2016/05/13 by Catherine Walsh, Ryan A. Loomis, Karin I. Oberg +10 · 217 citations
Chemistry · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Chemistry #Environmental science #Gas phase #Materials science #Methanol #Molecular Spectroscopy and Structure #Physics #Planet #Protoplanetary disk #Thermodynamics #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.3847/2041-8205/823/1/l10
published in The Astrophysical Journal Letters 823(1), L10 (IOP Publishing) · 14 pages, 4 figures, 1 table, published online in ApJL on 13th May 2016
openalex publication_date 2016/05/13 · arxiv created 2016/06/21 · arxiv updated 2016/06/22 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
ABSTRACT The first detection of gas-phase methanol in a protoplanetary disk (TW Hya) is presented. In addition to being one of the largest molecules detected in disks to date, methanol is also the first disk organic molecule with an unambiguous ice chemistry origin. The stacked methanol emission, as observed with the Atacama Large Millimeter/submillimeter Array, is spectrally resolved and detected across six velocity channels ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>></mml:mo> <mml:mn>3</mml:mn> <mml:mi>σ</mml:mi> </mml:math> ), reaching a peak signal-to-noise of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>5.5</mml:mn> <mml:mi>σ</mml:mi> </mml:math> , with the kinematic pattern expected for TW Hya. Using an appropriate disk model, a fractional abundance of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>3</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> <mml:mo>–</mml:mo> <mml:mn>4</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>11</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> (with respect to H 2 ) reproduces the stacked line profile and channel maps, with the favored abundance dependent upon the assumed vertical location (midplane versus molecular layer). The peak emission is offset from the source position, suggesting that the methanol emission has a ring-like morphology: the analysis here suggests it peaks at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>≈</mml:mo> <mml:mn>30</mml:mn> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">au</mml:mi> </mml:math> , reaching a column density <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>3</mml:mn> <mml:mo>–</mml:mo> <mml:mn>6</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> cm −2 . In the case of TW Hya, the larger (up to millimeter-sized) grains, residing in the inner 50 au, may thus host the bulk of the disk ice reservoir. The successful detection of cold gas-phase methanol in a protoplanetary disk implies that the products of ice chemistry can be explored in disks, opening a window into studying complex organic chemistry during planetary system formation.