We present detailed investigation of a specific i-band light-curve feature in Type Ia supernovae (SNe Ia) using the rapid cadence and high signal-to-noise ratio light curves obtained by the Carnegie Supernova Project. The feature is present in most SNe Ia and emerges a few days after the i-band maximum. It is an abrupt change in curvature in the light curve over a few days and appears as a flattening in mild cases and a strong downward concave shape, or a 'kink', in the most extreme cases. We computed the second derivatives of Gaussian Process interpolations to study 54 rapid-cadence light curves. From the second derivatives we measure: (1) the timing of the feature in days relative to i-band maximum; tdm(2)(i) and (2) the strength and direction of the concavity in mag d(-2); dm(2)(i). 76 per cent of the SNe Ia show a negative dm(2)(i), representing a downward concavity - either a mild flattening or a strong 'kink'. The tdm(2)(i) parameter is shown to correlate with the colour-stretch parameter s(BV), a SN Ia primary parameter. The dm(2)(i) parameter shows no correlation with s(BV) and therefore provides independent information. It is also largely independent of the spectroscopic and environmental properties. Dividing the sample based on the strength of the light-curve feature as measured by dm(2)(i), SNe Ia with strong features have a Hubble diagram dispersion of 0.107 mag, 0.075 mag smaller than the group with weak features. Although larger samples should be obtained to test this result, it potentially offers a new method for improving SN Ia distance determinations without shifting to more costly near-infrared or spectroscopic observations.

Type II supernovae (SNe II) show great photometric and spectroscopic diversity which is attributed to the varied physical characteristics of their progenitor and explosion properties. In this study, the third of a series of papers where we analyse a large sample of SNe II observed by the Carnegie Supernova Project-I, we present correlations between their observed and physical properties. Our analysis shows that explosion energy is the physical property that correlates with the highest number of parameters. We recover previously suggested relationships between the hydrogen-rich envelope mass and the plateau duration, and find that more luminous SNe II with higher expansion velocities, faster declining light curves, and higher Ni-56 masses are consistent with higher energy explosions. In addition, faster declining SNe II (usually called SNe IIL) are also compatible with more concentrated Ni-56 in the inner regions of the ejecta. Positive trends are found between the initial mass, explosion energy, and Ni-56 mass. While the explosion energy spans the full range explored with our models, the initial mass generally arises from a relatively narrow range. Observable properties were measured from our grid of bolometric LC and photospheric velocity models to determine the effect of each physical parameter on the observed SN II diversity. We argue that explosion energy is the physical parameter causing the greatest impact on SN II diversity, that is, assuming the non-rotating solar-metallicity single-star evolution as in the models used in this study. The inclusion of pre-SN models assuming higher mass loss produces a significant increase in the strength of some correlations, particularly those between the progenitor hydrogen-rich envelope mass and the plateau and optically thick phase durations. These differences clearly show the impact of having different treatments of stellar evolution, implying that changes in the assumption of standard single-star evolution are necessary for a complete understanding of SN II diversity.

The present study is the first of a series of three papers where we characterise the type II supernovae (SNe II) from the Carnegie Supernova Project-I to understand their diversity in terms of progenitor and explosion properties. In this first paper, we present bolometric light curves of 74 SNe IL We outline our methodology to calculate the bolometric luminosity, which consists of the integration of the observed fluxes in numerous photometric bands (uBgVriY JH) and black-body (BB) extrapolations to account for the unobserved flux at shorter and longer wavelengths. BB fits were performed using all available broadband data except when line blanketing effects appeared. Photometric bands bluer than r that are affected by line blanketing were removed from the fit, which makes near-infrared (NIR) observations highly important to estimate reliable BB extrapolations to the infrared. BB fits without NIR data produce notably different bolometric light curves, and therefore different estimates of SN II progenitor and explosion properties when data are modelled. We present two methods to address the absence of NIR observations: (a) colour-colour relationships from which NIR magnitudes can be estimated using optical colours, and (b) new prescriptions for bolometric corrections as a function of observed SN II colours. Using our 74 SN II bolometric light curves, we provide a full characterisation of their properties based on several observed parameters. We measured magnitudes at different epochs, as well as durations and decline rates of different phases of the evolution. An analysis of the light-curve parameter distributions was performed, finding a wide range and a continuous sequence of observed parameters which is consistent with previous analyses using optical light curves.

Linking supernovae to their progenitors is a powerful method for furthering our understanding of the physical origin of their observed differences while at the same time testing stellar evolution theory. In this second study of a series of three papers where we characterise type II supernovae (SNe II) to understand their diversity, we derive progenitor properties (initial and ejecta masses and radius), explosion energy, and Ni-56 mass and its degree of mixing within the ejecta for a large sample of SNe IL This dataset was obtained by the Carnegie Supernova Project-I and is characterised by a high cadence of SNe II optical and near-infrared light curves and optical spectra that were homogeneously observed and processed. A large grid of hydrodynamical models and a fitting procedure based on Markov chain Monte Carlo methods were used to fit the bolometric light curve and the evolution of the photospheric velocity of 53 SNe II. We infer ejecta masses of between 7.9 and 14.8 M-circle dot, explosion energies between 0.15 and 1.40 foe, and Ni-56 masses between 0.006 and 0.069 M-circle dot. We define a subset of 24 SNe (the 'gold sample') with well-sampled bolometric light curves and expansion velocities for which we consider the results more robust. Most SNe II in the gold sample (similar to 88%) are found with ejecta masses in the range of similar to 8-10 M-circle dot, coming from low zero-age main-sequence masses (9-12 M-circle dot). The modelling of the initial-mass distribution of the gold sample gives an upper mass limit of 21.3(-0.4)(+3.8)M(circle dot) and a much steeper distribution than that for a Salpeter massive-star initial mass function (IMF). This IMF incompatibility is due to the large number of low-mass progenitors found - when assuming standard stellar evolution. This may imply that high-mass progenitors lose more mass during their lives than predicted. However, a deeper analysis of all stellar evolution assumptions is required to test this hypothesis.

We present 75 near-infrared (NIR; 0.8-2.5 mu m) spectra of 34 stripped-envelope core-collapse supernovae (SESNe) obtained by the Carnegie Supernova Project-II (CSP-II), encompassing optical spectroscopic Types IIb, Ib, Ic, and Ic-BL. The spectra range in phase from pre-maximum to 80 days past maximum. This unique data set constitutes the largest NIR spectroscopic sample of SESNe to date. NIR spectroscopy provides observables with additional information that is not available in the optical. Specifically, the NIR contains the strong lines of He i and allows a more detailed look at whether Type Ic supernovae are completely stripped of their outer He layer. The NIR spectra of SESNe have broad similarities, but closer examination through statistical means reveals a strong dichotomy between NIR "He-rich" and "He-poor" SNe. These NIR subgroups correspond almost perfectly to the optical IIb/Ib and Ic/Ic-BL types, respectively. The largest difference between the two groups is observed in the 2 mu m region, near the He i lambda 2.0581 mu m line. The division between the two groups is not an arbitrary one along a continuous sequence. Early spectra of He-rich SESNe show much stronger He i lambda 2.0581 mu m absorption compared to the He-poor group, but with a wide range of profile shapes. The same line also provides evidence for trace amounts of He in half of our SNe in the He-poor group.

Since the discovery of the accelerating expansion of the Universe more than two decades ago, Type Ia Supernovae (SNe Ia) have been extensively used as standardisable candles in the optical. However, SNe Ia have shown to be more homogeneous in the near-infrared (NIR), where the effect of dust extinction is also attenuated. In this work, we explore the possibility of using a low number of NIR observations for accurate distance estimations, given the homogeneity at these wavelengths. We found that one epoch in J and/or H band, plus good gr-band coverage, gives an accurate estimation of peak magnitudes in the J (J(max)) and H (H-max) bands. The use of a single NIR epoch only introduces an additional scatter of similar to 0.05 mag for epochs around the time of B-band peak magnitude (T-max). We also tested the effect of optical cadence and signal-to-noise ratio (S/N) in the estimation of T-max and its uncertainty propagation to the NIR peak magnitudes. Both cadence and S/N have a similar contribution, where we constrained the introduced scatter of each to < 0.02 mag in J(max) and < 0.01 in H-max. However, these effects are expected to be negligible, provided the data quality is comparable to that obtained for observations of nearby SNe (z less than or similar to 0.1). The effect of S/N in the NIR was tested as well. For SNe Ia at 0.08 < z less than or similar to 0.1, NIR observations with better S/N than that found in the CSP sample is necessary to constrain the introduced scatter to a minimum (less than or similar to 0.05 mag). These results provide confidence for our FLOWS project that is aimed at using SNe Ia with public ZTF optical light curves and few NIR epochs to map out the peculiar velocity field of the local Universe. This will allow us to determine the distribution of dark matter in our own supercluster, Laniakea, and to test the standard cosmological model by measuring the growth rate of structures, parameterised by fD, and the Hubble-Lemaitre constant, H-0.

The Magellanic Clouds are a local laboratory for understanding the evolution and properties of dwarf irregular galaxies. To reveal the extended structure and interaction history of the Magellanic Clouds we have undertaken a large-scale photometric and spectroscopic study of their stellar periphery (the MAgellanic Periphery Survey, MAPS). We present first MAPS results for the Small Magellanic Cloud (SMC): Washington M, T-2 + DDO51 photometry reveals metal-poor red giant branch stars in the SMC that extend to large radii (similar to 11 kpc), are distributed nearly azimuthally symmetrically (ellipticity = 0.1), and are well fitted by an exponential profile (out to R approximate to 7 degrees.5). An similar to 6 Gyr old, [Fe/H] approximate to - 1.3 main-sequence turnoff is also evident to at least R = 7 degrees.3, and as far as 8 degrees.4 in some directions. We find evidence for a "break" population beyond similar to 8 radial scale lengths having a very shallow radial density profile that could be either a bound stellar halo or a population of extratidal stars. The distribution of the intermediate stellar component (3 degrees less than or similar to R less than or similar to 7 degrees.5) contrasts with that of the inner stellar component (R less than or similar to 3 degrees), which is both more elliptical (epsilon approximate to 0.3) and offset from the center of the intermediate component by 0 degrees.59, although both components share a similar radial exponential scale length. This offset is likely due to a perspective effect because stars on the eastern side of the SMC are closer on average than stars on the western side. This mapping of its outer stellar structures indicates that the SMC is more complex than previously thought.

A superior mutual event of the Kuiper Belt binary system (79360) Sila-Nunam was observed over 15.47 h on UT 7/8 February 2013 by a coordinated effort at four different telescope facilities; it started similar to 1.5 h earlier than anticipated, the duration was similar to 9.5 h (about 10% longer than predicted), and was slightly less deep than predicted. It is the first full event observed for a comparably sized binary Kuiper Belt object. We provide predictions for future events refined by this and other partial mutual event observations obtained since the mutual event season began. (C) 2013 Elsevier Inc. All rights reserved.

Dark Skies, Bright Kids! (DSBK) is an outreach organization that seeks to enhance elementary-level science literacy and encourage inquiry through fun, hands-on activities. DSBK was formed by, and is operated through, volunteer efforts from professional scientists at all career stages, e.g., from first-year undergraduate students to tenured professors. Although DSBK has amassed over 14,000 contact hours since 2009, there has been no formal evaluation of the programs impacts. Over the past year, DSBK introduced a large-scale, student-led internal assessments program with the systematic evaluation of student workbooks, volunteer surveys, and observations. While the data indicated broad-scale success for the program for both of its goals, it also revealed the organizational and educational practices that not only maximized student achievement, but also created the largest overall volunteer satisfaction with their time commitment. Here we describe DSBK in detail, summarize the student-led implementation of the assessments program, discuss how the results of the assessments have positively impacted our operations, and generalize these results for other scientist-led outreach efforts.

We spectroscopically identify a sample of carbon stars in the satellites and halo of M31 using moderate-resolution optical spectroscopy from the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We present the photometric properties of our sample of 41 stars, including their brightness with respect to the tip of the red giant branch (TRGB) and their distributions in various color-color spaces. This analysis reveals a bluer population of carbon stars fainter than the TRGB and a redder population of carbon stars brighter than the TRGB. We then apply principal component analysis to determine the sample's eigenspectra and eigencoefficients. Correlating the eigencoefficients with various observable properties reveals the spectral features that trace effective temperature and metallicity. Putting the spectroscopic and photometric information together, we find the carbon stars in the satellites and halo of M31 to be minimally impacted by dust and internal dynamics. We also find that while there is evidence to suggest that the sub-TRGB stars are extrinsic in origin, it is also possible that they are are particularly faint members of the asymptotic giant branch.