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Next #SETITalks: Origins of Structure in Planetary Systems

Speaker: Ruth Murray-Clay, UC Santa Cruz

Observations confirm that planet formation is a ubiquitous process that produces a diversity of planetary systems. However, a class of solar system analogs has yet to be identified among the thousands of currently known planets and candidates, the overwhelming majority of which are more easily detectable than direct counterparts of the Sun's worlds. To understand whether our solar system’s history was unusual and, more generally, to properly characterize the galactic population of extrasolar planets, we must identify how differences in formation environment translate into different planetary system architectures. In this talk, Dr. Murray-Clay will consider our solar system in the context of theoretical advances in planet formation driven by the study of extrasolar planets. Along the way, she will discuss several examples of physical processes operating at different stages of planet formation that imprint observable structures on the dynamical and compositional demographics of planetary systems.

Free tix: http://buff.ly/2kPq0wr

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Fresh #SETITalks: Constraining the Evolution of a Delta Deposit on Mars from Orbit - Tim Goudge

Decades of planetary exploration have revealed widespread evidence for ancient fluvial activity on the surface of Mars, including deeply incised valleys, paleolake basins, and an extensive sedimentary rock record. Acquisition of high-resolution remote sensing data of the martian surface (e.g., images and topography) over the past 5-10 years have allowed for quantitative analysis of the large-scale sedimentary structures of martian sedimentary deposits.

In this talk, Dr. Goudge will focus on a detailed study of the stratigraphic architecture and channel deposit geometries of the Jezero crater delta deposit on Mars. Results from this study are used to reconstruct a scenario for the evolution of the Jezero crater delta and paleolake in which it formed. This delta deposit is a representative example of fluvial stratigraphy on early Mars, and these results can help to improve our understanding of ancient martian fluvial activity.

Watch here: http://buff.ly/2lfNMU2

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Next #SETITalks: Constraining the Evolution of a Delta Deposit on Mars from Orbit

Speaker: Tim Goudge, Jackson School of Geosciences, UT Austin

Decades of planetary exploration have revealed widespread evidence for ancient fluvial activity on the surface of Mars, including deeply incised valleys, paleolake basins, and an extensive sedimentary rock record. Acquisition of high-resolution remote sensing data of the martian surface (e.g., images and topography) over the past 5-10 years have allowed for quantitative analysis of the large-scale sedimentary structures of martian sedimentary deposits.

In this talk, Dr. Goudge will focus on a detailed study of the stratigraphic architecture and channel deposit geometries of the Jezero crater delta deposit on Mars. Results from this study are used to reconstruct a scenario for the evolution of the Jezero crater delta and paleolake in which it formed. This delta deposit is a representative example of fluvial stratigraphy on early Mars, and these results can help to improve our understanding of ancient martian fluvial activity.

Free tickets: http://buff.ly/2kBmy9y

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Fresh #SETITalks: Stellar occultations of planetary rings: from Palomar to Cassini - Phil Nicholson

Chance observations of stars as they pass behind planets have provided some of our most valuable data on the structure of planetary ring systems, beginning with the discovery of the uranian rings with the Kuiper Airborne Observatory in 1977. As a graduate student at Caltech in the 70s, I became involved first in studies of the dynamically-curious uranian rings at Mount Palomar and later in unraveling the story of the even more baffling ring arcs of Neptune. I will review some of the highlights of this early work, which led to my current involvement in the Cassini mission at Saturn, observing stellar occultations with the VIMS (Visual and Infrared Mapping Spectrometer) instrument. Over 150 such occultations have been observed over the past 12 years, leading to the discovery and/or characterization of such novel features as self-gravity wakes, numerous density and bending waves, eccentric and inclined ringlets, `normal modes’ on gap edges and instances of `viscous overstability’ in denser regions of the rings. Our ring observations have also provided insights into the internal structure of Saturn itself.

Watch here: http://buff.ly/2lB7hpQ

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Next #SETITalks - Stellar occultations of planetary rings: from Palomar to Cassini

Speaker: Phil Nicholson, Cornell University

Chance observations of stars as they pass behind planets have provided some of our most valuable data on the structure of planetary ring systems, beginning with the discovery of the uranian rings with the Kuiper Airborne Observatory in 1977. As a graduate student at Caltech in the 70s, I became involved first in studies of the dynamically-curious uranian rings at Mount Palomar and later in unraveling the story of the even more baffling ring arcs of Neptune. I will review some of the highlights of this early work, which led to my current involvement in the Cassini mission at Saturn, observing stellar occultations with the VIMS (Visual and Infrared Mapping Spectrometer) instrument. Over 150 such occultations have been observed over the past 12 years, leading to the discovery and/or characterization of such novel features as self-gravity wakes, numerous density and bending waves, eccentric and inclined ringlets, `normal modes’ on gap edges and instances of `viscous overstability’ in denser regions of the rings. Our ring observations have also provided insights into the internal structure of Saturn itself.

Free tickets: http://buff.ly/2jS9YpY

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Fresh #SETITalks: How Stars Form - Christopher McKee, UC Berkeley

Stars are the atoms of the universe. The process by which stars form is at the nexus of astrophysics since they are believed to be responsible for the re-ionization of the universe, they created the heavy elements, they play a central role in the formation and evolution of galaxies, and their formation naturally leads to the formation of planets. Whereas early work on star formation was based on the assumption that it is a quiescent process, it is now believed that turbulence plays a dominant role. In this overview, I shall discuss the evolution of our understanding of how stars form and current ideas about the stellar initial mass function, the rate of star formation, the formation of massive stars, the role of magnetic fields, and the formation of the first stars.

Watch here: http://buff.ly/2k63YGc

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Next #SETITalks: How Stars Form

Speaker: Christopher McKee, UC Berkeley

Stars are the atoms of the universe. The process by which stars form is at the nexus of astrophysics since they are believed to be responsible for the re-ionization of the universe, they created the heavy elements, they play a central role in the formation and evolution of galaxies, and their formation naturally leads to the formation of planets. Whereas early work on star formation was based on the assumption that it is a quiescent process, it is now believed that turbulence plays a dominant role. In this overview, I shall discuss the evolution of our understanding of how stars form and current ideas about the stellar initial mass function, the rate of star formation, the formation of massive stars, the role of magnetic fields, and the formation of the first stars.

More info and free tickets: http://buff.ly/2ju7kS8

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Fresh #SETITalks - Exocomets: Now you see them, now you don't - Barry Welsh, UC Berkeley

Present technology does not enable us to view images of these kilometer-sized infalling bodies, but the evaporation of gaseous products liberated from exocomets that occurs close to a star can potentially cause small disruptions in the ambient circumstellar disk plasma. For circumstellar disks that are viewed “edge-on” this evaporating material may be directly observed through transient (night-to-night and hour-to-hour) gas absorption features seen at rapidly changing velocities. Using high resolution spectrographs mounted to large aperture ground-based telescopes, we have discovered 15 young stars that harbor swarms of exocomets. In this lecture we briefly describe the physical attributes of comets in our own solar system and the instrumental observing techniques to detect the presence of evaporating exocomets present around stars with ages in the 10 – 100 Myr range. We note that this work has particular relevance to the dramatic fluctuations in the flux recorded towards “Tabby’s star” by the NASA Kepler Mission, that may be explained through the piling up of swarms of exocomets in front of the central star.

Watch here: http://buff.ly/2kEJDrw

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Fresh #SETITalks: The Late Veneer and Earth's habitability - Norm Sleep

Asteroid impacts were a hazard to any life on the Hadean Earth. A traditional approach to geochemical models of the asteroid impactors uses the concentration of highly siderophile elements including the Pt-group in the silicate Earth. These elements occur in roughly chondritic relative ratios, but with absolute concentrations less than 1% chondrite. This veneer component implies addition of chondrite-like material with 0.3-0.7% mass of the Earth’s mantle or an equivalent planet-wide thickness of 5-20 km. The veneer thickness, 200-300 m, within the lunar crust and mantle is much less. The accretion of a large number of small bodies would provide comparable thicknesses to both bodies, as the effect of gravity is modest.

Watch here: http://buff.ly/2j5NSQz

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TODAY #SETITalks - Exocomets: Now you see them, now you don't

Speaker: Barry Welsh, UC Berkeley

Minor bodies such as Kuiper Belt objects, comets, and asteroids constitute the rocky and icy debris left over from the planet building phase of our solar system. The existence of reservoirs of small rocky bodies (i.e., asteroids/planetesimals) in orbits around young stellar systems is now well established, with their presence being required by current (exo)planetary formation theories. The initial proto-planetary disks that contain the reservoir of dust and gas required to form (exo)planets are short lived (<< 1 Myr) and thus the circumstellar debris disks observed around young stars of ages 10 – 50 Myr must be being continually replenished by collision and evaporation events amongst planetesimals. In such systems, the gravitation field associated with the newly formed exoplanets can potentially enable the disruption of large numbers of these kilometer-sized icy bodies into trajectories directed towards the young central star.

Present technology does not enable us to view images of these kilometer-sized infalling bodies, but the evaporation of gaseous products liberated from exocomets that occurs close to a star can potentially cause small disruptions in the ambient circumstellar disk plasma. For circumstellar disks that are viewed “edge-on” this evaporating material may be directly observed through transient (night-to-night and hour-to-hour) gas absorption features seen at rapidly changing velocities. Using high resolution spectrographs mounted to large aperture ground-based telescopes, we have discovered 15 young stars that harbor swarms of exocomets. In this lecture we briefly describe the physical attributes of comets in our own solar system and the instrumental observing techniques to detect the presence of evaporating exocomets present around stars with ages in the 10 – 100 Myr range. We note that this work has particular relevance to the dramatic fluctuations in the flux recorded towards “Tabby’s star” by the NASA Kepler Mission, that may be explained through the piling up of swarms of exocomets in front of the central star.

Free tickets: http://buff.ly/2jS3oit
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