Large-Scale CO Maps of the Lupus Molecular Cloud Complex

TL;DR

This study provides detailed large-scale maps of molecular gas in the Lupus clouds, revealing temperature, density, and dynamic interactions with nearby stellar associations, and compares these with existing extinction data.

Contribution

It offers the first comprehensive degree-scale maps of 13CO 2-1 and CO 4-3 transitions for Lupus I, III, and IV, highlighting cloud dynamics and external influences.

Findings

Most gas at 8-10 K temperature

Widespread dense gas indicated by CO 4-3 emission

Cloud dynamics influenced by nearby stellar activity

Abstract

Fully sampled degree-scale maps of the 13CO 2-1 and CO 4-3 transitions toward three members of the Lupus Molecular Cloud Complex - Lupus I, III, and IV - trace the column density and temperature of the molecular gas. Comparison with IR extinction maps from the c2d project requires most of the gas to have a temperature of 8-10 K. Estimates of the cloud mass from 13CO emission are roughly consistent with most previous estimates, while the line widths are higher, around 2 km/s. CO 4-3 emission is found throughout Lupus I, indicating widespread dense gas, and toward Lupus III and IV. Enhanced line widths at the NW end and along the edge of the B228 ridge in Lupus I, and a coherent velocity gradient across the ridge, are consistent with interaction between the molecular cloud and an expanding HI shell from the Upper-Scorpius subgroup of the Sco-Cen OB Association. Lupus III is dominated by the effects of two HAe/Be stars, and shows no sign of external influence. Slightly warmer gas around the core of Lupus IV and a low line width suggest heating by the Upper-Centaurus-Lupus subgroup of Sco-Cen, without the effects of an HI shell.