Sıfır yaş ana kol (ZAMS) yıldız modellerinin etkin politropik karakterizasyonu: kütle ve metalikliğin rolü

Öz

Bu çalışma, 1–40 Mʘ kütle aralığındaki Sıfır-Yaş Ana Kol (ZAMS) yıldız modelleri için etkin politropik üs γ ve buna karşılık gelen politropik indis n değerlerini sistematik olarak incelemektedir. EZ-Web kodu aracılığıyla üretilen iç yapı profilleri kullanılarak ve Radau diferansiyel denklemi çözülerek, her bir yıldız modeli tek bir etkin parametre ile karakterize edilmiştir. Sonuçlarımız, yıldız kütlesi arttıkça γ değerinin monotonik olarak azaldığını ve klasik 4/3 sınırına yaklaştığını; politropik indis n'in ise artarak daha yüksek merkezi yoğunlaşmaya sahip yapılara işaret ettiğini göstermektedir. Ayrıca, artan metal bolluğunun (Z = 0.0001–0.02), sabit bir kütlede daha yüksek n değerlerine yol açtığı saptanmıştır. Bu bulgular, klasik politropik teori ile modern sayısal yıldız evrimi arasında önemli bir köprü kurmaktadır

Anahtar Kelimeler

• Polytropik yıldız modelleri
• Radau integrasyon yöntemi
• ZAMS kütle–metaliklik ilişkisi
• yıldız iç yapısı

Effective polytropic characterization of ZAMS stellar models: The role of mass and metallicity

Öz

This study systematically investigates the effective polytropic exponent γ and the corresponding polytropic index n for Zero-Age Main-Sequence (ZAMS) stellar models within a mass range of 1–40 Mʘ . Using internal structure profiles generated via the EZ-Web code and solving the Radau differential equation, we characterize each stellar model with a single effective parameter. Our results indicate that γ decreases monotonically as stellar mass increases, approaching the classical 4/3 limit while the polytropic index n increases, signaling more centrally condensed structures. We also find that increased metallicity (Z = 0.0001–0.02) leads to higher n values at a fixed mass. These findings provide a vital bridge between classical polytropic theory and modern numerical stellar evolution.

Anahtar Kelimeler

• Polytropic stellar models
• Radau integration method
• ZAMS mass-metallicity relation
• Stellar internal structure.

Kaynakça

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