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Calibrating the α parameter of convective efficiency using observed stellar properties
Wang, L.; Zhao, G.; Grupp, F. +3 more
Context. Synthetic model atmosphere calculations are still the most commonly used tool when determining precise stellar parameters and stellar chemical compositions. Besides three-dimensional models that consistently solve for hydrodynamic processes, one-dimensional models that use an approximation for convective energy transport play the major ro…
The HIFI spectral survey of AFGL 2591 (CHESS). III. Chemical structure of the protostellar envelope
van der Tak, F. F. S.; van der Wiel, M. H. D.; Semenov, D. A. +2 more
Aims: The aim of this work is to understand the richness of chemical species observed in the isolated high-mass envelope of AFGL 2591, a prototypical object for studying massive star formation.
Methods: Based on HIFI and JCMT data, the molecular abundances of species found in the protostellar envelope of AFGL 2591 were derived with a Mon…
Hubble Space Telescope ultraviolet spectroscopy of the hottest known helium-rich pre-white dwarf KPD 0005+5106
Rauch, T.; Werner, K.
We present a model-atmosphere analysis of the ultraviolet echelle spectra of KPD 0005+5106 taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The star is the hottest known pre-white dwarf (Teff = 200 000 ± 20 000 K, log g= 6.7 ± 0.3 (cm/s2)). Its atmosphere is composed of helium with trace …
Search for hydrogen peroxide in the Martian atmosphere by the Planetary Fourier Spectrometer onboard Mars Express
Aoki, Shohei; Kasaba, Yasumasa; Formisano, Vittorio +4 more
We searched for hydrogen peroxide (H2O2) in the Martian atmosphere using data measured by the Planetary Fourier Spectrometer (PFS) onboard Mars Express during five martian years (MY27-31). It is well known that H2O2 plays a key role in the oxidizing capacity of the Martian atmosphere. However, only a few…
Influence of local ionization on ionospheric densities in Titan's upper atmosphere
Galand, Marina; Coates, Andrew J.; Vigren, Erik +6 more
Titan has the most chemically complex ionosphere of the solar system. The main sources of ions on the dayside are ionization by EUV solar radiation and on the nightside include ionization by precipitated electrons from Saturn's magnetosphere and transport of ions from the dayside, but many questions remain open. How well do models predict local io…
A statistical analysis of current helicity and twist in solar active regions over the phases of the solar cycle using the spectro-polarimeter data of Hinode
Sakurai, Takashi; Otsuji, Kenichi; Kuzanyan, Kirill
Current helicity and twist of solar magnetic fields are important in characterizing the dynamo mechanism working in the convection zone of the Sun. We have carried out a statistical study on the current helicity of solar active regions observed with the spectro-polarimeter (SP) of the Hinode Solar Optical Telescope (SOT). We used SOT-SP data of 55…
A Search for Intergalactic Globular Clusters in the Local Group
di Tullio Zinn, Graziella; Zinn, Robert
The whole Sloan Digital Sky Survey (SDSS, 14,555 {{deg }2}) has been searched for intergalactic globular clusters (IGCs) in the Local Group (LG). Using optical, infrared, and ultraviolet photometric selection criteria and photometric redshifts, the 2.1× {{10}8} objects in the SDSS Galaxy Catalog were reduced to only 183,791 b…
Plasma Physical Parameters along CME-driven Shocks. II. Observation-Simulation Comparison
Bemporad, A.; Susino, R.; Lapenta, G. +1 more
In this work, we compare the spatial distribution of the plasma parameters along the 1999 June 11 coronal mass ejection (CME)-driven shock front with the results obtained from a CME-like event simulated with the FLIPMHD3D code, based on the FLIP-MHD particle-in-cell method. The observational data are retrieved from the combination of white-light c…
Herschel Dust Emission as a Probe of Starless Cores Mass: MCLD 123.5+24.9 of the Polaris Flare
Ferland, Gary J.; Abel, Nicholas P.; Wagle, Gururaj A. +1 more
We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of column densities, and hence masses of molecular cores from Herschel data. We first consider several detailed gr…
The millimeter-wavelength sulfur dioxide absorption spectra measured under simulated Venus conditions
Bellotti, Amadeo; Steffes, Paul G.
Over 130 laboratory measurements of the 2-4 mm wavelength opacity of sulfur dioxide in a carbon dioxide atmosphere under simulated conditions for the upper Venus troposphere (temperatures between 308 and 343 K and pressures between 0.03 and 2 bar) have been made. These measurements along with the centimeter wavelength measurements by Steffes et al…