Related papers: Time-Varying Sodium Absorption in the Type Ia Supe…

Recent observations have revealed that some Type Ia supernovae exhibit narrow, time-variable Na I D absorption features. The origin of the absorbing material is controversial, but it may suggest the presence of circumstellar gas in the…

Type Ia supernovae (SNe Ia) are thermonuclear runaways in certain white dwarfs in binary systems. They have been extensively studied, yet their progenitor and explosion mechanisms remain poorly understood. We study a large sample of SNe Ia…

Na I D absorbing systems toward Type Ia supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is…

Nearby type Ia supernovae (SNe Ia), such as SN 2017cbv, are useful events to address the question of what the elusive progenitor systems of the explosions are. Hosseinzadeh et al. (2017) suggested that the early blue excess of the…

One of the main questions concerning Type Ia supernovae is the nature of the binary companion of the exploding white dwarf. A major discriminant between different suggested models is the presence and physical properties of circumstellar…

We study the properties of low-velocity material in the line of sight towards nearby Type Ia Supernovae (SNe Ia) that have measured late phase nebular velocity shifts (v_neb), thought to be an environment-independent observable. We have…

Narrow interstellar absorption features in supernova (SN) spectra serve as valuable diagnostics for probing dust extinction and the presence of circumstellar or interstellar material. In this third paper in a series, we investigate how the…

Patat et al. recently inferred the existence of circumstellar material around a normal Type Ia supernova (SN) for the first time, finding time-variable Na I D absorption lines in the spectrum of SN 2006X. We present high-resolution…

A key tracer of the elusive progenitor systems of Type Ia supernovae (SNe Ia) is the detection of narrow blueshifted time-varying Na I D absorption lines, interpreted as evidence of circumstellar material (CSM) surrounding the progenitor…

In studies on intermediate- and high-resolution spectra of Type Ia supernovae (SNe Ia), some objects exhibit narrow Na-I D absorptions often blueshifted with respect to the rest wavelength within the host galaxy. The absence of these in…

Progenitors of Type Ia supernovae (SNe) have been predicted to modify their ambient circumstellar (CSM) and interstellar environments through the action of their powerful winds. While there is X-ray and optical evidence for circumstellar…

The origin of strong sodium absorption, which has been observed for a few nearby Type Ia supernovae (SNe Ia), remains elusive. Here we analyse two high-signal-to-noise, intermediate-resolution VLT/X-shooter spectra at epochs $+$18 and $+$27…

We propose that the sodium responsible for the variable NaI D absorption lines in some type Ia supernovae (SN Ia) originate mainly from dust residing at ~1 pc from the supernovae. In this Na-from-dust absorption (NaDA) model the process by…

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the…

Early polarization observations on Type Ia supernovae (SNe Ia) may reveal the geometry of supernova ejecta, and then put constraints on their explosion mechanism and their progenitor model. We performed a literature search of SNe Ia with…

Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the…

Type Ia supernovae (SNe Ia) play key roles in revealing the accelerating expansion of the universe, but our knowledge about their progenitors is still very limited. Here we report the discovery of a rigid dichotomy in circumstellar (CS)…

I present an overview of optical observations (mostly spectra) of Type II, Ib, and Ic supernovae (SNe). SNe II are defined by the presence of hydrogen, and exhibit a very wide variety of properties. SNe II-L tend to show evidence of…

We present single-epoch, post-maximum spectropolarimetry of four Type Ia supernovae (SNe Ia) that span a range of spectral and photometric properties: SN 2002bf and SN 2004dt exhibit unusually high-velocity (HV) absorption lines. SN 1997dt…

While O is often seen in spectra of Type Ia supernovae (SNe Ia) as both unburned fuel and a product of C burning, C is only occasionally seen at the earliest times, and it represents the most direct way of investigating primordial white…