The nitty gritty of South Carolina soil orders

Detailed information on soil orders of South Carolina is available but not in a digestible format for various state stakeholders. The goal of this first-semester Creative Inquiry is to develop stakeholder appropriate tools regarding general soil characteristics of South Carolina. A poster and interactive Web map depicting and explaining the soil orders of South Carolina are the first tools produced. Both the poster and Web map are targeted for K-12 teachers as teaching aids and will accompany a lesson plan for meeting school standards. The Web map will also be available for the public to use in exploring the soil orders of South Carolina. By the end of the first semester, students will determine complete lesson plans and present a lesson to two 7th grade science classes, and will identify at what classification level will soil attributes be used to integrate in to the interactive Web map

The effects of dynamical substructure on Milky Way mass estimates from the high velocity tail of the local stellar halo

We investigate the impact of dynamical streams and substructure on estimates of the local escape speed and total mass of Milky Way-mass galaxies from modelling the high velocity tail of local halo stars. We use a suite of high-resolution, magneto-hydrodynamical cosmological zoom-in simulations, which resolve phase space substructure in local volumes around solar-like positions. We show that phase space structure varies significantly between positions in individual galaxies and across the suite. Substructure populates the high velocity tail unevenly and leads to discrepancies in the mass estimates. We show that a combination of streams, sample noise and truncation of the high velocity tail below the escape speed leads to a distribution of mass estimates with a median that falls below the true value by $\sim 20 \%$, and a spread of a factor of 2 across the suite. Correcting for these biases, we derive a revised value for the Milky Way mass presented in Deason et al. of $1.29 ^{+0.37}_{-0.47} \times 10^{12}$ $\rm M_{\odot}$.Comment: Re-submitted to MNRAS Letters after minor revisio

A Forum for Business Growth and Workforce Development: Findings and Recommendations

In the fall of 2008, Illinois State University – Extended University (EU) and the Economic Development Council of the Bloomington-Normal Area (EDC) initiated discussions about a community partnership project to identify workforce opportunities and challenges related to economic stabilization and growth in order to gain a better understanding of the state of workforce preparedness in the area. Rapidly changing dynamics in the economy made previous assessments obsolete. Organizations who work toward the promotion of a strong workforce were approached to participate in the project. EU and the EDC were joined in sponsoring a community event by Heartland Community College, Illinois Wesleyan University, Lincoln College – Normal, Regional Office of Education 17, McLean County Chamber of Commerce, CareerLink 16, and the Small Business Development Center at Illinois State University. Project partners designed and developed a series of discussion forums for eight sectors: Agriculture and Energy, Manufacturing, Small Business Retail, Service, Financial Services, Information Technology, Healthcare, and Construction. The Forum for Business Growth and Workforce Development was held from June 8 – 12, 2009 at Illinois State University. Each sector panel discussion was moderated over a ninety minute period and included two to seven panelists from area businesses

Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations

We present and analyse mock stellar catalogues that match the selection criteria and observables (including uncertainties) of the Gaia satellite data release 2 (DR2). The source are six cosmological high-resolution magneto-hydrodynamic ΛCDM zoom simulations of the formation of Milky Way analogues from the AURIGA project. Mock data are provided for stars with V 20 deg. The mock catalogues are made using two different methods: the public SNAPDRAGONS code, and a method based on that of Lowing et al. (2015) that preserves the phase-space distribution of the model stars. These publicly available catalogues contain five-parameter astrometry, radial velocities, multiband photometry, stellar parameters, dust extinction values, and uncertainties in all these quantities. In addition, we provide the gravitational potential and information on the origin of each star. By way of demonstration, we apply the mock catalogues to analyses of the young stellar disc and the stellar halo. We show that (i) the young outer stellar disc exhibits a flared distribution that is detectable in the height and vertical velocity distribution of A - and B -dwarf stars up to radii of ∼15 kpc, and (ii) the spin of the stellar halo out to 100 kpc can be accurately measured with Gaia DR2 RR Lyrae stars. These catalogues are well suited for comparisons with observations and should help to (i) develop and test analysis methods for the Gaia DR2 data, (ii) gauge the limitations and biases of the data, and (iii) interpret the data in the light of theoretical predictions from realistic ab initio simulations of galaxy formation in the ΛCDM cosmological model

The merger that led to the formation of the Milky Way's inner stellar halo and thick disk

The assembly process of our Galaxy can be retrieved using the motions and chemistry of individual stars. Chemo-dynamical studies of the nearby halo have long hinted at the presence of multiple components such as streams, clumps, duality and correlations between the stars' chemical abundances and orbital parameters. More recently, the analysis of two large stellar surveys have revealed the presence of a well-populated chemical elemental abundance sequence, of two distinct sequences in the colour-magnitude diagram, and of a prominent slightly retrograde kinematic structure all in the nearby halo, which may trace an important accretion event experienced by the Galaxy. Here report an analysis of the kinematics, chemistry, age and spatial distribution of stars in a relatively large volume around the Sun that are mainly linked to two major Galactic components, the thick disk and the stellar halo. We demonstrate that the inner halo is dominated by debris from an object which at infall was slightly more massive than the Small Magellanic Cloud, and which we refer to as Gaia-Enceladus. The stars originating in Gaia-Enceladus cover nearly the full sky, their motions reveal the presence of streams and slightly retrograde and elongated trajectories. Hundreds of RR Lyrae stars and thirteen globular clusters following a consistent age-metallicity relation can be associated to Gaia-Enceladus on the basis of their orbits. With an estimated 4:1 mass-ratio, the merger with Gaia-Enceladus must have led to the dynamical heating of the precursor of the Galactic thick disk and therefore contributed to the formation of this component approximately 10 Gyr ago. These findings are in line with simulations of galaxy formation, which predict that the inner stellar halo should be dominated by debris from just a few massive progenitors.Comment: 19 pages, 8 figures. Published in Nature in the issue of Nov. 1st, 2018. This is the authors' version before final edit

Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing

We study the shapes of galaxy dark matter haloes by measuring the anisotropy of the weak gravitational lensing signal around galaxies in the second Red-sequence Cluster Survey (RCS2). We determine the average shear anisotropy within the virial radius for three lens samples: all galaxies with 19<m_r'<21.5, and the `red' and `blue' samples, whose lensing signals are dominated by massive low-redshift early-type and late-type galaxies, respectively. To study the environmental dependence of the lensing signal, we separate each lens sample into an isolated and clustered part and analyse them separately. We also measure the azimuthal dependence of the distribution of physically associated galaxies around the lens samples. We find that these satellites preferentially reside near the major axis of the lenses, and constrain the angle between the major axis of the lens and the average location of the satellites to =43.7 deg +/- 0.3 deg for the `all' lenses, =41.7 deg +/- 0.5 deg for the `red' lenses and =42.0 deg +/- 1.4 deg for the `blue' lenses. For the `all' sample, we find that the anisotropy of the galaxy-mass cross-correlation function =0.23 +/- 0.12, providing weak support for the view that the average galaxy is embedded in, and preferentially aligned with, a triaxial dark matter halo. Assuming an elliptical Navarro-Frenk-White (NFW) profile, we find that the ratio of the dark matter halo ellipticity and the galaxy ellipticity f_h=e_h/e_g=1.50+1.03-1.01, which for a mean lens ellipticity of 0.25 corresponds to a projected halo ellipticity of e_h=0.38+0.26-0.25 if the halo and the lens are perfectly aligned. For isolated galaxies of the `all' sample, the average shear anisotropy increases to =0.51+0.26-0.25 and f_h=4.73+2.17-2.05, whilst for clustered galaxies the signal is consistent with zero. (abridged)Comment: 28 pages, 23 figues, accepted for publication in A&

Balancing mass and momentum in the Local Group

In the rest frame of the Local Group (LG), the total momentum of the Milky Way (MW) and Andromeda (M31) should balance to zero. We use this fact to constrain new solutions for the solar motion with respect to the LG centre-of-mass, the total mass of the LG, and the individual masses of M31 and the MW. Using the set of remote LG galaxies at $>350$ kpc from the MW and M31, we find that the solar motion has amplitude $V_{\odot}=299\pm 15 {\rm ~km~s^{-1}}$ in a direction pointing toward galactic longitude $l_{\odot}=98.4^{\circ}\pm 3.6^{\circ}$ and galactic latitude $b_{\odot}=-5.9^{\circ}\pm 3.0^{\circ}$. The velocities of M31 and the MW in this rest frame give a direct measurement of their mass ratio, for which we find $\log_{10} (M_{\rm M31}/M_{\rm MW})=0.36 \pm 0.29$. We combine these measurements with the virial theorem to estimate the total mass within the LG as $M_{\rm LG}=(2.5\pm 0.4)\times 10^{12}~{\rm M}_{\odot}$. Our value for $M_{\rm LG}$ is consistent with the sum of literature values for $M_{\rm MW}$ and $M_{\rm M31}$. This suggests that the mass of the LG is almost entirely located within the two largest galaxies rather than being dispersed on larger scales or in a background medium. The outskirts of the LG are seemingly rather empty. Combining our measurement for $M_{\rm LG}$ and the mass ratio, we estimate the individual masses of the MW and M31 to be $M_{\rm MW}=(0.8\pm 0.5)\times 10^{12}~{\rm M}_{\odot}$ and $M_{\rm M31}=(1.7\pm 0.3)\times 10^{12}~{\rm M}_{\odot}$, respectively. Our analysis favours M31 being more massive than the MW by a factor of $\sim$2.3, and the uncertainties allow only a small probability (9.8%) that the MW is more massive. This is consistent with other properties such as the maximum rotational velocities, total stellar content, and numbers of globular clusters and dwarf satellites, which all suggest that $M_{\rm M31}/M_{\rm MW}>1$.Comment: 16 pages, 11 figures, 3 tables. Accepted for publication in MNRA

The Hubble Space Telescope Survey of M31 Satellite Galaxies II. The Star Formation Histories of Ultra-Faint Dwarf Galaxies

We present the lifetime star formation histories (SFHs) for six ultra-faint dwarf (UFD; $M_V>-7.0$, $4.9<\log_{10}({M_*(z=0)}/{M_{\odot}})<5.5$) satellite galaxies of M31 based on deep color-magnitude diagrams constructed from Hubble Space Telescope imaging. These are the first SFHs obtained from the oldest main sequence turn-off of UFDs outside the halo of the Milky Way (MW). We find that five UFDs formed at least 50% of their stellar mass by $z=5$ (12.6 Gyr ago), similar to known UFDs around the MW, but that 10-40% of their stellar mass formed at later times. We uncover one remarkable UFD, And XIII, which formed only 10% of its stellar mass by $z=5$, and 75% in a rapid burst at $z\sim2-3$, a result that is robust to choices of underlying stellar model and is consistent with its predominantly red horizontal branch. This ''young'' UFD is the first of its kind and indicates that not all UFDs are necessarily quenched by reionization, which is consistent with predictions from several cosmological simulations of faint dwarf galaxies. SFHs of the combined MW and M31 samples suggest reionization did not homogeneously quench UFDs. We find that the least massive MW UFDs ($M_*(z=5) \lesssim 5\cdot10^4 M_{\odot}$) are likely quenched by reionization, whereas more massive M31 UFDs ($M_*(z=5) \gtrsim 10^5 M_{\odot}$) may only have their star formation suppressed by reionization and quench at a later time. We discuss these findings in the context of the evolution and quenching of UFDs.Comment: 18 pages, 9 figures, 3 appendices, submitted to Ap

Beta Dips in the Gaia Era: Simulation Predictions of the Galactic Velocity Anisotropy Parameter (β) for Stellar Halos

The velocity anisotropy parameter, β, is a measure of the kinematic state of orbits in the stellar halo, which holds promise for constraining the merger history of the Milky Way (MW). We determine global trends for β as a function of radius from three suites of simulations, including accretion-only and cosmological hydrodynamic simulations. We find that the two types of simulations are consistent and predict strong radial anisotropy ($\langle \beta \rangle \sim 0.7$) for Galactocentric radii greater than 10 kpc. Previous observations of β for the MW's stellar halo claim a detection of an isotropic or tangential "dip" at r ~ 20 kpc. Using the N-body+SPH simulations, we investigate the temporal persistence, population origin, and severity of "dips" in β. We find that dips in the in situ stellar halo are long-lived, while dips in the accreted stellar halo are short-lived and tied to the recent accretion of satellite material. We also find that a major merger as early as z ~ 1 can result in a present-day low (isotropic to tangential) value of β over a broad range of radii and angles. While all of these mechanisms are plausible drivers for the β dip observed in the MW, each mechanism in the simulations has a unique metallicity signature associated with it, implying that future spectroscopic surveys could distinguish between them. Since an accurate knowledge of β(r) is required for measuring the mass of the MW halo, we note that significant transient dips in β could cause an overestimate of the halo's mass when using spherical Jeans equation modeling

Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?*

We present the color–magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from highprecision Hubble Space Telescope photometry. We find that the SFH of each galaxy is consistent with them having created at least 80% of the stellar mass by z ∼ 6. For all galaxies, we find quenching times older than 11.5 Gyr ago, compatible with the scenario in which reionization suppresses the star formation of small dark matter halos. However, our analysis also reveals some differences in the SFHs of candidate Magellanic Cloud satellites, i.e., galaxies that are likely satellites of the Large Magellanic Cloud and that entered the Milky Way potential only recently. Indeed, Magellanic satellites show quenching times about 600 Myr more recent with respect to those of other Milky Way satellites, on average, even though the respective timings are still compatible within the errors. This finding is consistent with theoretical models that suggest that satellites’ SFHs may depend on their host environment at early times, although we caution that within the error bars all galaxies in our sample are consistent with being quenched at a single epoch