kepler's supernova

833 years ago, on August 4, 1181, astronomers in what is now China and Japan noted a supernova, one of several celestial phenomena to be noted by the East but ignored by the West.  Now known as SN 1181 or 3C58, the remains of this massive explosion can still be seen. While plenty of modern scientific words can be dated accurately, the older a word is (in general) the harder it is to pin down a date.  The word supernova however, defies this logic entering the European awarness in the 16th century.  Late October 1604 (and some sources give the date 6 November 1604) a new and bright object appeared in the sky.  German astronomer and mathematician Johannes Kepler (born 27 December 1571-15 November 1630) noticed the ‘new’ object and unsure what exactly it was, simply named it stella nova, from the Latin words for new star.  It wasn’t until the 1930s that astronomers Walter Baade and Fritz Zwicky started using the term super-nova and by 1938 the hyphen was dropped and the word became supernova.  The first reliably recorded supernova was noted by Pliny in AD 185.  Notable supernovae (note the plural maintains the Latin form and does not take the -s that English mostly uses) occurred in 1054, noted mainly by Chinese and Arabic astronomers, and the supernova of 1572 noted extensively by Tycho Brahe.  The definition of supernova: the explosion of a star, possibly caused by gravitational collapse, during which the star’s luminosity increases by as much as 20 magnitudes and most of the star’s mass is blown away at very high velocity.

This image of Supernova 1181 comes from NASA’s Chandra program with this caption:  3C58 is the remnant of a supernova observed in the year 1181 AD by Chinese and Japanese astronomers. This new Chandra image shows the center of 3C58, which contains a rapidly spinning neutron star surrounded by a thick ring, or torus, of X-ray emission. The pulsar also has produced jets of X-rays blasting away from it to both the left and right, and extending trillions of miles. These jets are responsible for creating the elaborate web of loops and swirls revealed in the X-ray data. These features, similar to those found in the Crab, are evidence that 3C58 and others like it are capable of generating both swarms of high-energy particles and powerful magnetic fields. In this image, low, medium, and high-energy X-rays detected by Chandra are red, green, and blue respectively.

 

Supernova 1604, also known as Kepler’s Supernova, Kepler’s Nova or Kepler’s Star, was a supernova that occurred in the Milky Way, in the constellation Ophiuchus. As of Feb 2012, it is the last supernova to have been unquestionably observed in our own galaxy, occurring no farther than 6 kiloparsecs or about 20,000 light-years from Earth. Visible to the naked eye, it was brighter at its peak than any other star in the night sky, and all the planets (other than Venus), with apparent magnitude −2.5. It was visible during the day for over three weeks.

Kepler clue to supernova puzzle

Two white dwarfs favoured as precursors of type Ia supernovae.

They are cosmic detonations that briefly outshine the light of entire galaxies. And they were a crucial tool in the discovery of dark energy, the force that is accelerating the expansion of the Universe. Yet the process that gives rise to type Ia supernovae has remained mysterious.

Now, light from two of these stellar explosions has been captured in finer temporal detail than ever before, and the data are adding weight to an emerging view: that the explosions result from the merger of two white dwarfs, the burnt-out, Earth-sized remnants of Sun-like stars. The finding erodes a long-standing view that type Ia supernovae arise from a single white dwarf accruing material from an ordinary companion star, either a Sun-like star or an elderly, bloated red giant.

Continue Reading