Search Publications
Radial Evolution of a Magnetic Cloud: MESSENGER, STEREO, and Venus Express Observations
Forsyth, R. J.; Zurbuchen, T. H.; Raines, J. M. +3 more
The Solar Orbiter and Solar Probe Plus missions will provide observations of magnetic clouds closer to the Sun than ever before, and it will be good preparation for these missions to make full use of the most recent in situ data sets from the inner heliosphere—namely, those provided by MErcury Surface, Space ENvironment, GEochemistry, and Ranging …
Evolution of the plasma environment of comet 67P from spacecraft potential measurements by the Rosetta Langmuir probe instrument
André, M.; Carr, C.; Edberg, N. J. T. +6 more
We study the evolution of the plasma environment of comet 67P using measurements of the spacecraft potential from early September 2014 (heliocentric distance 3.5 AU) to late March 2015 (2.1 AU) obtained by the Langmuir probe instrument. The low collision rate keeps the electron temperature high (∼5 eV), resulting in a negative spacecraft potential…
Does the obscured AGN fraction really depend on luminosity?
Krivonos, R.; Sazonov, S.; Churazov, E.
We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstra…
Measuring star formation with resolved observations: the test case of M 33
Buat, V.; Boquien, M.; Braine, J. +15 more
Context. Measuring star formation on a local scale is important to constrain star formation laws. It is not clear yet, however, whether and how the measure of star formation is affected by the spatial scale at which a galaxy is observed.
Aims: We wish to understand the impact of the resolution on the determination of the spatially resolved st…
Herschel Survey of the Palomar-Green QSOs at Low Redshift
Ho, Luis C.; Scoville, Nicholas Z.; Petric, Andreea O. +1 more
We investigate the global cold dust properties of 85 nearby (z≤slant 0.5) QSOs, chosen from the Palomar-Green sample of optically luminous quasars. We determine their infrared spectral energy distributions and estimate their rest-frame luminosities by combining Herschel data from 70 to 500 µm with near-infrared and mid-infrared measurements …
Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express
Lundin, R.; Bertaux, J. -L.; Gérard, J. -C. +4 more
The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO2+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detectio…
An Optically Obscured AGN in a Low Mass, Irregular Dwarf Galaxy: A Multi-Wavelength Analysis of J1329+3234
Secrest, N. J.; Fischer, J.; Satyapal, S. +6 more
Supermassive black holes (SMBHs) are found ubiquitously in large, bulge-dominated galaxies throughout the local universe, yet little is known about their presence and properties in bulgeless and low-mass galaxies. This is a significant deficiency, since the mass distribution and occupation fraction of nonstellar black holes provide important obser…
Cloud Structure of the Nearest Brown Dwarfs. II. High-amplitude Variability for Luhman 16 A and B in and out of the 0.99 µm FeH feature
Apai, Dániel; Crossfield, Ian J. M.; Radigan, Jacqueline +4 more
The re-emergence of the 0.99 µm FeH feature in brown dwarfs of early- to mid-T spectral type has been suggested as evidence for cloud disruption where flux from deep, hot regions below the Fe cloud deck can emerge. The same mechanism could account for color changes at the L/T transition and photometric variability. We present the first obser…
A Comprehensive Study of Broad Absorption Line Quasars. I. Prevalence of HeI* Absorption Line Multiplets in Low-ionization Objects
Yuan, Weimin; Shu, Xinwen; Zhou, Hongyan +13 more
Neutral helium multiplets, He i* λ λ 3189,3889,10830, are very useful diagnostics for the geometry and physical conditions of the absorbing gas in quasars. So far only a handful of He i* detections have been reported. Using a newly developed method, we detected the He i*λ 3889 absorption line in 101 sources of a well-defined sample of 285 Mg ii br…
The spatially-resolved star formation history of the M31 outer disc
Lewis, Geraint F.; McConnachie, Alan W.; Ibata, Rodrigo A. +4 more
We present deep Hubble Space Telescope Advanced Camera for Surveys observations of the stellar populations in two fields lying at 20 and 23 kpc from the centre of M31 along the south-west semimajor axis. These data enable the construction of colour-magnitude diagrams reaching the oldest main-sequence turn-offs (∼13 Gyr) which, when combined with a…