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G214.5-1.8: A young, cold and quiescent giant molecular filament.

Figure 1: (Left) The column density map of G214.5-1.8 at 18.1'' resolution. (Right) The dust temperature map of G214.5-1.8 at 36.3'' resolution. The contours in both panels shows where the visual extinction is equal to 1 magnitude, i.e. 0.94 × 1021 cm-2.

Seamus Clarke

G214.5-1.8 is a satellite cloud associated with the larger Maddalena's cloud in the 3rd galactic quadrant, lying at a distance of 2.3 kpc towards the outer Galaxy. The figure shows the column density map and dust temperature map of G214.5-1.8 derived from Herschel observations. The cloud consists of a long and thin filament in the north which broadens into a wide "head" structure in the south which lies nearly perpendicular. This unique morphology and "misalignment" between the northern filament and the southern head is currently unexplained. It is approximately 0.9° long with a width that ranges from ~ 0.1° to 0.6°; this corresponds to a length of ~ 35 pc and a width ~ 4 - 24 pc. The mass of the structure is approximately 1.1 x 104 M, making it comparable in mass to the considerably more star-forming Serpens and Orion B clouds. As noted by Lee et al. (1991), G214.5-1.8 and Maddalena's cloud have very low temperatures, few protostars for their apparent size and mass, and no signs of high-mass star formation. We therefore posit that G214.5-1.8 is likely a recently formed and young GMF and is still in a quiescent phase. This is supported by our study which shows a median dust temperature of 13.8 K, colder than any known GMF in the Zucker et al. (2018) catalogue. Thus, G214.5-1.8 can help determine the initial conditions for fragmentation and star formation before feedback disrupts the cloud.