| Wednesday, August 23, 2023 |
12:00pm |
Piyush Sharda, Leiden University |
The Role of Metals From Molecular Clouds to Galactic Discs
Abstract
From the time the first stars formed to the present-day, metals have witnessed the assembly of structure in the Universe in great detail. Although metals only form in stars and stellar remnants, they are ubiquitously present everywhere -- from planetary cores to the intergalactic medium. However, we still do not understand how metals are effectively dispersed throughout the Universe, and the various roles they play in shaping galaxies. In this talk, I will present a multi scale approach to study the role of metals in galaxy evolution, from molecular clouds to galactic discs. On smaller scales, I will focus on physical processes that shape up the initial mass function (IMF, with a particular emphasis on metal-free and metal-poor environments) that directly set the integrated yield of metals in the first and early galaxies. I will discuss results from high resolution chemo-magnetohydrodynamic simulations that study the impact of turbulence and magnetic fields on the primordial IMF, and describe analytical models of dusty molecular clouds that explain the transition in the IMF as the metal abundance grows over cosmic time. On larger scales, the talk will cover the physics of gas-phase metal distribution in galaxies. Using a combination of spatially-resolved gas-phase metallicity measurements and novel semi-analytical models, I will present recent results that advance our understanding of metallicity gradients in (late type) galaxies. In particular, I will show how self-consistently incorporating metal dynamics into galaxy evolution models is key to explaining the observed trends in metallicity gradients with galaxy mass, metallicity, and kinematics. I will end by highlighting how ongoing/upcoming astronomical facilities will transform our understanding of metal evolution in galaxies.
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| Wednesday, August 30, 2023 |
12:00pm |
No talk scheduled |
No talk scheduled
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| Wednesday, September 06, 2023 |
12:00pm |
Catherine Manea, The University of Texas at Austin |
Our Chemically Diverse Milky Way: The Added Dimension of Neutron-capture Elements
Abstract
The observed chemical diversity of Milky Way stars carries implications for Galactic chemical evolution, the expected diversity of exoplanetary systems in the Milky Way, and the inferred chemical distributions of unresolved stars in extragalactic systems, among other topics. Recent works have found that the chemical diversity of Milky Way stars is low. For example, the APOGEE chemical “doppelganger rate,” or the rate at which random pairs of field stars appear as chemically similar as stars born together, is high, and the chemical distributions of APOGEE stars are well-described using models with just two dimensions. However, limited attention has been paid to the heavy elements (Z > 30) in this context. In this talk, I will present our recent work using GALAH DR3 to assess the role of the neutron-capture elements in enhancing the chemical diversity of Milky Way stars. We find that the neutron-capture elements significantly reduce the doppelganger rate. Our results also suggest that the slow neutron-capture process elements may carry greater distinguishing power than the rapid neutron-capture process elements. This talk will highlight the importance of considering the neutron-capture elements when chemically characterizing stars in the Milky Way and validate ongoing work to improve their measurements in spectroscopic surveys.
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| Wednesday, September 13, 2023 |
12:00pm |
Cheng-Han Hsieh, Yale University |
The CAMPOS Legacy Survey: Evolution of disk substructures
Abstract
One of the main unsolved problems in planet formation is pinpointing the starting time for planet formation. A crucial aspect of this quest involves identifying substructures within circumstellar disks, which could serve as early indicators of planet formation. The high angular resolution observations by ALMA have been a game-changer in the field and revealed for the first-time substructures in disks with unprecedented details (eg. surveys like DSHARP & ODISEA). However, these surveys focused on more evolved Class II disks and ODISEA is limited to the Ophiuchus molecular clouds only. We present the CAMPOS Legacy survey, an ALMA survey of all embedded Class 0/I and Flat protostellar disks in the star-forming clouds of Chamaeleon, Ophiuchus, Aquila, Corona Australis, and Serpens. By probing over 90 disks down to 15 au resolution, we conducted the first statistical search for disk substructures around Class 0/I protostars. Our findings reveal compelling evidence suggesting a lack of substructures in young Class 0 and early Class I disks. Intriguingly, disk substructures begin to emerge only in sources with a bolometric temperature exceeding 160 K, indicating the rapid evolution of disk substructures during the Class I phase. Our CAMPOS survey has for the first time discovered how early disk substructures form and, as a corollary, when giant planet formation begins.
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| Wednesday, September 20, 2023 |
12:00pm |
James Windsor, Northern Arizona University |
Patchy Clouds in 1D Radiative Convective Climate Models
Abstract
Clouds are ubiquitous: they arise for every solar system planet that possesses an atmosphere and are likely a leading mechanism for obscuring spectral features in exoplanet observations. As observational capabilities continue to improve, there is need for computationally efficient planetary climate models that appropriately handle cloudy atmospheric environments that arise on these worlds. We generate a new 1D radiative-convective terrestrial planet climate model that self-consistently handles patchy clouds through a parameterized microphysical treatment of condensation and sedimentation processes. Our model is general enough to recreate Earth's atmospheric radiative environment without overparameterization, while also maintaining a simple implementation that is applicable to a wide range of atmospheric compositions and physical planetary properties. After validating this newly developed climate model against Earth, we explore the climatic effects of clouds on the inner edge of the Habitable Zone.
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| Wednesday, September 27, 2023 |
12:00pm |
Ronan Kerr, The University of Texas at Austin |
Title: TBA
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| Wednesday, October 04, 2023 |
12:00pm |
Two Talks |
Nina Filippova, The University of Texas at Austin
Title: TBA
Mabel Stephenson, The University of Texas at Austin
Title: TBA
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| Wednesday, October 11, 2023 |
12:00pm |
Dan Mayes, The University of Texas at Austin |
Title: TBA
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| Wednesday, October 18, 2023 |
12:00pm |
Two Talks |
Madeleine McKenzie, The Australian National University
Title: TBA
Lili Alderson, University of Bristol
Title: TBA
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| Wednesday, October 25, 2023 |
12:00pm |
Stephanie Douglas, Lafayette College |
Title: TBA
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