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Oct. 31, 2022
The Vela supernova remnant imaged by the VLT Survey Telescope
A spooky spider web, magical dragons or wispy trails of ghosts? What do you see in this image of the Vela supernova remnant? This beautiful tapestry of colours shows the ghostly remains of a gigantic star, and was captured here in incredible detail with the VLT Survey Telescope, hosted at the European Southern Observatory’s (ESO’s) Paranal site in Chile.
The wispy structure of pink and orange clouds is all that remains of a massive star that ended its life in a powerful explosion around 11 000 years ago. When the most massive stars reach the end of their life, they often go out with a bang, in an outburst called a supernova. These explosions cause shock waves that move through the surrounding gas, compressing it and creating intricate thread-like structures. The energy released heats the gaseous tendrils, making them shine brightly, as seen in this image.
Highlights of the Vela supernova remnant
In this 554-million-pixel image, we get an extremely detailed view of the Vela supernova remnant, named after the southern constellation Vela (The Sails). You could fit nine full Moons in this entire image, and the whole cloud is even larger. At only 800 light-years away from Earth, this dramatic supernova remnant is one of the closest known to us.
As it exploded, the outermost layers of the progenitor star were ejected into the surrounding gas, producing the spectacular filaments that we observe here. What remains of the star is an ultra-dense ball in which the protons and electrons are forced together into neutrons — a neutron star. The neutron star in the Vela remnant, placed slightly outside of this image to the upper left, happens to be a pulsar that spins on its own axis at an incredible speed of more than 10 times per second.
VST image processing workflow
Image above:
1. The detector registers the light collected by the telescope. OmegaCAM, the camera attached to the VST, has an array of 32 detectors covering a large field of view.
2. The raw images contain artefacts and instrumental signatures such as dead pixels, shadows, or luminosity variations among detectors. These need to be corrected before the images can be used for scientific purposes.
3. Astronomers correct these effects using calibration data. This process of going from raw to science-ready data is called ‘data reduction’.
4. When an astronomical object is larger than the field of view one needs to stitch together different images, typically called a mosaic. This also allows us to fill in the gaps in between the detectors.
5. The brightness of the background can vary among different parts of the mosaic, especially if they were observed on different nights, because of changes in the phase of the Moon and other effects. For instance, the upper-left corner of image 4 is darker than the rest of the image. By comparing overlapping areas between different images this can be corrected for.
6. The mosaiced image is visually inspected, and any residual artefacts are corrected for. This includes, for example, imperfect seams between adjacent images.
7. Astronomical detectors don’t capture colour images. Instead, several images are taken separately through filters that let through light of different wavelengths. These images are then assigned different colours and combined into a final colour image.
8. The final colour image.
This image is a mosaic of observations taken with the wide-field camera OmegaCAM at the VLT Survey Telescope (VST), hosted at ESO’s Paranal Observatory in Chile. The 268-million-pixel camera can take images through several filters that let through light of different colours. In this particular image of the Vela remnant, four different filters were used, represented here by a combination of magenta, blue, green and red.
The VST is owned by The National Institute for Astrophysics in Italy, INAF, and with its 2.6-metre mirror it is one of the largest telescopes dedicated to surveying the night sky in visible light. This image is an example from such a survey: the VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+). For over seven years, this survey has mapped a considerable portion of our home galaxy, allowing astronomers to better understand how stars form, evolve and eventually die.
Flying through the remnants of a dead star
More information:
The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration in astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates APEX and ALMA on Chajnantor, two facilities that observe the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago, Chile we support our operations in the country and engage with Chilean partners and society.
Links:
Photos of the VLT: http://www.eso.org/public/images/archive/category/paranal/
For journalists: subscribe to receive our releases under embargo in your language: https://www.eso.org/public/outreach/pressmedia/#epodpress_form
For scientists: got a story? Pitch your research: http://www.eso.org/sci/publications/announcements/sciann17463.html
VLT Survey Telescope (VST): https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/
OmegaCAM: https://www.eso.org/public/teles-instr/paranal-observatory/surveytelescopes/vst/camera/
VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+): https://www.vphasplus.org/
ESO’s Paranal Observatory: https://www.eso.org/public/teles-instr/paranal-observatory/
Images Credits: ESO/M Kornmesser/VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit/Video Credits: ESO/VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit/Text Credits: ESO/Juan Carlos Muñoz Mateos.
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