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Total solar irradiance variations since 1978
Fröhlich, Claus
A composite record of solar total irradiance compiled from measurements made by five independent space-based radiometers since 1978 is the basis for an evaluation of the influence of solar activity on total solar irradiance. An empirical model that parameterizes the combined influences of dark sunspots and bright faculae features on solar irradian…
The Unusual Dynamics of Northern Dark Spots on Neptune
Baines, K. H.; Sromovsky, L. A.; Fry, P. M.
Hubble Space Telescope (HST) and ground-based observations of Neptune from 1991 to 2000 show that Neptune's northern Great Dark Spots (NGDS) remained remarkably stable in latitude and longitudinal drift rate, in marked contrast to the 1989 southern Great Dark Spot (GDS), which moved continuously equatorward during 1989 and dissipated unseen during…
Color Gradients and Surface Brightness Profiles of Galaxies in the Hubble Deep Field-North
Moth, Pimol; Elston, Richard J.
We fit elliptical isophotes to the Hubble Deep Field North WFPC-2 and NICMOS data to study the rest-frame (UV218-U300)0 color profiles and rest-frame B surface brightness profiles of 33 intermediate-redshift galaxies (0.5<=z<=1.2) with I814<25 and 50 high-redshift galaxies (2.0<=z<=3.5) wi…
Relationships between CME's and prominences
van Driel-Gesztelyi, L.; Aulanier, G.; Schmieder, B. +6 more
We have studied the erupting prominences which were associated with coronal mass ejections during a series of campaigns involving both spacecraft and ground-based observatories. The evolution of the physical conditions within the prominences was established from Hα and magnetic field observations. Particular attention ahs been paid to the presence…
Wind and ACE observations during the great flow of 1-4 May 1998: Relation to solar activity and implications for the magnetosphere
Farrugia, C. J.; Mason, G. M.; Matsui, H. +13 more
Using magnetic field, plasma, and energetic particle data from Wind and ACE, we analyze interplanetary features associated with the first strongly geoeffective interval in the rising phase of solar cycle 23, which affected Earth on 1-4 May 1998. As shown by [1999], the configuration consisted of a compound stream made up of an interplanetary coron…
Comparing SWAS and ISO observations of water in outflows
Benedettini, M.; Goldsmith, P. F.; Nisini, B. +3 more
We present a detailed comparison of SWAS and ISO observations of H2O, emission in a sample of outflows. By taking into consideration the different methods used to derive the fractional water abundance, we find that, despite the initial apparent discrepancies, there is satisfactory agreement between ISO and SWAS results for the outflows …
Luminosity-metallicity relation for stars on the lower main sequence
Jimenez, Raul; Flynn, Chris; Kotoneva, Eira
We present a comparison of the predictions of stellar models with the luminosity of the lower main sequence (5.5 < MV < 7.3) using K dwarfs in the Hipparcos catalogue. The parallaxes of our comparison stars are known to better than 15 per cent and metallicities have been recently determined from photometry. A major advantage of ou…
The extended atmosphere and evolution of the RV Tau star, R Scuti
Zijlstra, A. A.; Bedding, T. R.; Yamamura, I. +1 more
We analyze ISO/SWS spectra of the RV Tau star R Scuti. The infrared spectra are dominated by H2O emission bands. The near- and mid-infrared excess is attributed to H2O; the dust contribution is less important. We also identify CO, SiO and CO2 bands. The various molecular emission bands originate from an extended at…
The Massive Stellar Content in the Starburst NGC 3049: A Test for Hot-Star Models
Heckman, Timothy M.; Leitherer, Claus; González Delgado, Rosa M. +1 more
The objective of this work is twofold. First, we seek evidence for or against the depletion of massive stars in metal-rich starbursts. A second, equally important goal is to perform a consistency test of the latest generation of starburst models in such a high-metallicity environment. We have obtained high spatial resolution ultraviolet and optica…
Solar irradiance variability and climate
Fröhlich, C.; Lean, J.
Since November 1978 a complete set of total solar irradiance (TSI) measurements from space is available, yielding a time series of more than 23 years. From measurements made by different space-based radiometers (HF on NIMBUS 7, ACRIM I on SMM, ACRIM II on UARS and VIRGO on SOHO) a composite record of TSI is compiled with an overall precision of or…