Search Publications
Progress in sunspot helioseismology
Birch, A. C.
Local helioseismology is a set of methods that are used to study wave propagation and infer physical conditions in the solar interior. Sunspots are a particularly challenging target for local helioseismology. In this review, I will show that some new methods (magnetoconvection simulations and numerical wave propagation simulations) lead to shallow…
Jupiter's Decametric and Hectometric Radio Emissions Observed by Cassini RPWS and Voyager PRA
Imai, K.; Lecacheux, A.; Imai, M. +2 more
The relationship between Jupiter's decametric (DAM) and hectometric (HOM) radio emissions is important to help understand the emission mechanism that both of them have in common, but it has remained an elusive enigma. We have investigated Jovian DAM and HOM emissions observed by the Cassini, Voyager 1 and Voyager 2 spacecraft. We made a statistica…
Statistical properties of the GALEX spectroscopic stellar sample
Chavez, Miguel; Bertone, Emanuele
The GALEX General Data Release 4/5 includes 174 spectroscopic tiles, obtained from slitless grism observations, for a total of more than 60 000 ultraviolet spectra. We have determined statistical properties of the sample of GALEX stars. We have defined a suitable system of spectroscopic indices, which measure the main mid-UV features at the GALEX …
The Dirt on Dry Mergers
Dey, Arjun; Soifer, B. T.; Desai, Vandana +2 more
Using data from the Spitzer Space Telescope, we analyze the mid-infrared (3-70 µm) spectral energy distributions of dry merger candidates in the Boötes field of the NOAO Deep Wide-Field Survey. These candidates were selected by previous authors to be luminous, red, early-type galaxies with morphological evidence of recent tidal interactions.…
XMM-Newton, Swift, and ROSAT Observations of LBQS 0102-2713
Schady, P.; Boller, Th.; Heftrich, T.
We have analyzed the first XMM-Newton, Swift, and archival ROSAT PSPC observations of the quasar LBQS 0102-2713. The object was selected from the ROSAT archive as being notable due to the steep soft X-ray photon index and due to the UV brightness based on Hubble Space Telescope and optical spectroscopic observations. The first XMM-Newton observati…
Specular refection at a non-stationary shock: A simple model
Lucek, E. A.; Mazelle, C.; Wilber, M. +4 more
Analytic treatments of a particle encountering a collisionless shock have commonly been based on the assumption that the shock surface is quasi-planar with length scales larger than the particle gyroradius. Within this framework, the particle distribution function width is supposed to be conserved in any shock reflection process. It is well known,…
Differential Rotation of Strong Magnetic Flux During Solar Cycles 21 - 23
Feng, X. S.; Song, W. B.; Shen, F. +1 more
In the present investigation we measure the differential rotation of strong magnetic flux during solar cycles 21 - 23 with the method of wavelet transforms. We find that the cycle-averaged synodic rotation rate of strong magnetic flux can be written as ω=13.47−2.58sin 2θ or ω=13.45−2.06sin 2θ−1.37sin 4θ, where θ is…
Photometric parameters, distance and period-colour study of contact binary stars in the globular cluster ω Centauri
Sriram, K.; Vivekananda Rao, P.; Kiron, Y. Ravi
We present V passband photometric solutions of six contact binaries in the globular cluster ω Centauri using the Wilson-Devinney code. We found that four of the systems are H subtype W UMa binary systems and remaining two are W-subtype W UMa systems. Four of the systems show the O'Connell effect in their light curves and brightness at 0.75 phase i…
The jet of the BL Lacertae object PKS 2201+044: MAD near-IR adaptive optics observations and comparison with optical, radio and X-ray data
Moretti, A.; Falomo, R.; Treves, A. +14 more
Context. Relativistic jets are a common feature of radio loud active galactic nuclei. Multifrequency observations are a unique tool to constrain their physics.
Aims: We report on a detailed study of the properties of the jet of the nearby BL Lac object PKS 2201+044, one of the rare cases where the jet is detected from radio to X-rays.
Me…
The first GRB survey of the IBIS/PICsIT archive
Mereghetti, S.; Foschini, L.; Di Cocco, G. +6 more
Context. The multi-purpose INTEGRAL mission is continuously contributing to Gamma Ray Burst (GRB) science, thanks to the performances of its two main instruments, IBIS and SPI, operating in the hard X-ray / soft γ-ray domain.
Aims: We investigate the possibilities offered to the study of GRBs by PICsIT, the high-energy detector of the IBIS in…