相关论文: The Na I D resonance lines in main sequence late-t…

We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of O main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used…

A comprehensive model atom for Fe with more than 3000 energy levels is presented. As a test and first application of this model atom, Fe abundances are determined for the Sun and five stars with well determined stellar parameters and…

With the William Herschel Telescope in La Palma we made IJKs observations of an area of about 40'x30' of the Local Group galaxy Draco. This allows us to describe Draco's late-type stellar population across the whole galaxy at a photometric…

In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the density of the interstellar medium (ISM) is very low, and thus the contamination of the stellar spectrum almost negligible. This allows us to identify many metal lines…

We present an atlas of spectra of O- and B-type stars, obtained with the Short Wavelength Spectrometer (SWS) during the Post-Helium program of the Infrared Space Observatory (ISO). This program is aimed at extending the Morgan & Keenan…

We present late-time ($200-400$ days) near-infrared spectral evolution for the Type Ia supernova SN 2005df. The spectra show numerous strong emission features of [CoII], [CoIII], and [FeII] throughout the $0.8-1.8$\mu m region. As the…

Metals in the photospheres of white dwarfs with Teff between 12,000 and 25,000 K should gravitationally settle out of these atmospheres in 1-2 weeks. Temporal variations in the line strengths of these metals could provide a direct…

Using new spectra of 88 K and M-type subdwarfs, we consider novel methods for assigning their spectral types and take steps toward developing a comprehensive spectral sequence for subdwarf types K3.0 to M6.0. The types are assigned based on…

We analyze the applicability of far-infrared fine-structure lines [CII] 158 micron, [OI] 63 micron and [OIII] 88 micron to reliably trace the star formation rate (SFR) in a sample of low-metallicity dwarf galaxies from the Herschel Dwarf…

Stellar spectra derived from current multiple-object fiber-fed spectroscopic radial-velocity surveys, of the type feasible with, among other examples, AUTOFIB, 2dF, HYDRA, NESSIE, and the Sloan survey, differ significantly from those…

We have evaluated the performance of a fine pitch CdTe Double-sided Strip Detector (CdTe-DSD), which was originally developed for the focal plane detector of a hard X-ray telescope to observe the Sun. The detector has a thickness of 750 um…

We measure spectral features of ~3500 K-selected galaxies at 0.5<z<2.0 from high quality medium-band photometry using a new technique. First, we divide the galaxy sample in 32 subsamples based on the similarities between the full spectral…

From equivalent widths of the SI lines at 8694 A, Israelian & Rebolo (2001) and Takada-Hidai et al. (2002) have derived a surprisingly high sulphur-to-iron ratio ([S/Fe] = 0.5 to 0.7) in six halo stars with [Fe/H] ~ -2.0 suggesting perhaps…

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…

We have collected a large body of NIR (H band), UV (2000 A) and Halpha measurements of late-type galaxies. These are used, jointly with spectral evolutionary synthesis models, to study the initial mass function (IMF) in the mass range m > 2…

We have measured the profiles of the Ca II H and K chromospheric emission lines in 147 main sequence stars of spectral type M5-K7 (0.30-0.55 solar masses) using multiple high resolution spectra obtained during six years with the HIRES…

With our robotic 1.2 m TIGRE telescope, we were able to obtain eight optical spectra with intermediate resolution (R = 20,000) of the Nova V659 Sct during different phases of its outburst. We present a list of the lines found in the Nova…

We investigate statistical equilibrium of neutral and singly-ionized strontium in late-type stellar atmospheres. Particular attention is given to the completeness of the model atom, which includes new energy levels, transition…

We have examined the relationship between rotation and activity in 14 late-type (M6-M7) M dwarfs, using high resolution spectra taken at the Keck Observatory and flux-calibrated spectra from the Sloan Digital Sky Survey. Most are inactive…

We present a study of M dwarfs discovered in a large area, multicolor survey. We employ a combination of morphological and color criteria to select M dwarfs to a limiting magnitude in V of 22, the deepest such ground-based survey for M…