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Evidence of Fast Pebble Growth Near Condensation Fronts in the HL Tau Protoplanetary Disk

Zhang, Ke and Blake, Geoffrey A. and Bergin, Edwin A. (2015) Evidence of Fast Pebble Growth Near Condensation Fronts in the HL Tau Protoplanetary Disk. Astrophysical Journal Letters, 806 (1). Art. No. L7. ISSN 2041-8205. http://resolver.caltech.edu/CaltechAUTHORS:20150710-075519758

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Abstract

Water and simple organic molecular ices dominate the mass of solid materials available for planetesimal and planet formation beyond the water snow line. Here we analyze ALMA long baseline 2.9, 1.3 and 0.87 mm continuum images of the young star HL Tau, and suggest that the emission dips observed are due to rapid pebble growth around the condensation fronts of abundant volatile species. Specifically, we show that the prominent innermost dip at 13 AU is spatially resolved in the 0.87 mm image, and its center radius is coincident with the expected mid-plane condensation front of water ice. In addition, two other prominent dips, at distances of 32 and 63 AU, cover the mid-plane condensation fronts of pure ammonia or ammonia hydrates and clathrate hydrates (especially with CO and N_2) formed from amorphous water ice. The spectral index map of HL Tau between 1.3 and 0.87 mm shows that the flux ratios inside the dips are statistically larger than those of nearby regions in the disk. This variation can be explained by a model with two dust populations, where most of the solid mass resides in a component that has grown to decimeter size scales inside the dips. Such growth is in accord with recent numerical simulations of volatile condensation, dust coagulation, and settling.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/2041-8205/806/1/L7DOIArticle
http://iopscience.iop.org/2041-8205/806/1/L7PublisherArticle
http://arxiv.org/abs/1505.00882arXivDiscussion Paper
Additional Information:© 2015 American Astronomical Society. Received 2015 April 5; accepted 2015 May 4; published 2015 June 4. This paper makes use of the following ALMA data sets: ADS/JAO.ALMA#2011.0.00015.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The authors gratefully acknowledge support provided by the NSF Astronomy & Astrophysics, NSF INSPIRE (AST-1344133), and NASA Origins of Solar Systems grant programs.
Funders:
Funding AgencyGrant Number
NSF Astronomy & AstrophysicsUNSPECIFIED
NSF INSPIREAST-1344133
NASA Origins of Solar SystemsUNSPECIFIED
Subject Keywords:astrochemistry; planets and satellites: composition; protoplanetary disks; stars: individual (HL Tau); stars: pre-main sequence
Record Number:CaltechAUTHORS:20150710-075519758
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150710-075519758
Official Citation: Evidence of Fast Pebble Growth Near Condensation Fronts in the HL Tau Protoplanetary Disk Ke Zhang et al. 2015 ApJ 806 L7
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58832
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:10 Jul 2015 15:56
Last Modified:10 Jul 2015 15:56

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