VVV survey — an acronym for 'VISTA Variables in the Via Lactea' — we see a well-known star forming region, called the
Trifid nebula (otherwise known as Messier 20), in a new light. The region in question can be found about 5,200 light-years from Earth in the Sagittarius constellation.
The VVV Survey takes particular interest in variable objects, or those that vary in luminosity over time. Trifid, which lies just 27,000 light-years away from the center of the Milky Way, was zeroed in on by VVV in hopes of identifying
Cepheid variable stars. The ESO explains further,
[box style="0"]The familiar pictures of the Trifid show it in visible light, where it glows brightly in both the pink emission from ionised hydrogen and the blue haze of scattered light from hot young stars. Huge clouds of light-absorbing dust are also prominent. But the view in the VISTA infrared picture is very different. The nebula is just a ghost of its usual visible-light self. The dust clouds are far less prominent and the bright glow from the hydrogen clouds is barely visible at all. The three-part structure is almost invisible.
In the new image, as if to compensate for the fading of the nebula, a spectacular new panorama comes into view. The thick dust clouds in the disc of our galaxy that absorb visible light allow through most of the infrared light that VISTA can see. Rather than the view being blocked, VISTA can see far beyond the Trifid and detect objects on the other side of the galaxy that have never been seen before.
By chance this picture shows a perfect example of the surprises that can be revealed when imaging in the infrared. Apparently close to the Trifid in the sky, but in reality about seven times more distant, a newly discovered pair of variable stars has been found in the VISTA data. These are Cepheid variables, a type of bright star that is unstable and slowly brightens and then fades with time. This pair of stars, which the astronomers think are the brightest members of a cluster of stars, are the only Cepheid variables detected so far that are close to the central plane, but on the far side of the galaxy. They brighten and fade over a period of eleven days.
[See the full press release
here] [/box]
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