Thursday 30 de November
SALÓN AZUL
09:00 - 09:50
Plenary Review Talk
Invited Speaker:
Ingrid Pelisoli
- University of Warwick
(UK)
[cv]
Ingrid Pelisoli
University of Warwick
Curriculum Vitae:
Dr Ingrid Pelisoli is originally from Brazil, where she obtained a PhD from the Federal University of Rio Grande do Sul. After completing her PhD, she was a Postdoctoral Research Fellow at the University of Potsdam, in Germany. She joined her current institution, the University of Warwick (UK), in 2020 as a Research Fellow. Her main research interests are white dwarf and hot subdwarf stars. She focuses in particular on systems that have been affected by binary interaction, seeking to provide observational input for modelling binary phenomena such as Type Ia supernova and gravitational waves. She is a member and former Quality Control Scientist of the 4-metre Multi-Object Spectroscopic Telescope (4MOST) survey, and of the BlackGEM consortium.
Chair: Melina Bernsten
#110 |
Binarity is all around us: searching and characterising the late stages of binary evolution
Ingrid Pelisoli
1
1 - University of Warwick.
Abstract:
About a third of stars are in binaries, and yet our understanding of how binarity affects stellar evolution is still fragmentary and only qualitative in many aspects. From gravitational waves to supernova Ia explosions, binary interaction plays a crucial role in our comprehension of the Universe. In order to improve our modelling of the many pathways of binary evolution, observational input is required. In this talk, I will discuss the effects of binarity in stellar evolution and their observational signatures. I will talk about current challenges in modelling binary systems and how the detailed characterisation of nearby populations can provide valuable input for theoretical models.
09:50 - 10:20
Plenary Target Talk
Invited Speaker:
Denise R. Gonçalves
- Observatório do Valongo, Universidade Federal do Rio de Janeiro
(Brasil)
[cv]
Denise R. Gonçalves
Observatório do Valongo, Universidade Federal do Rio de Janeiro
Curriculum Vitae:
Graduated in Physics from UFPR, she holds a master’s and doctorate in Astronomy from USP. As a postdoctoral fellow and visiting researcher, she conducted research at institutions such as: Instituto de Astrofísica de Canarias; University College London; ALMA Group of the National Astronomical Observatory of Japan. She is currently a member of the IAU as well as of the international surveys S-PLUS, J-PLUS and J-PAS, in which she coordinates projects for the discovery of new planetary and symbiotic nebulae. She is responsible for the Gemini RAMSES II project that counts symbiotic stars in dwarf galaxies. Since 2022, she holds the FAPERJ’s Thematic and Scientist of Our State prestigious grants. She is a CNPq productivity fellow and associate professor at the Valongo Observatory (UFRJ) – being responsible for the research group Photoionized Nebulae. Her work emphasizes the final phases of stellar evolution – planetary and symbiotic nebulae – and the chemical evolution of the local Universe.
Chair: Melina Bernsten
#472 |
HUNTRESS: HUnting plaNeTaRy nEbula and Symbiotic Stars
Denise R. Gonçalves
1
1 - Valongo Observatory - Federal University of Rio de Janeiro.
Abstract:
Planetary nebulae (PNe) and symbiotic stars (SySt) are fascinating objects related to the fate of the great majority of stars in any galaxy. PNe are bubbles of ionized gas, produced from low- and intermediate-mass stars towards their latest life stages. Approximately 3,500 PNe have been identified in the Milky Way, but only 14 in the Galactic halo. Halo PNe are relevant because they provide clues about the final evolution of old, low-mass stars and they are able to convey fundamental information of the early chemical conditions of the Galaxy, including its star formation history. SySt are binary systems formed by evolved stars: a cool giant star and a hot star (usually a white dwarf). Their crucial role in Astrophysics resides on the fact they allow the study of the mechanisms behind supersoft X-ray sources, thermonuclear outbursts, collimation of stellar winds and jets or the shaping of other nebulae, like of PNe. Moreover, being binary systems that contain at least one degenerated star, SySt are also possible progenitors of Type Ia supernovae, key for the cosmological distance scale. Living in an era of gigantic multi-band optical photometric surveys, as VPHAS+, J-PLUS, S-PLUS and the forthcoming J-PAS, our group is member of the last three of these projects, and each of them will map ~8,000$^2$ of either the north (J-PLUS and J-PAS) or the south (S-PLUS) sky. Adding to these surveys, RAMSES II is an international Gemini project to map the Local Group dwarf galaxies using an emission-line that is unique to identify SySt. We take advantage of these projects to comprise a big effort aimed at discovering PNe and SySt based on VPHAS+, J-PLUS, S-PLUS, J-PAS and RAMSES II. This talk will discuss the results so far obtained from this enterprise.
10:20 - 11:00
COFFEE BREAK
11:00 - 12:15
G: Stars and Stellar Physics
Binary Evolution and binary systems
Chair: Julio Chanamé
#351 |
Understanding the Impact of Binary Transfer in the Accretor$^\prime$s Measurable Parameters
Magdalena Vilaxa
1
;
Nathan Leigh
1
;
Taeho Ryu
2
1 - Universidad de Concepción.
2 - Max Planck Institute for Astrophysics.
Abstract:
Mass transfer in binary star systems is thought to be the main formation channel for Blue Stragglers: apparently rejuvenated main-sequence stars that lie above and to the blue of the turn-off point in a star cluster color-magnitude diagram, where single star evolution predicts a paucity of stars. But the impact of mass transfer on the accretor's observed properties has yet to be constrained. Aiming to predict the accretor's observational properties, we present an analytical model describing the aftermath of direct mass accretion in binary stars. We confront our model with hydrodynamical simulations of binary mass transfer, allowing for predictions of the observed properties of post-mass transfer accretors as a function of the progenitor binary's orbital parameters. In this talk, we present preliminary results, which quantify how the initial orbital parameters of the system shape the surface temperature and rotation of the accretor.
#383 |
On the binary origin of Blue Stragglers in Collinder 261
Maite Echeveste
1
;
María José Rain
2
;
Giovanni Carraro
3
;
Jorge Alejandro Panei
1
;
Omar Gustavo Benvenuto
1
;
María Alejandra De Vito
1
1 - Instituto de Astrofísica de La Plata, Facultad de Ciencias Astronómicas y Geofísicas UNLP.
2 - European Southern Observatory (ESO).
3 - Dipartamento di Fisica e Astronomia, Universita’ di Padova.
Abstract:
Blue-straggler stars (BSS) are peculiar objects found in various stellar systems. They exhibit characteristics of youth, higher temperature, and greater mass than expected according to standard stellar evolution. Moreover, they occupy a position above and to the left of the main sequence turn-off point in the optical color-magnitude diagrams (CMDs). The prevailing consensus is that BSS were originally main-sequence stars that acquired additional mass via mass transfer from an evolving primary star through Roche lobe overflow and/or via collisions involving single, binary, or triple stars. Based on the recent publication of a fresh catalog of BSS in Galactic Open Clusters (OC) using Gaia DR2 data (Gaia Collaboration et al. 2018), we conducted a study focusing specifically on the short-period BSS found in the OC Collinder 261. Our investigation delved into the potential of mass transfer in binary systems in accounting for the presence and properties of these stars. We used an adaptation of the binary evolution code presented in Benvenuto \\\\& De Vito (2003), which allowed us to perform comprehensive calculations on the structure of both stars within the binary system, as well as the orbital evolution and mass transfer rate simultaneously. Our investigation included the study of several parameters, such as the initial mass of both stars, the initial orbital period, and the efficiency of mass transfer. The aim is to identify potential progenitor candidates matching CMD observations at the same age as that determined for Collinder 261. We found that binary evolution serves as a viable mechanism for producing these BSS and that the efficiency of mass transfer plays a key role in accurately matching the fainter objects.
#341 |
The Local Group Symbiotic System Population and its Weak Correlation with Type Ia Supernova Events
Marco Laversveiler
1
;
Denise R. Gonçalves
1
1 - Valongo Observatory - Federal University of Rio de Janeiro.
Abstract:
Symbiotic stars (SySt) are evolved binary systems in which a white dwarf (WD) accretes mass from a giant star. This stellar configuration causes light curve variability and other phenomena like recurrent nova eruptions and jets, turning SySt good laboratories for many binary interaction phenomena. Here we deal with the problem of the SySt population and its controversial relation with type Ia supernovae (SNe Ia) in the galaxies of the Local Group. Since a fraction of the WDs can be massive ($>$ 1 M$_\odot$) in some SySt, accretion might be enough to reach the Chandrasekar mass. Due to this condition, SySt have been considered as potential SNe Ia progenitors. This contribution is an attempt to pave the SySt-SN Ia relation adopting two approaches: an empirical, based on the distribution and dynamics of the SySt in the Galaxy; and a statistical that applies to the Galaxy and dwarf galaxies in the Local Group. Per galaxy, the main parameters involved are the initial mass function, the zero age main sequence binary system’s semi-major axis and mass ratio distributions, the binary fraction and the mean metallicity. Our results show an estimated Galactic SySt population ranging from the minimum empirical threshold value of $\sim 10^3$ to an expected statistical amount of $\sim 2\text{--}4 \times 10^4$. For Local Group dwarfs galaxies, the expected SySt population ranges from 2 to 4 orders of magnitudes lower, depending mainly on the galaxies’ bolometric luminosity. Concerning the SNe Ia events, we show that SySt are not the main progenitors. Either way, we infer that it is still expected that a few percent of the SNe Ia might have symbiotic progenitors in the Milky Way, while the majority of the – low-luminosity – dwarfs galaxies did not experience symbiotic type Ia supernovae.
#567 |
Blue Straggler Stars in Open Clusters
Maria Jose Rain
1
1 - European Southern Observatory.
Abstract:
Blue straggler stars (BSS) are exotic objects that are present in all stellar environments, but their nature and formation channels are still partially unknown. This work presents an observational and theoretical effort made to contribute to a better understanding of the properties of BSS in open clusters (OCs), enhance membership-based BS statistics, and shed light on which formation mechanism is the most predominant from a macro scale point of view.
Two are the sides that define our work. From one side, we will present the most comprehensive and homogeneous catalog of the BSS population in a sample of more than 400 OCs, critically revisiting the relationship of the stragglers and cluster's host parameters, but also comparing them with a suite of composite evolutionary sequences derived from binary evolutionary models. From the other side, we will describe the different type of binaries we found among the straggler population, and how they relate with the different formation scenarios. By combining observational data and theoretical modeling we will show that binary evolution is the most viable scenario to form stragglers in Galactic star clusters.
#280 |
A systematic method to identify runaways from star clusters produced from single-binary interactions: A case study of M67
Alonso Herrera
1
;
Nathan Leigh
1
;
Magdalena Vilaxa
1
1 - Universidad de Concepción.
Abstract:
Runaway stars are objects observed with high velocities thought to be ejected from star clusters. There are two competing mechanisms for their production: SN-based ejections in binaries, where one companion explodes leaving no remnant and launching the other companion at the instantaneous orbital velocity, and the disintegration of triples which produces a recoiled runaway binary (RB) and a runaway star (RS), ignoring collisions which happen rarely. We examine runaway star formation in the old open cluster M67 in this work, with a focus on triple disintegration, using data from the Gaia DR3 survey. We create a systematic methodology to look for the computed number of candidate runaway pairs we expect to observe. We use our criteria to search for these pairs in a circular field of view surrounding M67, and create a catalog using our highest probability pairs. Preliminary results could reveal a number of interesting runaway star candidates for the triple disintegration scenario considered in this study, which we identify for radial-velocity follow-up.
12:30 - 14:30
LUNCH
14:30 - 15:00
Plenary Target Talk
Invited Speaker:
Aina Palau
- Instituto de Radioastronomía y Astrofísica
(México)
[cv]
Aina Palau
Instituto de Radioastronomía y Astrofísica
Curriculum Vitae:
Aina Palau Puigvert cursó la carrera de Ciencias Físicas en la Universitat de Barcelona (España) y realizó los estudios doctorales en la misma universidad en colaboración con el Harvard-Smithsonian Center for Astrophysics de Cambridge, Estados Unidos. Tras terminar su doctorado se le concedió un contrato postdoctoral en el Centro de Astrobiología de Madrid, centro asociado al NASA Astrobiology Institute, donde operaba antenas de seguimiento de satélites de la NASA. Posteriormente obtuvo una beca postdoctoral del Consejo Superior de Investigaciones Científicas en Barcelona (España) y actualmente es investigadora titular de la UNAM. Ha sido invitada a impartir conferencias en más de 15 congresos o centros de investigación nacionales o internacionales, así como a escribir capítulos de revisión. Hasta la fecha, ha publicado más de 105 artículos en las revistas arbitradas internacionales de más impacto y ha recibido más de 3100 citas en la literatura internacional. Además, ha publicado varios capítulos de libro, ha impartido más de 20 cursos en maestrías de Astrofísica, ha dirigido 9 tesis, y ha sido árbitro en prestigiosas revistas e instituciones internacionales. Finalmente, la doctora se ha preocupado intensamente durante toda su trayectoria por acercar la ciencia a la población, llevando a cabo numerosas actividades de divulgación a todos los niveles, desde pre-escolar hasta nivel universitario y público en general. En marzo de 2022, recibió el Reconocimiento Sor Juana Inés de la Cruz por parte de la UNAM, por su destacada labor en investigación, docencia y difusión de la ciencia.
Chair: Lucimara Martins
#600 |
The early stages of stellar cluster formation
Aina Palau
1
;
Qizhou Zhang
2
;
Josep M. Girart
3
;
Esmeralda Drouaillet
1
;
Junhao Liu
2
;
Patrick M. Koch
4
1 - IRyA-UNAM, Mexico.
2 - Harvard/Smithsonian Center for Astrophysics, USA.
3 - Institut de Ciencies de l$^\prime$Espai, CSIC, Spain.
4 - Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan.
Abstract:
How stellar clusters form and what determines their richness are long-standing questions, intimately related to the fragmentation properties of molecular clouds. It is thought that a number of properties such as density and temperature structure, turbulence, stellar feedback, initial angular momentum, and magnetic fields could influence the fragmentation process. We will present an observational campaign aimed at disentangling which of these properties finally control the fragmentation process in the dense parts of molecular clouds, from 0.2 pc to 1000 au scales. We will show for the first time a tentative correlation between the fragmentation level and the mass-to-magnetic flux ratio, as predicted by numerical and theoretical works. Finally, we will show ALMA data for one of the highly fragmenting regions of our sample, revealing further fragmentation down to 100 au, and unveiling that a high fraction of the continuum sources actually present emission of complex organic molecules. This suggests that the precursors of pre-biotic molecules might be more common than previously thought in this kind of environments.
15:00 - 15:30
Plenary Target Talk
Invited Speaker:
Paula Coelho
- Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo
(Brasil)
[cv]
Paula Coelho
Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo
Curriculum Vitae:
I am an associate professor at the University of Sao Paulo working with stellar populations. I did my PhD in University of Sao Paulo and spent my post-doctoral years in Europe. My research focuses on integrated stellar populations, which involves the spectral synthesis of stars and combining them into model galaxies with population synthesis methods. With models in hand I am able to do archaeological studies of stellar clusters and galaxies, i.e., to infer their past evolutionary histories from the measurements of their present-day spectra. In particular, I contributed with the spectral modelling of alpha-enhancement in old galaxies and CNONa anti-correlations in globular clusters.
Chair: Lucimara Martins
#102 |
To use or not to use model stellar spectra to study integrated stellar populations?
Paula Coelho
1
1 - Universidade de Sao Paulo.
Abstract:
Libraries of stellar spectra are fundamental tools in the study of stellar populations, among other applications. Theoretical libraries -- i.e. model stars -- have been extensively used to cover gaps left by empirical libraries, such as regions of the Kiel diagram not populated by nearby stars. Yet, they suffer from modelling inaccuracies. So should we use or not use model stars in integrated stellar populations? To study this question, we build a synthetic stellar library mimicking the coverage of an empirical library, and stellar population models tailored to these investigations. We learned that uncertainties in stellar population colours are dominated by the lack of coverage in the Kiel diagram; the effects on spectral features indices are multiple and defy simple conclusions; galaxy ages are virtually unaffected by the choice of the library, but are underestimated when libraries with limited Kiel coverage are used; metallicities are underestimated when using synthetic libraries. With current models and observation of stellar libraries, there isn't a unique answer, and the right choice will depend on the science case.
15:30 - 16:00
Plenary Target Talk
Invited Speaker:
Gisela Ortiz León
- Instituto Nacional de Astronomía Óptica y Electrónica
(México)
[cv]
Gisela Ortiz León
Instituto Nacional de Astronomía Óptica y Electrónica
Curriculum Vitae:
Gisela Ortiz León realizó estudios de Licenciatura en Física en la Facultad de Ciencias de la Universidad Nacional Autónoma de México (UNAM) y posteriormente estudios de maestría y doctorado en el Instituto de Radioastronomía y Astrofísica de la misma institución. Realizó de 2017 a 2021 una estancia posdoctoral en el Instituto Max Planck para Radioastronomía en Bonn, Alemania. Posteriormente realizó una estancia posdoctoral en el Instituto de Astronomía de la UNAM. Desde 2023 es investigadora titular en el Instituto Nacional de Astrofísica, Óptica y Electrónica. Gisela Ortiz es experta en el uso de interferómetros de larga línea de base (VLBI) para hacer estudios astrométricos de estrellas jóvenes y evolucionadas. Su línea de investigación abarca además interferometría en radio, formación estelar, caracterización de sistemas dobles de estrellas y búsqueda astrométrica de objetos sub-estelares. Ha recibido numerosos reconocimientos, entre ellos el premio por parte de la Unión Astronómica Internacional a la mejor tesis de doctorado de 2017 en la rama Astronomía Fundamental, la beca Alexander von Humboldt para investigadores postdoctorales y el Premio Breakthrough en Física Fundamental, que comparte con el Consorcio del Telescopio del Horizonte de Eventos.
Chair: Lucimara Martins
#535 |
A six dimensional view of stellar and planetary systems with high precision astrometry
Gisela Ortiz-Leon
1
1 - Instituto Nacional de Astrofísica, Óptica y Electrónica.
Abstract:
Astrometric precision of tens of micro-arseconds can provide the six-dimensional information (position and velocity) of individual members in stellar systems. While Gaia, operating at optical wavelengths provides micro-arsecond astrometry for billions of stars, at radio wavelengths one can see through the dense material of molecular clouds, reaching the youngest and most embedded stars, and thus probing the early stages of star formation. In this talk, I will present our work on using astrometry at radio wavelengths, complemented with Gaia astrometry, to study the three-dimensional structure of star-forming regions, the internal kinematics of young stellar clusters and the characterization of young multiple systems in close orbits. I will also show recent wok on radio astrometric searches for exoplanets in single and binary stars. I will show how these kind of searches complement other planet searching techniques by allowing the determination of the full orbital characteristics. This is relevant to investigate, for instance, the true alignment between the planet and binary orbits in binary systems, as well as the origin of misaligned systems.
16:00 - 16:45
COFFEE BREAK
16:45 - 18:00
ASSEMBLY
ASSEMBLY
Chair: Gonzalo Tancredi
20:00 - 23:50
CONFERENCE DINNER AND CONCERT
