{"id":33131,"date":"2019-03-11T04:10:26","date_gmt":"2019-03-11T01:10:26","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=33131"},"modified":"2019-03-11T03:16:23","modified_gmt":"2019-03-11T00:16:23","slug":"galaksimiz-samanyolunun-agirligini-ogrenmek-ister-misiniz","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2019\/03\/11\/galaksimiz-samanyolunun-agirligini-ogrenmek-ister-misiniz","title":{"rendered":"Galaksimiz Samanyolu\u2019nun a\u011f\u0131rl\u0131\u011f\u0131n\u0131 \u00f6\u011frenmek ister misiniz?"},"content":{"rendered":"

Samanyolu’nu teraziye koyup tartamay\u0131z elbette; fakat g\u00f6kbilimciler NASA’n\u0131n Hubble Uzay Teleskobu ile Avrupa Uzay Ajans\u0131’n\u0131n Gaia uydusunu kullanarak galaksimizin k\u00fctlesini en do\u011fru \u015fekilde \u00f6l\u00e7menin yolunu buldu. Son hesaplamalara g\u00f6re Samanyolu’nun a\u011f\u0131rl\u0131\u011f\u0131 yakla\u015f\u0131k 1,5 trilyon G\u00fcne\u015f k\u00fctlesi kadar (1 birim G\u00fcne\u015f k\u00fctlesi G\u00fcne\u015f\u2019in a\u011f\u0131rl\u0131\u011f\u0131na denk). Bu k\u00fctlenin \u00e7ok k\u00fc\u00e7\u00fck bir y\u00fczdesi Samanyolu’nda say\u0131lar\u0131 200 milyar\u0131 bulan y\u0131ld\u0131za ve galaksinin merkezinde bulunan 4 milyon G\u00fcne\u015f k\u00fctlelik kara deli\u011fe ait. Kalan k\u0131sm\u0131n yakla\u015f\u0131k %90\u2019\u0131 adeta evrenin iskeleti rol\u00fcn\u00fc oynayan ve y\u0131ld\u0131zlar\u0131 galaksideki sabit konumunda tutan, g\u00f6r\u00fcnmez ve gizemli, karanl\u0131k madde denen yap\u0131n\u0131n i\u00e7ine hapsolmu\u015f durumda.<\/span><\/p>\n

Y\u0131llard\u0131r devam eden ara\u015ft\u0131rmalarda de\u011fi\u015fik g\u00f6zlem y\u00f6ntemleri kullan\u0131lm\u0131\u015f ve galaksimizin k\u00fctlesinin 500 milyar ila 3 trilyon G\u00fcne\u015f k\u00fctlesi aras\u0131nda bir yerlerde oldu\u011fu sonucuna var\u0131lm\u0131\u015ft\u0131. Daha ileri tekniklerle ula\u015f\u0131lan mevcut \u00f6l\u00e7\u00fcm ise bu aral\u0131\u011f\u0131n ortas\u0131na tekab\u00fcl ediyor. Hesaplamalar aras\u0131ndaki farkl\u0131l\u0131k da zaten karanl\u0131k maddenin da\u011f\u0131l\u0131m\u0131 ile ilgili \u00f6l\u00e7\u00fcm fark\u0131ndan kaynaklan\u0131yor. \u00c7al\u0131\u015fman\u0131n y\u00fcr\u00fct\u00fcc\u00fclerinden, Almanya’daki Avrupa G\u00fcney G\u00f6zlemevi ara\u015ft\u0131rmac\u0131lar\u0131ndan Laura Watkins \u00f6l\u00e7\u00fcm y\u00f6ntemleri ile ili\u015fkili bu fark\u0131 \u015f\u00f6yle a\u00e7\u0131kl\u0131yor: \u201cKaranl\u0131k maddeyi do\u011frudan tespit edemiyoruz. G\u00f6remedi\u011fimiz bir \u015feyi tam olarak \u00f6l\u00e7me \u015fans\u0131n\u0131z da olmaz. Samanyolu k\u00fctlesindeki mevcut belirsizli\u011fe neden olan tam da bu.\u201d<\/span><\/p>\n

\u015eimdi ise k\u00fctleye dair yeni hesaplamalar evrendeki di\u011fer galaksilere k\u0131yasla bizi hacimli tarafa yerle\u015ftiriyor. En hafif galaksilerin G\u00fcne\u015f k\u00fctlesi cinsinden a\u011f\u0131rl\u0131\u011f\u0131 1 milyar civar\u0131nda; en a\u011f\u0131rlar ise bundan 30.000 kat daha fazla yani 30 trilyon G\u00fcne\u015f k\u00fctlesi kadarlar. 1,5 trilyon G\u00fcne\u015f k\u00fctlesi \u00e7ap\u0131ndaki a\u011f\u0131rl\u0131k bu parlakl\u0131ktaki bir galaksi i\u00e7in beklenen bir sonu\u00e7. Hesaplamalar\u0131nda g\u00f6kbilimciler Hubble ve Gaia arac\u0131l\u0131\u011f\u0131yla k\u00fcresel y\u0131ld\u0131z k\u00fcmeleri denen olu\u015fumlar\u0131n \u00fc\u00e7 boyutlu hareketlerini \u00f6l\u00e7t\u00fcler; bu k\u00fcmelerin her biri galaksinin merkezi etraf\u0131nda d\u00f6nen, binlerce y\u0131ld\u0131zdan olu\u015fmu\u015f tecrit halindeki k\u00fcresel adalardan meydana geliyor. G\u00f6zle g\u00f6r\u00fclmesi m\u00fcmk\u00fcn olmasa da maddenin evrendeki en yayg\u0131n formu olan karanl\u0131k madde, k\u00fcresel k\u00fcmeler gibi g\u00f6r\u00fclebilir nesneler \u00fczerinde belli bir etki g\u00f6steriyor. \u00d6yle ki galaksi ne kadar b\u00fcy\u00fckse b\u00fcnyesindeki k\u00fcresel k\u00fcmeler de k\u00fctle\u00e7ekiminin etkisiyle o denli h\u0131zl\u0131 hareket ediyor. \u00d6nceki hesaplamalardan g\u00f6kbilimciler k\u00fcresel k\u00fcmelerin hangi h\u0131zla D\u00fcnya\u2019ya yakla\u015ft\u0131klar\u0131n\u0131 ya da uzakla\u015ft\u0131klar\u0131n\u0131 biliyorlar. Bunlar g\u00f6zlem alan\u0131m\u0131z i\u00e7indeki h\u0131za kar\u015f\u0131l\u0131k geliyor. Ancak Hubble ve Gaia sayesinde k\u00fcresel k\u00fcmelerin bu alan\u0131n d\u0131\u015f\u0131nda kalan k\u0131s\u0131mlardaki hareketi de b\u00fcy\u00fck bir kesinlikle hesaplanabildi. Buradan da toplam galaksi k\u00fctlesine dair \u00e7\u0131kar\u0131mlara gidildi.<\/span><\/p>\n

\u0130\u015fin g\u00fczel taraf\u0131 Hubble ve Gaia arac\u0131l\u0131\u011f\u0131yla yap\u0131lan g\u00f6zlemler birbirini tamaml\u0131yor. Gaia \u00a0Samanyolu’ndaki g\u00f6kcisimlerinin \u00fc\u00e7 boyutlu haritas\u0131n\u0131 olu\u015fturmak ve hareketlerin takibi i\u00e7in tasarlanm\u0131\u015ft\u0131. Bu da g\u00f6ky\u00fcz\u00fc tabanl\u0131 t\u00fcm \u00f6l\u00e7\u00fcmleri \u00e7ok daha kesin bir zemine oturttu. Hubble ise g\u00f6r\u00fc\u015f alan\u0131 bak\u0131m\u0131ndan daha az kapsay\u0131c\u0131, fakat \u00e7ok daha s\u00f6n\u00fck y\u0131ld\u0131zlar\u0131 bile \u00f6l\u00e7ebiliyor; dolay\u0131s\u0131yla \u00e7ok daha uzaktaki k\u00fcmeler hakk\u0131nda veri sunuyor. <\/span>The Astrophysical Journal<\/span><\/i>\u00a0dergisinde yay\u0131mlanacak olan bu son \u00e7al\u0131\u015fmada Gaia\u2019n\u0131n \u00f6l\u00e7\u00fcmleri 65.000 \u0131\u015f\u0131k y\u0131l\u0131 mesafe i\u00e7indeki 34 k\u00fcresel y\u0131ld\u0131z k\u00fcmesini i\u00e7erirken Hubble\u2019\u0131nkiler 130.000 \u0131\u015f\u0131k y\u0131l\u0131 mesafe i\u00e7indeki 12 k\u00fcmeyi kapsad\u0131; \u00f6l\u00e7\u00fcmler 10 y\u0131ll\u0131k bir s\u00fcrede toplanan g\u00f6r\u00fcnt\u00fclerden yola \u00e7\u0131karak ger\u00e7ekle\u015ftirildi. Ard\u0131ndan Gaia ve Hubble\u2019\u0131n \u00f6l\u00e7\u00fcmleri bir harita \u00fczerindeki tespit noktalar\u0131 misali birle\u015ftirilerek Samanyolu galaksisinin D\u00fcnya\u2019dan 1 trilyon \u0131\u015f\u0131k y\u0131l\u0131 uza\u011f\u0131ndaki bir mesafe i\u00e7inde bulunan k\u00fctle da\u011f\u0131l\u0131m\u0131 \u00f6l\u00e7\u00fcmlerine ula\u015f\u0131ld\u0131.<\/span><\/p>\n

Samanyolu’nun en eski sakinleri olan k\u00fcresel y\u0131ld\u0131z k\u00fcmeleri, evreni olu\u015fturan B\u00fcy\u00fck Patlama\u2019n\u0131n sadece birka\u00e7 y\u00fcz milyon y\u0131l sonras\u0131ndan kalma, bilinen en eski y\u0131ld\u0131zlar\u0131 i\u00e7eriyor. Bunlar\u0131n Samanyolu’nun G\u00fcne\u015f’e ve g\u00fcne\u015f sisteminin unsurlar\u0131na konakl\u0131k eden spiral diskinden de \u00f6nce olu\u015ftu\u011fu biliniyor. Hubble \u00f6l\u00e7\u00fcmlerini y\u00fcr\u00fcten Tony Sohn\u2019un belirtti\u011fi \u00fczere \u201cK\u00fcresel y\u0131ld\u0131z k\u00fcmeleri o kadar uzak mesafelere kadar yay\u0131lm\u0131\u015f durumdalar ki, g\u00f6kbilimciler a\u00e7\u0131s\u0131ndan galaksinin k\u00fctle \u00f6l\u00e7\u00fcm\u00fc i\u00e7in m\u00fckemmel bir \u00e7\u0131k\u0131\u015f noktas\u0131 sunuyorlar.\u201d \u00a0Velhas\u0131l g\u00f6r\u00fcnen o ki, kozmolojik problemlerin \u00e7\u00f6z\u00fcm\u00fcnde \u00f6nemli bir a\u00e7\u0131\u011fa d\u00f6n\u00fc\u015fm\u00fc\u015f olan Samanyolu’nun k\u00fctlesini bilmek galaksimizin kozmolojik ba\u011flamda nereye oturuyor oldu\u011funu daha iyi anlamam\u0131z\u0131 sa\u011flayacak.<\/span><\/p>\n

Kaynak<\/b>
\n<\/span>1) \u201cWhat Does the Milky Way Weigh? Hubble and Gaia Investigate\u201d, 7 Mart 2019; https:\/\/www.nasa.gov\/feature\/goddard\/2019\/what-does-the-milky-way-weigh-hubble-and-gaia-investigate.
\n<\/span>2) \u201cHubble & Gaia accurately weigh the Milky Way\u201d, Hubble Space Telescope News, 7 Mart 2019; https:\/\/spacetelescope.org\/news\/heic1905\/.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Samanyolu’nu teraziye koyup tartamay\u0131z elbette; fakat g\u00f6kbilimciler NASA’n\u0131n Hubble Uzay Teleskobu ile Avrupa Uzay Ajans\u0131’n\u0131n Gaia uydusunu kullanarak galaksimizin k\u00fctlesini en do\u011fru \u015fekilde \u00f6l\u00e7menin yolunu buldu. Son hesaplamalara g\u00f6re Samanyolu’nun a\u011f\u0131rl\u0131\u011f\u0131 yakla\u015f\u0131k 1,5 trilyon G\u00fcne\u015f k\u00fctlesi kadar (1 birim G\u00fcne\u015f k\u00fctlesi G\u00fcne\u015f\u2019in a\u011f\u0131rl\u0131\u011f\u0131na denk). Bu k\u00fctlenin \u00e7ok k\u00fc\u00e7\u00fck bir y\u00fczdesi Samanyolu’nda say\u0131lar\u0131 200 milyar\u0131 bulan […]<\/p>\n","protected":false},"author":184,"featured_media":33130,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[30,19],"tags":[4648,3787,4647,2780],"class_list":["post-33131","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-astronomi","category-bilim-gundemi","tag-gaia-uydusu","tag-hubble-uzay-teleskobu","tag-kuresel-yildiz-kumeleri","tag-samanyolu-galaksisi"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t