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.

Crédit:

ESO

À propos de l'image

Identification:eso9953b
Type:Graphique
Date de publication:16 décembre 1999
Communiqués de presse en rapport:eso9953
Taille:764 x 962 px

À propos de l'objet

Nom:NGC 6397
Type:Milky Way : Star : Evolutionary Stage : White Dwarf
Milky Way : Star : Grouping : Cluster : Globular
Distance:7000 années lumière
Catégorie:Star Clusters
Stars

Image Formats

Grand JPEG
203,2 Kio
JPEG taille écran
260,3 Kio

Couleurs & filtres

DomaineTélescope
Visible
B
Very Large Telescope
FORS1