{"id":978,"date":"2004-11-15T14:43:00","date_gmt":"2004-11-15T13:43:00","guid":{"rendered":"https:\/\/kids.esa.int\/star_death\/"},"modified":"2026-10-08T00:34:26","modified_gmt":"2026-10-07T22:34:26","slug":"star_death","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/star_death\/","title":{"rendered":"T\u00e4hden kuolema"},"content":{"rendered":"
\n

Useimpien t\u00e4htien kuoleminen kest\u00e4\u00e4 miljoonia vuosia. Kun Aurinkoa muistuttava t\u00e4hti on polttanut kaiken vetypolttoaineensa, se laajenee ja muuttuu punaiseksi j\u00e4ttil\u00e4iseksi. Sen halkaisija voi olla miljoonia kilometrej\u00e4 \u2013 tarpeeksi suuri nielaisemaan Merkurius- ja Venus-planeetat.<\/p>\n<\/div>\n

Kun t\u00e4hti on puhaltanut ulkokerroksensa pois, se romahtaa ja muodostaa eritt\u00e4in tihe\u00e4n valkoisen k\u00e4\u00e4pi\u00f6n. Yksi teelusikallinen valkoisen k\u00e4\u00e4pi\u00f6n ainetta painaisi jopa 100 tonnia. Miljardien vuosien kuluessa valkoinen k\u00e4\u00e4pi\u00f6 j\u00e4\u00e4htyy ja muuttuu n\u00e4kym\u00e4tt\u00f6m\u00e4ksi.<\/p>\n

T\u00e4hdet, joiden massa on yli kahdeksan kertaa Auringon massa, p\u00e4\u00e4ttyv\u00e4t hyvin \u00e4killisesti. Kun niiden polttoaine loppuu, ne turpoavat punaisiksi superj\u00e4ttil\u00e4isiksi. Ne yritt\u00e4v\u00e4t pysy\u00e4 hengiss\u00e4 polttamalla erilaisia polttoaineita, mutta t\u00e4m\u00e4 onnistuu vain muutaman miljoonan vuoden ajan. Sitten ne r\u00e4j\u00e4ht\u00e4v\u00e4t palasiksi valtavassa supernovar\u00e4j\u00e4hdyksess\u00e4.<\/p>\n

Noin viikon ajan supernova loistaa kirkkaammin kuin mik\u00e4\u00e4n muu t\u00e4hti galaksissaan. Sitten sen kirkkaus hiipuu nopeasti. J\u00e4ljelle j\u00e4\u00e4 vain pieni, tihe\u00e4 kappale \u2013 neutronit\u00e4hti tai musta aukko \u2013 jota ymp\u00e4r\u00f6i laajeneva, eritt\u00e4in kuuman kaasun pilvi.<\/p>\n

Superj\u00e4ttil\u00e4ist\u00e4hdess\u00e4 muodostuneet alkuaineet (kuten happi, hiili ja rauta) levi\u00e4v\u00e4t avaruuteen. T\u00e4st\u00e4 t\u00e4htip\u00f6lyst\u00e4 syntyy lopulta uusia t\u00e4hti\u00e4 ja planeettoja.<\/p>","protected":false},"excerpt":{"rendered":"

Most stars take millions of years to die. When a star like the Sun has burned all of its hydrogen fuel, it expands to become a red giant. This may […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"esa_banner_image":"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2003\/05\/ngc_6369_a_cosmic_ghost2\/17884213-2-eng-GB\/NGC_6369_a_cosmic_ghost.jpg","esa_banner_description":"NGC 6369, a cosmic ghost","esa_banner_credit":"NASA and The Hubble Heritage Team (STScI\/AURA)","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2003\/05\/NGC_6369_a_cosmic_ghost2","esa_external_url":"","esa_external_new_window":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":true},"categories":[10,11,21],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-978","post","type-post","status-publish","format-standard","hentry","category-learn","category-our-universe","category-stars-and-galaxies","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/978","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/comments?post=978"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/978\/revisions"}],"predecessor-version":[{"id":2121,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/978\/revisions\/2121"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=978"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=978"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=978"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=978"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=978"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=978"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=978"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=978"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=978"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=978"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}