Search Publications
How Long Is the Day on Saturn?
Sánchez-Lavega, Agustín
Determining a planet's rotation period can be difficult if the planet lacks a solid surface. However, for planets with an internal magnetic field, emissions at radio wavelengths are modulated by the planet's rotation rate. The latest results from the Cassini spacecraft seem to indicate that Saturn's rotation rate has slowed down by 6 minutes since…
Generation of microwave bursts with zebra pattern by nonlinear interaction of Bernstein modes
Kuznetsov, A. A.
The processes of generation and nonlinear interaction of Bernstein modes are investigated. The physical conditions considered correspond here to the sources of microwave bursts with a zebra pattern. It is shown that the simultaneous generation of plasma waves corresponding to several cyclotron harmonics is possible under these conditions. Nonlinea…
BIMA Millimeter-Wave Observations of the Core-Jet and Molecular Gas in the FR I Radio Galaxy NGC 3801
Baum, Stefi A.; O'Dea, Christopher P.; Vogel, Stuart N. +2 more
We present BIMA 3 mm observations of the radio continuum source and the molecular gas disk in the radio-loud Fanaroff and Riley type I (FR I) galaxy NGC 3801. We have detected a continuum source in the nucleus and determined that it has a flat millimeter-wave spectrum, suggesting that the emission is nonthermal and due to an AGN; the radio core is…
High-resolution observations of SN 2001gd in NGC 5033
Lundqvist, P.; Ros, E.; Guerrero, M. A. +8 more
We report on 8.4-GHz very-long-baseline interferometry (VLBI) observations of SN 2001gd in the spiral galaxy NGC 5033 made on 2002 June 26 (2002.48) and 2003 April 8 (2003.27). We used the interferometric visibility data to estimate angular diameter sizes for the supernova by model fitting. Our data nominally suggest a relatively strong decelerati…
Resolving the hard X-ray emission of GX 5-1 with INTEGRAL
Rodriguez, J.; Kuulkers, E.; Paizis, A. +5 more
We present the study of one year of INTEGRAL data on the neutron star low mass X-ray binary GX 5 1. Thanks to the excellent angular resolution and sensitivity of INTEGRAL, we are able to obtain a high quality spectrum of GX 5 1 from ~5 keV to ~100 keV, for the first time without contamination from the nearby black hole candidate GRS 1758-258 above…
X-Ray and Optical Emission from Radio Hot Spots of Powerful Quasars
Maraschi, L.; Cheung, C. C.; Tavecchio, F. +4 more
In a survey with Chandra and HST of a sample of 17 radio sources with bright radio jets (16 powerful FR II and one nearby FR I), we detected X-ray and optical emission from a number of radio hot spots and lobes. Six hot spots on the near sides of powerful FR II galaxies (as determined from the jet asymmetry) were detected at X-rays, while none wer…
XMM-Newton observation of the anomalous X-ray pulsar 4U 0142+61
Wilms, J.; Staubert, R.; Göhler, E.
We present results of an observation of the anomalous X-ray pulsar 4U 0142+61 with the EPIC cameras on XMM-Newton performed on 2003 January 24. The pulse phase averaged spectrum can be best described by the sum of a black body with a temperature of kTBB = 0.395(5) keV and a power law with photon index Γ=3.62(5). The unabsorbed 2-10 keV …
A Cross-Calibration between Tycho-2 Photometry and Hubble Space Telescope Spectrophotometry
Maíz-Apellániz, J.
By analyzing a well-calibrated sample of 256 stars observed with both Hipparcos and HST, I show that Tycho-2 photometry and HST spectrophotometry are accurate and stable enough to obtain a precise cross-calibration. Based on this analysis, I obtain the following photometric zero points with respect to Vega for Tycho-2: 0.020+/-0.001 (BT…
X-Ray Variability Characteristics of the Seyfert 1 Galaxy NGC 3783
Markowitz, A.
We have characterized the energy-dependent X-ray variability properties of the Seyfert 1 galaxy NGC 3783 using archival XMM-Newton and Rossi X-Ray Timing Explorer data. The high-frequency fluctuation power spectral density function (PSD) slope is consistent with flattening toward higher energies. Light-curve cross-correlation functions yield no si…
Low energy electron microsignatures at the orbit of Tethys: Cassini MIMI/LEMMS observations
Livi, S.; Krupp, N.; Woch, J. +10 more
We report on low energy electron microsignature observations by the Low Energy Magnetospheric Measurement System (LEMMS) in the vicinity of Tethys's L-shell, during the first seven orbits of the Cassini mission. Tethys, due to its large size, is the source of strong microsignatures. Shallower absorption features seen are the result of aged Tethys …