{"id":1677,"date":"2015-01-13T16:28:31","date_gmt":"2015-01-13T14:28:31","guid":{"rendered":"http:\/\/bilimvegelecek.com.tr\/?p=1677"},"modified":"2015-01-13T16:28:31","modified_gmt":"2015-01-13T14:28:31","slug":"yildizlarin-donus-hizlari-yaslarini-veriyor","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2015\/01\/13\/yildizlarin-donus-hizlari-yaslarini-veriyor","title":{"rendered":"Y\u0131ld\u0131zlar\u0131n d\u00f6n\u00fc\u015f h\u0131zlar\u0131 ya\u015flar\u0131n\u0131 veriyor"},"content":{"rendered":"

G\u00f6rsel a\u00e7\u0131klamas\u0131:<\/strong> Gen\u00e7 y\u0131ld\u0131zlar\u0131n ya\u015flar\u0131n\u0131 s\u00f6ylemek kolayd\u0131r, \u00e7\u00fcnk\u00fc onlar daha h\u0131zl\u0131 d\u00f6nerler ve daha b\u00fcy\u00fck g\u00fcne\u015f lekelerine sahiplerdir. Foto\u011fraf: David A. Aguilar (CfA)<\/em><\/p>\n

\u00c7ocukken her do\u011fum g\u00fcn\u00fc, kutlama yapmak i\u00e7in bir nedendir, fakat b\u00fcy\u00fcd\u00fc\u011f\u00fcn\u00fczde bu heyecan biraz azal\u0131r. Y\u0131llar i\u00e7inde yava\u015flad\u0131\u011f\u0131n\u0131z\u0131 fark eder ve ya\u015fland\u0131\u011f\u0131n\u0131z\u0131 kabul etmek istemezsiniz. Yaln\u0131z de\u011filsiniz; bu durum y\u0131ld\u0131zlar i\u00e7in de ayn\u0131. Onlar da y\u0131llar ge\u00e7tik\u00e7e yava\u015fl\u0131yorlar ve ya\u015flar\u0131 iyi koruduklar\u0131 s\u0131rlar\u0131d\u0131r. Astronomlar, y\u0131ld\u0131zlar\u0131n hareket h\u0131zlar\u0131n\u0131 tespit ederek, ya\u015flar\u0131n\u0131 \u00e7\u00f6zmeye \u00e7al\u0131\u015f\u0131yor.
\nHarvard-Smithsonian Merkezi Astrofizik B\u00f6l\u00fcm\u00fc\u2019nden Soren Meibom, y\u0131ld\u0131zlar\u0131n d\u00f6n\u00fc\u015f\u00fcnden, onlar\u0131n ya\u015flar\u0131na dair kesin ve hassas \u00f6l\u00e7\u00fcmler yapabilecek bir saat olu\u015fturmay\u0131 ama\u00e7lad\u0131klar\u0131n\u0131 s\u00f6yl\u00fcyor. Saatin yap\u0131m\u0131nda \u00f6nemli bir ad\u0131m atm\u0131\u015flar. Ge\u00e7ti\u011fimiz g\u00fcnlerde Amerikan Astronomi Toplulu\u011fu toplant\u0131s\u0131nda \u00e7al\u0131\u015fmalar\u0131n\u0131 sunan Meibom ve ekibinin sonu\u00e7lar\u0131, 1 milyar y\u0131l ya\u015f\u0131nda olan y\u0131ld\u0131zlardan 4 milyar y\u0131ll\u0131k G\u00fcne\u015f\u2019in ya\u015f\u0131na dek g\u00f6zlenen y\u0131ld\u0131zlar\u0131 i\u00e7eriyor.
\nMeibom, \u201cY\u0131ld\u0131zlar\u0131n ya\u015f\u0131n\u0131 s\u00f6yleyebilmek, y\u0131ld\u0131zlar\u0131n evrimini ve bile\u015fenlerinin zaman i\u00e7erisinde ortaya \u00e7\u0131kmas\u0131n\u0131 i\u00e7eren astrofizik olaylar\u0131n\u0131n anla\u015f\u0131labilmesi i\u00e7in bir temel olu\u015fturuyor. Ayr\u0131ca, bu bilgiler, G\u00fcne\u015f Sistemimizin d\u0131\u015f\u0131nda ba\u015fka bir hayat olup olmad\u0131\u011f\u0131na dair ara\u015ft\u0131rma yapmakla da k\u0131smen alakal\u0131d\u0131r. Astronomlar, kesin \u00f6l\u00e7\u00fcm yapan y\u0131ld\u0131z saatiyle, y\u0131ld\u0131zlarla birlikte daha ya\u015fl\u0131 gezegenlerin de ya\u015f\u0131n\u0131 belirleyebilecekler.\u201d
\nY\u0131ld\u0131zlar\u0131n d\u00f6n\u00fc\u015f h\u0131z\u0131 ya\u015flar\u0131na ba\u011fl\u0131d\u0131r, \u00e7\u00fcnk\u00fc zamanla sabit bir \u015fekilde yava\u015flarlar. Ama ayn\u0131 zamanda k\u00fctlelerine de ba\u011fl\u0131d\u0131r. Astronomlar b\u00fcy\u00fck ve a\u011f\u0131r y\u0131ld\u0131zlar\u0131n k\u00fc\u00e7\u00fck ve hafif olanlara g\u00f6re daha h\u0131zl\u0131 d\u00f6nme e\u011filiminde oldu\u011funu buldu. Bu \u00e7al\u0131\u015fmayla, k\u00fctle, d\u00f6nme ve ya\u015f aras\u0131nda kapal\u0131 matematiksel bir ili\u015fki oldu\u011funu g\u00f6sterdi. B\u00f6ylece biliminsanlar\u0131 ilk ikisinin \u00f6l\u00e7\u00fclmesiyle \u00fc\u00e7\u00fcnc\u00fcy\u00fc hesaplayabilecekler.
\n\u00c7al\u0131\u015fman\u0131n di\u011fer yazar\u0131 Almanya\u2019daki Leibniz Enstit\u00fcs\u00fc Astrofizik B\u00f6l\u00fcm\u00fc\u2019nden Sydney Barnes k\u00fctle, d\u00f6nme h\u0131z\u0131 ve ya\u015f aras\u0131nda bulduklar\u0131 ili\u015fkinin g\u00f6zlemlerle de tan\u0131mland\u0131\u011f\u0131n\u0131 belirtiyor. Barnes ilk olarak bu y\u00f6ntemi 2003\u2019de tasarlam\u0131\u015f; Yunanca d\u00f6nme anlam\u0131na \u201cgelengyros\u201d, zaman\/ya\u015f anlam\u0131na gelen \u201cchronos\u201d ve \u00e7al\u0131\u015fma anlam\u0131na gelen \u201cstudy\u201d s\u00f6zc\u00fcklerini birle\u015ftirerek \u201cgyrochronology\u201d ad\u0131n\u0131 vermi\u015f.
\nAstronomlar, bir y\u0131ld\u0131z\u0131n d\u00f6n\u00fc\u015f\u00fcn\u00fc \u00f6l\u00e7ebilmek i\u00e7in onun y\u00fczeyindeki kara lekelerin neden oldu\u011fu parlakl\u0131k de\u011fi\u015fimini inceliyor. G\u00fcne\u015fimizin aksine uzak bir y\u0131ld\u0131z, \u0131\u015f\u0131\u011f\u0131n ayr\u0131\u015fmad\u0131\u011f\u0131 bir noktad\u0131r. Bu y\u00fczden, astronomlar y\u0131ld\u0131z diskinin \u00e7evresinde do\u011frudan bir g\u00fcne\u015f lekesi g\u00f6zleyemezler. Bunun yerine, g\u00fcne\u015f lekesi g\u00f6rd\u00fcklerinde, izledikleri y\u0131ld\u0131z\u0131n \u0131\u015f\u0131\u011f\u0131 yava\u015f\u00e7a azal\u0131r ve g\u00fcne\u015f lekesi d\u00f6n\u00fc\u015f nedeniyle g\u00f6r\u00fc\u015f a\u00e7\u0131lar\u0131ndan uzakla\u015ft\u0131\u011f\u0131nda tekrar ayd\u0131nlan\u0131r. Bu de\u011fi\u015fiklikleri \u00f6l\u00e7mek \u00e7ok zordur, \u00e7\u00fcnk\u00fc tipik bir y\u0131ld\u0131z\u0131n \u0131\u015f\u0131\u011f\u0131 y\u00fczde 1\u2019den daha az azal\u0131r ve y\u0131ld\u0131z\u0131n y\u00fcz\u00fcnde bir g\u00fcne\u015f lekesi g\u00f6rmek g\u00fcnler alabilir. \u00c7al\u0131\u015fma grubu bu olay\u0131, y\u0131ld\u0131z parlakl\u0131klar\u0131n\u0131 hassas ve s\u00fcrekli \u00f6l\u00e7\u00fcmlerle sa\u011flayan, verilerini NASA\u2019dan ald\u0131klar\u0131, Kepler uzay arac\u0131n\u0131n \u00f6l\u00e7\u00fcmlerini kullanarak ba\u015fard\u0131.
\nAstronomlar, \u201cgyrochronology\u201d ya\u015flar\u0131n\u0131n kesin ve hassas olmas\u0131 i\u00e7in y\u0131ld\u0131zlar\u0131n d\u00f6nme periyotlar\u0131n\u0131 ya\u015flar\u0131 ve k\u00fctleleriyle beraber \u00f6l\u00e7erek yeni saatlerini kalibre etmeliler. Meibom ve meslekta\u015flar\u0131 \u00f6nceden bir milyar y\u0131ll\u0131k y\u0131ld\u0131z topluluklar\u0131 \u00fczerinde \u00e7al\u0131\u015f\u0131yorlard\u0131. Yeni \u00e7al\u0131\u015fma NGC 6819 olarak bilinen 2, 5 milyar y\u0131l ya\u015f\u0131ndaki y\u0131ld\u0131z k\u00fcmelerini inceliyor. B\u00f6ylelikle, ya\u015f aral\u0131\u011f\u0131n\u0131n \u00f6nemli \u00f6l\u00e7\u00fcde geni\u015fledi\u011fi s\u00f6ylenebilir. Meibom ya\u015fl\u0131 y\u0131ld\u0131zlar\u0131n az ve ufak lekelere sahip oldu\u011funu ve onlar\u0131n periyodunu belirlemenin zor oldu\u011funu s\u00f6yl\u00fcyor.
\n\u00c7al\u0131\u015fma grubu, G\u00fcne\u015fin a\u011f\u0131rl\u0131\u011f\u0131n\u0131n y\u00fczde 80 ile y\u00fczde 140\u2019\u0131 kadar a\u011f\u0131rl\u0131\u011fa sahip y\u0131ld\u0131zlar\u0131 inceledi. D\u00f6nme periyodu 26 g\u00fcn olan G\u00fcne\u015f\u2019e k\u0131yasla, periyotlar\u0131 4 g\u00fcnden 23 g\u00fcne kadar olan 30 y\u0131ld\u0131z\u0131n d\u00f6nmesini \u00f6l\u00e7ebildiler. G\u00fcne\u015f ile \u00e7ok benzeyen, NGC 6819 k\u00fcmesindeki, sekiz y\u0131ld\u0131z ortalama olarak 18, 2 g\u00fcnl\u00fck d\u00f6nme periyoduna sahiptir. Buradan, G\u00fcne\u015f\u2019in periyodunun yakla\u015f\u0131k 2 milyar y\u0131l \u00f6ncesine ait oldu\u011funu \u00e7\u0131karabiliriz.
\n\u00c7al\u0131\u015fma grubu, \u00f6l\u00e7\u00fcmlerle en iyi e\u015fle\u015fen modelin belirlendi\u011fi, y\u0131ld\u0131zlar\u0131n k\u00fctlelerine ve ya\u015flar\u0131na ba\u011fl\u0131 olarak d\u00f6n\u00fc\u015f h\u0131zlar\u0131n\u0131n hesapland\u0131\u011f\u0131 bir\u00e7ok bilgisayarl\u0131 modelleme geli\u015ftirdi. Meibom, d\u00f6n\u00fc\u015f periyotlar\u0131n\u0131n \u00f6l\u00e7\u00fclmesiyle, bizim galaksimizdeki \u00e7ok say\u0131daki so\u011fuk b\u00f6lge y\u0131ld\u0131zlar\u0131 i\u00e7in kesin bir ya\u015f elde edilebilece\u011fini belirtiyor. Ortaya konan bu ara\u015ft\u0131rma, Meibom\u2019un geni\u015f Kepler k\u00fcme \u00e7al\u0131\u015fmas\u0131n\u0131n bir par\u00e7as\u0131d\u0131r.<\/p>\n

\u00c7eviren: Eda K\u0131l\u0131n\u00e7arslan<\/strong>
\n\u0130T\u00dc Fizik M\u00fchendisli\u011fi YL \u00d6\u011frencisi<\/strong><\/em><\/p>\n

Kaynak:<\/strong> http:\/\/www.sciencedaily.com\/releases\/2015\/01\/150105141651.htm<\/p>\n

Dergi referans\u0131:<\/strong> S\u00f8ren Meibom, Sydney A. Barnes, ImantsPlatais, Ronald L. Gilliland, David W. Latham, Robert D. Mathieu, \u201cA spin-downclock for cool stars from observations of a 2.5-billion-year-oldcluster\u201d, Nature, 2015; DOI: 10.1038\/nature14118<\/p>\n","protected":false},"excerpt":{"rendered":"

G\u00f6rsel a\u00e7\u0131klamas\u0131: Gen\u00e7 y\u0131ld\u0131zlar\u0131n ya\u015flar\u0131n\u0131 s\u00f6ylemek kolayd\u0131r, \u00e7\u00fcnk\u00fc onlar daha h\u0131zl\u0131 d\u00f6nerler ve daha b\u00fcy\u00fck g\u00fcne\u015f lekelerine sahiplerdir. Foto\u011fraf: David A. Aguilar (CfA) \u00c7ocukken her do\u011fum g\u00fcn\u00fc, kutlama yapmak i\u00e7in bir nedendir, fakat b\u00fcy\u00fcd\u00fc\u011f\u00fcn\u00fczde bu heyecan biraz azal\u0131r. Y\u0131llar i\u00e7inde yava\u015flad\u0131\u011f\u0131n\u0131z\u0131 fark eder ve ya\u015fland\u0131\u011f\u0131n\u0131z\u0131 kabul etmek istemezsiniz. Yaln\u0131z de\u011filsiniz; bu durum y\u0131ld\u0131zlar i\u00e7in de […]<\/p>\n","protected":false},"author":1,"featured_media":1678,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[30,19],"tags":[],"class_list":["post-1677","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-astronomi","category-bilim-gundemi"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/1677","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/comments?post=1677"}],"version-history":[{"count":0,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/1677\/revisions"}],"wp:attachment":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media?parent=1677"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/categories?post=1677"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/tags?post=1677"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}