Here you may find information on the fellows of the PhD::SPACE Program that have selected a topic on the thematic line on Towards the detection and characterization of other Earths.
2019/B022 Fellow: Tomás A. Silva (ongoing)
Advisors: Olivier Demangeon (IA-U.Porto), Nuno C. Santos (IA-U.Porto & FCUP), Gabriella Gilli (IA-U,Lisboa
PhD Topic (2019/139): Unveiling the composition of exoplanets atmospheres with CHEOPS and ESPRESSO
Although several thousands of exoplanets have already been detected (see exoplanet.eu), our understanding of their atmospheres is still very limited. In most of the cases, our knowledge of an exoplanet can be reduced to its mass and radius (see Demangeon+2018). The last years have, however, seen considerable developments in terms of instrumentation. New missions like the ESA-CHEOPS satellite (Fortier+2014), the ESA-ARIEL project (Tinetti+2016) and the high resolution spectrograph ESPRESSO@ESO-VLT (Pepe+2014) will shed new lights on exoplanets and their atmospheres.
CHEOPS, ARIEL and ESPRESSO will provide complementary information. On one side, CHEOPS will probe the atmosphere of “hot jupiters” providing broad spectral measurement of the light reflected by these planets. ARIEL will complement that with low resolution spectra in the infra-red. On the other side, ESPRESSO will provide high resolution observation of these planets and their host stars, from which transmission spectra and specific spectral signatures can be extracted.
For this PhD project, the laureate will be involved in CHEOPS, ARIEL and ESPRESSO science team activities. The first objective will be to focus on the interpretation of CHEOPS and ESPRESSO data. A second step will be to participate to the scientific definition of the ARIEL mission whose launch is planned for 2028. Using state-of-the art models, inspired from those used to simulate the atmosphere of Solar System planets, the laureate will infer several properties of the observed atmospheres: their reflective properties (albedo, presence/characteristics of clouds, e.g. Demory+2013, Martins+2018), their temperature, the molecules and atoms which compose them (e.g. Birkby+2017). Due to the unprecedented precision and flexibility offered by CHEOPS and ESPRESSO on one side and the importance of the ESA-ARIEL mission for the future of exoplanet sciences. The results from this thesis will constitute landmarks in the field of exoplanetary atmospheres and help to shape the future of the field.
The supervisors of this project, along with the team which will host the laureate, has a deep involvement and expertise in both CHEOPS, ARIEL and ESPRESSO. They will guarantee the laureate access to the data, to sophisticated 3D atmospheric models and involvement in the science team’s activities.
Start date: 2019/10/01
2017/B017 Fellow: Akinsanmi A. Babatunde (finished)
PhD Topic (2017/131): Looking for rings and tides in transiting planets
Recent years have seen a revolution in our knowledge of exoplanetary systems including many surprising discoveries. In contrast, several expected results have not yet been observed or confirmed. Among these is the existence of moons and rings, as well as of tidal deformations of the exoplanets that orbit very close to their parent star. This project aims at detecting these extreme systems taking advantage of the unprecedented precision of the ongoing and future transit missions K2, TESS, CHEOPS and Plato, as well as of new high-resolution spectrographs such as ESPRESSO.
Our team is now particularly involved in the CHEOPS (ESA) mission, to be launched in 2018. CHEOPS (CHarecterising ExOplanets Satellite) is a new ESA mission that will allow to observe key bright targets with extreme characteristics. The development of CHEOPS is also intimately related to our strong participation in the ESPRESSO (ESO) high-resolution spectrograph for the VLT telescopes.
ESPRESSO will allow deriving radial velocity measurements with an unprecedented precision, and hence it will permit to measure masses for the smallest known exoplanets. Together, CHEOPS and ESPRESSO will give us a unique opportunity to characterize the properties (mass, radius, composition, structure, shape) of exoplanets.
In particular, in this project we propose to upgrade a state of the art Bayesian transit and radial velocity fitting code to include rings, planetary occultations, Rossiter-McLaughlin effect, and tidal effects. Rings have never been detected around extra-solar planets, but their signature should be present in both the transit light and radial-velocity curves (through Rossiter-McLaughlin effect). The tidal star-planet interactions deform the planets, producing also significant deformation in the light curve (never detected, but expected for some short period planets). Hence, the code will allow searching for the signature of rings, planetary occultations, and tidal effects. All these effects have been predicted by theory but they were never observed: the new set of instruments will allow us to make a breakthrough in this domain.
Our team has privileged access to Cheops data hence the student will be able to access this unique dataset. Furthermore, the tools developed during this project we may also use for other datasets: NASA K2, TESS missions and in the future for ESA PLATO mission. The results of this project will increase the scientific exploitation of these state of the art missions and lead to a better understanding of planetary systems.
Start date: 2017/10/01
2017/B016 Fellow: Luís Filipe R. Pereira (ongoing)
PhD Topic (2017/126c): Detection and characterization of planets orbiting oscillating red-giant stars with NASA’s TESS mission
The Transiting Exoplanet Survey Satellite (TESS) is a NASA space mission, with launch scheduled for March 2018, that will perform an all-sky survey for planets transiting bright nearby stars. Furthermore, TESS’s excellent photometric precision, combined with its fine time sampling and long intervals of uninterrupted observations, will enable asteroseismology (i.e., the study of stars by the observation of their natural, resonant oscillations) of solar-type and red-giant stars. Asteroseismology is proving to be particularly significant for the study of red-giant stars while quickly maturing into a powerful tool whose impact is being felt more widely across different domains of astrophysics. A noticeable example is the synergy between asteroseismology and exoplanetary science. TESS hence offers the exciting prospect of conducting asteroseismology on a significant number of evolved exoplanet-host stars. The main goal of this project will be to use TESS photometry to systematically detect and characterize transiting planets orbiting oscillating red-giant stars. To that end, we propose an end-to-end PhD project that will provide the student with skills in transit photometry analysis, asteroseismic data analysis and stellar modeling, and radial-velocity/spectroscopic techniques. The implications of this project are far-reaching. The proposed systematic search for transiting planets orbiting oscillating red-giant stars is expected to provide new insights into some of the outstanding problems in exoplanetary science, namely, on the planet occurrence rate as a function of stellar mass/evolutionary state, on the correlation between stellar metallicity and planet occurrence around evolved stars and on the structural aspects of gas- giant planets.
Start date: 2017/10/01
2016/B015 Fellow: Ruben H. M. Gonçalves (finished)
PhD Topic (2016/122): Planetary atmospheres – From Solar System to Exoplanets: Atmospheric Characterization and Search for Chemical Desequilibrium Compounds
High-resolution visible and infrared (in the CO2 transparency windows) spectroscopic capabilities to the Solar System planets opens a new window by accessing atmospheric composition, mixing ratios and isotopic ratios, in particular, the measurement of the spectral lines’ Doppler shifts allows the retrieval of wind velocities and thus contribute to constrain planetary circulation dynamics.
Solar System observations and data reduction techniques, besides their own relevance research sake, serve as a stepping-stone for the study of extrasolar planets. In this project we propose to use them as a starting point for the development and test of atmospheric characterization tools. In a second phase the fine-tuned protocols will be adapted and applied to exoplanetary targets in order to constrain their atmospheric composition. The research will be focused in the presence of chemical disequilibrium compounds.
Starting date: 2016/10/01
2016/B014 Fellow: Saeed Hojjatpanah (finished)
PhD Topic (2016/123): The Awakening of the ESPRESSO Planet-hunter: Finding a Twin of Earth
In 2018 the most anticipated planet-hunter machine will go online. From Paranal Observatory, the ESPRESSO spectrograph will be able to record with unprecedented precision the radial velocity of nearby stars. Its declared goal is clear: to find an Earth-mass planet inside the habitable zone around a star similar to our very own. The Institute of Astrophysics and Space Sciences (IA) has been behind the development of ESPRESSO since its inception, participating in the design and construction, and maximizing the scientific output of the spectrograph. As we enter this very last stage of the project, we have to put together the information we gathered on which stars are we more likely to detect earth-like planets, and define the final ESPRESSO catalog. The student will make use of data from two recently awarded ESO proposal datasets, on HARPS and UVES spectrographs, to pave the way to ESPRESSO and assist on the very first observations of the instrument. This will be done, specifically by studying the stellar granulation and activity signatures of our own star, the Sun, and by using high-resolution spectra to investigate the key stellar characteristics of the main planet-host candidates.
Starting date: 2016/10/01