Angle-dependent radiative grain alignment

Andersson, B. G.; Pintado, O. I.; Potter, S.; Straižys, V.; Charcos-Llorens, M.

doi:10.1051/0004-6361/201117670

Cited by 44 publications

(54 citation statements)

References 33 publications

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“…• periods and the good agreement between angular peaks at 100 and 350 µm we find strong evidence for a detection of the predicted angular dependence of RATs This work, taken together with the optical work towards HD 97300 (Andersson et al 2011), provides the best current tests of the RAT-predicted angular alignment dependence.…”

Section: Based On the Low Faps For 180supporting

confidence: 67%

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A Far-Infrared Observational Test of the Directional Dependence in Radiative Grain Alignment

Vaillancourt

Andersson

2015

ApJ

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The alignment of interstellar dust grains with magnetic fields provides a key method for measuring the strength and morphology of the fields. In turn, this provides a means to study the role of magnetic fields from diffuse gas to dense star-forming regions. The physical mechanism for aligning the grains has been a long-term subject of study and debate. The theory of radiative torques, in which an anisotropic radiation field imparts sufficient torques to align the grains while simultaneously spinning them to high rotational velocities, has passed a number of observational tests. Here we use archival polarization data in dense regions of the Orion molecular cloud (OMC-1) at 100, 350, and 850 µm to test the prediction that the alignment efficiency is dependent upon the relative orientations of the magnetic field and radiation anisotropy. We find that the expected polarization signal, with a 180-degree period, exists at all wavelengths out to radii of 1.5 arcminutes centered on the BNKL object in OMC-1. The probabilities that these signals would occur due to random noise are low ( 1%), and are lowest towards BNKL compared to the rest of the cloud. Additionally, the relative magnetic field to radiation anisotropy directions accord with theoretical predictions in that they agree to better than 15• at 100 µm and 4• at 350 µm.

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Section: Based On the Low Faps For 180supporting

confidence: 67%

“…The analysis presented here can also be applied to the optical polarization data around the star HD 97300, where Andersson et al (2011) found a strong signal and peak alignment efficiency within 10…”

Section: Periodogramsmentioning

confidence: 91%

A Far-Infrared Observational Test of the Directional Dependence in Radiative Grain Alignment

Vaillancourt

Andersson

2015

ApJ

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“…Such a phenomenon is reported in the diffuse interstellar medium around a bright star (e.g., Andersson & Potter 2010;Andersson et al 2011), and a similar mechanism may work in the environment with a lack of radiation produced by the starless core. The linearity in the P H versus H K s -relationship cannot reject the possibility of the mechanism, because the radiative torque effect is an angular one.…”

Section: C Fittingmentioning

confidence: 53%

Distortion of Magnetic Fields in a Starless Core II: 3D Magnetic Field Structure of FeSt 1-457

Kandori

Tamura

Tomisaka

et al. 2017

ApJ

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Three-dimensional (3D) magnetic field information on molecular clouds and cores is important for revealing their kinematical stability (magnetic support) against gravity, which is fundamental for studying the initial conditions of star formation. In the present study, the 3D magnetic field structure of the dense starless core FeSt 1-457 is determined based on the near-infrared polarimetric observations of the dichroic polarization of background stars and simple 3D modeling. With an obtained angle of line-of-sight magnetic inclination axis inc q of 45 10    and previously determined plane-of-sky magnetic field strength B pol of 23.8±12.1 G m , the total magnetic field strength for FeSt 1-457 is derived to be 33.7±18.0 G m . The critical mass of FeSt 1-457, evaluated using both magnetic and thermal/turbulent support is M 3.70 0.92 cr =  M  , which is identical to the observed core mass, M 3.55 0.75 core =  M  . We thus conclude that the stability of FeSt 1-457 is in a condition close to the critical state. Without infalling gas motion and no associated young stars, the core is regarded to be in the earliest stage of star formation, i.e., the stage just before the onset of dynamical collapse following the attainment of a supercritical condition. These properties could make FeSt 1-457 one of the best starless cores for future studies of the initial conditions of star formation.

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“…The uncertainty on the intrinsic color is directly linked to the spectral type uncertainty. The latter is assumed to be of one sub-class consistent with other work (Andersson et al 2011;Torres et al 2006). In the case of stars with only the effective temperature, its uncertainty comprises the uncertainty on the spectral type.…”

Section: Reddening Turn-on Distancementioning

confidence: 93%

A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho–Gaia Astrometric Solution

Voirin¹,

Manara²,

Prusti³

2018

A&A

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Context. The determination of the distance to dark star-forming clouds is a key parameter to derive the properties of the cloud itself, and of its stellar content. This parameter is still loosely constrained even in nearby star-forming regions. Aims. We want to determine the distances to the clouds in the Chamaeleon-Musca complex and to explore the connection between these clouds and the large scale cloud structures in the galaxy. Methods. We use the newly estimated distances obtained from the parallaxes measured by the Gaia satellite and included in the Tycho-Gaia Astrometric Solution catalog. When known members of a region are included in this catalog we use their parallaxes to infer the distance to the cloud. Otherwise, we analyze the dependence of the color excess on the distance of the stars and look for a turn-on of this excess, which is a proxy of the position of the front-edge of the star-forming cloud. Results. We are able to measure the distance to the three Chamaeleon clouds. The distance to Chamaeleon I is 179 +11+11 −10−10 pc, where the quoted uncertainties are statistical and systematic uncertainties, respectively, ∼20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181 +6+11 −5−10 pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199 +8+12 −7−11 pc. Finally, the distance of the Musca cloud is smaller than 603 +91+133pc. These estimates do not allow us to distinguish between the possibility that the Chamaeleon clouds are part of a sheet of clouds parallel to the galactic plane, or perpendicular to it. Conclusions. We have measured a larger distance to the Chamaeleon I cloud than assumed in the past, confirmed the distance to the Chamaeleon II region, and measured for the first time the distance to the Chamaleon III cloud. These values are consistent with the scenario where the three clouds are part of a single large scale structure. Gaia Data Release 2 will allow us to put more stringent constraints on the distances to these clouds by giving us access to parallax measurements for a larger number of members of these regions.

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Angle-dependent radiative grain alignment

Cited by 44 publications

References 33 publications

A Far-Infrared Observational Test of the Directional Dependence in Radiative Grain Alignment

A Far-Infrared Observational Test of the Directional Dependence in Radiative Grain Alignment

Distortion of Magnetic Fields in a Starless Core II: 3D Magnetic Field Structure of FeSt 1-457

A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho–Gaia Astrometric Solution

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