Penerapan Model Tetes Cairan pada Kerak Luar Bintang Neutron

FENI FITRISHIA, Dra. Eko Tri Sulistyani, M. Sc; Dr. Romy HS Budhi, M. Sc

2018 | Skripsi | S1 FISIKA

Telah dilakukan kajian teoritik tentang sifat kerak luar pada bintang neutron yang mendingin dengan menggunakan Model Tetes Cairan. Model ini digunakan untuk memperoleh sifat-sifat materi kerak luar bintang neutron seperti energi total sistem, persamaan keadaan (hubungan antara tekanan dan kerapatan), dan komposisi kerak luar. Bintang neutron diasumsikan telah terbentuk sejak lama dan mendingin, serta berada pada keadaan dasar. Komposisi kerak luar bintang neutron terdiri atas ion-ion positif yang tersusun dalam kisi dan elektron-elektron bebas, sehingga energi total per nukleon sistem dikontribusi oleh energi inti per nukleon, rapat energi elektron dan rapat energi kisi. Persamaan keadaan (hubungan antara tekanan dan kerapatan) menunjukkan tekanan meningkat seiring dengan bertambahnya kerapatan di lapisan kerak luar. Dengan model sederhana berdasarkan massa tetes cairan, diketahui kerak luar tersusun oleh inti-inti atom yang berada pada Z = 20-50, dengan inti 56Fe di lapisan atas, dan inti 154Cd di lapisan paling bawah kerak luar.

The properties of outer crust of cooling neutron star by using Liquid Drop Model approximation has been studied. This mass model is used to derive the properties of outer crust of neutron star matter such as total energy of system, equation of state (relationship between pressure and density), and composition of the outer crust. The properties of the outer crust are studied under the assumption that neutron star has created for long time and the matter in neutron star is in its ground state. The composition of the outer crust consists of ions Z arranged in a lattice and free electrons e, so that the total energy per nucleon of the system consists of three contributions: the mass energy of the nuclear, the energy of electrons and lattice. The equation of state (the relationship between pressure and density) shows that the pressure increases with increasing density in the outer crust layer. With a simple model based on liquid drop model, it is known that the outer crust is composed of nuclei which are at Z = 20-50, with 56Fe core in the upper layer, and 154Cd core in the lowermost layer of the outer crust.

Kata Kunci : kerak luar, bintang neutron, model tetes cairan.