Search Publications
Fluxgate magnetometer offset vector determination by the 3D mirror mode method
Dougherty, M. K.; Glassmeier, K. -H.; Volwerk, M. +5 more
Fluxgate magnetometers on-board spacecraft need to be regularly calibrated in flight. In low fields, the most important calibration parameters are the three offset vector components, which represent the magnetometer measurements in vanishing ambient magnetic fields. In case of three-axis stabilized spacecraft, a few methods exist to determine offs…
Quantitative spectroscopy of extreme helium stars Model atmospheres and a non-LTE abundance analysis of BD+10°2179
Butler, K.; Heber, U.; Przybilla, N. +3 more
Extreme helium stars (EHe stars) are hydrogen-deficient supergiants of spectral type A and B. They are believed to result from mergers in double degenerate systems. In this paper, we present a detailed quantitative non-LTE spectral analysis for BD+10°2179, a prototype of this rare class of stars, using UV-Visual Echelle Spectrograph and Fiber-fed …
Extragalactic background light: a measurement at 400 nm using dark cloud shadow*†- I. Low surface brightness spectrophotometry in the area of Lynds 1642
Leinert, Ch.; Väisänen, P.; Lehtinen, K. +2 more
We present the method and observations for the measurement of the Extragalactic Background Light (EBL) utilizing the shadowing effect of a dark cloud. We measure the surface brightness difference between the opaque cloud core and its unobscured surroundings. In the difference the large atmospheric and Zodiacal light components are eliminated and t…
On the possible triple central star system of PN SuWt 2: no ménage à trois at the heart of the Wedding Ring
Jones, David; Boffin, Henri M. J.
SuWt 2 is a planetary nebula consisting of a bright ring-like waist from which protrude faint extended lobes - a morphology believed to be typical of progenitors which have experienced a close-binary evolution. Previous observations of NSV 19992, the star at the projected centre of SuWt 2, have found it to comprise two A-type stars in a 4.9 d ecli…
An analytic method for identifying dynamically formed runaway stars
Perna, Rosalba; Ryu, Taeho; Leigh, Nathan W. C.
In this paper, we study the three-body products (two single stars and a binary) of binary-binary (2+2) scattering interactions. This is done using a combination of analytic methods and numerical simulations of 2+2 scattering interactions, both in isolation and in a homogeneous background potential. We analytically derive a simple formula relating …
The morphological transformation of red sequence galaxies in clusters since z ∼ 1
Demarco, R.; Lidman, C.; Huertas-Company, M. +6 more
The study of galaxy morphology is fundamental to understand the physical processes driving the structural evolution of galaxies. It has long been known that dense environments host high fractions of early-type galaxies and low fractions of late-type galaxies, indicating that the environment affects the structural evolution of galaxies. In this pap…
A flat-spectrum candidate for a track-type high-energy neutrino emission event, the case of blazar PKS 0723-008
Biermann, P. L.; Kun, E.; Gergely, L. Á.
By cross-correlating both the Parkes Catalogue and the Second Planck Catalogue of Compact Sources with the arrival direction of the track-type neutrinos detected by the IceCube Neutrino Observatory, we find the flat-spectrum blazar PKS 0723-008 as a good candidate for the high-energy neutrino event 5 (ID5). Apart from its coordinates matching thos…
Long-term monitoring of comet 67P/Churyumov-Gerasimenko's jets with OSIRIS onboard Rosetta
Jorda, L.; Lamy, P. L.; Lara, L. M. +47 more
We used the OSIRIS camera system onboard the Rosetta spacecraft to monitor jet activity of comet 67P/Churyumov-Gerasimenko. With a monthly cadence, we covered an epoch from 2014 December to 2015 October, thereby including the first equinox and the perihelion passage. Jet features were measured in individual images, which were used to perform a sta…
On the east-west longitudinally asymmetric distribution of solar proton events
Wan, W.; He, H. -Q.
A large data set of 78 solar proton events observed near the Earth's orbit during 1996-2011 is investigated. An east-west longitudinal (azimuthal) asymmetry is found to exist in the distribution of flare sources of solar proton events. With the same longitudinal separation between the flare sources and the magnetic field line footpoint of observer…
Mid-infrared observations of O-type stars: spectral morphology
Bouret, J. -C.; Audard, M.; Lanz, T. +2 more
We present mid-infrared (mid-IR) observations for a sample of 16 O-type stars. The data were acquired with the NASA Spitzer Space Telescope, using the IRS instrument at moderate resolution (R ∼ 600), covering the range of ∼10-37 µm. Our sample includes early, mid and late O supergiants and dwarfs. We explore for the first time their mid-IR s…