Abstract: (No Abstract).

Hello and welcome back to CASS Journal club! We want our first meeting of the school year to be an informal setting where everyone can meet the new faces, catch up on our lives, and maybe share a few tips and tricks on how to give a successful presentation. Pizza will be provided afterwards on the 4th floor balcony at 1pm. Looking forward to seeing everyone there!

Meeting ID: 943 0965 7830

 Abstract: (None).

Meeting ID: 946 2493 1312

One tap mobile
+16692192599,,94624931312# US (San Jose)
+16699006833,,94624931312# US (San Jose)

Dial by your location
+1 669 219 2599 US (San Jose)
+1 669 900 6833 US (San Jose)
+1 213 338 8477 US (Los Angeles)

Meeting ID: 946 2493 1312
Find your local number: https://ucsd.zoom.us/u/abAXF8Vlpw

 Abstract: The Keck All-sky Precision Adaptive Optics (KAPA) project is now entering year 5 of 5, aiming to upgrade the AO system at Keck. In this talk, I will kick things off with a brief history and the need for adaptive optics. Then I will dive into the science (art? black magic?) of Point Spread Function Reconstruction (or PSF-R), aimed especially for folks new to AO Systems - What is it, why is it so difficult and why do we even try. I will then describe the latest efforts in this area, including my own, to do PSF-R for the new Keck AO system in order to prepare us for the next age of EELTs. This will be a very broad talk, with no focus on a particular paper and will hopefully serve as an introduction to Adaptive Optics and PSF-R for the uninitiated. For those in the know, I will describe the science cases KAPA is going to tackle that make pursuing these technical achievements worthwhile.

Meeting ID: 972 1991 6669

One tap mobile
+16692192599,,97219916669# US (San Jose)
+16699006833,,97219916669# US (San Jose)

Dial by your location
+1 669 219 2599 US (San Jose)
+1 669 900 6833 US (San Jose)
+1 213 338 8477 US (Los Angeles)

Meeting ID: 972 1991 6669
Find your local number: https://ucsd.zoom.us/u/aeOJRRZoc

Lingfeng's Abstract: Abstract: The kinematics of star clusters, where most stars are born, provide valuable insights in the processes of their formation and evolution. The Orion Nebula Cluster (ONC), being the closest massive star cluster with active star formation within, is therefore an ideal target for studying the history of star clusters given its proximity and vitality. In this work, we analyze the kinematics of the stars within 4 arcminutes from the Trapezium, the heart of the ONC. Radial velocities are retrieved from spectroscopy data acquired by the Keck II NIRSPEC with adaptive optics. A kinematic map is then constructed by combining the proper motions previously measured by the Hubble Space Telescope. The measured one-dimensional velocity dispersion in is 2.24±0.08 km/s, higher than the virial equilibrium prediction of 1.71 km/s. This suggests that the ONC is supervirial. In addition, a negative correlation is detected between the relative velocity with respect to the neighbors of each star within a 0.1-pc radius and the interpolated stellar mass. Such a relation is not present between the velocity dispersion and stellar mass, indicating that energy equipartition has not yet occurred within the cluster. Therefore, low-mass stars moving faster than their surrounding stars in a supervirial cluster suggests that the initial mass of forming stars are related to their initial kinematic states. Furthermore, a counter-clockwise rotation is identified in the region.

Lingfeng's Abstract: Abstract: (Above; Daria's Abstract: TBD)

Meeting ID: 983 7451 0276

One tap mobile
+16699006833,,98374510276# US (San Jose)
+12133388477,,98374510276# US (Los Angeles)

Dial by your location
+1 669 900 6833 US (San Jose)
+1 213 338 8477 US (Los Angeles)
+1 669 219 2599 US (San Jose)

Meeting ID: 983 7451 0276
Find your local number: https://ucsd.zoom.us/u/asoRN2cjS

 Abstract: Direct imaging surveys over the past decade have led to the discovery of a number of Jupiter-like planets orbiting their host stars in wide orbits. These planets lie at distances of 9 −120 AU from their host stars and have masses around 2−14 MJ. The leading theories of planet formation — core accretion and gravitational instability — cannot easily explain the formation of these planets. A possible resolution to this paradox involves the comparison of elemental abundances (such as C/O ratios) for these giants with their host stars, with predictions of current theoretical models implying different planet-to-host star elemental abundance ratios depending on the formation mechanism. However, many of the hosts of directly imaged planets have poorly constrained abundances. Optical spectra of directly imaged planet host stars can be used to estimate elemental abundance ratios. To this end, we have started a comprehensive survey of directly imaged planet host stars to better constrain their abundances, primarily carbon and oxygen. The first results from this survey involve the use of carbon and oxygen lines to estimate the C/O ratio for the stars using spectral synthesis modeling and equivalent width analyses. We are able to estimate the abundances up to an accuracy of ~0.1 dex, and ℅ at an accuracy of up to 20%. This enables comparison of our results to carbon and oxygen abundances of the directly imaged planets obtained using direct imaging spectroscopy, which allows us to constrain their formation scenarios.

Meeting ID: 956 6403 8763

One tap mobile
+12133388477,,95664038763# US (Los Angeles)
+16692192599,,95664038763# US (San Jose)

Dial by your location
+1 213 338 8477 US (Los Angeles)
+1 669 219 2599 US (San Jose)
+1 669 900 6833 US (San Jose)

Meeting ID: 956 6403 8763
Find your local number: https://ucsd.zoom.us/u/abEthfjNjO