Seminars and Colloquia at ESO Santiago

March 2024

28/03/24 (Thursday)
15:00, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Variable mass loss on 100 yr timescales from massive yellow hypergiants
Evgenia Koumpia (ESO)

Abstract

The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss rate and geometry. The geometry of the mass-loss process can be inferred from the shape of the circumstellar material, having a significant influence on the evolution of massive stars (25 and 40 Msun), i.e., type II SN progenitors. In this context, yellow hypergiants (YHGs) offer an excellent opportunity to study mass-loss events.

This talk will focus on recent results on two members of this class, IRAS 17163-3907, the central star of the Fried Egg nebula and IRC +10420. I will present the analysis of optical and near-infrared data with the main focus on the observed spectroscopic and interferometric (GRAVITY/VLTI) modes. Our VLTI/GRAVITY K-band interferometry on both sources reveals that the neutral Na I 2.2 μm line emitting region is smaller than that of the hydrogen Brγ emission. We perform LTE modelling demonstrating that this observation can be explained with the hydrogen emission being the result of collisional excitation populating the higher levels in a neutral region instead them being populated through recombination in an ionised environment as mostly inferred in stellar winds. In addition, our geometric models towards IRC+10420, reveal an evolution of the ejecta over only about 7 years, while our 2D radiative transfer modelling towards IRAS 17163-3907 led to the discovery of a third hot inner shell with a maximum dynamical age of only 30 yr. For this yellow hypergiant, we find three observed distinct mass-loss episodes which are characterised by different mass-loss rates and can inform theories of mass-loss mechanisms, which is a topic still under debate both in theory and observations. These will be discussed in the context of photospheric pulsations and wind bi-stability mechanisms.

April 2024

02/04/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
03/04/24 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Exploring satellite group infall into the Milky Way: the case of the Crater-Leo objects
Mariana P. Júlio (Leibniz-Institut für Astrophysik Potsdam (AIP))

Abstract

Within Λ Cold Dark Matter simulations, Milky Way-like galaxies accrete part of their satellite galaxies in small groups rather than individually. It was suggested that this might be the reason behind the origin of satellite planes and the galaxy pairs found in the Local Group, providing new insights on dwarf galaxy formation and evolution. 

Objects accreted in groups are expected to share similar specific total energy and angular momentum, and also identical orbital orientations. Looking at observations of Milky Way satellites, the dwarfs Leo II, IV, V, Crater II, and the star cluster Crater 1 were proposed to be a vestige of group infall. The suggested "Crater-Leo group" shows a monotonic distance gradient and all these objects align along a great circle.

To further investigate this possibility, we use Gaia Data Release 3 and present new Hubble Space Telescope (HST) proper motions to derive accurate orbital properties for these objects. Assuming that satellites accreted as a group share similar specific angular momentum and total energy, we can identify possible associations and predict their proper motions.

Leo II, Leo IV, and Crater 1 show orbital properties consistent with those we predict from assuming group infall. However, our results suggest that Crater II was not accreted with the rest of the objects. If confirmed with increasingly accurate proper motions in the future, the Crater-Leo objects appear to constitute the first identified case of a cosmologically expected, typical group infall event.

04/04/24 (Thursday)
15:00, Vitacura | ESO Santiago
TMT (30 minutes talk)
Talk — Magnetic Horrors: challenges of the spectroscopic analysis of young stars
Martina Baratella (European Southern Observatory (ESO))

Abstract

Several recent studies have proven that the high-resolution spectroscopic analysis of young (t< 200 Myr) solar-analogues is rather complicated. The main culprit is activity, which presents in an intricate combination of relatively intense magnetic fields, presence of dark and bright spots on the surface and high levels of variability. All these contribute with significant variations of the strength (i.e., the equivalent width) of the atomic spectral lines, dramatically affecting, among other things, the derivation of the stellar parameters (mainly microturbulence velocity parameter) and the abundances of some elements (for example, barium and carbon). The times are now ripe to discuss and finally address these issues, given the importance of a precise stellar characterization for exoplanetary studies and to correctly interpret Galactic abundance trends. In this talk, I will revise our group's latest results in the spectroscopic analysis of young stars, presenting innovative techniques developed using stars in Galactic open clusters and new work(s) in progress.

09/04/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Modelling the optical to mid-infrared nebular spectra of Type Ia supernovae
Stéphane Blondin (Laboratoire d'Astrophysique de Marseille)

Abstract

The first JWST observations of Type Ia supernovae (SN Ia) in the nebular phase have paved the way for late-time studies covering the full optical to the mid-infrared range, and with it the hope to better constrain SN Ia explosion mechanisms. I will present the results of 1D non-LTE radiative-transfer simulations performed with CMFGEN based on a variety of explosion models available in the Heidelberg Supernova Model Archive (HESMA), including Chandrasekhar-mass (MCh) delayed detonations, sub-MCh double detonations, and violent double White Dwarf mergers. I will 
discuss the impact of ejecta asymmetries and ionisation effects on the predicted spectra, and highlight uncertainties in the atomic data commonly used for forbidden lines. These models suggest that key physical ingredients are missing from either the explosion models, or the radiative-transfer post-processing, or both. Nonetheless, they also show the potential of the near- and mid-infrared to uncover new spectroscopic diagnostics of SN Ia explosion mechanisms.
11/04/24 (Thursday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — TBD
Paul Cristofari (CfA (Harvard))

Abstract

TBD

16/04/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
17/04/24 (Wednesday)
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — The chemical characterisation of young protostars: the crucial role of cm observations
Marta de Simone (ESO Garching)

Abstract

TBD

18/04/24 (Thursday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — TBD
Vlad Răstău

Abstract

TBD

23/04/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
24/04/24 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — The origins of ~70% of meteorites and of the first mass extinction event
Michaël Marsset (ESO)
25/04/24 (Thursday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — tbd
Oleg Egorov (Zentrum für Astronomie Heidelberg)

Abstract

tbd

29/04/24 (Monday)
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — tbd
Evgeniya Egorova (Heidelberg)

Abstract

tbd

30/04/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — TBD
Alessandro de Angelis

Abstract

TBD

May 2024

06/05/24 (Monday)
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — tbd
Linn Eriksson (Stony Brook)

Abstract

tbd

07/05/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
15:30, Library (ESO, Vitacura) | ESO Santiago
TMT (30 minutes talk)
Talk — tbd
Eric Andersson (AMNH)

Abstract

tbd

08/05/24 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
TMT (30 minutes talk)
Talk — Interferometric observations of star l Puppis
Margaux ABELLO (LAGRANGE laboratory - Observatoire de la Côte d'Azur)

Abstract

TBD

14/05/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
15/05/24 (Wednesday)
15:30, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — TBD
MOONS Consortium (ESO Garching)

Abstract

TBD

21/05/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
23/05/24 (Thursday)
15:00, Urania room (ESO, Santiago) | ESO Santiago
ESO Colloquium
Talk — tbd
Luigi Foschini (INAF)

Abstract

tbd

28/05/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

June 2024

04/06/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
11/06/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
18/06/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
25/06/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

July 2024

02/07/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
09/07/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
11/07/24 (Thursday)
15:30, Licancabur meeting room | ESO Santiago
JAO Tech Talks
Lecture — NOEMA
Kirsty Butler (IRAM)

Abstract

TBD

16/07/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
23/07/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
30/07/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

August 2024

06/08/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
13/08/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
20/08/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
27/08/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

September 2024

03/09/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
10/09/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
17/09/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
24/09/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

October 2024

01/10/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
08/10/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
15/10/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
22/10/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
29/10/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

November 2024

05/11/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
12/11/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
19/11/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
26/11/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH

December 2024

03/12/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH
10/12/24 (Tuesday)
11:00, Miscanti room, ALMA building | ESO Santiago
JAO/ESO Astro-ph
Meeting — AstroPH