12:00–1:00 pm Zoom
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Ilaria Lonoce (UChicago) "The stellar initial mass function and its challenging measurement"
The stellar initial mass function (IMF) plays a fundamental role in our understanding of the processes that regulate the formation of every stellar system and its subsequent evolution. Moreover, our knowledge of stellar population properties and the star formation history in distant galaxies rely on how well we can constrain the IMF in galaxies in the nearby universe. However, the measurement of the IMF in integrated light for galaxies or distant globular clusters is really challenging due to the weakness of the spectroscopic lines, and the degeneracy between age and metallicity effects. In recent decades, thanks to the availability of higher quality data and models, the IMF has been measured for an increasing number of local ellipticals, providing evidence for non-universality among different galaxies. This intriguing finding may be signaling a correlation between the IMF and stellar and/or kinematic properties. However, before exploring this possibility, it is critical to understand if different measures of the IMF, obtained with different indicators, methods, and models, are all equally reliable, and if they lead to consistent overall results. And does the IMF show radial variations or vary with galaxy environment?
In this talk I will present our work on, and approach to, this challenging problem. We have compared different techniques for deriving the IMF and performed simulations to highlight possible biases of each analysis, exploiting a sample of ~10 local ellipticals with high S/N Magellan spectroscopic data. I will focus on new results we have obtained on the IMF for two central ellipticals of the Hydra I cluster, as well as their surrounding stellar halo.
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Madison Brady (UChicago) "Assessing /TESS/'s Yield Around Nearby M Dwarfs"
Terrestrial planets are easier to detect around M dwarfs than other types of stars, making them promising targets for next-generation atmospheric characterization studies. The /TESS /mission has greatly increased the number of known M dwarf planets that we can use to perform population studies. In this talk, I discuss simulations used to assess /TESS/'s yield and show that /TESS/ has detected fewer rocky planets around late M dwarfs than expected. This can be explained by a decrease in planetary occurrence around the smallest types of stars, which could have implications with regards to future searches for Earth-like exoplanets. I also use these simulations to estimate the number of rocky M dwarf planets that /TESS/ will observe by the end of year 4 of its mission, as well as the number of transiting planets it has missed.
