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.

Créditos:

ESO

Sobre a imagem

Id:eso9953b
Tipo:Mapa
Data de divulgação:16 de Dezembro de 1999
Notícias relacionadas:eso9953
Tamanho:764 x 962 px

Sobre o objeto

Nome:NGC 6397
Tipo:Milky Way : Star : Evolutionary Stage : White Dwarf
Milky Way : Star : Grouping : Cluster : Globular
Distância:7000 anos-luz
Categoria:Star Clusters
Stars

Formatos de imagens

JPEG grande
203,2 KB

Cores e filtros

BandaTelescópio
Óptico
B
Very Large Telescope
FORS1