terça-feira 28 de novembro
SALÓN DORADO (120)
10:20 - 11:00
COFFEE BREAK
11:00 - 12:30
H: ISM and Local Universe
ISM, Milky Way
Chair: Luis Aguilar
#073 |
The MUSE view on the Sculptor: a detailed study of the ionized interstellar medium in NGC 253
Resumo:
Galaxy evolution and star formation are tightly intertwined. However, star formation is a local process, acting on single H II regions and molecular clouds ($\sim$ 10 pc); how it can have affect galactic properties on kcp scales and drive their evolution is still one of the key open questions in astronomy. Multiwavelength observations of galaxies that can resolve the key actors in the star formation process (e.g. molecular clouds, star-forming regions, young clusters) while keeping the view of galaxies as a whole are key to understand the interplay between such small scale process and its large scale effects.
In this talk, I will present a new MUSE survey of the closest starburst galaxy to the Milky Way: NGC 253. The survey covers a total area of 20$\times$5 arcmin$^2$ (20$\times$5 kpc$^2$ at the distance of the galaxy, 3.5 Mpc) at a resolution of $\sim$15 pc, giving us a detailed view of the galactic interstellar medium that is only second to what is possible in the Milky Way and a handful of other extremely nearby objects. At the same time, the external point of view allowed us to cover the entire extension of the star-forming disk. Preliminary results show that the mosaic, which is the largest contiguous mosaic ever observed by MUSE so far, includes $\sim$6500 ionized nebulae that will be instrumental to investigate topics, among others, like the ionization and temperature structure of HII regions, the small and large scale effects of stellar feedback, and the local and galactic scale matter cycle.
#478 |
Tracing Dark Matter Halo Wakes with Stellar Halos
Chervin Laporte
1
;
Nicolas Garavito-Camargo
2
;
João Amarante
1
1 - University of Barcelona.
2 - Flatiron Institute CCA.
Resumo:
The recent infall of the Large Magellanic Cloud (LMC) onto the Milky Way provides us a unique opportunity to observe dynamical friction in action and trace large scale dark matter halo (DM) distortions in the Galaxy through observations of the stellar halo. The DM halo wake induced by the LMC's infall is thought to extend between 50 kpc all the way to the virial radius, a region still poorly explored due to the paucity of tracers at large distances. Currently, all predictions of the Milky Way's DM halo wake have relied on the poor/simplifying assumption of a smooth stellar halo, which is clearly broken beyond 30 kpc where the stellar halo is primarily constituted of substructure and non-phase mixed stellar debris. Any hope of detecting the global DM halo wake of the MW thus relies on a careful identification of known stellar debris beyond 50 kpc and models taking into account the non-smooth nature of galactic stellar halos. In this contribution, I present the first predictions of the response of a statistical sample of Galactic stellar halos formed through hierarchical accretions reacting to the DM halo wake induced by the LMC on a first infall. I will present full-sky maps in kinematic, density space of the stellar halo in the presence/absence of the LMC and how these can be used to probe large-scale DM halo distortions. Furthermore, I will show that the LMC induces remarkably pronounced isophotal twisting of the entire Galactic stellar halo in the orbital plane of the LMC, tracing the global DM halo wake, a signature awaiting detection with LSST and EUCLID. Finally, I will present a recent fully probabilistic analysis of the stellar halo using BHBs in DECaLS which successfully discerns the local wake behind the LMC but with no conclusive signs of a global wake.
#276 |
Keeping track of nearly a hundred stellar streams in the Milky Way: the galstreams library
Cecilia Mateu
1
1 - Facultad de Ciencias, Universidad de la República, Uruguay.
Resumo:
Stellar streams play in dynamics a similar role as stellar clusters do in stellar evolution: they are relatively simple systems of stars whose common properties allow rewinding evolutionary or dynamical processes much harder to disentangle in the Galactic field. Formed as stars are stripped from a dwarf galaxy or globular cluster by the Milky Way’s tidal forces, stellar streams are fossil records of accretion that are best preserved in the halo, where streams are long lived. Unearthing this record is essential to reconstructing the Galaxy’s accretion history, and modeling its dynamics is key to constrain the distribution of dark matter at the scales of the Galaxy and its satellites. In this contribution I will showcase the latest version of the galstreams library, a compilation that collates information scattered across the literature for nearly a hundred stellar streams known in the Milky Way, and use it to provide an ensemble view of the Galactic system of stellar streams’s properties, its current observational biases, and results inspired by recent discoveries made possible by the Gaia mission.
#346 |
Systematic census of RR Lyrae in cluster vs. tails of stellar streams with an associated cluster
Bruno Domínguez
1
;
Cecilia Mateu
1
;
Pau Ramos
2
1 - Universidad de la República.
2 - National Astronomical Observatory of Japan.
Resumo:
Currently it is known that galaxies like ours have formed gradually, progressively assimilating smaller galaxies. These accretion events have left fossil records that can be discovered by studying the most ancient populations such as the Galactic halo.\\
An important part of this fossil record are the globular clusters and stellar streams present in the halo. Studies have revealed that a large number of globular clusters fell into the Milky Way along with their respective host galaxies. But, these are only the “surviving” clusters. During the accretion process, clusters and dwarf galaxies can be disrupted in the halo thanks to tidal forces, generating stellar streams. Almost one hundred streams are known in the Galaxy today, most of them produced by globular clusters.\\
Our general aim is to search for RR Lyrae associated to all known stellar streams. The RR Lyrae are horizontal branch pulsating stars known for being standard candles, in this way we can obtain precise distances of the stars being able to determine the distance gradient of the stellar stream. This will be needed to determine its dynamic properties.\\
In a first exploration for the Pal5 stellar stream 10 RR Lyrae were found in the cluster and 17 in the tails; in the M68-Fjorm stream the opposite is found, while there are over 40 RR Lyrae in the cluster, only less than a handful are found in the tails. Furthermore, in the case of Pal5 the RR Lyrae are segregated: The majority of the RRc (8/12) are in the cluster while the majority of the RRab (13/15) are in the tails. In this talk we will present the first results of a systematic census of RR Lyrae in the cluster vs. the tails of the streams with an associated cluster.
#452 |
Red Clump stars and reddening law towards the Nuclear Bulge of the Milky Way
Álvaro Valenzuela Navarro
1
;
Manuela Zoccali
1
;
Elena Valenti
2
;
Rodrigo Contreras Ramos
1
;
Carme Gallart
3
;
Claudio Salvo
4
;
Julio Olivares Carvajal
1
1 - Pontificia Universidad Católica de Chile / Instituto Milenio de Astrofísica.
2 - European Southern Observatory.
3 - Instituto de Astrofísica de Canarias / Universidad de La Laguna.
4 - Pontificia Universidad Católica de Chile.
Resumo:
The Nuclear Bulge is a unique region of the Milky Way, located in the innermost ~220 pc of our Galaxy. Here, both gas structures -i.e. Central Molecular Zone, CMZ- and stellar components -i.e. Nuclear Stellar Disc, NSD- coexist. While the CMZ has been extensively studied in radio/sub-mm, the NSD lacks comprehensive observational studies. This is due to a combination of severe extinction and crowding when observing stars. In this context, Red Clump stars (RC) studies in near infrared (NIR) are the ideal structure tracers. In this talk, I will review the importance of the Nuclear Bulge for the entire Galaxy, and present the HAWK-I@VLT deep NIR high-quality photometry study of RC stars. Given the degeneracy of distance and extinction, we employ the shape of the RC to constrain the line-of-sight (LOS) distribution and the extinction law simultaneously. We obtained a set of feasible extinction laws in this particular region, along with different LOS distributions of RC stars. These results are key for further computation of the star formation history of the Nuclear Bulge, and to improve our understanding of the interaction of all structures lying here.
#480 |
An experiment in near field cosmology: Characterization of the stellar counterpart of the Magellanic wake
Manuel Cavieres
1
;
Julio Chaname
1
1 - Pontificia Universidad Catolica de Chile.
Resumo:
Gravitational interactions between the Large Magellanic Cloud (LMC) and the outer halo of the Milky Way are expected to generate a large-scale asymmetry that spans the northern Galactic hemisphere (collective response), along with a localized wake that trails the LMC's orbit. These predicted phenomena present opportunities to gain insights into the Milky Way's mass and the distribution of dark matter within its outer halo. A previous study using Gaia Early Data Release 3 and WISE surveys reported the detection of both the collective response and the wake. However, the low number statistics of the wake detection hampered an in-depth characterization of the densities involved.
In our study, we leverage deep near-infrared and optical photometry from the VISTA and DECam instruments allowing for a clean sample of halo stars that reach the oldest main sequence turnoffs at 100 kpc. Preliminary results using near-main sequence turn-off photometric distances show that the Magellanic Wake is present in our data with enough stars in the outer halo (~ 600 sources further than 60 kpc) for the detection to be considered statistically significant. This research provides us with the required data to characterize the density and position of the wake which will provide a point of comparison and constraints to simulations.
12:30 - 14:30
LUNCH
16:20 - 17:00
COFFEE BREAK
17:00 - 18:00
H: ISM and Local Universe
Milky Way
Chair: Dante Minnitti
#354 |
Where are the super metal-rich Bulge globular clusters? Revealing an inconsistency
Elisa Rita Garro
1
;
Dante Minniti
2
;
José Fernández-Trincado
3
1 - ESO.
2 - UNAB.
3 - UCN.
Resumo:
Many globular clusters (GCs) in the Milky Way (MW) have been studied in recent years, especially in hidden regions, like the MW bulge. We want to understand what we can learn if we include these new objects into the MWGC system that we know today. We catalogue 45 recently discovered GCs.
We use metallicity distribution (MD), luminosity function (LF), age distribution, and [Mg/Fe]-[Fe/H] diagram for investigating the Galactic bulge GC system. We consider 3 samples: new GCs, known and well-characterized GCs and a merging of these two samples.
We find a double-peaked distribution for the LF and MDs. We also construct the MD for the field star sample, and comparing this with that one of the GCs, we learn that a high percentage of field stars show [Fe/H]>0, whereas we do not detect any GCs in the same metallicity range. Therefore, we construct the age-metallicity diagram for both samples, noting that the old and metal-poor population is represented by GCs, while the young and metal-rich population corresponds to field stars. We build up the [Mg/Fe]-[Fe/H] diagram for known GCs and field stars, finding that the GCs are formed during the initial burst. The most metal-rich GCs seem to be the outcome of a violent and bursty star formation in the bulge or from an accreted metal-rich elliptical galaxy.
We conclude that the bimodal distribution of GCLF suggests that many GCs have been accreted during past merging events. This is also supported by the MD, which indicates that the metal-poor component is mainly the contribution due to the tidal disruption of dwarf-like objects whereas the metal-rich population is related to the formation of the bulge and/or disk. The difference that we notice between the cluster and field star samples should be sought in the evolutionary difference between these two stellar populations.
#084 |
Structure, kinematics and time evolution of the Galactic Warp revealed by
Classical Cepheids
Mauro Cabrera
1
;
Cecilia Mateu
1
;
Pau Ramos
2
;
Mercè Romero-Gómez
3
;
Teresa Antoja
3
;
Luis Aguilar
4
1 - Departamento de Astronomía, Instituto de Física, Universidad de la República, Iguá 4225, CP 11400 Montevideo, Uruguay.
2 - National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588, Japan.
3 - Institut de Ciències del Cosmos, Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, E-08028 Barcelona, Spain.
4 - Instituto de Astronomía, Universidad Nacional Autonóma de México, Apdo. Postal 877, Ensenada, 22800 Baja California, Mexico.
Resumo:
The warp is a well-known undulation of the Milky Way disc. Its structure has been widely studied, but only since Gaia DR2 has it been possible to reveal its kinematic signature beyond the solar neighbourhood. In this work we will present an analysis of the warp's structure by means of a Fourier decomposition in vertical high ($Z$) and vertical velocity ($V_z$) traced by Cepheids. We find a clear but complex signal that in both variables reveals an asymmetrical warp. In $Z$ we find the warp to be almost symmetric in amplitude at the disc's outskirts but with the two extremes never being diametrically opposed at any radius and the line of nodes presenting a twist in the direction of stellar rotation for $R>11$ kpc. In $V_z$ an $m=2$ mode is needed to represent the kinematic signal of the warp, reflecting its azimuthal asymmetry. We also find that the line of maximum vertical velocity is similarly twisted but does not overlap with the line of nodes, it trails behind by $\approx 25$ deg. We will show how the twisted line of maximum $V_z$ creates "arches" in the mean $V_z$ as a function of radii, a signature of global warp kinematics that has been observed with other tracers with less azimuthal coverage of the disc. Finally, a joint analysis of the Fourier decompositions in $Z$ and $V_z$ allows us to develop a new model-independent formalism to derive the pattern speed and change in amplitude of each mode at each radii. By applying it to our results for the Cepheids we find, for the $m=1$ mode, a constant pattern speed in the direction of stellar rotation of $9.18$ km/s/kpc, a constant amplitude up to $R\approx 14$ kpc and a slight increase in amplitude at larger radii, in agreement with previous works.
#441 |
All-sky Kinematics and Chemistry of Monoceros Stellar Overdensity
Lais Borbolato
1
;
Hélio D. Perottoni
2
;
Silvia Rossi
1
;
Guilherme Limberg
1
;
Angeles Pérez-Villegas
3
;
Friedrich Anders
4
;
Teresa Antoja
4
;
Chervin F. P. Laporte
4
;
Helio J. Rocha-Pinto
5
;
Rafael M. Santucci
6
1 - Universidade de São Paulo.
2 - Polish Academy of Sciences.
3 - Universidad Nacional Autónoma de México.
4 - Universitat de Barcelona.
5 - Universidade Federal do Rio de Janeiro.
6 - Universidade Federal de Goiás.
Resumo:
We use a combination of data from 2MASS, WISE, APOGEE, and Gaia DR3 to study the kinematic and chemical properties of Monoceros' stellar overdensity. Monoceros is a structure located towards the Galactic anticenter and close to the Galactic plane. We identified that its stars have azimuthal velocity in the range of 200 < v(phi) (km/s) < 250. Combining their kinematics and spatial distribution, we designed a new method to select stars from this overdensity. This method allows us to easily identify the structure in both hemispheres and estimate their distances. Furthermore, we characterized, for the first time, the Monoceros overdensity in several chemical-abundance spaces. Our results demonstrate that the southern (Mon-S) and northern (Mon-N) regions of Monoceros exhibit indistinguishable chemical compositions, and we also confirm their resemblance to stars found in the thin disk of the Galaxy and suggesting an in situ formation.
18:00 - 18:30
G: Stars and Stellar Physics
Stellar Populations
Chair: Dante Minnitti
#321 |
The Metallicity Gradient of Sagittarius Dwarf Spheroidal Galaxy Prior to Infall Constrained by S-PLUS Observations of its Tidal Stream
Felipe Almeida-Fernandes
1
;
Guilherme Limberg
1
;
Helio Perottoni
2
;
Joao Amarante
3
;
Pierre Martho
1
;
Eduardo Pereira
4
;
Gabriel Fabiano de Souza
1
;
Guilherme Bolutavicius
1
;
Rafael Santucci
5
;
Silvia Rossi
1
;
Marcos Vinicius Cordeiro da Silva
4
;
Marcelo Borges
4
;
Vinicius Placco
6
;
Claudia Mendes de Oliveira
1
1 - Universidade de Sao Paulo.
2 - Nicolaus Copernicus Astronomical Center.
3 - Institut de Ciencies del Cosmos - Universitat de Barcelona.
4 - Observatorio Nacional.
5 - Universidade Federal de Goias.
6 - NOIRLAB.
Resumo:
Several major substructures, like the Sagittarius stream, have been observed in the Milky Way halo over the past few years. These substructures are likely remnants of past accretion events, therefore, investigating their origin and nature is crucial to understanding the formation and evolution of our Galaxy in the context of hierarchical galactic formation. In this study, we used photometric metallicities to study the current metallicity gradient in the arms of the Sagittarius stream, and compared these results to predictions of N-body simulations to reconstruct the original metallicity gradient in the Sagittarius dwarf galaxy prior to its accretion by the Milky Way. To build our sample, we did a cross-match between S-PLUS DR4 photometry and a list of Sagittarius stream members, available in the literature, which were selected using astrometric data from Gaia DR3. We applied two different techniques to estimate photometric metallicities: an artificial neural network and a random-forest algorithm, resulting in two samples of, respectively, 7398 and 4683 stars with reliable metallicity measurements. We measured a gradient of $\approx -0.0030$ dex/degree for the leading arm of the stream. For the trailing arm, we found no significant gradient when considering the whole area covered by S-PLUS ($20 \leq \Lambda \leq 130$ degrees), but the region near the core ($20 \leq \Lambda \leq 70$ degrees) also present a gradient of $\approx -0.0035$ dex/degree. We imprinted artificial metallicities to particles in a N-body simulation of the stream, available in the literature, considering different scenarios of original metallicity gradients. Comparing simulated and observed results, we were able to show that the current metallicity gradient in the stream is consistent with an original metallicity gradient between $-0.22$ and $-0.37$ dex/kpc in the Sagittarius progenitor galaxy.
#503 |
Unveiling Galactic Secrets: Chemical Tagging of Milky Way Variable Stars with SPLUS
Debasish Hazarika
1
;
Carlos E. Ferreira Lopes
1
1 - Institute of Astronomy and Planetary Sciences, University of Atacama, Chile.
Resumo:
We present the chemical tagging analysis of over 35,000 variables within the Milky Way, classified using the unique multiwavelength 12-bands photometric observational data from the ongoing Southern Photometric Local Universe Survey (S-PLUS). Leveraging the chemical and elemental information of individual stars as training set from spectroscopic surveys such as LAMOST and APOGEE, we utilize machine learning models to predict the chemical abundances ([Fe/H], [Alpha/H], [Ca/Fe], [C/Fe], [Mg/Fe], [Si/Fe], [Ni/Fe], [Na/Fe]) of individual stars in the S-PLUS based on their photometric colors. Additionally, the information on radial velocity and proper motion from RAVE \\& GAIA along with the predicted chemical abundances helps us accurately position the variables in the Milky Way and facilitate the separation of galactic components such as thin, thick disks, halo etc., based on multiple spatial aspects in the positional, chemical, and dynamical space, which is crucial for deriving new insights about the structure and kinematics of our galaxy.
#560 |
An internal view of Stellar system Terzan 5
Francesco Mauro
1
;
Vanessa Gotta
1
;
Christian Moni Bidin
1
;
Doug Geisler
2
;
Francesco Ferraro
3
1 - Instituto de Astronomia, Universidad catolica del Norte.
2 - Departamento de astronomia, Universidad La Serena.
3 - Department of Physics and Astronomy, University of Bologna.
Resumo:
We present the spacial-photometric analysis of the inner part of the interesting globular cluster Terzan 5 using observed with GeMS/GSAOI and HST. Terzan 5 is one of the most massive globular cluster of the Milky Way localized near the center of the Galactic bulge. It is characterized by a double horizontal branch, due to two stellar population that show a substantial difference in age and metallicity (~7Ga and 0.5 dex, respectively); for this reason Terzan 5 is thought to be one of few remaining building blocks of the Galactic Bulge, together with Liller1. In this work we analyze the populations of Terzan 5 determine their spatial distributions, the fundamental parameters of the stellar system.
