Değişen Yıldız Fotometrisinde STEREO Uydu Verilerinin Güvenilirliği

Son on yılda uzay teknolojisinin gelişmesiyle birlikte uzaya yollanan yüksek çözünürlüklü ve kesintisiz gözlem yapabilen teleskoplar sayesinde hem yakın çevremizdeki hem de Evren’in derinliklerindeki gökcisimleri daha ayrıntılı olarak incelenmeye başlanmıştır. Bu çalışmalar arasında galaktik ve galaksi dışı gözlemler, Güneş’in atmosferinin incelenmesi ve ötegezegen araştırmaları başı çekmektedir. Bu araştırmalar için kullanılabilen önemli teleskoplardan ikisi STEREO ve TESS’dir. STEREO’nun asıl görevi Güneş’teki madde atımlarını takip etmek ve TESS’in görevi ise yeni ötegezenler keşfetmektir. Ancak bunların yanı sıra, bu teleskoplar arka planda bulunan milyonlarca yıldızın ışık değişimlerini gözleme özelliğine de sahiptir. Bu sayede yıldız astrofiziğinde oldukça önemli gelişmeler yaşanmaktadır. Bununla birlikte, çok sayıda yıldızın aynı anda gözlenmesiyle büyük veri kümeleri elde edilmeye başlanmış ve bunun sonucu olarak da bilgisayar kodlarının kullanıldığı otomatik veri işleme süreçleri ortaya çıkmıştır. Ancak bu süreç birçok sorunu da beraberinde getirmektedir. Çok sayıda ve çeşitli türdeki yıldızların analiz edilmeye çalışılması veri indirgeme ve analiz kodlarının aynı hassasiyetle çalışmasına izin vermemekte ve insan kaynaklı hataların da işin içine girmesine neden olmaktadır. Bu duruma uzay aracından kaynaklanan sorunlar da eklendiğinde elde edilen veride ve analiz sonuçlarında ciddi problemler ortaya çıkabilmektedir. Bu bağlamda, STEREO uydusundan elde edilen 41 tane Be türü yıldızın ışık eğrileri analiz edilmiş ve verilerde yıldızlardan kaynaklanmayan bir problem ile karşılaşılmıştır. Daha net bilgiler elde edebilmek için bu 41 yıldızdan TESS ile gözlenmiş olanlar belirlenmiş ve iki uydudan alınan ışık eğrileri karşılaştırılmıştır. Elde edilen sonuçlara dayanarak STEREO verilerindeki problem irdelenmiştir.

Anahtar Kelimeler:

STEREO uydusu, TESS uydusu, Fotometri, Veri analizi, Astrosismoloji

Reliability of STEREO Satellite Data in Variable Star Photometry

Thanks to space telescopes with high resolution and uninterrupted observations, celestial objects in our immediate surroundings and in the depths of the Universe have been studied in more detail for last ten years. Among these studies, galactic and extragalactic observations, solar atmosphere and exoplanet research are the leading ones. Two of the important telescopes available for these studies are STEREO and TESS. The main task of the STEREO is to follow coronal mass ejections while TESS's mission is to discover new exoplanets. These telescopes also have the ability to observe the light variations of millions of stars in the background. Therefore, significant advances have been made in stellar astrophysics. Yet, simultaneous observations of many stars cause large datasets to be obtained and consequently, automatic data processing processes using computer codes arise. This process brings several problems with it. Attempting to analyze many and various types of stars does not allow data reduction and analysis codes to work with the same precision and also causes human-induced errors to get involved. When spacecraft-related problems are added to this situation, serious problems may arise in the data obtained and in the results of the analysis. In this context, STEREO data of 41 Be type stars are analyzed and a problem not caused by the stars is encountered in the data. Afterwards, the ones observed with TESS are determined and the light curves taken from the two satellites are compared. Based on the results obtained, the problem in the STEREO data is scrutinized

Keywords:

STEREO satellite, TESS satellite, Photometry, Data analysis, Asteroseismology,

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