Comparing Complex Chemistry in Neighboring Hot Cores: NOEMA Studies of W3(H₂O) and W3(OH)

Abstract

Presented here are NOEMA interferometric observations of the neighboring hot cores W3(H2O) and W3(OH). The presence of two star-forming cores at different evolutionary stages within the same parent cloud presents a unique opportunity to study how the physics of the source and its evolutionary stage impact the chemistry. Through spectral analysis and imaging, we identify over 20 molecules in these cores. Most notably, we have detected HDO and CH3CH2CN in W3(OH), which were previously not detected in this core. We have imaged the molecular emission, revealing new structural features within these sources. W3(OH) shows absorption in a “dusty cocoon” surrounded by molecular emission. These observations also reveal extended emission that is potentially indicative of a low-velocity shock. From the information obtained herein, we have constructed column density and temperature maps for methanol and compared this information to the molecular images. By comparing the spatial distribution of molecules that may be destroyed at later stages of star formation, this work demonstrates the impact of physical environment on chemistry in star-forming regions at different evolutionary stages.

Mapping Physical Conditions in Neighboring Hot Cores: NOEMA Studies of W3(H2O) and W3(OH)

“…While specific details on the observations and data reduction process are described in Thompson et al (2023), an overview of the observations is described here. The two hot cores W3(H 2 O) and W3(OH) were observed in 2021 using the IRAM/NOEMA interferometer 4 in the C and D configurations with frequency coverage from 127.823 to 135.311 GHz and 143.116 to 150.666 GHz across the two receiver sidebands.…”

“…The data sets were then reduced using the GILDAS packages CLIC and MAPPING, 5 resulting in a synthesized beam of ∼1 87 × 1 34 (PA = −9°.3) in the lower sideband and ∼1 69 × 1 22 (PA = −7°.9) in the upper sideband. Figure 1 in Thompson et al 2023 shows the imaged continuum at 132 GHz. At this frequency, the continuum emission from W3(OH) consists mostly of free-free emission, while that of W3(H 2 O) is due to dust (Wilner et al 1995;Wyrowski et al 1997Wyrowski et al , 1999Stecklum et al 2002).…”

“…The neighboring hot cores W3(H 2 O) and W3(OH) provide a unique environment to study how the molecular complexity can differ across different sources. The two cores are at different stages of stellar evolution, with W3(OH) being an ultracompact H II region (Helmich & van Dischoeck 1997;Rivera-Ingraham et al 2013;Qin et al 2015;Widicus Weaver et al 2017;Thompson et al 2023). Given that they formed from the same parent cloud, these two cores are well-suited for studying how prebiotic chemistry evolves during the star formation process.…”

“…W3(H 2 O) and W3(OH) are so named due to the presence of H 2 O and OH masers, respectively, and are at a distance of ∼2 kpc from Earth with a v lsr of −47 km s −1 (Wynn- Williams et al 1972;Wyrowski et al 1997;Wilner et al 1999;Rivera-Ingraham et al 2013). Thompson et al (2023) recently presented results from millimeter-wave interferometric observations of these two cores. Building on this work, herein we present further chemical analysis of the six molecules that were quantitatively analyzed in Thompson et al (2023).…”

“…Thompson et al (2023) recently presented results from millimeter-wave interferometric observations of these two cores. Building on this work, herein we present further chemical analysis of the six molecules that were quantitatively analyzed in Thompson et al (2023). This current study includes detailed parameter maps for these molecules in the two cores based on rotational temperature, column density, and velocity shift relative to v lsr .…”