http://www.itmedia.co.jp/news/articles/1805/09/news089.html

https://www.asahi.com/articles/ASL5753TKL57UTIL02H.html

https://gigazine.net/news/20180509-sun-planetary-nebula/

https://www.nikkei.com/article/DGXMZO30145690X00C18A5SHA100/

https://headlines.yahoo.co.jp/hl?a=20180509-00000091-mai-soci