Multi-epoch Direct Imaging and Time-Variable Scattered Light Morphology of the HD 163296 Protoplanetary Disk

We present H-band polarized scattered light imagery and JHK high-contrast spectroscopy of the protoplanetary disk around HD 163296 observed with the High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) and Subaru Coronagraphic Extreme Adaptive Optics (SCExAO)/Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) instruments at Subaru Observatory. The polarimetric imagery resolve a broken ring structure surrounding HD 163296 that peaks at a distance along the major axis of 0.”65 (66 au) and extends out to 0.”98 (100 au) along the major axis. Our 2011 H-band data exhibit clear axisymmetry, with the NW and SE side of the disk exhibiting similar intensities. Our data are clearly different from 2016 epoch H-band observations of the Very Large Telescope (VLT)/Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), which found a strong 2.7× asymmetry between the NW and SE side of the disk. Collectively, these results indicate the presence of time-variable, non-azimuthally symmetric illumination of the outer disk. While our SCExAO/CHARIS data are sensitive enough to recover the planet candidate identified from NIRC2 in the thermal infrared (IR), we fail to detect an object with JHK brightness nominally consistent with this object. This suggests that the candidate is either fainter in JHK bands than model predictions, possibly due to extinction from the disk or atmospheric dust/clouds, or that it is an artifact of the data set/data processing, such as a residual speckle or partially subtracted disk feature. Assuming standard hot-start evolutionary models and a system age of 5 Myr, we set new, direct mass limits for the inner (outer) Atacama Large Millimeter/submillimeter Array (ALMA)-predicted protoplanet candidate along the major (minor) disk axis of of 1.5 (2) M_J

THE UNIQUE GEOMETRIES AND ILLUMINATIONS OF PROTOPLANETARY DISKS AND THEIR POTENTIAL EXOPLANETS

The discovery of new protoplanetary disk structures can help reveal the dynamics of the young planetary systems and potentially point to planet formation within the disk. In my dissertation, I present investigations of three stellar/sub-stellar systems; DoAr 28, VHS J125601.92-125723.9 (VHS 1256), and HD 163296. First, I will discuss the first near-IR scattered light detection of the protoplanetary disk around DoAr 28. I modeled both the observed SED and H-band PI imagery of the system and found that our best fit models have a partially depleted inner gap from the dust sublimation radius out to ~8 au. Second, I present and analyze Subaru/IRCS L' and M' images of the nearby M dwarf VHS 1256, which was recently claimed to have a ~11 Mjup companion (VHS 1256 b). I found that the central star is a binary and conclude that VHS 1256 is most likely a very low mass (VLM) hierarchical triple system. Finally, I present Subaru/HiCIAO H-band imagery, Subaru/SCExAO near-IR imagery, and HST/STIS optical imagery of the protoplanetary disk around HD 163296. I demonstrate that the new Subaru/HiCIAO and HST/STIS imagery exhibits disk illumination variability on timescales < 3 months, possibly due to a non-axisymmetric distribution of dust clouds. show that our SCExAO/CHARIS observations fail to recover the previously identified 6-7 Mjup planetary candidate. Additionally, I did not detect the predicted launch of a new HH-knot nor did I detect any of the previously observed HH-knots, suggesting a potential change in the jet of HD 163296

Transcript for Episode 19: Legislative Legacy: 1972 Constitution Brings Legislature Closer to the People

https://digitalcommons.mtech.edu/crucible_transcriptions/1018/thumbnail.jp

Summary of Space Environment Magnetometer and Particle Replacement Experiment (SEMPRE) Study

As part of the GOES-R series follow on architecture study following the NOAA Satellite Observing System Architecture (NSOSA) study, a study team evaluated the feasibility of accommodating the GOES in-situ instruments (Magnetometer and Particle Detectors) on a dedicated spacecraft with no impact to the overall baseline mission cost assuming two large observatories. The accommodations cost on a primary operational type observatory are non-negligible requiring: a large non-magnetic boom to reduce the impact of the spacecraft interference on the magnetometer; and strict contamination control and magnetic cleanliness to prevent magnetic contamination near the magnetometers. These, along with the additional interface complexities greatly increase the cost of larger spacecraft by extending integration time with a large marching army. By contrast, a dedicated mission provides flexibility in location and refresh rate not afforded when these sensors are launched as secondary payloads. This study performed an informal industry survey of small form-factor instruments currently flying or in process of being developed. The study identified three potential particle detector suites and multiple magnetometers that will satisfy the requirements while having low enough volume and mass to allow accommodation on a rideshare class spacecraft. Using the largest of the identified particle detector suites, the Goddard Space Flight Center Mission Design Lab developed a design for a rideshare spacecraft that will accommodate the particle detector suite and magnetometer. The cost of the spacecraft, based on multiple cost models, is comparable to the cost of accommodating the magnetometer and particle detector suite on two (East and West) larger main observatories

Allosteric interactions of DNA and nucleotides with S. cerevisiae RSC

RSC, Remodel the Structure of Chromatin, is an essential chromatin remodeler of Saccharomyces cerevisiae that has been shown to have DNA translocase properties. We studied the DNA binding properties of a ‘trimeric minimal RSC’ (RSCt) of the RSC chromatin remodeling complex and the effect of nucleotides on this interaction using fluorescence anisotropy. RSCt binds to 20 bp fluorescein labeled double stranded DNA with a Kd of approximately 100 nM. The affinity of RSCt for DNA is reduced in the presence of AMP-PNP and ADP in a concentration dependent manner with the addition of AMP-PNP having the more pronounced effect. These differences in the magnitude at which the binding of ADP and AMP-PNP affect the affinity of DNA binding by RSCt suggests that the physical movement of the enzyme along DNA begins between the binding of ATP and its subsequent hydrolysis. Furthermore, the fact that the highest affinity for DNA binding by RSCt occurs in the absence of bound nucleotide offers a mechanistic explanation for the low apparent processivity of DNA translocation by the enzyme.This work was supported by National Institutes of Health Grant P20 RR017708 to C.J.F. and NIH GM60415 to B.R.C. Evan Rich was supported, in part, by an Undergraduate Research Award provided by the Kansas University Honors Program