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The Hubble Space Telescope View of LINER Nuclei: Evidence for a Dual Population?
Chiaberge, Marco; Capetti, Alessandro; Macchetto, F. Duccio
We study a complete, distance-limited sample of 25 LINERs, 21 of which have been imaged with the Hubble Space Telescope. In nine objects we detect an unresolved nucleus. To study their physical properties, we compare the radio and optical properties of the nuclei of LINERs with those of other samples of local active galactic nuclei (AGNs), namely,…
First current density measurements in the ring current region using simultaneous multi-spacecraft CLUSTER-FGM data
Balogh, A.; Dandouras, I.; Lucek, E. +7 more
The inner magnetosphere's current mapping is one of the key elements for current loop closure inside the entire magnetosphere. A method for directly computing the current is the multi-spacecraft curlometer technique, which is based on the application of Maxwell-Ampère's law. This requires the use of four-point magnetic field high resolution measur…
The first detection of [OIII] emission from high-redshift damped Lyman-α galaxies
Fall, S. M.; Møller, P.; Weatherley, S. J. +3 more
We present the detection of [OIII] emission lines from the galaxies responsible for two high-redshift z > 1.75 damped Lyman-α (DLA) absorption lines. We find two sources of [OIII] emission corresponding to the z= 1.92 DLA absorber towards the quasar Q2206-1958, and we also detect [OIII] emission from the galaxy responsible for the z= 3.10 DLA a…
Repeated X-Ray Flaring Activity in Sagittarius A*
Grosso, N.; Porquet, D.; Ferrando, P. +5 more
Investigating the spectral and temporal characteristics of the X-rays coming from Sagittarius A* (Sgr A*) is essential to our development of a more complete understanding of the emission mechanisms in this supermassive black hole located at the center of our Galaxy. Several X-ray flares with varying durations and spectral features have already bee…
Oxygen-rich AGB stars with optically thin dust envelopes
Heras, A. M.; Hony, S.
The dust composition and dynamics of the circumstellar envelopes of oxygen-rich AGB stars with low mass-loss rates (5 × 10-8-10-5 M⊙ yr-1) have been investigated. We have analyzed the ISO-SWS spectra of twenty-eight oxygen-rich AGB stars with optically thin shells, and modelled the observations with the …
The Loopy Ultraviolet Line Profiles of RU Lupi: Accretion, Outflows, and Fluorescence
Herczeg, Gregory J.; Valenti, Jeff A.; Brown, Alexander +6 more
We present far-ultraviolet (FUV) spectra of the classical T Tauri star RU Lup covering the 912-1710 Å spectral range, as observed by the Hubble Space Telescope STIS and the Far Ultraviolet Spectroscopic Explorer satellite. We use these spectra, which are rich in emission and absorption lines, to probe both the accreting and outflowing gas. Absorpt…
Pushing the ground-based limit: 14-µmag photometric precision with the definitive Whole Earth Telescope asteroseismic data set for the rapidly oscillating Ap star HR1217
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +43 more
HR1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even- and odd-l modes that are distorted by the presence of a strong, global magnetic field. Several recent theoretical studies have found that within the observable atmospheres of roAp stars the pulsation modes are magneto-acoustic with…
Modeling Complete Distributions with Incomplete Observations: The Velocity Ellipsoid from Hipparcos Data
Hogg, David W.; Johnston, Kathryn V.; Blanton, Michael R. +1 more
An algorithm is developed to model the three-dimensional velocity distribution function of a sample of stars using only measurements of each star's two-dimensional tangential velocity. The algorithm works with ``missing data'': it reconstructs the three-dimensional distribution from data (velocity measurements) that all have one dimension that is …
Discovery of a 105 ms X-Ray Pulsar in Kesteven 79: On the Nature of Compact Central Objects in Supernova Remnants
Gotthelf, E. V.; Halpern, J. P.; Seward, F. D.
We report the discovery of 105 ms X-ray pulsations from the compact central object (CCO) in the supernova remnant Kes 79 using data acquired with the Newton X-Ray Multi-Mirror Mission (XMM-Newton). Two observations of the pulsar taken 6 days apart yield an upper limit on its spin-down rate of P˙<7×10-14 s s-1 and no eviden…
Non-parametric mass reconstruction of A1689 from strong lensing data with the Strong Lensing Analysis Package
Diego, J. M.; Broadhurst, T.; Benítez, N. +3 more
We present the mass distribution in the central area of the cluster A1689 by fitting over 100 multiply lensed images with the non-parametric Strong Lensing Analysis Package. The surface mass distribution is obtained in a robust way, finding a total mass of 0.25 × 1015h-1 Msolar within a 70-arcsec circle radius from…