Generic conditions for stable hybrid stars

We study the mass-radius curve of hybrid stars, assuming a single first-order phase transition between nuclear and quark matter, with a sharp interface between the quark matter core and nuclear matter mantle. We use a generic parameterization of the quark matter equation of state, which has a constant, i.e. density-independent, speed of sound ("CSS"). We argue that this parameterization provides a framework for comparison and empirical testing of models of quark matter. We obtain the phase diagram of possible forms of the hybrid star mass-radius relation, where the control parameters are the transition pressure, energy density discontinuity, and the quark matter speed of sound. We find that this diagram is sensitive to the quark matter parameters but fairly insensitive to details of the nuclear matter equation of state. We calculate the maximum hybrid star mass as a function of the parameters of the quark matter EoS, and find that there are reasonable values of those parameters that give rise to hybrid stars with mass above $2\,M_\odot$.Comment: 11 pages, 8 figures. Changes to nomenclature, references adde

Phase conversion dissipation in multicomponent compact stars

We propose a mechanism for the damping of density oscillations in multicomponent compact stars. The mechanism is the periodic conversion between different phases, i.e., the movement of the interface between them, induced by pressure oscillations in the star. The damping grows nonlinearly with the amplitude of the oscillation. We study in detail the case of r-modes in a hybrid star with a sharp interface, and we find that this mechanism is powerful enough to saturate the r-mode at very low saturation amplitude, of order $10^{-10}$, and is therefore likely to be the dominant r-mode saturation mechanism in hybrid stars with a sharp interface.Comment: 17 pages, 8 figures. Typos in Eq. (15), Eqs. (64)-(65) and Eqs. (B4)-(B5) correcte

Signatures for quark matter from multi-messenger observations

We review the prospects for detecting quark matter in neutron star cores. We survey the proposed signatures and emphasize the importance of data from neutron star mergers, which provide access to dynamical properties that operate on short timescales that are not probed by other neutron star observables.Comment: 23 pages, 4 figures; refs. added, accepted for publicatio

Early Childhood Educators\u27 Understanding and Perspectives of Music Therapy

Few research studies have explored early childhood educators’ understanding and perspectives of music therapy. In this study, 28 early childhood educators were surveyed, answering open- and closed-ended questions relating to what they understand about and how they perceive the profession of music therapy. Descriptive statistics were used to analyze quantitative data and thematic analysis to analyze qualitative data. Quantitative data highlighted the little education provided to early childhood educators about music therapy and suggests that very few early childhood educators have worked with music therapists. The three participants who had worked with a music therapist reported that music therapy has been beneficial for their students. Thematic findings revealed that early childhood educators would like to see more collaboration between music therapists and early childhood educators as well as resources to learn more about music therapy. Additional research should be done to explore early childhood educators’ understanding and perspectives of music therapy with a larger sample as well as learn in which parts of the country music therapy in early childhood education is most common and what resources would be most helpful in providing education about music therapy

Hassel, H., Launius, C., & Rensing, S. (2021). A Guide to Teaching Introductory Women’s and Gender Studies: Socially Engaged Classrooms. Springer International Publishing. 133 pp. $24.99 eBook. DOI: https://doi.org/10.1007/978-3-030-71785-8.

In A Guide to Teaching Introductory Women’s and Gender Studies: Socially Engaged Classrooms (2021), authors Holly Hassel, Christie Launius, and Susan Rensing draw on their years of experience designing and teaching introductory courses to Women’s and Gender Studies (WGS) and on the insights of key feminist educators. Their writing style is engaging and approachable, and they succeed at addressing the concerns of both students and teachers by taking into account the growing demographic diversity in WGS classrooms. Educators within the field of WGS–graduate students, new faculty, and experienced professors–will find within this text a rich range of pedagogical materials that can be tailored to a variety of different educational settings

Modeling High-Altitude Nuclear Detonations using Existing Ionospheric Models

One threat to the United States is a nuclear weapon being detonated at high altitude over the country. The resulting electromagnetic pulse (EMP) could devastate the nation. Despite its destructive nature, the response of the ionosphere to such an event is poorly understood. This study assesses if existing ionospheric models, which are used to nowcast and forecast ionospheric changes, can be used to model the response to a high-altitude nuclear detonation (HAND). After comparing five ionosphere models, the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) was selected and modified to incorporate an array of F10.7 indices to serve as a proxy for the localized heightened extreme ultraviolet activity and, using the temperature of the fireball attenuated over distance, drive the chemistry. It was found that the modified model had an increase in electron content over the standard model that was in good agreement with the changes resulting from a geomagnetic storm. However, the examined ionospheric models are not sufficient to simulate the effects of a HAND due to the limitations in the models\u27 calculations