| 1. |
- Aad, G, et al.
(author)
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- 2015
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swepub:Mat__t
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| 2. |
- Kraus, Stefan, et al.
(author)
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Planet Formation Imager (PFI) : Science vision and key requirements
- 2016
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In: Optical and Infrared Interferometry and Imaging V. - : SPIE. - 9781510601932 ; 9907
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Conference paper (peer-reviewed)abstract
- The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ∼100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.
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| 3. |
- Gardner, Tyler, et al.
(author)
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Precision Orbit of delta Delphini and Prospects for Astrometric Detection of Exoplanets
- 2018
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 855:1, s. 1-18
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Journal article (peer-reviewed)abstract
- Combining visual and spectroscopic orbits of binary stars leads to a determination of the full 3D orbit, individual masses, and distance to the system. We present a full analysis of the evolved binary system delta Delphini using astrometric data from the MIRC and PAVO instruments on the CHARA long-baseline interferometer, 97 new spectra from the Fairborn Observatory, and 87 unpublished spectra from the Lick Observatory. We determine the full set of orbital elements for delta Del, along with masses of 1.78 +/- 0.07 M-circle dot and 1.62 +/- 0.07 M-circle dot for each component, and a distance of 63.61 +/- 0.89 pc. These results are important in two contexts: for testing stellar evolution models and for defining the detection capabilities for future planet searches. We find that the evolutionary state of this system is puzzling, as our measured flux ratios, radii, and masses imply a similar to 200 Myr age difference between the components, using standard stellar evolution models. Possible explanations for this age discrepancy include mass transfer scenarios with a now-ejected tertiary companion. For individual measurements taken over a span of two years, we achieve <10 mu as precision on the differential position with 10 minute observations. The high precision of our astrometric orbit suggests that exoplanet detection capabilities are within reach of MIRC at CHARA. We compute exoplanet detection limits around delta Del and conclude that, if this precision is extended to wider systems, we should be able to detect most exoplanets >2M(J) on orbits >0.75 au around individual components of hot binary stars via differential astrometry.
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| 4. |
- Kluska, J., et al.
(author)
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VLTI images of circumbinary disks around evolved stars
- 2020
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11446
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Conference paper (peer-reviewed)abstract
- The new generation of VLTI instruments (GRAVITY, MATISSE) aims to produce routinely interferometric images to uncover the morphological complexity of different objects at high angular resolution. Image reconstruction is, however, not a fully automated process. Here we focus on a specific science case, namely the complex circumbinary environments of a subset of evolved binaries, for which interferometric imaging provides the spatial resolution required to resolve the immediate circumbinary environment. Indeed, many binaries where the main star is in the post-asymptotic giant branch (post-AGB) phase are surrounded by circumbinary disks. Those disks were first inferred from the infrared excess produced by dust. Snapshot interferometric observations in the infrared confirmed disk-like morphology and revealed high spatial complexity of the emission that the use of geometrical models could not recover without being strongly biased. Arguably, the most convincing proof of the disk-like shape of the circumbinary environment came from the first interferometric image of such a system (IRAS08544-4431) using the PIONIER instrument at the VLTI. This image was obtained using the SPARCO image reconstruction approach that enables to subtract a model of a component of the image and reconstruct an image of its environment only. In the case of IRAS08544-4431, the model involved a binary and the image of the remaining signal revealed several unexpected features. Then, a second image revealed a different but also complex circumstellar morphology around HD101584 that was well studied by ALMA. To exploit the VLTI imaging capability to understand these targets, we started a large programme at the VLTI to image post-AGB binary systems using both PIONIER and GRAVITY instruments.
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| 5. |
- Roettenbacher, Rachael M., et al.
(author)
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Contemporaneous Imaging Comparisons of the Spotted Giant sigma Geminorum Using Interferometric, Spectroscopic, and Photometric Data
- 2017
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 849:2
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Journal article (peer-reviewed)abstract
- Nearby active stars with relatively rapid rotation and large starspot structures offer the opportunity to compare interferometric, spectroscopic, and photometric imaging techniques. In this paper, we image a spotted star with three different methods for the first time. The giant primary star of the RS Canum Venaticorum binary sigma. Geminorum (sigma Gem) was imaged for two epochs of interferometric, high-resolution spectroscopic, and photometric observations. The light curves from the reconstructions show good agreement with the observed light curves, supported by the longitudinally consistent spot features on the different maps. However, there is strong disagreement in the spot latitudes across the methods.
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| 6. |
- Roettenbacher, Rachael M., et al.
(author)
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KOI-1003 : A NEW SPOTTED, ECLIPSING RS CVN BINARY IN THE KEPLER FIELD
- 2016
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 832:2
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Journal article (peer-reviewed)abstract
- Using the high-precision photometry from the Kepler space telescope, thousands of stars with stellar and planetary companions have been observed. The characterization of stars with companions is not always straightforward and can be contaminated by systematic and stellar influences on the light curves. Here, through a detailed analysis of starspots and eclipses, we identify KOI-1003 as a new, active RS CVn star-the first identified with data from Kepler. The Kepler light curve of this close binary system exhibits the system's primary transit, secondary eclipse, and starspot evolution of two persistent active longitudes. The near equality of the system's orbital and rotation periods indicates the orbit and primary star's rotation are nearly synchronized (P-orb = 8.360613 +/- 0.000003 days; P-rot similar to 8.23 days). By assuming the secondary star is on the main sequence, we suggest the system consists of a 1.45(-0.19)(+0.11) M-circle dot subgiant primary and a 0.59(-0.04)(+0.03) M-circle dot main-sequence companion. Our work gives a distance of 4400 +/- 600 pc and an age of t = 3.0(+2.0)(-0.5) Gyr, parameters which are discrepant with previous studies that included the star as a member of the open cluster NGC 6791.
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