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Joseph loves astroomy and they have been talking about Kepler's Supernova, the most recent supernova to be observed within the Milky Way, on a day like today in 1604. SN 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Type Ia supernova that occurred in the Milky Way, in the constellation Ophiuchus.
Appearing in 1604, it is the most recent supernova in the Milky Way galaxy to have been unquestionably observed by the naked eye, occurring no farther than 6 kiloparsecs (20,000 light-years) from Earth. Before the adoption of the current naming system for supernovae, it was named for Johannes Kepler, the German astronomer who described it in De Stella Nova.
Visible to the naked eye, Kepler's Star was brighter at its peak than any other star in the night sky, with an apparent magnitude of -2.5. It was visible during the day for over three weeks. Records of its sighting exist in European, Chinese, Korean, and Arabic sources.
It was the second supernova to be observed in a generation (after SN 1572 seen by Tycho Brahe in Cassiopeia). No further supernovae have since been observed with certainty in the Milky Way, though many others outside the galaxy have been seen since S Andromedae in 1885. SN 1987A in the Large Magellanic Cloud was visible to the naked eye.
Evidence exists for two Milky Way supernovae whose signals would have reached Earth c. 1680 and 1870 -Cassiopeia A, and G1.9+0.3 respectively. There is no historical record of either having been detected in those years probably as absorption by interstellar dust made them fainter.
The remnant of Kepler's supernova is considered to be one of the prototypical objects of its kind and is still an object of much study in astronomy.
The supernova remnant of SN 1604, Kepler's Star, was discovered in 1941 at the Mount Wilson Observatory as a dim nebula with a brightness of 19 mag. Only filaments can be seen in visible light, but it is a strong radio and X-ray source. Its diameter is 4 arc min. Distance estimates place it between 3 and more than 7 kiloparsecs (10,000 to 23,000 lightyears), with the current consensus being a distance of 5±1 kpc, as of 2021.
The available evidence supports a type Ia supernova as the source of this remnant, which is the result of a carbon-oxygen white dwarf interacting with a companion star. The integrated X-ray spectrum resembles that of Tycho's supernova remnant, a type Ia supernova. The abundance of oxygen relative to iron in the remnant of SN 1604 is roughly solar, whereas a core-collapse scenario should produce a much higher abundance of oxygen. No surviving central source has been identified, which is consistent with a type Ia event. Finally, the historical records for the brightness of this event are consistent with type Ia supernovae.
There is evidence for interaction of the supernova ejecta with circumstellar matter from the progenitor star, which is unexpected for type Ia but has been observed in some cases. A bow shock located to the north of this system is believed to have been created by mass loss prior to the explosion. Observations of the remnant are consistent with the interaction of a supernova with a bipolar planetary nebula that belonged to one or both of the progenitor stars.
The remnant is not spherically symmetric, which is likely due to the progenitor being a runaway star system. The bow shock is caused by the interaction of the advancing stellar wind with the interstellar medium. A remnant rich in nitrogen and silicon indicates that the system consisted of a white dwarf with an evolved companion that had likely already passed through the asymptotic giant branch stage.
More information: NASA
and the treasures hidden in the heavens so rich,
precisely in order that the human mind
shall never be lacking in fresh nourishment.
Johannes Kepler
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