Editing Kepler's Supernova (section)

== Supernova remnant ==
[[File:Kepler's Supernova Remnant- A Star's Death Comes to Life (2941498208).jpg|right|thumb|X-ray image of SN 1604 from the [[Chandra X-ray Observatory]]]]
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 [[Magnitude (astronomy)|mag]].<ref name="baade">{{Cite journal|doi = 10.1086/144505|title = Nova Ophiuchi of 1604 AS a Supernova|year = 1943|last1 = Baade|first1 = W.|journal = The Astrophysical Journal|volume = 97|page = 119|bibcode = 1943ApJ....97..119B|doi-access = free}}</ref> 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),<ref name="patnaude12">{{cite journal |doi=10.1088/0004-637X/756/1/6 |arxiv=1206.6799|title=The Origin of Kepler's Supernova Remnant|year=2012|last1=Patnaude|first1=Daniel J.|last2=Badenes|first2=Carles|last3=Park|first3=Sangwook|last4=Laming|first4=J. Martin|journal=The Astrophysical Journal|volume=756|issue=1|page=6|bibcode=2012ApJ...756....6P|s2cid=119104810}}</ref> with the current consensus being a distance of {{val|5|1|u=kpc}}, as of 2021.<ref name=Kasuga_et_al_2021/>

The available evidence supports a [[type Ia supernova]] as the source of this remnant,<ref name="chandra"/> which is the result of a carbon-oxygen [[white dwarf]] interacting with a companion star.<ref name=Chiotellis_et_al_2020/> 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 supernova|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.<ref name="chandra"/>

There is evidence for interaction of the supernova ejecta with circumstellar matter from the [[Progenitor|progenitor star]], which is unexpected for type Ia but has been observed in some cases.<ref name="chandra"/> A [[bow shock]] located to the north of this system is believed to have been created by mass loss prior to the explosion.<ref name="patnaude12"/> 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.<ref name=Chiotellis_et_al_2020>{{cite journal | title=The Interaction of Type Ia Supernovae with Planetary Nebulae: The Case of Kepler's Supernova Remnant | last1=Chiotellis | first1=A. | last2=Boumis | first2=P. | last3=Spetsieri | first3=Z. T. | journal=Galaxies | volume=8 | issue=2 | page=38 | date=May 2020 | doi=10.3390/galaxies8020038 | arxiv=2004.14493 | bibcode=2020Galax...8...38C | doi-access=free }}</ref> The remnant is not spherically symmetric, which is likely due to the progenitor being a [[High-velocity star|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.<ref name=Kasuga_et_al_2021>{{cite journal | title=Spatially Resolved RGS Analysis of Kepler's Supernova Remnant | last1=Kasuga | first1=Tomoaki | last2=Vink | first2=Jacco | last3=Katsuda | first3=Satoru | last4=Uchida | first4=Hiroyuki | last5=Bamba | first5=Aya | last6=Sato | first6=Toshiki | last7=Hughes | first7=John P. | journal=The Astrophysical Journal | volume=915 | issue=1 | id=42 | date=July 2021 | page=42 | doi=10.3847/1538-4357/abff4f | arxiv=2105.04235 | bibcode=2021ApJ...915...42K | s2cid=234336681 | doi-access=free }}</ref>