THESIS ANNOUNCEMENTS
PhD thesis
Professor: Dr. Rodolfo Angeloni
Co-supervisor: Dr. Claudia Paladini, VLTI Operations Staff Astronomer
European Southern Observatory
Thesis available
A Tale of Giants and How They Start Losing Mass
Abstract
Stars with low to intermediate initial mass (≲ 8 M⊙), including our Sun, undergo a short evolutionary phase, called the Asymptotic Giant Branch (AGB), towards the end of their lives and undergo several mass dredge-up events. Stars on the AGB usually have O-rich chemistry. However, after the third dredge-up, stars with initial masses between 1 and 4 M⊙ can reach a C/O ratio > 1, and their spectra are then dominated by C-bearing molecular and dust species.
The atmosphere of a star on the AGB can be as large as a few AU, and it is stripped away by a stellar wind on a typical time-scale of thousands of years. The material stripped away feeds the interstellar medium becoming a building block for the new generation of stars, planets, and eventually life. Therefore the mass-loss process is a key ingredient for our understanding of many fields of astrophysics, including stellar evolution and the chemical enrichment of the interstellar medium via stellar yields.
This project aims at tackling one of the key open questions in the field of evolved stars: what is driving the wind and what are the precursor of dust formation in Oxygen-rich atmospheres. The approach will be both theoretical and observational. State-of-the-art model predictions including dust formation will be calculated, and compared with observations from the high angular resolution interferometer VLTI. The angular resolution of the VLTI allows spatially resolving the atmospheric layers where dust is forming. A rich data set from the VLTI/MIDI Large Program is already available. The student is also expected to analyze a new data set from the second generation VLTI/MATISSE instrument which is currently being observed.
Co-supervisor: Dr. Claudia Paladini, VLTI Operations Staff Astronomer
European Southern Observatory
Thesis available
A Tale of Giants and How They Start Losing Mass
Abstract
Stars with low to intermediate initial mass (≲ 8 M⊙), including our Sun, undergo a short evolutionary phase, called the Asymptotic Giant Branch (AGB), towards the end of their lives and undergo several mass dredge-up events. Stars on the AGB usually have O-rich chemistry. However, after the third dredge-up, stars with initial masses between 1 and 4 M⊙ can reach a C/O ratio > 1, and their spectra are then dominated by C-bearing molecular and dust species.
The atmosphere of a star on the AGB can be as large as a few AU, and it is stripped away by a stellar wind on a typical time-scale of thousands of years. The material stripped away feeds the interstellar medium becoming a building block for the new generation of stars, planets, and eventually life. Therefore the mass-loss process is a key ingredient for our understanding of many fields of astrophysics, including stellar evolution and the chemical enrichment of the interstellar medium via stellar yields.
This project aims at tackling one of the key open questions in the field of evolved stars: what is driving the wind and what are the precursor of dust formation in Oxygen-rich atmospheres. The approach will be both theoretical and observational. State-of-the-art model predictions including dust formation will be calculated, and compared with observations from the high angular resolution interferometer VLTI. The angular resolution of the VLTI allows spatially resolving the atmospheric layers where dust is forming. A rich data set from the VLTI/MIDI Large Program is already available. The student is also expected to analyze a new data set from the second generation VLTI/MATISSE instrument which is currently being observed.
Professor: Dr. Rodolfo Angeloni
Student: Piera Soto
Characterizing the Symbiotic Population in the Magellanic Clouds
Abstract
Symbiotic stars are long-period interacting binaries composed of a hot compact star, a late-type giant star, and a tangled network of a gas and dust nebulae. They represent unique laboratories to study several poorly understood astrophysical phenomena and their reciprocal influence.
The consistency of the symbiotic population is matter of debate, mainly because of the striking difference between the number of observed vs predicted symbiotic stars. Nowadays in the Magellanic Clouds there are 22 confirmed and 36 candidates symbiotic stars. This project aims at characterizing the symbiotic population of the Magellanic Clouds through optical-NIR medium resolution spectroscopy.
Student: Piera Soto
Characterizing the Symbiotic Population in the Magellanic Clouds
Abstract
Symbiotic stars are long-period interacting binaries composed of a hot compact star, a late-type giant star, and a tangled network of a gas and dust nebulae. They represent unique laboratories to study several poorly understood astrophysical phenomena and their reciprocal influence.
The consistency of the symbiotic population is matter of debate, mainly because of the striking difference between the number of observed vs predicted symbiotic stars. Nowadays in the Magellanic Clouds there are 22 confirmed and 36 candidates symbiotic stars. This project aims at characterizing the symbiotic population of the Magellanic Clouds through optical-NIR medium resolution spectroscopy.
Professor: Dr. Rodolfo Angeloni
Co-supervisor: Dr. Francesco Di Mille, Technical Operation Manager
Las Campanas Observatory, Carnegie Institution of Washington
Student: Eunice Perez
Panchromatic Studies of Symbiotic Stars at all Time-Scales
Abstract
Symbiotic stars are wide interacting binaries composed of a hot compact star, an evolved giant star, and a tangled network of gas and dust nebulae. They represent unique laboratories for studying a variety of important astrophysical problems, and are among the most promising candidates as progenitors of SNIa.
This project aims at studying the complex photometric variability of a significant sample of galactic and extragalactic symbiotic stars, across several passbands and different temporal scales: from the shortest ones (~minutes) informing on the accretion processes occurring at the inner boundary of the accretion disk, up to the longest ones (years), result of the very large binary separation and consequent long orbital motion.
Through a unique combination of literature, archival and proprietary data, and by careful visual inspection and combined time series analysis techniques, the goal is 1) to investigate - for the first time in a systematic way - the nature of the cool component, by providing its first-order pulsational ephemerides; 2) to characterize the type of accretion process at work (e.g., Roche-Lobe overflow or wind-accretion) by looking for reflection effects and ellipsoidal modulation in the multicolor light curves; 3) to search for rapid photometric variability able to identify the presence of a magnetic white dwarf in the system; and, finally, 4) to link all this information with the physical parameters of the binary system as a whole.
Along this line, the student is also invited to contribute to RAMSES II, a Gemini Observatory Instrument Upgrade Project that has recently provided the astronomical community with the first photometric tool for hunting symbiotic stars in the local Universe.
Co-supervisor: Dr. Francesco Di Mille, Technical Operation Manager
Las Campanas Observatory, Carnegie Institution of Washington
Student: Eunice Perez
Panchromatic Studies of Symbiotic Stars at all Time-Scales
Abstract
Symbiotic stars are wide interacting binaries composed of a hot compact star, an evolved giant star, and a tangled network of gas and dust nebulae. They represent unique laboratories for studying a variety of important astrophysical problems, and are among the most promising candidates as progenitors of SNIa.
This project aims at studying the complex photometric variability of a significant sample of galactic and extragalactic symbiotic stars, across several passbands and different temporal scales: from the shortest ones (~minutes) informing on the accretion processes occurring at the inner boundary of the accretion disk, up to the longest ones (years), result of the very large binary separation and consequent long orbital motion.
Through a unique combination of literature, archival and proprietary data, and by careful visual inspection and combined time series analysis techniques, the goal is 1) to investigate - for the first time in a systematic way - the nature of the cool component, by providing its first-order pulsational ephemerides; 2) to characterize the type of accretion process at work (e.g., Roche-Lobe overflow or wind-accretion) by looking for reflection effects and ellipsoidal modulation in the multicolor light curves; 3) to search for rapid photometric variability able to identify the presence of a magnetic white dwarf in the system; and, finally, 4) to link all this information with the physical parameters of the binary system as a whole.
Along this line, the student is also invited to contribute to RAMSES II, a Gemini Observatory Instrument Upgrade Project that has recently provided the astronomical community with the first photometric tool for hunting symbiotic stars in the local Universe.
Master Thesis
(en español)
Estudiante: Juan Pablo Uchima
Caracterizando los Cielos de la Región Estrella
Análisis cuantitativa del brillo superficial y extinction atmosférica desde sitios seleccionados de interés astronómico, naturalístico, y turístico
Resumen
El presente proyecto de tesis de magister mira a establecer el primer mapa cuantitativo de brillo superficial y extinción atmosférica desde sitios de interés astronómico, naturalístico y turístico ubicados en la Región de Coquimbo, Chile. A través de un monitoreo continuado a lo largo de (mínimo) dos años, nos proponemos de medir valores y variaciones temporales (periódicas y no) de la calidad del cielo nocturno, con el fin de caracterizar la natural extinción atmosférica y la creciente degradación debida a la contaminación lumínica, por así contribuir a preservar el cielo nocturno para que nuestras generaciones futuras puedan seguir disfrutando de este invaluable patrimonio cultural. El proyecto es fruto de la colaboración entre la Universidad de La Serena (ULS), el Observatorio de Las Campanas (LCO), y la Oficina de Protección de la Calidad del Cielo del Norte de Chile (OPCC).