Related papers: Element Distributions In The Crab Nebula
We present deep images of a region around the Crab nebula made with the VLA, utilizing new imaging and deconvolution algorithms in a search for a faint radio shell. The existence of a high-velocity, hydrogen-rich envelope has been predicted…
The cosmological origin of carbon, the fourth most abundant element in the Universe, is not well known and matter of heavy debate. We investigate the behavior of C/O to O/H in order to constrain the production mechanism of carbon. We…
Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB…
We have analyzed 16 years of observations dedicated to the Crab (pulsar + nebula) with the INTEGRAL SPI instrument to investigate its polarization properties. We find that the source presents a substantially polarized emission (PF = 24%) in…
Time-resolved polarisation measurements of pulsars offer an unique insight into the geometry of their emission regions. Such measure\ ments provide observational constraints on the different models proposed for the pulsar emission…
Flaring episodes from Crab Nebula have been observed. A new mechanism of emission is explored. Particles in Crab pulsar are accelerated to multiple Tev energies, by some mechanisms, described in the paper and they are the reason of observed…
Deep CCD exposures of the peculiar supernova remnant CTB 80 in the light of major optical lines have been obtained. These images reveal significant shock heated emission in the area of the remnant. The sulfur line image shows emission in…
The abundance stratification in the ejecta of the normal Type Ia supernova 2002bo is derived by fitting a series of spectra obtained at close time intervals. A Monte Carlo code, modified to include abundance stratification, is used to…
We present a homogeneous analysis of the oxygen abundance in five H II regions and eight planetary nebulae (PNe) located at distances lower than 2 kpc and with available spectra of high quality. We find that both the collisionally excited…
Thanks to the use of advanced analysis techniques, the H.E.S.S. imaging Cherenkov telescope array has now reached a sensitivity level allowing the detection of sources with fluxes around 1% of the Crab with a limited observation time (less…
We present ISO LWS observations of the proto-planetary nebula CRL 618, a star evolving very fast to the planetary nebula stage. In addition to the lines of 12CO, 13CO, HCN and HNC, we report on the detection of H2O and OH emission together…
We present a new method to derive oxygen and carbon abundances using the ultraviolet (UV) lines emitted by the gas-phase ionised by massive stars. The method is based on the comparison of the nebular emission-line ratios with those…
The Crab nebula was once considered to be a stable source until strong flares, up to 30 times increase in flux, were observed in the MeV and GeV energy range by the AGILE and Fermi Gamma-ray Observatories. Existing nebula models often…
The Chandra Carina Complex Project (CCCP) has shown that the Carina Nebula displays bright, spatially-complex soft diffuse X-ray emission. Here we `sum up' the CCCP diffuse emission work by comparing the global morphology and spectrum of…
Star-forming and starburst galaxies are considered as one of the viable candidate sources of the high-energy cosmic neutrino background detected in IceCube. We revisit contributions of supernova remnants (SNRs) and hypernova remnants (HNRs)…
A complex event observed in the radio pulses from the Crab pulsar in 1997 included echoes, a dispersive delay, and large changes in intensity. It is shown that these phenomena were due to refraction at the edge of a plasma cloud in the…
Much difficulty has so far prevented the emergence of a consistent scenario for the origin of Type Ib and Ic supernovae (SNe). Here, we follow a heuristic approach by examining the fate of helium stars in the mass range 4 to 12Msun, which…
Observations of the Crab Nebula at 850 micron made with the "Submillimetre Common-User Bolometer Array" (SCUBA) on the James Clerk Maxwell Telescope are presented. A variety of chop-throws and scanning directions was used in these…
Aims. We use the IBIS/ISGRI telescope on-board INTEGRAL to measure the position of the centroid of the 20-200 keV emission from the Crab region. Methods. We find that the astrometry of the IBIS telescope is affected by the temperature of…
The mixed morphology class of supernova remnants (MMSNRs) comprises a substantial fraction of observed remnants and yet there is as yet no consensus on their origin. A clue to their nature is the presence of regions that show X-ray evidence…