Search Publications
Distances, extinctions, and stellar parameters for stars in SkyMapper DR3
Lin, Jane; Casagrande, Luca; Asplund, Martin
We present a Bayesian isochrone fitting machinery to derive distances, extinctions, and stellar parameters (Teff, log g, and $\rm [Fe/H]$) for stars in the SkyMapper data release 3 (DR3) survey. We complement the latter with photometry from Gaia, 2MASS, and AllWISE, in addition to priors on parallaxes and interstellar extinction. We fin…
Quantification of O2 formation during UV photolysis of water ice: H2O and H2O:CO2 ices
Linnartz, H.; Chuang, K. -J.; Fedoseev, G. +4 more
Context. The Rosetta and Giotto missions investigated the composition of the cometary comae of 67P/Churyumov-Gerasimenko and 1P/Halley, respectively. In both cases, a surprisingly large amount of molecular oxygen (O2) was detected and was well correlated with the observed abundances of H2O. Laboratory experiments simulating c…
Development of a cometosheath at comet 67P/Churyumov-Gerasimenko. A case study comparison of Rosetta observations
Nilsson, H.; Goetz, C.; Stenberg Wieser, G. +2 more
Context. The ionosphere of a comet is known to deflect the solar wind through mass loading, but the interaction is dependent on cometary activity. We investigate the details of this process at comet 67P using the Rosetta Ion Composition Analyzer.
Aims: This study aims to compare the interaction of the solar wind and cometary ions during two d…
The SDSS-Gaia View of the Color-Magnitude Relation for Blue Horizontal-branch Stars
Limberg, Guilherme; Rossi, Silvia; Perottoni, Hélio D. +3 more
We present an updated sample of blue horizontal-branch (BHB) stars selected from the photometric and spectroscopic data from Sloan Digital Sky Survey and its associated project Sloan Extension for Galactic Understanding and Exploration (SEGUE). With these data, we selected candidates for A-type stars in the color-color space and then a mixture mod…
Winter Weakening of Titan's Stratospheric Polar Vortices
Toigo, A. D.; Teanby, N. A.; Newman, C. E. +3 more
Polar vortices are a prominent feature in Titan's stratosphere. The Cassini mission has provided a detailed view of the breakdown of the northern polar vortex and formation of the southern vortex, but the mission did not observe the full annual cycle of the evolution of the vortices. Here we use a TitanWRF general circulation model simulation of a…
A multi-instrument investigation of the frequency stability of oscillations above the acoustic cut-off frequency with solar activity
Broomhall, A. -M.; Kiefer, R.; Kosak, K.
Below the acoustic cut-off frequency, oscillations are trapped within the solar interior and become resonant. However, signatures of oscillations persist above the acoustic cut-off frequency, and these travelling waves are known as pseudo-modes. Acoustic oscillation frequencies are known to be correlated with the solar cycle, but the pseudo-mode f…
IGR J18249-3243: a new GeV-emitting FR II and the emerging population of high-energy radio galaxies
Ricci, R.; Wieringa, M. H.; Giroletti, M. +10 more
The advent of new all-sky radio surveys such as the VLA Sky Survey and the Rapid ASKAP Continuum Survey, performed with the latest generation radio telescopes, is opening new possibilities on the classification and study of extragalactic γ-ray sources, specially the underrepresented ones like radio galaxies. In particular, the enhanced sensitivity…
A 3D Physics-Based Particle Model of the Venus Oxygen Corona: Variations With Solar Activity
Combi, Michael R.; Tenishev, Valeriy; Shou, Yinsi +2 more
Due to Venus not having a substantial planetary magnetic field the fast-flowing solar wind plasma can propagate to regions close to the planet. Therefore, thermal atomic oxygen in the thermosphere, hot oxygen in the corona, and the resulting pickup oxygen ions are essential for determining the overall interaction of the planet with plasma of the a…
Ultraviolet spectropolarimetry with Polstar: using Polstar to test magnetospheric mass-loss quenching
Cheung, M. C. M.; Wade, G. A.; Nazé, Y. +17 more
Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. This observatory offers unprecedented capabilities to obtain unique information on the magnetic and plasma properties of the…
Hard X-Ray Flares and Spectral Variability in NGC 4395 ULX1
Bachetti, Matteo; Rana, Vikram; Ghosh, Tanuman
We report the detection of flaring events in NGC 4395 ULX1, a nearby ultraluminous X-ray source (ULX), for the first time, using recent XMM-Newton observations. The flaring episodes are spectrally harder than the steady-emission intervals, resulting in higher fractional variability in the high-energy regime. A thin Keplerian and a slim accretion d…