Supernova Outburst Research Articles

Comparative Modeling of the 2012b Outburst of Supernova 2009ip

Comparative Modeling of the 2012b Outburst of Supernova 2009ip

Comparative Modeling of the 2012b Outburst of Supernova 2009ip

The September 2012 outburst of the type IIn supernova 2009ip was simulated using two independent codes, STELLA and FRONT. The UBVRI light curves obtained agree well with one another and with observational data. Special attention is given to the dynamics of the emerging dense shell, which determines the luminosity of the object and is used for the direct method of determining the distance to the supernova. Two-dimensional spectral radiation-hydrodynamics computations of the SN 2009ip model were carried out, which confirmed the conclusion about the stability of this shell on the times scales of the method application.

Magnetar SGR 1900+14 as a Potential Source of Galactic Cosmic Rays with Energies Above 1020 eV

The analysis of the influence of the Galactic magnetic field on the trajectory of cosmic rays of extremely high energies (EHECR, E > 1020 eV) detected by Auger and Telescope Array (TA) detectors shows that the magnetar SGR 1900+14 is a potential Galactic source of the EHECR triplet – three events in a circle of radius 2° in the vicinity of the Galactic Center (l = 35°, b = –4°). Magnetar SGR 1900+14 – a neutron star with magnetic field of the order of 1015 G – was formed as a result of the Supernova outburst 1000…6000 years ago. In our work we investigate possible manifestations of cosmic rays accelerated by the Supernova remnant’s shock, due to their interaction with the molecular clouds of the interstellar medium in the vicinity of Supernova. In particular, the possibility of such a gamma-ray emission model of the newly discovered unidentified TeV gamma-ray source 2HWC J1907+084 is analyzed.

Eruptive Variables

In this paper, a solution of the problem about how a massive star knows that it gets rid of its excess of mass before it can become a white dwarf, a pulsar or a black hole, is proposed. Many astronomers believe that this may take place in the form of a nova and supernova outburst, as well as in the form of a continuous outflow of gas [1].

Нейтронная звезда: от экстремальной турбулентности вспышки сверхновой к эталонной монотонности когерентного излучения пульсара

Нейтронная звезда: от экстремальной турбулентности вспышки сверхновой к эталонной монотонности когерентного излучения пульсара

Spallation reactions in shock waves at supernova explosions and related problems

The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e. the carbon-detonation supernova. A key role of spallation reactions in the formation of isotopic anomalies in the primordial matter of the Solar System is revealed. It is conditioned by the diffusive acceleration of particles in the explosive shock waves, which leads to the amplification of rigidity of the energy spectrum of particles and its enrichment with heavier ions. The quantitative calculations of such isotopic anomalies of many elements are presented. It is well-grounded that the anomalous Xe-HL in meteoritic nanodiamonds was formed simultaneously with nanodiamonds themselves during the shock wave propagation at the Sn Ia explosion. The possible effects of shock wave fractionation of noble gases in the atmosphere of planets are considered. The origin of light elements Li, Be and B in spallation reactions, predicted by Fowler in the middle of the last century, is argued. All the investigated isotopic anomalies give the evidence for the extremely high magneto- hydrodynamics (MHD) conditions at the initial stage of free expansion of the explosive shock wave from Sn Ia, which can be essential in solution of the problem of origin of cosmic rays. The specific iron-enriched matter of Sn Ia and its MHD-separation in turbulent processes must be taking into account in the models of origin of the Solar System.

Chiral effect of electrons from supernova outbursts in the neutron fireball model

The previously proposed idea about the possible role of neutrons released during the supernova (SN) outburst as a source of polarized electrons causing chiral asymmetry of organic molecules in interstellar gas—dust clouds is developed. A specific physical mechanism of removal of a large number of free neutrons beyond the dense SN shell via the relativistic neutron fireball with a Lorentz factor on the order of 100 is considered. Estimations show high efficiency of the chiral effect of electrons from the SN in the mechanism under consideration.

Boundary conditions for simulations of the thermal outburst of a type Ia supernova

We present a technique to calculate the boundary conditions for simulations of the development of large-scale convective instability in the cores of rotating white-dwarf progenitors of type Ia supernovae. The hydrodynamical equations describing this situation are analyzed. We also study the impact of the boundary conditions on the development of the thermal outburst.

Strmömgren zones of type II supernovae

The emission measures EM in the directions of supernova remnants and pulsars are considered as functions of their ages t. The resulting plot has a well-defined lower boundary, which can be approximated by the expression EMmin∝1/t. The quantity EMmin increases with decreasing age t and does not level off or reach a maximum until t≅500 yr. It is concluded that the bulk of the radiative energy that goes into ionizing and heating the interstellar gas is released at early stages of the supernova remnant’s evolution. We suggest that most of the kinetic energy of the supernova shell is converted into thermal energy and radiated at remnant ages t<100 yr, when the supernova shell, which is expanding at an enormous speed (about 104 km/s), overtakes the shell produced by the presupernova in the supergiant stage. We have estimated the ionization energy E≅1051 erg, diameter L≅60 pc, and electron density N e≅7 cm−3 of the HII regions around the supernovae (the supernova Stromgren zones). A list of objects that can be reliably identified as Stromgren zones of type II supernovae is presented. The plot of pulsar pulse broadening τ as a function of the pulsar age t also has a well-defined lower boundary, for which τ∝t −2 when t≥1000 yr. This suggests that turbulence develops during the first thousand years after the supernova outburst. It is also concluded that turbulence plays an important role in the formation and evolution of the Stromgren zones of type II supernovae.

Infrared emission towards SN 1987A, 11 years after outburst: Properties of the circumstellar dust

Detailed models are presented for the late epoch mid infrared (MIR) emission from collisionally heated grains in the shocked circumstellar gas around SN 1987A. Thermal dust emission from a region of moderate density interior to the thick inner ring seen with the Hubble Space Telescope (HST) is found to be a natural explanation for the MIR spectral energy distribution measured by ISOCAM. The MIR-spectrum can be reproduced by a mixture of silicate-iron or silicate-graphite grains or by a composition of pure graphite grains. A composition of pure iron grains on the other hand can be excluded and a pure silicate composition does not seem to be very likely. The dust-to-gas ratio in the interaction zone is ∼0.01%, an order of magnitude lower than estimates for dust abundances in the winds of red supergiant (RSG) stars in the LMC. This low dust abundance can be accounted for by a combination of evaporation through the UV-flash from the supernova outburst and subsequent sputtering in the shocked gas. For this explanation to hold, dust in the pre-supernova circumstellar medium (CSM) would have to have been predominantly composed of grains other than graphite, with a maximum size smaller than ∼0.1 µm.

Bounds on the possible evolution of the gravitational constant from cosmological type-Ia supernovae

Recent high-redshift type-Ia supernovae results can be used to set new bounds on a possible variation of the gravitational constant G. If the local value of G at the space-time location of distant supernovae is different, it would change both the kinetic energy release and the amount of ${}^{56}\mathrm{Ni}$ synthesized in the supernova outburst. Both effects are related to a change in the Chandrasekhar mass ${M}_{\mathrm{Ch}}\ensuremath{\propto}{G}^{\ensuremath{-}3/2}.$ In addition, the integrated variation of G with time would also affect the cosmic evolution and therefore the luminosity distance relation. We show that the later effect in the magnitudes of type-Ia supernovae is typically several times smaller than the change produced by the corresponding variation of the Chandrasekhar mass. We investigate in a consistent way how a varying G could modify the Hubble diagram of type-Ia supernovae and how these results can be used to set upper bounds to a hypothetical variation of G. We find ${G/G}_{0}\ensuremath{\lesssim}1.1$ and $\ifmmode \dot{G}\else \.{G}\fi{}/G\ensuremath{\lesssim}{10}^{\ensuremath{-}11}{\mathrm{yr}}^{\ensuremath{-}1}$ at redshifts $z\ensuremath{\simeq}0.5.$ These new bounds extend the currently available constraints on the evolution of G all the way from solar and stellar distances to typical scales of Gpc/Gyr, i.e., by more than 15 orders of magnitude in time and distance.

The late-time expansion of the ejecta of SN 1987A

The evolution of the shape and size of the ejecta of SN 1987A is analyzed over a period of ~ 8 years based on HST images and spectra taken between 1278 and 4336 days after the supernova outburst. We combine both proprietary and archival HST data obtained with the FOC, WFPC2 and STIS. The low resolution near-UV prism FOC spectrum obtained at day 3043 has not been described previously. Although the FWHM of the ejecta grew linearly over the time span studied, the appearance of the SN envelope also changed markedly with wavelength. At visible wavelengths (lambda ~ 5000 Angstrom) the ejecta became progressively more elongated, reaching an ellipticity epsilon ~ 0.25 by day 4000. In the near-UV (lambda ~ 2500 AA), the ejecta remained closely circular (epsilon <= 0.1) and ~ 50% larger in angular extent than in the visible. The FOC prism observations show that the large extent of the SN envelope is confined to a grouping of resonance lines spanning Mg I 2852, Mg II 2795,2802 and several Fe II multiplets -- thereby confirming that the larger size of the debris in the near-UV is due to scattering in these optically thick transitions compared to the optically thin forbidden and semi-forbidden transitions that dominate the visible spectrum. The available data are not of sufficient quality to detect the slight deviation from linear expansion expected for the outermost regions of the near-UV images as predicted by Chugai et al. (1997).

Hubble Space Telescope Spectroscopic Observations of the Ejecta of SN 1987A at 2000 Days

We have used the Faint Object Spectrograph on the Hubble Space Telescope to observe the spectra of SN 1987A over the wavelength range 2000 -- 8000\ \AA\ on dates 1862 and 2210 days after the supernova outburst. Even these pre-COSTAR observations avoid much of the contamination from the bright stars nearby and provide a very useful set of line strengths and shapes for analysis. The spectrum is formed in an unusual physical setting: cold gas which is excited and ionized by energetic electrons from the radioactive debris of the supernova explosion. The spectra of SN 1987A at this phase are surprisingly similar to those of the nova shells of CP Puppis and T Pyxidis decades after outburst. SN 1987A and the novae are characterized by emission from material with electron temperatures of only a few hundred degrees Kelvin, and show narrow Balmer continuum emission and strong emission lines from O$^+$. The Balmer continuum shape requires the electron temperature in the supernova ejecta to be as low as 500 K on day 1862 and 400 K on day 2210 after outburst. The \OIIUV\ doublet is surprisingly strong and is plausibly powered by collisional ionization of neutral oxygen to excited states of O$^+$. The line intensity ratio of the \OID\ doublet obtained from Gaussian fits of the line profiles is 1.8$\pm0.2$, contrary to the optically thin limit of 3. This ratio is {\it not} due to an optical depth effect, but rather is an artifact of assuming a Gaussian profile to fit the \OID\ doublet profile. Specifying the line ratio $R\, = \, F([{\rm OI}]6300)/F([{\rm OI}]6364)$ = 3 is consistent with the data and allows a calculation of the decomposed line profile. All the observed strong lines are found to be blueshifted by a similar amount

Detection of X-rays from SN 1987A with ROSAT

Soft X-rays (0.5-2 keV) were detected with the ROSAT Position-Sensitive Proportional Counter (PSPC) from the direction of SN 1987A, which falls within an association in the Large Magellanic Cloud (LMC) that is rich in B stars. The emission is consistent with two point sources in the LMC with total luminosity of approximately 10(exp 34) ergs/s. The brighter source is identified with SN 1987A on the basis of its positional agreement. We interpret the emission as arising from the interaction of supernova ejecta with the pre-existing blue giant wind. The second source may be an unidentified Be/X-ray binary. Another possibility is that the second source is an X-ray echo from the supernova outburst. The X-ray echo interpretation reqires that the supernova emitted approximately 10(exp 47) ergs in a burst of soft X-rays.

THE NARROW EMISSION LINES FROM SN 1987A

ABSTRACT Observations of the narrow lines from SN 1987A have been reviewed, along with model interpretations of these observations. In addition, a discussion is provided on characteristics of the radiation from the supernova outburst, and how this affects the thermal structure of the circumstellar gas. Preliminary results from 2D hydrodynamical calculations for the circumstellar structure are also presented.

Circumstellar emission from SN 1987A

The ionization of the circumstellar medium of SN 1987A by hard radiation following the supernova outburst is analyzed. Particular emphasis is placed on circumstellar UV and optical emission lines from the supernova. The observations are well modeled by a circumstellar shell, ionized by the strong soft X-ray burst during the first hours after the explosion. After the initial nearly complete ionization, the shell recombines into the observed ionization stages. At the breakout, the shell is heated to ∼10 5 K, subsequently cooling to ∼5×10 4 K in ∼300 days, in agreement with optical observations

50–500 MeV observations of LMC supernova 1987A

Since the discovery of the supernova outburst in the LMC in 1987, we have made two attempts (on day 55 and day 407) to measure the high energy gamma-ray flux in the range 50–500 MeV, by using a balloon borne spark chamber telescope. On day 55, no positive signal was seen from the source. A 3σ upper limit of 2.9 × 10 −5 ph cm −2 s −1 was obtained after the analysis of the spark chamber data. Preliminary analysis of the quick look data obtained in the second flight shows that the gamma-ray flux even on day 407 was less than 9 × 10 −4 ph cm −2 s −1 (3 σ).

The progenitor of SN1987A

One of the reasons why the bright supernova SN1987A is of such importance is the fact that its proximity would allow for the first time, the identification of a supernova progenitor star. Attempts to establish which star was the progenitor have led to uncertainties, however. Here we use spatial and spectroscopic information from International Ultraviolet Explorer (IUE) spectra in the range 1,150–1,950A to demonstrate that Sk–69 202, the star coinciding positionally with the Large Magellanic Cloud (LMC) supernova, has disappeared from sight. Two weaker sources, named star 2 and star 3 in the astrometric analysis of the image of Sk–69 202 before the supernova outburst, are still present in the ultraviolet spectra. We isolate their spectra and give a spectral classification. We conclude that Sk-69 202 is the progenitor the LMC supernova.

The light of the supernova outburst. IV - Lowered energy for the echo model

view Abstract Citations (2) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Light of the Supernova Outburst. IV. Lowered Energy for the Echo Model Mackey, Willie R. Abstract Type I supernovae exhibit three uniform features, of which the first two are observational: (1) monotonic quasi-exponential light curve; (2) characteristic shifting spectral features; (3) total energy release limited to E0 ≈ 1051ergs. The fluorescence-echo model of Type I supernovae required a total energy of E0 ≈ 1052ergs to explain phenomena (1) and (2); it violated (3). On reconsideration of the energetics it is shown here that resonance scattering of the He II Lyman photons within the circumstellar shell decreases by one order of magnitude the UV excitation energy required to fit the observed features with the echo model. This lowers the total energy required by a factor of 10. The expected values of total energy released during the explosion between the echo model and that of the cobalt decay are now concordant. Publication: The Astrophysical Journal Pub Date: April 1987 DOI: 10.1086/165129 Bibcode: 1987ApJ...315..251M Keywords: Astronomical Models; Luminosity; Resonance Scattering; Supernovae; Abundance; Balmer Series; Forbidden Transitions; H Lines; Red Shift; Astrophysics; INTERSTELLAR: MATTER; STARS: SUPERNOVAE full text sources ADS | data products SIMBAD (1) NED (1)

Supernova almost on the doorstep

Last week's discovery of a supernova outburst in the Larger Magellanic Cloud is an important opportunity for astronomers of several kinds, but one chance has been missed already.