Mid-infrared polarization of Herbig Ae/Be discs

Li, Dan; Telesco, C. M.; Zhang, Han; Wright, Cameron H. G.; Pantin, É.; Barnes, Peter J.; Packham, C.

doi:10.1093/mnras/stx2228

Cited by 13 publications

(26 citation statements)

References 97 publications

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“…The SMA, CARMA, and ALMA mapped the inferred magnetic field toward large numbers of low-mass protostellar cores with ∼100-1000 au resolution (e.g., Girart et al 2006;Rao et al 2009;Hull et al 2013Hull et al , 2014Hull et al , 2017aHull et al , 2017bStephens et al 2013;Cox et al 2018), and a few studies with the GTC, SMA, CARMA, and Karl G. Jansky Very Large Array (VLA) searched for (and were sometimes able to marginally resolve) what was assumed to be the magnetic field structure at 100 au scales in a few protostellar and protoplanetary disks (Hughes et al 2009(Hughes et al , 2013Rao et al 2014;Stephens et al 2014;Cox et al 2015;Segura-Cox et al 2015;Li et al 2016Li et al , 2018Fernández-López et al 2016;Liu et al 2016).…”

Section: Introductionmentioning

confidence: 99%

ALMA Observations of Polarization from Dust Scattering in the IM Lup Protoplanetary Disk

Hull

Yang

et al. 2018

ApJ

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We present 870 μm ALMA observations of polarized dust emission toward the Class II protoplanetary disk IMLup. We find that the orientation of the polarized emission is along the minor axis of the disk, and that the value of the polarization fraction increases steadily toward the center of the disk, reaching a peak value of ∼1.1%. All of these characteristics are consistent with models of self-scattering of submillimeter-wave emission from an optically thin inclined disk. The distribution of the polarization position angles across the disk reveals that, while the average orientation is along the minor axis, the polarization orientations show a significant spread in angles; this can also be explained by models of pure scattering. We compare the polarization with that of the Class I/II source HLTau. A comparison of cuts of the polarization fraction across the major and minor axes of both sources reveals that IMLup has a substantially higher polarization fraction than HLTau toward the center of the disk. This enhanced polarization fraction could be due a number of factors, including higher optical depth in HLTau, or scattering by larger dust grains in the more evolved IMLup disk. However, models yield similar maximum grain sizes for both HLTau (72 μm) and IMLup (61 μm, this work). This reveals continued tension between grain-size estimates from scattering models and from models of the dust emission spectrum, which find that the bulk of the (unpolarized) emission in disks is most likely due to millimeter-sized (or even centimeter-sized) grains.

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Section: Introductionmentioning

confidence: 99%

ALMA Observations of Polarization from Dust Scattering in the IM Lup Protoplanetary Disk

Hull

Yang

et al. 2018

ApJ

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“…It is now possible to make polarization maps of the accretion discs at millimeter and (sub)millimeter wavelengths with ALMA. Interpretation of the polarization maps in frame of Davis-Greenstein mechanism allows to determine geometry of the magnetic field in the disc (Stephens et al ⋆ E-mail: dudorov@csu.ru (AED) † E-mail: khaibrakhmanov@csu.ru (SAKh) ‡ E-mail: andrej.sobolev@urfu.ru (AMS) 2014; Li et al 2016Li et al , 2018. Although there are other possible interpretations of the polarization maps (see Lazarian & Hoang 2007;Tazaki et al 2017;Kataoka et al 2017;Stephens et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of magnetic flux tubes in accretion discs of T Tauri stars

Dudorov

Khaibrakhmanov

Соболев

2019

Monthly Notices of the Royal Astronomical Society

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Dynamics of slender magnetic flux tubes (MFT) in the accretion discs of T Tauri stars is investigated. We perform simulations taking into account buoyant, aerodynamic and turbulent drag forces, radiative heat exchange between MFT and ambient gas, magnetic field of the disc. The equations of MFT dynamics are solved using Runge-Kutta method of the fourth order. The simulations show that there are two regimes of MFT motion in absence of external magnetic field. In the region r < 0.2 au, the MFT of radii 0.05 a 0 0.16 H (H is the scale height of the disc) with initial plasma beta of 1 experience thermal oscillations above the disc. The oscillations decay over some time, and MFT continue upward motion afterwards. Thinner or thicker MFT do not oscillate. MFT velocity increases with initial radius and magnetic field strength. MFT rise periodically with velocities up to 5-15 km s −1 and periods of 0.5 −10 yr determined by the toroidal magnetic field generation time. Approximately 20% of disc mass and magnetic flux can escape to disc atmosphere via the magnetic buoyancy over characteristic time of disc evolution. MFT dispersal forms expanding magnetized corona of the disc. External magnetic field causes MFT oscillations near the disc surface. These magnetic oscillations have periods from several days to 1-3 months at r < 0.6 au. The magnetic oscillations decay over few periods. We simulate MFT dynamics in accretion discs in the Chameleon I cluster. The simulations demonstrate that MFT oscillations can produce observed IR-variability of T Tauri stars.

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“…MWC 1080A and MWC 297 are massive Herbig Be stars while HL Tau is a T-Tauri star which is the closest in our sample at 140 pc right before MWC 297 which is at a distance of 250 pc [Li et al (2018); and references therein]. MWC 1080A is comparatively a very young star [Li et al (2014) 2018)].…”

Section: Comparison With Observed Datamentioning

confidence: 82%

“…The amorphous/astronomical silicate and graphite refractive indices used in our dust models have been obtained from Draine (2003) while the SiC optical constants have been taken from Pégourié et al (1988). Li et al (2018) have studied the magnetic fields of protoplanetary disks by measuring the polarization of pre-main sequence stars using CanariCam, a high-resolution MIR imaging instrument (7.5-25 µm) mounted over the 10.4 metres reflecting telescope, Gran Telescopio Canarias (GTC), situated at La Palma, Spain [Telesco et al (2003); Packham et al (2005)]. Observations made by them at 8.7, 10.3 and 12.5 µm were selected such that they could sample the 10 µm silicate polarization feature which is ideally what we are trying to do from our composite grain models.…”

Section: Composite Dust Grain Modelsmentioning

confidence: 99%

“…They have separated the emission and absorption components of the star sample depending on the difference in polarization spectra across the 10 µm peak. The details of observation and data reduction using CanariCam have been presented in Zhang et al (2017a); Zhang et al (2017b) and Li et al (2018). Two Herbig Be stars and one T-Tauri star showing polarization in absorption have been considered for this work from the sample of observations made by Li et al (2018) to compare with the linear polarization that we have calculated from the composite grain models.…”

Section: Composite Dust Grain Modelsmentioning

confidence: 99%

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Modelling the mid-infrared polarization in dust around young stars

Saikia

Gogoi

Gupta

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The presence of crystalline silicates has been detected in the circumstellar environment of several young stars in the recent past and there is evidence of silicon carbide (SiC) detection in the envelope of pre-main sequence star SVS13. In this work, we have attempted to probe the presence of SiC in the dust around protoplanetary disks in a sample of young stars. We have modelled the linear polarization of composite dust grains in the mid-infrared (MIR: 8-13 µm) using silicates as the host with various inclusions of SiC and graphites using the Discrete Dipole Approximation (DDA) and the Effective Medium Approximation (EMA) T-Matrix methods. We have then compared our modelling results with polarimetric observations made in the protoplanetary disks surrounding two Herbig Be stars and one T-Tauri star with particular emphasis towards the 10 µm silicate feature using CanariCam mounted over the Gran Telescopio Canarias (GTC). We report the possible existence of SiC in the outer disk/envelope around one star in our sample which has been interpreted based on the shape, size, composition and fraction of inclusions by volume in our dust grain models.

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Mid-infrared polarization of Herbig Ae/Be discs

Cited by 13 publications

References 97 publications

ALMA Observations of Polarization from Dust Scattering in the IM Lup Protoplanetary Disk

ALMA Observations of Polarization from Dust Scattering in the IM Lup Protoplanetary Disk

Dynamics of magnetic flux tubes in accretion discs of T Tauri stars

Modelling the mid-infrared polarization in dust around young stars

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