Dr. Janna Levin
Protoplanetary disk rotation curves and the kinematic detection of protoplanets
Simon Casassus, Universidad de Chile
Direct detections of protoplanets still embedded in a gaseous protoplanetary disk have been remarkably elusive in their thermal-IR radiation. Yet most models for the structures observed in disks involve planet/disk interactions. The gas and dust density fields are thus appealing proxies to trace embedded bodies, but they are not sufficient to ascertain a planetary origin. New hopes for protoplanet detection come from the disk kinematics, which should also bear their dynamical imprint. The last couple of years have seen the first indirect detection of protoplanets, with the observation of small deviations from Keplerian rotation in molecular line channel maps, and their reproduction in hydrodynamical simulations. Can we use the gas kinematics directly to pin-point the location and measure the dynamical mass of giant planets? The theoretical velocity reversal along the wakes of a protoplanet should be observable as a Doppler-flip, provided that the background flow is adequately subtracted. This axially symmetric flow is a generalized rotation curve, including also the radial and vertical velocity components, which bear the imprint of accretion, winds, and of the theoretical meridional flows in the case of planet/disk interactions. I will present a technique to calculate disk rotation curves, with applications to ALMA long baseline data in HD100546 and in HD163296.
The Circumgalactic Medium at Cosmic Noon with KCWI
Nikole Nielsen, Swinburne University of Technology
The star formation history of the universe reveals that galaxies most actively build their stellar mass at cosmic noon (z=1-3), roughly 10 billion years ago, with a decrease toward present-day. The resulting metal-enriched material ejected from these galaxies due to supernovae and stellar feedback is deposited into the circumgalactic medium (CGM), which is a massive reservoir of diffuse, multiphase gas out to radii of 200 kpc. The CGM is the interface between the intergalactic medium and the galaxy, through which accreting filaments of near-pristine gas must pass to contribute new star formation material to the galaxy and outflowing gas is later recycled. Simulating these baryon cycle flows is crucial for accurately modeling galaxy evolution. While the CGM is well-studied at z<1, little attention has been paid to the reservoir when star formation is most active due to the difficulty in identifying the host galaxies. The installation of the Keck Cosmic Web Imager (KCWI), an integral field spectrograph, on Keck II has opened a new window to quickly identify galaxies via their Lyman alpha emission at this redshift. I will introduce a new survey to build a catalog of absorber-galaxy pairs at z=2-3 with KCWI. With the combination of HST images, high-resolution quasar spectra, and the cutting-edge KCWI data, this survey aims to examine CGM kinematics and metallicities and relate them to the host galaxy star formation rates and orientations to reveal the baryon cycle at cosmic noon. https://nmsu.zoom.us/j/96153330256
Transitioning to Industry from Academia,
A common career path for recent astronomy graduates with a PhD is data science, but it can be difficult to parse through the enormous amount of information on how exactly to transition to this career. I graduated from NMSU in 2019 and transitioned immediately to an industry career in data science. This talk will be a quick background on my career path, how students can get into data science, and what an industry career in data science actually looks like day-to-day.
A UV to IR Portrait of the Milky Way
Cat Fielder, University of Pittsburgh
Dynamical Regimes of Giant Planet Polar Vortices
Shawn Brueshaber,Western Michigan University
We present a numerical model that reveals a mechanism governing the polar atmospheric dynamics of
Jupiter, Saturn, Uranus and Neptune. Exploration of the polar regions of the gas giants has produced
surprisingly diverse results and these discoveries raise questions about the mechanism that
differentiates these polar atmospheric dynamics regimes. To help determine what physical mechanisms
control these differences, we use the Explicit Planetary Isentropic Coordinate (EPIC) model to carry
out forced-turbulence shallow-water simulations in a gamma-plane configuration using two sets of the
experiments. The first investigates the effects of three parameters, the planetary Burger number, Bu =
(Ld / a)2 (Ld is the Rossby deformation radius, a is the planetary radius), input storm strength, s, and the
storm polarity fraction (i.e., fraction of cyclonic and anticyclonic storms), α. The second set of
experiments focuses on the detailed circulation of the polar vortices by investigating the role of storm
size, storm intensity, and storm polarity fraction. The model is forced by small-scale stochastic mass
pulses that parametrically represent cumulus storms, widely thought to be an important mechanisms in
maintaining the vigorous circulation on giant planets.
Bu emerges to be the most important of the tested parameters, able to distinguish between four distinct
dynamical regimes, matching those of the giant planets, which from large to small Bu, are: i) a large
cyclonic polar vortex (i.e., Ice-Giant-Regime), ii) a compact intense cyclonic polar vortex (“Saturn-
Regime”), iii) two large vortices or one vortex offset from the pole (Transitional-Regime), and iv)
meandering jets with no centrally dominant vortex, or with multiple circumpolar cyclones (Jupiter-
Regime). The boundaries of these regimes are found to be only slightly modulated by the values of s
and α. By applying this correlation with respect to Bu in reverse, an observation of a particular polar
regime could in principle be used to constrain Ld.
Our results provide new key insights into the dynamics of solitary polar cyclones that emerge on giant
planets as a result of moist-convective forcing. We find that the wind speed of the polar cyclones within
Saturn- and Ice-Giant-Regimes is substantially influenced by storm size, storm wind speed, and storm
polarity fraction. The radius of the polar cyclone is also influenced by the storm polarity fraction, but,
is not influenced by the storm size or the storm wind speed. Our new results clarify the role of storm
forcing on the intensity and size of Saturn- and Ice-Giant-Regime polar cyclones.