NEW SPATIALLY RESOLVED OBSERVATIONS OF THE T Cha TRANSITION DISK AND CONSTRAINTS ON THE PREVIOUSLY CLAIMED SUBSTELLAR COMPANION

Sallum, Steph; Eisner, J. A.; Close, Laird M.; Hinz, Philip M.; Skemer, Andrew J.; Bailey, Vanessa P.; Briguglio, Runa; Follette, Katherine B.; Males, Jared R.; Morzinski, Katie M.; Puglisi, Alfio; Rodigas, Timothy J.; Weinberger, Alycia J.; Xompero, Marco

doi:10.1088/0004-637x/801/2/85

Cited by 24 publications

(42 citation statements)

References 71 publications

(102 reference statements)

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“…Model 7: A point source plus a skewed Gaussian ring with a diameter of 300 mas and 70% skew amplitude. Skew has been observed in NRM observations of transition disks (e.g., Huélamo et al 2011;Cheetham et al 2015;Sallum et al 2015a Kraus & Ireland 2012;Sallum et al 2015b). …”

Section: Discussionmentioning

confidence: 95%

“…In this scenario it would be possible to calibrate toward the wrong companion signal by selecting a noise spike rather than the true signal. This highlights the importance of quantifying Type 1 and Type 2 errors in NRM companion modeling (e.g., Sallum et al 2015a). At these contrasts, Polycal recovers the input signal in both data sets, although the parameter uncertainties are large.…”

Section: Calibration Comparisonmentioning

confidence: 90%

“…Closure phases are particularly powerful for companion detections since they are sensitive to asymmetries and are unaffected by atmospheric phase offsets. Because closure phases are correlated, we then project them into linearly independent quantities called kernel phases (e.g., Martinache 2010;Ireland 2013;Sallum et al 2015a). We apply both model fitting and image reconstruction to understand the source morphology.…”

Section: Methodsmentioning

confidence: 99%

“…To calculate kernel phases, we assume that our observed phase vector, F, can be written as a linear combination of instrumental phases, f, plus any intrinsic source phase 0 F (following the notation in Sallum et al 2015a):…”

Section: Kernel Phase Projectionmentioning

confidence: 99%

“…It can detect sources with moderate contrast (∼1:100) at separations as small as 0.5 λ/D, expanding the companion discovery phase space. NRM has led to the detection of stellar (e.g., Ireland & Kraus 2008;Biller et al 2012) companions, substellar companions (e.g., Kraus & Ireland 2012;Sallum et al 2015b), and circumstellar disk features (e.g., Cheetham et al 2015;Sallum et al 2015a) at or even within the diffraction limit. This makes it particularly useful for direct planet formation studies, where most targets are at distances of >100 pc.…”

Section: Introductionmentioning

confidence: 99%

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Data Reduction and Image Reconstruction Techniques for Non-redundant Masking

Sallum

Eisner

2017

ApJS

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The technique of non-redundant masking (NRM) transforms a conventional telescope into an interferometric array. In practice, this provides a much better constrained point-spread function than a filled aperture and thus higher resolution than traditional imaging methods. Here, we describe an NRM data reduction pipeline. We discuss strategies for NRM observations regarding dithering patterns and calibrator selection. We describe relevant image calibrations and use example Large Binocular Telescope data sets to show their effects on the scatter in the Fourier measurements. We also describe the various ways to calculate Fourier quantities, and discuss different calibration strategies. We present the results of image reconstructions from simulated observations where we adjust prior images, weighting schemes, and error bar estimation. We compare two imaging algorithms and discuss implications for reconstructing images from real observations. Finally, we explore how the current state of the art compares to next-generation Extremely Large Telescopes.

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Section: Discussionmentioning

confidence: 95%

Section: Calibration Comparisonmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Kernel Phase Projectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Data Reduction and Image Reconstruction Techniques for Non-redundant Masking

Sallum

Eisner

2017

ApJS

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Accreting protoplanets in the LkCa 15 transition disk

Sallum

Follette

Eisner

et al. 2015

Nature

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308

408

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Exoplanet detections have revolutionized astronomy, offering new insights into solar system architecture and planet demographics. While nearly 1900 exoplanets have now been discovered and confirmed, 1 none are still in the process of formation. Transition discs, protoplanetary disks with inner clearings 2-4 best explained by the influence of accreting planets 5 , are natural laboratories for the study of planet formation. Some transition discs show evidence for the presence of young planets in the form of disc asymmetries 6, 7 or infrared sources detected within their clearings, as in the case of LkCa 15. 8,9 Attempts to observe directly sig-Author Contributions: This work merged two independently acquired and analysed data sets. S.S. led preparation of the manuscript, the orbital fits, and the acquisition and analysis of the LBT data while K.B.F. led the acquisition and analysis of the MagAO data, development of the MagAO SDI pipeline, and drafted MagAO manuscript sections.

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New constraints on the disk characteristics and companion candidates around T Chamaeleontis with VLT/SPHERE

Pohl

Sissa

Langlois

et al. 2017

A&A

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Context. The transition disk around the T Tauri star T Cha possesses a large gap, making it a prime target for high-resolution imaging in the context of planet formation. Aims. We aim to find signs of disk evolutionary processes by studying the disk geometry and the dust grain properties at its surface, and to search for companion candidates. Methods. We analyze a set of VLT/SPHERE data at near-infrared and optical wavelengths. We performed polarimetric imaging of T Cha with IRDIS (1.6 µm) and ZIMPOL (0.5-0.9 µm), and obtained intensity images from IRDIS dual-band imaging with simultaneous spectro-imaging with IFS (0.9-1.3 µm).Results. The disk around T Cha is detected in all observing modes and its outer disk is resolved in scattered light with unprecedented angular resolution and signal-to-noise. The images reveal a highly inclined disk with a noticeable east-west brightness asymmetry. The significant amount of non-azimuthal polarization signal in the U φ images, with a U φ /Q φ peak-to-peak value of 14%, is in accordance with theoretical studies on multiple scattering in an inclined disk. Our optimal axisymmetric radiative transfer model considers two coplanar inner and outer disks, separated by a gap of 0 . 28 (∼30 au) in size, which is larger than previously thought. We derive a disk inclination of ∼69 deg and PA of ∼114 deg. In order to self-consistently reproduce the intensity and polarimetric images, the dust grains, responsible for the scattered light, need to be dominated by sizes of around ten microns. A point source is detected at an angular distance of 3.5 from the central star. It is, however, found not to be co-moving. Conclusions. We confirm that the dominant source of emission is forward scattered light from the near edge of the outer disk. Our point source analysis rules out the presence of a companion with mass larger than ∼8.5 M jup between 0 . 1 and 0 . 3. The detection limit decreases to ∼2 M jup for 0 . 3 to 4.0 .

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NEW SPATIALLY RESOLVED OBSERVATIONS OF THE T Cha TRANSITION DISK AND CONSTRAINTS ON THE PREVIOUSLY CLAIMED SUBSTELLAR COMPANION

Cited by 24 publications

References 71 publications

Data Reduction and Image Reconstruction Techniques for Non-redundant Masking

Data Reduction and Image Reconstruction Techniques for Non-redundant Masking

Accreting protoplanets in the LkCa 15 transition disk

New constraints on the disk characteristics and companion candidates around T Chamaeleontis with VLT/SPHERE

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