Ultraviolet Observations of Galaxies
Mark Rutkowski, Minnesota State Univeristy
Ultraviolet observations are essential for answering fundamental questions regarding the role and impact of galaxies in universe. I’ll discuss a number of past, ongoing, and future UV-optical-near IR high redshift surveys with which I am involved and the specific constraints the UV provides on these open questions. Specifically, I’ll highlight the utility of UV observations of starbursts and quiescent galaxies alike for constraining the history of reionization, hierarchical assembly, and (if there’s time) the cosmic history of metals.
Dr. Janna Levin
Our Future in Space: The Moon and Beyond
Jack Burns, University of Colorado Boulder
Why do we explore space? How do we explore
space? Where should we explore? What are
the tools for space exploration? These questions will be addressed in this talk focused on
the future of human and robotic exploration of
the solar system and beyond. Since the end of
the Apollo program, the justification for the human space program has proven elusive. We will
borrow a page from the computer and new
commercial space companies to argue for an
inspirational approach to the next phase of
exploration beyond Earth orbit. The “how” is
addressed with NASA’s new Orion and Space
Launch Systems along with new launch systems being developed by private companies
such as SpaceX and Blue Origin. We will argue
that both the Moon and Mars can be explored
through a combination of governmental programs, international partnerships, and public-
private partnerships. The tools for exploration
include telerobotics where astronauts aboard
NASA’s Lunar Gateway in orbit of the Moon
will operate rovers and deploy telescopes on
the lunar surface in a new synergy between
robots and humans.
A Masing BAaDE’s Window
Ylva Pihlström, University of New Mexico
Evolved, intermediate mass stars are tracers of an intermediate age stellar population. Due to high mass-loss rates, they harbor circumstellar envelopes, in which different types of molecular maser emission can be observed. The maser emission allows not only studies of the physical conditions in the circumstellar envelope itself, but also can be used to test Galactic dynamics. Both these facets are investigated in the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey, using 28,000 SiO maser emitting stars in the Milky Way galaxy observed by the VLA and ALMA. I will give an overview of this survey and discuss a few of our results and challenges: A marginal flux bias exists in our sample due to two different sets of frequencies observed, which could partly be corrected for using longer integration times at ALMA. We have collected an extensive infrared data set for our sample, providing a means of modeling parameters such as bolometric luminosities and mass loss rates. Infrared colors further helps to separate C-rich from O-rich stars, and may also be tied to line ratios, tying back to the conditions in the circumstellar envelope.
Searching for diffuse radio emission in merging galaxy clusters with LOFAR
Amanda Wilber, Universität Hamburg
Galaxy cluster mergers are powerful drivers of turbulence and shocks, which can accelerate cosmic-ray electrons within the magnetic field of the intracluster medium (ICM) to generate Megaparsec-sized radio structures. Actively merging clusters are excellent astrophysical laboratories for studying the nature of magnetic fields and the physics of particle acceleration. Questions still remain in identifying the source of cosmic-ray electrons that appear to fill the ICM so uniformly, and in determining the origin and amplification mechanisms of cluster magnetic fields. With its high-resolution, extended coverage, and sensitivity to radio emission with low surface brightness, the LOw Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) gives us an unparalleled opportunity to hunt for diffuse radio sources in distant galaxy clusters. In this talk I present the results of LoTSS observations which reveal never-before-seen diffuse radio emission in the merging galaxy clusters Abell 1132 and Abell 1314.
The Role of Ecology in Star and Planet Formation
Megan Reiter, Royal Observatory Edinburgh
Understanding how feedback regulates star and planet formation is one of the outstanding unsolved problems in astrophysics. Stellar feedback affects all astrophysical scales: it shapes the interstellar medium and mass function of galaxies, determines the fragmentation and star formation efficiency of molecular clouds, and plays a central role in the geochemical evolution of terrestrial planets. High-mass stars shape the local star-forming environment – the ecology – via radiation pressure, stellar winds, photoionization, and supernovae. Photoionization is the least explored of these; however, recent numerical work suggests that it dominates the destruction of molecular clouds and planet-forming disks around stars born in clusters. These predictions depend critically on the dynamics of newborn stars and feedback-altered gas, but these quantities are poorly unconstrained. I will talk about two on-going surveys using ALMA, MUE/VLT, and M2FS/Magellan to measure gas and stellar kinematics in order to test the role of environment in shaping the outcome of star and planet formation.
Charting the Outer Reaches of Exoplanetary Systems: Wide-Separation Giant Planet Demographics with Direct Imaging
Eric Nielsen, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University
Over the past decade, the combination of advances in adaptive optics, coronagraphy, and data processing has enabled the direct detection and characterization of giant exoplanets orbiting young, nearby stars. In addition to the wealth of information about exoplanetary atmospheres we obtain from spectroscopy of directly imaged planets, the demographics of these wide-separation planets allow us to directly test theories of planet formation, probing the outer planetary systems compared to transit and radial velocity techniques. In this talk I will present results from the Gemini Planet Imager Exoplanet Survey (GPIES), which surveyed 521 nearby stars for giant planet and brown dwarf companions orbiting beyond 5 AU, and is one of the largest, deepest direct imaging searches for exoplanets every conducted. The overall occurrence rate of substellar companions, and trends with companion mass, semi-major axis, and stellar mass are consistent with giant planets forming via core accretion, and point to different formation mechanisms for giant planets and brown dwarfs between 10 and 100 AU.
Simulating Planetesimal Formation in the Kuiper Belt and Beyond
Rixin Li, University of Arizona
A critical step in planet formation is to build super-km-sized planetesimals in protoplanetary disks. The origin and demographics of planetesimals are crucial to understanding the Solar System, circumstellar disks, and exoplanets. I will overview the current status of planetesimal formation theory. Specifically, I will present our recent simulations of planetesimal formation by the streaming instability, a mechanism to aerodynamically concentrate pebbles in protoplanetary disks. I will then discuss the connections between our numerical models and recent astronomical observations and Solar System explorations. I will explain why all planetesimals likely formed as binaries.