Related papers: iPTF14hls as a variable hyper-wind from a very mas…
We present ground-based and \textit{Swift} observations of iPTF16fnl, a likely tidal disruption event (TDE) discovered by the intermediate Palomar Transient Factory (iPTF) survey at 66.6 Mpc. The lightcurve of the object peaked at absolute…
We present a model for the steady state winds of super-Eddington systems. These radiatively driven winds are expected to be optically thick and clumpy as they arise from a porous atmosphere. The model is then used to derive the mass loss of…
We present optical UBVRI photometry and medium resolution spectroscopy of the type Ib supernova iPTF13bvn, spanning a phase of $\sim$ $-13\,$d to $+71\,$d with respect to $B$-band maximum. The post maximum decline rates indicate a fast…
We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope (UVOT) and constitute the first UV spectral series of a…
Observational implications are derived for two standard models of supernovae-driven galactic winds: a freely expanding steady-state wind and a wind sourced by a self-similarly expanding superbubble including thermal heat conduction. It is…
Mass loss through stellar winds plays a dominant role in the evolution of massive stars. In particular the mass-loss rates of very massive stars (VMSs, $> 100\,M_{\odot}$) are highly uncertain. Such stars display Wolf-Rayet spectral…
SN2006tf is the third most luminous SN discovered so far, after SN2005ap and SN2006gy. SN2006tf is valuable because it provides a link between two regimes: (1) luminous type IIn supernovae powered by emission directly from interaction with…
ASASSN-14ms may represent the most luminous Type Ibn supernova (SN~Ibn) ever detected, with an absolute U-band magnitude brighter than -22.0 mag and a total bolometric luminosity >1.0x10^{44} erg/s near maximum light. The early-time spectra…
Direct observational constraints on the earliest, stellar-wind-dominated phases of galactic outflows remain scarce. We present medium-resolution VLT/X-shooter spectroscopy of six Type I superluminous supernova (SLSN-I) host galaxies at z =…
In our ongoing study of eta Carinae's light echoes, there is a relatively bright echo that has been fading slowly, reflecting the 1845-1858 plateau of the eruption. A separate paper discusses its detailed evolution, but here we highlight…
We address the turbulent fragmentation scenario for the origin of the stellar initial mass function (IMF), using a large set of numerical simulations of randomly driven supersonic MHD turbulence. The turbulent fragmentation model…
We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our finely sampled light curves show a rise of 0.8mag within 2.5hr. Power-law fits [f(t)\sim(t-t_0)^n] to these data constrain the…
This letter complements a formation scenario of the progenitor of the supernova iPTF13bvn proposed in Hirai (2017). Although the scenario was successful in reproducing various observational features of the explosion and pre-explosion…
We present optical photometric and spectroscopic observations of the low-luminosity (LL) Type IIP supernova SN\,2024abfl. The distance to its host galaxy is highly uncertain, with independent estimates of $9.5^{+2.3}_{-2.4}$ Mpc and…
The hypothesis that the speed of light decreases by nearly 2 cm per sec and per year is discussed within the frame of a simple phenomenological model. It is shown that this hypothesis can provide an alternative explanation for the…
The tidal disruption of a star by a massive black hole is expected to yield a luminous flare of thermal emission. About two dozen of these stellar tidal disruption flares (TDFs) may have been detected in optical transient surveys. However,…
Spectra of the He I 10830 Angstrom line were obtained with NIRSPEC on the Keck 2 telescope for metal-deficient field giant stars. This line is ubiquitous in stars with T_eff greater than 4500K and M_V fainter than -1.5. Fast outflows are…
The detection by Rest et al. (2012) of light echoes from $\eta$ Carinae has provided important new observational constraints on the nature of its 1840's era giant eruption. Spectra of the echoes suggest a relatively cool spectral…
The massive evolved star Eta Carinae is the most luminous star in the Milky Way and has the highest steady wind mass-loss rate of any known star. Radiative transfer models of the spectrum by Hillier et al. predict that H-alpha is mostly…
Much difficulty has so far prevented the emergence of a consistent scenario for the origin of Type Ib and Ic supernovae (SNe). Here, we follow a heuristic approach by examining the fate of helium stars in the mass range 4 to 12Msun, which…