Related papers: The flat bottomed lines of Vega
We present high-quality HST/GHRS spectra in the Hydrogen L alpha spectral region of Vega and Sirius-A. Thanks to the signal-to-noise ratio achieved in these observations and to the similarity of the two spectra, we found clear evidence of…
We show that the UV spectrum (1280-3200 A) of the "superficially normal" A-star Vega, as observed by the IUE satellite at a resolution comparable to the star's rotational broadening width, can be fit remarkably well by a single-temperature…
UV, optical, and near-IR spectra of Vega have been combined to test our understanding of stellar atmospheric opacities, and to examine the possibility of constraining chemical abundances from low-resolution UV fluxes. We have carried out a…
The identifications of Fe VII emission lines in the wavelength range 193-197 {\AA} are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra…
We report the detection of a magnetic field on Vega through spectropolarimetric observations. We acquired 257 Stokes V, high signal-to-noise and high-resolution echelle spectra during four consecutive nights with the NARVAL…
In the near ultraviolet (NUV) part of the solar spectrum, there are several Fe I lines with very broad profiles, typical of chromospheric lines. These lines are largely unexplored due to the lack of high-resolution data in this region. This…
The center-to-limb variations (CLVs) of photospheric and chromospheric spectral lines were obtained in 2025 July and August using drift scans from the echelle spectrograph of the 0.7 m Vacuum Tower Telescope at the Observatorio del Teide…
Neutral Fe lines are the most abundant in the spectrum of late stars. They are used to obtain different basic stellar parameters such as relative abundances, surface gravity, and effective temperature. However, the centers of many of these…
We present measurements of the Fe-K line for nine Seyfert I galaxies using Chandra High Energy Transmission Grating Spectrometer (HETGS) data. The centroid energies are narrowly dispersed (6.403 +/- 0.062 keV) and indicate an origin of the…
A bright, nearby edge-on starburst galaxy NGC 253 was studied using the Suzaku, XMM and Chandra X-ray observatories. We detected with Suzaku and XMM complex line structure of Fe K, which is resolved into three lines (Fe I at 6.4 keV, Fe XXV…
We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K' band at projected baselines between 103m and 273m. The measured visibility amplitudes beyond the first lobe are…
The Space Telescope Imaging Spectrograph has measured the absolute flux for Vega from 0.17-1.01 microns on the HST White Dwarf flux scale. These data are saturated by up to a factor of 80 overexposure but retain linearity to a precision of…
A detailed study of emission lines from Fe VII, Fe VIII and Fe IX observed by the EUV Imaging Spectrometer on board the Hinode satellite is presented. Spectra in the ranges 170-212 A and 246-292 A show strongly enhanced lines from the upper…
Wavelengths of absorption lines in the spectra of galaxies along the line-of-sight to distant quasars can be used to probe the variablility of the fine structure constant, $\alpha$, at high redshifts, provided that the laboratory…
The atomic spectra and structure of the open d- and f-shell elements are extremely complex, where tens of thousands of transitions between fine structure energy levels can be observed as spectral lines across the infrared and UV per…
The theoretically studied impact of rapid rotation on stellar evolution needs to be confronted with the results of high resolution spectroscopy-velocimetry observations. A weak surface magnetic field had recently been detected in the A0…
We extend the study of the core of the Fe K$\alpha$ emission line at \sim 6.4 keV in Seyfert galaxies reported in Yaqoob & Padmanabhan (2004) using a larger sample observed by the Chandra High Energy Grating (HEG). Whilst heavily obscured…
We present a comprehensive analysis of the far UV spectrum of G191-B2B over the range of 900-1700{\AA} using co-added data from the FUSE and STIS archives. While previous identifications made by Holberg et al. (2003) are reaffirmed in this…
We have surveyed molecular line emission from Orion BN/KL from 42.3 to 43.6 GHz with the Green Bank Telescope. Sixty-seven lines were identified and ascribed to 13 different molecular species. The spectrum at 7 mm is dominated by SiO, SO2,…
New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions…