Search Publications
Survey of Saturn Z-mode emission
Gurnett, D. A.; Persoon, A. M.; Wahlund, J. -E. +6 more
Because of the role of Z-mode emission in the diffusive scattering and resonant acceleration of electrons, we conduct a survey of intensity in the Saturn inner magnetosphere. Z mode is primarily observed as "5 kHz" narrowband emission in the lower density regions where the ratio of cyclotron to plasma frequency, fc/fp > 1 …
An Extreme High-velocity Bipolar Outflow in the Pre-planetary Nebula IRAS 08005-2356
Sahai, R.; Patel, N. A.
We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 (I 08005) with an angular resolution of ∼1″-5″, using the Submillimeter Array, in the 12CO J = 2-1, 3-2, 13CO J = 2-1, and SiO J = 5-4 (v = 0) lines. Single-dish observations, using the SMT 10 m, were made in these lines as well as in the CO…
Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A
Koo, Bon-Chul; Lee, Jae-Joon; Moon, Dae-Sik +1 more
We present the results of extinction measurements toward the main ejecta shell of the Cassiopeia A supernova (SN) remnant using the flux ratios between the two near-infrared (NIR) [Fe ii] lines at 1.26 and 1.64 µm. We find a clear correlation between the NIR extinction (E(J-H)) and the radial velocity of ejecta knots, showing that redshifted…
Evolution of the central stars of young planetary nebulae
Zijlstra, A. A.; van Hoof, P. A. M.; Hajduk, M.
Aims: The evolution of central stars of planetary nebulae was so far documented in just a few cases. However, spectra collected a few decades ago may provide a good reference for studying the evolution of central stars using the emission line fluxes of their nebulae. We investigated evolutionary changes of the [O iii] 5007 Å line flux in the …
Magnetic balltracking: Tracking the photospheric magnetic flux
Innes, D. E.; Attie, R.
Context. One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the flux within small-scale magnetic features. These features are routinely observed in the quiet photosphere and were given various names, such as pores, knots, magnetic patches.
Aims: This work presents a new algorithm for tracking the evoluti…
Molecular nitrogen and methane density retrievals from Cassini UVIS dayglow observations of Titan's upper atmosphere
Esposito, Larry W.; Bradley, E. Todd; Ajello, Joseph M. +4 more
We retrieve number densities of molecular nitrogen (N2) and methane (CH4) from Titan's upper atmosphere using the UV dayglow. We use Cassini Ultraviolet Imaging Spectrograph (UVIS) limb observations from 800 to 1300 km of the N I 1493 Å and N II 1085 Å multiplets, both produced directly from photofragmentation of N2
Mid-J CO shock tracing observations of infrared dark clouds. I.
Johnstone, D.; Caselli, P.; Jiménez-Serra, I. +5 more
Infrared dark clouds (IRDCs) are dense, molecular structures in the interstellar medium that can harbour sites of high-mass star formation. IRDCs contain supersonic turbulence, which is expected to generate shocks that locally heat pockets of gas within the clouds. We present observations of the CO J = 8-7, 9-8, and 10-9 transitions, taken with th…
The far-ultraviolet main auroral emission at Jupiter - Part 2: Vertical emission profile
Khurana, K. K.; Badman, S. V.; Bonfond, B. +6 more
The aurorae at Jupiter are made up of many different features associated with a variety of generation mechanisms. The main auroral emission, also known as the main oval, is the most prominent of them as it accounts for approximately half of the total power emitted by the aurorae in the ultraviolet range. The energy of the precipitating electrons i…
Indications of M-dwarf deficits in the halo and thick disk of the Galaxy
Henning, Thomas; Terada, Hiroshi; Usuda, Tomonori +55 more
We compared the number of faint stars detected in deep survey fields with the current stellar distribution model of the Galaxy and found that the detected number in the H band is significantly smaller than the predicted number. This indicates that M-dwarfs, the major component, are fewer in the halo and the thick disk. We used archived data of sev…
Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind-induced magnetospheric compressions and expansions
Coates, A. J.; Dougherty, M. K.; Cowley, S. W. H. +2 more
We examine planetary period oscillations (PPOs) observed in Saturn's magnetospheric magnetic field data from the time of Saturn's equinox in 2009. In particular, we focus on the time period commencing February 2011, when the oscillations started to display sudden and unexpected changes in behavior at ~100-200 day intervals. These were characterize…