Photometric and Astrometric Calibration of the JWST Instrument Complement

In preparation for James Webb Space Telescope (JWST), a set of cross calibration programs with HST and Spitzer for suitable primary photometric standards and astrometric fields were developed. NICMOS/HST and IRAC/Spitzer photometry observations of new solar analog standards in NGC 6791 and Melotte 66 were executed. These new photometric standards will provide ~ 5% photometric precision at V~19 from the near-IR to the mid-IR wavelength range for efficient on-orbit calibration and measuring of photometric stability of the JWST complement. For the astrometric calibration, a field in the LMC has been selected. This field falls within the JWST continuous viewing zone, within 5 degrees from the ecliptic poles, and has the stellar density necessary to achieve accuracies better than 1 mas with HST/ACS. These independent observations will play a key role in meeting the mission requirements and will allow a fast commissioning of the observatory.Comment: 9 pages, 3 figures; to appear in The Future of Photometric, spectrophotometric, and Polarimetric Standardization, ed. C. Sterken, AS

On the deduction of galaxy abundances with evolutionary neural networks

A growing number of indicators are now being used with some confidence to measure the metallicity(Z) of photoionisation regions in planetary nebulae, galactic HII regions(GHIIRs), extra-galactic HII regions(EGHIIRs) and HII galaxies(HIIGs). However, a universal indicator valid also at high metallicities has yet to be found. Here, we report on a new artificial intelligence-based approach to determine metallicity indicators that shows promise for the provision of improved empirical fits. The method hinges on the application of an evolutionary neural network to observational emission line data. The network's DNA, encoded in its architecture, weights and neuron transfer functions, is evolved using a genetic algorithm. Furthermore, selection, operating on a set of 10 distinct neuron transfer functions, means that the empirical relation encoded in the network solution architecture is in functional rather than numerical form. Thus the network solutions provide an equation for the metallicity in terms of line ratios without a priori assumptions. Tapping into the mathematical power offered by this approach, we applied the network to detailed observations of both nebula and auroral emission lines in the optical for a sample of 96 HII-type regions and we were able to obtain an empirical relation between Z and S23 with a dispersion of only 0.16 dex. We show how the method can be used to identify new diagnostics as well as the nonlinear relationship supposed to exist between the metallicity Z, ionisation parameter U and effective (or equivalent) temperature T*.Comment: Accepted for publication in PASP. 6 pages, 2 figure

An empirical calibration of nebular abundances based on the sulphur emission lines

We present an empirical calibration of nebular abundances based on the strong emission lines of [SII] and [SIII] in the red part of the spectrum through the definition of a sulphur abundance parameter S23. This calibration presents two important advantages against the commonly used one based on the optical oxygen lines: it remains single-valued up to abundances close to solar and is rather independent of the degree of ionization of the nebula.Comment: 10 pages, 8 figures. Accepted for publication in MNRA

A grid of chemical evolution models along the Hubble Sequence

We have computed a grid of multiphase chemical evolution models whose results are valid for any spiral galaxy, using as input the maximum rotation velocity and the morphological type or index T.Comment: 2 pag., contribution to the conference Cosmic Evolution (Paris, Nov. 2000

Human-display interaction technology: Emerging remote interfaces for pervasive display environments

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.We're living in a world where information processing isn't confined to desktop computers - it's being integrated into everyday objects and activities. Pervasive computation is human centered: it permeates our physical world, helping us achieve goals and fulfill our needs with minimum effort by exploiting natural interaction styles. Remote interaction with screen displays requires a sensor-based, multimodal, touchless approach. For example, by processing user hand gestures, this paradigm removes constraints requiring physical contact and permits natural interaction with tangible digital information. Such touchless interaction can be multimodal, exploiting the visual, auditory, and olfactory senses.Ministerio de Educación y Ciencia and Amper Sistemas, SA

The continuous star formation history of a giant HII region in M101

We present results about the star formation process in the giant HII region NGC 5471 in the outskirts of M101. From resolved HST/WPFC2 photometry we find that star formation has been going for the last 70 Myr. We further compare previous results from integrated infrared-optical photometry with the stellar resolved CMD and we discuss the star formation properties of this region and its individual knots, as well as characterizing the different stellar content. This result has very important consequences in our understanding of the burst versus continuous star formation activity in spiral galaxies.Comment: 2 pages, 2 figures. Proceeding of the conference From Stars to Galaxies: Building the pieces to build up the Universe (Venice, Italy