F. F. Bauer
University of Göttingen
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Featured researches published by F. F. Bauer.
Astronomy and Astrophysics | 2015
F. F. Bauer; M. Zechmeister; Ansgar Reiners
Over the past decades hollow-cathode lamps have been calibration standards for spectroscopic measurements. Advancing to cm/s radial velocity precisions with the next generation of instruments requires more suitable calibration sources with more lines and less dynamic range problems. Fabry-Perot interferometers provide a regular and dense grid of lines and homogeneous amplitudes making them good candidates for next generation calibrators. We investigate the usefulness of Fabry-Perot etalons in wavelength calibration, present an algorithm to incorporate the etalon spectrum in the wavelength solution and examine potential problems. The quasi periodic pattern of Fabry-Perot lines is used along with a hollow-cathode lamp to anchor the numerous spectral features on an absolute scale. We test our method with the HARPS spectrograph and compare our wavelength solution to the one derived from a laser frequency comb. The combined hollow-cathode lamp/etalon calibration overcomes large distortion (50 m/s) in the wavelength solution of the HARPS data reduction software. Direct comparison to the laser frequency comb bears differences of only maximum 10 m/s. Combining hollow-cathode lamps with Fabry-Perot Interferometers can lead to substantial improvements in the wavelength calibration of echelle spectrographs. Etalons can provide economical alternatives to the laser frequency comb, especially for smaller projects.
Astronomy and Astrophysics | 2018
M. Zechmeister; Ansgar Reiners; P. J. Amado; M. Azzaro; F. F. Bauer; V. J. S. Béjar; J. A. Caballero; Eike W. Guenther; H.-J. Hagen; S. V. Jeffers; A. Kaminski; M. Kürster; R. Launhardt; D. Montes; Jérémy Morales; A. Quirrenbach; Sabine Reffert; Ignasi Ribas; W. Seifert; L. Tal-Or; V. Wolthoff
Context: The CARMENES survey is a high-precision radial velocity (RV) programme that aims to detect Earth-like planets orbiting low-mass stars. Aims: We develop least-squares fitting algorithms to derive the RVs and additional spectral diagnostics implemented in the SpEctrum Radial Velocity Analyser (SERVAL), a publicly available python code. Methods: We measured the RVs using high signal-to-noise templates created by coadding all available spectra of each star.We define the chromatic index as the RV gradient as a function of wavelength with the RVs measured in the echelle orders. Additionally, we computed the differential line width by correlating the fit residuals with the second derivative of the template to track variations in the stellar line width. Results: Using HARPS data, our SERVAL code achieves a RV precision at the level of 1m/s. Applying the chromatic index to CARMENES data of the active star YZ CMi, we identify apparent RV variations induced by stellar activity. The differential line width is found to be an alternative indicator to the commonly used full width half maximum. Conclusions: We find that at the red optical wavelengths (700--900 nm) obtained by the visual channel of CARMENES, the chromatic index is an excellent tool to investigate stellar active regions and to identify and perhaps even correct for activity-induced RV variations.
Astronomy and Astrophysics | 2016
Ansgar Reiners; U. Lemke; F. F. Bauer; Benjamin Beeck; Philipp Huke
On March 20, 2015, we obtained 159 spectra of the Sun as a star with the solar telescope and the FTS at the Institut fur Astrophysik Gottingen, 76 spectra were taken during partial solar eclipse. We obtained RVs using
Astronomy and Astrophysics | 2018
S. V. Jeffers; P. Schöfer; A. Lamert; Ansgar Reiners; D. Montes; J. A. Caballero; M. Cortés-Contreras; C. J. Marvin; V. M. Passegger; M. Zechmeister; A. Quirrenbach; F. J. Alonso-Floriano; P. J. Amado; F. F. Bauer; E. Casal; E. Diez Alonso; E. Herrero; J. C. Morales; Reinhard Mundt; Ignasi Ribas; L. F. Sarmiento
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Modeling, Systems Engineering, and Project Management for Astronomy VIII | 2018
Marcelo Said Tala Pinto; Anantha Chanumolu; A. Quirrenbach; Sabine Reffert; M. Zechmeister; F. F. Bauer
as wavelength reference and determined the RM curve with a peak-to-peak amplitude of almost 1.4 km s
Astronomy and Astrophysics | 2018
L. F. Sarmiento; Ansgar Reiners; Philipp Huke; F. F. Bauer; E. W. Guenter; U. Seemann; U. Wolter
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Astronomy and Astrophysics | 2018
L. Tal-Or; M. Zechmeister; Ansgar Reiners; S. V. Jeffers; P. Schöfer; A. Quirrenbach; P. J. Amado; Ignasi Ribas; J. A. Caballero; J. Aceituno; F. F. Bauer; V. J. S. Béjar; S. Czesla; S. Dreizler; B. Fuhrmeister; A. Hatzes; E. N. Johnson; M. Kürster; M. Lafarga; D. Montes; Jérémy Morales; Sabine Reffert; S. Sadegi; W. Seifert; D. Shulyak
at typical RV precision better than 1 m s
Astronomy and Astrophysics | 1995
F. F. Bauer; Dirk Husfeld
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Astronomy and Astrophysics | 2018
F. F. Bauer; Ansgar Reiners; Benjamin Beeck; S. V. Jeffers
. We modeled disk-integrated solar RVs using surface velocities, limb darkening, and information about convective blueshift from 3D magneto-hydrodynamic simulations. We confirm that convective blueshift is crucial to understand solar RVs during eclipse. Our best model reproduced the observations to within a relative precision of 10% with residuals less than 30 m s