Volume 566, June 2014
|Number of page(s)||18|
|Published online||29 May 2014|
The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards
1 Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, 72076 Tübingen, Germany
2 NASA Goddard Space Flight Center, Greenbelt MD 20771, USA
3 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
Received: 26 February 2014
Accepted: 8 April 2014
Context. In the framework of the Virtual Observatory (VO), the German Astrophysical VO (GAVO) developed the registered service TheoSSA (Theoretical Stellar Spectra Access). It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code, generally for all effective temperatures, surface gravities, and elemental compositions. We will establish a database of SEDs of flux standards that are easily accessible via TheoSSA’s web interface.
Aims. The OB-type subdwarf Feige 110 is a standard star for flux calibration. State-of-the-art non-local thermodynamic equilibrium stellar-atmosphere models that consider opacities of species up to trans-iron elements will be used to provide a reliable synthetic spectrum to compare with observations.
Methods. In case of Feige 110, we demonstrate that the model reproduces not only its overall continuum shape from the far-ultraviolet (FUV) to the optical wavelength range but also the numerous metal lines exhibited in its FUV spectrum.
Results. We present a state-of-the-art spectral analysis of Feige 110. We determined , log g = 6.00 ± 0.20, and the abundances of He, N, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, and Ge. Ti, V, Mn, Co, Zn, and Ge were identified for the first time in this star. Upper abundance limits were derived for C, O, Si, Ca, and Sc.
Conclusions. The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of astronomical data and cross-calibration between different instruments can be based on models and SEDs calculated with state-of-the-art model-atmosphere codes.
Key words: standards / stars: abundances / stars: atmospheres / stars: individual: Feige 110 / subdwarfs / virtual observatory tools
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666.
Table 2, Figs. 3 and 7 are available in electronic form at http://www.aanda.org
© ESO, 2014
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