A Spooky Ghost of a Giant Star: What Remains After the Explosive Death of a Massive Star

What do you see in this intricate image of the Vela supernova remnant?

A spooky spider web, magical dragons, or wispy trails of ghosts?

This beautiful tapestry of colors shows the ghostly remains of a gigantic star after a cosmic catastrophe. It was captured here in remarkable detail with the VLT Survey Telescope, hosted at the European Southern Observatory’s (ESO’s) Paranal site in Chile.

All that remains of a massive star that ended its life in a powerful explosion around 11,000 years ago is this wispy structure of pink and orange clouds. When massive stars reach the end of their life, they often go out with a bang, in an outburst called a supernova. These massive cosmic 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.

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. This dramatic supernova remnant is one of the closest known to us, at a distance of only 800 light-years away from Earth.

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 astonishing speed of more than 10 times per second.

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 artifacts 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 artifacts are corrected for. This includes, for example, imperfect seams between adjacent images.
7. Astronomical detectors don’t capture color images. Instead, several images are taken separately through filters that let through light of different wavelengths. These images are then assigned different colors and combined into a final color image.
8. The final color 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 colors. In this particular image of the Vela remnant, four different filters were used, represented here by a combination of magenta, blue, green, and red.

In this video we get to fly around in the highly detailed image of the beautiful and dramatic Vela supernova remnant, captured with OmegaCAM at the VST telescope, hosted at ESO’s Paranal Observatory in Chile. The image consists of 554 million pixels, revealing myriad stars and thin gaseous filaments, the latter created by shock waves from the explosion of a massive star 11,000 years ago. Credit: ESO/VPHAS+ team, Acknowledgment: Cambridge Astronomical Survey Unit

The VST is owned by The National Institute for Astrophysics in Italy, INAF, and with its 2.6-meter 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 Ha 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.

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