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Register a new userMulti-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR1415
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We employ the recently installed near infrared Multi-Conjugate Adaptive optics demonstrator (MAD) to determine basic properties of a newly identified, old and distant, Galactic open cluster (FSR1415). The MAD facility remarkably approaches the diffraction limit, reaching a resolution of 0.07 arcsec (in K), that is also uniform in a field of ~1.8 arcmin in diameter. The MAD facility provides photometry that is 50% complete at K~19. This corresponds to about ~2.5 mag below the cluster main sequence turn-off. This high quality data set allows us to derive an accurate heliocentric distance of ~8.6 kpc, a metallicity close to solar, and an age of ~2.5 Gyr. On the other hand, the deepness of the data allow us to reconstruct (completeness-corrected) mass functions indicating a relatively massive cluster, with a flat core MF. The VLT/MAD capabilities will therefore provide fundamental data in identifying/analyzing other faint and distant open clusters in the Galaxy III and IV quadrants.
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The globular cluster HP1 is projected on the bulge, very close to the Galactic center. The Multi-Conjugate Adaptive Optics (MCAO) Demonstrator (MAD) at the Very Large Telescope (VLT) allowed to acquire high resolution deep images that, combined with first epoch New Technology Telescope (NTT) data, enabled to derive accurate proper motions. The cluster and bulge field stellar contents were disentangled by means of this process, and produced unprecedented definition in the color-magnitude diagrams for this cluster. The metallicity of [Fe/H] ~ -1.0 from previous spectroscopic analysis is confirmed, which together with an extended blue horizontal branch, imply an age older than the halo average. Orbit reconstruction results suggest that HP1 is spatially confined within the bulge.
We present the Phase A Science Case for the Multi-conjugate Adaptive-optics Visible Imager-Spectrograph (MAVIS), planned for the Adaptive Optics Facility (AOF) of the Very Large Telescope (VLT). MAVIS is a general-purpose instrument for exploiting the highest possible angular resolution of any single optical telescope available in the next decade, either on Earth or in space, and with sensitivity comparable to (or better than) larger aperture facilities. MAVIS uses two deformable mirrors in addition to the deformable secondary mirror of the AOF, providing a mean V-band Strehl ratio of >10% (goal >15%) across a relatively large (30 arc second) science field. This equates to a resolution of <20mas at 550nm - comparable to the K-band diffraction limit of the next generation of extremely large telescopes, making MAVIS a genuine optical counterpart to future IR-optimised facilities like JWST and the ELT. Moreover, MAVIS will have unprecedented sky coverage for a high-order AO system, accessing at least 50% of the sky at the Galactic Pole, making MAVIS a truly general purpose facility instrument. As such, MAVIS will have both a Nyquist-sampled imager (30x30 arcsec field), and a powerful integral field spectrograph with multiple spatial and spectral modes spanning 370-1000nm. This science case presents a distilled set of thematically linked science cases drawn from the MAVIS White Papers (www.mavis-ao.org/whitepapers), selected to illustrate the driving requirements of the instrument resulting from the recent MAVIS Phase A study.
We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the field of view. Finally, we outline the role that large samples of stellar standards plays in providing a detailed description of the MCAO performance and in precise and accurate colour{magnitude diagrams.
The high angular resolution and dynamic range achieved by the NACO adaptive optics system on the VLT is an excellent tool to study the morphology of Planetary Nebulae (PNe). We observed four stars in different evolutionary stages from the AGB to the PNe phase. The images of the inner parts of the PN Hen 2-113 reveal the presence of a dusty torus tilted with respect to all the other structures of the nebula and the present of hot dust close to the hot central star. The NACO observations of Roberts 22 reveal an amazingly complex nebular morphology with a S-shape that can be interpreted in terms of the warped disc scenario of Icke (2003). Combined NACO and MIDI (the VLTI mid-infrared interferometer) observations of the nebula OH 231.8+4.2 have enabled us to resolve a very compact (diameter of 30-40 mas, corresponding to 40-50 a.u.) dusty structure in the core of the nebula. Finally, recent observations of the AGB star V Hydrae show that this star present a departure from spherical symmetry in its inner shell and is probably on its way to become an asymmetrical planetary nebula. These observations show that NACO is a great instrument for the discovery and study of small structures in circumstellar envelopes and PNe and a good complement to interferometric devices.
MAORY is the adaptive optics module for ELT providing two gravity invariant ports with the same optical quality for two different client instruments. It enable high angular resolution observations in the near infrared over a large field of view (~1 arcmin2 ) by real time compensation of the wavefront distortions due to atmospheric turbulence. Wavefront sensing is performed by laser and natural guide stars while the wavefront sensor compensation is performed by an adaptive deformable mirror in MAORY which works together with the telescopes adaptive and tip tilt mirrors M4 and M5 respectively.
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