Tracing the young massive high-eccentricity binary system $\theta^{\mathsf 1}$Orionis C through periastron passage

Kraus, Stefan; Weigelt, G.; Balega, Y. Y.; Docobo, J. A.; Hofmann, K.-H.; Preibisch, Thomas; Schertl, D.; Tamazian, V. S.; Driebe, T.; Ohnaka, K.; Petrov, R.; Schöller, M.; Smith, Michael D.

doi:10.1051/0004-6361/200810368

Cited by 108 publications

(118 citation statements)

References 45 publications

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“…As illustrated in Fig. 3 of Kraus et al (2009), binaries with such a wide separation cause a high-frequency cosine modulation in the wavelength-differential visibilities and closure phases (this argument holds as long as the separation is large compared to the diameter of the individual components). Neither the measured visibilities nor closure phases show such a systematic, wavelength-differential modulation (Figs.…”

Section: Binary: Asymmetric Two-component Gaussian Modelmentioning

confidence: 97%

“…This software employs the P2VM algorithm (Tatulli et al 2007) to derive wavelength-dependent visibilities and closure phases (CP). The wavelength calibration was done using the procedure described in Appendix A of Kraus et al (2009). Following the standard AMBER data reduction procedure, we select the 10% of interferograms with the best signal-to-noise (SNR) ratio.…”

Section: Observationsmentioning

confidence: 99%

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Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

Kraus¹,

Hofmann²,

Malbet

et al. 2009

A&A

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Context. Unveiling the structure of the disks around intermediate-mass pre-main-sequence stars (Herbig Ae/Be stars) is essential for our understanding of the star and planet formation process. In particular, models predict that in the innermost AU around the star, the dust disk forms a "puffed-up" inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination.Aims. Our aim is to constrain the sub-AU geometry of the inner disk around the Herbig Ae star R CrA and search for the predicted asymmetries. Methods. Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H-and K-band) spectrointerferometric observations on R CrA. Observing with three telescopes in a linear array configuration, each data set samples three equally spaced points in the visibility function, providing direct information about the radial intensity profile. In addition, the observations cover a wide position angle range (∼97 • ), also probing the position angle dependence of the source brightness distribution. Results. In the derived visibility function, we detect the signatures of an extended (Gaussian FWHM ∼ 25 mas) and a compact component (Gaussian FWHM ∼ 5.8 mas), with the compact component contributing about two-thirds of the total flux (both in H-and K-band). The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to ∼40 • ) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ various geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. For the binary and vertical rim model, no acceptable fits could be obtained. On the other hand, the skewed ring model and the curved puffed-up inner rim model allow us to simultaneously reproduce the measured visibilities and closure phases. From these models we derive the location of the dust sublimation radius (∼0.4 AU), the disk inclination angle (∼35 • ), and a north-south disk orientation (PA ∼ 180−190 • ). Our curved puffed-up rim model can reproduce reasonably well the interferometric observables and the SED and suggests a luminosity of ∼29 L and the presence of relatively large ( > ∼ 1.2 μm) Silicate dust grains. Our study also reveals discrepancies between the measured interferometric observables and the puffed-up inner rim models, providing important constraints for future refinements of these theoretical models. Perpendicular to the disk, two bow shock-like structures appear in the associated reflection nebula NGC 6729, suggesting that the detected sub-AU size disk is the driving engine of a large-scale outflow. Conclusions. Detecting, for the first time, strong non-localized asymmetries in the inner regions of a Herbig Ae disk, our study supports the existence of a puffed-up inner rim in YSO disks.

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Section: Binary: Asymmetric Two-component Gaussian Modelmentioning

confidence: 97%

Section: Observationsmentioning

confidence: 99%

Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

Kraus¹,

Hofmann²,

Malbet

et al. 2009

A&A

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“…A particularly interesting result of these speckle observations was the discovery of a close (33 mas, ∼15 AU) visual companion to θ 1 Ori C, the most massive star in the cluster. Kraus et al (2007Kraus et al ( , 2009) followed the orbital motion of this system. They used speckle observations, and several interferometric data taken with IOTA and the Astronomical MultiBeam Combiner (AMBER) at ESOs Very Large Telescope Interferometer (VLTI).…”

Section: Introductionmentioning

confidence: 99%

The multiplicity of massive stars in the Orion Nebula Cluster as seen with long-baseline interferometry

Grellmann

Preibisch

Ratzka

et al. 2013

A&A

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Context. The characterization of multiple stellar systems is an important ingredient for testing current star formation models. Stars are more often found in multiple systems, the more massive they are. A complete knowledge of the multiplicity of high-mass stars over the full range of orbit separations is thus essential to understand their still debated formation process. Aims. Infrared long baseline interferometry is very well suited to close the gap between spectroscopic and adaptive optics searches. Observations of the Orion Nebula Cluster (ONC) in general and the Trapezium Cluster in particular can help to answer the question about the origin and evolution of multiple stars. Earlier studies provide a good knowledge about the multiplicity of the stars at very small (spectroscopic companions) and large separations (AO, speckle companions) and thus make the ONC a good target for such a project. Methods. We used the near infrared interferometric instrument AMBER at ESOs Very Large Telescope Interferometer to observe a sample of bright stars in the ONC. We complement our data set by archival NACO observations of θ 1 Ori A to obtain more information about the orbit of the close visual companion. Results. Our observations resolve the known multiple systems θ 1 Ori C and θ 1 Ori A and provide new orbit points, which confirm the predicted orbit and the determined stellar parameters for θ 1 Ori C. Combining AMBER and NACO data for θ 1 Ori A we were able to follow the (orbital) motion of the companion from 2003 to 2011. We furthermore find hints for a companion around θ 1 Ori D, whose existence has been suggested already before, and a previously unknown companion to NU Ori. With a probability of ∼90% we can exclude further companions with masses of ≥3 M around our sample stars for separations between ∼2 mas and ∼110 mas. Conclusions. We conclude that the companion around θ 1 Ori A is most likely physically related to the primary star and not only a chance projected star. The newly discovered possible companions further increase the multiplicity in the ONC. For our sample of two O and three B-type stars we find on average 2.5 known companions per primary, which is around five times more than for low-mass stars.

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“…The strength of the method is the generation of a well defined degree of mass segregation that is controlled via one single parameter, S , and the creation of dynamically consistent models by modelling local potentials and velocities in a quasi-equilibrium state. The so-called index of mass segregation covers the range 3 This estimate is based on the following reference values: the mean stellar separation in the Orion nebula cluster is about 2.5 pc/4000 1/3 ≈ 0.15 pc ≈ 30 000 AU; the HST has a resolution of ∼50 AU at an assumed distance of 400 pc (Menten et al 2007;Jeffries 2007;Kraus et al 2009). Thus, binaries with separations < ∼ 10 −3 would remain unresolved.…”

Section: Primordial Mass-segregationmentioning

confidence: 99%

A highly efficient measure of mass segregation in star clusters

Olczak

Spurzem

Henning

2011

A&A

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Context. Investigations of mass segregation are of vital interest for the understanding of the formation and dynamical evolution of stellar systems on a wide range of spatial scales. A consistent analysis requires a robust measure among different objects and well-defined comparison with theoretical expectations. Various methods have been used for this purpose but usually with limited significance, quantifiability, and application to both simulations and observations. Aims. We aim at developing a measure of mass segregation with as few parameters as possible, robustness against peculiar configurations, independence of mass determination, simple implementation, stable algorithm, and that is equally well adoptable for data from either simulations or observations. Methods. Our method is based on the minimum spanning tree (MST) that serves as a geometry-independent measure of concentration.Compared to previous such approaches we obtain a significant refinement by using the geometrical mean as an intermediate-pass. Results. The geometrical mean boosts the sensitivity compared to previous applications of the MST. It thus allows the detection of mass segregation with much higher confidence and for much lower degrees of mass segregation than other approaches. The method shows in particular very clear signatures even when applied to small subsets of the entire population. We confirm with high significance strong mass segregation of the five most massive stars in the Orion nebula cluster (ONC). Conclusions. Our method is the most sensitive general measure of mass segregation so far and provides robust results for both data from simulations and observations. As such it is ideally suited for tracking mass segregation in young star clusters and to investigate the long standing paradigm of primordial mass segregation by comparison of simulations and observations.

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Tracing the young massive high-eccentricity binary system $\theta^{\mathsf 1}$Orionis C through periastron passage

Cited by 108 publications

References 45 publications

Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae

The multiplicity of massive stars in the Orion Nebula Cluster as seen with long-baseline interferometry

A highly efficient measure of mass segregation in star clusters

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