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On the Nature of the Progenitor of the Type Ia SN2011fe in M101
Liu, Jifeng; Wang, Tao; Di Stefano, Rosanne +1 more
The explosion of a Type Ia supernova, SN2011fe, in the nearby Pinwheel galaxy (M101 at 6.4 Mpc) provides an opportunity to study pre-explosion images and search for the progenitor, which should consist of a white dwarf (WD), possibly surrounded by an accretion disk, in orbit with another star. We report on our use of deep Chandra observations and …
Observations of classical and recurrent novae with X-ray gratings
Orio, M.
X-ray grating spectra have opened a new window on nova physics. High signal-to-noise spectra have been obtained for 12 novae after the outburst in the last 13 years, with the Chandra and XMM-Newton gratings. They offer the only way to probe the temperature, effective gravity and chemical composition of the hydrogen burning white dwarf before it tu…
Solar-like oscillations in the G9.5 subgiant β Aquilae
Grundahl, F.; Kjeldsen, H.; Leccia, S. +3 more
Context. An interesting asteroseismic target is the G9.5 IV solar-like star β Aql. This is an ideal target for asteroseismic investigations, because precise astrometric measurements are available from Hipparcos that greatly help in constraining the theoretical interpretation of the results. The star was observed during six nights in August 2009 by…
Radiative transfer analyses of Titan's tropical atmosphere
Tomasko, Martin G.; Griffith, Caitlin A.; Penteado, Paulo F. +2 more
Titan's optical and near-IR spectra result primarily from the scattering of sunlight by haze and its absorption by methane. With a column abundance of 92 km amagat (11 times that of Earth), Titan's atmosphere is optically thick and only ∼10% of the incident solar radiation reaches the surface, compared to 57% on Earth. Such a formidable atmosphere…
Distance to northern high-latitude HI shells
Lallement, R.; Puspitarini, L.
Context. A detailed three-dimensional (3D) distribution of interstellar matter in the solar neighborhood is increasingly necessary. It would allow a more realistic computation of photons and cosmic rays propagation, which is of prime importance for microwave and gamma-ray background emission interpretation, as well as a better understanding of the…
Dust to Dust: Three Years in the Evolution of the Unusual SN 2008S
Garnavich, P. M.; Kochanek, C. S.; Stanek, K. Z. +5 more
We obtained late-time optical and near-IR imaging of SN 2008S with the Large Binocular Telescope, near-IR data with the Hubble Space Telescope, and mid-IR data with the Spitzer Space Telescope. We find that (1) it is again invisible at optical (UBVR) wavelengths to magnitude limits of approximately 25 mag, (2) while detected in the near-IR (H) at …
The hypergiant HR 8752 evolving through the yellow evolutionary void
Meynet, G.; Lobel, A.; Kolka, I. +5 more
Context. We study the time history of the yellow hypergiant HR 8752 based on high-resolution spectra (1973-2005), the observed MK spectral classification data, B - V- and V-observations (1918-1996) and yet earlier V-observations (1840-1918).
Aims: Our local thermal equilibrium analysis of the spectra yields accurate values of the effective te…
Ultraviolet extinction toward a quiescent molecular cloud in the Small Magellanic Cloud
Maíz Apellániz, J.; Rubio, M.
Context. The mean UV extinction law for the Small Magellanic Cloud (SMC) is usually taken as a template for low-metallicity galaxies. However, its current derivation is based on only five stars, which renders its universality questionable. More targets with measured extinction laws in the SMC are necessary to determine its possible dependence on p…
Hundred Thousand Degree Gas in the Virgo Cluster of Galaxies
Manset, N.; Sparks, W. B.; Pringle, J. E. +6 more
The physical relationship between low-excitation gas filaments at ~104 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ~107 K in the centers of many galaxy clusters is not understood. It is unclear whether the ~104 K filaments have cooled and condensed from the ambient hot (~107
Formation of unsaturated hydrocarbons in interstellar ice analogues by cosmic rays
Pilling, S.; da Silveira, E. F.; Rothard, H. +3 more
The formation of C=C and C≡C bonds from the processing of pure c-C6H12 (cyclohexane) and mixed H2O:NH3:c-C6H12 (1:0.3:0.7) ices by highly charged and energetic ions (219-MeV 16O7 + and 632-MeV 58Ni24 +) is studied. The experiments simulate…