List of Past Planetary Astronomy Lunches (PALS) : 01-Jan-2016 to 01-Jun-2016


Date:   Thursday 11-Feb-2016
Speaker:   Dr. Paola Caselli, Director, Max-Planck Institute for Extraterrestrial Physics
Title:  "Chemistry at the dawn of star formation and links to our Solar System"

Before the formation of Sun-like stars, molecular clouds in our Galaxy fragment and produce dense regions called pre-stellar cores. These objects represent the initial conditions in the process of star and planet formation. They are cold (kinetic temperature < 10 K), dense (number density of H2 molecules > 10^5cm^-3, at least ten times higher than the surrounding parent cloud), and quiescent (line broadening is dominated by thermal motions). Dust grains are covered with thick icy mantles and the first steps toward Deuterium and 15N enrichments, also measured in comets, meteorites and on Earth, proceed at these early stages. Here, I shall discuss our understanding of the chemical structure of pre-stellar and protostellar cores, as well as recent theoretical predictions about protoplanetary disks in their earliest phases of evolution. Links to our own Solar System will be made.

For further information contact PALS coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 29-Feb-2016
Speaker:   Dr. Geronimo Villanueva, NASA Goddard Space Flight Center
Title:  "Redefining Mars Past and Current Habitability"

If Mars had a rich chemical past, how much of these volatiles were lost to space? Are sub-surface habitable niches connecting now with the atmosphere? The answers to these fundamental questions of Mars evolution and habitability lie in isotopic ratios and in the organic inventory. In this talk, I will present our latest maps of water and organics on Mars.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 07-Mar-2016
Speaker:   Amy Steele, University of Maryland
Title:  "Resolved Millimeter-Wavelength Observations of Debris Disks around Solar-Type Stars"

Debris disks are scaled up versions of the dust in the Solar System. The disk is revealed in the spectral energy distribution of the host star by the presence of excess flux at long wavelengths. Spatially resolved observations disambiguate the dust temperature and location, and can potentially reveal structures caused by dynamical processes involving planetesimals. Millimeter-wavelength observations probe large grains that are impervious to radiation pressure and are instead sensitive to gravitational forces due to planetesimals. Thus, these observations can provide dynamical information. In this talk, I will present results on a sample of debris disks around solar-type stars observed at millimeter-wavelengths and analyzed with MCMC modeling.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 14-Mar-2016
Speaker:   No Pals/Spring Break
Title:  

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 21-Mar-2016
Speaker:   No Pals/LPSC
Title:  

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 28-Mar-2016
Speaker:   Dr. Perry A. Gerakines, NASA Goddard Space Flight Center
Title:  "The Infrared Optical Properties of Molecules Relevant to Ices in Astrophysical Environments - Laboratory Measurements of CH4 and CO2"

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 11-Apr-2016
Speaker:   Dr. Daniel Angerhausen, NASA Goddard Space Flight Center
Title:  "Sniffing Alien Atmospheres: Exoplanet spectrophotometry (from ground-, airborne- and space-based observatories)"

In my presentation I will give a short introduction to the science of extrasolar planets, in particular the technique of transit, eclipse and phase-curve (spectro-)photometry. I will describe my various projects in this emerging field using state of the art spectroscopic and photometric instruments on the largest ground based telescopes, the 'flying telescope' SOFIA (Stratospheric Observatory for Infrared Astronomy) and the Kepler and Hubble space telescopes.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 18-Apr-2016
Speaker:   Joseph E. Rodriguez Jr., Vanderbilt University
Title:  "Transiting Planets and Eclipsing Disks From Small Telescopes"

With the success of the Kepler mission, the exoplanet field has shifted from pure discovery to a combination of discovery, demographic analysis, and detailed characterization, especially for exoplanet atmospheres. Unfortunately, a large portion of the discovered extra-solar planets are too faint to permit atmospheric characterization. The Kilodegree Extremely Little Telescope (KELT) project is a photometric survey for transiting planets around bright stars (8 < V < 11), and has discovered 17 planets transiting stars brighter than V ~11 to date. I will present a few recently discovered planets from the KELT-South survey and discuss their potential for atmospheric characterization. In addition to exoplanet science, KELT provides photometric monitoring of ~3 million stars, presenting the opportunity to perform multi-year studies of stellar variability. Using time-series photometry from KELT we are conducting the Disk Eclipse Search with KELT (DESK) survey to look for disk eclipsing events, specifically in young stellar associations. To date, the survey has discovered and analyzed four previously unknown large dimming events around the stars RW Aurigae, V409 Tau, AA Tau, and TYC 2505-672-1, the latter now representing the longest-period eclipsing object known (period ~ 69 years). I will describe our results and discuss how we are planning to search for these kinds of objects in future surveys such as LSST.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 25-Apr-2016
Speaker:   Dr. Matthew Knight/University of Maryland
Title:  "Insights from 20 Years of SOHO Comets"

Solar and Heliospheric Observatory (SOHO) recently completed its 20th year of observing. During that time it has become the most prolific comet hunting platform of all time, with more than 3000 comets discovered in its images. SOHO has revealed that the inner solar system is far more populous that previously believed, with a steady stream of small comets reaching perihelion at “sungrazing” and “sunskirting” distances every few days. The majority of these comets are dynamically related to each other as members of the well known Kreutz group, but many belong to previously unknown groups, and some may even be asteroidal in origin. In addition, SOHO has occasionally obtained spectacular observations of bright comets that passed close to the Sun, such as C/2012 S1 ISON. I will review SOHO’s various comet observations and discuss how they aid our understanding of solar system evolution, act as probes of the solar environment, reveal unique information about properties of dust, and may even yield insight into exo-planetary systems.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 02-May-2016
Speaker:   Dr. Caroline Freissinet/NASA-Goddard Space Flight Center
Title:  "Detection and preservation of chlorinated and non-chlorinated organic compounds on Mars - Results from the Sample Analysis at Mars (SAM) instrument onboard Curiosity rover."

One of the biggest concerns for the in situ detection of organics on extraterrestrial environment is the preservation potential of the molecules at the surface and subsurface given the harsh radiation conditions and oxidants they are exposed to. The Mars Science Laboratory (MSL) search for hydrocarbons is designed to understand taphonomic windows of organic preservation in the Mars’ near-surface. The Sample Analysis at Mars (SAM) instrument on the MSL Curiosity rover discovered several chlorohydrocarbon indigenous to a mudstone drilled sample, Cumberland (CB). An additional experiment, involving a chemical derivatizating reagent, allowed the detection of higher molecular mass molecules, unfortunately too hard to unambiguously identify yet. Later on, additional organic molecules were discovered in the high temperature release of the CB sample, containing the sulphur element and no chlorine, indicating that in contrast to the chlorohydrocarbons, these S-containing organics are not reaction products from the combustion of oxychlorine species. The discovery of organic matter in the martian surface means that reduced material with covalent bonds has survived despite the severe degrading conditions. The presence of organic molecules opens up habitability to another level, where the building blocks of life were available for more complex system to evolve.

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


Date:   Monday 09-May-2016
Speaker:   Dr. Xiaoduan Zou and Yun Zhang/University of Maryland
Title:  "Exploring the Moon, Asteroid and Beyond—Introduction of the Chinese Approaches" by Dr. Xiaoduan Zou and "Structural stability of rapidly rotating asteroid 65803 Didymos: A granular mechanics perspective" by Yun Zhang

"Exploring the Moon, Asteroid and Beyond—Introduction of the Chinese Approaches" by Dr. Xiaoduan Zou Abstract: This presentation will introduce China’s planetary exploration programs. The Chinese lunar spacecrafts was named as Chang’E (CE). CE 1 and CE 2 was designed as lunar satellites. CE 2 did a flyby of asteroid 4179 Toutatis after its lunar mission. CE 3 was the first lander/rover mission, and its rover Yutu explored the lunar surface. In 2017, CE 5 will return samples from the Moon. Then CE 4 will land on the far side of the Moon. After that, the Mars mission is on the way. I will outline the lunar and future missions, explain the science objects and provide a brief summary of the science results.

"Structural stability of rapidly rotating asteroid 65803 Didymos: A granular mechanics perspective" by Yun Zhang Abstract: A significant number of binary asteroid systems are observed to have primaries with spin rate very close to the critical state at which equatorial material would become gravitationally unbound. In addition, the shapes of these primaries are almost spheroidal and appear to have an equatorial ridge. An explanation for these remarkable characteristics is provided by the theory of YORP-induced rotational disruption of rubble-pile asteroids. Driven by the YORP thermal effect, asteroids with the structure of strengthless self-gravitational aggregates would be rotationally accelerated to their critical spin limits and shed mass to form secondaries by gravitational re-accumulation in orbit around the primaries. In this talk, I will introduce the proposed Asteroid Impact & Deflection Assessment (AIDA) mission and discuss the structural stability of the primary of the target of this mission, i.e., the near-Earth binary asteroid 65803 Didymos 1996 GT. Assuming the primary has a cohesionless self-gravitational rubble-pile structure, the effect of internal configuration, bulk density, and material parameters on the structural stability are investigated using the soft-sphere discrete element method (SSDEM).

For further information contact Pals coordinator Dr. Silvia Protopapa at protopapa@astro.umd.edu or (301)-405-2579.


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