Optimal Integrated Abundances for Chemical Tagging of Extragalactic Globular Clusters

High resolution integrated light (IL) spectroscopy provides detailed abundances of distant globular clusters whose stars cannot be resolved. Abundance comparisons with other systems (e.g. for chemical tagging) require understanding the systematic offsets that can occur between clusters, such as those due to uncertainties in the underlying stellar population. This paper analyses high resolution IL spectra of the Galactic globular clusters 47 Tuc, M3, M13, NGC 7006, and M15 to (1) quantify potential systematic uncertainties in Fe, Ca, Ti, Ni, Ba, and Eu and (2) identify the most stable abundance ratios that will be useful in future analyses of unresolved targets. When stellar populations are well-modelled, uncertainties are ~0.1-0.2 dex based on sensitivities to the atmospheric parameters alone; in the worst case scenarios, uncertainties can rise to 0.2-0.4 dex. The [Ca I/Fe I] ratio is identified as the optimal integrated [alpha/Fe] indicator (with offsets <0.1 dex), while [Ni I/Fe I] is also extremely stable to within <0.1 dex. The [Ba II/Eu II] ratios are also stable when the underlying populations are well modelled and may also be useful for chemical tagging.Comment: 28 pages, 4 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Societ

The R-Process Alliance: A Comprehensive Abundance Analysis of HD 222925, a Metal-Poor Star with an Extreme R-Process Enhancement of [Eu/H] = -0.14

We present a detailed abundance analysis of the bright (V = 9.02), metal-poor ([Fe/H] = -1.47 +/- 0.08) field red horizontal-branch star HD 222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on 901 lines examined in a high-resolution optical spectrum obtained using the Magellan Inamori Kyocera Echelle spectrograph. We detect 28 elements with 38 <= Z <= 90; their abundance pattern is a close match to the Solar r-process component. The distinguishing characteristic of HD 222925 is an extreme enhancement of r-process elements ([Eu/Fe] = +1.33 +/- 0.08, [Ba/Eu] = -0.78 +/- 0.10) in a moderately metal-poor star, so the abundance of r-process elements is the highest ([Eu/H] = -0.14 +/- 0.09) in any known r-process-enhanced star. The abundance ratios among lighter (Z <= 30) elements are typical for metal-poor stars, indicating that production of these elements was dominated by normal Type II supernovae, with no discernible contributions from Type Ia supernovae or asymptotic giant branch stars. The chemical and kinematic properties of HD 222925 suggest it formed in a low-mass dwarf galaxy, which was enriched by a high-yield r-process event before being disrupted by interaction with the Milky Way.Comment: Accepted for publication in the Astrophysical Journal (17 pages, 4 figures, 3 tables

Trends in high life satisfaction among adolescents in five Nordic countries 2002–2014

Life satisfaction is an important indicator when assessing positive mental health aspects in populations, including among adolescents. The aim of this study was to investigate trends over time in prevalence of high life satisfaction among adolescents from five Nordic countries: Denmark, Iceland, Finland, Norway and Sweden. We used data from four waves of the Health Behaviour in School-Aged Children study from 2002, 2006, 2010 and 2014 (n=109,847). HBSC is a school-based study examining social circumstances, health and health behaviour among 11-, 13- and 15-years olds every four years in many European and North American countries. The Cantril Ladder, an 11-step visual analogue scale, was used as the measure of life satisfaction, and was dichotomised into two groups: high life satisfaction (scoring 9 or 10 on the scale) and medium/low life satisfaction (scoring <9). Over the 12-year period studied, between 28.6 and 44.8% of adolescents in the five countries rated their life satisfaction as high. Relatively large changes in prevalence levels occurred at the country level over the period. Denmark and Finland showed a steady, significant decline in the prevalence of high life satisfaction over the years. Iceland showed the highest prevalence in 2010. Norway and Sweden showed similar development until 2010, followed by a clear increase for Norway and a sharp decline in adolescent high life satisfaction for Sweden up until 2014. In all countries, high life satisfaction was most prevalent in 11-year- olds and least prevalent in almost all surveys among 15-year-old girls.peerReviewe