Aug

Twenty years later, “First Light” continues to glow

Monday, August 26, marks 20 years to the day since we received the “First Light” image from NASA’s Chandra X-ray Observatory, of an exploded star 11,000 light-years away called Cassiopeia A. To celebrate, SAO has created a short video that shows how Cas A has evolved over the years, as captured by Chandra.

On July 23, 1999, the Space Shuttle Columbia launched into space carrying the heaviest payload ever flown. In its cargo bay NASA’s Chandra X-ray Observatory, a first-of-its-kind telescope that would open a new window into exploring the Universe.

Artists rendering of Chandra spacecraft. Credit: NASA/CXC/SAO & J. Vaughan

Unlike the Hubble Space Telescope, its older cousin, Chandra detects X-rays from space instead of the kind of light that humans can see. Only a handful of decades before, scientists didn’t know objects in space gave off X-rays. Because the Earth’s atmosphere absorbs this high-energy light, people had to wait until the dawn of the Space Age to realize that space is aglow in light that invisible to our eyes. Once known, a different kind of space race emerged.

Chandra has captured many spectacular images of cosmic phenomena over its two decades of operations, but perhaps its most iconic is the supernova remnant Cassiopeia A.

Located about 11,000 light-years from Earth, Cas A (as it’s nicknamed) is the glowing debris field left behind after a massive star exploded. When the star ran out of fuel, it collapsed onto itself and blew up as a supernova, possibly briefly becoming one of the brightest objects in the sky. (Although astronomers think that this happened around the year 1680, there are no verifiable historical records to confirm this.)

Cassiopeia A in X-ray and optical light. This latest study of Cassiopeia A (Cas A) adds to a long collection of Chandra discoveries over the course of the telescope’s 20 years. In addition to finding the central neutron star, Chandra data have revealed the distribution of elements essential for life ejected by the explosion, have constructed a remarkable three dimensional model of the supernova remnant, and much more. This still image combines data from Chandra color coded by element with data from the Hubble Space Telescope.
Credit: X-ray: NASA/CXC/SAO; Optical:NASA/STScI

The shock waves generated by this blast supercharged the stellar wreckage and its environment, making the debris glow brightly in many types of light, particularly X-rays. Shortly after Chandra was launched aboard the Space Shuttle Columbia on July 23, 1999, astronomers directed the observatory to point toward Cas A. It was featured in Chandra’s official “First Light” image, released Aug. 26, 1999, and marked a seminal moment not just for the observatory, but for the field of X-ray astronomy. Near the center of the intricate pattern of the expanding debris from the shattered star, the image revealed, for the first time, a dense object called a neutron star that the supernova left behind

Since then, Chandra has repeatedly returned to Cas A to learn more about this important object. A new video shows the evolution of Cas A over time, enabling viewers to watch as incredibly hot gas — about 20 million degrees Fahrenheit — in the remnant expands outward. These X-ray data have been combined with data from another of NASA’s “Great Observatories,” the Hubble Space Telescope, showing delicate filamentary structures of cooler gases with temperatures of about 20,000 degrees Fahrenheit. Hubble data from a single time period are shown to emphasize the changes in the Chandra data.

The video shows Chandra observations of Cas A from 2000 to 2013. In that time, a child could enter kindergarten and graduate from high school. This gives astronomers a rare chance to watch as a cosmic object changes on human timescales, giving them new insight into the physics involved. For example, particles in the blue outer shock wave carry more energy than those produced by the most powerful particle accelerators on Earth. As this blast wave hits material in its path it slows down, sending a shock wave backwards at speeds of millions of miles per hour.

Chandra will continue to observe Cassiopeia A in the future, adding to its remarkable legacy of discovery for this supernova remnant.

NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science and flight operations from Cambridge, Massachusetts.

First Light

The Chandra X-ray Observatory is the culmination of decades of collaboration between scientists and engineers, private and public institutions, the United States and those around the world. Two decades after its launch, Chandra remains the most powerful X-ray telescope and continues to reveal secrets about black holes, exploded stars, and the nature of the Universe itself. See for yourself what wonders Chandra has to behold in this film from Steer Films & NASA/CXC/SAO.