10 research outputs found
Spectangular: Disentangling variable spectra
Spectangular is a GUI based software package written in C++ designed for
spectral disentangling on the wavelength scale. The code disentangles spectra
of SB1 and SB2 systems and can now also be used also for spectra showing
variability. In this work, effects of variability caused by telluric lines,
line profile, and continuum flux are being investigated. Also shown is the
disentangling on spectra from an artificial eclipsing binary. It is now
possible to optimize on the flux ratios of each spectrum, making the
disentangling a technique for extracting photometric information from
spectroscopic observations usually provided by additional photometry.
Furthermore, we make some comments about changes to the code since it was first
published.Comment: accepted to A&
Spectangular – spectral disentangling for detailed chemical analysis of binaries
Disentangling of spectra helps to improve the orbit parameters and allows detailed chemical analysis. Spectangular is a GUI program written
in C++ for spectral disentangling of spectra of SB1 and SB2 systems. It is based on singular value decomposition in the wavelength space
and is coupled to an orbital solution.The results are the component spectra and the orbital parameters
Carbon 12C/13C isotope ratio of alpha Aurigae revised
Context. Capella ({\alpha} Aur) is one of the few binaries in the sky with
two cool giant stars. With spectral types of G8III and G0III, the two
components appear at different but distinct stages in their evolution. The G0
secondary star is a Hertzsprung-gap giant, and the G8 primary star is thought
to be a clump giant. Aims. We present a new measure of the carbon 12 C/ 13 C
isotope ratio of the primary component of Capella using high-resolution R
250 000 spectra obtained with the Potsdam Echelle Polarimetric and
Spectroscopic Instrument (PEPSI) with both the Vatican Advanced Technology
Telescope (VATT) and the Large Binocular Telescope (LBT). Methods.
Signal-to-noise ratios of up to 2 700 were obtained by averaging nightly
spectra. These average spectra were used to disentangle the two binary
components. The isotope ratio was derived with the use of spectrum synthesis
from the CN lines at 8004 {\AA}. Results. We found that the 12 C/ 13 C ratio of
the primary component of Capella is 17.81.9. Our measurement precision is
now primarily limited by the spectral-line data and by the grid-step size of
the model atmospheres rather than the data. The separated spectrum of the
secondary component does not show distinguishable 12 CN and 13 CN lines because
of its v sin i and higher temperature. Conclusions. Our new 12 C/ 13 C value is
significantly lower than the previous value of 274 but now agrees better
with the recent model prediction of 18.8 - 20.7.Comment: accepted to A&A Letters to the Edito
The assembly and alignment of the 4MOST Wide Field Corrector
The 4-metre Multi-Object Spectroscopic Telescope (4MOST) is a fibre-fed multi-object spectrograph for the VISTA telescope at the ESO Paranal Observatory in Chile. The goal of the 4MOST project is to create a general-purpose and highly efficient spectroscopic survey facility for astronomers in the 4MOST consortium and the ESO community. The instrument itself will record 2436 simultaneous spectra over a ∼4.2 square degree field of view and consists of an optical Wide-Field Corrector (WFC), a fibre positioner system based on a tilting spine design, and three spectrographs giving both high and low spectral dispersion. The WFC comprises of 6 lenses grouped into 4 elements, 2 of which are cemented doublets that act as an atmospheric dispersion corrector (ADC). The first lens element is 0.9m in diameter whilst the diameter of the other elements is 0.65m. For the instrument to meet its science goals, each lens needs to be aligned to ∼50µm – a major challenge. This is achieved using contact metrology methods supplemented by pencil beam laser probes. In particular, a novel off-axis laser beam system has been implemented to test the optics’ alignment before and after shipment. This paper details the alignment and assembly methods and presents the latest results on the achieved lens positioning and projected performance of the WF