Line-profile variations in radial-velocity measurements - Two alternative indicators for planetary searches
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In this article, the authors introduce two methods to identify false-positive planetary signals in the context of radial-velocity exoplanet searches: the first is the bi-Gaussian cross-correlation function fitting (and monitoring of the parameters derived from it), and the second is the measurement of asymmetry in radial velocity spectral line information content.Abstract:
Aims. We introduce two methods to identify false-positive planetary signals in the context of radial-velocity exoplanet searches. The first is the bi-Gaussian cross-correlation function fitting (and monitoring of the parameters derived from it), and the second is the measurement of asymmetry in radial-velocity spectral line information content, Vasy. We assess the usefulness of each of these methods by comparing their results with those delivered by current indicators. Methods. We make a systematic analysis of the most used common line profile diagnosis, Bisector Inverse Slope and Velocity Span, along with the two proposed ones. We evaluate all these diagnosis methods following a set of well-defined common criteria and using both simulated and real data. We apply them to simulated cross-correlation functions that are created with the program SOAP and which are a ected by the presence of stellar spots. We consider di erent spot properties on stars with di erent rotation profiles and simulate observations as obtained with high-resolution spectrographs. We then apply our methodology to real cross-correlation functions, which are computed from HARPS spectra, for stars with a signal originating in activity (thus spots) and for those with a signal rooted on a planet. Results. We demonstrate that the bi-Gaussian method allows a more precise characterization of the deformation of line profiles than the standard bisector inverse slope. The calculation of the deformation indicator is simpler and its interpretation more straightforward. More importantly, its amplitude can be up to 30% larger than that of the bisector span, allowing the detection of smaller-amplitude correlations with radial-velocity variations. However, a particular parametrization of the bisector inverse slope is shown to be more e cient on high-signal-to-noise data than both the standard bisector and the bi-Gaussian. The results of the Vasy method show that this indicator is more e ective than any of the previous ones, being correlated with the radial-velocity with more significance for signals resulting from a line deformation. Moreover, it provides a qualitative advantage over the bisector, showing significant correlations with RV for active stars for which bisector analysis is inconclusive. Conclusions. We show that the two indicators discussed here should be considered as standard tests to check for the planetary nature of a radial-velocity signal. We encourage the usage of di erent diagnosis as a way of characterizing the often elusive line profile deformations.read more
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The Exoplanet Handbook
TL;DR: In this paper, the authors present an overview of the solar system and its evolution, including the formation and evolution of stars, asteroids, and free-floating planets, as well as their internal and external structures.
Journal ArticleDOI
State of the Field: Extreme Precision Radial Velocities
Debra A. Fischer,Guillem Anglada-Escudé,Pamela Arriagada,Roman V. Baluev,Jacob L. Bean,François Bouchy,Lars A. Buchhave,T. A. Carroll,Abhijit Chakraborty,Justin R. Crepp,Rebekah I. Dawson,Scott A. Diddams,Xavier Dumusque,Jason D. Eastman,Michael Endl,Pedro Figueira,Eric B. Ford,Daniel Foreman-Mackey,Paul Fournier,Gabor Furesz,B. Scott Gaudi,P. C. Gregory,Frank Grundahl,Artie P. Hatzes,Guillaume Hébrard,Enrique Herrero,David W. Hogg,Andrew W. Howard,John Asher Johnson,Paul Jorden,C. Jurgenson,David W. Latham,Greg Laughlin,Thomas J. Loredo,Christophe Lovis,Suvrath Mahadevan,T. M. McCracken,Francesco Pepe,Mario R. Perez,David F. Phillips,Peter Plavchan,Lisa Prato,Andreas Quirrenbach,Ansgar Reiners,Paul Robertson,Nuno C. Santos,David Sawyer,Damien Ségransan,Alessandro Sozzetti,Tilo Steinmetz,Andrew Szentgyorgyi,Stéphane Udry,Jeff A. Valenti,Sharon X. Wang,Robert A. Wittenmyer,Jason T. Wright +55 more
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Journal ArticleDOI
State of the Field: Extreme Precision Radial Velocities*
Debra A. Fischer,Guillem Anglada-Escudé,Guillem Anglada-Escudé,Pamela Arriagada,Roman V. Baluev,Jacob L. Bean,François Bouchy,Lars A. Buchhave,T. A. Carroll,Abhijit Chakraborty,Justin R. Crepp,Rebekah I. Dawson,Scott A. Diddams,Scott A. Diddams,Xavier Dumusque,Jason D. Eastman,Michael Endl,Pedro Figueira,Eric B. Ford,Daniel Foreman-Mackey,Daniel Foreman-Mackey,Paul Fournier,Gábor Fűrész,B. Scott Gaudi,P. C. Gregory,Frank Grundahl,Artie P. Hatzes,Guillaume Hébrard,Guillaume Hébrard,Enrique Herrero,David W. Hogg,Andrew W. Howard,John Asher Johnson,Paul Jorden,C. Jurgenson,David W. Latham,Greg Laughlin,Thomas J. Loredo,Christophe Lovis,Suvrath Mahadevan,T. M. McCracken,Francesco Pepe,Mario R. Perez,David F. Phillips,Peter Plavchan,Lisa Prato,Andreas Quirrenbach,Ansgar Reiners,Paul Robertson,Nuno C. Santos,David Sawyer,Damien Ségransan,Alessandro Sozzetti,Tilo Steinmetz,Andrew Szentgyorgyi,Stéphane Udry,Jeff A. Valenti,Sharon X. Wang,Robert A. Wittenmyer,Robert A. Wittenmyer,Jason T. Wright +60 more
TL;DR: The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of the art Doppler precision and identified the critical path challenges for reaching 10 cm s−1 measurement precision as mentioned in this paper.
Journal ArticleDOI
Spectrum radial velocity analyser (SERVAL) - High-precision radial velocities and two alternative spectral indicators
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TL;DR: In this article, a least-squares fitting algorithm was developed to derive the RVs and additional spectral diagnostics implemented in the SpEctrum Radial Velocity AnaLyser (SERVAL), a publicly available python code.
Journal ArticleDOI
The CARMENES search for exoplanets around M dwarfs - Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
M. Lafarga,Ignasi Ribas,C. Lovis,Manuel Perger,Mathias Zechmeister,F. F. Bauer,Martin Kürster,M. Cortés-Contreras,Juan Carlos Morales,E. Herrero,A. Rosich,D. Baroch,Ansgar Reiners,Jose A. Caballero,Andreas Quirrenbach,Pedro J. Amado,J. M. Alacid,Víctor J. S. Béjar,Víctor J. S. Béjar,Stefan Dreizler,A. P. Hatzes,Th. Henning,S. V. Jeffers,Adrian Kaminski,D. Montes,S. Pedraz,Cristina Rodríguez-López,J. H. M. M. Schmitt +27 more
TL;DR: In this paper, the authors present a methodology to first build weighted binary masks and, second, to compute the CCF of spectral observations with these masks from which they derive radial velocities and activity indicators.
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