Speckle temporal stability in XAO coronagraphic images II. Refine model for quasi-static speckle temporal evolution for VLT/SPHERE

Abstract

Observing sequences have shown that the major noise source limitation in high-contrast imaging is due to the presence of quasi-static speckles. The timescale on which quasi-static speckles evolve, is determined by various factors, among others mechanical or thermal deformations. Understanding of these time-variable instrumental speckles, and especially their interaction with other aberrations, referred to as the pinning effect, is paramount for the search of faint stellar companions. The temporal evolution of quasi-static speckles is for instance required for a quantification of the gain expected when using angular differential imaging (ADI), and to determine the interval on which speckle nulling techniques must be carried out. Following an early analysis of a time series of adaptively corrected, coronagraphic images obtained in a laboratory condition with the High-Order Test bench (HOT) at ESO Headquarters, we confirm our results with new measurements carried out with the SPHERE instrument during its final test phase in Europe. The analysis of the residual speckle pattern in both direct and differential coronagraphic images enables the characterization of the temporal stability of quasi-static speckles. Data were obtained in a thermally actively controlled environment reproducing realistic conditions encountered at the telescope. The temporal evolution of the quasi-static wavefront error exhibits linear power law, which can be used to model quasi-static speckle evolution in the context of forthcoming high-contrast imaging instruments, with implications for instrumentation (design, observing strategies, data reduction). Such a model can be used for instance to derive the timescale on which non-common path aberrations must be sensed and corrected. We found in our data that quasi-static wavefront error increases with ~0.7 angstrom per minute.

A&A accepted

References in corpus (4)

• A New High Contrast Imaging Program at Palomar Observatory
• Speckle noise and dynamic range in coronagraphic images
• Temporal Evolution of Coronagraphic Dynamic Range, and Constraints on Companions to Vega
• Speckle Temporal Stability in eXtreme Adaptive Optics Coronagraphic Images

Cited by in corpus (26)

• Performance of the VLT Planet Finder SPHERE II. Data analysis and Results for IFS in laboratory
• Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor. II. Concept validation with ZELDA on VLT/SPHERE
• Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor. III. On-sky validation in VLT/SPHERE
• Focal-plane wavefront sensing with photonic lanterns I: theoretical framework
• Focal-plane wavefront sensing with the vector Apodizing Phase Plate
• On-sky verification of Fast and Furious focal-plane wavefront sensing: Moving forward toward controlling the island effect at Subaru/SCExAO
• Compensation of high-order quasi-static aberrations on SPHERE with the coronagraphic phase diversity (COFFEE)
• Imaging exoplanets with coronagraphic instruments
• K-Stacker: Keplerian image recombination for the direct detection of exoplanets
• Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor. IV. Temporal stability of non-common path aberrations in VLT/SPHERE
• Active minimization of non-common path aberrations in long-exposure imaging of exoplanetary systems
• High-contrast observations of brown dwarf companion HR 2562 B with the vector Apodizing Phase Plate coronagraph
• Millisecond Exoplanet Imaging, I: Method and Simulation Results
• Coronagraphic phase diversity through residual turbulence: performance study and experimental validation
• Speckle lifetime in XAO coronagraphic images: temporal evolution of SPHERE coronagraphic images
• The spectrally modulated self-coherent camera (SM-SCC): Increasing throughput for focal-plane wavefront sensing
• First on-sky demonstration of spatial Linear Dark Field Control with the vector-Apodizing Phase Plate at Subaru/SCExAO
• Empirical Contrast Model for High-Contrast Imaging -- A VLT/SPHERE Case Study
• The polarization-encoded self-coherent camera
• A Statistical Framework for the Utilization of Simultaneous Pupil Plane and Focal Plane Telemetry for Exoplanet Imaging, Part I: Accounting for Aberrations in Multiple Planes
• Simultaneous ultra-high contrast imaging and determination of time-dependent, non-common path aberrations in the presence of detector noise
• Vector speckle grid: instantaneous incoherent speckle grid for high-precision astrometry and photometry in high-contrast imaging
• Applying a temporal systematics model to vector Apodizing Phase Plate coronagraphic data: TRAP4vAPP
• Recurrence quantification analysis as a post-processing technique in adaptive optics high-contrast imaging
• Chasing the storm: Investigating the application of high-contrast imaging techniques in producing precise exoplanet light curves
• A Multiband Study of the HR 4796A Disk in the Optical Using MagAO-X