On the High Metallicity Produced by cSNRs

Publications of the Astronomical Society of the Pacific, 1998

This paper reports on the workshop, 10 51 Ergs: The Evolution of Shell Supernova Remnants, hosted by the University of Minnesota, March 23-26, 1997. The workshop was designed to address fundamental dynamical issues associated with the evolution of shell supernova remnants and to understand better the relationships between supernova remnants and their environments. Although the title points only to classical, shell SNR structures, the workshop also considered dynamical issues involving X-ray filled composite remnants and pulsar driven shells, such as that in the Crab Nebula. Approximately 75 observers, theorists and numerical simulators with wide ranging interests attended the workshop. An even larger community helped through extensive on-line debates prior to the meeting to focus issues and galvanize discussion.

Astronomy and Astrophysics, 2001

We present a numerical simulation carried out in order to explain the complex morphology of the supernova remnant (SNR) 3C 400.2. Numerical simulations were done employing the new yguazú-a code (Raga et al. 2000). In the radio continuum, this remnant seems to be formed by two shells, which are partially overlapping (Dubner et al. 1994). Taking into account observational evidence such as a previous HI study (Giacani et al. 1998), we find that an adequate model for describing the morphology of the SNR 3C 400.2 is obtained by assuming that a single supernova (SN) explosion took place in a dense medium and close to an interface separating this medium from a lower density region. Besides, we also present a new deeper CCD Hα image mosaic of the northwest region of this SNR, which is composed of three single images. From the numerical results, we generated Hα emission maps, obtaining a good agreement with the observations.

Revista mexicana de astronomía y astrofísica

RESUMEN 3C 400.2 es un remanente de supernova galáctico que presenta una morfología que asemeja dos cascarones de diámetros diferentes que se traslapan. Estudiamos la cinemática de ambos cascarones para saber si esta morfología especial es debida al resultado de dos explosiones de supernova diferentes, o bien, a la explosión de unaúnica supernova en un medio que tenga un gradiente de densidad abrupto. Los datos cinemáticos concuerdan mejor con la segunda hipótesis. ABSTRACT 3C 400.2 is a galactic supernova remnant with a complex morphology consisting of two overlapping shells of different diameters: a large shell to the southeastern side and a small shell to the northwestern side. In order to decide whether this morphology is due to two supernova explosions or to the blow-out of one supernova explosion in a medium with a density gradient, we study the kinematics of both shells. Hα Fabry-Perot data are more in agreement with the scenario of only one supernova explosion undergoing a blow-out due to a density gradient in clumpy media.

Passer Journal of Basic and Applied Sciences

Supernova remnants (SNRs) are remarkable astronomical objects which are a diffuse, an expanding nebula of gas that is a direct result of a star's explosive death, resulting in a supernova explosion. SNRs play a vital role in the scattering of tough elements which are made in the supernova explosion into the interstellar medium and provide much amount of energy that heats the ISM, as well as its responsible for enormous differences in physical process and properties. In the present work, we study the physical properties, performance, and behavior of dynamical growth of several types (SNR Ia and II) specifically after an explosion of a supernova, and explore how the density of the interstellar environment affects the physical properties and eternity of each SNRs. To achieve such goals, we have utilized the method known as Counting Pixels Method, which has been applied to the SNRs images as well as a new pattern that has been suggested to calculate some of the physical properties such as the expansion velocity and the radius of the chosen remnants, which are based on the age of SNRs and the density of the surrounding medium. The outcomes of the study have depicted that each chosen SNRs type Ia and II likewise in performance and behavior after a long period of explosion Nevertheless, they are displaced either upwards or downwards based on the interstellar density. However, we noted that SNRs are exploded in the lower density environment and expanded without restriction to make a regular shape. We have concluded that further study is required particularly on the physical properties of SNRs when inserted into the radiative phase.

The Astrophysical Journal, 2003

We report on the results from a Chandra ACIS observation of the young, compact, supernova remnant N103B. The unprecedented spatial resolution of Chandra reveals sub-arcsecond structure, both in the brightness and in spectral variations. Underlying these small-scale variations is a surprisingly simple radial structure in the equivalent widths of the strong Si and S emission lines. We investigate these radial variations through spatially resolved spectroscopy using a plane-parallel, non-equilibrium ionization model with multiple components. The majority of the emission arises from components with a temperature of 1 keV: a fully ionized hydrogen component; a high ionization timescale (n e t> 10 12 s cm −3) component containing Si, S, Ar, Ca, and Fe; and a low ionization timescale (n e t∼10 11 s cm −3) O, Ne, and Mg component. To reproduce the strong Fe Kα line, it is necessary to include additional Fe in a hot (> 2 keV), low ionization (n e t∼10 10.8 s cm −3) component. This hot Fe may be in the form of hot Fe bubbles, formed in the radioactive decay of clumps of 56 Ni. We find no radial variation in the ionization timescales or temperatures of the various components. Rather, the Si and S equivalent widths increase at large radii because these lines, as well as those of Ar and Ca, are formed in a shell occupying the outer half of the remnant. A shell of hot Fe is located interior to this, but there is a large region of overlap between these two shells. In the inner 30% of the remnant, there is a core of cooler, 1 keV Fe. We find that the distribution of the ejecta and the yields of the intermediate mass species are consistent with model prediction for Type Ia events.

Physik Journal, 1988

Monthly Notices of the Royal Astronomical Society, 2010

We present constraints on the progenitor metallicities of core-collapse supernovae. To date, nearly all metallicity constraints have been inferred from indirect methods such as metallicity gradients in host galaxies, luminosities of host galaxies, or derived global galaxy metallicities. Here, progenitor metallicities are derived from optical spectra taken at the sites of nearby supernovae, from the ratio of strong emission lines found in their host HII regions. We present results from the spectra of 74 host HII regions and discuss the implications that these have on the nature of core-collapse supernova progenitors. Overall, while we find that the mean metallicity of type Ibc environments is higher than that of type II events, this difference is smaller than observed in previous studies. There is only a 0.06 dex difference in the mean metallicity values, at a statistical significance of ∼ 1.5 σ, while using a KS-test we find that the two metallicity distributions are marginally consistent with being drawn from the same parent population (probability >10%). This argues that progenitor metallicity is not a dominant parameter in deciding supernovae type, with progenitor mass and/or binarity playing a much more significant role. The mean derived oxygen metallicities (12+log(O/H)) for the different supernova types, on the Pettini & Pagel (2004) scale are; 8.580 (standard error on the mean of 0.027) for the 46 type II supernovae (dominated by type II plateau); 8.616 (0.040) for 10 type Ib; and 8.626 (0.039) for 14 type Ic. Overall the types Ibc supernovae have a mean metallicity of 8.635 (0.026, 27 supernovae). Hence we find a slight suggestion of a metallicity sequence, in terms of increasing progenitor metallicity going from type II through Ib and finally Ic supernovae arising from the highest metallicity progenitors. Finally we discuss these results in the context of all current literature progenitor metallicity measurements, and discuss biases and selection effects that may affect the current sample compared to overall supernova and galaxy samples.

Astronomy and Astrophysics, 2010

We present a detailed analysis of the XMM-Newton and Chandra X-ray data of the young Type Ia supernova remnant SNR 0519-69.0, which is situated in the Large Magellanic Cloud. We used data from both the Chandra ACIS and XMM-Newton EPIC MOS instruments, and high resolution X-ray spectra obtained with the XMM-Newton reflection grating spectrometer (RGS). Our analysis of the spatial distribution of X-ray line emission using the Chandra data shows that there is a radial stratification of oxygen, intermediate mass elements (IME) and iron, with the emission from more massive elements peaking more toward the center. Using a deprojection technique we measure a forward shock radius of 4.0 ± 0.3 pc and a reverse shock radius of 2.7 ± 0.4 pc. We took the observed stratification of the shocked ejecta into account in the modeling of the X-ray spectra, for which we used multicomponent non-equilibrium ionization models, with the components corresponding to layers dominated by one or two elements. An additional component was added in order to represent the shocked interstellar medium, which mostly contributed to the continuum emission. This multicomponent model fits the data adequately, and was also employed to characterize the spectra of distinct regions extracted from the Chandra data. From our spectral analysis we find that the approximate fractional masses of shocked ejecta for the most abundant elements are: M O ≈ 32%, M Si/S ≈ 7%/5%, M Ar+Ca ≈ 1% and M Fe ≈ 55%. From the continuum component we derive a circumstellar density of n H = 2.4 ± 0.2 cm −3 . This density, together with the measurements of the forward and reverse shock radii suggest an age of 0519-69.0 of 450 ± 200 yr, somewhat lower than, but consistent with the age estimate based on the extent of the light echo (600 ± 200 yr). Finally, from the high resolution RGS spectra we measured a Doppler broadening of σ = 1873 ± 50 km s −1 , from which we derive a forward shock velocity of v FS = 2770 ± 500 km s −1 . We discuss our results in the context of single degenerate explosion models, using semi-analytical and numerical modeling, and compare the characteristics of 0519-69.0 with those of other Type Ia supernova remnants.

The Astrophysical Journal, 2015

We present optical observations of supernova SN 2014C, which underwent an unprecedented slow metamorphosis from H-poor type Ib to H-rich type IIn over the course of one year. The observed spectroscopic evolution is consistent with the supernova having exploded in a cavity before encountering a massive shell of the progenitor star's stripped hydrogen envelope. Possible origins for the circumstellar shell include a brief Wolf-Rayet fast wind phase that overtook a slower red supergiant wind, eruptive ejection, or confinement of circumstellar material by external influences of neighboring stars. An extended high velocity Hα absorption feature seen in near-maximum light spectra implies that the progenitor star was not completely stripped of hydrogen at the time of core collapse. Archival pre-explosion Subaru Telescope Suprime-Cam and Hubble Space Telescope Wide Field Planetary Camera 2 images of the region obtained in 2009 show a coincident source that is most likely a compact massive star cluster in NGC 7331 that hosted the progenitor system. By comparing the emission properties of the source with stellar population models that incorporate interacting binary stars we estimate the age of the host cluster to be 30−300 Myr, and favor ages closer to 30 Myr in light of relatively strong Hα emission. SN 2014C is the best-observed member of a class of core-collapse supernovae that fill the gap between events that interact strongly with dense, nearby environments immediately after explosion and those that never show signs of interaction. Better understanding of the frequency and nature of this intermediate population can contribute valuable information about the poorly understood final stages of stellar evolution.

Astronomy & Astrophysics, 2018

A search for new supernova remnants (SNRs) has been conducted using TeV γ-ray data from the H.E.S.S. Galactic plane survey. As an identification criterion, shell morphologies that are characteristic for known resolved TeV SNRs have been used. Three new SNR candidates were identified in the H.E.S.S. data set with this method. Extensive multiwavelength searches for counterparts were conducted. A radio SNR candidate has been identified to be a counterpart to HESS J1534−571. The TeV source is therefore classified as a SNR. For the other two sources, HESS J1614−518 and HESS J1912+101, no identifying counterparts have been found, thus they remain SNR candidates for the time being. TeV-emitting SNRs are key objects in the context of identifying the accelerators of Galactic cosmic rays. The TeV emission of the relativistic particles in the new sources is examined in view of possible leptonic and hadronic emission scenarios, taking the current multiwavelength knowledge into account.