We present an optical nebular spectrum of the nearby Type Ia supernova 2011fe, obtained 981 days after explosion. SN 2011fe exhibits little evolution since the +593 day optical spectrum, but there are several curious aspects in this new extremely late-time regime. We suggest that the persistence of the $\sim5800$~Å feature is due to Na I D, and that a new emission feature at $\sim7300$~Å may be [Ca II]. Also, we discuss whether the new emission feature at $\sim6400$~Å might be [Fe I] or the high-velocity hydrogen predicted by Mazzali et al. The nebular feature at 5200~Å exhibits a linear velocity evolution of $\sim350$ $\rm km\ s^{-1}$ per 100 days from at least +220 to +980 days, but the line's shape also changes in this time, suggesting that line blending contributes to the evolution. At $\sim 1000$ days after explosion, flux from the SN has declined to a point where contribution from a luminous secondary could be detected. In this work we make the first observational tests for a post-impact remnant star and constrain its temperature and luminosity to $T \gtrsim 10^4$ $\rm K$ and $L \lesssim 10^4$ $\rm L_{\odot}$. Additionally, we do not see any evidence for narrow H$α$ emission in our spectrum. We conclude that observations continue to strongly exclude many single-degenerate scenarios for SN 2011fe.
Non-LTE time-dependent spectroscopic modelling of type II-plateau supernovae from the photospheric to the nebular phase: case study for 15 and 25Msun progenitor stars
The kinematics of the nebular shells around low mass progenitors of PNe with low metallicity
我们分析了26个行星状星云(PNe)的内部运动学与低金属丰度,似乎来自最低质量的祖星,包括晕PN人口。基于从圣佩德罗·马蒂尔PNe运动学目录(López et al. 2012)中绘制的空间分辨长缝中阶梯光栅光谱,我们根据迄今为止用于此目的的最大样本测量其全球膨胀速度来表征这些PNe的运动学。我们发现运动学,遵循在其他研究中观察到和预测的趋势,但也发现,大多数的PNe研究在这里往往有膨胀速度小于20公里/秒,在所有考虑的发射线。我们在这个具有低质量祖先的低金属丰度行星状星云样本中观察到的低膨胀速度很可能是微弱的中央星风驱动星云壳运动学的结果。这项研究补充了以前的结果(Pereyra等人,2013年,以及其中的参考文献),这些结果将PN壳的膨胀速度与中心恒星的特征联系起来。
We use non-local thermal equilibrium radiative transport modeling to examine observational signatures of sub-Chandrasekhar mass double detonation explosions in the nebular phase. Results range from spectra that look like typical and subluminous Type Ia supernovae (SNe) for higher mass progenitors to spectra that look like Ca-rich transients for lower mass progenitors. This ignition mechanism produces an inherent relationship between emission features and the progenitor mass as the ratio of the nebular [Ca II]/[Fe III] emission lines increases with decreasing white dwarf mass. Examining the [Ca…
Co-spatial Long-slit UV/Optical Spectra of Ten Galactic Planetary Nebulae with HST/STIS II. Nebular Models, Central Star Properties and He+CNO Synthesis
SN 2017ein is a narrow-lined Type Ic SN that was found to share a location with a point-like source in the face on spiral galaxy NGC 3938 in pre-supernova images, making SN 2017ein the first credible detection of a Type Ic progenitor. Results in the literature suggest this point-like source is likely a massive progenitor of 60-80 M$_{\odot}$, depending on if the source is a binary, a single star, or a compact cluster. Using new photometric and spectral data collected for 200 days, including several nebular spectra, we generate a consistent model covering the photospheric and nebular phase usin…
Optical and near-infrared nebular-phase spectroscopy of SN 2024ggi: constraints on the structure of the inner ejecta, progenitor mass, and dust
Millennium Institute of Astrophysics MAS(天体物理学千年研究所);Gemini Observatory, NSF's National Optical-Infrared Astronomy Research Laboratory(Gemini 天文台,美国国家光学红外天文研究实验室)
Multidimensional Models of Type Ia Supernova Nebular Spectra: Strong Emission Lines from Stripped Companion Gas Rule Out Classic Single Degenerate Systems
Near-infrared spectral evolution of the Type Ia supernova 2014J in the nebular phase: implications for the progenitor system
SN 2014 J是数十年来最接近的Ia型超新星,除了燃烧产物分布外,它还提供了一个独特的机会,可以详细研究祖先系统和爆炸机制的观测特征。我们提出了一个晚的时间近红外光谱系列Gemini-N在$307-466$天后爆炸。在$H$带演化之后,探测放射性铁族元素的分布、混合的程度以及膨胀喷出物中磁场的存在。比较孤立的$1.6440$ $μ$ m [Fe II]发射线与合成模型显示出一致性,与一颗$ρ_c=0.7\times10^9$ g cm ${}^{-3}$质量的白矮星经历延迟爆轰。相邻的$1.54$ $μ$ m发射特征中的通量与$1.6440$ $μ$ m特征中的通量的比率显示了在中心区域中稳定的和放射性的铁族元素的一些有限混合的证据。此外,$1.6440$ $μ$ m线的演变显示出有趣的不对称性。当测量线宽的这一功能,数据显示的合成光谱,对应于$\approx1{,}000$公里秒${}^{-1}$,这可能是由一个本地化的过渡到爆炸产生不对称电离的喷出物的演变中看不到的线宽增加。利用不同时期之间的宽度差异,中心区域的不对称分量(大约对应于白矮星质量的内部$2\times10^{-4}$)表明初始爆炸的偏心点火,因此运动中心与化学中心的点火。其他几个模型的调查,包括他爆炸和合并,有困难再现这些光谱的功能。
We present a new method for constraining the mass transfer evolution of low mass X-ray binaries (LMXBs) - a reverse population synthesis technique. This is done using the detailed 1D stellar evolution code MESA (Modules for Experiments in Stellar Astrophysics) to evolve a high-resolution grid of binary systems spanning a comprehensive range of initial donor masses and orbital periods. We use the recently developed Convection And Rotation Boosted (CARB) magnetic braking scheme. The CARB magnetic braking scheme is the only magnetic braking prescription capable of reproducing an entire sample of …
Nebular Spectra of the Extremely Metal-Poor SN II 2023ufx Over a Year After Explosion: A Massive Progenitor and Unique Circumstellar Environment
Center for Cosmology and AstroParticle Physics(宇宙学与暗物质粒子物理中心);Department of Astronomy, The Ohio State University(俄亥俄州立大学天文学系);Institut d’Astrophysique de Paris, CNRS-Sorbonne Université(巴黎天体物理学研究所,法国国家科学研究中心-索邦大学);French-Chilean Laboratory for Astronomy, IRL 3386, CNRS, Instituto de Astrofísica, Pontificia Universidad Católica de Chile(法智利天文学联合实验室,法国国家科学研究中心,智利天主教Pontificia大学天体物理研究所)
Type II-P Supernova Progenitor Star Initial Masses and SN 2020jfo: Direct Detection, Light Curve Properties, Nebular Spectroscopy, and Local Environment
We present nebular spectra of the Type Ia supernova (SN Ia) SN 2019yvq, which had a bright flash of blue and ultraviolet light after exploding, followed by a rise similar to other SNe Ia. Although SN 2019yvq displayed several other rare characteristics such as persistent high ejecta velocity near peak brightness, it was not especially peculiar and if the early "excess" emission were not observed, it would likely be included in cosmological samples. The excess flux can be explained by several different physical models linked to the details of the progenitor system and explosion mechanism. Each …
We present high-cadence optical and ultraviolet light curves of the normal Type Ia supernova (SN) 2021aefx, which shows an early bump during the first two days of observation. This bump may be a signature of interaction between the exploding white dwarf and a nondegenerate binary companion, or it may be intrinsic to the white dwarf explosion mechanism. In the case of the former, the short duration of the bump implies a relatively compact main-sequence companion star, although this conclusion is viewing-angle dependent. Our best-fit companion-shocking and double-detonation models both overpredi…
We present SN 2020jfo, a Type IIP supernova in the nearby galaxy M61. Optical light curves from the Zwicky Transient Facility, complemented with data from Swift and near-IR photometry are presented. The 350-day duration bolometric light curve exhibits a relatively short (~ 65 days) plateau. This implies a moderate ejecta mass (~ 5 Msun). A series of spectroscopy is presented, including spectropolarimetric observations. The nebular spectra are dominated by Halpha but also reveal emission lines from oxygen and calcium. Comparisons to synthetic nebular spectra indicate an initial progenitor mass …
Supernova (SN) 2021ocs was discovered in the galaxy NGC 7828 ($z = 0.01911$) within the interacting system Arp 144, and subsequently classified as a normal type-Ic SN around peak brightness. VLT/FORS2 observations in the nebular phase at 148 d reveal that the spectrum is dominated by oxygen and magnesium emission lines of different transitions and ionization states: O I, [O I], [O II], [O III], Mg I, and Mg II. Such a spectrum has no counterpart in the literature, though it bears a few features similar to those of some interacting type Ibn and Icn SNe. Additionally, SN 2021ocs showed a blue co…
There is a wide consensus that type Ia supernovae (SN Ia) originate from the thermonuclear explosion of CO white dwarfs (WD), with the lack of hydrogen in the observed spectra as a distinctive feature. Here, we present SN 2016jae, which was classified as a Type Ia SN from a spectrum obtained soon after the discovery. The SN reached a B-band peak of -17.93 +- 0.34 mag, followed by a fast luminosity decline with sBV 0.56 +- 0.06 and inferred Dm15(B) of 1.88 +- 0.10 mag. Overall, the SN appears as a "transitional" event between "normal" SNe Ia and very dim SNe Ia such as 91bg-like SNe. Its peculi…
The nature of the peculiar `Ca-rich' SN 2019ehk in the nearby galaxy M100 remains unclear. Its origin has been debated as either a stripped core-collapse supernova or a thermonuclear helium detonation event. Here, we present very late-time photometry of the transient obtained with the Keck I telescope at $\approx280$ days from peak light. Using the photometry to perform accurate flux calibration of a contemporaneous nebular phase spectrum, we measure an [O I] luminosity of $(0.19-1.08)\times10^{38}$ erg s$^{-1}$ and [Ca II] luminosity of $(2.7-15.6)\times10^{38}$ erg s$^{-1}$ over the range of…
We present JWST near- and mid-infrared spectroscopic observations of the nearby normal Type Ia supernova SN 2021aefx in the nebular phase at $+255$ days past maximum light. Our Near Infrared Spectrograph (NIRSpec) and Mid Infrared Instrument (MIRI) observations, combined with ground-based optical data from the South African Large Telescope (SALT), constitute the first complete optical $+$ NIR $+$ MIR nebular SN Ia spectrum covering 0.3$-$14 $μ$m. This spectrum unveils the previously unobserved 2.5$-$5 $μ$m region, revealing strong nebular iron and stable nickel emission, indicative of high-den…
Peak 'Nebular' Emission and Early Flux Excesses in Ca-strong Supernovae
Trinity College Dublin, the University of Dublin(都柏林三一学院,都柏林大学);University of Portsmouth(朴茨茅斯大学);California Institute of Technology(加州理工学院);University of Warwick(华威大学);Queen’s University Belfast(贝尔法斯特女王大学);Stockholm University(斯德哥尔摩大学);Purdue University(普渡大学)