The elements present in the core of a star or planet can be determined through a process called spectroscopy. This involves analyzing the light emitted by the object and identifying the specific wavelengths of light that correspond to different elements. By comparing these wavelengths to known spectra of elements, scientists can determine which elements are present in the core.
The temperature of the core can be estimated using mathematical models and observations of the object's surface temperature. By studying the object's luminosity, size, and mass, scientists can use equations to estimate the temperature at the core. Additionally, studying the nuclear reactions taking place in the core can also provide insight into its temperature.
In addition to spectroscopy, scientists also use techniques such as seismology and computer simulations to study the composition of a star or planet's core. Seismology involves studying the seismic waves that travel through an object, providing information about its internal structure. Computer simulations allow scientists to model the behavior of different materials under extreme conditions, giving insight into the composition of the core.
The density of a core can be calculated by combining information about its mass and volume. The mass can be estimated through observations of the object's gravitational pull, while the volume can be estimated through measurements of its size. By dividing the mass by the volume, scientists can determine the average density of the core.
While scientists can make educated guesses about the composition of a star or planet's core based on various observations and models, it is challenging to determine the exact composition. This is because the core is typically inaccessible and often subject to extreme conditions, making it difficult to obtain accurate measurements. However, advancements in technology and scientific methods continue to improve our understanding of the composition of these objects' cores.