MAD about the Large Magellanic Cloud

Fiorentino, G.; Tolstoy, Eline; Diolaiti, Emiliano; Valenti, E.; Cignoni, M.; Mackey, A. D.

doi:10.1051/0004-6361/201016094

Cited by 19 publications

(11 citation statements)

References 36 publications

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“…Multiple deformable mirrors, optically conjugated to different altitudes, apply the correction to the layers of turbulence associated to those heights. While an MCAO system can work using only NGSs, such as the MCAO demonstrator MAD on VLT (Marchetti et al 2003;Ferraro et al 2009;Moretti et al 2009;Bono et al 2010;Fiorentino et al 2011), the use of LGSs is advantageous because it alleviates the requirements for an asterism of bright stars close to the scientific target, thus increasing significantly the sky coverage.…”

Section: Introductionmentioning

confidence: 99%

Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics

Turri

McConnachie

Stetson

et al. 2017

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We present a detailed discussion of how to obtain precise stellar photometry in crowded fields using images from multi-conjugate adaptive optics (MCAO) systems, with the intent of informing the scientific development of this key technology for the Extremely Large Telescopes. We use deep J and K s exposures of NGC 1851 taken with the Gemini Multi-Conjugate Adaptive Optics System (GeMS) on Gemini South to quantify the performance of the instrument and to develop an optimal strategy for stellar photometry using PSF-fitting techniques. We judge the success of the various methods we employ by using science-based metrics, particularly the width of the main sequence turn-off region. We also compare the GeMS photometry with the exquisite HST data in the visible of the same target. We show that the PSF produced by GeMS possesses significant spatial and temporal variability that must be accounted for during the analysis. We show that the majority of the variation of the PSF occurs within the "control radius" of the MCAO system and that the best photometry is obtained when the PSF radius is chosen to closely match this spatial scale. We identify photometric calibration as a critical issue for next generation MCAO systems such as those on TMT and E-ELT. Our final CMDs reach K s ∼22-below the main sequence knee-making it one of the deepest for a globular cluster available from the ground. Theoretical isochrones are in remarkable agreement with the stellar locus in our data from below the main sequence knee to the upper red giant branch.

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Section: Introductionmentioning

confidence: 99%

Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics

Turri

McConnachie

Stetson

et al. 2017

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“…This technology allows ground-based observations reach the diffraction limit over a modest field of view (∼ 1×1 ). High-resolution NIR images of GCs can have a relevant impact on current astrophysical problems as soundly demonstrated by MAD (Multi-Conjugated Adaptive Optics Demonstrator, Marchetti et al 2003) the pilot VLT instrument built to test on the sky the feasibility of a multi-conjugated AO (MCAO) systems (Ferraro et al 2009;Bono et al 2009;Moretti et al 2009;Fiorentino et al 2011). The robustness of the current MCAO systems has been further supported by GeMS/GSAOI available at the GEMINI-South telescope (Neichel et al 2014b,a;Rigaut et al 2014).…”

Section: Introductionmentioning

confidence: 99%

The Absolute Age of the Globular Cluster M15 Using Near-Infrared Adaptive Optics Images From Pisces/LBT

Monelli

Testa

Bono

et al. 2015

ApJ

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We present deep near-infrared (NIR) J, K s photometry of the old, metal-poor Galactic globular cluster M 15 obtained with images collected with the LUCI1 and PISCES cameras available at the Large Binocular Telescope (LBT). We show how the use of First Light Adaptive Optics system coupled with the (FLAO) PISCES camera allows us to improve the limiting magnitude by ∼2 mag in K s . By analyzing archival HST data, we demonstrate that the quality of the LBT/PISCES color magnitude diagram is fully comparable with analogous space-based data. The smaller field of view is balanced by the shorter exposure time required to reach a similar photometric limit. We investigated the absolute age of M 15 by means of two methods: i) by determining the age from the position of the main sequence turn-off; and ii) by the magnitude difference between the MSTO and the well-defined knee detected along the faint portion of the MS. We derive consistent values of the absolute age of M 15, that is 12.9±2.6 Gyr and 13.3±1.1 Gyr, respectively.

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“…The distance modulus to the LMC has been extensively discussed in the literature, since this galaxy is the cornerstone of the distance scale. We adopt here μ 0 = 18.50 mag, as given by a recent estimate using Red Clump stars observed in optical and near-IR (Fiorentino et al 2011). This agrees with many of the measurements derived by independent methods, including classical Cepheids (Bono et al 2002), RR Lyrae stars (Catelan & Cortés 2008), planetary nebulae luminosity function (Reid & Parker 2010), the red clump, and the tip of the red giant branch (Romaniello et al 2000).…”

Section: Comparison With Theoretical Predictionsmentioning

confidence: 99%

Anomalous Cepheids in the Large Magellanic Cloud

Fiorentino

Monelli

2012

A&A

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Context. The properties of variable stars can give independent constraints on the star formation history of the host galaxy, by determining the age and metallicity of the parent population. Aims. We investigate the pulsation properties of 84 Anomalous Cepheids (ACs) detected by the OGLE-III survey in the Large Magellanic Cloud (LMC), in order to understand the formation mechanism and the characteristics of the parent population they came from. Methods. We used an updated theoretical pulsation scenario to derive the mass and the pulsation mode of each AC in the sample. We also used a Kolmogorov-Smirnov test to analyze the spatial distribution of the ACs, in comparison with that of other groups of variable stars, and connect their properties with the star formation history of the LMC. Results. We find that the mean mass of ACs is 1.2 ± 0.2 M . We show that ACs do not follow the same spatial distribution of classical Cepheids. This and the difference in their period-luminosity relations further support the hypothesis that ACs are not the extension to low luminosity of classical Cepheids. The spatial distribution of ACs is also different from that of bona-fide tracers of the old population, such as RR Lyrae stars and population II Cepheids. We therefore suggest that the majority of ACs in the LMC are made of intermediate-age (1-6 Gyr), metal-poor single stars. Finally, we investigate the relation between the frequency of ACs and the luminosity of the host galaxy, disclosing that purely old systems follow a very tight relation and that galaxies with strong intermediate-age and young star formation tend to have an excess of ACs, in agreement with their hosting ACs formed via both single and binary star channels.

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MAD about the Large Magellanic Cloud

Cited by 19 publications

References 36 publications

Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics

Optimal Stellar Photometry for Multi-conjugate Adaptive Optics Systems Using Science-based Metrics

The Absolute Age of the Globular Cluster M15 Using Near-Infrared Adaptive Optics Images From Pisces/LBT

Anomalous Cepheids in the Large Magellanic Cloud

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