Here you may find information on the fellows of the PhD::SPACE Program that have selected a topic on the thematic line on Space and Ground Systems and Technologies.
2019/B024 Fellow: Cédric P. Pereira (ongoing)
Advisors: Manuel Adler Abreu (IA-U.Lisboa & FCUL), Alexandre P. Cabral (IA-U.Lisboa & FCUL)
PhD Topic (2019/506): Stabilization of calibration light sources for High Accuracy Photometry Instruments
Transit spectroscopy and multi-band photometry has been so far conducted using general-purpose, space-based instruments. These measurements however suffer from a high level of systematic error due to issues such as pointing jitter, thermal and opto-mechanical stability, wavelength and photometric calibration, and detector stability. Testing and calibration of high precision photometers for the detection of planetary transits requires a light source which photometric stability must be better than the goal stability of the photometer to be tested.
In case test, integration and calibration of these sensors, it will be required highly radiometrically stable light sources, both in flux and spectra.
The proposed project aims to research and develop a device that senses the light source fluctuations and modulates the beam, both in flux and in spectra, to produce a sufficiently stable source, a truly impressive challenge when stabilization levels of few ppm are required over long periods of observation.
Starting date: 2019/10/01
2017/B020 Fellow: Bachar Wehbe (finish)
Advisors: Alexandre P. Cabral (IA-U.Lisboa & FCUL), Gerardo Ávila Soberanes (ESO)
PhD Topic (2017/504c): Atmospheric Dispersion Correction for High Resolution Astronomical Instruments
This proposal is focused on the development of Atmospheric Dispersion Correctors for current astronomical instruments where the recent developments in the field of adaptive optics systems, improving considerably the performances of telescope resolution, and the arrival of large telescopes with diameters up to 40 m, reinforce the need to revisit the way differential atmospheric dispersion is corrected and how it influences the performances of high resolution spectrographs.
The work for this proposal will cover both the Study of the atmospheric dispersion phenomena and how it influences astronomical observations and the analysis and development of Atmospheric Dispersion Correctors (ADC). All will be supported by the work on three case studies, each one on a different astronomical instrument: the already installed Espresso ADC, the current NIRPS ADC and the future E-ELT HIRES ADC(s)
University: Porto & Lisboa
Starting date: 2017/10/01
2014/B005 Fellow: Tiago E. C. Magalhães (completed)
Advisors: José Manuel N. V. Rebordão (IA FCUL)
PhD Topic (2014/502): Impact of the Wolf effect in ESPRESSO: Effects of propagation of partially coherent light on the very high resolution spectra of stars
ESPRESSO – (Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations), is a super-stable optical high resolution spectrograph for the combined Coude’ focus of the VLT. It can be operated by either one of the UTs or collecting the light from up to 4 UTs simultaneously. In this last configuration, light from 4 UT’s is incoherently combined, in order to increase the flux delivered to the spectrograph. One of the most important goals of ESPRESSO is the detection of exo-planets through spectral changes induced by their orbiting velocity.
The Wolf Effect (or Wolf shift) – is a frequency shift in the electromagnetic spectrum, that has been described as a new redshift mechanism. The phenomenon occurs in several closely related phenomena in radiation physics, with analogous effects occurring in the scattering of light. It was first predicted by Emil Wolf in 1987 and subsequently confirmed in the laboratory by Dean Faklis and George Morris in 1988.
Wolf and others have suggested that the Wolf effect as a possible non-cosmological redshift and also relevant to gravitational lensing. In optics, two non-Lambertian sources that emit beamed energy can interact in a way that causes a shift in the spectral lines. It is analogous to a pair of tuning forks with similar frequencies (pitches), connected together mechanically with a sounding board; there is a strong coupling that results in the resonant frequencies getting “dragged down” in pitch. The Wolf Effect requires that the waves from the sources are partially coherent.
This PhD proposal will address to what extent the Wolf effect should or should not be totally discarded in ESPRESSO, in spite of the split of light from a star into 4 telescopes, with the potential to create a kind of cross-correlation equivalent to source partial coherence or other forms of source correlations required by the Wolf Effect.
Starting date: 2015/03/01
2014/B001 Fellow: Jason J. Neal (completed)
PhD Topic (2014/501): Towards exoplanetary atmospheres: new data reduction methods for the nIR
The search for extrasolar planets has as one of its crowns the study of exo-atmospheres. This goal has been shaping Science and scientific instrumentation for the last decade. In this project we provide a gradual approach to developing and perfecting of methodologies required for the detection and characterization of exo-atmospheres.
Building up on current in-house knowledge, we propose to develop the methodologies required for the extraction of the maximum of information, and in particular the minute signals of exoplanets from nIR spectra. The risk of this ambitions program will be minimized by a thorough and gradual pathway to this objective. The intermediary tasks and objectives have been laid out and a significant amount of observational data has already been acquired and is fully available to be explored from day one.
The expertise gained through this project will give the PhD the ability to efficiently reduce and explore nIR spectroscopic data, an emerging field in astronomy, in particular in the domain of extrasolar planets. The results of this project will be used for the science verification of two upgraded infrared instruments: CRIRES+ and VISIR (both at the VLT-ESO).
Starting date: 2014/10/01