terça-feira 28 de novembro
SALÓN AZUL
09:00 - 09:50
Plenary Review Talk
Invited Speaker:
Laurence Sabin
- Instituto de Astronomía (Ensenada), UNAM
(México)
[cv]
Laurence Sabin
Instituto de Astronomía (Ensenada), UNAM
Curriculum Vitae:
La Dra Sabin completó su doctorado en la Universidad de Manchester (Jodrell Bank Center for Astrophysics, UK) y llevó a cabo una parte de esos estudios en el Instituto de Astrofísica de Canarias (Tenerife). Su especialización se centra en el análisis de estrellas evolucionadas de masa intermedia (como nebulosas planetarias, estrellas simbióticas, novas …) y a veces de masa alta (e.g. remanentes de supernova) tanto para su detección y caracterización usando grandes catastros de cielo, como para el estudio de los campos magnéticos asociados a dichos objetos. La Dra. Sabin es miembro del Instituto de Astronomía de la UNAM en Ensenada, donde desempeña su labor como investigadora. También es parte de varios grupos de investigación a nivel nacional (Grupo de Estudio de Estrellas evolucionadas del IA-Ensenada, Grupo Nacional de Polarización en Astronomía), así como de grupos internacionales (Consorcio EGAPS, Consorcio SAINT-EX y Grupo de investigación de nebulosas alrededor de estrellas evolucionadas).
Chair: Julio Carballo-Bello
#024 |
From Post-AGBs to White Dwarfs: Exploring the Fascinating Evolution of Intermediate Mass Stars
Laurence Sabin
1
1 - Instituto de Astronomia, UNAM (Mexico).
Resumo:
I will present the latest studies on the evolution of intermediate mass stars, specifically from the post-AGBs to white dwarf phase, all of which are shedding new light on these fascinating astronomical objects. It is known that intermediate mass stars undergo complex physical (and chemical) processes as they evolve from post-AGBs to white dwarfs, with significant changes in their physical properties occurring during different stages of their evolution. I will present different combinations of observational data and theoretical models used to investigate the various phenomena that occur during this evolution, such as mass loss and the formation of planetary nebulae. These studies are essential for advancing our understanding of the life cycle of stars and their contribution to the chemical enrichment of the universe. The findings from these studies may also have significant implications for our understanding of the formation and evolution of planetary systems around other stars. Overall, these latest studies provide valuable insights into the complex and intriguing processes that occur during the evolution of intermediate mass stars.
09:50 - 10:20
Plenary Target Talk
Invited Speaker:
Bruno Dias
- Instituto de Astrofísica, Universidad Andrés Bello
(Chile)
[cv]
Bruno Dias
Instituto de Astrofísica, Universidad Andrés Bello
Curriculum Vitae:
Bruno Dias is a professor at the Institute of Astrophysics, Universidad Andrés Bello (UNAB), Chile, with 46+ refereed publications (2010-2023). Bruno got a PhD from Universidade de São Paulo, Brazil in 2014, including an ESO studentship, which gave him two prizes for best thesis at the same university. He worked as a postdoctoral researcher at Durham University, UK and Universidad Andrés Bello, Chile, besides being awarded an ESO fellowship. He has been an independent researcher of the Instituto de Alta Investigación, Universidad de Tarapacá, Chile. His main research line is on stellar populations of the Milky Way and Local Group galaxies, in particular studying their star clusters. Bruno is the PI of the VISCACHA survey that is the project with more accumulated nights at SOAR telescope, using adaptive optics to obtain deep and spatially resolved photometry of star clusters in the Magellanic Clouds, and spectroscopic follow-up with GMOS/Gemini. The big goal of VISCACHA is to trace the past chemo-dynamical history of the Magellanic Clouds using their star cluster population as well as to analyse the internal structure, kinematics and stellar populations within individual clusters. Among his main personal objectives, Bruno wishes to produce high-level science with Latin America astronomers, which is evident with the VISCACHA team of about 40 members in Brazil, Chile, Argentina, México, and 12 VISCACHA or VISCACHA-related refereed papers since 2019 and growing, as well as active research grants in Chile, Brazil, and fund raising for scientific meetings. Bruno also created the ESO Python Boot Camp and gave the first steps to move ESO Paranal systems to Python. Bruno co-created, directed and taught in the Diplomado en Astronomía General at UNAB, the only in Chile. Bruno is also a member of the VVVX, SDSS-V, SPLUS survey teams, and MOSAIC/ELT science team. Last but not least, he is the current president of Chilean Astronomical Society (2023-2024) and president of the IAU-NCA in Chile, working to develop Astronomy in Chile, which hosts more than 50% of the global collecting area from ground-based telescopes.
Chair: Julio Carballo-Bello
#108 |
The VISCACHA survey: The Magellanic Clouds and their star clusters
Bruno Dias
1
1 - Instituto de Astrofísica, Universidad Andrés Bello, Chile.
Resumo:
The Large and Small Magellanic Clouds (LMC and SMC) are the two most massive satellite galaxies surrounding the Milky Way. They are likely in their first infall to our Galaxy and have just passed pericentre. Their orbit has been dragging a 200 degrees-long gas trailing stream and also a leading gas structure. The LMC-SMC pair has been interacting to each other with multiple encounters throughout their lives, which heavily impacted their structure, triggered star formation and boosted star cluster dissolution. The chemical evolution of these two galaxies is much less efficient than expected, and they are different in various regions of the SMC for example. Understanding this complex history requires a lot of precise chemical and kinematic information as a function of time and space combined to sophisticated chemo-dynamical models. The star clusters are excellent fossils because we can measure their 3D position, 3D velocities, age, metallicity, internal structure, and they trace the different regions of the LMC and SMC, as well as covering a large age range. In this talk, I will briefly review the topic, present the VISCACHA survey that I lead involving astronomers from a handful of Latin America countries producing high-level science with star clusters in this context and a dozen papers so far.
10:20 - 11:00
COFFEE BREAK
11:00 - 12:30
F: Planetary Systems & Astrobiology
Exoplanetary atmospheres and composition
Chair: Carolina Agurto
#492 |
Simulation of potentially habitable environments on the surface of exoplanets
Paola Cunha
1
;
Luan Ghezzi
1
;
Douglas Galante
2
;
Evandro Silva
2
;
Fabio Rodrigues
2
;
Ana Carolina Carvalho
2
;
Junia Schultz
3
;
Alexandre Rosado
3
;
Amanda Bendia
2
1 - Valongo Observatory.
2 - University of Sao Paulo.
3 - King Abdullah University of Science and Technology.
Resumo:
M-dwarfs comprise 75\% of the stars in the Milky Way and also host a large fraction of the potentially habitable exoplanets. However, the high levels of stellar activity are a challenge in a biological conext. They exhibit frequent and intense flares, exposing their planets to high levels of ultraviolet (UV) radiation. This radiation is crucial for biological systems, but excessive exposure can cause damage to important cell structures. Thus, the aim of this work is to investigate whether life could withstand the environmental conditions of planets orbiting M-dwarfs. For our analysis, we choose, Proxima Centauri b, an exoplanet discovered in 2016 and recently confirmed. It has 1.17 times the mass of Earth and is located in the habitable zone of the system, which is a favorable characteristic for life as we know it. To obtain the results, we performed irradiation experiments with the yeast Rhodotorula collected in Diamantina, MG. The first experiment was performed with a tubular lamp that covers only the UVC region. The second experiment was conducted with a continuous spectrum lamp that covers the entire UV range. The last experiment was carried out in the Space and Planetary Simulation Chamber (AstroCam) to simulate hypothetical conditions on the surface of Proxima b. We simulated atmospheres of 100\% CO$_2$ and primitive Earth (80\% CO$_2$ and 20\% N$_2$), with a pressure of 1000 mbar, and the continuous spectrum lamp coupled to AstroCam. The results showed that irradiations using the continuous spectrum lamp are more lethal than the tubular lamp. Additionally, we observed that cells resisted to a dose of 60000 J/m$^2$ for the UVC lamp. Assuming an average flux value for the flares on Proxima b (7 W/m$^2$), this dose would be reached in about 2.38 hours. Our results provide important data to guide studies searching for biosignatures on exoplanets.
#140 |
Physical Properties and Chemistry of Dust Clouds in Extrasolar Atmospheres
Genaro Suárez
1
;
Johanna Vos
2
;
Stanimir Metchev
3
;
Jacqueline Faherty
1
;
Kelle Cruz
4
1 - American Museum of Natural History.
2 - Dublin Institute for Advanced Studies.
3 - The University of Western Ontario.
4 - Hunter College.
Resumo:
Clouds influence most aspects of extrasolar atmospheres and, therefore, shape their emergent spectra. Studying these clouds is essential to learn about the thermal structure, composition, detectability, and habitability of planetary atmospheres. In anticipation of JWST observations of cloudy exoplanet atmospheres, we analyze all Spitzer mid-infrared spectra of ultracool dwarfs and find the following results, which constitute a paper series: 1) silicate clouds are near ubiquitous in (L-type) extrasolar atmospheres, 2) these clouds form, then thicken, and sediment in the 2000-1300 K effective temperature range, 3) young atmospheres are cloudier due to a slower settling of dust clouds, 4) variable objects are more likely to have higher dust cloud opacity, and 5) equatorial latitudes are cloudier compared to the poles. These results significantly grow our knowledge of the formation, composition, and evolution of dust clouds in extrasolar atmospheres and partially explain the spectral diversity observed in directly-imaged exoplanets and brown dwarfs by invoking their viewing geometry. Our ongoing JWST higher resolution and SNR observations of extrasolar atmospheres will further inform about the physical properties and chemistry of dust clouds.
#168 |
The Composition of Beta Pic Molecular Cloud as traced by HD 181327 and the Formation of Beta Pic b
Henrique Reggiani
1
;
Jhon Galarza
2
;
David K. Sing
3
;
Kevin C. Schlaufman
3
;
Brian F. Healy
4
;
Andrew McWilliam
2
;
Joshua D. Lothringer
5
1 - NOIRLAB.
2 - The Carnegie Observatories.
3 - William H. Miller III Department of Physics and Astronomy, Johns Hopkins University.
4 - School of Physics and Astronomy, University of Minnesota.
5 - Department of Physics, Utah Valley University,.
Resumo:
Protoplanetary disk and giant planet formation models have been interpreted to suggest that a giant planet's atmospheric abundances can be used to infer its formation location in its parent protoplanetary disk. It has been reported that the hot Jupiter $\beta$ Pictoris $b$ has subsolar carbon and oxygen abundances ratios. Assuming solar carbon and oxygen abundances for its host star $\beta$ Pictoris, $\beta$ Pictoris $b$'s atmospheric carbon and oxygen abundances possibly indicate that it slowly formed via core-acretion somewhere between the disk's H$_{2}$O and CO$_{2}$ ice lines. However, due to $\beta$ Pic's photospheric parameters, it is notoriously difficult to directly infer carbon and oxygen abundances from $\beta$ Pictoris. We characterize star HD 181327, part of $\beta$ Pictoris's moving group, and argue that its stellar abundances are the best way to infer the elemental composition of the protoplanetary disk from which $\beta$ Pictoris $b$ was formed. We also perform our own retrieval of $\beta$ Pic $b$. Our inferred C/O abundances for HD 181327 and $\beta$ Pic $b$ corroborates the scenario outlined by previous studies, showing $\beta$ Pic $b$ formed via core-accretion beyond the water ice line. We reinforce that giant planet atmospheric abundance ratios can only be meaningfully interpreted relative to the possibly non-solar mean compositions of their parent protoplanetary disks.
#217 |
A modern view of giant planet interiors
Yamila Miguel
1
1 - Leiden Observatory / SRON.
Resumo:
We are at a unique time to study giant exoplanets. With more than 5000 exoplanets found and facilities like JWST that provide unprecedented data on their atmospheres, we moved from an era of discovery to an era of exoplanet characterisation. On the other hand, extremely accurate measurements by Juno and Cassini missions, make this an exceptional time to combine the detailed information on the solar system's giant planets and the large amount of data from exoplanets to get a better understanding of planetary physics and a better comprehension on planet formation and evolution.
Because the giant planets in our solar system are and will remain to be the touchstone to understanding the detailed processes that happen in these worlds, in this talk I will present my recent study on the amount and distribution of heavy elements in Jupiter’s interior and I will also discuss the implication of this study on giant exoplanets, presenting some unpublished work towards a better characterisation of giant exoplanet interiors using JWST data.
#456 |
Effects of Pressure Dependency in Exoplanetary Atmospheric Retrieval
Aline Novais
1
1 - Observatório do Valongo, Universidade Federal do Rio de Janeiro.
Resumo:
Although the analysis of exoplanet atmospheres has become one of the most pertinent topics within planetary sciences, characterising these objects directly from their spectra is still a challenge. To interpret the observed spectrum of an exo-atmosphere, one can apply a technique known as atmospheric retrieval, i.e. fitting a model to this data in order to infer the properties of the atmosphere, such as temperature, chemical composition, and presence of clouds. This work considers a retrieval framework which includes H2O as the main molecular opacity source, and optional opacity features such as additional molecules (e.g. CH4, CO2, CO), collision-induced absorption (CIA), Rayleigh scattering, and clouds. Furthermore, our retrieval code accounts for a non-isobaric transit chord, setting atmospheric opacity sources to a full pressure dependency. We perform non-isobaric retrievals in 38 Hubble Space Telescope Wide Field Camera 3 (WFC3) near-infrared transmission spectra to establish how the variation of pressure affects the estimation of atmospheric parameters. Our results show that, for WFC3 wavelength range and resolution, mainly H2O-only cloud-free and constant/grey cloud atmospheres are retrieved. We compare our findings with previous analyses in the literature, concluding that Rayleigh scattering is negligible in most of our retrievals, except in the ones where shorter-wavelength WFC3 data is available. On the other hand, CIA is strongly dependent on pressure, therefore helping set the H2O abundance, which is unclear in the former isobaric studies. Additionally, we acknowledge the degeneracy between molecular abundances and the reference parameter (i.e. where the atmosphere is optically thick), as pointed out by previous studies, may be broken for cloud-free fits, but is still indirectly present in cloudy results. Finally, we suggest new approaches that could help identify additional atmospheric features imprinted in the spectra, considering data in complementary wavelengths, as well as retrieval analyses using higher-quality James Webb Space Telescope spectra.
#173 |
A comprehensive homogeneous investigation of orbital ephemeris and transmission spectrum of WASP-19 b.
Anitha Raj Rajkumar
1
;
Jeremy Tregloan-Reed
1
1 - Universidad de Atacama.
Resumo:
Exoplanets with ultra-short periods (P < 1 day) might experience orbital decay due to the tidal dissipation effect with the host star. My current work allows verification of the orbital ephemeris of the WASP-19b with the availability of long-term high-precision photometric and spectroscopic data including 20 unpublished transits from the Danish telescope. This place limits on the modified tidal quality factor Q’*.
The same data allows for a detailed study of the atmospheric properties of WASP-19b, via transmission photometry and spectroscopy. WASP-19A is an active host star with its surface littered with starspots, which if not correctly modeled, systematics are introduced into the transit timing measurements and transit depth, which latter affects the exoplanetary transmission spectrum. Additionally the signal from stellar inhomogeneities can outweigh the signal from planetary spectral characteristics (Rackham, B., V., et al. 2022, arXiv, 220109905, submitted to RAS Techniques and Instruments as invited review.). Therefore, to perform a full and complete orbital ephemeris study of WASP-19b requires the modeling of detected starspots. Incidentally, failing to model both occulted and unocculted starspots can skew measurements in the planetary radius affecting the broadband transmission spectrum. Using the transit-starspot model, PRISM we perform the most complete, detailed, homogeneous analysis of all available data to estimate Q’* and study the atmospheric properties of WASP-19b with the help of ground- and space-based archival data.
12:30 - 14:30
LUNCH
14:30 - 15:20
Plenary Review Talk
Invited Speaker:
Rodrigo Díaz
- Universidad de San Martín
(Argentina)
[cv]
Rodrigo Díaz
Universidad de San Martín
Curriculum Vitae:
Rodrigo Díaz es investigador en el Instituto de Ciencias Físicas, de doble dependencia UNSAM / CONICET. Es especialista en el análisis de datos astronómicos para la detección y caracterización de exoplanetas. Además, es profesor en la Universidad Nacional de San Martín, donde se desempeña como director de la Lic. en Ciencia de Datos.
Chair: Daniela Lazzaro
#606 |
Extrasolar planet discovery and characterisation in the era of James Webb and the data revolution
Rodrigo Díaz
1
1 - Instituto de Ciencias Físicas (ICIFI; CONICET) / Univ. de San Martín.
Resumo:
In the pursuit of unraveling the mysteries of our universe, the discovery and characterisation of extrasolar planets have been among the most captivating endeavours in modern astronomy. The processes of exoplanet formation and evolution have come into focus thanks to nearly 30 years of observational and theoretical efforts.
Amid this backdrop of discovery and exploration, the James Webb Space Telescope (JWST), with its spectroscopic and imaging instruments working across the infrared spectrum with unrivalled capabilities, is already providing an unprecedented window into the atmospheres of exoplanets, allowing us to probe their physical and chemical properties. This in turn sheds light on many aspects of the formation and evolution of planets.
At the same time, the data revolution is changing radically the way research is done in diverse fields of the physical sciences from particle physics to molecular dynamics to cosmology. The realm of exoplanetary science is no exception. Advancements in data science and machine learning are becoming indispensable tools to fully exploit the available data sets and to prepare for future instruments.
Indeed, exoplanetary science resides at the intersection of two waves of transformation, where the dynamic interplay between cutting-edge observational technology and data-driven analytical tools promise to usher a new era of discoveries and revelations.
In this talk, I present and overview of the latest advances in the field, with particular emphasis in the areas where the combination of data-driven techniques and new instrumentation has the potential to drastically advance the field. I also present part of the work conducted at the University of San Martín, where an interdisciplinary team of physicists, astronomers and computer scientists is harnessing the power of big data and innovative analytical techniques to extract valuable insights from an ever-expanding dataset.
15:20 - 15:50
Plenary Target Talk
Invited Speaker:
María Paula Ronco
- Instituto de Astrofísica de La Plata
(Argentina)
[cv]
María Paula Ronco
Instituto de Astrofísica de La Plata
Curriculum Vitae:
María Paula Ronco es doctora en Astronomía egresada de la Universidad Nacional de La Plata, Argentina. Fue investigadora postdoctoral NPF y FONDECYT en el Instituto de Astrofísica de la Pontificia Universidad Católica en Chile y actualmente es Investigadora Asistente de Conicet en el Instituto de Astrofísica de La Plata y docente en la UNLP. Es integrante del Grupo de Astrofísica Planetaria e Investigadora adjunta del Núcleo Milenio de Formación Planetaria en Chile. Se especializa en el estudio teórico de la evolución de discos protoplanetarios y en la formación y evolución de sistemas planetarios mediante simulaciones numéricas.
Chair: Daniela Lazzaro
#264 |
Disk evolution and planet formation around intermediate mass stars: The first step towards understanding white dwarf pollution
María Paula Ronco
1
;
Matthias R. Schreiber
2
;
Eva Villaver
3
;
Octavio Miguel Guilera
1
;
Marcelo Miguel Miller Bertolami
1
1 - Instituto de Astrofísica de La Plata.
2 - Departamento de Física, Universidad Técnica Federico Santa María.
3 - Centro de Astrobiología (CAB), CSIC-INTA,.
Resumo:
The study of protoplanetary disk evolution and theories of planet formation has predominantly concentrated on solar (and low) mass stars since they host the majority of the confirmed exoplanets. Nevertheless, the confirmation of numerous planets orbiting stars more massive than the Sun (up to 3Msun) has sparked considerable interest in understanding the mechanisms involved in the formation of exoplanets around such stellar objects. As intermediate mass stars are the progenitors of the currently observed white dwarf population, understanding planet formation around these stars is most likely related to the fact that 30 - 50 per cent of the known white dwarf population show signs of atmospheric pollution by planetary debris.
In this talk I will describe our latest results on protoplanetary disk evolution simulations which we developed as a first step towards a better understanding of planet formation around 1-3Msun stars. We investigated how the gas component of protoplanetary disks evolves considering different disk initial conditions such as different viscosities and initial masses of the disk, and by taking into account the effects of stellar evolution which become relevant as the mass of the central star increases. Our findings confirm that in general disks around more massive stars evolve faster than those around low-mass stars, except if low viscosities are considered. Our simulations also reveal four distinct evolutionary pathways for the gas component not reported before, which likely have a substancial impact on the dust evolution and thus on planet formation. I will also discuss these implications and present preliminar results of planet formation simulations around 1-3Msun stars.
15:50 - 16:20
Plenary Target Talk
Invited Speaker:
Tabaré Gallardo
- Universidad de la República
(Uruguay)
[cv]
Tabaré Gallardo
Universidad de la República
Curriculum Vitae:
Profesor Titular del Departamento de Astronomia del Instituto de Fisica de la Facultad de Ciencias (Udelar, Uruguay) dedicado a la dinamica de sistemas planetarios y de cuerpos menores, con enfasis en resonancias orbitales.
Chair: Daniela Lazzaro
#303 |
Orbital resonances in planetary systems
Tabare Gallardo
1
1 - Facultad de Ciencias, Udelar.
Resumo:
Orbital resonances are dynamic mechanisms characterized by some strength capable of overcoming other perturbations, managing to keep the planetary systems captured in the resonance.
There are two types of orbital resonances: mean motion resonances and secular resonances.
We will discuss here the mean motion resonances. They are located at some specific values of the semimajor axes but they occupy a non-negligible region of the semimajor axis space, which crucially depends on the orbital eccentricities as can be seen in the structures shown in the figure corresponding to the mutual resonances in the HD74156 system. The existence of a certain resonant width added to the fact that there are mechanisms that lead to resonances (through orbital migration for example) makes resonant systems frequent.
Several analytical models that have been proposed describe very well the resonant dynamics for low eccentricities and coplanar orbits, but when we go to inclined and eccentric orbits, the models become very complex, since they depend on long series expansions specific to each resonance, or they cannot be applied at all. The GBG21 semianalytical model (Gallardo, Beauge, Giuppone, 2021, A\\&A, 646, A148) is applicable in principle to all resonances without restrictions, it is especially good for eccentric and inclined systems and provides us with all the information that characterizes a resonance: location and width in semimajor axis, equilibrium points, libration periods, strengths and moreover, it describes very well the dynamical evolution in the vicinity of a resonance. This model also has the advantage of being implemented through a code that can be used without having to be a specialist in the subject. In this work we show how to apply the model to some planetary systems and how to interpret the results.
We will also briefly discuss the more complex problems of three-body resonances and resonant chains.
16:20 - 17:00
COFFEE BREAK
17:00 - 18:30
F: Planetary Systems & Astrobiology
Planetary Formation and Dynamics
Chair: Adrian Rodríguez
#349 |
Stellar Activity or a Planet?
Revisiting dubious planetary signals in M-dwarf systems
Daniela González
1
;
Nicola Astudillo-Defru
2
;
Ronald Mennickent
1
1 - Universidad de Concepción.
2 - Universidad Católica de la Santísima Concepción.
Resumo:
M dwarfs often exhibit magnetic activity that can affect radial velocity (RV) measurements inducing periodic signals that can be misinterpreted as planetary signals. GJ581, an M dwarf hosting a multiplanetary system, shows a reported stellar rotation period of 132 $\pm$ 6.3 days that closely matches the twice and four times the orbital periods of the d (66.6 days) and g (36.6 days) planets, respectively. This similarity raises questions about whether these signals are planets or artifacts of stellar rotation.
In this study, we reanalyze the RV time series of GJ581 using publicly available data from HARPS, HIRES and CARMENES, as well as stellar activity indicators. Our aim is to confirm or dismiss the existence of these dubious planetary signatures in the GJ581 system. We computed a Generalized Lomb-Scargle periodogram analysis on the RVs to identify periodic signals. Moreover, we used a Keplerian fit to model the RV time series and Gaussian Process (GP) regression to model the stellar activity indicators. Our analysis shows a stellar rotation period of 132.24 $^{+1.82}_{-1.71}$ days, which aligns with previous studies. However, the RVs temporal stability analysis suggest that the signal d may not be attributed to a planet. Further statistical analysis, such as a simultaneous fit of the RVs with a Keplerian model and the activity indices with a GP, is required to determine the more favorable model for the data. Once our analysis is consistent with previous work, it will be applied to other M dwarfs.
#566 |
Exploring protoplanetary disk evolution via magnetically driven winds
Elisa Castro Martínez
1
;
Octavio Miguel Guilera
2
;
Jose Luis Gomez
2
;
Sebastián Bruzzone
1
;
Julia Venturini
3
1 - Facultad de Ciencias, Universidad de la República, Montevideo.
2 - Instituto de Astrofísica de La Plata, Argentina.
3 - Department of Astronomy, University of Geneva, Switzerland.
Resumo:
Magnetically driven disk winds (MHD winds) are thought to be one of the main processes involved in the evolution and dispersal of protoplanetary disks, not only affecting the net accretion rate and gas mass loss but also introducing qualitative differences in the disk evolution in contrast with the classic alpha disk model, potentially impacting the formation and architecture of debris disks and planetary systems. We performed numerical simulations for the evolution of gas and dust protoplanetary disks, including viscous dissipation, X-ray photoevaporation and MHD winds, for different stellar masses and initial conditions of the disks. We studied the qualitative features observed in different disks and performed population synthesis in order to constrain the parameters that better reproduce the observables. Different disk wind regimes and viscous alpha parameters were implemented. Our presentation will focus on the obtained results and their correlation with key observables, such as gas accretion rates and lifetimes. The possible implications of these findings for planet and debris disk formation will also be discussed.
#122 |
Feedback-limited accretion: variable luminosity from growing planets
Matías Gárate
1
;
Jorge Cuadra
2
;
Matías Montesinos
3
;
Patricia Arévalo
4
1 - Max-Planck-Institut für Astronomie.
2 - Universidad Adolfo Ibáñez.
3 - Universidad de Viña del Mar.
4 - Universidad de Valparaíso.
Resumo:
Planets form in discs of gas and dust around stars, and continue to grow by accretion of disc material while available. Massive planets clear a gap in their protoplanetary disc, but can still accrete gas through a circumplanetary disc. For high enough accretion rates, the planet should be detectable at infrared wavelengths. As the energy of the gas accreted on to the planet is released, the planet surroundings heat up in a feedback process. We aim to test how this planet feedback affects the gas in the coorbital region and the accretion rate itself. We modified the 2D code FARGO-AD to include a prescription for the accretion and feedback luminosity of the planet and use it to model giant planets on 10 au circular and eccentric orbits around a solar mass star. We find that this feedback reduces but does not halt the accretion on to the planet, although this result might depend on the near-coincident radial ranges where both recipes are implemented. Our simulations also show that the planet heating gives the accretion rate a stochastic variability with an amplitude $\sim10\%$. A planet on an eccentric orbit ($e = 0.1$) presents a similar variability amplitude, but concentrated on a well-defined periodicity of half the orbital period and weaker broad-band noise, potentially allowing observations to discriminate between both cases. Finally, we find that the heating of the co-orbital region by the planet feedback alters the gas dynamics, reducing the difference between its orbital velocity and the Keplerian motion at the edge of the gap, which can have important consequences for the formation of dust rings.
#183 |
Three-Dimensional Modeling of Supersonic Gas Accretion and Ionized Envelope Dynamics in Jupiter-like Planets
Matias Montesinos
1
;
Juan Garrido-Deutelmoser
2
;
Nicolas Cuello
3
;
Jorge Cuadra
4
;
Amelia Ballo
5
;
Johan Olofsson
6
;
Matthias Schreiber
7
;
Mario Sucerquia
8
;
María Paula Ronco
9
;
Octavio Guilera
9
1 - Escuela de Ciencias, Universidad Viña del Mar.
2 - Instituto de Astrofísica, Pontificia Universidad Católica de Chile,.
3 - Univ. Grenoble Alpes, CNRS, IPAG,.
4 - Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez.
5 - European Southern Observatory.
6 - Max Planck Institute for Astronomy.
7 - Departamento de Física, Universidad Técnica Federico Santa María.
8 - Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso.
9 - Instituto de Astrofísica de La Plata.
Resumo:
We examine the essential dynamics and thermodynamics underlying gas giant accretion processes. By using high-performance three-dimensional hydrodynamical simulations, we model a Jupiter-mass planet embedded within a viscous gaseous disk. Our methodology incorporates a non-isothermal energy equation, enabling accurate computation of gas and radiative energy diffusion. We further introduce a radiative feedback term, which encapsulates the intrinsic luminosity of the planet, in our computational framework.
Our findings reveal the formation of an ionized envelope due to supersonic gas falling towards the planet, extending from 0.2 to 0.5 Hill radii near the planet. This envelope's radius, termed the 'ionization radius', demarcates a transition zone from pre-shock to shock regions, effectively establishing an accretion radius coinciding with the stopping radius. Notably, the stopping radius dictates the envelope's geometrical attributes.
The study underscores a robust linear relationship between the planet's accretion rate and the shock luminosity emanating from this region, with conditions propitious for H alpha emission present within the envelope. H alpha emission is an important accretion tracer to detect forming planets; however, the physical conditions near the planet remain controversial.
Importantly, our simulations show that the planet's radiative feedback reduces the velocity of the falling gas at higher altitudes ($\sim R_{\rm Hill}$), while simultaneously increasing the accretion rate within the ionization radius. This interaction promotes a 'fallback rate' towards the planet, culminating in enhanced shock luminosity. This research contributes to a better understanding of gas giant accretion's fundamental thermodynamic and dynamical properties, thereby carrying significant implications for detecting forming planets.
#210 |
Resonant Dynamics of Small Satellites and Particles in the Inner Saturnian System
Nelson Callegari Júnior
1
1 - Instituto de Geocências e Ciências Exatas - Unesp.
Resumo:
The Cassini-Huygens spacecraft took images of the last discovered Saturnian close-in small satellites. Having mean diameters d < 8 km and located in the regions of the ring system, they are Daphins (d=7.8 km), Pallene (d=4.4 km), Methone (d=3.2 km), Anthe (d=1.8 km), Aegaeon (d=0.7 km), S/2009 S 1 (d=0.3 km). The orbits of these small moons suffer complex gravitational perturbations of the non-central field of Saturn and the mid-sized satellites like Mimas. Some of these disturbances are resonant ones and contribute to their orbits' long-term stability. Additionally, all of them are involved gravitationally with the main rings, ring arcs, or diffuse rings.
In this talk, we first review the last results in the literature on the orbital dynamics of these small bodies with emphasis on mean-motion resonances and secular perturbations. Next, we show how the resonances play a role in the satellites' survival in long-term time scales of million years. Finally, we apply all these results critically discussing the evolution of the satellites and their rings counterparts after their formation.
#429 |
In search of the “Missing Mass”: Measuring Protoplanetary Disk Dust Masses with ALMA
Luisa Zamudio
1
;
Catherine Espaillat
2
;
Álvaro Ribas
3
;
Enrique Macias
4
;
Jesús Hernández
5
1 - Boston University.
2 - Institute for Astrophysical Research, Boston University.
3 - Institute of Astronomy, University of Cambridge.
4 - European Southern Observatory.
5 - Instituto de Astronomía, Universidad Nacional Autónoma de México.
Resumo:
Protoplanetary disks are an essential component of the planet formation process. The number and size of planets in a system are directly constrained by the amount of dust and gas in the disk. We present disk dust masses measured using spectral energy distribution (SED) modeling of ~50 disks around T Tauri stars (TTS) in the Serpens star-forming region, including ALMA 1.33mm fluxes from the literature. The disk masses that we calculate are a factor of ~2 higher than those reported in the literature. We find that this is because most works assume that the disk is optically thin at all mm wavelengths whereas our modeling finds that disks may be partially optically thick at mm wavelengths. Our results show that disks around TTS may have enough material to form planetary systems and could help alleviate the "missing" mass problem where there has been a reported discrepancy between the available mass in protoplanetary disks and the observable mass in observed exoplanet systems.
