Large Magellanic Cloud Supernova Research Articles

Maximum Energies of Shock‐accelerated Electrons in Large Magellanic Cloud Supernova Remnants

Some supernova remnant X-ray spectra show evidence for synchrotron emission from the extension of the electron spectrum that produces radio synchrotron emission. For any remnant, if the extrapolated radio flux exceeds the observed X-ray flux, thermal or nonthermal, a roll-off of the relativistic electron energy distribution must occur below X-ray-emitting energies. We have studied the X-ray emission from 11 remnants in the Large Magellanic Cloud to constrain this roll-off energy. We assume that the electron distribution is a power law with an exponential cutoff at some Emax and radiates in a uniform magnetic field. If the radio flux and spectral index are known, this simple model for the synchrotron contribution depends on only one parameter that relates directly to Emax. Here we have modeled the X-ray spectra by adding a component for thermal radiation of a Sedov blast wave to the synchrotron model. For all 11 supernova remnants in this sample, the limits for Emax range between 10 and 80 TeV (for a mean magnetic field of 10 μG). This result is similar to a study of Galactic remnants in which 13 out of 14 objects had limits between 20 and 80 TeV. We interpret Emax in the context of shock acceleration theories. Better data and models should allow either firm detections of nonthermal components or more restrictive limits on Emax.

Supernova Remnants in the Magellanic Clouds. I. The Colliding Remnants DEM L316

The Large Magellanic Cloud (LMC) supernova remnant (SNR) DEM L316 is of considerable interest, as it shows two overlapping shells at radio and optical wavelengths. This morphology suggests that DEM L316 is in fact two SNRs, which may or may not be spatially connected. We have observed the DEM L316 remnants at optical, radio, and X-ray wavelengths in order to address the question of whether the SNRs are interacting, and if so, whether a tunnel might have formed between the remnants, allowing them to equilibrate. Besides the connecting shell morphologies at optical and radio wavelengths, our observations show enhanced [O III] emission at the juncture between the shells, enhanced X-ray emission from one shell at that juncture, and a change in the structure of the magnetic field near the interaction region. These factors strongly imply that the two remnants are indeed colliding. In addition, we have done a detailed study on the physical properties of the remnants, including an examination of thermal and kinetic energies and of the balance of thermal and magnetic pressures.

ASCA observations of the Large Magellanic Cloud supernova remnant sample: Typing supernovae from their remnants

We present our first results from a study of the supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using data from ASCA. The three remnants we have analyzed to date, 0509-67.5, 0519-69.0, and N103B, are among the smallest, and presumably also the youngest, in the Cloud. The X-ray spectra of these SNRs show strong Hα emission lines of silicon, sulfur, argon, and calcium with no evidence for corresponding lines of oxygen, neon, or magnesium. The dominant feature in the spectra is a broad blend of emission lines around 1 keV which we attribute to L- shell emission lines of iron. Model calculations (Nomoto, Thielemann, & Yokoi 1984) show that the major products of nucleosynthesis in Type Ia supernovae (SNs) are the elements from silicon to iron, as observed here. The calculated nucleosynthetic yields from Type Ib and II SNs are shown to be qualitatively inconsistent with the data. We conclude that the SNs which produced these remnants were of Type Ia. This finding also confirms earlier suggestions that the class of Balmer-dominated remnants arise from Type Ia SN explosions. Based on these early results from the LMC SNR sample, we find that roughly one-half of the SNRs produced in the LMC within the last ~1500 yr came from Type Ia SNs.

Neutrino astrophysics and SN 1987 A(*)(**)

In this paper we summarize the Mont Blanc observation of the Large Magellanic Cloud supernova, exploded on February 23, 1987. The problem of two bursts, recorded in different underground detectors and separated in time by 4.7 hours, is also discussed. Since the different observations are not contradictory from the experimental point of view, some changements are required in the current predictions of the theoretical models of a gravitational stellar collapse in order to fit all the experimental data. Finally, the combined analysis of the data, recorded in all the neutrino and gravitational wave detectors running at the time of the supernova, clearly indicates a long duration of the phenomenon. Thus, any serious (even if difficult) tentative to explain how a star ends its life as a supernova should be based on all the experimental data available, recorded in different, independent experiments running at intercontinental distances at the time of supernova 1987 A.

Measurements of the diameter of the Large Magellanic Cloud supernova SN 1987A

We present direct measurements of the angular diameter of SN 1987A in the Large Magellanic Cloud (LMC) made from high-angular resolution observations at the CTIO 4 m telescope in five observing runs from 1987 April to 1988 April. Diameters were determined to milliarcsecond precision from integrated power spectra, using speckle interferometric data. The accuracy of the technique was evaluated by laboratory experiments and measurements of the diameters of several stars of known angular size. The SN 1987A diameters measured near the center of the Hα line show clear evolution during this period. The rate at which the supernova size changed at this wavelength corresponds to 2850 km s^-1^ mean velocity of expansion. Diameter measurements obtained in several spectral lines and in the continuum indicate stratification of the expanding envelope of the supernova. Our continuum data yield diameters substantially larger than those calculated from photometric measurements and a blackbody fit to the observed spectra.

Limits on mass of the neutrino.

A likelihood analysis using energies and arrival times for electron neutrinos from the Large Magellanic Cloud supernova suggests that the neutrino mass is less than about 5 eV at a confidence level of 90% and less than about 10 eV at a confidence level near 99%.

IRAS Observations of Collisionally Heated Dust in Large Magellanic Cloud Supernova Remnants

AbstractIRAS additional observations show that luminous (104−105 L⊙) far-IR sources are associated with the Large Magellanic Cloud (LMC) supernova remnants N63A, N49, N49B, and N186D. Comparison of the IRAS and X-ray data shows that a substantial fraction of the IR emission from three of the SNRs can be accounted for by collisionally heated dust. The ratio of dust-grain cooling to total atomic cooling is ~10 in X-ray emitting gas (T~106 K). We show why dust cooling does not dominate, but probably speeds SNR evolution in an inhomogeneous interstellar medium.

Particle Physics Implications of the "Neutrino" Burst from the LMC Supernova

Three high energy events in the burst observed by Kamiokande II are interpreted to be caused by the arrival of SUSY particles, the photino or the scalar neutrino, with a mass of ~ 30 e V. Shortly after the discovery of the supernova explosion!) (SN1987 A) in the Large Magellanic Cloud (LMC) it was reported 2 ) by th~ Kamiokande II Collaboration that a neutrino burst preceded many hours before the optical brightening. A global feature of the twelve neutrino-like events reported there, their average energy of ~15 MeV, event rate and time span of several seconds, roughly agrees with what is expected 3 ) in a Type II supernova explosion, in which an inner core of about one solar mass (1.4 Me) gravitationally collapses and binding energy of ~ 3 X 10 53 erg is released.

IRAS observations of collisionally heated dust in Large Magellanic Cloud supernova remnants

view Abstract Citations (31) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS IRAS Observations of Collisionally Heated Dust in Large Magellanic Cloud Supernova Remnants Graham, James R. ; Evans, A. ; Albinson, J. S. ; Bode, M. F. ; Meikle, W. P. S. Abstract IRAs additional observations are presented which show that luminous far-infrared sources are associated with the Large Magellanic Cloud supernova remnants N63A, N49, N49B, and N186D. Comparison of the infrared and X-ray data shows that a substantial fraction of the infrared emission from three of the remnants can be accounted for by collisionally heated dust. The ratio of dust-grain cooling to total atomic cooling by lines, recombination, and bremsstrahlung is about 10 in X-ray emitting gas. The evolution of a supernova remnant in a two-phase interstellar medium is considered, and it is concluded that dust cooling will not dominate supernova remnant evolution, but it probably accelerates the process. Publication: The Astrophysical Journal Pub Date: August 1987 DOI: 10.1086/165438 Bibcode: 1987ApJ...319..126G Keywords: Cosmic Dust; Infrared Spectra; Magellanic Clouds; Particle Collisions; Plasma Heating; Supernova Remnants; Far Infrared Radiation; Infrared Astronomy Satellite; Stellar Evolution; Astrophysics; GALAXIES: MAGELLANIC CLOUDS; INFRARED: SOURCES; INTERSTELLAR: GRAINS; NEBULAE: SUPERNOVA REMNANTS; RADIATION MECHANISMS full text sources ADS | data products SIMBAD (9) NED (1)

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.

Possible binary star progenitor for SN1987A

Accurate optical astrometry gives a position (B 1950.0) for the Large Magellanic Cloud supernova, SN1987A, relative to the FK4 system as right ascension, RA = 05 h 35min 49.95 s± 0.039s (0.21″), declination δ −69° 17′ 57.9″ ±0.27″. Differential astrometry carried out on prime-focus plates taken with the Anglo-Australian telescope indicates that the component, star 1, of Sanduleak's star Sk–69202 is within 0.05±0.13arcs of the super-nova. Here we report that this precision astrometry, together with estimates of the probability of a chance association with a fore-ground or background star, lead us to conclude that the progenitor of SN1987A was star 1 or a fainter binary companion.

Upper limit on the mass of the electron neutrino

The historic detection by the Kamiokande-II collaboration1 and the IMB collaboration2 of neutrinos from the Large Magellanic Cloud (LMC) supernova provides the first opportunity to determine the mass, , of the electron neutrino from astronomical observations. Here we show that , is less than 11 eV, provided only that propagation effects have not conspired to sharpen, by more than a factor of two the narrow pulse-width of neutrinos, observed by the Kamiokande-II collaboration from the LMC supernova. This result improves on the laboratory limit on and confirms the view that electron neutrinos do not constitute the major component of the matter density of the Universe.

Discovery of a 50 millisecond pulsar in the Large Magellanic Cloud

The present investigation is concerned with the discovery of a new pulsed X-ray source in the Large Magellanic Cloud (LMC) supernova remnant 0540 - 693. The SNR 0540 - 693 is one of three suspected Crab-like remnants in the LMC. The existing X-ray, optical, and radio observations of the remnant itself are discussed, and an analysis is conducted of the implications of the period, period derivative, and X-ray pulse shape of the new source. It is concluded that the pulsed X-ray source is almost certainly a young, isolated pulsar. Many of its properties are very similar to those of the Crab pulsar.

Optical emission from shock waves. I - Abundances in N49

From models of plane-parallel radiating shock waves and the observations of Osterbrock and Dufour, the abundances of oxygen, nitrogen, neon and sulfur (and indirectly, or carbon) are derived for the Large Magellanic Cloud supernova remnant N49. These are somewhat smaller than solar values, and it is concluded that the discrepancies between these and values derived for the LMC H II regions reflect the composition of ''ice'' grains with low sublimation temperatures which are destroyed in the supernova event. (AIP)