Presentation Open Access

Extremely precise HARPS-N solar RV to overcome the challenge of stellar signal

X. Dumusque


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  <identifier identifierType="DOI">10.5281/zenodo.5596351</identifier>
  <creators>
    <creator>
      <creatorName>X. Dumusque</creatorName>
      <affiliation>Department of Astronomy of the University of Geneva</affiliation>
    </creator>
  </creators>
  <titles>
    <title>Extremely precise HARPS-N solar RV to overcome the challenge of stellar signal</title>
  </titles>
  <publisher>Zenodo</publisher>
  <publicationYear>2021</publicationYear>
  <subjects>
    <subject>exoplanets; solar radial velocity; stellar activity</subject>
  </subjects>
  <dates>
    <date dateType="Issued">2021-10-25</date>
  </dates>
  <language>en</language>
  <resourceType resourceTypeGeneral="Text">Presentation</resourceType>
  <alternateIdentifiers>
    <alternateIdentifier alternateIdentifierType="url">https://zenodo.org/record/5596351</alternateIdentifier>
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  <relatedIdentifiers>
    <relatedIdentifier relatedIdentifierType="DOI" relationType="IsVersionOf">10.5281/zenodo.5596350</relatedIdentifier>
    <relatedIdentifier relatedIdentifierType="URL" relationType="IsPartOf">https://zenodo.org/communities/plato2021</relatedIdentifier>
  </relatedIdentifiers>
  <rightsList>
    <rights rightsURI="https://creativecommons.org/licenses/by/4.0/legalcode">Creative Commons Attribution 4.0 International</rights>
    <rights rightsURI="info:eu-repo/semantics/openAccess">Open Access</rights>
  </rightsList>
  <descriptions>
    <description descriptionType="Abstract">&lt;p&gt;Detecting and measuring the masses of&amp;nbsp;Earth-like&amp;nbsp;planets in the presence of stellar signals is the main challenge when using the radial-velocity (RV) technique. Even in the&amp;nbsp;&lt;em&gt;PLATO&lt;/em&gt;&amp;nbsp;era where&amp;nbsp;the satellite will provide the period of Earth-like&amp;nbsp;planetary&amp;nbsp;candidates,&amp;nbsp;measuring precisely their mass, which is critical to&amp;nbsp;1) confirm those candidates, 2)&amp;nbsp;constrain further planetary composition and thus planetary formation&amp;nbsp;and 3)&amp;nbsp;constrain further&amp;nbsp;planetary atmospheres,&amp;nbsp;will be extremely&amp;nbsp;challenging.&lt;/p&gt;

&lt;p&gt;&amp;nbsp;&lt;/p&gt;

&lt;p&gt;Critical to a better understanding of RV variations induced by stellar signals and finding correction techniques is RV data with a sampling&amp;nbsp;and SNR&amp;nbsp;sufficient to probe&amp;nbsp;stellar signals&amp;nbsp;ranging from minutes to years. To address this challenge,&amp;nbsp;we can use the unprecedented data from the&amp;nbsp;solar telescope that feed sunlight into HARPS-N, which allows us to obtain Sun-as-a-star RVs at a sub-m/s precision.&lt;/p&gt;

&lt;p&gt;&amp;nbsp;&lt;/p&gt;

&lt;p&gt;In this talk, I will discuss how to reduce properly the HARPS-N solar data to reach a precision of about 50 cm/s on the short and long-term. This implies optimizing the wavelength solution recipe, carefully selecting the most stable thorium lines, but also compensating for the ageing of thorium-argon lamps inducing a drift of thorium lines with time. I will show how those optimizations improve the quality of the data, and therefore will advise any team working in extremely precise RV to perform similar upgrades.&lt;/p&gt;

&lt;p&gt;&amp;nbsp;&lt;/p&gt;

&lt;p&gt;The obtained solar data, published last October, have already been used in several studies that demonstrate that analyzing the HARPS-N solar&amp;nbsp;spectral (or cross-correlation functions) time-series using machine learning algorithms can mitigate stellar signals down to a level where Earth-like planets in the habitable zone could be detected (30 cm/s in semi-amplitude, signal three times larger than Earth).&lt;/p&gt;</description>
  </descriptions>
  <fundingReferences>
    <fundingReference>
      <funderName>European Commission</funderName>
      <funderIdentifier funderIdentifierType="Crossref Funder ID">10.13039/100010661</funderIdentifier>
      <awardNumber awardURI="info:eu-repo/grantAgreement/EC/Horizon 2020 Framework Programme - European Research Council - Starting Grant/851555/">851555</awardNumber>
      <awardTitle>Signal Correction to Reveal other Earths</awardTitle>
    </fundingReference>
  </fundingReferences>
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