The Nitrogen Abundance in Be Stars Determined from UV Spectra

Metallicity and Alpha-element Abundance Measurement in Red Giant Stars from Medium Resolution Spectra

We present a technique that applies spectral synthesis to medium resolution spectroscopy (MRS, R ∼ 6000) in the red (6300 Å < λ < 9100 Å) to measure [Fe/H] and [α/Fe] of individual red giant stars over a wide metallicity range. We apply our technique to 264 red giant stars in seven Galactic globular clusters and demonstrate that it reproduces the metallicities and α enhancements derived from hi...

Chemical abundances of β Cephei stars from low - and high - resolution UV spectra

We determined stellar parameters (Teff , [m/H], θ) and E(B− V ) for all β Cephei stars observed during the IUE satellite mission. All parameters were derived by using an algorithmic procedure of fitting theoretical flux distribution (Kurucz 1996) to the IUE observations.

Can Sodium Abundances of A - Type Stars Be Reliably Determined from Na I 5890 / 5896 Lines ? ∗

An extensive non-LTE abundance analysis based on Na i 5890/5896 doublet lines was carried out for a large unbiased sample of ∼ 120 A-type main-sequence stars (including 23 Hyades stars) covering a wide ve sin i range of ∼ 10–300 km s, with an aim to examine whether the Na abundances in such A dwarfs can be reliably established from these strong Na i D lines. The resulting abundances ([Na/H]58),...

Study of the ratios UV-A/UV-B from UV irradiance spectra

The UV - visible emission spectra of oxygen and nitrogen in solid hydrogen and deuterium hosts

Spectra in the wavelength range of 3~ nm have been acquired during proton-beam irradiation of samples of solid hydrogen and deuterium at 4.2 K. Emission spectra from the transitions A I 3Au~X3l:; of O2, 4s-2D ofN I, and ID-IS of 0 I have been measured and attributed to an air impurity in the sample. Comparison is made of the vibrational constants derived from the molecular bands, the spectral s...