Search Publications
Generalised model-independent characterisation of strong gravitational lenses. III. Perturbed axisymmetric lenses
Wagner, J.
In galaxy-galaxy strong gravitational lensing, Einstein rings are generated when the lensing galaxy has an axisymmetric lensing potential and the source galaxy is aligned with its symmetry centre along the line of sight. Using a Taylor expansion around the Einstein radius and eliminating the unknown source, I derive a set of analytic equations tha…
The New Horizons and Hubble Space Telescope search for rings, dust, and debris in the Pluto-Charon system
Hamilton, Douglas P.; Olkin, Cathy B.; Stern, S. Alan +11 more
We conducted an extensive search for dust or debris rings in the Pluto-Charon system before, during, and after the New Horizons encounter in July 2015. Methodologies included attempting to detect features by back-scattered light during the approach to Pluto (phase angle α ∼ 15°), in situ detection of impacting particles, a search for stellar occul…
A Cavity of Large Grains in the Disk around the Group II Herbig Ae/Be Star HD 142666
Rubinstein, A. E.; Calvet, N.; Zhang, K. +3 more
Herbig Ae/Be (HAeBe) stars have been classified into Group I or Group II, and were initially thought to be flared and flat disks, respectively. Several Group I sources have been shown to have large gaps, suggesting ongoing planet formation, while no large gaps have been found in the disks of Group II sources. We analyzed the disk around the Group …
Diffuse interstellar bands in the H II region M17. Insights into their relation with the total-to-selective visual extinction RV
Kaper, L.; de Koter, A.; Cox, N. L. J. +1 more
Context. Diffuse interstellar bands (DIBs) are broad absorption features measured in sightlines probing the diffuse interstellar medium. Although large carbon-bearing molecules have been proposed as the carriers producing DIBs, their identity remains unknown. DIBs make an important contribution to the extinction curve; the sightline to the young m…
Circumstellar ammonia in oxygen-rich evolved stars
Menten, K. M.; Greathouse, T. K.; Wyrowski, F. +3 more
Context. The circumstellar ammonia (NH3) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH3 abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry.
Aims: We would like to characterise the spatial distribution and excita…
SPHERE view of Wolf-Rayet 104. Direct detection of the Pinwheel and the link with the nearby star
Avenhaus, H.; Matter, A.; Lopez, B. +16 more
Context. WR104 is an emblematic dusty Wolf-Rayet star and the prototypical member of a sub-group hosting spirals that are mainly observable with high-angular resolution techniques. Previous aperture masking observations showed that WR104 is likely to be an interacting binary star at the end of its life. However, several aspects of the system are s…
Accurate Ground-based Near-Earth-Asteroid Astrometry Using Synthetic Tracking
Preston, Robert A.; Lazio, Joseph; Zhai, Chengxing +13 more
Accurate astrometry is crucial for determining orbits of near-Earth-asteroids (NEAs) and therefore better tracking them. This paper reports on a demonstration of 10 mas level astrometric precision on a dozen NEAs using the Pomona College 40 inch telescope, at the JPL’s Table Mountain Facility. We used the technique of synthetic tracking (ST), in w…
The Star-grazing Bodies in the HD 172555 System
Roberge, Aki; Brown, Alexander; Grady, C. A. +3 more
Kiefer et al. reported the detection of infalling Ca II absorption in HD 172555, a member of the β Pictoris Moving Group (βPMG). We obtained HST Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph spectroscopy of this star at 2 epochs separated by a week, and we report the discovery of infalling gas in resonant transitions of Si I…
The spiral potential of the Milky Way
Carraro, G.; Grosbøl, P.
Context. The location of young sources in the Galaxy suggests a four-armed spiral structure, whereas tangential points of spiral arms observed in the integrated light at infrared and radio wavelengths indicate that only two arms are massive.
Aims: Variable extinction in the Galactic plane and high light-to-mass ratios of young sources make it…
Investigating a population of infrared-bright gamma-ray burst host galaxies
Stanway, Elizabeth R.; Davies, Luke J. M.; Chrimes, Ashley A. +3 more
We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ∼0.5. This methodology has already identified the host galaxy of …