CHARA/MIRC observations of two M supergiants in Perseus OB1: temperature, Bayesian modeling, and compressed sensing imaging

Two red supergiants of the Per OB1 association, RS Per and T Per, have been observed in H band using the MIRC instrument at the CHARA array. The data show clear evidence of departure from circular symmetry. We present here new techniques specially developed to analyze such cases, based on state-of-the-art statistical frameworks. The stellar surfaces are first modeled as limb-darkened discs based on SATLAS models that fit both MIRC interferometric data and publicly available spectrophotometric data. Bayesian model selection is then used to determine the most probable number of spots. The effective surface temperatures are also determined and give further support to the recently derived hotter temperature scales of red su- pergiants. The stellar surfaces are reconstructed by our model-independent imaging code SQUEEZE, making use of its novel regularizer based on Compressed Sensing theory. We find excellent agreement between the model-selection results and the reconstructions. Our results provide evidence for the presence of near-infrared spots representing about 3-5% of the stellar flux

Magnetospheric Accretion and Ejection of Matter in Resistive Magnetohydrodynamic Simulations

The ejection of matter in the close vicinity of a young stellar object is investigated, treating the accretion disk as a gravitationally bound reservoir of matter. By solving the resistive MHD equations in 2D axisymmetry using our version of the Zeus-3D code with newly implemented resistivity, we study the effect of magnetic diffusivity in the magnetospheric accretion-ejection mechanism. Physical resistivity was included in the whole computational domain so that reconnection is enabled by the physical as well as the numerical resistivity. We show, for the first time, that quasi-stationary fast ejecta of matter, which we call {\em micro-ejections}, of small mass and angular momentum fluxes, can be launched from a purely resistive magnetosphere. They are produced by a combination of pressure gradient and magnetic forces, in presence of ongoing magnetic reconnection along the boundary layer between the star and the disk, where a current sheet is formed. Mass flux of micro-ejection increases with increasing magnetic field strength and stellar rotation rate, and is not dependent on the disk to corona density ratio and amount of resistivity.Comment: 18 pages, many revisions from previous version, accepted in Ap

Rationality as the Rule of Reason

The demands of rationality are linked both to our subjective normative perspective (given that rationality is a person-level concept) and to objective reasons or favoring relations (given that rationality is non-contingently authoritative for us). In this paper, I propose a new way of reconciling the tension between these two aspects: roughly, what rationality requires of us is having the attitudes that correspond to our take on reasons in the light of our evidence, but only if it is competent. I show how this view can account for structural rationality on the assumption that intentions and beliefs as such involve competent perceptions of downstream reasons, and explore various implications of the account

Modelling of particulate matter concentrations and source contributions in the Helsinki Metropolitan Area in 2008 and 2010

We refined an urban-scale dispersion modelling system by adding a road dust suspension model, FORE. The deterministic modelling includes both vehicular exhaust emissions (including cold start and cold driving) and suspended road dust. The urban scale modelling system was used in combination with the regional scale chemical transport model LOTOSEUROS, for 2008, and the measured regional background concentrations, for 2010. The predictions were compared against measured concentrations of PM2.5 and PM10. PM2.5 concentrations were slightly and the PM10concentrations substantially under-predicted in 2008, mainly due to the under-predicted regional background concentration. Source contributions of suspended road dust varied from 2% to 8% and from 12% to 38% for PM2.5 and PM10, respectively. Long-range transported contributions at the urban traffic stations were 72% to 92% for PM2.5 and 50% to 83% for PM10. © 2016

Irregular dust features around intermediate-mass young stars with GPI: signs of youth or misaligned disks?

This is the final version. Available from the American Astronomical Society via the DOI in this recordWe are undertaking a large survey of over thirty disks using the Gemini Planet Imager (GPI) to see whether the observed dust structures match spectral energy distribution (SED) predictions and have any correlation with stellar properties. GPI can observe near-infrared light scattered from dust in circumstellar environments using high-resolution Polarimetric Differential Imaging (PDI) with coronagraphy and adaptive optics. The data have been taken in J and H bands over two years, with inner working angles of 0.08 ” and 0.11 ” respectively. Ahead of the release of the complete survey results, here we present five objects with extended and irregular dust structures within 2 ” of the central star. These objects are: FU Ori; MWC 789; HD 45677; Hen 3-365; and HD 139614. The observed structures are consistent with each object being a pre-main-sequence star with protoplanetary dust. The five objects’ circumstellar environments could result from extreme youth and complex initial conditions, from asymmetric scattering patterns due to shadows cast by misaligned disks, or in some cases from interactions with companions. We see complex Uφ structures in most objects that could indicate multiple scattering or result from the illumination of companions. Specific key findings include the first high-contrast observation of MWC 789 revealing a newly-discovered companion candidate and arc, and two faint companion candidates around Hen 3-365. These two objects should be observed further to confirm whether the companion candidates are co-moving. Further observations and modeling are required to determine the causes of the structures.Science and Technology Facilities Council (STFC

Imaging the disc rim and a moving close-in companion candidate in the pre-transitional disc of V1247 Orionis

This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.Context. V1247 Orionis harbours a pre-transitional disc with a partially cleared gap. Earlier interferometric and polarimetric observations revealed strong asymmetries both in the gap region and in the outer disc. The presence of a companion was inferred to explain these asymmetric structures and the ongoing disc clearing. Aims. Using an extensive set of multi-wavelength and multi-epoch observations we aimed to identify the origin of the previously detected asymmetries. Methods. We observed V1247 Ori at three epochs spanning ∼ 678 days using sparse aperture masking interferometry with Keck/NIRC2 and VLT/NACO. In addition, we search for signs of accretion through VLT/SPHERE-ZIMPOL spectral differential imaging in Hα and R-band continuum. Our SMA sub-millimetre interferometry in 880 µm continuum and in the CO(3-2) line allows us to constrain the orientation and direction of rotation of the outer disc. Results. We find the L’-band emission to be dominated by static features which trace forward-scattered dust emission from the inner edge of the outer disc located to the north-east. In H- and K-band, we see evidence for a companion candidate that moved systematically by 45◦ within the first ∼345 days. The separation of the companion candidate is not well constrained, but the observed position angle change is consistent with Keplerian motion of a body located on a 6 au orbit. From the SMA CO moment map, the location of the disc rim, and the detected orbital motion, we deduced the 3-dimensional orientation of the disc. We see no indication of accretion in Hα and set upper limits for an accreting companion. Conclusions. The measured contrast of the companion candidate in H and K is consistent with an actively accreting protoplanet. Hence, we identify V1247 Ori as a unique laboratory for studying companion-disc interactions and disc clearing.We acknowledge support from an ERC Starting Grant (Grant Agreement No. 639889), STFC Rutherford Fellowship Article number, page 14 of 17 M. Willson et al.: Imaging the disc rim and companion candidate in V1247 Ori (ST/J004030/1), STFC Rutherford Grant (ST/K003445/1), Marie SklodowskaCurie CIG grant (Ref. 618910), and Philip Leverhulme Prize (PLP-2013-110). We additionally acknowledge support from NASA KPDA grants (JPL-1452321, 1474717, 1485953, 1496788). The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. J. Kluska acknowledges support from the research council of the KU Leuven under grant number C14/17/082. M. Curé and S. Kanaan acknowledge financial support from Centro de Astrofísica de Valparaiso. S. Kanaan thank the support of Fondecyt iniciacíon grant No. 11130702. T. Muto is partially supported by JSPS KAKENHI grant No. 26800106

Non-Minimal Supersymmetric Higgs Bosons at LEP2

We discuss the discovery reach of LEP2 for the Higgs sector of a general extension of the MSSM including a single gauge singlet field. This change introduces a new quartic Higgs boson self-coupling which can increase the masses of the CP-even states, and also allows mixing between singlet and non-singlet states which can reduce the couplings of the mass eigenstates to the $Z$. The lightest CP-even Higgs boson is bounded by a parameter $\Lambda$ which takes a maximum value $\Lambda_{max}\approx 136-146$ GeV for top mass $150-195$ GeV. We generalise the discussion of the bound to include the entire CP-even spectrum and show how experiment may exclude values of $\Lambda$ smaller than some $\Lambda_{min}$. CP-even Higgs boson searches at LEP2 will be able to exclude $\Lambda_{min}\approx 81-105$ GeV, depending on the machine parameters. We also present exclusion plots in the $m_A-\tan\beta$ plane, based on an analysis of CP-even, CP-odd and charged Higgs production processes at LEP2.Comment: Plain LaTeX, 33 pages, figures uuencoded and gzipped. Trivial changes and typos corrected for publication in Rhys Rev

Modelling the dispersion of particle numbers in five European cities

We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam, and Athens, in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We used atmospheric dispersion modelling for PNCs in the five target cities and on a European scale, and evaluated the predicted results against available measured concentrations. In all the target cities, the concentrations of particle numbers (PNs) were mostly influenced by the emissions originating from local vehicular traffic. The influence of shipping and harbours was also significant for Helsinki, Oslo, Rotterdam, and Athens, but not for London. The influence of the aviation emissions in Athens was also notable. The regional background concentrations were clearly lower than the contributions originating from urban sources in Helsinki, Oslo, and Athens. The regional background was also lower than urban contributions in traffic environments in London, but higher or approximately equal to urban contributions in Rotterdam. It was numerically evaluated that the influence of coagulation and dry deposition on the predicted PNCs was substantial for the urban background in Oslo. The predicted and measured annual average PNCs in four cities agreed within approximatelyPeer reviewe