Found 55 talks archived in Planetary systems
Planetary systems have been found systematically orbiting main sequence stars and red giants. But the detection of planets per se during the white dwarf phase has been more elusive with only 3 systems. We have, however, ample indirect evidence of the existence of planetary debris around these systems in the form of material acreted onto the white dwarf, disks and even planetesimals. In this talk, I will review how we can put the pieces together: how we can reconcile what we see in white dwarfs with what we can infer regarding the evolution of planetary systems from the main sequence phase.
En los ultimos años hemos visto el desarrollo de instrumentación para la búsqueda de exoplanetas por el método de la Velocidad Radial.
La tendencia es que cada generación de espectrógrafos ultra-estables sea un orden de magnitud mejor que la anterior. Pero ¿qué tienen en común estos intrumentos?, ¿Qué los distingue del resto?
El IAC participa en instrumentos de tres generacines: HARPS3, ESPRESSO y HIRES; en esta charla, aprovechando la experiencia adquirida, se hablará de las estrategias que han permitido a estos instrumentos tener alta resolución, alta estabilidad y alta repetibilidad.
Stellar magnetic activity generates astrophysical noise on the collected data in the quest for what might be called Earth 2.0. This noise poses obstacles and difficulties in the detection and accurately determining small-sized exoplanets properties. Characterising the relation between stellar photometric variability and radial velocity jitter can help us to define optimal observational strategies, and also to better model and mitigate the activity noise. Moreover, stellar activity will remain as one of the biggest challenges in detecting and assessing the exoplanetary atmosphere’s signal, even in the era of upcoming missions. I will present the current view of the intricate relationship between exoplanets and activity, discuss some of the latest developments, and show some of our first results.
Atmospheric compositions can provide powerful diagnostics of formation and migration histories of planetary systems. In this talk, I will present the results of our latest survey of atmospheric compositions focused on atmospheric abundances of H2O, Na, and K. We employ a sample of 19 exoplanets spanning from cool mini-Neptunes to hot Jupiters, with equilibrium temperatures between ~300 and 2700 K. We employ the latest transmission spectra, new H2 broadened opacities of Na and K, and homogeneous Bayesian retrievals. We confirm detections of H2O in 14 planets and detections of Na and K in 6 planets each. Among our sample, we find a mass-metallicity trend of increasing H2O abundances with decreasing mass, spanning generally substellar values for gas giants and stellar/superstellar for Neptunes and mini-Neptunes. However, the overall trend in H2O abundances, is significantly lower than the mass-metallicity relation for carbon in the solar system giant planets and similar predictions for exoplanets. On the other hand, the Na and K abundances for the gas giants are stellar or superstellar, consistent with each other, and generally consistent with the solar system metallicity trend. The H2O abundances in hot gas giants are likely due to low oxygen abundances relative to other elements rather than low overall metallicities, and provide new constraints on their formation mechanisms. Our results show that the differing trends in the abundances of species argue against the use of chemical equilibrium models with metallicity as one free parameter in atmospheric retrievals, as different elements can be differently enhanced.
Zoom link: https://rediris.zoom.us/j/92734027825
Planetary transits have proven to be one of the most efficient means of finding planets outside the Solar system, counting over 2500 exoplanet discoveries. These transiting planets are paramount for the study of exoplanet atmospheres as the stellar light is filtered through the planetary atmosphere during transit and planetary absorption signatures become imprinted on the stellar spectrum. Observations of hot-Jupiter transmission spectra have become increasingly numerous and reliable throughout recent years, allowing detailed constrains on the planet's physical and chemical atmospheric properties, interactions between planet and host star, and planet formation history. While early work relied largely on space-based facilities, ground-based techniques have seen major advances recently and have become instrumental in performing an extensive and comparative study of exoplanet atmospheres. I will review the current state of knowledge, summarize recent results and discuss future prospects of exoplanet characterization, with a focus on the potential of ground-based facilities. In particular, I will present recent and new results by our team on the transmission spectra of hot Jupiters.
With more than 3000 detected exoplanets it is now clear that planet formation is a natural outcome of stellar
formation. However, the mechanisms by which planets do form remain uncertain. The most promising way to understand
this process is to study protoplanetary disks that show signposts of planet formation: the so-called transitional
disks. In this talk I will first introduce the observational techniques and instruments that are revolutionizing this field
I will finish presenting ALMA and SPHERE/VLT observations of transitional disks around low-mass stars
that, according to our current understanding, show evidences of planet-disk interactions.
While there may be some possibilities of detecting biological signatures (“biomarkers”) outside the Solar System from the ground, most authorities
believe that major installations in space are required to do so.
In this talk we present the background, a brief summary of possible biomarkers, of possible targets and of the ways and means to observe them.
In my presentation I will give a short introduction to the science of extrasolar planets, in particular the technique of transit, eclipse and phasecurve spectro-photometry. I will describe my various projects in this emerging field using state of the art spectroscopic and photometric instruments on the largest ground based telescopes, the 'flying telescope' SOFIA (Stratospheric Observatory for Infrared Astronomy) and the Kepler and Hubble space telescopes.
Time is one of the least explored dimensions of exoplanet research; most
stars targeted by large surveys are middle-aged by necessity or statistics.
Yet the first few hundred million years of a planetary system are probably
the most formative and include accretion, migration, and escape of atmospheres.
While the Kepler prime field included a small number of young stars by chance, the
K2 mission is deliberately selecting some target stars by age, and previews the
potential of TESS and PLATO. The Zodical Exoplanets in Time (ZEIT) project studies
K2 systems in stellar clusters of established ages. Transiting planets as small as
Earth-size have been detected in the Upper Scorpius, Pleiades, Hyades, and Praesepe
clusters. Mysterious aperiodic signals related to circumstellar disks were found in
Upper Scorpius, these may be related to planet formation. We are also investigating
planets around evolved stars and report a Jupiter-mass planet inflated by irradiation
from its host star. Gaia distances, proper motions, and spectra can identify large numbers
of young stars for observation by the TESS and PLATO missions, enabling robust comparisons
across a range of ages to understand evolutionary trends, and select propitious targets for
follow-up by ELTs and space observatories such as JWST.
As of today, we know now more than 3000 planets orbiting other stars. The detection of planets through radial velocity gathers special attention in the world of exoplanet characterization, as this technique will probably allow us to detect and characterize the first Earth-mass planet inside the habitable zone of a neighbouring star. In this talk I will discuss the ongoing efforts for developing state-of-the art spectrographs that permit the detection of an Earth twin, and discuss one of the most formidable obstacles to the detection of planetary signals: stellar activity. While for several years planetary surveys simply avoided active stars, today we know that the presence of extrasolar planets around a star might suppress stellar activity as we measure it, or even boost it. I will present the current view of the intricate relationship between exoplanets and activity, and discuss some of the latest works on the topic.
- IAU G5 -- The GALAH survey: science goals and highlights to dateSarah MartellTuesday January 25, 2022 - 10:30 GMT (Online)
- Dynamos, the drivers of solar and stellar activityProf. Axel BrandenburgThursday January 27, 2022 - 10:30 GMT (Online)