Radiative transfer modeling of the low-mass proto-binary system, IRAS 4A1 and 4A2.

Area of Science:

• Astronomy and Astrophysics
• Astrochemistry
• Star Formation

Background:

• NGC 1333 IRAS4A is a low-mass, sun-like proto-binary system with distinct components A1 and A2.
• Previous studies have noted diverse physical and chemical properties between A1 and A2.

Purpose of the Study:

• To understand the kinematical and chemical differences between A1 and A2.
• To classify dust emission and absorption properties in the system.
• To explain observed spectral signatures of methanol (CH3OH) and formaldehyde (H2CO).

Main Methods:

• Modeling the hot corino using the RATRAN radiative transfer code.
• Utilizing high-resolution interferometric observations from ALMA and VLA.
• Expanding models from millimeter to centimeter wavelengths.

Main Results:

• Dust opacity is identified as the primary cause for differing spectral profiles between A1 and A2.
• A1 exhibits optically thick dust continuum emission, leading to absorption lines.
• A2 shows optically thin dust continuum emission, resulting in emission profiles and an inverse P-Cygni profile indicating infall.

Conclusions:

• The opacity effect significantly influences observed spectral signatures in proto-binary systems.
• Reduced opacity at centimeter wavelengths leads to emission profiles.
• The model successfully reproduced population inversion causing methanol maser emission.