Theoretical Astronomy

Don't Rain on my Planet: The Importance of Clouds and Hazes for Understanding Exoplanets and Brown Dwarfs

Clouds and hazes shape the observed spectra of exoplanets and brown dwarfs. Yet we know from Earth that clouds and hazes are inherently difficult to model and are the leading source of uncertainty in terrestrial GCM forecasts of globals warming. Dr. Marley will review what we know about the chemistry and physics of clouds in substellar atmospheres and discuss some pathways to haze formation in exoplanet atmospheres.

Building a habitable planet: the physics and chemistry of planet formation

 Habitable planets must not only reside in a narrow range of distances from their stars, but they also must contain water and carbon. This is easier said than done. In this talk, IDr. Kress will discuss the chemistry in protoplanetary disks, and the physical processes by which earth-like planets form. In particular, Dr. Kress will focus on how habitable planets obtain carbon and water, the key ingredients for life. 

Observing String Multiverse with Astrophysical Black Holes

One of the most intriguing and controversial recent ideas in cosmology and string theory is that the Universe is highly inhomogeneous on the length scales much longer than its currently observable part, with many of the fundamental "constants" of Nature varying on the ultra-long length scales. Our location in this cosmic landscape is to a large extent determined by requiring that the local particle physics parameters should allow for life to develop. Dr.

Water, Molecular Oxygen and Ice in Star-Forming Molecular Clouds

The Oxygen is the third most abundant element in the universe and its molecules (oxygen, water, carbon dioxide) a basic ingredient of life on Earth. Oxygen chemistry in the interstellar molecular clouds which form stars and planets has long been a mystery. We discuss that mystery and propose its resolution in this talk. Its resolution also suggests a way to synthesize complex carbon molecules in interstellar clouds and in protoplanetary disks.

Connecting Galaxies, Halos, and Star Formation Rates across Cosmic Time

Numerous complementary observations over the past decade have pinned down the initial conditions for structure formation just a few hundred thousand years after the big bang, and also indicate that the matter density of the Universe is dominated by "cold" dark matter (CDM). The non-linear evolution of structures can then be followed using numerical simulations of the dark matter distribution, which indicate that dark matter quickly clumps into bound objects known as dark matter halos.

First Things in the Universe

The first structure to form in the Universe can now be predicted from ab initio simulations starting with the known initial conditions of our Universe. What is found is a rich history with massive stars, black holes, UV radiation, and hydrogen molecules among others playing significant roles. Using supercomputer simulations allows us to visually show the origin of the first stars, their demise and impact on their future, which is our past, in the Universe' first billion years. 

The Hunt for Hidden Dimensions

 Extra dimensions of space may be present in our universe. Their discovery would dramatically change our view of the cosmos and would prompt many questions. How do they hide? What is their shape? How many are there? How big are they? Do particles and forces feel their presence? This lecture will explain the concept of dimensions and show that current theoretical models predict the existence of extra spatial dimensions which could be in the discovery reach of present and near-term experiments.

Giant Planet Formation

The observed properties of giant planets, models of their evolution, and observations of protoplanetary disks all provide constraints on the formation of gas giant planets.  The four largest planets in our Solar System contain considerable quantities of hydrogen and helium, which could not have condensed into solid planetesimals within the protoplanetary disk.  The preponderance of evidence supports the core nucleated gas accretion model of formation of the giant planets.

Black Holes: End of Time or a New Beginning?

Black holes are popularly associated with death and destruction (excluding romances dealing with the redemptive properties of wormholes). However, their conventional astrophysical role is now seen as regenerative and they play a major role in the formation and evolution of galaxies stars and, arguably, organic molecules. Some possible ways in which they may impact the research of the SETI Institute will be discussed and ways in which they may have played a role in the history of our solar system will be briefly discussed. 

Terrestrial Planet Formation and Habitability in Binary Star Systems

Most stars reside in binary/multiple star systems. Perturbations from a companion star can disrupt the formation and long-term stability of planets. More than 40 extrasolar planets have been detected in binary star systems, including 3 with stellar separations of only ~20 AU, well within the region spanned by planets in our Solar System. I will present results from a large suite of numerical simulations that explore the final stages of terrestrial planet formation in main sequence binary star systems.


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