Search Publications
Neptune's rotational period suggested by the extraordinary stability of two features
Karkoschka, Erich
The interior rotation and motions in giant planets have generally been probed only at radio wavelengths from spacecraft near the planet, except for Jupiter's radio emission detectable from Earth. Here I suggest that Neptune's interior can be indirectly probed at visible wavelength by tracking 10 features that are connected with a stationary latitu…
A2163: Merger events in the hottest Abell galaxy cluster. II. Subcluster accretion with galaxy-gas separation
Arnaud, M.; Pratt, G. W.; Bourdin, H. +7 more
Located at z = 0.203, A2163 is a rich galaxy cluster with an intra-cluster medium (ICM) that exhibits extraordinary properties, including an exceptionally high X-ray luminosity, average temperature, and a powerful and extended radio halo. The irregular and complex morphology of its gas and galaxy structure suggests that this cluster has recently u…
The Extreme Overabundance of Molybdenum in Two Metal-poor Stars
Peterson, Ruth C.
We report determinations of the molybdenum abundances in five mildly to extremely metal-poor turnoff stars using five Mo II lines near 2000 Å. In two of the stars, the abundance of molybdenum is found to be extremely enhanced, as high or higher than the neighboring even-Z elements ruthenium and zirconium. Of the several nucleosynthesis scenarios e…
First results of Herschel-SPIRE observations of Titan
Hartogh, P.; Lellouch, E.; Moreno, R. +4 more
We investigate the composition of Titan's stratosphere from high-resolution submillimetric observations performed with the SPIRE instrument on the Herschel satellite. From the flux density spectrum measured in the 20 - 52 cm-1 interval at an apodized resolution of 0.08 cm-1, we determine the stratospheric abundances of CH
Transient Pc3 wave activity generated by a hot flow anomaly: Cluster, Rosetta, and ground-based observations
Glassmeier, K. -H.; Eastwood, J. P.; Wild, J. A. +6 more
Pc3 pulsations are observed in the magnetosphere with wave periods of 10-45 s. Two distinct populations have been observed; one exhibits a frequency dependence on the solar wind magnetic field strength, whereas the other does not. The first population is explained in terms of a model where the bow shock reflects ions which generate upstream foresh…
The Most Slowly Declining Type Ia Supernova 2001ay
Filippenko, Alexei V.; Kirshner, Robert P.; Matheson, Thomas +28 more
We present optical and near-infrared photometry, as well as ground-based optical spectra and Hubble Space Telescope ultraviolet spectra, of the Type Ia supernova (SN) 2001ay. At maximum light the Si II and Mg II lines indicated expansion velocities of 14,000 km s-1, while Si III and S II showed velocities of 9000 km s-1. Ther…
Validation of community models: 3. Tracing field lines in heliospheric models
MacNeice, Peter; Elliott, Brian; Acebal, Ariel
Forecasting hazardous gradual solar energetic particle (SEP) bursts at Earth requires accurately modeling field line connections between Earth and the locations of coronal or interplanetary shocks that accelerate the particles. We test the accuracy of field lines reconstructed using four different models of the ambient coronal and inner heliospher…
Multiwavelength campaign on Mrk 509. V. Chandra-LETGS observation of the ionized absorber
Kaastra, J. S.; Kriss, G. A.; Arav, N. +11 more
Context. We present here the results of a 180 ks Chandra-LETGS observation as part of a large multi-wavelength campaign on Mrk 509.
Aims: We study the warm absorber in Mrk 509 and use the data from a simultaneous HST-COS observation in order to assess whether the gas responsible for the UV and X-ray absorption are the same.
Methods: We a…
Protostars and Stars in the Coronet Cluster: Age, Evolution, and Cluster Structure
Henning, Thomas; Kainulainen, Jouni; Sicilia-Aguilar, Aurora +1 more
We present new optical spectroscopy with the FLAMES spectrograph at the Very Large Telescope (VLT), near-IR imaging with VLT/HAWK-I, and 870 µm mapping with APEX/LABOCA of the Coronet cluster. The optical data allow us to estimate spectral types, extinction, and the presence of accretion in 6 more M-type members, in addition to the 12 that w…
The Relationship between Vertical and Horizontal Magnetic Fields in the Quiet Sun
Tsuneta, Saku; Ishikawa, Ryohko
Vertical magnetic fields have been known for decades to exist in the internetwork region of the Sun, while the properties of horizontal magnetic fields have only recently been extensively investigated with Hinode. Vertical and horizontal magnetic fields in the internetwork region are considered to be separate entities and have thus far not been in…