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iPlex Lunch - winter-2019

Stellar Activity from Spot Transit Mapping

Jan. 11, 2019
noon - 1 p.m.
Geology 3814

Presented By:

  • Adriana Valio - CRAAM - Mackenzie University, Brazil)
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Stellar activity manifests itself in the form of spots and faculae on the star surface and also as flares and mass ejections. When an orbiting planet transits the star and occults one of these features, small signatures are imprinted in the transit light curve. These can be modeled to yield the physical characteristics of spots and faculae, stellar rotation and differential rotation, and even magnetic cycles given long enough time series. Flares have also been detected from active stars. The impact of these on possible living organisms in close orbits planets will be discussed.

Riding Centaurs Along Their Orbits

Jan. 28, 2019
noon - 1 p.m.
Slichter 3853

Presented By:

  • Estela Valenzuela - University of Central Florida
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Centaurs are objects that provide the possibility of studying the smaller trans-Neptunian objects at much closer distances. Understanding their long-term photometric behavior is particularly useful for the study of physical properties such as shape, density or even to describe properties such as rings or comae. I will explain how to extract these properties using photometric data.

The Role of Tidal Dissipation in the Evolution of Planetary Satellites

Feb. 1, 2019
noon - 1 p.m.
Slichter 3853

Presented By:

  • Tushar Mittal - UC Berkeley
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Tidal dissipation plays a critical role in controlling both the orbital evolution and the internal structure of planetary satellites. In this talk, I will discuss a couple of case studies illustrating these processes: 1) the Phobos-Mars system for the orbital migration of satellites and their potential breakup and 2) Enceladus as a planetary body whose internal structure is controlled by exactly where tidal dissipation occurs. Finally, I will touch upon the implications of these processes for the habitability of each satellite, as well as potentially the host planets.

Atmospheric Retrieval of Exoplanets

Feb. 25, 2019
1 p.m. - 2 p.m.
Slichter 3853

Presented By:

  • Kevin Heng - University of Bern
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I will review the method of exoplanet atmospheric retrieval, focusing on transmission spectra. I will discuss in great detail a key practical limitation known as the normalisation degeneracy, examining it in three different regimes of atmospheric retrieval (HST, JWST, ground-based high-resolution). Finally, I will review an analysis of all 38 existing Hubble Space Telescope-WFC3 near-infrared transmission spectra to a Bayesian hierarchy of retrievals.