An APEX search for carbon emission from NGC 1977 proplyds. Issue 2 (14th March 2022)

• Record Type: Journal Article
• Authors: Haworth, Thomas J; Kim, Jinyoung S; Qiao, Lin; Winter, Andrew J; Williams, Jonathan P; Clarke, Cathie J; Owen, James E; Facchini, Stefano; Ansdell, Megan; Kama, Mikhel; Ballabio, Giulia
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 512:Issue 2(2022)
• Page Start: 2594
• Page End: 2603
• Publication Date: 2022-03-14
• Subjects: accretion, accretion discs -- planets and satellites: formation -- protoplanetary discs -- circumstellar matter; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac656
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We used the Atacama Pathfinder Experiment ( APEX ) telescope to search for C I 1-0 (492.16 GHz) emission towards eight proplyds in NGC 1977, which is an FUV radiation environment two orders of magnitude weaker than that irradiating the Orion Nebular Cluster (ONC) proplyds. C I is expected to enable us to probe the wind launching region of externally photo-evaporating discs. Of the eight targets observed, no 3σ detections of the C I line were made despite reaching sensitivities deeper than the anticipated requirement for detection from prior APEX CI observations of nearby discs and models of external photo-evaporation of quite massive discs. By comparing both the proplyd mass loss rates and C I flux constraints with a large grid of external photo-evaporation simulations, we determine that the non-detections are in fact fully consistent with the models if the proplyd discs are very low mass. Deeper observations in C I and probes of the disc mass with other tracers (e.g. in the continuum and CO) can test this. If such a test finds higher masses, this would imply carbon depletion in the outer disc, as has been proposed for other discs with surprisingly low C I fluxes, though more massive discs would also be incompatible with models that can explain the observed mass loss rates and C I non-detections. The expected remaining lifetimes of the proplyds are estimated to be similar to those of proplyds in the ONC at 0.1 Myr. Rapid destruction of discs is therefore also a feature of common, intermediate UV environments.