Browsing by Subject "Synthetic Observations"

We investigated the connection between the 3D physical properties of stellar clusters and their measured counterparts from their 2D observed images; primarily focusing on the relationship be- tween the 3D half-mass radius (Rh3D) and the effective radius (Rheff) (also known as the 2D half-light radius) of stellar clusters. We generated an ensemble of 3D models of stellar clusters using the McLuster code. This ensemble is made up of subgroups consisting of different stellar counts, half-mass radius, concentration, maximum mass of the initial mass function, and degree of mass segregation. Each subgroup covered a broad range of their respective property in order to provide a comprehensive overview of the Rh3D to Rheff relationship as a function of these variables. Then, utilizing myosotis, we created synthetic observations of these models and investigated how the Rh3D of the cluster could be inferred from the measured Rheff of the synthetic photometric map. Our analysis reveals that for systems where all stars are of equal mass, independent of their size, the half-mass radius is equal to Rh3D ≈ 1/α Rheff where α ∼ 0.76. We show that the value of α can be inferred by a geometric relationship. We also find that this relationship holds for systems with varying values of concentration. For unsegregated systems of unequal stellar masses, we observe that the value of α oscillates around 0.76, with the amplitude of the oscillations increasing as the maximum mass of the system increases. As Rh3D by construction does not change, the only parameter to cause this variation in α is the Rheff . When we looked at mass segregated systems, we found that the value of Rheff (and similarly α) decreases generally monotonically as a function of the degree of the segregation. The presence of stars of unequal mass is the dominant factor that determines the measurements of Rheff , beyond the geometric effects of projection. The prevalence of this factor is attributed to the non-linear relationship between mass and luminosity that results in a few tens of massive stars greatly influencing the overall luminosity of the cluster, and therefore, its effective radius.