ALMA imaging of the CO snowline of the HD 163296 disk with DCO<sup>+</sup>

Mathews, Geoffrey S.; Klaassen, Pamela; Juhász, A.; Harsono, Daniel; Chapillon, E.; Dishoeck, E. F. van; Espada, Daniel; Gregorio-Monsalvo, I. de; Hales, Antonio; Hogerheijde, M. R.; Mottram, J. C.; Rawlings, Mark G.; Takahashi, Sanemichi Z.; Testi, L.

doi:10.1051/0004-6361/201321600

Cited by 112 publications

(176 citation statements)

References 45 publications

(62 reference statements)

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“…In this scenario, an enhanced abundance of small fragmented silicate grains at temperatures of 160 K may contribute significantly to the amorphous silicate features. The role of this particular snow line in the evolution of solids may be further investigated by direct observations of the snow line such as for HD 16296 (Mathews et al 2013) and TW Hya (Qi et al 2013). …”

Section: Discussionmentioning

confidence: 99%

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Khalafinejad

Maaskant

Mariñas

et al. 2016

A&A

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Context. The formation of dust gaps in protoplanetary disks is one of the most important signs of disk evolution and might indicate the formation of planets. Aims. We aim to characterize the flaring disk structure around the Herbig Ae/Be stars HD 100453 and HD 34282. Their spectral energy distributions (SEDs) show an emission excess between 15−40 µm, but very weak (HD 100453) and no (HD 34282) signs of the 10 and 20 µm amorphous silicate features. We investigate whether this implies the presence of large dust gaps. Methods. We investigated spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE. We performed radiative transfer modeling and examined the radial distribution of dust. We simultaneously fit the Q-band images and SEDs of HD 100453 and HD 34282. Results. Our solutions require that the inner halos and outer disks be separated by large dust gaps that are depleted with respect to the outer disk by a factor of 1000 or more. The inner edges of the outer disks of HD 100453 and HD 34282 have temperatures of ∼160 ± 10 K and ∼60 ± 5 K, respectively. Because of the high surface brightness of these walls, they dominate the emission in the Q band. Their radii are constrained at 20 +2 −2 AU and 92 +31 −17 AU, respectively. Conclusions. HD 100453 and HD 34282 most likely have disk dust gaps. The upper limit of the dust mass in each gap is estimated to be about 10 −7 M . We find that the locations and sizes of disk dust gaps are connected to the SED, as traced by the mid-infrared flux ratio F 30 /F 13.5 . We propose a new classification scheme for the Meeus groups based on the F 30 /F 13.5 ratio. The absence of amorphous silicate features in the observed SEDs is caused by the depletion of small ( 1 µm) silicate dust at temperatures above 160 K, which could be related to the presence of a dust gap in that region of the disk.

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Section: Discussionmentioning

confidence: 99%

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Khalafinejad

Maaskant

Mariñas

et al. 2016

A&A

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“…The ones in the upper side band were #1 (356.50−356.97 GHz) with 122 kHz channel width and #0 (360.11−360.23 GHz) at a high spectral resolution of 30.5 kHz; these included the emission lines: CO(3−2) at 345.796 GHz (#2), HCO + (4−3) at 356.734 GHz (#1), H 13 CO + (4−3) at 346.998 GHz (#3) and DCO + (5−4) at 360.160 GHz (#0). A detailed analysis of these spectral lines has been published by Mathews et al (2013), de Gregorio-Monsalvo et al (2013, and Rosenfeld et al (2013). In this work we focus Fig.…”

Section: Alma Observationsmentioning

confidence: 99%

“…We extracted the DCO + (J = 5−4) emission lines at 360.160 GHz from the ALMA Band 7 observations in order to compare the dust continuum radial profile with a potential molecular tracer of the CO snowline (see Mathews et al 2013). We used the CASA task "clean" with natural weighting to produce an integrated map of the DCO + emission in the velocity range 0.8−10 km s −1 , and the resulting synthesized beam is 0.62 × 0.42 .…”

Section: Dco + Emissionmentioning

confidence: 99%

“…To study the dust properties in the protoplanetary disk around HD 163296, we re-analyse the ALMA science verification observations (de Gregorio-Monsalvo et al 2013;Mathews et al 2013;Rosenfeld et al 2013) and for the first time discuss the continuum emission in Band 6, combined with new VLA observations from the Disks@EVLA collaboration. In Sect.…”

Section: Introductionmentioning

confidence: 99%

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Dust properties across the CO snowline in the HD 163296 disk from ALMA and VLA observations

Guidi

Tazzari

Testi

et al. 2016

A&A

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Context. To characterize the mechanisms of planet formation it is crucial to investigate the properties and evolution of protoplanetary disks around young stars, where the initial conditions for the growth of planets are set. The high spatial resolution of Atacama Large Millimeter/submillimeter Array (ALMA) and Karl G. Jansky Very Large Array (VLA) observations now allows the study of radial variations of dust properties in nearby resolved disks and the investigation of the early stages of grain growth in disk midplanes. Aims. Our goal is to study grain growth in the well-studied disk of the young, intermediate-mass star HD 163296 where dust processing has already been observed and to look for evidence of growth by ice condensation across the CO snowline, which has already been identified in this disk with ALMA. Methods. Under the hypothesis of optically thin emission, we compare images at different wavelengths from ALMA and VLA to measure the opacity spectral index across the disk and thus the maximum grain size. We also use a Bayesian tool based on a two-layer disk model to fit the observations and constrain the dust surface density. Results. The measurements of the opacity spectral index indicate the presence of large grains and pebbles (≥1 cm) in the inner regions of the disk (inside ∼50 AU) and smaller grains, consistent with ISM sizes, in the outer disk (beyond 150 AU). Re-analyzing ALMA Band 7 science verification data, we find (radially) unresolved excess continuum emission centered near the location of the CO snowline at ∼90 AU. Conclusions. Our analysis suggests a grain size distribution consistent with an enhanced production of large grains at the CO snowline and consequent transport to the inner regions. Our results combined with the excess in infrared scattered light suggests there is a structure at 90 AU involving the whole vertical extent of the disk. This could be evidence of small scale processing of dust at the CO snowline.

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“…N 2 H + is enhanced when its main destroyer, CO, freezes out. Another example is the CO snow line in the HD 163296 disk imaged in CO isotopologs and in the DCO + ion, whose abundance peaks when CO freezes out (see § 7.1) 234,235 .…”

Section: Protoplanetary Disksmentioning

confidence: 99%

Astrochemistry of dust, ice and gas: introduction and overview

Dishoeck

Ewine²

2014

Faraday Discuss.

131

102

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A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented, aimed at non-specialists. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other. Much of the chemistry in star- and planet-forming regions is now thought to be driven by gas-grain chemistry rather than pure gas-phase chemistry, and a critical discussion of the state of such models is given. Recent developments in studies of diffuse clouds and PDRs, cold dense clouds, hot cores, protoplanetary disks and exoplanetary atmospheres are summarized, both for simple and more complex molecules, with links to papers presented in this volume. In spite of many lingering uncertainties, the future of astrochemistry is bright: new observational facilities promise major advances in our understanding of the journey of gas, ice and dust from clouds to planets.Comment: Introductory paper for Faraday Discussions 168 conference, April 201

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ALMA imaging of the CO snowline of the HD 163296 disk with DCO⁺

Cited by 112 publications

References 45 publications

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Dust properties across the CO snowline in the HD 163296 disk from ALMA and VLA observations

Astrochemistry of dust, ice and gas: introduction and overview

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ALMA imaging of the CO snowline of the HD 163296 disk with DCO+

Cited by 112 publications

References 45 publications

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Large dust gaps in the transitional disks of HD 100453 and HD 34282

Dust properties across the CO snowline in the HD 163296 disk from ALMA and VLA observations

Astrochemistry of dust, ice and gas: introduction and overview

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ALMA imaging of the CO snowline of the HD 163296 disk with DCO⁺