Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory

Brummelaar, T. ten; Mason, Brian D.; McAlister, Harold A.; Roberts, Lewis C.; Turner, N.; Hartkopf, William I.; Bagnuolo, W. G.

doi:10.1086/301338

Cited by 76 publications

(69 citation statements)

References 31 publications

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“…This method is similar to what the routine fitstars, presented in ten Brummelaar et al (1996Brummelaar et al ( , 2000, does to calculate the photometry of binaries. In the following paragraphs we describe this method in more detail.…”

Section: Photometry With Irdismentioning

confidence: 99%

Performance of the VLT Planet Finder SPHERE

Zurlo

Vigan

Mesa

et al. 2014

A&A

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Context. The new planet finder for the Very Large Telescope (VLT), the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), just had its first light in Paranal. A dedicated instrument for the direct detection of planets, SPHERE, is composed of a polametric camera in visible light, the Zurich IMager POLarimeter (ZIMPOL), and two near-infrared sub-systems: the Infra-Red Dual-beam Imager and Spectrograph (IRDIS), a multi-purpose camera for imaging, polarimetry, and long-slit spectroscopy, and the integral field spectrograph (IFS), an integral field spectrograph. Aims. We present the results obtained from the analysis of data taken during the laboratory integration and validation phase, after the injection of synthetic planets. Since no continuous field rotation could be performed in the laboratory, this analysis presents results obtained using reduction techniques that do not use the angular differential imaging (ADI) technique. Methods. To perform the simulations, we used the instrumental point spread function (PSF) and model spectra of L and T-type objects scaled in contrast with respect to the host star. We evaluated the expected error in astrometry and photometry as a function of the signal to noise of companions, after spectral differential imaging (SDI) reduction for IRDIS and spectral deconvolution (SD) or principal component analysis (PCA) data reductions for IFS. Results. We deduced from our analysis, for example, that β Picb, a 12 Myr old planet of ∼10 M Jup and semi-major axis of 9-10 AU, would be detected with IRDIS with a photometric error of 0.16 mag and with a relative astrometric position error of 1.1 mas. With IFS, we could retrieve a spectrum with error bars of about 0.15 mag on each channel and astrometric relative position error of 0.6 mas. For a fainter object such as HR 8799d, a 13 M Jup planet at a distance of 27 AU, IRDIS could obtain a relative astrometric error of 3 mas.

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Section: Photometry With Irdismentioning

confidence: 99%

Performance of the VLT Planet Finder SPHERE

Zurlo

Vigan

Mesa

et al. 2014

A&A

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“…After reducing each image, we measured the astrometry and photometry using the fitstars algorithm on each image (ten Brummelaar et al 1996Brummelaar et al , 2000. Photometric error bars were set equal to the standard deviation of the measurements from all the images.…”

Section: Keck II Observationsmentioning

confidence: 99%

KNOW THE STAR, KNOW THE PLANET. IV. A STELLAR COMPANION TO THE HOST STAR OF THE ECCENTRIC EXOPLANET HD 8673b

Roberts

Mason

Neyman

et al. 2015

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HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e = 0.723). Based on two epochs of speckle interferometry a previous publication identified a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m Advanced Electro-Optical System telescope, and the 1.5 m Palomar telescope in a variety of filters with the aim of confirming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of filters. The measured differential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M  . The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to a semimajor axis of 35-60 AU, an eccentricity ⩽0.5, and an inclination of 75°-85°. The stellar companion has likely strongly influenced the orbit of the exoplanet and quite possibly explains its high eccentricity.

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“…A recent review of modern approaches to AO photometry by Burke et al (2009) demonstrated that methods utilizing static, deterministic PSF should not be dismissed against more modern algorithms like iterative blind deconvolution (ten Brummelaar et al 2000). Therefore, we set out to test whether a modern implementation of the Richardson-Lucy-type deconvolution conserves the flux when given a mismatched AO PSF.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Differential Photometry in Adaptive Optics Observations with a Wavelet-based Maximum Likelihood Estimator

Baena-Gallé

Gładysz

2011

Publications of the Astronomical Society of the Pacific

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ABSTRACT. We propose to use the Bayesian framework and the wavelet transform (WT) to estimate differential photometry in binary systems imaged with adaptive optics (AO). We challenge the notion that RichardsonLucy-type algorithms are not suitable to AO observations because of the mismatch between the target's and reference star's point-spread functions (PSFs). Using real data obtained with the Lick Observatory AO system on the 3 m Shane telescope, we first obtain a deconvolved image by means of the Adaptive Wavelets Maximum Likelihood Estimator (AWMLE) approach. The algorithm reconstructs an image that maximizes the compound Poisson and Gaussian likelihood of the data. It also performs wavelet decomposition, which helps to distinguish signal from noise, and therefore it aides the stopping rule. We test photometric precision of that approach versus PSF-fitting with the StarFinder package for companions located within the halo created by the bright star. Simultaneously, we test the susceptibility of both approaches to error in the reference PSF, as quantified by the difference in the Strehl ratio between the science and calibration PSFs. We show that AWMLE is capable of producing better results than PSF-fitting. More importantly, we have developed a methodology for testing photometric codes for AO observations.

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Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory

Cited by 76 publications

References 31 publications

Performance of the VLT Planet Finder SPHERE

Performance of the VLT Planet Finder SPHERE

KNOW THE STAR, KNOW THE PLANET. IV. A STELLAR COMPANION TO THE HOST STAR OF THE ECCENTRIC EXOPLANET HD 8673b

Estimation of Differential Photometry in Adaptive Optics Observations with a Wavelet-based Maximum Likelihood Estimator

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