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Ultraviolet spectroscopy of the blue supergiant SBW1: the remarkably weak wind of a SN 1987A analogue
Smith, Nathan; France, Kevin; Groh, Jose H. +1 more
The Galactic blue supergiant SBW1 with its circumstellar ring nebula represents the best known analogue of the progenitor of SN 1987A. High-resolution imaging has shown Hα and infrared structures arising in an ionized flow that partly fills the ring's interior. To constrain the influence of the stellar wind on this structure, we obtained an ultrav…
Saturn's rings and associated ring plasma cavity: Evidence for slow ring erosion
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +2 more
We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 Rs (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak imp…
Snow carrots after the Chelyabinsk event and model implications for highly porous solar system objects
Luther, Robert; Wünnemann, Kai; Artemieva, Natalia +2 more
After the catastrophic disruption of the Chelyabinsk meteoroid, small fragments formed funnels in the snow layer covering the ground. We constrain the pre-impact characteristics of the fragments by simulating their atmospheric descent with the atmospheric entry model. Fragments resulting from catastrophic breakup may lose about 90% of their initia…
Whistler mode waves upstream of Saturn
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +3 more
Whistler mode waves are generated within and can propagate upstream of collisionless shocks. They are known to play a role in electron thermodynamics/acceleration and, under certain conditions, are markedly observed as wave trains preceding the shock ramp. In this paper, we take advantage of Cassini's presence at 10 AU to explore the importance of…
Diffuse interstellar bands carriers and cometary organic material★
Bertaux, Jean-Loup; Lallement, Rosine
We suggest that the large organic molecules found in the dust of comet 67P/CG originated from the interstellar medium (ISM), and that this material is the source of absorption features in stellar spectra known as diffuse interstellar bands (DIBs). These large organic molecules were present in the ISM prior to the emergence of the pre-solar nebula …
Suzaku analysis of the supernova remnant G306.3-0.9 and the gamma-ray view of its neighbourhood
Sezer, A.; Yamazaki, R.; Ergin, T.
We present an investigation of the supernova remnant (SNR) G306.3-0.9, using archival multiwavelength data. The Suzaku spectra are well described by two-component thermal plasma models: the soft component is in ionization equilibrium and has a temperature ∼0.59 keV, while the hard component has temperature ∼3.2 keV and ionization time-scale ∼2.6 ×…
Stability of Sulphur Dimers (S2) in Cometary Ices
Lunine, J. I.; Mousis, O.; Ronnet, T. +5 more
S2 has been observed for decades in comets, including comet 67P/Churyumov-Gerasimenko. Despite the fact that this molecule appears ubiquitous in these bodies, the nature of its source remains unknown. In this study, we assume that S2 is formed by irradiation (photolysis and/or radiolysis) of S-bearing molecules embedded in th…
The Magnetic Future of the Sun
Metcalfe, Travis S.; Judge, Philip G.; Guinan, Edward +2 more
We analyze space- and ground-based data for the old (7.0 ± 0.3 Gyr) solar analogs 16 Cyg A and B. The stars were observed with the Cosmic Origins UV Spectrographs on the Hubble Space Telescope (HST) on 2015 October 23 and 2016 February 3, respectively, and with the Chandra X-ray Observatory on 2016 February 7. Time-series data in Ca II data are us…
The Polarization Signature of Photospheric Magnetic Fields in 3D MHD Simulations and Observations at Disk Center
Rezaei, R.; Puschmann, K. G.; Beck, C. +1 more
Before using three-dimensional (3D) magnetohydrodynamical (MHD) simulations of the solar photosphere in the determination of elemental abundances, one has to ensure that the correct amount of magnetic flux is present in the simulations. The presence of magnetic flux modifies the thermal structure of the solar photosphere, which affects abundance d…
Integrated cosmological probes: concordance quantified
Amara, Adam; Refregier, Alexandre; Nicola, Andrina
Assessing the consistency of parameter constraints derived from different cosmological probes is an important way to test the validity of the underlying cosmological model. In an earlier work [1], we computed constraints on cosmological parameters for ΛCDM from an integrated analysis of CMB temperature anisotropies and CMB lensing from Planck, gal…