Code of Conduct
Everyone is expected to abide by the following code of conduct in their online interactions with others (via Slack or Zoom).
The success of the KNAC meeting relies on vigorous scientific and technical discourse within a framework of respect for all participants. KNAC will not tolerate harassment, bullying, or persistent unwelcome behavior of one individual or group against another. An individual who wishes to raise a concern about inappropriate behavior should contact Karen Masters (klmasters at haverford dot edu), or any other member of the consortium that they trust.
Moderator: Dave Stark (Haverford)
Atomic hydrogen (HI) in galaxies is measured with its 21cm line emission that can be detected using telescopes like the 100m Green Bank Telescope, a single dish radio telescope. This signal has a large wavelength so detections are spatially unresolved, but the Doppler shift spreads the 21cm line across a range of observable frequencies. These are HI global profiles. In this work we aim to explore their shapes, and then attempt to recover HI radial profiles in galaxies with measured rotation curves from the HI-MaNGA survey. We present a model HI global profile, in an idealized situation, which can be used for symmetric HI global profiles pulled from the HI-MaNGA data. We use the correlation between HI flux and HI radius, and model the dependence of HI surface density with radius as a truncated exponential with a scale length set by the total HI mass in the given galaxy. We use fits to the rotation from MaNGA. Future work will investigate further how well our model can be used to find the best for HI radial profile in real, raw data that is not idealized.
Moderator: Daniel Grin (Haverford)
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has become the leading instrument for detecting Fast Radio Bursts (FRBs). With CHIME as the primary telescope for detecting FRBs, CHIME/FRB Outriggers will use very-long-baseline interferometry (VLBI) in order to localize these events. Localization errors due to internal clock delay must be minimized in order to stay true to CHIME/FRB Outrigger’s goal of milliarcsecond precision. This paper discusses the techniques used to decide which clocks will be installed at outrigger stations. Additionally, the resulting pipeline significantly improves clock performance and provides calibration methods for clocks that do not initially meet CHIME/FRB Outriggers’ stability requirements for VLBI.
1308+326 is a well-studied BL Lacertae object most-often cited for its high luminosity optical burst spanning the late 1970s into the early 1980s. Observations became less frequent as the brightness decreased in the 1990s. The Foggy Bottom Observatory at Colgate University started observing the object at that time and has continued up through the present, providing invaluable data on 1308+326 at times when few other observatories watched it. At the Foggy Bottom Observatory, preliminary photometric measurements are made each night from unre- duced images of each quasar as we are observing it, but formal reductions to produce reliable magnitude measurements are made afterwards with AstroImageJ, using object images, darks, and skyflats, including biases when necessary. We performed a thorough literature search to find every source referencing 1308+326. These data were used to supplement observations made at FBO to create the most complete optical light curve to date. Using this long-term light curve, we were able to analyze the periodicity of this object, primarily through Lomb-Scargle and Structure Function analyses. From this, we found a relatively strong period of 22 years, which is promising, but also necessitates further research and analysis on this object.
Using data from the rapidly-rotating and highly magnetized neutron stars (pulsars) PSR B1937+21 and B0531+21, this paper calculates and constrains scintillation parameters of both pulsars as well as the relative distances to the screens causing the scattering effects, assuming a thin screen model and a homogeneous Kolmogorov electron density spectrum. These values are obtained in the hopes of better understanding the large- and small-scale structure of the interstellar medium and searching for areas of improvement in current Galactic electron density models in order to further the efforts of pulsar timing arrays.
Protoplanetary disks are disks of gas and dust that surround newly-formed stars. The structure and evolution of these objects determine how planet formation proceeds; studying how protoplanetary disks vary with age, structure, and region will provide us with clues to the origin and properties of planets around other stars and within our own solar system. The goal of our research was to uniformly model protoplanetary disks in the star-forming regions Chameleon II and Taurus in order to complete a database of disk structure that can be used to study planet formation across star-forming regions. The disks in Chameleon II (n=24) and Taurus (n=49) were imaged using observations from the Atacama Large Millimeter/sub- millimeter Array (ALMA) at 1.33 mm wavelength and the Submillimeter Array (SMA) at 0.869 mm, respectively, with angular resolution for most disks being approximately 0′.′35. An affine invariant Markov chain Monte Carlo (MCMC) algorithm was used to fit the disks for 8 parameters: flux, characteristic radius, inclination, position angle, and offset position (right ascension and declination), as well as the slope of a power law γ1 and exponential tail γ2 which describe the flux as a function of radius in the inner and outer disk, respectively. This database will be used to study the conditions that influence planet formation to help us better understand the evolution of planetary systems.
Class 0 Source CARMA-7 in Serpens South
Makoto Johnstone, Middlebury
Previous observations of CARMA-7, a low mass Class 0 protostar in the Serpens South cluster region, detected episodic ejection events traced by 12CO. Other than carbon monoxide isotopologues, however, little is known about the abundances and morphologies of molecular lines around the source. We present Band 6 observations of 9 molecular emission lines near CARMA-7 using the Atacama Large Millimeter/sub-millimeter Array (ALMA). We confirm the presence of a bipolar outflow extending in the north-south direction (P.A. 4◦) as traced by 12CO and H2CO. Further investigation of the H2CO line uncovered a low-velocity emission feature extending to the southwest (P.A. 72◦). We interpret this feature as a potential accretion flow, but further analysis via modeling is necessary. The C18O emission line shows early signs of Keplerian rotation in the disk/envelope. However, other known disk and envelope tracers such as 13CO and N2D+ fail to show signs of rotation. We find that CARMA-7 does not hold a disk larger than 305 AU and that the detection of a strong outflow is not a clear indicator of an evolved rotating disk.
Moderator: Seth Redfield (Wesleyan)
The goal of this research is to look for exoplanets orbiting white dwarf stars. This project serves as a jumping off point for future research using the 24” telescope at the Van Vleck Observatory. We narrow down a large data release to look at just the white dwarf stars that have heavy metals observed in their spectra, are visible from the Van Vleck Observatory, and have not already been observed in depth by other survey telescopes. As of now, 93% of the white dwarf stars in the latest Gaia release have been observed for substantial periods of time by TESS, Kepler, or K2. Of the remaining 52 unobserved stars that also have polluted spectra, we focus mainly on the star LB 1188 and are able to conclude with 100% confidence that LB 1188 does not have a transit with a period less than 5.3 hours and 70% confidence out to half a day. Future work will focus on expanding observations to new stars and continuing observations on the stars covered by this project.
We catalogue and analyze Gale crater’s diagenetic concretions–features created during its post-lacustrine aqueous events–from MSL Curiosity Rover MAHLI and Mastcam observations, Sols 1900-3049. Notably, we observe few to no concretions in the clay-rich Glen Torridon region, and a correlation between concretion presence and geomorphic unit. Moreover, Mast- cam multispectral data from Sols 2850-3049 may indicate a correlation between concretion morphology and spectral properties.