Celia Rosa Fierro-Santillán

arXiv2021

Algorithm for removing secondary lines blended with Balmer lines in synthetic spectra of massive stars

In order to measure automatically the equivalent width of the Balmer lines in a database of 40,000 atmosphere models, we have developed a program that mimics the work of an astronomer in terms of identifying and eliminating secondary spectral lines mixed with the Balmer lines. The equivalent widths measured have average errors of 5 percent, which makes them very reliable. As part of the FITspec code, this program improves the automatic adjustment of an atmosphere model to the observed spectrum of a massive star.

astro-ph.SR↗

arXiv2021

Creating and using large grids of pre-calculated model atmospheres for rapid analysis of stellar spectra

We present a database of 45,000 atmospheric models (which will become 80,000 models by the end of the project) with stellar masses between 9 and 120 M$_{\odot}$, covering the region of the OB main sequence and W-R stars in the H-R diagram. The models were calculated using the ABACUS I supercomputer and the stellar atmosphere code CMFGEN. The parameter space has 6 dimensions: the effective temperature $T_{\rm eff}$, the luminosity $L$, the metallicity $Z$, and three stellar wind parameters, namely the exponent $β$, the terminal velocity $V_{\infty}$, and the volume filling factor $F_{cl}$. For each model, we also calculate synthetic spectra in the UV (900-2000 Angstroms), optical (3500-7000 Angstroms), and near IR (10000-30000 Angstroms) regions. To facilitate comparison with observations, the synthetic spectra were rotationally broaden using ROTIN3, by covering $v$ sin $i$ velocities between 10 and 350 km/s with steps of 10 km/s, resulting in a library of 1 575 000 synthetic spectra. In order to demonstrate the benefits of employing the databases of pre-calculated models, we also present the results of the re-analysis of $ε$ Ori by using our grid.

astro-ph.SR↗