Dlouhodob\u00e1 astronomick\u00e1 pozorov\u00e1n\u00ed p\u0159in\u00e1\u0161ej\u00ed unik\u00e1tn\u00ed \u00fadaje pro studium zaj\u00edmav\u00fdch hv\u011bzdn\u00fdch syst\u00e9m\u016f. Kataklyzmick\u00e9 prom\u011bnn\u00e9 p\u0159edstavuj\u00ed fascinuj\u00edc\u00ed kategorii objekt\u016f. V t\u011bchto t\u011bsn\u00fdch syst\u00e9mech proud\u00ed hmota z jedn\u00e9 hv\u011bzdy \u2013 obvykle vyvinut\u00e9 chladn\u00e9 hv\u011bzdy \u2013 na druhou slo\u017eku, kterou b\u00fdv\u00e1 b\u00edl\u00fd trpasl\u00edk. Ob\u011b\u017en\u00e1 dr\u00e1ha je typicky n\u011bkolik hodin. U v\u011bt\u0161iny takov\u00fdch syst\u00e9m\u016f se vytv\u00e1\u0159\u00ed z proud\u00edc\u00ed hmoty kolem tohoto trpasl\u00edka akre\u010dn\u00ed disk, ale existuje zvl\u00e1\u0161tn\u00ed podt\u0159\u00edda, kde k tomu nedojde: tzv. polary. Nov\u00e1 studie porovn\u00e1v\u00e1 dva konkr\u00e9tn\u00ed polary \u2013 BY Camelopardalis a AR Ursae Majoris \u2013 a ukazuje, \u017ee p\u0159esto\u017ee pat\u0159\u00ed do stejn\u00e9 kategorie, jejich dlouhodob\u00e9 chov\u00e1n\u00ed se z\u00e1sadn\u011b li\u0161\u00ed.<\/p>\n\n\n\n
V polarech m\u00e1 b\u00edl\u00fd trpasl\u00edk tak siln\u00e9 magnetick\u00e9 pole, \u017ee proud\u00edc\u00ed hmota je p\u0159\u00edmo nav\u00e1d\u011bna na jeho magnetick\u00e9 p\u00f3ly a dopad\u00e1 v jejich bl\u00edzkosti. T\u00edmto mechanismem vznik\u00e1 charakteristick\u00e9 z\u00e1\u0159en\u00ed, kter\u00e9 lze pozorovat ve viditeln\u00e9 i rentgenov\u00e9 oblasti, a tak\u00e9 v\u00fdrazn\u00e1 prom\u011bnnost jasnosti na r\u016fzn\u00fdch \u010dasov\u00fdch \u0161k\u00e1l\u00e1ch. Polary mohou p\u0159ech\u00e1zet mezi tzv. klidn\u00fdmi a aktivn\u00edmi stavy, p\u0159i\u010dem\u017e se jejich jasnost dramaticky m\u011bn\u00ed. D\u00e9lka trv\u00e1n\u00ed tohoto stavu m\u016f\u017ee \u010dasto nab\u00fdvat hodnot od dn\u00ed do m\u011bs\u00edc\u016f.<\/p>\n\n\n\n
Polary jsou nav\u00edc objekty, kter\u00e9 umo\u017e\u0148uj\u00ed testovat fyziku akrece hmoty v extr\u00e9mn\u00edch podm\u00ednk\u00e1ch, kde magnetick\u00e9 s\u00edly soupe\u0159\u00ed s gravita\u010dn\u00edm spadem t\u00e9to hmoty. Krom\u011b toho p\u0159edstavuj\u00ed laboratorn\u00ed p\u0159\u00edklady hv\u011bzdn\u00e9 aktivity: tok hmoty z\u00e1vis\u00ed nejen na vlastnostech b\u00edl\u00e9ho trpasl\u00edka, ale tak\u00e9 na magnetick\u00e9 \u010dinnosti druh\u00e9, d\u00e1rcovsk\u00e9 slo\u017eky, kter\u00e1 m\u016f\u017ee b\u00fdt poseta hv\u011bzdn\u00fdmi skvrnami ovliv\u0148uj\u00edc\u00edmi proud\u011bn\u00ed hmoty. Pr\u00e1v\u011b proto se studium polar\u016f \u010dasto zam\u011b\u0159uje na ot\u00e1zku, pro\u010d u n\u011bkter\u00fdch syst\u00e9m\u016f p\u0159eva\u017euje dlouh\u00e9 obdob\u00ed vysok\u00e9 aktivity, zat\u00edmco jin\u00e9 tr\u00e1v\u00ed v\u011bt\u0161inu \u010dasu v utlumen\u00e9m, tzv. n\u00edzk\u00e9m stavu.<\/p>\n\n\n\n
\u010cl\u00e1nek Vojt\u011bcha \u0160imona ze Stel\u00e1rn\u00edho odd\u011blen\u00ed ASU se soust\u0159ed\u00ed na dva konkr\u00e9tn\u00ed polary: BY Camelopardalis (BY Cam) a AR Ursae Majoris (AR UMa). Oba objekty pat\u0159\u00ed do t\u00e9\u017ee kategorie, av\u0161ak vykazuj\u00ed zcela odli\u0161n\u00e9 dlouhodob\u00e9 projevy aktivity. Autor vyu\u017eil rozs\u00e1hl\u00e1 data z modern\u00edch p\u0159ehl\u00eddkov\u00fdch projekt\u016f (Zwicky Transient Facility, Catalina Real-time Transient Survey) i z historick\u00fdch fotografick\u00fdch archiv\u016f (digitalizovan\u00e9 fotografick\u00e9 desky DASCH). T\u00edm z\u00edskal \u010dasov\u00e9 \u0159ady pokr\u00fdvaj\u00edc\u00ed des\u00edtky let a mohl podrobit sv\u011bteln\u00e9 k\u0159ivky podrobn\u00e9 anal\u00fdze. V\u00fdsledkem je detailn\u00ed srovn\u00e1n\u00ed, kter\u00e9 p\u0159in\u00e1\u0161\u00ed nov\u00e9 poznatky o tom, jak prom\u011bnliv\u00e1 a rozmanit\u00e1 m\u016f\u017ee b\u00fdt akrece hmoty v magnetick\u00fdch kataklyzmick\u00fdch prom\u011bnn\u00fdch.<\/p>\n\n\n\n
pokra\u010dov\u00e1n\u00ed: web ASU<\/a><\/p>\n\n\n\n Popis obr\u00e1zku:<\/strong> Polar na ilustraci vytvo\u0159en\u00e9 generativn\u00ed um\u011blou inteligenc\u00ed na z\u00e1klad\u011b \u00fadaj\u016f z \u010dl\u00e1nku. Vytvo\u0159eno pomoc\u00ed OpenAI DALL-E.<\/em><\/p>\n\n\n\n <\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" Dlouhodob\u00e1 astronomick\u00e1 pozorov\u00e1n\u00ed p\u0159in\u00e1\u0161ej\u00ed unik\u00e1tn\u00ed \u00fadaje pro studium zaj\u00edmav\u00fdch hv\u011bzdn\u00fdch syst\u00e9m\u016f. Kataklyzmick\u00e9 prom\u011bnn\u00e9 p\u0159edstavuj\u00ed fascinuj\u00edc\u00ed kategorii objekt\u016f. V t\u011bchto t\u011bsn\u00fdch syst\u00e9mech proud\u00ed hmota z jedn\u00e9 hv\u011bzdy \u2013<\/p>\n","protected":false},"author":1,"featured_media":3471,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37,32],"tags":[],"class_list":["post-3469","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-horke-hvezdy","category-novinky"],"_links":{"self":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3469","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=3469"}],"version-history":[{"count":2,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3469\/revisions"}],"predecessor-version":[{"id":3473,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/posts\/3469\/revisions\/3473"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/media\/3471"}],"wp:attachment":[{"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/media?parent=3469"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/categories?post=3469"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stel.asu.cas.cz\/cs\/wp-json\/wp\/v2\/tags?post=3469"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Dal\u0161\u00ed informace<\/h4>\n\n\n\n
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