D. J. M. Kester

The ISO-SWS post-helium atlas of near-infrared stellar spectra

We present an atlas of near-infrared spectra (2.36m-4.1m) of300 stars at moderate resolution (/ 1500- 2000). The spectra were recorded using the Short-Wavelength Spectrometer aboard the Infrared Space Observatory (ISO-SWS). The bulk of the observations were performed during a dedicated observation campaign after the liquid helium depletion of the ISO satellite, the so-called post-helium programme. This programme was aimed at extending the MK-classification to the near- infrared. Therefore the programme covers a large range of spectral types and luminosity classes. The 2.36m-4.05 mr egion is a valuable spectral probe for both hot and cool stars. H I lines (Bracket, Pfund and Humphreys series), He I and He II lines, atomic lines and molecular lines (CO, H2O, NH, OH, SiO, HCN, C2H2, ...) are sensitive to temperature, gravity and/or the nature of the outer layers of the stellar atmosphere (outflows, hot circumstellar discs, etc.). Another objective of the programme was to construct a homogeneous dataset of near-infrared stellar spectra that can be used for population synthesis studies of galaxies. At near-infrared wavelengths these objects emit the integrated light of all stars in the system. In this paper we present the dataset of post-helium spectra completed with observations obtained during the nominal operations of the ISO-SWS. We discuss the calibration of the SWS data obtained after the liquid helium boil-o and the data reduction. We also give a first qualitative overview of how the spectral features in this wavelength range change with spectral type. The dataset is scrutinised in two papers on the quantitative classification of near-infrared spectra of early-type stars (Lenorzer et al. 2002) and late-type stars (Vandenbussche et al., in prep).

On the analysis of band 3 of the ISO-SWS calibration sources

We analyse ISO–SWSu200901 (

Remote analysis of unprocessed IRAS data

R sim 1500

Operating the ISO-SWS InSb detectors at temperatures above 4 K

)

The Extended Dust Emission Around GK Per

12{-}27.5,mu

On the Nature of M stars with a 60 microns Excess

m (band 3) spectra of the 10 standard calibration stars with the highest flux using synthetic spectra generated from (marcs) atmosphere models. The comparison between the observed and synthetic spectra reveals the quality ofxa0(1) the atmospheric model construction and subsequent synthetic spectra computation and ofxa0(2) the (OLPu200910.1) calibration and data reduction of the spectrometer at these wavelengths.u2029The models represent the general features of the observations, but the synthetic spectrum computation is hampered by the lack of comprehensive molecular and atomic line lists. We also suspect some problems with the temperature distribution in the outer layers of the model and inaccuracies in the extrapolation of the collision-induced absorption coefficients ofxa0H 2 pairs. We detect baseline ripples and fringes in the observed spectra, that survive the calibration and detailed reduction process. Photometric calibration uncertainties are estimated by means of the scaling factors between the synthetic and observed spectra.

The ISO handbook

The Infrared Astronomical Satellite (IRAS) was operated in 1983 to make an all‐sky catalog of point‐like celestial sources. The performance of the satellite, which was much better than specified, combined with 10 years of progress in computer technology and data analysis techniques has made it possible to derive ever improving products from the original data set. Publishing of, or providing access to standard products cannot keep up with the newest developments. This paper describes a service that is able to provide tailored analysis results from the original, unprocessed data, allowing the scientific community to profit immediately from any progress.

A radio continuum and H i study of IC 63, IC 59, and IRAS 00556 + 6048: nebulae in the vicinity of γ Cas

The Short-Wavelength Spectrometer (SWS) is one of the four focal plane instruments of ESAs Infrared Space Observatory (ISO). The satellite was launched on November 15, 1995 with a super fluid Helium content of about 2300 liters to keep the telescope, the scientific payload and the optical baffles at operating temperatures between 2 and 8 K. On April 8, 1998 the liquid Helium depleted and the instruments were switched-off when the focal plane reached a temperature of 4.2 K. A satellite engineering test program was conducted between April 20 and May 10. Timeslots before and during the test program were used to operate the InSb detectors of the SWS instrument while the temperature of the focal plane slowly increased up to 40 K. The instrument was used to record spectra of 260 stars between 2.36 and 4.05 microns at a resolution of 2000 and with high S/N. Goal of the program was to observe a set of stars covering the entire MK spectral classification scheme to extend this classification scheme to the infrared. We discuss changes in the instrument relevant for operating and calibrating the instrument at temperatures above 4K: changes in the InSb detector behavior (dark levels, noise, response, ...), behavior of the JFETs and geometry changes in the grating scanner mechanism. We also show that the calibration of the data obtained after Helium loss is accurate, resulting in a data set of great scientific value.

The ISO Handbook, Volume V - SWS - The Short Wavelength Spectrometer

GK Per, a classical nova system that erupted in 1901, is one of the more unusual examples of its type. It has the longest known orbital period for a classical nova (1.997 d; Crampton, Cowley & Fisher 1986); and it contains a white dwarf primary with an evolved K2 sub-giant secondary. Most remarkably, the IRAS Sky Survey (1991) reveals that GK Per exhibits far-IR dust emission extending ~ 17′ to the NW and SE of the nova (Bode et al. 1987; Seaquist et al. 1989). We have re-analysed the IRAS data using maximum entropy reconstruction (Bontekoe et al. 1991; Bontekoe, Koper & Kester 1994) to resolve structures at a spatial resolution approaching the diffraction limit of IRAS, which is 1′ at 60μm and 1.7′ at 100 μm.

SS 433 extended radio structure observed with the European VLBI Network

Some years ago, Willems & de Jong (1988) noticed that many carbon stars display an excess of emission at 60 pm and explained it by the presence of a fossil dust shell, containing only cold dust. This detached dust shell would be the result of an interruption of the mass loss, consequence of a thermal pulse. Detached shells around C stars have actually been mapped in the CO lines (Olofsson et al. 1992), and at 60pm (Waters et al. 1994). In 1992, Zijlstra et al. found about 100 M stars displaying an excess of emission at 60 /jm, and proposed that interruptions of the mass loss due to thermal pulses is a general phenomenon on the AGB. This assumption is now supported by the theoretical calculations of Vassiliadis & Wood (1993). Here we present a detailed study of the 100 M stars of Zijlstra et al. in order to test the previous assumption.