ESO's VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.
The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula [1]. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image.
The nebula itself is a complex object composed of dust, ionised material as well as molecular gas, arrayed in a beautiful and intricate flower-like pattern and glowing in the fierce glare of ultraviolet light from the central hot star.
The main ring of the Helix is about two light-years across, roughly half the distance between the Sun and the nearest star. However, material from the nebula spreads out from the star to at least four light-years. This is particularly clear in this infrared view since red molecular gas can be seen across much of the image.
While hard to see visually, the glow from the thinly spread gas is easily captured by VISTA's special detectors, which are very sensitive to infrared light. The 4.1-metre telescope is also able to detect an impressive array of background stars and galaxies.
The powerful vision of ESO's VISTA telescope also reveals fine structure in the nebula's rings. The infrared light picks out how the cooler, molecular gas is organised. The material clumps into filaments that radiate out from the centre and the whole view resembles a celestial firework display.
This comparison shows a new view of the Helix Nebula acquired with the VISTA telescope in infrared light (left) and the more familiar view in visible light from the MPG/ESO 2.2-metre telescope (right). The infrared vision of VISTA reveals strands of cold nebular gas that are mostly obscured in visible light images of the Helix. An interactive comparison image can be found here
Credit: ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit
Even though they look tiny, these strands of molecular hydrogen, known as cometary knots, are about the size of our Solar System. The molecules in them are able to survive the high-energy radiation that emanates from the dying star precisely because they clump into these knots, which in turn are shielded by dust and molecular gas. It is currently unclear how the cometary knots may have originated.
Notes:
[1] Planetary nebulae have nothing to do with planets. This confusing name arose because many of them show small bright discs when observed visually and resemble the outer planets in the Solar System, such as Uranus and Neptune. The Helix Nebula, which also bears the catalogue number NGC 7293, is unusual as it appears very large, but also very faint, when viewed through a small telescope.
The Helix Nebula is one of the closest and most remarkable examples of a planetary nebula [1]. It lies in the constellation of Aquarius (The Water Bearer), about 700 light-years away from Earth. This strange object formed when a star like the Sun was in the final stages of its life. Unable to hold onto its outer layers, the star slowly shed shells of gas that became the nebula. It is evolving to become a white dwarf star and appears as the tiny blue dot seen at the centre of the image.
ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) has captured this unusual view of the Helix Nebula (NGC 7293), a planetary nebula located 700 light-years away. The coloured picture was created from images taken through Y, J and K infrared filters. While bringing to light a rich background of stars and galaxies, the telescope's infrared vision also reveals strands of cold nebular gas that are mostly obscured in visible images of the Helix.
Credit: ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit
The nebula itself is a complex object composed of dust, ionised material as well as molecular gas, arrayed in a beautiful and intricate flower-like pattern and glowing in the fierce glare of ultraviolet light from the central hot star.
The main ring of the Helix is about two light-years across, roughly half the distance between the Sun and the nearest star. However, material from the nebula spreads out from the star to at least four light-years. This is particularly clear in this infrared view since red molecular gas can be seen across much of the image.
This chart shows the location of the Helix Nebula within the constellation of Aquarius. This map shows most of the stars visible to the unaided eye under good conditions and the nebula itself is marked with a red circle. This nebula is large but very faint and can be seen with binoculars or a small telescope only when the sky is exceptionally dark and clear.
Credit: ESO, IAU and Sky & Telescope
While hard to see visually, the glow from the thinly spread gas is easily captured by VISTA's special detectors, which are very sensitive to infrared light. The 4.1-metre telescope is also able to detect an impressive array of background stars and galaxies.
This visible-light wide-field image of the region around the Helix Nebula was created from photographs taken through red and blue filters and forming part of the Digitized Sky Survey 2. The nebula appears prominently at the centre of the image and many faint galaxies are also visible on careful inspection. The field of view is approximatelly 2.9 x 2.9 degrees.
Credit: ESO/Digitized Sky Survey 2. Acknowledgment: Davide De Martin
The powerful vision of ESO's VISTA telescope also reveals fine structure in the nebula's rings. The infrared light picks out how the cooler, molecular gas is organised. The material clumps into filaments that radiate out from the centre and the whole view resembles a celestial firework display.
This comparison shows a new view of the Helix Nebula acquired with the VISTA telescope in infrared light (left) and the more familiar view in visible light from the MPG/ESO 2.2-metre telescope (right). The infrared vision of VISTA reveals strands of cold nebular gas that are mostly obscured in visible light images of the Helix. An interactive comparison image can be found here
Credit: ESO/VISTA/J. Emerson. Acknowledgment: Cambridge Astronomical Survey Unit
Even though they look tiny, these strands of molecular hydrogen, known as cometary knots, are about the size of our Solar System. The molecules in them are able to survive the high-energy radiation that emanates from the dying star precisely because they clump into these knots, which in turn are shielded by dust and molecular gas. It is currently unclear how the cometary knots may have originated.
Notes:
[1] Planetary nebulae have nothing to do with planets. This confusing name arose because many of them show small bright discs when observed visually and resemble the outer planets in the Solar System, such as Uranus and Neptune. The Helix Nebula, which also bears the catalogue number NGC 7293, is unusual as it appears very large, but also very faint, when viewed through a small telescope.
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