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Cho, Hyejeon,Blakeslee, John P.,Chies-Santos, Ana L.,Jee, M. James,Jensen, Joseph B.,Peng, Eric W.,Lee, Young-Wook American Astronomical Society 2016 The Astrophysical journal Vol.822 No.2
<P>We present new Hubble Space Telescope (HST) optical and near-infrared (NIR) photometry of the rich globular cluster (GC) system NGC 4874, the cD galaxy in the core of the Coma cluster (Abell 1656). NGC 4874 was observed with the HST Advanced Camera for Surveys in the F475W (g(475)) and F814W (I-814) passbands and with the Wide Field Camera. 3 IR Channel in F160W (H-160). The GCs in this field exhibit a bimodal optical color distribution with more than half of the GCs falling on the red side at g(475)-I-814 > 1. Bimodality is also present, though less conspicuously, in the optical-NIR I-814-H-160 color. Consistent with past work, we find evidence for nonlinearity in the g(475)-I-814 versus I-814-H-160 color-color relation. Our results thus underscore the need for understanding the detailed form of the color-metallicity relations in interpreting observational data on GC bimodality. We also find a very strong color-magnitude trend, or 'blue tilt,' for the blue component of the optical color distribution of the NGC 4874 GC system. A similarly strong trend is present for the overall mean I-814-H-160 color as a function of magnitude; for M-814 < -10 mag, these trends imply a steep mass-metallicity scaling with Z proportional to M-GC(1.4 +/- 0.4), but the scaling is not a simple power law and becomes much weaker at lower masses. As in other similar systems, the spatial distribution of the blue GCs is more extended than that of the red GCs, partly because of blue GCs associated with surrounding cluster galaxies. In addition, the center of the GC system is displaced by 4 +/- 1 kpc toward the southwest from the luminosity center of NGC 4874, in the direction of NGC 4872. Finally, we remark on a dwarf elliptical galaxy with a noticeably asymmetrical GC distribution. Interestingly, this dwarf has a velocity of nearly -3000 km s(-1) with respect to NGC 4874; we suggest it is on its first infall into the cluster core and is undergoing stripping of its GC system by the cluster potential.</P>
Zhou, Yuyu,Clarke, Leon,Eom, Jiyong,Kyle, Page,Patel, Pralit,Kim, Son H.,Dirks, James,Jensen, Erik,Liu, Ying,Rice, Jennie,Schmidt, Laurel,Seiple, Timothy Elsevier 2014 APPLIED ENERGY Vol.113 No.-
<P><B>Abstract</B></P> <P><B>Objective</B></P> <P>Because long-term socioeconomic transformation and energy service expansion show large spatial heterogeneity, advanced understanding of climate change impact on buildings energy use at the sub-national level will offer useful insights into climate policy and regional energy system planning.</P> <P><B>Methods</B></P> <P>In this study, we present a detailed buildings energy model with U.S. state-level representation, nested in an integrated assessment framework of the Global Change Assessment Model (GCAM). We project state-level buildings energy demand and its spatial pattern through the end of the century, considering the impact of climate change based on the estimates of heating and cooling degree days derived from downscaled USGS CASCaDE temperature data.</P> <P><B>Results</B></P> <P>The results indicate that climate change has a large impact on heating and cooling buildings energy and fuel use at the state level and that the 48 U.S. contiguous states exhibit a large spatial heterogeneity (ranges from −10% to+10% for total, −10% to+20% for electricity use and −20% to −5% for oil and gas use in the A2 scenario). Sensitivity analysis explores the potential implications of multiple driving forces, including climate action that would both change the price of energy and reduce climate change, the choice of climate models, and population and GDP growth. In addition, the 50-state building model is compared to a comparable version of the model which represents the entire United States as one region.</P> <P><B>Conclusions</B></P> <P>The study clearly demonstrates the spatially varying nature of fuel consumption changes that might occur from a changing climate. Although the study illustrates the importance of incorporating climate change into infrastructure-planning exercises, it also demonstrates that uncertainties about underlying drivers still must weigh heavily on these planning decisions. Finally, the study demonstrates that the 50-state building model provides both insights at the regional level and potentially better national-level estimates.</P> <P><B>Practice implication</B></P> <P>The findings from this study will help the climate-based policy decision and energy system, especially utility planning related to the buildings sector at the U.S. state and regional level facing the potential climate change.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Climate change has spatially heterogeneous impact on heating and cooling energy and fuel uses in building sector. </LI> <LI> Building energy and fuel uses are sensitive to other factors such as climate policy as well as climate change. </LI> <LI> The 50-state building model provides both insights at the regional level and potentially better national-level estimates. </LI> <LI> Climate change impact on building electricity use is critical, and needs to be incorporated in infrastructure planning. </LI> </UL> </P>