2019, Hill, Vanessa, Skúladóttir, Ása, Tolstoy, Eline, Venn, Kim A., Shetrone, Matthew D., Jablonka, Pascale, Primas, Francesca, Battaglia, Giuseppina, de Boer, Thomas J. L., François, Patrick, Helmi, Amina, Kaufer, Andreas, Letarte, Bruno, Starkenburg, Else, Spite, Monique

We present detailed chemical abundances for 99 red-giant branch stars in the centre of the Sculptor dwarf spheroidal galaxy, which have been obtained from high-resolution VLT/FLAMES spectroscopy. The abundances of Li, Na, -elements (O, Mg, Si, Ca Ti), iron-peak elements (Sc, Cr, Fe, Co, Ni, Zn), and r- and s-process elements (Ba, La, Nd, Eu) were all derived using stellar atmosphere models and semi-automated analysis techniques. The iron abundances populate the whole metallicity distribution of the galaxy with the exception of the very low metallicity tail, 2:3 [Fe/H] 0:9. There is a marked decrease in [ /Fe] over our sample, from the Galactic halo plateau value at low [Fe/H] and then, after a “knee”, a decrease to sub-solar [ /Fe] at high [Fe/H]. This is consistent with products of core-collapse supernovae dominating at early times, followed by the onset of supernovae type Ia as early as 12 Gyr ago. The s-process products from low-mass AGB stars also participate in the chemical evolution of Sculptor on a timescale comparable to that of supernovae type Ia. However, the r-process is consistent with having no time delay relative to core-collapse supernovae, at least at the later stages of the chemical evolution in Sculptor. Using the simple and well-behaved chemical evolution of Sculptor, we further derive empirical constraints on the relative importance of massive stars and supernovae type Ia to the nucleosynthesis of individual iron-peak and -elements. The most important contribution of supernovae type Ia is to the iron-peak elements: Fe, Cr, and Mn. There is, however, also a modest but non-negligible contribution to both the heavier -elements: S, Ca and Ti, and some of the iron-peak elements: Sc and Co. We see only a very small or no contribution to O, Mg, Ni, and Zn from supernovae type Ia in Sculptor. The observed chemical abundances in Sculptor show no evidence of a significantly di erent initial mass function, compared to that of the Milky Way. With the exception of neutron-capture elements at low [Fe/H], the scatter around mean trends in Sculptor for [Fe=H] 2:3 is extremely low, and compatible with observational errors. Combined with the small scatter in the age-elemental abundances relation, this calls for an effcient mixing of metals in the gas in the centre of Sculptor since 12 Gyr ago.

2019, Ysseldyk, Renate, Greenaway, Katharine H., Hassinger, Elena, Zutrauen, Sarah, Lintz, Jana, Bhatia, Maya P., Frye, Margaret, Starkenburg, Else, Tai, Vera

Several challenges (e.g., sexism, parental leave, the glass ceiling, etc.) disproportionately affect women in academia (and beyond), and thus perpetuate the leaky pipeline metaphor for women who opt-out of an academic career. Although this pattern can be seen at all levels of the academic hierarchy, a critical time for women facing such challenges is during the postdoctoral stage, when personal life transitions and professional ambitions collide. Using a social identity approach, we explore factors affecting the mental health of postdoctoral women, including identity development (e.g., as a mother, a scientist) and lack of control (uncertainty about one’s future personal and professional prospects), which likely contribute to the leak from academia. In this mixed-method research, Study 1 comprised interviews with postdoctoral women in North America (n = 13) and Europe (n = 8) across a range disciplines (e.g., psychology, physics, political science). Common themes included the negative impact of career uncertainty, gender-based challenges (especially sexism and maternity leave), and work-life balance on mental and physical health. However, interviewees also described attempts to overcome gender inequality and institutional barriers by drawing on support networks. Study 2 comprised an online survey of postdoctoral women (N = 146) from a range of countries and academic disciplines to assess the relationships between social identification (e.g., disciplinary, gender, social group), perceived control (i.e., over work and life), and mental health (i.e., depression, anxiety, stress, and life satisfaction). Postdoctoral women showed mild levels of stress and depression, and were only slightly satisfied with life. They also showed only moderate levels of perceived control over one’s life and work. However, hierarchical regression analyses revealed that strongly identifying with one’s discipline was most consistently positively associated with both perceived control and mental health. Collectively, these findings implicate the postdoctoral stage as being stressful and tenuous for women regardless of academic background or nationality. They also highlight the importance of disciplinary identity as a potentially protective factor for mental health that, in turn, may diminish the rate at which postdoctoral women leak from the academic pipeline.

2017, Oman, Kyle, Starkenburg, Else, Navarro, Julio

The stellar halos of galaxies encode their accretion histories. In particular, the median metallicity of a halo is determined primarily by the mass of the most massive accreted object. We use hydrodynamical cosmological simulations from the APOSTLE project to study the connection between the stellar mass, the metallicity distribution, and the stellar age distribution of a halo and the identity of its most massive progenitor. We find that the stellar populations in an accreted halo typically resemble the old stellar populations in a present-day dwarf galaxy with a stellar mass ~0.2-0.5 dex greater than that of the stellar halo. This suggests that had they not been accreted, the primary progenitors of stellar halos would have evolved to resemble typical nearby dwarf irregulars.