Search Publications
The profiles of the aromatic infrared bands explained with molecular carriers
Joblin, C.; Boissel, P.; Pech, C.
Using a compilation of the photophysical properties of molecules such as coronene, C24H12, we have constructed a numerical model to calculate the IR emission spectrum of a population of polycyclic aromatic hydrocarbon (PAH) species subjected to UV photons. The model enables us to calculate not only the energy emitted in the I…
High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton
Kaastra, J. S.; Raassen, A. J. J.; Mewe, R. +6 more
We report the analysis of the high-resolution soft X-ray spectrum of the nearby F-type star Procyon in the wavelength range from 5 to 175 Å obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra and with the Reflection Grating Spectrometers (RGS) and the EPIC-MOS CCD spectrometers on board XMM-Newton. Line fluxes h…
The blue compact dwarf galaxy I Zw 18: A comparative study of its low-surface-brightness component
Thuan, T. X.; Izotov, Y. I.; Green, R. F. +4 more
Using HST and ground-based optical and NIR imaging data we investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 possesses an extended low-surface-brightness (LSB) old stellar population underlying its star-forming regions, as is the case in the majority of BCDs. This question is central to the long-standing debate on the evolutionary st…
Spectroscopic diagnostics of stellar transition regions and coronae in the XUV: AU Mic in quiescence
Mason, H. E.; Landini, M.; Del Zanna, G.
In this paper we review the spectroscopic diagnostic techniques that can be applied to XUV observations of active stars. In particular, we discuss methods for the determination of electron densities, emission measures and the chemical composition of the stellar transition regions and coronae. We pay particular attention to the atomic data used and…
A study of bright southern slowly pulsating B stars. II. The intrinsic frequencies
Aerts, C.; De Cat, P.
We present the results of detailed frequency analyses of a sample of thirteen confirmed slowly pulsating B stars. Our analysis is based on a combination of elaborate photometric and spectroscopic data-sets. The original sample consists of a mixture of five confirmed slowly pulsating B stars and twelve candidate slowly pulsating B stars discovered …
Rotational velocities of A-type stars. I. Measurement of v sin i in the southern hemisphere
Royer, F.; Gerbaldi, M.; Faraggiana, R. +1 more
Within the scope of a Key Programme determining fundamental parameters of stars observed by HIPPARCOS, spectra of 525 B8 to F2-type stars brighter than V=8 have been collected at ESO. Fourier transforms of several line profiles in the range 4200-4500 Å are used to derive v sin i from the frequency of the first zero. Statistical analysis of the sam…
On the association between type II radio bursts and CMEs
Aurass, H.; Claßen, H. T.
Ground-based observations of metric (coronal) type II radio bursts are compared with observations of coronal mass ejections (CMEs) obtained by the LASCO coronagraph aboard SOHO and with decametric (interplanetary) type II bursts recorded by the WAVES instrument aboard Wind. The basic data sample comprises 63 metric type II radio bursts observed du…
A multi-epoch spectrophotometric atlas of symbiotic stars
Munari, U.; Zwitter, T.
A multi-epoch, absolute-fluxed spectral atlas extending from about 3200 to 9000 Å is presented for 130 symbiotic stars, including members of the LMC, SMC and Draco dwarf galaxies. The fluxes are accurate to better than 5% as shown by comparison with Tycho and ground-based photometric data. The spectra of 40 reference objects (MKK cool giant standa…
Multiplicity among chemically peculiar stars. II. Cool magnetic Ap stars
Babel, J.; Carrier, F.; Udry, S. +1 more
We present new orbits for sixteen Ap spectroscopic binaries, four of which might in fact be Am stars, and give their orbital elements. Four of them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars are: HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 a…
On the intensity contrast of solar photospheric faculae and network elements
Solanki, S. K.; Sanahuja, B.; Ortiz, A. +2 more
Sunspots, faculae and the magnetic network contribute to solar irradiance variations. The contribution due to faculae and the network is of basic importance, but suffers from considerable uncertainty. We determine the contrasts of active region faculae and the network, both as a function of heliocentric angle and magnetogram signal. To achieve thi…