English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We have mapped the NGC 2023 reflection nebula in [CII] and CO(11--10) withthe heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in13CO(3--2), CO(3--2), CO(4--3), CO(6--5), and CO(7--6) with APEX in Chile. Weuse these data to probe the morphology, kinematics, and physical conditions ofthe C II region, which is ionized by FUV radiation from the B2 star HD37903.The [CII] emission traces an ellipsoidal shell-like region at a position angleof ~ -50 deg, and is surrounded by a hot molecular shell. In the southeast,where the C II region expands into a dense, clumpy molecular cloud ridge, wesee narrow and strong line emission from high-J CO lines, which comes from athin, hot molecular shell surrounding the [CII] emission. The [CII] lines arebroader and show photo evaporating gas flowing into the C II region. Based onthe strength of the [13CII] F=2--1 line, the [CII] line appears to be somewhatoptically thick over most of the nebula with an optical depth of a few. Wemodel the physical conditions of the surrounding molecular cloud and the PDRemission using both RADEX and simple PDR models. The temperature of the COemitting PDR shell is ~ 90 -- 120 K, with densities of 10^5 -- 10^6 cm^-3, asdeduced from RADEX modeling. Our PDR modeling indicates that the PDR layerwhere [CII] emission dominates has somewhat lower densities, 10^4 to a fewtimes 10^5 cm^-3

High Spectral and Spatial Resolution Observations of the PDR Emission in the NGC2023 Reflection Nebula with SOFIA and APEX