Tracking the dynamical, chemical and spectral evolution of molecular cores with PrestaLine: Gorynych

TL;DR

PrestaLine: Gorynych introduces a post-processing pipeline that unites three components—Kamelung for 1D collapse dynamics, Presta for time-dependent chemistry, and Uran(IA) for radiative transfer—to model the dynamical, chemical, and spectral evolution of collapsing molecular cores from the prestellar phase through FHSC formation to protostellar accretion. By comparing a low-mass core (5 $M_\odot$) with a high-mass core (50 $M_\odot$), the study finds remarkably similar dynamical evolution with differences mainly in spatial scaling, while chemistry shows sharp transitions at the FHSC stage for key species like CO, H$_2$O, and HCO$^+$. The framework reveals distinct kinematic signatures in synthetic maps of $^{13}$CO(2--1), HCO$^+$(3--2), and H$_2$O(110--101), including infall-driven depletion and extended emission in higher-mass cores, highlighting how initial conditions imprint on line data. Overall, Gorynych provides a practical, modular platform to connect theoretical collapse models with observations, enabling diagnostics of core evolution and initial conditions from molecular line observations.

Abstract

We present PrestaLine: Gorynych, a comprehensive numerical tool designed to model the dynamical, chemical, and spectral evolution of collapsing molecular cores from the prestellar phase to protostellar accretion. The code integrates three key components: (1) Kamelung, a 1D hydrodynamics module simulating gravitational collapse up to first hydrostatic core (FHSC) formation followed by an accretion of envelope onto a young star; (2) Presta, a chemical evolution module post-processing density and temperature profiles to compute time-dependent molecular abundances; and (3) Uran(IA), a radiative transfer module generating synthetic molecular line spectra. We apply Gorynych to compare low-mass (5 Msun) and high-mass (50 Msun) cores, finding that their dynamical evolution is remarkably similar, with differences primarily in spatial scaling. Chemical evolution reveals sharp abundance changes during the FHSC transition, particularly for CO, H2O, and HCO+, though pre-collapse chemical initialization has minimal impact on most species. Spectral maps of 13CO(2-1), HCO+(3-2), and H2O(110--101) lines show distinct kinematic signatures of infall and depletion, with high-mass cores exhibiting spatially extended emission. Our results highlight Gorynych's utility to couple theoretical collapse models and observations, providing a framework to diagnose core evolution and initial conditions from molecular line data.

Figures (5)

• Figure 1: Various cooling functions and the adopted approximation.
• Figure 2: Evolution of density, velocity and temperature distributions for the low mass (left) and high mass (right) cores. Blue and red lines in the left top panel represent the power laws $n\propto r^{-2}$ and $n\propto r^{-1.5}$, correspondingly.
• Figure 3: Column densities and total masses of selected species as a function of time for the HM and LM models.
• Figure 4: Radial abundance profiles of the selected species at three time moments, representing the prestellar phase, the formation of the FHSC, and the protostellar phase.
• Figure 5: Spectra and integral intensity distributions for $^{13}$CO(2--1) (top), HCO$^+$(3--2) (middle), and H$_2$O(110--101) (bottom) emission corresponding to three stages of evolution: the prestellar core (globlule) ($n_0($H$_2)=2 \times 10^5$ cm$^{-3}$, $t\sim 40$ thousand years for LM, $t\sim 44$ thousand years for HM), the FHSC (core) ($n_0($H$_2)=10^{14}$ cm$^{-3}$, $t\sim 45$ thousand years for LM, and $t\sim 49$ thousand years for HM), and the protostellar object (protostar) ($t\sim700$ thousand years)