Pizza Lunch: Ethan Dederick
Sep 28 @ 12:30 pm – 1:30 pm
Pizza Lunch: Ethan Dederick

Mars One: Current State & Future Plans

Colloquium: Ben Weiner
Oct 9 @ 3:15 pm – 4:15 pm
Colloquium:  Ben Weiner @ BX102

Searching for Dwarf Satellites around Milky Way – Analog Galaxies with the SAGA survey

Ben Weiner, Steward Observatory

Dwarf satellites of massive galaxies are a probe of many issues in galaxy evolution and cosmology, including the nature of low-mass galaxies, star formation at early times, accretion into halos, and the abundance of low-mass dark matter halos. Much attention has been devoted to the number and nature of Milky Way and M31 dwarf satellites, especially the “missing satellites problem.” However, we know very little about dwarf satellites outside the Local Group below the mass of the LMC, and we don’t know if the MW and M31 satellite systems are typical. The SAGA (Satellites Around Galactic Analogs) survey collaboration aims to address this with both observational and theoretical studies of satellite abundances and properties around Milky Way analog central galaxies. I will present results from our MMT/Hectospec wide field spectroscopic surveys for satellites. We have surveyed the fields of several nearby galaxies that are similar to the Milky Way to detect and spectroscopically confirm dwarf satellites.  We find a range of numbers of satellites, suggesting that there is a significant variance in halo histories.  We also find that not all dwarf systems resemble the Milky Way and M31 systems. I will discuss these results and some of the implications on the life cycle of satellites that we can infer from satellite abundances and properties, including their images and spectra.


Colloquium: Rich Zurek (Host: Jim Murphy)
Jan 22 @ 3:15 pm – 4:15 pm
Colloquium:  Rich Zurek        (Host: Jim Murphy) @ BX102

Evolving Perspectives on the Atmosphere and Climate of Mars

            Dr. Richard Zurek, JPL

            Abstract: The planet Mars has both fascinated and tantalized humankind since the invention of the telescope and now well into the age of exploration from space. The first of three waves of space missions to Mars were flyby spacecraft that returned images of a heavily cratered planet with a thin atmosphere, suggesting Mars was more like the Moon than an older Earth. However, Mariner 9, the first spacecraft to orbit another planet, found vast channel and valley networks carved into its surface, as well as towering volcanoes, suggesting that ancient Mars was once much more Earth-like. Subsequent missions have landed on the planet and new orbiters have probed the planet at ever increasing spatial resolution and spectral coverage. As a result of the latest round of space exploration, Mars is revealed to be a complex, diverse planet— one whose climate has changed dramatically over time from an ancient atmosphere where water was active on its surface to a drier, thinner atmosphere shaped by periodic ice ages, to the present atmosphere where dynamic change continues today.

Dr. Zurek is the Chief Scientist in the Mars Program Office, Project Scientist, MRO.

Colloquium Thesis Proposal: Kathryn Steakley (Host: Jim Murphy)
Jan 29 @ 3:00 pm – 4:00 pm
Colloquium Thesis Proposal:  Kathryn Steakley  (Host: Jim Murphy) @ BX102

Exploring Impact Heating of the Early Martian Climate

Kathryn Steakley, NMSU

ABSTRACT: Geological evidence implies that Mars may have had a more warm and wet environment during the late Noachian / early Hesperian era (3.5–3.8 billion years ago), but climate models struggle to reproduce such warm conditions. Prior studies with one-dimensional atmospheric models indicate that the water and energy from impacts could provide enough greenhouse warming to raise temperatures above the freezing point of liquid water for many years. We will use the NASA Ames Research Center Mars GCM to characterize potential atmospheric changes induced by impactors ranging in diameter from 50 m to 100 km on a range of early Mars surface pressure scenarios (10-mbar, 100-mbar, 300-mbar, 1-bar, 2-bar, 3-bar). Our objectives are 1) to examine the temperature behavior of the early Martian climate following impacts and determine if environmental conditions on its surface could support liquid water for extended periods of time, and 2) to quantify precipitation rates and examine rainfall patterns on a simulated early Martian surface following impacts and determine if this mechanism is possibly responsible for the formation of observed river valley networks on Mars. Examining climate conditions after impacts with a GCM will allow us to test a potential mechanism for heating the early Martian atmosphere, constrain the magnitude and temporal duration of these potential heating events, and provide insight regarding the availability of liquid water on early Mars which is relevant to its past habitability.


Colloquium: Mark Wardle
Oct 28 @ 3:15 pm – 4:15 pm
Colloquium: Mark Wardle @ Biology Annex 102

Star formation in the vicinity of the supermassive black hole at the Galactic Centre

Dr. Mark Wardle, Macquarie University

The disruptive tidal field near supermassive black holes overcomes the self-gravity of objects that are less dense than the Roche density.  This was once expected to suppress star formation within several parsecs of  Sgr A*, the four million solar mass black hole at the centre of the Galaxy.   It has since become apparent that things are not this simple:  Sgr A* is surrounded by a sub-parsec-scale orbiting disk of massive stars, indicating a star formation event occurred a few million years ago.    And on parsec scales,  star formation seems to be happening now:  there are proplyd candidates and protostellar outflow candidates,  as well as methanol and water masers that in the galactic disk would be regarded as sure-fire signatures of star formation.  In this talk, I shall consider how star formation can occur so close to Sgr A*.

The stellar disk may be created through the partial capture of a molecular cloud as it swept through the inner few parsecs of the galaxy and temporarily engulfed Sgr A*.  This rather naturally creates a disk of gas with the steep surface density profile of the present stellar disk.  The inner 0.04 pc  is so optically thick that it cannot fragment, instead accreting onto Sgr A* in a few million years; meanwhile the outer disk fragments and creates the observed stellar disk.   The isolated young stellar objects found at larger distances, on the other hand,  can be explained by stabilisation of clouds or cloud cores by the high external pressure that permeates the inner Galaxy.   A virial analysis shows that clouds are indeed tidally disrupted within 0.5 pc of Sgr A*, but outside this the external pressure allows self-gravitating clouds to survive, providing the raw material for ongoing star formation.


Pizza Lunch: Jean McKeever
Mar 13 @ 12:30 pm – 1:30 pm
Pizza Lunch: Jean McKeever @ AY 119

Red Giants in Eclipsing Binary Systems

Jean McKeever


Pizza Lunch: Michael Engelhardt (Physics), “The quarks in the proton go round and round …”
Apr 2 @ 12:30 pm – 1:30 pm
Pizza Lunch: Michael Engelhardt (Physics), "The quarks in the proton go round and round ..." @ AY 119

The quarks in the proton go round and round …