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Comet C/2012 S1 (ISON) coma composition at ~4 au from HST observations
Mutchler, Max; Muinonen, Karri; Hines, Dean C. +10 more
We analyze the first color and polarization images of Comet ISON (C/2012 S1) taken during two measurement campaigns of the Hubble Space Telescope (HST) on UTC 2013 April 10 and May 8, when the phase angles of Comet ISON were α≈13.7° and 12.2°, respectively. We model the particles in the coma using highly irregular agglomerated debris particles. Ev…
UNIMAP: a generalized least-squares map maker for Herschel data
Elia, Davide; Molinari, Sergio; Pezzuto, Stefano +5 more
The Herschel space telescope hosts two infrared photometers having an unprecedented resolution, sensitivity and dynamic range. The map making, i.e. the formation of sky images from the instruments' data, is critical for the full exploitation of the satellite and is a difficult task, since the readouts are affected by several disturbances, most not…
Atomic Data and Spectral Model for Fe II
Kallman, Timothy R.; Bautista, Manuel A.; Mendoza, Claudio +4 more
We present extensive calculations of radiative transition rates and electron impact collision strengths for Fe ii. The data sets involve 52 levels from the 3d7, 3d64s, and 3{d}54{s}2 configurations. Computations of A-values are carried out with a combination of state-of-the-art multiconfiguration approac…
Leo P: How Many Metals Can a Very Low Mass, Isolated Galaxy Retain?
McQuinn, Kristen B. W.; Cannon, John M.; Skillman, Evan D. +7 more
Leo P is a gas-rich dwarf galaxy with an extremely low gas-phase oxygen abundance (3% solar). The isolated nature of Leo P enables a quantitative measurement of metals lost solely due to star formation feedback. We present an inventory of the oxygen atoms in Leo P based on the gas-phase oxygen abundance measurement, the star formation history (SFH…
Timing of water plume eruptions on Enceladus explained by interior viscosity structure
Nimmo, Francis; Porco, Carolyn; Čadek, Ondřej +3 more
At the south pole of Saturn's icy moon Enceladus, eruptions of water vapour and ice emanate from warm tectonic ridges. Observations in the infrared and visible spectra have shown an orbital modulation of the plume brightness, which suggests that the eruption activity is influenced by tidal forces. However, the observed activity seems to be delayed…
Re-visit of HST FUV Observations of the Hot-Jupiter System HD 209458: No Si III Detection and the Need for COS Transit Observations
Ballester, G. E.; Ben-Jaffel, L.
The discovery of O i atoms and C ii ions in the upper atmosphere of HD 209458b, made with the Hubble Space Telescope Imaging Spectrograph (STIS) using the G140L grating, showed that these heavy species fill an area comparable to the planet’s Roche lobe. The derived ∼10% transit absorption depths require super-thermal processes and/or supersolar ab…
Low Angular Momentum in Clumpy, Turbulent Disk Galaxies
Glazebrook, Karl; Obreschkow, Danail; Abraham, Roberto G. +8 more
We measure the stellar specific angular momentum {j}s={J}s/{M}s in four nearby (z ≈ 0.1) disk galaxies that have stellar masses {M}s near the break {M}s* of the galaxy mass function but look like typical star-forming disks at z ≈ 2 in terms of their low stability (Q ≈ 1), clumpiness…
Vertical profiles of H2O, H2SO4, and sulfuric acid concentration at 45-75 km on Venus
Krasnopolsky, Vladimir A.
A method developed by Krasnopolsky and Pollack (Krasnopolsky, V.A., Pollack, J.B. [1994]. Icarus 109, 58-78) to model vertical profiles of H2O and H2SO4 vapors and sulfuric acid concentration in the Venus cloud layer has been updated with improved thermodynamic parameters for H2O and H2SO…
A Type II Radio Burst without a Coronal Mass Ejection
Cheng, X.; Ding, M. D.; Chen, P. F. +2 more
Type II radio bursts are thought to be a signature of coronal shocks. In this paper, we analyze a short-lived type II burst that started at 07:40 UT on 2011 February 28. By carefully checking white-light images, we find that the type II radio burst is not accompanied by a coronal mass ejection, only by a C2.4 class flare and narrow jet. However, i…
A Light Curve Analysis of Classical Novae: Free-free Emission versus Photospheric Emission
Kato, Mariko; Hachisu, Izumi
We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission, and nova optical light curves follow the universal dec…