Search Publications
Analysis of astrometric catalogues with vector spherical harmonics
Mignard, F.; Klioner, S.
Aims: We compare stellar catalogues with position and proper motion components using a decomposition on a set of orthogonal vector spherical harmonics. We aim to show the theoretical and practical advantages of this technique as a result of invariance properties and the independence of the decomposition from a prior model.
Methods: We de…
Comparative study of CH+ and SH+ absorption lines observed towards distant star-forming regions⋆⋆⋆
Menten, K. M.; Falgarone, E.; Godard, B. +8 more
Aims: The HIFI instrument onboard Herschel has allowed high spectral resolution and sensitive observations of ground-state transitions of three molecular ions: the methylidyne cation CH+, its isotopologue 13CH+, and sulfanylium SH+. Because of their unique chemical properties, a comparative analysis…
A study of deuterated water in the low-mass protostar IRAS 16293-2422
Ceccarelli, C.; Caux, E.; Vastel, C. +6 more
Context. Water is a primordial species in the emergence of life, and comets may have brought a large fraction to Earth to form the oceans. To understand the evolution of water from the first stages of star formation to the formation of planets and comets, the HDO/H2O ratio is a powerful diagnostic.
Aims: Our aim is to determine pre…
The circumstellar disk of AB Aurigae: evidence for envelope accretion at late stages of star formation?
Guilloteau, S.; Dutrey, A.; Piétu, V. +3 more
Aims: The circumstellar disk of AB Aurigae has garnered strong attention owing to the apparent existence of spirals at a relatively young stage and also the asymmetric disk traced in thermal dust emission. However, the physical conditions of the spirals are still not well understood. The origin of the asymmetric thermal emission is unclear. <…
Evaporating very small grains as tracers of the UV radiation field in photo-dissociation regions
Joblin, C.; Pilleri, P.; Montillaud, J. +1 more
Context. In photo-dissociation regions (PDRs), polycyclic aromatic hydrocarbons (PAHs) may be produced by evaporation of very small grains (VSGs) by the impinging UV radiation field from a nearby star.
Aims: We quantitatively investigate the transition zone between evaporating VSGs (eVSGs) and PAHs in several PDRs.
Methods: We studied th…
The Earliest Phases of Star Formation (EPoS): a Herschel key program. The precursors to high-mass stars and clusters
Henning, Th.; Krause, O.; Balog, Z. +14 more
Context. Stars are born deeply embedded in molecular clouds. In the earliest embedded phases, protostars emit the bulk of their radiation in the far-infrared wavelength range, where Herschel is perfectly suited to probe at high angular resolution and dynamic range. In the high-mass regime, the birthplaces of protostars are thought to be in the hig…
Herschel measurements of the D/H and 16O/18O ratios in water in the Oort-cloud comet C/2009 P1 (Garradd)
Küppers, M.; Hartogh, P.; Lellouch, E. +19 more
The D/H ratio in cometary water is believed to be an important indicator of the conditions under which icy planetesimals formed and can provide clues to the contribution of comets to the delivery of water and other volatiles to Earth. Available measurements suggest that there is isotopic diversity in the comet population. The Herschel Space Observ…
Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317
Auvergne, M.; Baudin, F.; Poretti, E. +14 more
Context. OB stars are important building blocks of the Universe, but we have only a limited sample of them well understood enough from an asteroseismological point of view to provide feedback on the current evolutionary models. Our study adds one special case to this sample, with more observational constraints than for most of these stars.
Ai…
Modelling Herschel observations of hot molecular gas emission from embedded low-mass protostars
Wolfire, M. G.; van Dishoeck, E. F.; Bruderer, S. +6 more
Aims: Young stars interact vigorously with their surroundings, as evident from the highly rotationally excited CO (up to Eu/k = 4000 K) and H2O emission (up to 600 K) detected by the Herschel Space Observatory in embedded low-mass protostars. Our aim is to construct a model that reproduces the observations quantitatively…
Herschel images of Fomalhaut. An extrasolar Kuiper belt at the height of its dynamical activity
Ivison, R. J.; Fridlund, M.; Blommaert, J. A. D. L. +33 more
Context. Fomalhaut is a young (2 ± 1 × 108 years), nearby (7.7 pc), 2 M⊙ star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris.
Aims: We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7'' and 36.7'' a…