Praise the Lord from the heavens;
give praise in the heights.
Praise him, all you angels;
give praise, all you hosts.
Praise him, sun and moon;
give praise, all shining stars.
Praise him, highest heavens,
you waters above the heavens.
Let them all praise the Lord’s name;
for the Lord commanded and they were created,
Assigned them duties forever,
gave them tasks that will never change.
The word “nova” means “new” in Latin, referring to what appears to be a very bright new star shining in the celestial sphere.
A star is a massive, luminous sphere of plasma held together by its own gravity. Our nearest star is the Sun, the source of most of the energy on Earth.
A supernova is an exploding star that is extremely luminous and causes a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life span. The explosion expels much or all of a star’s material at a velocity of up to 10% of the speed of light, driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.
Using NASA’s Chandra X-ray Observatory, a space telescope launched on the STS-93 Space Shuttle on July 23, 1999, scientists have created a stunning new image of one of the youngest supernova remnants in the Milky Way galaxy — the Kepler Supernova, which is about 13,000 light years from Earth.
This new view of the debris of an exploded star helps astronomers solve a long-standing mystery, with implications for understanding how a star’s life can end catastrophically and for gauging the expansion of the universe.
Over 400 years ago, sky watchers — including the famous astronomer Johannes Kepler — noticed a bright new object in the night sky. Since the telescope had not yet been invented, only the unaided eye could be used to watch as a new star that was initially brighter than Jupiter dimmed over the following weeks.
The explosion of the star that created the Kepler remnant blasted the stellar remains into space, heating the gases to millions of degrees and generating highly energized particles. Copious X-ray light, like that shining from many supernova remnants, was produced.
Astronomers have studied Kepler intensively over the past three decades with radio, optical and X-ray telescopes, but its origin has remained a puzzle. By comparing the relative amounts of oxygen and iron atoms in the Kepler supernova, a team of astronomers led by Stephen Reynolds of North Carolina State University in Raleigh, N.C., were able to determine that Kepler resulted from a Type Ia supernova. Such a supernova is produced when a white dwarf star pulls material from an orbiting companion until the white dwarf becomes unstable and is destroyed by a thermonuclear explosion.
Type Ia stars are the source of most of the iron in the universe.
In the Chandra Kepler image above, red represents low-energy X-rays and shows material around the star — dominated by oxygen — that has been heated up by a blast wave from the star’s explosion. The yellow color shows slightly higher energy X-rays, mostly iron formed in the supernova, while green (medium-energy X-rays) shows other elements from the exploded star. The blue color represents the highest energy X-rays and shows a shock front generated by the explosion.