Infrared Spectroscopic Survey of the Quiescent Medium of Nearby Clouds: II. Ice Formation and Grain Growth in Perseus and Serpens

Abstract

The properties of dust change during the transition from diffuse to dense clouds as a result of ice formation and dust coagulation, but much is still unclear about this transformation. We present 2-20 micron spectra of 49 field stars behind the Perseus and Serpens Molecular Clouds and establish relationships between the near-infrared continuum extinction (AK) and the depths of the 9.7 micron silicate (tau97) and 3.0 micron H2O ice (tau30) absorption bands. The tau97/AK ratio varies from large, diffuse interstellar medium-like values (~0.55), to much lower ratios (~0.26). Above extinctions of AK~1.2 (AV~10; Perseus, Lupus, dense cores) and ~2.0 (AV~17; Serpens), the tau97/AK ratio is lowest. The tau97/AK reduction from diffuse to dense clouds is consistent with a moderate degree of grain growth (sizes up to ~0.5 micron), increasing the near-infrared color excess (and thus AK), but not affecting ice and silicate band profiles. This grain growth process seems to be related to the ice column densities and dense core formation thresholds, highlighting the importance of density. After correction for Serpens foreground extinction, the H2O ice formation threshold is in the range of AK=0.31-0.40 (AV=2.6-3.4) for all clouds, and thus grain growth takes place after the ices are formed. Finally, abundant CH3OH ice (~21% relative to H2O) is reported for 2MASSJ18285266+0028242 (Serpens), a factor of >4 larger than for the other targets.

arXiv comment29 pages+17 pages appendix. Published in The Astrophysical Journal, 930, 2, 2022

References in corpus (31)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Observations of the Icy Universe
• A Method of Correcting Near-Infrared Spectra for Telluric Absorption
• The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 microns Using GLIMPSE Data
• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• From Molecular Cores to Planet-forming Disks: A SIRTF Legacy Program
• Water, O2 and Ice in Molecular Clouds
• The c2d Spitzer Spectroscopic Survey of Ices Around Low-Mass Young Stellar Objects: I. H2O and the 5-8 um Bands
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus
• A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2 Edition
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. III. Perseus Observed with IRAC
• The Ubiquity of Micrometer-Sized Dust Grains in the Dense Interstellar Medium
• Comparing Star Formation on Large Scales in the c2d Legacy Clouds: Bolocam 1.1 mm Dust Continuum Surveys of Serpens, Perseus, and Ophiuchus
• Mapping ices in protostellar environments on 1000 AU scales: Methanol-rich ice in the envelope of Serpens SMM 4
• Observational $5-20\mu$m Interstellar Extinction Curves Toward Star-Forming Regions Derived from Spitzer IRS Spectra
• Microscopic simulation of methanol and formaldehyde ice formation in cold dense cores
• Ice and Dust in the Quiescent Medium of Isolated Dense Cores
• Gaia-DR2 confirms VLBA parallaxes in Ophiuchus, Serpens and Aquila
• Origin of the 6.85 micron band near young stellar objects: The ammonium ion (NH4+) revisited
• Envelope structure of deeply embedded young stellar objects in the Serpens Molecular Cloud
• The Relationship between the Optical Depth of the 9.7 micron Silicate Absorption Feature and Infrared Differential Extinction in Dense Clouds
• The 9.7 and 18 um silicate absorption profiles towards diffuse and molecular cloud lines-of-sight
• Formation of interstellar methanol ice prior to the heavy CO freeze-out stage
• Infrared Spectroscopic Survey of the Quiescent Medium of Nearby Clouds: I. Ice Formation and Grain Growth in Lupus
• MARCS-Model Stellar Atmospheres, and Their Application to the Photometric Calibration of the Spitzer-IRS
• Variation of the extinction law in the Trifid nebula
• Radial velocity photon limits for the dwarf stars of spectral classes F--M
• Linking ice and gas in the Serpens low-mass star-forming region
• Observations of the Onset of Complex Organic Molecule Formation in Interstellar Ices

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