arXiv subjects

P. Dell'ova

Publications and source records attributed to P. Dell'ova.

2 recordsLinked to original sources

arXiv2026

JWST observations of photodissociation regions. IV. Carbonaceous emission band sub-components in NGC 7023 have distinct spatial distributions

We analyze JWST spectroscopy of the northwest filament of NGC7023, where the relatively soft radiation field results in a photodissociation region with an extended atomic hydrogen region, and strongly pronounced variations of the carbonaceous emission band profiles. We focus on the 16.4 and 17.4 um bands and their relation to the main bands at 3.3, 3.4, 5.2, 5.7, 6.2, 7.7, 8.6, 11.3, and 12.7 um, and aim to identify which bands and sub-features originate from co-spatial emission carriers. We apply a PAHFIT spectral decomposition to measure the emission bands and their individual sub-components, and produce maps that spatially resolve the main dissociation front (DF1). Nearly all emission maps peak at DF1, while the relative intensity in the atomic hydrogen region (ATM) varies strongly. We classify the features into spatial distribution types based on the intensity ratio in ATM relative to DF1. Most bands are of type I (low ATM/DF1; 3.3, 3.4, 5.2, 5.7, 11.3 um) or II (medium ATM/DF1; 16.2, 7.7, 8.6, 12.7, 16.4 um), while only few are of type III (high ATM/DF1; 11.0, 17.4 um). A breakdown of the 5.7, 7.7, 11.3 and 12.7 um bands into blue and red sub-components reveals that contributions on the blue side are of type III, while those on the red side are of type I or II. These strongly differing spatial distributions reveal that at least two different populations contribute to the 16-18 um range, and that these populations are also connected to the profiles of the 5.7, 7.7, 11.3, and 12.7 um bands. The maps further indicate a continued evolution of these profiles toward the central cavity of NGC7023, where fullerene emission (C60) was previously detected. We speculate that the population of emission carriers could be in an intermediate photochemical evolution stage that precedes fullerene formation.

astro-ph.GA↗

arXiv2025

JWST Observations of Photo-dissociation Regions. II. Aliphatic/Aromatic Carbonaceous Dust, Ices, and Gas Phase Spectral Line Inventory

This paper provides an overview of the spectroscopic data obtained by the JWST Guaranteed Time Observations (GTO) program 1192, "The Physics and Chemistry of PDR Fronts", including an inventory of the spatially resolved dust, gas, and molecular content in the Horsehead nebula and the NW filament of NGC~7023. We demonstrate the unique capability of this high spatial resolution data set to elucidate the evolution of gas and dust at the interface between stars and their natal clouds at the scale at which the physics and chemistry occur. The Disassociation Regions (PDRs) in the Horsehead nebula and the North West (NW) filament of NGC 7023 were mapped with a spectral resolution 1000-3000 and a spatial resolution of ~2e-4 pc between 0.97-28um. Spectra extracted from template regions yield a large number of atomic, ionized, and molecular lines. Full line lists and extracted spectra for all 10 regions are provided through CDS. Absorption from H$_2$O, CO$_2$, and CO ices are identified in 3 regions in NGC 7023. In this overview, we have focused on the spectral region between 3 and 5 um which is dominated by emission from aromatic and aliphatic carbon bonds to illustrate the power of the data set. We confirm the entrainment of aromatic carbonaceous species in the photo-evaporative flow from the PDR surface into the H\,{\sc{ii}} region in the Horsehead. No aliphatic emission is present in the outflow, indicating the complete removal of aliphatic bonds when exposed to strong UV fields. There is a clear detection of deuterium substitution in the carbon bonds. Aliphatic D-substitution is more efficient relative to aromatic D-substitution, ranging from N$_{D}$/N$_{H}$ ~ 0.1-0.3 for aliphatics compared to ~0.03 for the aromatics.

astro-ph.GA↗