Characterize the physical conditions and origin of the eastern and southeastern components

Develop non-LTE excitation analyses to determine the physical conditions and origin of the eastern and southeastern CH3OH components around BHR71-IRS1.

Background

Only two CH3OH transitions are detected toward the eastern and southeastern components, and LTE rotation-diagram and spectral-modeling analyses cannot simultaneously reproduce the detections and nondetections. Their derived temperatures and column densities are therefore highly uncertain, and the relationship of the eastern component to IRS1 remains unresolved.

A non-LTE treatment is needed because the observed line pattern is inconsistent with LTE. Such an analysis would also help establish the physical origin of these distant features, including whether they are associated with IRS1, IRS2, or unrelated material.

References

From the archival ${12}$CO data, we find no corresponding CO emission toward E component, leaving its relationship to IRS1 unclear.

— Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) V. Tracing cavity walls and shocked knots with nonthermally desorbed CH$_3$OH in BHR71-IRS1  (2610.09500 - Yun et al., 7 Oct 2026) in Section 5.3 and Section 5.5

To determine the physical conditions in the E and SE components, further analysis that includes non-LTE excitation is required.

— Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) V. Tracing cavity walls and shocked knots with nonthermally desorbed CH$_3$OH in BHR71-IRS1  (2610.09500 - Yun et al., 7 Oct 2026) in Section 6, “Nonthermal excitation of CH$_3$OH”