2013A&A...557A..93F


C.D.S. - SIMBAD4 rel 1.7 - 2021.06.13CEST07:41:26

2013A&A...557A..93F - Astronomy and Astrophysics, volume 557A, 93-93 (2013/9-1)

Line-profile variations in radial-velocity measurements. Two alternative indicators for planetary searches.

FIGUEIRA P., SANTOS N.C., PEPE F., LOVIS C. and NARDETTO N.

Abstract (from CDS):

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. 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 affected by the presence of stellar spots. We consider different spot properties on stars with different 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. 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 efficient 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 effective 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. 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 different diagnosis as a way of characterizing the often elusive line profile deformations.

Abstract Copyright:

Journal keyword(s): planetary systems - techniques: radial velocities - line: profiles - methods: data analysis

Errata: + corrigendum vol. 582, p. C2 (2015)

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 224789 PM* 00 00 40.3200880868 -69 40 33.476427013   9.12 8.24     K1V 60 0
2 HD 36051 PM* 05 26 42.6222412238 -45 02 58.746128169   8.79 8.22     F7V 36 0
3 BD-21 3153 PM* 10 47 25.3881024407 -22 17 12.171256877   11.049 10.000 9.877   K4.5Vk: 33 0
4 HD 97041 * 11 10 04.9328061278 -22 02 22.681007259   10.233 9.891     F2/3V 5 0
5 HD 103720 BY* 11 56 41.1855718442 -02 46 44.235013734   10.44 9.49     K1IV/V 45 0
6 HD 166435 PM* 18 09 21.3817906855 +29 57 06.165674208   7.457 6.829     G1IV 173 0
7 HD 200143 PM* 21 02 41.2087306360 -34 48 46.551852306   10.65 9.69     G8V 26 0
8 HD 216770 PM* 22 55 53.7082013969 -26 39 31.548008089   8.92 8.10     G9VCN+1 117 1

    Equat.    Gal    SGal    Ecl

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2021.06.13-07:41:26

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