The power of adaptive optics: a close look at a molecular cloud in NGC 2023

• Published in: Monthly notices of the Royal Astronomical Society 1997-01, Vol.284 (2), p.395-400
• Main Authors: Rouan, D., Field, D., Lemaire, J.-L., Lai, O., des Forêts, G.Pineau, Falgarone, E., Deltorn, J.-M.
• Format: Article
• Language: English
• Subjects: infrared: ISM: lines and bands; ISM: clouds; ISM: individual: NGC 2023; reflection nebulae; stars: formation
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/284.2.395

Observations of the reflection nebula NGC 2023, a region of recent star formation, have revealed small-scale structure in the associated molecular cloud, close to the exciting star, at a spatial resolution of 50 to 75 au. These results have been obtained using adaptive optics on the ESO 3.6-m telescope at La Silla, observing in the H2 υ= 1−0 S(1) near-IR emission line at 2.121 μm. Our observations are among the first to involve the use of adaptive optics combined with spectral line resolution. The observed fragment of molecular cloud, a remnant of the material from which the B-star in NGC2023 formed, contains a number of features whose H2 emission brightness contrast to the surrounding material is an order of magnitude. These structures are interpreted in terms of clumps of gas exhibiting a density contrast of at least an order of magnitude. We discuss the possibility that turbulence plays a role in the creation of the observed structures.