Gravitational-wave (GW) observations are revealing the population of compact objects from a new angle. Yet their stellar progenitors remain uncertain because few observational clues on their progenitors exist. Theoretical models typically assume that the progenitor evolution can be approximated with single-star models. We explore how binary evolution affects the pre-supernova (SN) structure of stars, and the resulting distribution of compact object remnants. We focus on the differences in the core properties of single stars and of donor stars that transfer their outer layers in binary systems and become binary-stripped. We show that the final structures of binary-stripped stars that lose their outer layers before the end of core helium burning are systematically different compared to single stars. As a result, we find that binary-stripped stars tend to explode more easily than single stars and preferentially produce neutron stars and fewer black holes, with consequences for GW progenitors.

We present low-frequency (0.40 – 1.25 GHz) radio observations and modeling of a Fast Blue Optical Transient (FBOT), AT2018cow [Nayana & Chandra(2021)]. Our data are best modeled as an inhomogeneous synchrotron emitting region expanding into an ionized circumstellar medium. We estimate the mass-loss rate of the progenitor star and shock parameters at multiple epochs post-explosion and find that the progenitor has gone through an enhanced phase of mass-loss close to its end-of-life.

We compare pre-supernova observations with synthetic photometry from stellar evolution models to infer the progenitor properties of the seven known progenitors of Type Ib and IIb supernovae. Our results are roughly consistent with a hydrogen mass threshold of for a Type II appearance.

The jittering jets explosion mechanism of core collapse supernovae proposes that stochastic convective motion, amplified by instabilities, results in intermittent accretion disk that launches jittering jets that explode the star. We conduct one-dimensional simulations of a wide range of stellar masses and show that the convective motion in the pre-collapse stellar core, when scaled to corresponding three-dimensional simulations, supply sufficient angular momentum fluctuation to form the intermittent accretion disk the launches the jittering jets. The resulting neutron star masses are consistent with observations.

We present photometric and spectroscopic studies of two type IIP SNe (SN 2008in and SN 2020jfo), to infer their physical parameters. These SNe exploded in the same host galaxy, M 61 (NGC 4303), at different epochs. SN 2008in was a normal Type IIP event with plateau length of ∼ 100 d and MV= –16.4 ± 0.4 mag, whereas SN 2020jfo was a short plateau (∼60 d) event with MV= –17.4 ± 0.4 mag. Hydrodynamical modeling on these events using the MESA+STELLA framework suggests that the progenitors of both the objects were Red Super Giant (RSG) stars with mass , but with different evolutionary history and environment.

In this poster, using the POSYDON code, we present results on binary progenitors of stripped-envelope SNe and their companions. We find that most progenitors are expected to explode, according to typical SN prescriptions (in contrast to single star progenitors). We also show the expected masses and position in the HR diagram of the companions of these SNe at the moment of explosion, allowing us to do a first statistical comparison with the compiled sample of observational detections (or upper limits) on these companions.

We investigate the physical properties of dust in the environment of three core-collapse supernovae (CCSNe) through mid-infrared (mid-IR) spectral energy distribution (SED) modeling (both analytical and numerical methods) and interpret our results within a Bayesian framework. We provide evidence that the observed late-time mid-IR excess of the SNe can be described by dust models. We conclude that in case of various types of SNe, numerical dust models with a shell-like geometry can be reconciled with analytical models, regarding the essential properties of dust grains.

The wealth of information obtained about massive stars from observations at ultraviolet (UV) wavelengths has been fundamental to understand their structure and the mechanisms regulating their evolution. There are however, important aspects that have not yet been addressed due to the lack of data and the relevant instrumentation such as the role of binarity and magnetic fields or the impact of low metallicity in the evolution of massive stars. There are plans to develop UV spectropolarimeters, UV monitors and very efficient telescopes with high collecting surfaces that will revolutionize the field. In this contribution, a short update on the current and foreseen UV instrumentation is provided.

The ESA/KU Leuven CubeSpec mission is specifically designed to provide low-cost space-based high-resolution optical spectroscopy. Here we highlight the science requirements and capabilities of CubeSpec. The primary science goal is to perform pulsation mode identification from spectroscopic line profile variability and empower asteroseismology of massive stars.

In this paper, we give a brief description of the Polstar instrument, an ultraviolet (UV) spectropolarimetric, Midex-class mission proposed to NASA to study the winds of massive stars as well as interstellar medium and protoplanetary discs topics.