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JWST-TST High Contrast: JWST/NIRCam Observations of the Young Giant Planet β Pic b
Full text linkWe present the first JWST/NIRCam observations of the directly imaged gas giant exoplanet β Pic b. Observations in six filters using NIRCam\u27s round coronagraphic masks provide a high-signal-to-noise-ratio detection of β Pic b and the archetypal debris disk around β Pic over a wavelength range of ∼1.7-5 μm. This paper focuses on the detection of β Pic b and other potential point sources in the NIRCam data, following a paper by Rebollido et al. that presented the NIRCam and MIRI view of the debris disk around β Pic. We develop and validate approaches to obtaining accurate photometry of planets in the presence of bright, complex circumstellar backgrounds. By simultaneously fitting the planet’s point-spread function and a geometric model for the disk, we obtain planet photometry that is in good agreement with previous measurements from the ground. The NIRCam data support the cloudy nature of β Pic b’s atmosphere and the discrepancy between its mass as inferred from evolutionary models and the dynamical mass reported in the literature. We further identify five additional localized sources in the data, but all of them are found to be background stars or galaxies based on their color or spatial extent. We can rule out additional planets in the disk midplane above 1 M Jup outward of 2″ (∼40 au) and away from the disk midplane above 0.05 M Jup outward of 4″ (∼80 au). The inner giant planet β Pic c remains undetected behind the coronagraphic masks of NIRCam in our observations
VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab Formed Like a “Failed Star”
Full text linkYoung, low-mass brown dwarfs orbiting early-type stars, with low mass ratios (q ≲ 0.01), appear to be intrinsically rare and present a formation dilemma: could a handful of these objects be the highest-mass outcomes of “planetary” formation channels (bottom up within a protoplanetary disk), or are they more representative of the lowest-mass “failed binaries” (formed via disk fragmentation or core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, and when paired with wide wavelength coverage and accurate system age estimates, can constrain evolutionary models in a regime where the models have a wide dispersion depending on the initial conditions. We present new interferometric observations of the 16 Myr substellar companion HD 136164 Ab (HIP 75056 Ab) made with the Very Large Telescope Interferometer (VLTI)/GRAVITY and an updated orbit fit including proper motion measurements from the Hipparcos-Gaia Catalog of Accelerations. We estimate a dynamical mass of 35 ± 10 M J (q ∼ 0.02), making HD 136164 Ab the youngest substellar companion with a dynamical mass estimate. The new mass and newly constrained orbital eccentricity (e = 0.44 ± 0.03) and separation (22.5 ± 1 au) could indicate that the companion formed via the low-mass tail of the initial mass function. Our atmospheric fit to a SPHINX M-dwarf model grid suggests a subsolar C/O ratio of 0.45 and 3 × solar metallicity, which could indicate formation in a circumstellar disk via disk fragmentation. Either way, the revised mass estimate likely excludes bottom-up formation via core accretion in a circumstellar disk. HD 136164 Ab joins a select group of young substellar objects with dynamical mass estimates; epoch astrometry from future Gaia data releases will constrain the dynamical mass of this crucial object further
Linear Free Energy Relationships of the Iron- Catalyzed Oxidative α-Amination of Ketones
No full textLinear free energy relationships, such as the Hammett relationship and the Creary relationship, are frequently used as mechanistic probes. One relates the experimentally determined rates of reaction for differently substituted reagents to a predefined set of parameters for the substituents. The parameter set (e.g., Hammett, Hammett+, Hammett–, Creary) that gives the best linearization, and the slope of the linearization, reveal what is happening to the character of the intermediate in the rate determining step and the degree to which substituents affect the rate of reaction. Herein, these relationships are used to explore the rate determining step of the iron catalyzed oxidative α-amination of benzyl ketones with primary and secondary sulfonamides. The determined linearization will suggest whether the reaction proceeds via an α-carbocation, α-radical, and/or other reaction intermediates
Combinatorial Synthesis of Protein-Polymer Conjugates by Post-Polymerization Modification of Activated Ester Polymers
No full textNYC Community Schools and Student Crime Incidents
No full textA community school (CS) is a collaboration between school staff, families, youth, and the community to raise student educational outcomes. These schools increase access to resources such as physical and mental health services, guided extracurricular activities, leadership opportunities, parental and community engagement, and mentorship. Using data from New York City (NYC) and a difference-in-differences methodology, I find that CS decreases total crimes per 1000 students. This effect seems to be driven primarily by a decrease in other crimes and disciplinary infractions as well as concentrated in elementary schools
Episode 13: NRCS DC0910
Full text linkThis episode features three alums from the Class of 2010: Taylor Buono, Katy Kaproth-Gerecht, and Katie Wood. Along with their fourth teammate, Etta Grover-Silva, they collaborated with NRCS, the Natural Resources Conservation Service, on the design of a solar-powered microirrigation system for a two-acre farm. They also developed a design calculator to size solar arrays for similar farms
\u3ci\u3eMāyā and Mokṣa\u3c/i\u3e: Krishnachandra Bhattacharyya\u27s Spiritual Philosophy as a Vedāntin Critique of Kant
Full text linkThe Subject As Freedom (1930) is correctly regarded as Krishnachandra Bhattacharyya’s (henceforth KCB) magnum opus. This text relies on a set of ideas and evolves from a set of concerns that KCB develops more explicitly in two essays written both before and after that text, which might be regarded as its intellectual bookends. Those ideas are important and fascinating in their own right. They also illuminate KCB’s engagement with Kant and with the Vedānta tradition as well as his understanding of freedom itself, including its soteriological dimension. These two essays are “Saṅkara’s Doctrine of Māyā” (1930) and “The Advaita and Its Spiritual Significance” (1936).
While KCB drew insights from many Indian philosophical schools, his lodestone is Advaita Vedānta. Indeed, of all of his studies of the classical schools (each of which is contained in his Nachlass, edited by his son Gopinath), his Studies in Vedānta is the only one that was polished to the point that it can be considered a completed treatis
Extreme Ungrading: Rewilding the Classroom through Human-Centered Design
Full text linkAssessment in computer science education has grown reliant on rigid rubrics and intensive exams, a practice that yields capable yet compliant coders. In this article, I explore how we might use human-centered design to reexamine contemporary pedagogy and redesign our classrooms to cultivate a different type of programmer, one with a more critically engaged eye. Inspired by the ethos of agile development, I offer an alternative evaluation paradigm: Extreme Ungrading. Exploring results of a two-year case study applying this method to a software engineering class, this article distills actionable guidelines for enhancing learning outcomes through inclusive course development, and seeks to spark debate about our duty as scholars of HCI to reshape computer science education
Celebrating Faculty Scholarship 2024
Full text linkScroll down to view the bibliography of selected scholarly and creative work produced by Smith College faculty and submitted by faculty for the 2024 celebration which took place in the Neilson Library Skyline Reading Room, Smith College on April 25, 2024.https://scholarworks.smith.edu/celebratingfacultyscholarshipbiblios/1002/thumbnail.jp