- no title specified

[1.1] Investigating massive stars and variability at large distances with archival HST observations

Identifying and analyzing the properties of massive stars at a range of metallicities is the first step toward achieving a better understanding of stellar evolution. In this work we analyzed the massive star population of the Virgo Cluster galaxy NGC 4535 and probed variability at 16 Mpc using archival HST WFPC2 observations. Through accurate PSF photometry our study revealed 3672 candidate blue supergiants, 841 candidate yellow supergiants and 370 candidate red supergiants between -11 < Mv <-4 mag among a catalog of 24353 detected sources. We estimated the blue to red supergiant ratio as a decreasing function of galactocentric radius. Using MESA isochrones at solar metallicity, we defined the luminosity function and estimated the star formation history of the galaxy up to 60 Myrs. We conducted a variability search in the V and I filters using three variability indexes: the MAD, the IQR and the inverse von-Neumann ratio. This analysis yielded 120 new variable candidates with absolute magnitudes ranging from Mv = -4 to -11 mag. We classified the variables based on their absolute magnitude and their position on the color-magnitude diagram, using the MESA evolutionary tracks. Among the 120 new candidate variable sources are eight candidate variable red supergiants, three candidate variable yellow supergiants and one candidate luminous blue variable, which we suggest for follow-up observations. We expanded our analysis on the massive star population and variability, to other distant HST Key project galaxies NGC 1326A (16.14 Mpc), NGC 4548 (16.22 Mpc) and NGC 1425 (17.1 Mpc).

For years it was stated that the pre-main sequence (PMS) phases of all massive stars are not observable in the optical as they proceed deeply embedded within the parent molecular cloud. Recent theoretical models however show that some massive stars have not yet arrived at the zero-age main-sequence (ZAMS) at the end of the accretion phase. At that time, they have lost their thick envelopes and thus might be optically visible.

The O-type multiple system Herschel 36 A has always been claimed to be extremely young. In a previous work, using high resolution data from the OWN Survey, we confirmed its triple nature, used a spectral disentangling method to separate the individual components, and determined the orbits with high accuracy. Here we perform quantitative spectral analysis of the disentangled spectra and investigate the evolutionary status of the system.

Our preliminary results show that, if main-sequence evolutionary models are considered, the ages of the stellar components cannot be reconciled with the formation scenario. The discrepancy is solved by assuming that the objects are PMS stars going through the very last contraction to the ZAMS where they will settle in ten to seventy thousand years. Thus, Herschel 36 A is very likely the first O-type star detected just before its arrival to the ZAMS.

[1.3] Analyzing the evolutionary status of iota Ori Aa trough high resolution spectroscopy

Facultad de Ciencias Astronomicas y Geofisicas – Universidad Nacional de La Plata

The spectroscopic binary iota Ori Aa is a system which has been widely studied, composed by an O8 III and a B1 IV star. It was noted by several authors that these two stars cannot be coevals. This consideration, together with its high excentricity, has led some authors to propose that this system could be originated from a close encounter between two binaries in the Trapezium cluster. AE Aur an mu Col may have been also involved in that collision. As a first step to clarify the evolutionary history of these stars we have gathered 267 high resolution spectra from HERMES, FIES and SONG spectrographs. With these data we have computed templates for the spectra of both binary components in iota Ori Aa, and simultaneously measured reliable radial velocities that allow us to propose an improved orbital solution. We present here preliminar chemical abundances and ages for these stars, derived by comparing their spectra with atmosphere models.

To improve the knowledge of the Galactic structure in the second quadrant, we performed a detailed spectro-photometric study of six identified stellar clusters. We used GMOS-S/GEMINI to carry out spectroscopic observations of several early-type candidates, and complemented the information with photometric data from SDSS images. We were able to identify 14 targets as B-type stars, eight of them earlier than B3 and another one as a Be star. We obtained novel parameters for the clusters and found that they are scattered at distances ranging from 1.7 to 8.8 kpc, covering three spiral arms. In particular, we located targets in the “Outer Arm” and probably in the more distant “New Arm”. These results allowed us to obtain a better picture of the Galactic structure.

vi@roe.ac.uk

Jaime Villaseñor, O. H. Ramı́rez-Agudelo, W. D. Taylor, and C. J. Evans

The B-star Binary Characterisation (BBC) Project has obtained 30 epochs of visible spectroscopy for 89 B-type binaries in the 30 Doradus region using FLAMES on the VLT. The goal is to determine the current and intrinsic distribution of orbital parameters to answer questions regarding the influence of binarity on the evolution of these objects, and its impact on the nature of core-collapse supernovae and gravitational wave sources. This poster presents our fitting methods used to measure radial velocities and our determinations of orbital periods. Our first results for the complete sample are discussed together with the next steps for this project.

Nearly a quarter of all massive stars will merge during their lifetimes. The contact phase of massive binaries, preceding coalescence, is poorly understood due to a lack of observational constraints: only 7 O-type overcontact binaries are currently known. Stars in these systems may suffer from enhanced mixing due to rotation and tidal effects. Such enhanced mixing can induce chemically homogeneous evolution (CHE), a fundamentally different evolutionary channel where the 2 stars remain compact, preventing them from merging. Such a channel has recently been proposed as a viable way to create close and massive blackhole binaries that can explain the GW150914 gravitational wave event. However, the viability of this GW channel depends on the efficiency of the poorly-understood mixing processes. We use VLT/optical and HST/UV data of an LMC overcontact binary that shows evidence of enhanced mixing: VFTS 352 (O4.5V+O5.5V; P = 1.12d). We also use HERMES/optical and VLT/optical data of other known massive overcontact binaries. We present new observational constraints on the physical parameters and surface abundances (He, C, N, O, Si), compare them with binary evolution models, and discuss our results in the context of CHE. Additionally, we briefly discuss a new 2D surface patch modeling method developed for the analysis of these overcontact systems. We find strong spectroscopic evidence for enhanced mixing, however our findings also indicate the observationally determined surface abundances for VFTS 352 are incompatible with current mixing theories.

Aluminium-26, a radioactive isotope with a half life of 0.72 Myr, was present in the early Solar System, as inferred from Mg-26 excess in meteorites, see e.g. Jacobsen, B. et al. 2008. It is also detected in the Galaxy via gamma-ray observations from COMPTEL and INTEGRAL, see R. Diehl 2013. While it is known that Al-26 is produced in stars, many uncertainties are left related to the production sites and the nuclear physics input. Past research has focused mostly on yields of Al-26 from massive single stars, both rotating and non-rotating, including their winds and supernova explosions, see Limongi, M. and Chieffi, A., 2006 & 2018, Chieffi, A. and Limongi, M., 2013, Ekström et al. 2012, , Woosley, S. E., and Heger, A., 2007. Here I will present the first results of my research that will focus on the yields from massive star winds, primarily Wolf-Rayet stars >30Msun, both single and in binary systems, and on the yields from non-conservative mass transfer in binary systems with primary masses >15Msun. The final goal is to discover the impact of massive binary stars on the galactic abundance of Al-26 and on the origin of the Al-26 in the early Solar System.

Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata

Galactic B[e] supergiants (B[e]sgs) are luminous and massive post-main sequence stars that show permitted and forbidden emission lines and large infrared emission. Plausible explanations for the B[e] phenomenon among B-type supergiants are related with either rapid stellar rotation or gravitational interactions with a companion. Our goal is to undertake a new study of the binary system HD 327083 in order to better constrain the orbital parameters and physical properties of its circumstellar envelope (size, density, temperature and dynamics). A thorough knowledge of the nature of the binary system is a fundamental key to understand the origin and evolution of stars showing the B[e] phenomenon and to discuss the origin of the molecular and dusty disks

Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata

Analytical expressions to obtain wind parameters and velocity profiles have major advantages over numerical hydrodynamical calculations. Using the Lambert W-function we were able to obtain a velocity profile closed-form solution in terms of the m-CAK line-force parameters. Moreover, a prescription for the mass-loss rate for massive stars was also derived. Based on self-consistent calculations on the line-force parameters and analytical expressions for different line-driven wind regimes, we compute synthetic line profiles.

[2.5] A new method to find multiperiodic variations. Applications to B supergiants

B supergiant stars (BSGs) occur in two different phases of evolution: in the pre- and post-red supergiant (RSG), and they share their loci in the HR diagram. These stars exhibit multiperiodic variations of light and line profiles that could be related to pulsations. From theoretical calculations, Saio et al. showed that the pulsation properties of BSGs change drastically between these two stages. In principle, a detailed analysis of pulsation periods could be used to distinguish stars from both groups. To this aim, we develop a new method to find periodicity in a signal, based on a simplification of the Voronoi cells and Delaunay triangulation paradigms. We present here the comparison between its performance against other methods, and we show preliminary results on some BSGs' light curves.

We are developing a new post-processing code for stellar nucleosynthesis calculations. Here we present our preliminary version and first tests.

[3.1] Suppressed winds: a new view on stellar feedback in young stellar clusters

A traditional model for mechanical feedback from massive star clusters suggests that stellar winds of individual massive stars rapidly merge and form powerful outflows which clean stellar clusters from the leftover gas. These outflows play a crucial role in galaxy, interstellar and intergalactic medium evolution. Indeed, optical observations were failed to detect a significant amount of gas in a number of present day young massive clusters that agrees with this paradigm and seems to confirm that young stellar clusters expel natal gas at the age of a few Myr. However, recent IR and ALMA radio observations with high spatial resolution revealed clusters, which still remain deeply embedded into their natal molecular clouds and therefore are highly obscured for observations in the optical line regime. Here I discuss an alternative to the traditional paradigm model for the interplay among massive stars and primordial gas in star-forming clouds. Conditions, which are required to suppress the negative stellar feedback, and threshold lines, which separate the gas expulsion and the gas retention regimes in the star cluster size vs the natal molecular cloud mass parameter space, are presented. These are compared with parameters of star-forming clouds at the present epoch and at the epoch of globular clusters formation.

To explain the nature of the anomalously high reddening (Av≃ 10 mag) towards one of the most luminous stars in the Galaxy – Cyg OB2 #12 (B5 Ia-0), also known as MT304, we carried out spectro-photometric observations of 24 stars located in its vicinity. We included five new B-stars among the members of Cygnus OB2, and for five more photometrically selected stars we spectroscopically confirmed their membership. We constructed the map of interstellar extinction within 2.5 arcmin radius and found that interstellar extinction increases towards MT304. According to our results the most reddened OB-stars in the association after MT304 are J203240.35+411420.1 and J203239.90+411436.2, located about 15 arcsec away from it. Interstellar extinction towards these stars is about 9 mag. The increase of reddening towards MT304 suggests that the reddening excess may be caused by the circumstellar shell ejected by the star during its evolution. We also report the detection and measurements of the orbit of a second component of MT304, and discovery of an even fainter third component, based on data of speckle interferometric observations taken with the Russian 6-m telescope. We discuss our results in the context of recent Gaia DR2 data.

[3.3] An analysis of the energetics involved in the HI supershells possible related to massive stars

The Milky Way, when viewed in the neutral hydrogen (HI) line emission, presents large structures called galactic supershells (GSs). The origin of these structures is still a subject of debate. The most common scenario invoked is the combined action of strong winds from massive stars and their subsequent explosion as supernova. The aim of this work is to determine the origin of 490 GSs that belong to the "Catalog of HI supershell candidates in the outer part of the Galaxy" of Suad et al. 2014 (A&A 564A 116S). To know the physical processes that took place to create these expanding structures, it is necessary to determine their kinetic energies. To obtain all the GSs masses, we have developed and used an automatic algorithm. We found that the kinetic energies are between 0.2 to 67.4x10^{50} ergs and that the 95% of the GSs have energies lower than 4x10^{50} erg, which, for a stellar origin, implies that a wind energy greater than 2x10^{51} erg is required. This amount of energy can be easily supplied by OB associations. According to the interval of energies obtained, a stellar origin is possible for most of the GSs. However, more than one star is needed and, in most of the cases, given their high ages, more than one stellar generation, including several SN explosions.

[3.4] Analysis of the radio continuum emission in the vicinity of faint galactic Wolf-Rayet stars

Massive stars play a fundamental role in the chemical and dynamical evolution of the interstellar medium, since they emit a large number of highly energetic photons that ionize the surrounding gas and raise the temperature of the dust. They also dominate the dynamics of the gas, due to their powerful winds. During their evolution, the stars go through different phases, depending on their initial mass. In particular, if they are born with more than 25 solar masses, they eventually become a Wolf-Rayet type star, while their winds increase in an order of magnitude. These stronger winds interact with the interstellar medium, previously modified during the main-sequence stage, producing new peculiar disturbances. In this work, we present a first morphological analysis of the interstellar medium in the vicinity of 71 Wolf-Rayet stars recently identified in the infrared. In this first instance, we use images of the 1420 MHz radio continuum emission obtained from the VLA Galactic Plane Survey and the Southern Galactic Plane Survey. From the inspection of these images, we analyze the effects that different factors, such as the density of the medium, the stellar proper motion, and the evolutionary stage of the star, produce on the formation and evolution of these structures. Thus, a tailored morphological study provides valuable information about the stellar winds and the nature of the surrounding gas. In turn, given that these stars end their lives exploding as a supernova, this analysis also provides observational hints about the initial conditions where the explosions take place.

The region of the G316.8-0.1 radio source host also the IRAS 14416-5937 source and the embedded clusters DBS 89-90-91. We studied this region, identified as a star forming region, using the combination of data at different spectral ranges. They include photometric infrared (2MASS, VVV, Spitzer, Herschel) and radio (SGPS, PMN) surveys. These data were complemented with already known information for some particular objects in the area. With this information, we could carried out an analysis of the stellar populations and structures of the interstellar medium (ISM) in this direction assessing the possible relation between them. We obtained preliminary values of the main features of the clusters as their stellar densities, distances, reddenings and sizes. Additionally, we could identify some YSO candidates. Regarding the ISM, we could estimate the electronic density, excitation parameter and mass of the HII Region.

WR16 is one of the Wolf-Rayet stars exhibiting a very conspicuous round optical nebula, composed of mass ejected in the RSG or LBV phase of the star, and an outer arc-like feature. In this work we present a study of the molecular gas related to this nebula using observations carried out with the ASTE telescope. We observed the CO(3-2) and HCO+(4-3) lines in a region of 12' x 12', centered on the star. From the analysis of these data we found and characterize seven clumps located around the nebula. The nebula around WR16 is also detected in the infrared, in the 22 and 70 microns bands, as revealed by the WISE and Herschel images. A study of the dust properties is also presented.

[4.1] Modeling of interaction between supernova ejecta and aspherical circumstellar material

Massive stars, the progenitors of core-collapse supernovae~(SNe), may lose their mass via outflowing circumstellar disks. We study the hydrodynamics of collisions between expanding SN ejecta and asymmetric circumstellar material (CSM). For time-dependent hydrodynamic modeling we use our own grid-based Eulerian multidimensional unsplit hydrodynamic code that is highly efficient for calculation of shocks and physical flows with large discontinuities. We calculate the evolution of the SN-CSM system and the rate of aspherical deceleration as well as the behavior of density, pressure, expansion velocity and temperature structure in the interaction zone under various geometrical configurations and various initial densities of CSM. The interaction of SN ejecta and CSM leads to aspherical expansion even for medium disk mass-loss rates of 10**(-9) solar masses per year. Study of SN light curves powered by an energy excess of such interaction will lead to a better understanding of CSM and SN progenitors density distribution, and will improve our understanding of final evolutionary stages of massive stars.

The explosion mechanisms that lead to core collapse supernovae are still uncertain. One way to constrain theoretical models is to explore the 3 dimensional geometry of SNe at early days, and spectropolarimetry offers a direct tool to probe the shape of unresolved supernovae only a few days after explosion. We will present 7 epochs of spectropolarimetry for the type IIb SN 2011hs, ranging from -2 days to +40 days with respect to V-band maximum. Our analysis and interpretation of the data of SN 2011hs will be included in the broader context of other IIb SNe with spectropolarimetric observations, for which we also offer an updated analysis through the use of our toy model.

P Cygni, the hypergiant which has undergone great eruptions in 17-th century and gradually reddens until now probably will have the next eruption or even supernova explosion in near future. It seems that this statement has rather realistic basis according to historical light-curve of P Cygni and long-term BV photometric observations of the star obtained in Abastumani Observatory, Georgia, during 1951-1983. We are reporting the first results of modeling of the stellar atmosphere using The Potsdam Wolf-Rayet Model Atmosphere Code (PoWR). We used the above mentioned and new photometric observations together with the spectral data of different space and ground-based telescopes held during the last decades.

The advanced stages of high-mass stars are characterized by episodic mass loss shed during phases of instability. Key for assigning these stars a proper evolutionary state is to assess the composition and geometry of their ejecta alongside the stellar properties. We selected five hot LBV candidates in M33 to refine their classification, investigate their circumstellar environments and explore their evolutionary properties. Being accessible targets in the near-infrared, we conducted medium-resolution spectroscopy with GNIRS/GEMINI in the K−band to investigate their molecular circumstellar environments. Two stars were found to display CO emission, which was modeled to emerge from a circumstellar or circumbinary Keplerian disk/ring. The identification of the carbon isotope 13C and, for one of the two stars, a significantly low 12CO/13CO ratio, implies an evolved stellar state. As both CO emission stars are highly luminous and hence do not undergo a red supergiant phase, we suggest that stripping processes and equatorial high-density ejecta due to fast rotation are responsible for the enrichment of the stellar surface with processed material from the core. A candidate B[e]SG displays an absorption CO profile, which may be attributed to a jet, stellar pulsations, or a cool companion. The featureless infrared spectra of two stars suggest a low-density gas shell or dissipation of the molecule due to the ionizing temperature of the star. We highlight the importance of the infrared data to resolve the evolutionary status of massive stars in transition and thus, to constrain the physics of the diverse pre-supernova stellar states.

[4.5] Polarized lines and the progenitors of core-collapse supernovae

Hoffman Jennifer L.

jennifer.hoffman@du.edu

Jennifer L. Hoffman (U. Denver), Leah N. Huk (ORNL), June Churchill (U. Denver), Sophia DeKlotz (U. Denver), Kevin Cooper (U. Denver), G. Grant Williams (MMT Observatory), and the Supernova Spectropolarimetry Project

Polarized emission and absorption lines in core-collapse supernovae (CCSNe) trace detailed structures in the ejecta and surrounding circumstellar medium (CSM) that contain clues to the end stages of their progenitors' evolution. Extracting this geometrical information, however, requires careful computational modeling that takes into account the 3-D distribution of the ejecta and CSM and the potentially polarizing nature of line scattering. We present the results of such modeling for several CCSNe with multi-epoch polarization observations obtained by the Supernova Spectropolarimetry Project with the SPOL spectropolarimeter. In the cases of "interacting supernovae," time-variable line polarization can constrain the shape and density of the surrounding CSM, thereby yielding valuable information about the progenitor's late-stage mass loss episodes. In stripped-envelope supernovae, it provides new, quantitative evidence for the asymmetric nature of the explosions and the possible role of binary companions in shaping the supernova ejecta.

[4.6] Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the LBV R71

Luminous blue variables (LBVs) are evolved massive stars that exhibit instabilities that are not yet understood. Stars can lose several solar masses during this evolutionary phase. The LBV phenomenon is thus critical to our understanding of the evolution of the most massive stars. The LBV R71 in the Large Magellanic Cloud is presently undergoing an S Doradus outburst, which started in 2005. We determine the fundamental stellar parameters of R71 during its quiescence phase with the radiative transfer code CMFGEN. During its current S Doradus outburst, R71 exhibits similar irregular variations as RV Tau variables. The occurrence of double absorption lines with an apparent regular cycle may be due to shocks within the atmosphere and period doubling may explain the factor of two in the lengths of the photometric and spectroscopic cycles.

How the energy released during a Core Collapse Supernova (SN) is coupled to the outer envelopes of the exploding star is poorly understood. Numerical simulations suggest the central engine should be aspherical and observational evidence exists demonstrating this. The most convincing evidence for the asymmetry of supernovae comes from spectropolarimetry. The polarisation of supernovae depends on a number of factors, such as the geometry and composition of the ejecta. In order to fully understand the dependency of the polarimetric data on these factors, detailed radiative transfer simulations must be done. Here, a Monte Carlo radiative transfer code that has been developed in order to tackle these problems will be presented. This code propagates virtual photons through a prescribed atmosphere, with polarisation induced through electron scattering. The code is fully 3D, allowing complex geometries to be investigated and providing a simple way of simulating aspherical SNe explosions. Simulations have been done in order to investigate the spectropolarimetry observed in SN impostors and Type IIn SNe, with a simple treatment of the H-alpha line included in the models.

[4.8] Broadband emission modeling of supernova remnants as a probe of late-time mass loss history of massive stars

The understanding of the late-time mass loss of massive stars is essential not only for elucidating their mysterious evolution history but also for linking observational properties of core-collapse supernovae and their progenitor origins. In some cases, substantial evidences of enhanced or even extreme mass loss prior to core-collapse have been found from SNe of various types, but its mechanism still remains a puzzle. On the other hand, the circumstellar medium (CSM) modified by pre-SN episodic mass loss is expected to interact with the SNR blast wave and produce strong electromagnetic signals, which can serve as a powerful probe of the CSM profile and hence the mass loss history. We will present results from our broadband emission models of SNR-CSM interaction for cases of enhanced pre-SN mass loss using a hydrodynamic simulation coupled with nonlinear diffusive shock acceleration of relativistic particles. Future multi-wavelength data from young core-collapse SNRs such as high-sensitivity VHE gamma-ray observations and micro-calorimetric X-ray spectroscopy will provide a stringent test to our models. This will pave a new path to connect the different stages of the massive star evolution from progenitors to SNRs.

The presence of massive neutrinos and the mixing between active and sterile flavors, affects the rates of nuclear reactions in which they participate, therefore a reformulation of the weak decay rates in terms of neutrino oscillation parameters and couplings is needed to explain various astrophysical processes, such nuclear reaction chains in stellar media. In the context of core-collapse supernovae, the process responsible for the production of nuclei heavier than iron is the rapid neutron-capture process, or r-process for short. The two main mechanisms of the r-process are the consecutive captures of neutrons followed by beta decays. In this work we present the calculation of the beta decay rates for each nuclei involved as a function of the neutrino mixing parameters. And its effects upon the final abundances which this elements are ejected to the interstellar medium.

[4.10] Effect of circumstellar material on the early light curve of hydrogen-rich supernovae

We present an analysis of the effect of circumstellar material (CSM), possibly ejected by the progenitor star years before the explosion, on the early light curve (LC) of hydrogen-rich supernovae (SNe II). The analysis is performed using a one-dimensional hydrodynamical code (Bersten et al. 2011) that simulates stellar explosions and calculates LCs under different physical conditions. The properties of the CSM were characterized by means of three parameters: the radial extent, the mass-loss rate, and the density slope. The effect of these parameters on the LC morphology are analyzed. A test case is presented for the very well-observed Type II SN 2004et. For this event we show that some CSM is necessary to obtain a good agreement with the early observations. The required CSM properties imply a high mass-loss rate of ~0.28 M⊙/yr. Finally, we analyzed relations between some observable parameters of the bolometric LCs of SN II and properties of their progenitors, for models with and without CSM.

[5.1] A connection between Fast Radio Bursts and massive stars suggested by the statistical properties of FRB observables

Fast Radio Bursts (FRBs) are transient events observed in ~ 1 GHz radio bands with typical durations of several milliseconds. Their large dispersion measures (DMs), which indicate the column density of free electrons along the sightlines, suggest that they are extragalactic objects. If the FRB DMs arise from the intergalactic medium (IGM), the DMs indicates that FRBs originate at cosmological distances at redshifts ~ 1. However, it is also possible that FRBs are in the local universe and their large DM arise from their circum-burst medium. In this study, we analytically compute the expected distributions of DMs, flux densities, and fluences of FRBs considering both cases that FRBs are at cosmological distances and in the local universe. Comparing the predictions with the observations, we show that the observed properties of FRBs suggest that they originate at cosmological distances and the cosmic FRB rate density increases with redshift resembling cosmic star formation history.

[5.2] Correlational study between model variables and observable quantities of magnetar-powered H-rich supernovae

It has not been possible, yet, to identify the presence of a magnetar in a supernova explosion (SN). We know only pieces of a challenging problem that poses ahead extremely important questions. If a magnetar with a sufficiently high rotation speed is actually present in a given SN, it would contribute with an additional source of energy. That power may overcome the energy released by otherwise usual mechanisms, so a magnetar could give birth to a superluminous SN. A grid of hydrodynamic models (with a simple treatment for radiative processes) has been recently computed for a hydrogen-rich progenitor of M_ZAMS = 15 Msun. The corresponding light curves (LCs) show indirect evidence of the properties of the magnetar. By means of a correlational analysis we investigate the existence of a correspondence between the variables used to define the models (initial rotation energy and spin-down timescale) and observable quantities obtained from the LCs. This study might help to define search strategies in order to obtain evidence of the magnetar engine working into SNe with good photometric data. Herein we present some preliminary results.

[6.1] Extinction laws towards supernova host galaxies with integral field spectroscopy

ESO/Universidad de Chile than the standard Rv = 3.1, with unusual low values inferred from Type Ia supernova (SN Ia) photometric observations, revealing peculiar dust properties of the interstellar medium (ISM). U

Accurate measurements of the extinction along the line-of-sight of supernovae are essential for determining distances in observational cosmology. Extinction curves, commonly parametrized by the total-to-selective extinction ratio Rv, have been found to be steeper than the standard Rv = 3.1, with unusual low values inferred from Type Ia supernova (SN Ia) photometric observations, revealing peculiar dust properties of the interstellar medium (ISM). U

sing spectroscopic data from All-weather MUse Supernova Integral field Nearby Galaxies (AMUSING) survey, we estimate stellar population extinction by fitting population synthesis models to observations. To minimize the degeneracy between extinction, age and metalsing spectroscopic data from All-weather MUse Supernova Integral field Nearby Galaxies (AMUSING) survey, we estimate stellar population extinction by fitting population synthesis models to observations. To minimize the degeneracy between extinction, age and metallicity when measuring Rv, we combine UV- optical photometry with Integral Field Unit (IFU) spectra with an all- encompassing data homogenization technique. The possibility to treat Rv as independent parameter is currently being implemented in the SED fitting software we ar corresponding to ∼ 135 pc).

[7.1] Cosmology using long gamma ray bursts: statistical analysis of errors in the calibrated data

In this paper we used ∆ statistic and Kolmogrov Smirniov test to investigate non-Gaussian features in the High-z cosmological data. We apply these statistics on the set of calibrated Long Gamma Ray Burst(GRB) and their combination with Supernovae type Ia (Union2). Our statistical analysis show that both the data sets shows non-Gaussian nature of errors with weak but consistent direction dependence.

[7.2] Correlation between GRB peak-energy and SN luminosity from the homogenization of GRB-associated supernova observations

Long gamma-ray bursts (GRBs) have been found in association with core-collapse supernovae (SNe) since the emblematic case of the GRB 980425/SN 1998bw. They are thought to be the final fate of some massive stars (larger than about 15 solar masses). The GRB emission can be detected up to very high redshifts (z~9) and their SN counterpart has been observed up to redshift of ~1. Correlations could be useful, e.g., in determining extragalactic distances and intrinsic luminosities, if it was not for the large diversity of GRB-SN observations. Future all-sky surveys, e.g. LSST, will find hundreds of orphan GRB afterglows. It proves necessary to develop a robust methodology to standardize the luminosities of the associated SNe. Here we present the first steps towards reliable distance-indicator methods. With a sample of 30 GRB-SNe from the literature, we selected those having at least photometric observations in two filter bands. We develop a methodology to bypass the K correction and derive an accurate rest-frame brightness of the SN counterpart. Taking into account parameters from the main GRB emission and from the SN, we explore the GRB-SN parameter space in search for correlations. We found that using the peak spectral energy of the GRB main emission proves promising to standardize the SN luminosities. While SNe Ia and II deliver distances as precise as 7% and 10%, respectively, we demonstrate that GRB-SNe can determine distances with 13% precision. These results unfold new opportunities to exploit GRB-SNe to probe the cosmic expansion of the Universe.