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Solar Irradiance Variations: From Current Measurements to Long-Term Estimates
Solanki, Sami K.; Krivova, Natalie A.
Variations of solar total and spectral irradiance are prime solar quantities purported to have an influence on the Earth's climate. Quantitative estimates of irradiance over as long a time as possible are needed to judge their effectiveness in forcing the climate. In order to do this reliably, first the measured record must be reproduced and a fee…
Total solar irradiance observations from DIARAD/VIRGO
Dewitte, S.; Crommelynck, D.; Joukoff, A.
The Differential Absolute Radiometer is making measurements of the total solar irradiance as part of the Variability of Irradiance and Gravity Oscillations experiment on the Solar and Heliospheric Observatory. We present the measurements made during its 7.8 years of operation, from 1996 until the present (2003). The aging due to UV exposure of the…
Magnetic Field, Hα, and RHESSI Observations of the 2002 July 23 Gamma-Ray Flare
Krucker, Säm; Wang, Haimin; Yurchyshyn, Vasyl +2 more
In this paper we examine two aspects of the 2002 July 23 gamma-ray flare by using multiwavelength observations. First, the data suggest that the interaction of the erupted field with an overlying large-scale coronal field can explain the offset between the gamma-ray and the hard X-ray sources observed in this event. Second, we pay attention to rap…
Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545
Reig, P.; Negueruela, I.; Fabregat, J. +3 more
We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar
Long-term evolution of FU Orionis objects at infrared wavelengths
Prusti, T.; Csizmadia, Sz.; Ábrahám, P. +3 more
We investigate the brightness evolution of seven FU Orionis systems in the 1-100 µm wavelength range using data from the Infrared Space Observatory (ISO). The ISO measurements were supplemented by 2MASS and MSX observations performed in the same years as the ISO mission (1995-98). The spectral energy distributions (SEDs) based on these data …
Collisional evolution of the asteroid belt
Cheng, Andrew F.
A new synthesis of asteroid collisional evolution is motivated by the question of whether most asteroids larger than ∼1 km size are strengthless gravitational aggregates (rubble piles). NEAR found Eros not to be a rubble pile, but a shattered collisional fragment, with a through-going fracture system, and an average of about 20 m regolith cover. O…
Principles of Seismic Holography for Diagnostics of the Shallow Subphotosphere
Braun, D. C.; Lindsey, Charles
We develop the wave-mechanical formalism for phase-correlation computational seismic holography of the shallow subphotosphere under the plane-parallel approximation and apply it to helioseismic Doppler observations from the Michelson Doppler Imager on the SOHO spacecraft of both the quiet Sun and active regions. We compare holographic signatures c…
Accurate X-Ray Position of the Anomalous X-Ray Pulsar XTE J1810-197 and Identification of Its Likely Infrared Counterpart
Covino, S.; Campana, S.; Mereghetti, S. +13 more
We report the accurate subarcsecond X-ray position of the new anomalous X-ray pulsar (AXP) XTE J1810-197, derived with a Chandra High Resolution Camera Target of Opportunity observation carried out in 2003 November. We also report the discovery of a likely IR counterpart based on a Very Large Telescope (IR band) Target of Opportunity observation c…
Observations and three-dimensional photoionization modelling of the Wolf-Rayet planetary nebula NGC 1501
Rauch, T.; Barlow, M. J.; Zhang, Y. +4 more
Deep optical spectra of the high-excitation planetary nebula NGC 1501 and its W04 central star are presented. A recombination line abundance analysis of the emission-line spectrum of the central star yields He:C:O mass fractions of 0.36:0.48:0.16, similar to those of PG 1159 stars. A detailed empirical analysis of the nebular collisionally excited…
Chandra and XMM-Newton observations of NGC 5253: analysis of the X-ray emission from a dwarf starburst galaxy
Heckman, Timothy M.; Stevens, Ian R.; Strickland, David K. +1 more
We present Chandra and XMM-Newton X-ray data of NGC 5253, a local starbursting dwarf elliptical galaxy, in the early stages of a starburst episode. Contributions to the X-ray emission come from discrete point sources and extended diffuse emission, in the form of what appear to be multiple superbubbles, and smaller bubbles probably associated with …