Rachael L. Merritt

Traditional physics laboratory courses often focus on experiments with well-known results, limiting students’ engagement in authentic scientific practices. Course-based undergraduate research experiences (CUREs), where students engage in real research with unknown outcomes, have been shown to support positive student outcomes, such as increased self-efficacy, persistence, and engagement in scientific practices. However, discipline-specific studies of CUREs in physics remain limited. We describe the development, structure, and initial implementation of a photovoltaics-focused CURE in a second-year undergraduate physics laboratory course at the University of Colorado Boulder. To examine how students experienced the course, we analyzed end-of-semester reflection assignments using the five CURE components (i.e., scientific practices, discovery, relevance, collaboration, and iteration), as well as established dimensions of research authenticity, as analytic frameworks. Students described experiences associated with all five CURE components, with collaboration, relevance, and scientific practices appearing most prominently in their reflections. Students also associated authentic research with meaningful scientific contribution, engagement in authentic scientific practices, and navigating the uncertainty and setbacks inherent in research, although fewer explicitly identified themselves as researchers or scientists. A subset of students additionally connected the course to their immediate thinking about future academic and professional pathways. This work contributes both a discipline-specific model for implementing CUREs in experimental physics laboratory courses and provides insight into how students interpret and experience authentic research within this course context.

We present an investigation of the Tully–Fisher (TF) relation solely for galaxies hosting an active galactic nucleus (AGN). Using 22 galaxies with primary, z -independent distances, we find that active galaxies exhibit significantly larger scatter about all TF relations compared to each respective calibration for (largely) inactive galaxies. The larger scatter persists despite removal of the AGN contamination from the photometry of the type 1 AGNs via (1) careful surface brightness decompositions or (2) employing spectral energy distributions to constrain the light contribution of the AGN. These results suggest that the influence of an AGN on its host galaxy’s surface brightness may extend beyond the nucleus. We also calculate the percentage difference between TF and primary distances and find that TF-based distances are biased toward overestimation of the primary distances to active galaxies by anywhere from ∼5% to 10% for the optical/near-infrared and ∼15% for distances predicted from inverting the baryonic TF relation. As TF-based distances (especially the I band) are relied on heavily for analysis and modeling of the local peculiar velocity ( V _PEC ) field, we suggest that active galaxies be removed from future V _PEC modeling samples.

Laboratory courses are essential in undergraduate physics education. The American Association of Physics Teachers recommends labs focus on developing students' experimental and professional skills, scientific reasoning, confidence, as well as other goals. Course-based undergraduate research experiences (CUREs) offer a promising approach to achieve these goals-providing authentic research opportunities to entire student cohorts while lowering barriers to research participation. However, few physics CUREs are documented in the literature. Broadly, our work aims to determine effective practices for developing and implementing physics CUREs. When developing a CURE, instructors should consider how to align course learning goals, such as engaging students in authentic research, with both the structural elements of a CURE and students' perceptions of those goals. Here, we examine how students engage with one aspect of authentic research, the idea of successful science, through an end-of-semester reflection assignment. We present the results of our analysis and compare how students in a CURE and those in a traditional lab course define successful science.

Undergraduate research experiences are beneficial students. However, the over-subscription of traditional research opportunities combined with other barriers prevent many students from participating. A promising alternative is a course-based undergraduate research experience, or CURE. CUREs are shown to have similar outcomes to traditional research experiences, while reducing the barriers to participation and providing an authentic research experience to an entire cohort of students. Within STEM disciplines, physics has been identified as underrepresented in CURE implementation. The broad scope of our work is to identify the challenges and opportunities for creating and sustaining physics CUREs. As a first step, we conducted a series of interviews with physics instructors from multiple institutions to collect faculty views on implementing and sustaining CUREs. We present the results from the analysis of these interviews and discuss barriers, learning goal priorities, and potential CURE benefits identified by instructors.

Undergraduate research has been shown to have many benefits for students, including degree persistence, feelings of belonging, and transferable research skills. However, there are barriers that prevent students' access to research experiences. Course-Based Undergraduate Research Experiences (CUREs) are a potential avenue to lower such barriers. Within STEM fields, physics has been identified as lacking CUREs, prompting our initiative to develop a physics framework to provide instructors with effective practices to develop their own CUREs. Understanding of students' perceptions of the connection between coursework and components of authentic research will inform the framework and assess impacts of course transformations. We probed student beliefs through writing assignments in a traditional lab course, exploring how authentic research elements were viewed in the context of the course.

Crustal cooling of accretion-heated neutron stars provides insight into the stellar interior of neutron stars. The neutron star X-ray transient, KS 1731−260, was in outburst for 12.5 years before returning to quiescence in 2001. We have monitored the cooling of this source since then through Chandra and XMM-Newton observations. Here we present a 150 ks Chandra observation of KS 1731−260 taken in 2015 August, about 14.5 years into quiescence and 6 years after the previous observation. We find that the neutron star surface temperature is consistent with the previous observation, suggesting that crustal cooling has likely stopped and the crust has reached thermal equilibrium with the core. Using a theoretical crust thermal evolution code, we fit the observed cooling curves and constrain the core temperature (T _c = 9.35 ± 0.25 × 10⁷ K), composition (Q ), and level of extra shallow heating required (Q _sh = 1.36 ± 0.18 MeV/nucleon). We find that the presence of a low thermal conductivity layer, as expected from nuclear pasta, is not required to fit the cooling curve well, but cannot be excluded either.