Interstellar extinction in Orion: variation of the strength of the ultraviolet bump across the complex

Beitia-Antero, Leire; Castro, Ana Inés Gómez de

doi:10.1093/mnras/stx881

Cited by 11 publications

(4 citation statements)

References 30 publications

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“…However, local variations of the dust-to-gas ratio are to be expected (Padoan et al 2006;Hopkins 2014), especially when the dust particles are charged (Lazarian & Yan 2002;Lee et al 2017), and they are actually found in the diffuse medium and even inside a cloud (Siebenmorgen et al 2017;Chen et al 2015;Reach et al 2015). There were some early attempts to determine the scale of the fluctuations from extinction measurements (Thoraval et al 1997(Thoraval et al , 1999 and variations of the dust size distribution have been found in MCs (Flagey et al 2009;Köhler et al 2015;Gómez de Castro et al 2015;Beitia-Antero & Gómez de Castro 2017). However, most of the studies are focused on the cool interiors of MCs since the main interest is to determine the possible influence of this phenomenon over the star formation processes.…”

Section: Discussionmentioning

confidence: 99%

Formation of Dust Filaments in the Diffuse Envelopes of Molecular Clouds

Beitia-Antero

Castro

Vallejo

2021

ApJ

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The path to understanding star formation processes begins with the study of the formation of molecular clouds. The outskirts of these clouds are characterized by low column densities that allow the penetration of ultraviolet radiation, resulting in a non-negligible ionization fraction and the charging of the small dust grains that are mixed with the gas; this diffuse phase is then coupled to the ambient magnetic field. Despite the general assumption that dust and gas are tightly correlated, several observational and theoretical studies have reported variations in the dust-to-gas ratio toward diffuse and cold clouds. In this work, we present the implementation of a new charged particles module for analyzing the dust dynamics in molecular cloud envelopes. We study the evolution of a single population of small charged grains (0.05 µm) in the turbulent, magnetized molecular cloud envelope using this module. We show that variations in the dust-to-gas ratio arise due to the coupling of the grains with the magnetic field, forming elongated dust structures decoupled from the gas. This emphasizes the importance of considering the dynamics of charged dust when simulating the different phases of the interstellar medium, especially for star formation studies.

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Section: Discussionmentioning

confidence: 99%

Formation of Dust Filaments in the Diffuse Envelopes of Molecular Clouds

Beitia-Antero

Castro

Vallejo

2021

ApJ

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“…The main feature is the so-called UV bump at 2175 Å that is caused by very small carbonaceous particles; polycyclic aromatic hydrocarbon (PAH) molecules have been put forward as the main carriers of the bump (Weingartner & Draine 2001b) although there may be a substantial contribution of small graphite grains (Stecher & Donn 1965) or even multi-shell fullerenes, usually called buckyonions (Iglesias-Groth 2004). Variations in the strength of the UV bump have been observed in our Galaxy (Witt et al 1984;Gómez de Castro et al 2015;Beitia-Antero & Gómez de Castro 2017) but also towards other nearby galaxies (Prevot et al 1984;Decleir et al 2019). The other characteristic feature of the UV extinction curve is the steep slope at far ultraviolet (FUV) wavelengths.…”

Section: Introductionmentioning

confidence: 96%

Dust growth in molecular cloud envelopes: a numerical approach

Beitia-Antero,

de Castro

2021

Preprint

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Variations in the grain size distribution are to be expected in the interstellar medium (ISM) due to grain growth and destruction. In this work, we present a dust collision model to be implemented inside a magnetohydrodynamical (MHD) code that takes into account grain growth and shattering of charged dust grains of a given composition (silicate or graphite). We integrate this model in the MHD code Athena, and builds on a previous implementation of the dynamics of charged dust grains in the same code. To demonstrate the performance of this coagulation model, we study the variations in the grain size distribution of a single-sized population of dust with radius 0.05 µm inside several dust filaments formed during a 2D MHD simulation. We also consider a realistic dust distribution with sizes ranging from 50 Å to 0.25 µm and analyze both the variations in the size distribution for graphite and silicates, as well as of the far ultraviolet extinction curve. From the obtained results, we conclude that the methodology here presented, based on the MHD evolution of the equation of motion for a charged particle, is optimal for studying the coagulation of charged dust grains in a diffuse regime such as a molecular cloud envelope. Observationally, these variations in the dust size distribution are translated into variations in the far ultraviolet extinction curve, and they are mainly caused by small graphite dust grains.

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“…The main feature is the so-called UV bump at 2175Å that is caused by very small carbonaceous particles; polycyclic aromatic hydrocarbon (PAH) molecules have been put forward as the main carriers of the bump (Weingartner & Draine 2001b) although there may be a substantial contribution of small graphite grains (Stecher & Donn 1965) or even multi-shell fullerenes, usually called buckyonions (Iglesias-Groth 2004). Variations in the strength of the UV bump have been observed in our Galaxy (Witt et al 1984;Gómez de Castro et al 2015;Beitia-Antero & Gómez de Castro 2017) but also towards other nearby galaxies (Prevot et al 1984;Decleir et al 2019). The other characteristic feature of the UV extinction curve is the steep slope at far ultraviolet (FUV) wavelengths.…”

Section: Introductionmentioning

confidence: 96%

Dust Growth in Molecular Cloud Envelopes: A Numerical Approach

Beitia-Antero

Castro

2021

ApJ

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Variations in the grain size distribution are to be expected in the interstellar medium (ISM) due to grain growth and destruction. In this work, we present a dust collision model to be implemented inside a magnetohydrodynamical (MHD) code that takes into account grain growth and shattering of charged dust grains of a given composition (silicate or graphite). We integrate this model in the MHD code Athena, and builds on a previous implementation of the dynamics of charged dust grains in the same code. To demonstrate the performance of this coagulation model, we study the variations in the grain size distribution of a single-sized population of dust with radius 0.05 µm inside several dust filaments formed during a 2D MHD simulation. We also consider a realistic dust distribution with sizes ranging from 50Å to 0.25 µm and analyze both the variations in the size distribution for graphite and silicates, as well as of the far ultraviolet extinction curve. From the obtained results, we conclude that the methodology here presented, based on the MHD evolution of the equation of motion for a charged particle, is optimal for studying the coagulation of charged dust grains in a diffuse regime such as a molecular cloud envelope. Observationally, these variations in the dust size distribution are translated into variations in the far ultraviolet extinction curve, and they are mainly caused by small graphite dust grains.

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Interstellar extinction in Orion: variation of the strength of the ultraviolet bump across the complex

Cited by 11 publications

References 30 publications

Formation of Dust Filaments in the Diffuse Envelopes of Molecular Clouds

Formation of Dust Filaments in the Diffuse Envelopes of Molecular Clouds

Dust growth in molecular cloud envelopes: a numerical approach

Dust Growth in Molecular Cloud Envelopes: A Numerical Approach

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