Spectrum of white dwarf stars in NGC 6397
This chart displays the spectra of four White Dwarf stars in globular cluster NGC 6397, obtained with ANTU/FORS1 and identified as such from these data. The spectra were shifted vertically so that they do not overlap. The wavelength is indicated along the abscissa; the intensity along the ordinate. A "standard" spectrum of a White Dwarf star (of spectral type DA - the hydrogen-rich variety) is shown at the top for comparison. Broad absorption lines from hydrogen atoms in the atmosphere are visible. Although the signal-to-noise ratio is quite small, especially for the lower spectra of the fainter stars, they all show the same strong, broad absorption lines as the comparison spectrum. This permits to classify them unambiguously as WD stars. Individual differences, for instance of the widths of the absorption lines, are clearly present and point to different surface gravity and masses.
Crediti:ESO
A proposito dell'immagine
Identificazione: | eso9953b |
Tipo: | Grafico |
Data di pubblicazione: | 16 Dicembre 1999 |
Notizie relative: | eso9953 |
Dimensione: | 764 x 962 px |
A proposito delll'oggetto
Nome: | NGC 6397 |
Tipo: | Milky Way : Star : Evolutionary Stage : White Dwarf Milky Way : Star : Grouping : Cluster : Globular |
Distanza: | 7000 Anni luce |
Categoria: | Star Clusters Stars |
Formati delle immagini
Colori e filtri
Banda | Telescopio |
---|---|
Ottico B | Very Large Telescope FORS1 |