Measuring Turbulence in TW Hya with ALMA: Methods and Limitations
| dc.contributor.author | TEAGUE, Richard, | |
| hal.structure.identifier | AMOR 2016 | |
| dc.contributor.author | GUILLOTEAU, S. | |
| dc.contributor.author | SEMENOV, Dmitry, | |
| dc.contributor.author | HENNING, Thomas, | |
| hal.structure.identifier | AMOR 2016 | |
| dc.contributor.author | DUTREY, Anne | |
| hal.structure.identifier | Institut de RadioAstronomie Millimétrique [IRAM] | |
| dc.contributor.author | PIETU, Vincent, | |
| dc.contributor.author | BIRNSTIEL, Tilman, | |
| hal.structure.identifier | AMOR 2016 | |
| dc.contributor.author | CHAPILLON, E. | |
| dc.contributor.author | HOLLENBACH, David, | |
| dc.contributor.author | GORTI, Uma, | |
| dc.date.issued | 2016-05 | |
| dc.identifier.issn | 0004-6361 | |
| dc.description.abstractEn | We obtain high spatial and spectral resolution images of the CO J=2-1, CN N=2-1 and CS J=5-4 emission with ALMA in Cycle~2. The radial distribution of the turbulent broadening is derived with three approaches: two `direct' and one modelling. The first requires a single transition and derives \Tex{} directly from the line profile, yielding a \vturb{}. The second assumes two different molecules are co-spatial thus their relative linewidths allow for a calculation of \Tkin{} and \vturb{}. Finally we fit a parametric disk model where physical properties of the disk are described by power laws, to compare our `direct' methods with previous values. The two direct methods were limited to the outer $r > 40$~au disk due to beam smear. The direct method found \vturb{} ranging from $\approx$~\vel{130} at 40~au, dropping to $\approx$~\vel{50} in the outer disk, qualitatively recovered with the parametric model fitting. This corresponds to roughly $0.2 - 0.4~c_s$. CN was found to exhibit strong non-LTE effects outside $r \approx 140$~au, so \vturb{} was limited to within this radius. The assumption that CN and CS are co-spatial is consistent with observed linewidths only within $r \lesssim 100$~au, within which \vturb{} was found to drop from \vel{100} ($\approx~0.4~c_s$) to nothing at 100~au. The parametric model yielded a near constant \vel{50} for CS ($0.2 - 0.4~c_s$). We demonstrate that absolute flux calibration is and will be the limiting factor in all studies of turbulence using a single molecule. The magnitude of the dispersion is comparable with or below that predicted by the magneto-rotational instability theory. A more precise comparison would require to reach an absolute calibration precision of order 3\%, or to find a suitable combination of light and heavy molecules which are co-located in the disk. | |
| dc.language.iso | en | |
| dc.publisher | EDP Sciences | |
| dc.subject.en | Astrophysics - Solar and Stellar Astrophysics | |
| dc.subject.en | Astrophysics - Astrophysics of Galaxies | |
| dc.title.en | Measuring Turbulence in TW Hya with ALMA: Methods and Limitations | |
| dc.type | Article de revue | |
| dc.identifier.doi | 10.1051/0004-6361/201628550 | |
| dc.subject.hal | Planète et Univers [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO] | |
| dc.identifier.arxiv | 1606.00005 | |
| bordeaux.journal | Astronomy and Astrophysics - A&A | |
| bordeaux.page | id.A49 | |
| bordeaux.volume | 592 | |
| bordeaux.peerReviewed | oui | |
| hal.identifier | hal-01325420 | |
| hal.version | 1 | |
| hal.popular | non | |
| hal.audience | Internationale | |
| hal.origin.link | https://hal.archives-ouvertes.fr//hal-01325420v1 | |
| bordeaux.COinS | ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astronomy%20and%20Astrophysics%20-%20A&A&rft.date=2016-05&rft.volume=592&rft.spage=id.A49&rft.epage=id.A49&rft.eissn=0004-6361&rft.issn=0004-6361&rft.au=TEAGUE,%20Richard,&GUILLOTEAU,%20S.&SEMENOV,%20Dmitry,&HENNING,%20Thomas,&DUTREY,%20Anne&rft.genre=article |
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