Astronomlar, Samanyolu Galaksisi\u2019nin y\u0131ld\u0131z \u00fcreten diskinin yakla\u015f\u0131k 35\u201340 bin \u0131\u015f\u0131k y\u0131l\u0131 mesafede sona erdi\u011fini belirledi. Bu s\u0131n\u0131r\u0131n \u00f6tesindeki y\u0131ld\u0131zlar\u0131n ise do\u011fmad\u0131\u011f\u0131, zamanla d\u0131\u015fa g\u00f6\u00e7 etti\u011fi ortaya kondu<\/p>\n\n\n\n
Astronomlar, Samanyolu\u2019nun uzun s\u00fcredir tart\u0131\u015f\u0131lan \u201ckenar\u0131n\u0131\u201d y\u0131ld\u0131z olu\u015fumuna g\u00f6re yeniden tan\u0131mlad\u0131. Yeni ara\u015ft\u0131rma, galakside aktif y\u0131ld\u0131z olu\u015fumunun merkezden yakla\u015f\u0131k 35 ila 40 bin \u0131\u015f\u0131k y\u0131l\u0131 uzakl\u0131kta keskin bi\u00e7imde d\u00fc\u015ft\u00fc\u011f\u00fcn\u00fc g\u00f6sterdi.<\/p>\n\n\n\n
Bu mesafenin \u00f6tesinde bulunan y\u0131ld\u0131zlar\u0131n ise yerinde olu\u015fmad\u0131\u011f\u0131, galaksi i\u00e7inde zamanla d\u0131\u015fa do\u011fru g\u00f6\u00e7 etti\u011fi belirlendi.<\/p>\n\n\n\n
\u00c7al\u0131\u015fmada, 100 binden fazla dev y\u0131ld\u0131z\u0131n ya\u015f\u0131 analiz edildi. Elde edilen veriler, y\u0131ld\u0131z ya\u015flar\u0131n\u0131n galaktik merkezden uzakl\u0131\u011fa g\u00f6re \u201cU \u015feklinde\u201d bir da\u011f\u0131l\u0131m g\u00f6sterdi\u011fini ortaya koydu. Buna g\u00f6re, merkeze uzakla\u015ft\u0131k\u00e7a y\u0131ld\u0131zlar gen\u00e7le\u015fiyor; ancak yakla\u015f\u0131k 40 bin \u0131\u015f\u0131k y\u0131l\u0131ndan sonra bu e\u011filim tersine d\u00f6n\u00fcyor ve y\u0131ld\u0131zlar yeniden ya\u015flan\u0131yor. Ara\u015ft\u0131rmac\u0131lar, bu k\u0131r\u0131lma noktas\u0131n\u0131n y\u0131ld\u0131z olu\u015fumunun etkin bi\u00e7imde sona erdi\u011fi s\u0131n\u0131r\u0131 i\u015faret etti\u011fini vurgulad\u0131.<\/p>\n\n\n\n
Bilim insanlar\u0131na g\u00f6re galaksiler, \u201ci\u00e7ten d\u0131\u015fa b\u00fcy\u00fcme\u201d olarak bilinen s\u00fcre\u00e7le geli\u015fiyor. Bu modelde y\u0131ld\u0131z olu\u015fumu \u00f6nce yo\u011fun merkez b\u00f6lgelerde ba\u015fl\u0131yor ve milyarlarca y\u0131l i\u00e7inde d\u0131\u015fa do\u011fru yay\u0131l\u0131yor. Samanyolu da bu modele b\u00fcy\u00fck \u00f6l\u00e7\u00fcde uyuyor; ancak yeni bulgular, bu s\u00fcrecin belirli bir mesafede kesildi\u011fini net bi\u00e7imde ortaya koyuyor.<\/p>\n\n\n\n
Peki bu s\u0131n\u0131r\u0131n \u00f6tesinde neden h\u00e2l\u00e2 y\u0131ld\u0131zlar var? Ara\u015ft\u0131rma, bunun \u201cradyal g\u00f6\u00e7\u201d ad\u0131 verilen s\u00fcre\u00e7le a\u00e7\u0131klanabilece\u011fini g\u00f6steriyor. Y\u0131ld\u0131zlar, galaksinin sarmal kollar\u0131yla etkile\u015fime girerek zamanla daha uzak y\u00f6r\u00fcngelere ta\u015f\u0131n\u0131yor. Bu nedenle d\u0131\u015f b\u00f6lgelerdeki y\u0131ld\u0131zlar genellikle daha ya\u015fl\u0131; \u00e7\u00fcnk\u00fc bu mesafelere ula\u015fmalar\u0131 uzun zaman al\u0131yor.<\/p>\n\n\n\n
Ara\u015ft\u0131rmada ayr\u0131ca bu y\u0131ld\u0131zlar\u0131n neredeyse dairesel y\u00f6r\u00fcngelerde hareket etti\u011fi tespit edildi. Bu bulgu, y\u0131ld\u0131zlar\u0131n ba\u015fka galaksilerle \u00e7arp\u0131\u015fmalar sonucu savrulmad\u0131\u011f\u0131n\u0131, Samanyolu diski i\u00e7inde olu\u015fup zamanla yer de\u011fi\u015ftirdi\u011fini ortaya koyuyor.<\/p>\n\n\n\n
\u00c7al\u0131\u015fma, Gaia uydusunun sa\u011flad\u0131\u011f\u0131 hassas \u00f6l\u00e7\u00fcmler ile LAMOST ve APOGEE gibi spektroskopik g\u00f6zlem verilerinin birle\u015ftirilmesiyle y\u00fcr\u00fct\u00fcld\u00fc. Elde edilen sonu\u00e7lar, geli\u015fmi\u015f galaksi sim\u00fclasyonlar\u0131yla da do\u011fruland\u0131.<\/p>\n\n\n\n
Ara\u015ft\u0131rmac\u0131lar, y\u0131ld\u0131z olu\u015fumunun bu mesafede neden durdu\u011funun hen\u00fcz kesin olarak bilinmedi\u011fini belirtiyor. Olas\u0131 a\u00e7\u0131klamalar aras\u0131nda galaksinin merkez \u00e7ubu\u011funun gaz da\u011f\u0131l\u0131m\u0131n\u0131 etkilemesi veya diskin d\u0131\u015f b\u00f6lgelerinde g\u00f6r\u00fclen e\u011filmenin (warp) y\u0131ld\u0131z olu\u015fumu i\u00e7in gerekli ko\u015fullar\u0131 bozmas\u0131 yer al\u0131yor.<\/p>\n\n\n\n
Yeni g\u00f6zlem projeleri ve veri setlerinin devreye girmesiyle birlikte, Samanyolu\u2019nun yap\u0131s\u0131na dair daha ayr\u0131nt\u0131l\u0131 sonu\u00e7lara ula\u015f\u0131lmas\u0131 bekleniyor. Ara\u015ft\u0131rma, y\u0131ld\u0131z ya\u015flar\u0131n\u0131n galaktik tarih \u00e7\u00f6z\u00fcmlemesinde giderek daha kritik bir ara\u00e7 haline geldi\u011fini de ortaya koyuyor.<\/p>\n\n\n\n