Supernova Leftovers

About 11,000 years ago, a star went supernova. The light from this event first reached Earth around A.D. 1667. There are no records of anyone noticing probably because large amounts of dust between the dying star and Earth obscured our view of the explosion.

The remnants of this supernova was finally noticed in 1947 by radio astronomers. Now known as Cassiopeia A, it is one of the brightest radio sources in the whole sky. More recently, the Wide-field Infrared Survey Explorer (WISE) was used to observe the infrared echoes from the supernova.

When WISE took this image, the blast wave had expanded out to about a distance of 21 light-years, but he flash of light from the explosion, traveling at the speed of light, had covered well over 300 light-years. The orange-colored echoes further out from the central remnant have been reflected from interstellar dust that was heated by the supernova flash centuries after the original explosion.

Image Credit: NASA / JPL / UCLA

Cassiopeia A

The expanding debris cloud known as Cassiopeia A is an example of the final phase of the stellar life cycle. This false-color image was out together using X-ray and optical image data from the Chandra X-ray Observatory and Hubble Space Telescope. IT shows the still hot filaments and knots in the remnant which span about 30 light-years. High-energy X-ray emission from specific elements have been color coded red for silicon, yellow for sulphur, green for calcium, and purple fr iron. The outer blast wave is shown in blue. The bright speck near the center is a neutron star, the incredibly dense, massive collapsed remains of the star’s core.

Image Credits: NASA /STScI

An X-Ray View of a Supernova Remnant

Cassiopeia A (Cas A) is one of the most intensely studied supernova remnants. This false color image from the Chandra X-ray Observatory shows the location of different elements in the remains of the explosion: silicon (red), sulfur (yellow), calcium (green), and iron (purple). Each of those elements produces X-rays within narrow energy ranges, allowing maps of their location to be created. The blue outer ing is supernova’s.

All the elements more complex that hydrogen and helium are forged by fusion in stars, and all the elements further up the periodic table than iron are produced by supernovae. This Chandra data indicate that the Cas A supernova churned out massive amounts of key cosmic ingredients. Cas A produced about 10,000 Earth masses worth of sulfur alone and around 20,000 Earth masses of silicon. The iron in Cas A has the mass of about 70,000 times that of the Earth, but oxygen is the clear winner with one million Earth masses of it being ejected into space from Cas A. That’s about three times the mass of the Sun. However, we can’t “see” any oxygen in this Chandra image. Even though oxygen is the most abundant element in Cas A, its X-ray emissions are spread across a wide range of energies and cannot be isolated in this image.

Image Credit: NASA

Flying Through Cas A

This animation shows what it might be like to fly through of Cas A based on a 3-D model derived from Chandra X-ray and Spitzer IR data. It opens with an artists rendition of the neutron star remains of the original exploded star detected by Chandra. The green region is mostly iron observed in X-rays; the yellow region is mostly argon and silicon seen in X-rays and in visible and infrared light; the red region is cooler debris seen in the infrared and the blue region is the outer blast wave, most prominent in X-rays.

Video Credit: NASA

Sloshing Supernova

This animation was generated the first mapping data of radioactivity in a supernova remnant, the blown-out bits and pieces of a massive star that exploded. The data was take by a NASA satellite called NuSTAR. The results, from a remnant named Cassiopeia A (Cas A), reveal how shock waves probably rip apart massive dying stars.

While small stars like our Sun die less violent deaths, larger stars (at least eight times as massive as the Sun) end up as supernovae. The high temperatures and particles created in explosions fuse lighter elements together to create heavier elements. The explosions of supernovae seeding the universe with many elements, including the gold in jewelry, the calcium in bones, and the iron in blood.

NuSTAR is the first telescope capable of producing maps of radioactive elements in supernova remnants—in this case, titanium-44. The NuSTAR map of Cas A shows the titanium concentrated in clumps at the remnant’s center and suggests a possible solution to the mystery of how the star met its demise. When researchers simulate supernova blasts with computers, as a massive star dies and collapses, the main shock wave often stalls out and the star fails to shatter. The latest findings strongly suggest that Cas A sloshed around, re-energizing the stalled shock wave and allowing the star to finally blow off its outer layers.

Video Credit: NASA

The Remains of a Dead Star

CasA_NuSTARA few weeks ago I posted an X-ray image of Cassiopeia A. recorded by the Chandra X-ray Observatory. Here’s a newer picture taken by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR. In this false color image, blue indicates the highest energy of X-rays, while red and green show the lower end of NuSTAR‘s energy range, which overlaps with NASA’s high-resolution Chandra. X-ray light with energies between 10 and 20 keV (kiloelectron-volt) are blue; X-rays of 8 to 10 keV are green; and X-rays of 4.5 to 5.5 keV are red.

Astronomer’s believe that the first light from the stellar explosion that created Cassiopeia A reached Earth about 300 years ago, after traveling 11,000 years to get here. While the star is dead, its remains are bursting with action. The x-ray represented by the outer blue ring are caused by the shock wave from the supernova blast slamming into surrounding material, accelerating particles up to nearly the speed of light.

Image Credit: NASA