Investigation of residual blaze functions in slit-based echelle spectrograph

Škoda, Petr; Šurlan, B.; Tomić, S.

doi:10.1117/12.789284

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…Another approach for normalizing the continuum is to divide by an extracted flat-field calibration source (e.g., Skoda et al 2008), such as a quartz lamp. However, the quartz lamp will also have a black-body curve superimposed on the blaze function.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Echelle Spectra Continuum with Alpha Shapes and Local Regression Fitting

Cisewski

Davis

et al. 2019

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Continuum normalization of echelle spectra is an important data analysis step that is difficult to automate. Polynomial fitting requires a reasonably high order model to follow the steep slope of the blaze function. However, in the presence of deep spectral lines, a high order polynomial fit can result in ripples in the normalized continuum that increase errors in spectral analysis. Here, we present two algorithms for flattening the spectrum continuum. The Alpha-shape Fitting to Spectrum algorithm (AFS) is completely data-driven, using an alpha shape to obtain an initial estimate of the blaze function. The Alpha-shape and Lab Source Fitting to Spectrum algorithm (ALSFS) incorporates a continuum constraint from a lab source reference spectrum for the blaze function estimation. These algorithms are tested on a simulated spectrum, where we demonstrate improved normalization compared to polynomial regression for continuum

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Section: Introductionmentioning

confidence: 99%

Modeling the Echelle Spectra Continuum with Alpha Shapes and Local Regression Fitting

Cisewski

Davis

et al. 2019

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Spectroscopically resolving the Algol triple system

Kolbas

Pavlovski

Southworth

et al. 2015

Mon. Not. R. Astron. Soc.

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Algol (β Persei) is the prototypical semi-detached eclipsing binary and a hierarchical triple system. From 2006 to 2010 we obtained 121 high-resolution and high-S/Néchelle spectra of this object. Spectral disentangling yields the individual spectra of all three stars, and greatly improved elements both the inner and outer orbits. We find masses of M A = 3.39 ± 0.06 M ⊙ , M B = 0.770 ± 0.009 M ⊙ and M C = 1.58 ± 0.09 M ⊙ . The disentangled spectra also give the light ratios between the components in the B and V bands. Atmospheric parameters for the three stars are determined, including detailed elemental abundances for Algol A and Algol C. We find the following effective temperatures: T A = 12 550 ± 120 K, T B = 4900 ± 300 K and T C = 7550 ± 250 K. The projected rotational velocities are v A sin i A = 50.8 ± 0.8 km s −1 , v B sin i B = 62±2 km s −1 and v C sin i C = 12.4±0.6 km s −1 . This is the first measurement of the rotational velocity for Algol B, and confirms that it is synchronous with the orbital motion. The abundance patterns of components A and C are identical to within the measurement errors, and are basically solar. They can be summarised as mean metal abundances: [M/H] A = −0.03 ± 0.08 and [M/H] C = 0.04 ± 0.09. A carbon deficiency is confirmed for Algol A, with tentative indications for a slight overabundance of nitrogen. The ratio of their abundances is (C/N) A = 2.0 ± 0.4, half of the solar value of (C/N) ⊙ = 4.0 ± 0.7. The new results derived in this study, including detailed abundances and metallicities, will enable tight constraints on theoretical evolutionary models for this complex system.

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Investigation of residual blaze functions in slit-based echelle spectrograph

Cited by 2 publications

References 11 publications

Modeling the Echelle Spectra Continuum with Alpha Shapes and Local Regression Fitting

Modeling the Echelle Spectra Continuum with Alpha Shapes and Local Regression Fitting

Spectroscopically resolving the Algol triple system

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