HARMONI is a first-light visible and near-IR integral field spectrograph of ESO’s Extremely Large Telescope (ELT) which will sit on top of Cerro Armazones, Chile. A Single Conjugate Adaptive Optics (SCAO) subsystem will provide diffraction-limited spectro-images in a Nyquist-sampled 0.61 x 0.86 arcsec field of view, with a R=3000-20000 spectral resolution. Inside the instrument, a High Contrast Module (HCM) could give HARMONI the ability to spectrally characterize young giant exoplanets (and disks) with flux ratio down to 10−6 as close as 100-200mas from their star. This would be achieved with an apodized pupil coronagraph to attenuate the diffracted light of the star and limit the dynamic range on the detector, and an internal ZELDA wavefront sensor to calibrate non-common path aberrations, assuming that the surface quality of the relay optics of HARMONI satisfy specific requirements. This communication presents (a) the system analysis that was conducted to converge towards these requirement, and the proposed HCM design, (b) an end-to-end simulation tool that has been built to produce realistic datacubes of hour-long observations, and (c) the estimated performance of the HCM, which has been derived by applying differential imaging techniques on the simulated data.
Over the past few years, several large ground-based facilities have enhanced their exoplanet direct imaging capabilities to observe planetary companions and debris disks around nearby stars. The Gran Telescopio Canarias (GTC) will soon have its first high-contrast capabilities with FRIDA. This near-infrared imager and integral field spectrograph will operate with GTCAO, the adaptive optics system of the telescope, to cover a broad range of astrophysical topics. In 2008, we performed preliminary studies to design a high-contrast mode for FRIDA. In this communication, we revisit these studies by investigating different options in coronagraphy to define a final high-contrast baseline for this instrument. Acknowledging the mechanical constraints of FRIDA and the GTCAO performance for high-contrast observations (60% Strehl ratio in K-band), we evaluate different options such as standalone pupil apodizations and classical Lyot coronagraphs to achieve a 10−5 contrast at 200-300 mas from an observed star over wide spectral bands. We then derive the adopted solutions for design and manufacturing of the prototypes. Finally, we discuss possible combinations of high-dispersion spectroscopy and high-contrast imaging for advanced exoplanet observations with this instrument.
HARMONI is a first-light visible and near-IR integral field spectrograph of ESO’s Extremely Large Telescope (ELT) which will sit on top of Cerro Armazones, Chile. A Single Conjugate Adaptive Optics (SCAO) sub-system will provide diffraction-limited spectral images in a Nyquist-sampled 0.61 × 0.86 arcsec field of view, with a R=3000-20000 spectral resolution. Inside the instrument, a High Contrast Module (HCM) will add an essential high-contrast imaging capability for HARMONI to spectrally characterize young giant exoplanets and disks with flux ratio down to 1e-6 at 0.1-0.2” from their star. The HCM uses an apodized pupil coronagraph to lower the intensity of the diffracted starlight and limit the dynamic range on the detector, and an internal wavefront sensor to calibrate non-common path aberrations. This communication first summarizes the basic technical requirements of the HCM, then describes its optical and mechanical designs, and presents expected performance in terms of achievable contrast, image quality and throughput. Elements of the development and test program are also given.
In Spring 2013, the LEECH (LBTI Exozodi Exoplanet Common Hunt) survey began its ~130-night campaign from the Large Binocular Telescope (LBT) atop Mt Graham, Arizona. This survey benefits from the many technological achievements of the LBT, including two 8.4-meter mirrors on a single fixed mount, dual adaptive secondary mirrors for high Strehl performance, and a cold beam combiner to dramatically reduce the telescope’s overall background emissivity. LEECH neatly complements other high-contrast planet imaging efforts by observing stars at L’ (3.8 μm), as opposed to the shorter wavelength near-infrared bands (1-2.4 μm) of other surveys. This portion of the spectrum offers deep mass sensitivity, especially around nearby adolescent (~0.1-1 Gyr) stars. LEECH’s contrast is competitive with other extreme adaptive optics systems, while providing an alternative survey strategy. Additionally, LEECH is characterizing known exoplanetary systems with observations from 3-5μm in preparation for JWST.
Z CMa is a young binary system consisting of an Herbig primary and a FU Ori companion. Both components
seem to be surrounded by active accretion disks and a jet was associated to the Herbig B0. In Nov. 2008,
K. Grankin discovered that Z CMa was exhibiting an outburst with an amplitude larger than any photometric
variations recorded in the last 25 years. To study the innermost regions in which the outburst occurs and
understand its origin, we have observed both binary components with AMBER/VLTI across the Br
line in Dec. 2009 in medium and high spectral resolution modes. Our observations show that the Herbig Be,
responsible for the increase of luminosity, also produces a strong Br
emission, and they allow us to disentangle
from various origins by locating the emission at each velocities through the line. Considering a model of a
Keplerian disk alone fails at reproducing the asymmetric spectro-astrometric measurements, suggesting a major
contribution from an outflow.