IR Spectroscopy of WN Stars

Populations of WC and WN stars in Wolf-Rayet galaxies

We report the detection of WC stars in five WolfRayet (W-R) galaxies: He 2-10, NGC 3049, NGC 3125, NGC 5253 and Tol 89. The faint broad C IV λ5808 line requires sufficiently high S/N (>∼ 40) to be detected explaining the nondetection of this WC feature in previous observations. From the measurement of W-R emission lines (N III λ4640+C III λ4650, He II λ4686, and C IV λ5808), we conclude that al...

WN stars in the LMC: Parameters and atmospheric abundances

The spectra of 18 WN stars in the Large Magellanic Cloud (LMC) are quantitatively analyzed by means of “standard” Wolf-Rayet model atmospheres, using the helium and nitrogen lines as well as the spectral energy distribution. The hydrogen abundance is also determined. Carbon is included for a subset of 4 stars. The studied sample covers all spectral subtypes (WN2... WN9) and also includes one WN...

2 . 4 – 197 μ m spectroscopy of OH / IR stars : the IR characteristics of circumstellar dust in O - rich environments ?

Infrared spectra of a number of evolved O-rich stars have been obtained with the Short-and Long-Wavelength spectrometers on board the Infrared Space Observatory. The very broad wavelength coverage (2.4–197 µm) obtained by combining observations made with the two spectrometers includes practically all of the flux emitted by the sources, and allows us to determine the emission and absorption feat...

Reflectance IR Spectroscopy

Infrared spectroscopy is study of the interaction of radiation with molecular vibrations which can be used for a wide range of sample types either in bulk or in microscopic amounts over a wide range of temperatures and physical states. As was discussed in the previous chapters, an infrared spectrum is commonly obtained by passing infrared radiation through a sample and determining what fraction...

FT-IR Photoacoustic Spectroscopy