Prom\u011bnnost hv\u011bzd pat\u0159\u00ed k z\u00e1kladn\u00edm jev\u016fm, kter\u00e9 astronomov\u00e9 studuj\u00ed u\u017e d\u00e9le ne\u017e sto let. Na prvn\u00ed pohled se m\u016f\u017ee zd\u00e1t, \u017ee zm\u011bny jasnosti hv\u011bzd jsou chaotick\u00e9 nebo nepravideln\u00e9, ale ve skute\u010dnosti se \u010dasto \u0159\u00edd\u00ed velmi p\u0159esn\u00fdmi z\u00e1konitostmi. Jedn\u00edm z nejb\u011b\u017en\u011bj\u0161\u00edch typ\u016f je periodick\u00e1 prom\u011bnnost, kdy se jas hv\u011bzdy m\u011bn\u00ed pravideln\u011b v \u010dase. Takov\u00e9 zm\u011bny mohou m\u00edt r\u016fzn\u00e9 fyzik\u00e1ln\u00ed p\u0159\u00ed\u010diny: hv\u011bzda m\u016f\u017ee pulzovat (tedy rytmicky se rozp\u00ednat a smr\u0161\u0165ovat), m\u016f\u017ee rotovat a n\u00e9st na sv\u00e9m povrchu tmav\u0161\u00ed nebo jasn\u011bj\u0161\u00ed oblasti (hv\u011bzdn\u00e9 skvrny). Nebo m\u016f\u017ee b\u00fdt sou\u010d\u00e1st\u00ed dvojhv\u011bzdy, kde se dv\u011b hv\u011bzdy ob\u00edhaj\u00ed. I kdy\u017e se nezakr\u00fdvaj\u00ed, pozorujeme u n\u011bkter\u00fdch t\u011bsn\u00fdch dvojhv\u011bzd sv\u011bteln\u00e9 zm\u011bny, kter\u00e9 jsou d\u016fsledkem gravita\u010dn\u00edho ztemn\u011bn\u00ed, slapov\u00fdch deformac\u00ed povrch\u016f hv\u011bzd i jejich vz\u00e1jemn\u00e9ho osv\u011btlov\u00e1n\u00ed.<\/p>\n\n\n\n
Zvl\u00e1\u0161\u0165 zaj\u00edmav\u00e9 jsou p\u0159\u00edpady, kdy se jas m\u011bn\u00ed t\u00e9m\u011b\u0159 dokonale sinusov\u011b \u2013 tedy jako hladk\u00e1 vlna bez v\u00fdrazn\u00fdch deformac\u00ed. Takov\u00e9 sv\u011bteln\u00e9 k\u0159ivky jsou na prvn\u00ed pohled \u201ejednoduch\u00e9\u201c, ale pr\u00e1v\u011b proto jsou zr\u00e1dn\u00e9: r\u016fzn\u00e9 fyzik\u00e1ln\u00ed mechanismy mohou vytv\u00e1\u0159et velmi podobn\u00fd sign\u00e1l. To komplikuje klasifikaci hv\u011bzd na z\u00e1klad\u011b samotn\u00fdch fotometrick\u00fdch dat, tedy m\u011b\u0159en\u00ed jasnosti. Modern\u00ed kosmick\u00e9 mise, jako je dru\u017eice TESS, poskytuj\u00ed obrovsk\u00e9 mno\u017estv\u00ed p\u0159esn\u00fdch dat o jasnosti hv\u011bzd, ale bez dopl\u0148uj\u00edc\u00edch informac\u00ed (nap\u0159\u00edklad ze spekter) je \u010dasto nemo\u017en\u00e9 jednozna\u010dn\u011b ur\u010dit, co p\u0159esn\u011b variabilitu zp\u016fsobuje.<\/p>\n\n\n\n
Studovan\u00fd \u010dl\u00e1nek, v n\u011bm\u017e d\u016fle\u017eitou roli hr\u00e1l i Marek Skarka ze Stel\u00e1rn\u00edho odd\u011blen\u00ed ASU, se zam\u011b\u0159uje na hork\u00e9 hv\u011bzdy hlavn\u00ed posloupnosti spektr\u00e1ln\u00edch typ\u016f F a\u017e O, tedy hv\u011bzdy teplej\u0161\u00ed ne\u017e zhruba 6500 K. Tyto objekty maj\u00ed odli\u0161nou vnit\u0159n\u00ed strukturu ne\u017e chladn\u011bj\u0161\u00ed hv\u011bzdy typu Slunce \u2013 jejich ob\u00e1lky jsou p\u0159ev\u00e1\u017en\u011b v z\u00e1\u0159iv\u00e9 rovnov\u00e1ze, co\u017e znamen\u00e1, \u017ee zde neprob\u00edh\u00e1 siln\u00e1 konvekce. Proto se dlouho p\u0159edpokl\u00e1dalo, \u017ee nemohou m\u00edt v\u00fdrazn\u00e9 povrchov\u00e9 skvrny, kter\u00e9 jsou \u010dast\u011bji spojov\u00e1ny s podpovrchovou konvekc\u00ed. Nov\u011bj\u0161\u00ed v\u00fdzkumy v\u0161ak nazna\u010duj\u00ed, \u017ee i tyto hv\u011bzdy mohou vykazovat rota\u010dn\u00ed modulaci nebo jin\u00e9 komplexn\u00ed jevy. Pr\u00e1v\u011b proto je d\u016fle\u017eit\u00e9 detailn\u011b zkoumat, co stoj\u00ed za jejich zd\u00e1nliv\u011b jednoduchou sinusovou prom\u011bnnost\u00ed.<\/p>\n\n\n\n
\u00davodn\u00ed obr\u00e1zek<\/strong>: P\u0159\u00edpad hv\u011bzd TIC 21673730 (naho\u0159e) a TIC 61449214 (dole). Pokud bychom uv\u00e1\u017eili jen sv\u011bteln\u00e9 k\u0159ivky (v\u017edy horn\u00ed panely), nem\u011bli bychom \u0161anci odli\u0161it, zda je o rota\u010dn\u00ed prom\u011bnnou hv\u011bzdu s p\u0159etrv\u00e1vaj\u00edc\u00edmi skvrnami na povrchu nebo o dvojhv\u011bzdu. V\u0161e odhal\u00ed k\u0159ivka radi\u00e1ln\u00edch rychlost\u00ed (v\u017edy spodn\u00ed panely). Vlevo je slo\u017een\u00e1 k\u0159ivka s jednon\u00e1sobkem nebo dvojn\u00e1sobkem dominantn\u00ed periody. Ta ukazuje, \u017ee s dvojn\u00e1sobkem periody vykresl\u00ed k\u0159ivka radi\u00e1ln\u00edch rychlost\u00ed u hv\u011bzdy TIC 21673730 uk\u00e1zkov\u00fd cyklus \u2013 jde tedy o dvojhv\u011bzdu s jednou slo\u017ekou viditelnou ve spektru. Naproti tomu u hv\u011bzdy TIC 61449214 se nic v\u00fdzna\u010dn\u00e9ho nezm\u011bn\u00ed a radi\u00e1ln\u00ed rychlosti osciluj\u00ed kolem nuly. Jde tedy o rota\u010dn\u00ed prom\u011bnnost.<\/em><\/p>\n\n\n\n Pokra\u010dov\u00e1n\u00ed: web ASU<\/a><\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" Prom\u011bnnost hv\u011bzd pat\u0159\u00ed k z\u00e1kladn\u00edm jev\u016fm, kter\u00e9 astronomov\u00e9 studuj\u00ed u\u017e d\u00e9le ne\u017e sto let. Na prvn\u00ed pohled se m\u016f\u017ee zd\u00e1t, \u017ee zm\u011bny jasnosti hv\u011bzd jsou chaotick\u00e9<\/p>\n","protected":false},"author":1,"featured_media":3754,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38,32,43],"tags":[],"class_list":["post-3752","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-exoplanety","category-novinky","category-perek-2m"],"_links":{"self":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3752","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/comments?post=3752"}],"version-history":[{"count":2,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3752\/revisions"}],"predecessor-version":[{"id":3755,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3752\/revisions\/3755"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/media\/3754"}],"wp:attachment":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/media?parent=3752"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/categories?post=3752"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/tags?post=3752"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n\n\n\nDal\u0161\u00ed informace<\/h3>\n\n\n\n
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