High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B

Understanding the sources of instrumental systematic noise is a must to improve the design of future spectrographs. In this study, we alternated observations of the well-suited pair of M-stars GJ 725A+B to delve into the sub-night High Accuracy Radial Velocity Planet Searcher for the Northern hemisp...

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Detalles Bibliográficos
Autores: Berdiñas, Z. M., Amado, Pedro J., Anglada-Escudé, Guillem, Rodríguez-López, Cristina, Barnes, J.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2016
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/383264
Acceso en línea:http://hdl.handle.net/10261/383264
Access Level:acceso abierto
Palabra clave:Instrumentation: spectrographs
Techniques: radial velocities
Stars: individual: GJ 725A
Stars: individual: GJ 725B
Stars: low-mass
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spelling High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+BBerdiñas, Z. M.Amado, Pedro J.Anglada-Escudé, GuillemRodríguez-López, CristinaBarnes, J.Instrumentation: spectrographsTechniques: radial velocitiesStars: individual: GJ 725AStars: individual: GJ 725BStars: low-massUnderstanding the sources of instrumental systematic noise is a must to improve the design of future spectrographs. In this study, we alternated observations of the well-suited pair of M-stars GJ 725A+B to delve into the sub-night High Accuracy Radial Velocity Planet Searcher for the Northern hemisphere (HARPS-N) response. Besides the possible presence of a low-mass planet orbiting GJ 725B, our observations reveal changes in the spectral energy distribution (SED) correlated with measurements of the width of the instrumental line profile and, to a lower degree, with the Doppler measurements. To study the origin of these effects, we searched for correlations among several quantities defined and measured on the spectra and on the acquisition images. We find that the changes in apparent SED are very likely related to flux losses at the fibre input. Further tests indicate that such flux losses do not seriously affect the shape of the instrumental point spread function of HARPS-N, but identify an inefficient fitting of the continuum as the most likely source of the systematic variability observed in the full width at half-maximum. This index, accounting for the HARPS-N cross-correlation profiles width, is often used to decorrelate Doppler time series. We show that the Doppler measurement obtained by a parametric least-squares fitting of the spectrum accounting for continuum variability is insensitive to changes in the slope of the SED, suggesting that forward modelling techniques to measure moments of the line profile are the optimal way to achieve higher accuracy. Remaining residual variability at ~1 m s suggests that for M-stars Doppler surveys the current noise floor still has an instrumental origin. © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.The authors thank E. Sánchez Blanco, M. C. Cárdenas Vázquez, N. Piskunov, F. Pepe, C. Lovis, R. Cosentino, X. Dumusque, D. Staab and C. Haswell for constructive comments and discussions. They also acknowledge funding from AYA2011-30147-C03-01 by MINECO/Spain, FEDER funds/EU, and 2011-FQM-7363 of Junta de Andalucía/Spain (ZMB, PJA and CR-L); ZMB acknowledges support from the UGR/Spain and financial funding from FPI BES-2011-049647 of MINECO/Spain. This study is based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The authors thank the referee T. Böhm for his suggestions that helped improved this paper.Peer reviewedOxford University PressMinisterio de Economía y Competitividad (España)European CommissionJunta de AndalucíaConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2025202520162025info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/383264reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE##PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/MICINN//AYA2011-30147-C03-01info:eu-repo/grantAgreement/MICINN//BES-2011-049647http://dx.doi.org/10.1093/mnras/stw906Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3832642026-05-22T06:33:51Z
dc.title.none.fl_str_mv High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
title High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
spellingShingle High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
Berdiñas, Z. M.
Instrumentation: spectrographs
Techniques: radial velocities
Stars: individual: GJ 725A
Stars: individual: GJ 725B
Stars: low-mass
title_short High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
title_full High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
title_fullStr High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
title_full_unstemmed High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
title_sort High-cadence spectroscopy of M dwarfs - I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
dc.creator.none.fl_str_mv Berdiñas, Z. M.
Amado, Pedro J.
Anglada-Escudé, Guillem
Rodríguez-López, Cristina
Barnes, J.
author Berdiñas, Z. M.
author_facet Berdiñas, Z. M.
Amado, Pedro J.
Anglada-Escudé, Guillem
Rodríguez-López, Cristina
Barnes, J.
author_role author
author2 Amado, Pedro J.
Anglada-Escudé, Guillem
Rodríguez-López, Cristina
Barnes, J.
author2_role author
author
author
author
dc.contributor.none.fl_str_mv Ministerio de Economía y Competitividad (España)
European Commission
Junta de Andalucía
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Instrumentation: spectrographs
Techniques: radial velocities
Stars: individual: GJ 725A
Stars: individual: GJ 725B
Stars: low-mass
topic Instrumentation: spectrographs
Techniques: radial velocities
Stars: individual: GJ 725A
Stars: individual: GJ 725B
Stars: low-mass
description Understanding the sources of instrumental systematic noise is a must to improve the design of future spectrographs. In this study, we alternated observations of the well-suited pair of M-stars GJ 725A+B to delve into the sub-night High Accuracy Radial Velocity Planet Searcher for the Northern hemisphere (HARPS-N) response. Besides the possible presence of a low-mass planet orbiting GJ 725B, our observations reveal changes in the spectral energy distribution (SED) correlated with measurements of the width of the instrumental line profile and, to a lower degree, with the Doppler measurements. To study the origin of these effects, we searched for correlations among several quantities defined and measured on the spectra and on the acquisition images. We find that the changes in apparent SED are very likely related to flux losses at the fibre input. Further tests indicate that such flux losses do not seriously affect the shape of the instrumental point spread function of HARPS-N, but identify an inefficient fitting of the continuum as the most likely source of the systematic variability observed in the full width at half-maximum. This index, accounting for the HARPS-N cross-correlation profiles width, is often used to decorrelate Doppler time series. We show that the Doppler measurement obtained by a parametric least-squares fitting of the spectrum accounting for continuum variability is insensitive to changes in the slope of the SED, suggesting that forward modelling techniques to measure moments of the line profile are the optimal way to achieve higher accuracy. Remaining residual variability at ~1 m s suggests that for M-stars Doppler surveys the current noise floor still has an instrumental origin. © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
publishDate 2016
dc.date.none.fl_str_mv 2016
2025
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/383264
url http://hdl.handle.net/10261/383264
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
#PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/MICINN//AYA2011-30147-C03-01
info:eu-repo/grantAgreement/MICINN//BES-2011-049647
http://dx.doi.org/10.1093/mnras/stw906
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Oxford University Press
publisher.none.fl_str_mv Oxford University Press
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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