Page 34 - analysis-and-interpretation-of-astronomical-sp

Analysis and Interpretation of Astronomical Spectra 34

Hβ

Kr(λI) ε Ori, Alnilam B0 Iab HHαα

Hβ I / Ic = I / Ic

Ps(λ)

α Cma, Sirius A1V

ζ Leo, Adhafera F0 III
Sun G2V

Consequences and benefits of a radiometric profile correction with a synthetic continuum

 This procedure provides not a true correction of the attenuation influences
, , . With the direct transformation of the intensity profile from
to , the pseudo continuum is just scaled up to the level of the synthetic and

therefore unreddened model star, and not to the original profile of the observed

ject . Thus, the attenuating effects are simply bypassed here and just a “synthetic”,

rough approximation to the original profile is reached this way. Therefore fluctua-

tions of the continuum radiation cannot be measured in such a profile.

 Since complies now very roughly to the original profile , also the relative in-

tensities of the absorption lines correspond approximately with those in the original

profile. For emission lines , generated independently from the continuum, this applies

just as a rough approximation (sect. 8.8).

 The original relative relationship between two absorption-intensities and ,

which are measured directly and independently of the continuum level, can be estimated

here {7i}, {7j}. For emission line intensities and this applies just as a rough

approximation.

 However it must generally be kept in mind that between different stars, even of the very
same spectral class, considerable differences in the continuum course may occur. This
effect can be significantly enhanced by a strongly different metallicity and/or rotation ve-
locity ( s ). This method does not yet allow any calibration of the intensity axis in
physical units!