Search Publications
Resolving the Stellar Populations in the Circumnuclear Ring of NGC 7469
Colina, L.; Knapen, J. H.; Díaz-Santos, T. +2 more
We investigate the stellar populations in the star-forming ring of the luminous infrared galaxy NGC 7469. We use HST multiwavelength (UV through NIR) imaging complemented with new K-band ground-based long-slit spectroscopy, and mid-IR and radio maps from the literature. SEDs and evolutionary synthesis models have been used to characterize the star…
Validation of Time-Distance Helioseismology by Use of Realistic Simulations of Solar Convection
Zhao, Junwei; Kosovichev, Alexander G.; Georgobiani, Dali +3 more
Recent progress in realistic simulations of solar convection have given us an unprecedented opportunity to evaluate the robustness of solar interior structures and dynamics obtained by methods of local helioseismology. We present results of testing the time-distance method using realistic simulations. By computing acoustic wave propagation time an…
MIDAS The Micro-Imaging Dust Analysis System for the Rosetta Mission
Steller, M.; Alleyne, H. St. C.; Ehrenfreund, P. +22 more
The International Rosetta Mission is set for a rendezvous with Comet 67 P/Churyumov-Gerasimenko in 2014. On its 10 year journey to the comet, the spacecraft will also perform a fly-by of the two asteroids Stein and Lutetia in 2008 and 2010, respectively. The mission goal is to study the origin of comets, the relationship between cometary and inter…
The anatomy of a magnetar: XMM monitoring of the transient anomalous X-ray pulsar XTE J1810–197
Gotthelf, E. V.; Halpern, J. P.
We present the latest results from a multi-epoch timing and spectral study of the Transient Anomalous X-ray Pulsar XTE J1810–197. We have acquired seven observations of this pulsar with the Newton X-ray Multi-mirror Mission (XMM-Newton) over the course of two and a half years, to follow the spectral evolution as the source fades from outburst. The…
Speckle interferometry of nearby multiple stars. IV. Measurements in 2004 and new orbits
Weigelt, G.; Rastegaev, D. A.; Balega, Yu. Yu. +4 more
The results of speckle interferometric observations of 104 binary and 6 triple stars performed at the BTA 6 m telescope in 2004 October are presented. Nearby low-mass stars are mostly observed for the program, among which 59 there are new binaries recently discovered by the Hipparcos astrometric satellite. Concurrently with the diffraction-limited…
Simulating the Cosmos: The Fraction of Merging Galaxies at High Redshift
Taniguchi, Y.; Sargent, M. T.; Capak, P. +7 more
Simulations of nearby (0.015<z<0.025) SDSS galaxies have been used to reproduce as accurately as possible the appearance that they would have on COSMOS ACS images if they had been observed at z~0.7 and ~1.2. These simulations include surface brightness dimming, the effects of bandpass shifting, the changing spatial resolution, and the increa…
Swift X-Ray Observations of Classical Novae
Schmitt, J. H. M. M.; Ness, J. -U.; Gehrels, N. +5 more
The new γ-ray burst (GRB) mission Swift has obtained pointed observations of several classical novae in outburst. We analyzed all the observations of classical novae from the Swift archive up to 2006 June 30. We analyzed usable observations of 12 classical novae and found 4 nondetections, 3 weak sources, and 5 strong sources. This includes detecti…
On the Size of Structures in the Solar Corona
DeForest, C. E.
Fine-scale structure in the corona appears not to be well resolved by current imaging instruments. Assuming this to be true offers a simple geometric explanation for several current puzzles in coronal physics, including the apparent uniform cross section of bright threadlike structures in the corona, the low EUV contrast (long apparent scale heigh…
Elusive AGN in the XMM-Newton bright serendipitous survey
Page, M. J.; Carrera, F. J.; Caccianiga, A. +3 more
Context: Optical follow-up of X-ray selected sources finds a significant fraction of “optically dull” sources characterized by optical spectra without obvious signature of AGN activity. In many cases, however, the presence of an AGN is inferred from other diagnostics (e.g. the X-ray properties). Understanding and accounting for this “elusiveness” …
Interstellar Dust in the Solar System
Altobelli, Nicolas; Krüger, Harald; Grün, Eberhard +1 more
The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse almost perpendicular to the ecliptic plane (inclination 79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. The in situ dust detector on board continuously measured interstellar dust grains with masses up to 10-13 k…