List of Past Planetary Astronomy Lunches (PALS) : 01-Sep-2013 to 31-Dec-2013


Date:   Tuesday 23-Jul-2013
Speaker:   Roberto Sanchis-Ojeda (Kavli Institute, MIT)
Title:  Kepler-78b: Transits and occultations of an Earth-sized planet in an 8.5 hour orbit

In this talk I will present the recently discovered Earth-sized planet Kepler-78b [1]. This planet was found in an ongoing effort to discover new ultra-short period planets on the Kepler data using the Fourier Transform technique. With an orbital period of 8.5 hours, the planet completed more than 3000 orbits during the 3.5 years of available data, allowing for a clear detection of the shallow transit depth (200 parts per million) and even shallower occultation depth (10 parts per million). We interpret the observed secondary eclipse as a combination of reflected light and thermal emission from the surface of the planet. With a Kepler magnitude of 11.5, a follow-up radial velocity campaign is possible and should be rewarding, potentially making Kepler-78b the first Earth-sized exoplanet with a measured mass. In this talk I will also present some new preliminary results that show that planets with orbital periods shorter than 12 hours are uncommon and tend to be smaller than twice the size of the Earth. Finally, I will also discuss how the ability of these planets to survive in such short orbital periods can only be explained if the planets have high densities, which in some cases leads to strong constraints on the composition of the planet.

[1] http://arxiv.org/abs/1305.4180

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Wednesday 24-Jul-2013
Speaker:   Adam McKay (NMSU)
Title:  Characterization of the Gas Production in Comets 103P/Hartley and C/2009 P1 Garradd

Cometary nuclei have a primitive composition that likely reflects that of the region of the solar nebula in which they formed. Therefore studies of the volatile composition of comets are important for understanding formation of volatile material in the protosolar disk and delivery of volatiles to the terrestrial planets. Since the nucleus of the comet is rarely observed directly, studies of gas production in comets are vital for characterizing their volatile composition. We present analysis of high spectral resolution optical observations of comets 103P/Hartley and C/2009 P1 Garradd obtained with the ARCES echelle spectrometer mounted on the Astrophysical Research Consortium 3.5-meter telescope at Apache Point Observatory located in Sunspot, NM. The spectra contain transitions of CN, C2, CH, NH2, and OI. We also present analysis of observations of CO, H2O, and C2H6 for Garradd obtained with the CSHELL IR spectrometer mounted on NASA's Infrared Telescope Facility. Both of these comets were well studied during their recent apparitions, from a combination of the DIXI flyby and a remote observing campaign for Hartley and extensive remote observations obtained throughout the apparition for Garradd, covering a wide range of heliocentric distance both pre- and post-perihelion. We compare our results to measurements of candidate parent species reported in the literature. We discuss what our results imply about the origin of the observed species and the chemical heterogeneity of these comets.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 24-Sep-2013
Speaker:   Himadri Das (Assam University, India)
Title:  Imaging Polarimetry of Comet C/2009 P1 (Garradd)

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 01-Oct-2013
Speaker:   Your Colleagues
Title:  DPS Practice Talks

Practice talks from your colleagues for the 45th Annual Meeting for the American Astronomical Society's Division for Planetary Sciences.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 15-Oct-2013
Speaker:   To be announced
Title:  To be announced

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 22-Oct-2013
Speaker:   [CANCELLED]
Title:  [CANCELLED]

Unfortunately, our speaker had to cancel his talk. We will try to reschedule him for a future PALS.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 29-Oct-2013
Speaker:   Doug Hamilton (UMD)
Title:  Titanic Collisions!

Titan is arguably the Solar System's most unusual satellite. It is fifty times more massive than Saturn's other moons and is the only satellite with a substantial atmosphere. Titan shares a unique resonance with nearby Hyperion, but otherwise sits in a particularly large gap between Rhea and Iapetus. Titan has the largest eccentricity of all Saturn's regular satellites and has a reasonably large orbital tilt; its distant neighbor Iapetus has an even more impressive eight degree free inclination. None of these peculiarities are even partially understood. Until now!

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 05-Nov-2013
Speaker:   Margaret McAdam, Ashlee Wilkins (UMD)
Title:  The Astronomy Gentleladies Network (AGN)

In this presentation, the Astronomy Gentleladies Network (AGN) highlights of some of the issues facing women and minorities from STEM fields. We hope to have an open discussion about our personal experiences with some common issues and discuss some of the recent research behind them. This talk aims to empower everyone to promote equality in their every day lives by suggesting a few simple ideas to combat the most common barriers to women and minorities in science.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 12-Nov-2013
Speaker:   Christopher Hamilton (GSFC)
Title:  Volcanism and interior processes on Io

Jupiter’s moon Io is the most volcanically active body in the Solar System and offers insight into processes of tidal heating, melt generation, and magma ascent. In this study, we examine the distribution of volcanoes using the first 1:15,000,000 global geologic map of Io and a variety of geospatial analysis techniques. Results show that there is a 30 to 60 degree offset between volcano clusters and the surface heat flux maxima predicted by a range of solid body tidal heating models. If the locations of volcanic activity are directly correlated with underlying melt production, this offset cannot be explained by existing models. However, recent identification of an induced electromagnetic field within Galileo magnetometer data implies that Io has a subsurface “magma ocean” (i.e., a globally continuous layer of least 20% partial melt and 50 km thickness). This raises the intriguing possibility that fluid dissipation may modify Io's tidal response and affect its locations of active volcanism.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 19-Nov-2013
Speaker:   Aki Roberge (GSFC)
Title:  Gas and Dust in Debris Disks: Clues to the Late Stages of Planet Formation

The basic character of debris disks was established soon after their discovery in the mid-1980's. These disks around nearby main sequence stars are composed of material (mostly dust) produced by collisions and/or evaporation of extrasolar asteroids and comets. However, fundamental observational questions about debris disks remain unanswered. How much material do debris disks typically contain and how does it evolve with time? What is the composition of their dust and gas? Are planets present or forming in the disks? Answers to these questions will provide insights into the late stages of planetary system formation and the origins of terrestrial planet atmospheres. In this talk, I will explain our current understanding of the place of debris disks in the planet formation process. Progress toward addressing the questions given above will be discussed, with emphasis on recent studies of the small but important gas component. Finally, I will outline the implications of debris dust for future efforts to directly image and characterize extrasolar terrestrial planets.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 26-Nov-2013
Speaker:   Scott Guzewich (GSFC)
Title:  Aerosols of the Martian Atmosphere

The three aerosols of the Martian atmosphere: dust, water ice and carbon dioxide ice, all play a major role in the current Martian climate. While their presence and climactic significance has been known for decades, new observations have shown that there is much that we still don't understand. Specifically, I will discuss the recently discovered "detached dust layers", the unexpectedly large role that tropical water ice clouds appear to play in atmospheric dynamics and the recent confirmation of carbon dioxide snow and its possible role in the Martian polar vortices.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 03-Dec-2013
Speaker:   Cancelled
Title:  Cancelled

PALS is cancelled today due to a scheduling conflict with a NASA town hall meeting.

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


Date:   Tuesday 10-Dec-2013
Speaker:   Brian Jackson (DTM)
Title:  On the Edge: Exoplanets with Orbital Periods Shorter Than a Peter Jackson Movie

The vast majority of gas giant exoplanets with close-in orbits is unstable against tidal decay and may spiral into their host stars in only a few billion years. Moreover, rocky planets with orbital periods of only a few hours would induce stellar radial velocity (RV) signals measurable by current facilities. Motivated by these considerations, I recently led a search for very short-period transiting planets using Kepler data. We found four planetary candidates, with periods as short as four hours, and one candidate was independently discovered and confirmed by follow-up RV observations. This planet, Kepler-78 b, has an Earth-like density but an orbital period of only 8.5-hours and a surface temperature approaching 3,000 K. These potentially rocky planets in orbital periods of only a few hours have opened an exciting, new avenue for exoplanet study but pose severe challenges to theories of planet formation and evolution. In this presentation, I’ll discuss our search for very short-period planets and their observational and theoretical implications. I’ll describe why the usual origin scenarios for close-in planets may not apply to these candidates and the possibility that they are remnant fossil cores of disrupted close-in gas giants. Whatever their origins, such planets would be particularly amenable to discovery by the planned TESS mission and detailed follow-up.

Brian Jackson -- Carnegie Dept. of Terrestrial Magnetism, Washington DC bjackson@dtm.ciw.edu -- http://www.astrojack.com

For further information contact PALS coordinator Dr. Michael Kelley at msk@astro.umd.edu or 301-405-3796.


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