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|Title:||High-contrast imaging of Sirius A with VLT/SPHERE: looking for giant planets down to one astronomical unit||Authors:||Vigan, A.
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||454||Issue:||1||First Page:||129||Abstract:||Sirius has always attracted a lot of scientific interest, especially after the discovery of a companion white dwarf at the end of the 19th century. Very early on, the existence of a potential third body was put forward to explain some of the observed properties of the system. We present new coronagraphic observations obtained with VLT/SPHERE (Very Large Telescope/Spectro-Polarimetric High-contrast Exoplanet REsearch) that explore, for the very first time, the innermost regions of the system down to 0.2 arcsec(0.5 au) from Sirius A. Our observations cover the near-infrared from 0.95 to 2.3 μm and they offer the best on-sky contrast ever reached at these angular separations. After detailing the steps of our SPHERE/IRDIFS data analysis, we present a robust method to derive detection limits for multispectral data from high-contrast imagers and spectrographs. In terms of raw performance, we report contrasts of 14.3 mag at 0.2 arcsec, ̃16.3 mag in the 0.4-1.0 arcsec range and down to 19 mag at 3.7 arcsec. In physical units, our observations are sensitive to giant planets down to 11 M<SUB>Jup</SUB> at 0.5 au, 6-7 M<SUB>Jup</SUB> in the 1-2 au range and ̃4 M<SUB>Jup</SUB> at 10 au. Despite the exceptional sensitivity of our observations, we do not report the detection of additional companions around Sirius A. Using a Monte Carlo orbital analysis, we show that we can reject, with about 50 per cent probability, the existence of an 8 M<SUB>Jup</SUB> planet orbiting at 1 au.||Acknowledgments:||Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 60.A-9365 and 60.A-9382. AV and GS acknowledge support in France from the French National Research Agency (ANR) through project grant ANR10-BLANC0504-01. DM acknowledges support from the ‘Progetti Premiali’ funding scheme of the Italian Ministry of Education, University, and Research. DH acknowledges support from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013 Grant Agreement no. 247060) and from the Collaborative Research Centre SFB 881 ‘The Milky Way System’ (subproject A4) of the German Research Foundation (DFG). Model atmospheres have been computed at the Pôle Scientifique de Modélisation Numérique of the École Normale Supérieure de Lyon and at the Gesellschaft für Wissenschaftliche Datenverarbeitung Göttingen in collaboration with the Institut für Astrophysik Göttingen. The authors are extremely grateful to C. Thalmann for kindly providing his published Subaru/IRCS detection limits. They would also like to thank the ESO observers that made their best effort to acquire the data during the SPHERE science verification, and D. Mawet and J. Milli for their explanations on the small sample statistics. Finally, they would like to thank L. Mugnier and N. Védrenne, from ONERA, for the spatial rescaling algorithm detailed in Appendix B .||URI:||http://hdl.handle.net/20.500.12386/23748||URL:||https://academic.oup.com/mnras/article/454/1/129/1126748||ISSN:||0035-8711||DOI:||10.1093/mnras/stv1928||Bibcode ADS:||2015MNRAS.454..129V||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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