Nulling Data Reduction and on-Sky Performance of the Large Binocular Telescope Interferometer

Defrère, Denis; Hinz, Philip M.; Mennesson, Bertrand; Hoffmann, W. F.; Millan-Gabet, R.; Skemer, Andrew J.; Bailey, Vanessa P.; Danchi, W. C.; Downey, E.; Durney, Olivier; Grenz, P.; Hill, John M.; McMahon, T. J.; Montoya, Manny; Spalding, Eckhart; Vaz, Amali; Absil, Olivier; Arbo, P.; Bailey, Hop; Brusa, Guido; Bryden, G.; Esposito, Simone; Gáspár, András; Haniff, C.; Kennedy, Grant M.; Leisenring, Jarron; Marion, Lindsay; Nowak, Matthew; Pinna, Enrico; Powell, Keith; Puglisi, Alfio; Rieke, G. H.; Roberge, Aki; Serabyn, Eugene; Sosa, Richard; Stapeldfeldt, K.; Su, K. Y. L.; Weinberger, Alycia J.; Wyatt, M. C.

doi:10.3847/0004-637x/824/2/66

Cited by 83 publications

(76 citation statements)

References 53 publications

(47 reference statements)

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“…2 were photometric, but for specific systems it is possible to go deeper. Indeed, it might be possible to rule out a dust spot scenario using nulling interferometry (LBTI), which can go a few orders of magnitude deeper (Defrère et al 2016). However, LBTI requires bright stars, so this option would only be available for the nearest stars, which is the most interesting since this is where astrometric measurements are most sensitive.…”

Section: Discussionmentioning

confidence: 99%

“…One way to explain this would be to show that the detection of the astrometric effect detected by Pravdo & Shaklan at 550-750 nm is wavelength dependent, for instance, in the far-IR or submillimetric regimes. We recommend observing it with SKA, when built, using astrometry or the Large Binocular Telescope Interferometer (LBTI, Defrère et al 2016) to look for warm dust.…”

Section: Chromaticitymentioning

confidence: 99%

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Effects of disc asymmetries on astrometric measurements

Kral

Kennedy

Souami

2016

A&A

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Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement of the photo-centre owing to inhomogeneities in a dust disc around the parent star. Indeed, theory and observations show that circumstellar discs can present strong asymmetries. We model the pseudo-astrometric signal caused by these inhomogeneities, asking whether a dust clump in a disc can mimic the astrometric signal of an Earth-like planet. We show that these inhomogeneities cannot be neglected when using astrometry to find terrestrial planets. We provide the parameter space for which these inhomogeneities can affect the astrometric signals but still not be detected by mid-IR observations. We find that a small cross section of dust corresponding to a cometary mass object is enough to mimic the astrometric signal of an Earth-like planet. Astrometric observations of protoplanetary discs to search for planets can also be affected by the presence of inhomogeneities. Some further tests are given to confirm whether an observation is a real astrometric signal from a planet or an impostor. Eventually, we also study the case where the cross-section of dust is high enough to provide a detectable IR-excess and to have a measurable photometric displacement by actual instruments such as Gaia, IRAC, or GRAVITY. We suggest a new method, which consists of using astrometry to quantify asymmetries (clumpiness) in inner debris discs that cannot be otherwise resolved.

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Section: Discussionmentioning

confidence: 99%

Section: Chromaticitymentioning

confidence: 99%

Effects of disc asymmetries on astrometric measurements

Kral

Kennedy

Souami

2016

A&A

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“…24 Given the rapid sky variations, this procedure was found to perform better skysubtraction than alternatives such as the subtraction of a single frame from one of the adjacent nods, or the subtraction of an average of a median-combination of a fixed number of frames from both adjacent nods. At this point, the two-dimensional framesS were generated viã…”

Section: The Pipelinementioning

confidence: 99%

Infrared photometry with 'wall-eyed' pointing at the Large Binocular Telescope

et al. 2016

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The brightness and variability of the atmosphere in the thermal infrared poses obstacles to precision photometry measurements. The need to remove atmospheric effects calls for the use of a comparison star, but it is usually impossible to fit both science and comparison targets on current long-wavelength (>2 µm) detectors. We present a new pointing mode at the Large Binocular Telescope, which has twin 8.4-m primary mirrors that can be pointed up to ∼2 arcminutes apart and allow the placement of both targets on a small-field infrared detector. We present an observation of the primary transit of an exoplanet in front of its host star, and use it to provide preliminary constraints on the attainable photometric precision.

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“…In a recent paper by Defrère et al [39], the LBTI team reported progress on the LBTI HOSTS program as of the end of the commissioning phase in the spring of 2015. This paper discussed the theory of operation of the LBTI as a nulling interferometer, data reduction methods, and on sky performance.…”

Section: Nulling Data Reduction and On-sky Performance Of Lbtimentioning

confidence: 99%

Enabling the direct detection of earth-sized exoplanets with the LBTI HOSTS project: a progress report

et al. 2016

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NASA has funded a project called the Hunt for Observable Signatures of Terrestrial Systems (HOSTS) to survey nearby solar type stars to determine the amount of warm zodiacal dust in their habitable zones. The goal is not only to determine the luminosity distribution function but also to know which individual stars have the least amount of zodiacal dust. It is important to have this information for future missions that directly image exoplanets as this dust is the main source of astrophysical noise for them. The HOSTS project utilizes the Large Binocular Telescope Interferometer (LBTI), which consists of two 8.4-m apertures separated by a 14.4-m baseline on Mt. Graham, Arizona. The LBTI operates in a nulling mode in the mid-infrared spectral window (8-13 µm), in which light from the two telescopes is coherently combined with a 180 degree phase shift between them, producing a dark fringe at the location of the target star. In doing so the starlight is greatly reduced, increasing the contrast, analogous to a coronagraph operating at shorter wavelengths. The LBTI is a unique instrument, having only three warm reflections before the starlight reaches cold mirrors, giving it the best photometric sensitivity of any interferometer operating in the mid-infrared. It also has a superb Adaptive Optics (AO) system giving it Strehl ratios greater than 98% at 10 µm. In 2014 into early 2015 LBTI was undergoing commissioning. The HOSTS project team passed its Operational Readiness Review (ORR) in April 2015. The team recently published papers on the target sample, modeling of the nulled disk images, and initial results such as the detection of warm dust around η Corvi. Recently a paper was published on the data pipeline and on-sky performance. An additional paper is in preparation on β Leo. We will discuss the scientific and programmatic context for the LBTI project, and we will report recent progress, new results, and plans for the science verification phase that started in February 2016, and for the survey.

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Nulling Data Reduction and on-Sky Performance of the Large Binocular Telescope Interferometer

Cited by 83 publications

References 53 publications

Effects of disc asymmetries on astrometric measurements

Effects of disc asymmetries on astrometric measurements

Infrared photometry with 'wall-eyed' pointing at the Large Binocular Telescope

Enabling the direct detection of earth-sized exoplanets with the LBTI HOSTS project: a progress report

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