Slitless spectrometers can provide simultaneous imaging and spectral data over an extended field of view, thereby allowing rapid data acquisition for extended sources. In some instances, when the object is greatly extended or the spectral dispersion is too small, there may be locations in the focal plane where emission lines at different wavelengths contribute. It is then desirable to unfold the overlapped regions in order to isolate the contributions from the individual wavelengths. In this paper, we describe a method for such an unfolding, using an inversion technique developed for an extreme ultraviolet imaging spectrometer and coronagraph named the COronal Spectroscopic Imager in the EUV (COSIE). The COSIE spectrometer wavelength range (18.6 -20.5 nm) contains a number of strong coronal emission lines and several density sensitive lines. We focus on optimizing the unfolding process to retrieve emission measure maps at constant temperature, maps of spectrally pure intensity in the Fe XII and Fe XIII lines and density maps based on both Fe XII and Fe XIII diagnostics.
Ancient, very metal-poor (VMP) stars offer a window into the earliest epochs of galaxy formation and assembly. We combine data from the H3 Spectroscopic Survey and Gaia to measure metallicities, abundances of α elements, stellar ages, and orbital properties of a sample of 482 VMP ([Fe/H] < −2) stars in order to constrain their origins. This sample is confined to 1 ≲ ∣Z∣ ≲ 3 kpc from the Galactic plane. We find that >70% of VMP stars near the disk are on prograde orbits and this fraction increases toward lower metallicities. This result is unexpected if metal-poor stars are predominantly accreted from many small systems with no preferred orientation, as such a scenario would imply a mostly isotropic distribution. Furthermore, we find there is some evidence for higher fractions of prograde orbits among stars with lower [α/Fe]. Isochrone-based ages for main-sequence turn-off stars reveal that these VMP stars are uniformly old (≈12 Gyr) irrespective of the α abundance and metallicity, suggesting that the metal-poor population was not born from the same well-mixed gas disk. We speculate that the VMP population has a heterogeneous origin, including both in situ formation in the ancient disk and accretion from a satellite with the same direction of rotation as the ancient disk at early times. Our precisely measured ages for these VMP stars on prograde orbits show that the Galaxy has had a relatively quiescent merging history over most of cosmic time, and implies the angular momentum alignment of the Galaxy has been in place for at least 12 Gyr.
Although there is little debate that Census data reveal declines in standard measures of segregation over the past several decades, depending on who you ask, racial residential segregation is either just about gone or is stubbornly persistent. In this study, we draw attention to how the murkiness in the conceptualization of what has replaced 'segregation' and the related question of what integration is, contributes to this disagreement. Through an analysis of attitudes toward racially integrated neighborhoods, we demonstrate the pitfalls of our lack of consistency and clarity about the conceptual and operational definition of integration. Our analysis reveals the diversity of attitudes toward integrated communitiesdepending on who is asked, and what kind of integration is considered-and points to a fragility of commitment to the ideals of integration. We do this by using an innovative survey dataset that includes both open and closed-ended questions asked of a large probability sample of Whites, African Americans, and Latinos living in the Chicago metropolitan area. The survey asked individuals to describe their ideal neighborhood racial/ethnic composition and explain why it was ideal; they were then asked to describe (and explain) their least desired neighborhood racial/ethnic composition. Juxtaposing the results, we reveal that integration is both enthusiastically endorsed and much maligned-even within the same person-and that whether it is good or bad very much depends on the type of integration. We argue that appreciating the diversity of integration attitudes is critical if we are to develop a more nuanced understanding of future patterns of residential stratification in our increasingly diverse nation.
This study examines the 21st-century Historically Black College and University (HBCU) presidency. First, we gathered information on the skills needed for the 21st century HBCU president. Then, we examined the background of future HBCU presidents. Through an analysis and discussion of the responses of current HBCU presidents, trustees,1 and presidential search consultants, we determined what skills are pertinent for HBCU presidential hopefuls to attain. Lastly, we made recommendations, based on our findings, regarding the skills needed for HBCU presidential aspirants to not only reach the presidency but to perform well upon doing so.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.