Back to Search Start Over

Evidence of dust grain evolution from extinction mapping in the IC 63 photodissociation region

Authors :
H. Arab
Kirill Tchernyshyov
Karl D. Gordon
Julia Roman-Duval
Benjamin F. Williams
Maarten Baes
Brandon Lawton
Dries Van De Putte
Observatoire astronomique de Strasbourg (ObAS)
Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Source :
ASTROPHYSICAL JOURNAL, The Astrophysical Journal, The Astrophysical Journal, American Astronomical Society, 2020, 888 (1), pp.22. ⟨10.3847/1538-4357/ab557f⟩
Publication Year :
2020

Abstract

Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between H II regions and molecular clouds. The physical conditions within these regions show variations on very short spatial scales, and therefore PDRs constitute ideal laboratories for investigating the properties and evolution of dust grains. We have mapped IC 63 at high resolution from the UV to the NIR (275 nm to 1.6 $\mu$m), using the Hubble Space Telescope WFC3. Using a Bayesian SED fitting tool, we simultaneously derive a set of stellar ($T_\text{eff}$, $\log(g)$, distance) and extinction ($A_V$, $R_V$) parameters for 520 background stars. We present maps of $A_V$ and $R_V$ with a resolution of 25 arcsec based on these results. The extinction properties vary across the PDR, with values for $A_V$ between 0.5 and 1.4 mag, and a decreasing trend in $R_V$, going from 3.7 at the front of the nebula to values as low as 2.5 further in. This provides evidence for evolution of the dust optical properties. We fit two modified blackbodies to the MIR and FIR SED, obtained by combining the $A_V$ map with data from Spitzer and Herschel. We derive effective temperatures (30 K and 227 K) and the ratio of opacities at 160 $\mu$m to V band $\kappa_{160} / \kappa_V$ ($7.0 \times 10^{-4}$ and $2.9 \times 10^{-9}$) for the two dust populations. Similar fits to individual pixels show spatial variations of $\kappa_{160} / \kappa_{V}$. The analysis of our HST data, combined with these Spitzer and Herschel data, provides the first panchromatic view of dust within a PDR.<br />Comment: 28 pages, 20 figures, accepted for publication in The Astrophysical Journal

Details

Language :
English
ISSN :
15384357 and 0004637X
Database :
OpenAIRE
Journal :
ASTROPHYSICAL JOURNAL, The Astrophysical Journal, The Astrophysical Journal, American Astronomical Society, 2020, 888 (1), pp.22. ⟨10.3847/1538-4357/ab557f⟩
Accession number :
edsair.doi.dedup.....dc521335c68688dbba4da51560442e02