Multi-scale analysis of the Monoceros OB 1 star-forming region I. The dense core population

Context. Current theories and models attempt to explain star formation globally, from core scales to giant molecular cloud scales. A multi-scale observational characterisation of an entire molecular complex is necessary to constrain them. We investigate star formation in G202.3+2.5, a∼10 × 3 pc sub-region of the Monoceros OB1 cloud with a complex morphology that harbours interconnected filamentary structures. Aims. We aim to connect the evolution of cores and filaments in G202.3+2.5 with the global evolution of the cloud and to identify the engines of the cloud dynamics. Methods. In this first paper, the star formation activity is evaluated by surveying the distributions of dense cores and protostars and their evolutionary state, as characterised using both infrared observations from the Herschel and WISE telescopes and molecular line observations with the IRAM 30 m telescope. Results. We find ongoing star formation in the whole cloud, with a local peak in star formation activity around the centre of G202.3+2.5, where a chain of massive cores (10−50 M) forms a massive ridge (>150 M). All evolutionary stages from starless cores to Class II protostars are found in G202.3+2.5, including a possibly starless and massive (52 M) core, which presents a high column density (8 × 1022 cm−2). Conclusions. All the core-scale observables we examined point to an enhanced star formation activity that is centred on the junction between the three main branches of the ramified structure of G202.3+2.5. This suggests that the increased star formation activity results from the convergence of these branches. To further investigate the origin of this enhancement, it is now necessary to extend the analysis to larger scales in order to examine the relationship between cores, filaments, and their environment. We address these points through the analysis of the dynamics of G202.3+2.5 in a joint paper

A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk

Differential electron emission from polycyclic aromatic hydrocarbon molecules under fast ion impact

Interaction between polycyclic aromatic hydrocarbon (PAH) molecule and energetic ion is a subject of interest in different areas of modern physics. Here, we present measurements of energy and angular distributions of absolute double differential electron emission cross section for coronene (C24H12) and fluorene (C13H10) molecules under fast bare oxygen ion impact. For coronene, the angular distributions of the low energy electrons are quite different from that of simpler targets like Ne or CH4, which is not the case for fluorene. The behaviour of the higher electron energy distributions for both the targets are similar to that for simple targets. In case of coronene, a clear signature of plasmon resonance is observed in the analysis of forward-backward angular asymmetry of low energy electron emission. For fluorene, such signature is not identified probably due to lower oscillator strength of plasmon compared to the coronene. The theoretical calculation based on the first-order Born approximation with correct boundary conditions (CB1), in general, reproduced the experimental observations qualitatively, for both the molecules, except in the low energy region for coronene, which again indicates the role of collective excitation. Single differential and total cross sections are also deduced. An overall comparative study is presented

Explicating corporate heritage, corporate heritage brands and organisational heritage

Recently, considerable academic and management interest has focussed on corporate heritage and, in particular, on the corporate heritage brand notion. This article provides a thorough overview of the field and includes latest developments in the territory including the formal introduction of the organisational heritage concept. Drawing on the extant literature, the article explores five themes relating the broad corporate heritage field: contexts, foundations, fundamentals, advances and empirical insights. This overview also examines key constructs within the domain including corporate heritage brands, corporate heritage identity and organisational heritage. Both theoretical and managerial aspects of the field are addressed. Reference is made to recent empirical contributions and to prominent case study research from Great Britain and China, namely Shepherd Neame (Britain’s oldest brewery with an official founding date of 1698) and Tong Ren Tang (the renowned traditional Chinese medicine corporate brand dating back to 1669)

Dust and molecular formation in supernovae

Up to 1987, supernovae (SNe) and supernova remnants (SNRs) had been thought to be hostile environments for molecules and dust grains. Fast-moving electrons in young SNe can destroy molecules, and strong X-ray radiation and shocks can destroy molecules and dust grains in SNRs. That concept was broken by detection of CO, SiO, and dust thermal emission in Supernova 1987A. Since 1987, the number of studies which have found molecules and dust in SNe and SNRs is slowly increasing. Detecting molecules can be a powerful tool to investigate dynamical motion, density, temperature, and chemistry. Dust formation can affect the thermal balance in SNe and SNRs, and radiation from dust grains can be about as high as 50 % of the cooling of the expanding ejecta. Isotopologues are molecules that differ only in respect to the isotopes of some of the constituent elements. Isotopologues found in SNe and SNR probe isotopes that can be compared with predictions of explosive nucleosynthesis. Because SNe are a major source of heavy elements, if a significant fraction of refractory elements condense into dust grains, SNe can be an important source of the dust in the interstellar medium of galaxies. In this review, the discovery of molecules and dust in SNe and SNRs and their implications are summarised