Double-blind test program for astrometric planet detection with Gaia

Casertano, Stefano; Lattanzi, M. G.; Sozzetti, A.; Spagna, A.; Jancart, Sylvie; Morbidelli, R.; Pannunzio, R.; Pourbaix, D.; Queloz, D.

doi:10.1051/0004-6361:20078997

Cited by 158 publications

(185 citation statements)

References 132 publications

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“…The first astrometrically discovered brown dwarf was announced by Pravdo et al (2005) and to our knowledge is so far still the only substellar object discovered astrometrically. Future space missions such as SIM Planetquest (Unwin et al 2008) and GAIA (Casertano et al 2008) will discover planets and brown dwarfs around nearby stars in large numbers and will dramatically add to our knowledge about extrasolar planets. signature…”

Section: Summary and Discussionmentioning

confidence: 99%

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

Reffert¹,

Quirrenbach²

2011

A&A

107

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Context. The recently completed re-reduction of the Hipparcos data by van Leeuwen (2007a, Astrophysics and Space Science Library, 350) makes it possible to search for the astrometric signatures of planets and brown dwarfs known from radial velocity surveys in the improved Hipparcos intermediate astrometric data. Aims. Our aim is to put more significant constraints on the orbital parameters which cannot be derived from radial velocities alone, i.e. the inclination and the longitude of the ascending node, than was possible before. The determination of the inclination in particular allows to calculate an unambiguous companion mass, rather than the lower mass limit which can be obtained from radial velocity measurements. Methods. We fitted the astrometric orbits of 310 substellar companions around 258 stars, which were all discovered via the radial velocity method, to the Hipparcos intermediate astrometric data provided by van Leeuwen. Results. Even though the astrometric signatures of the companions cannot be detected in most cases, the Hipparcos data still provide lower limits on the inclination for all but 67 of the investigated companions, which translates into upper limits on the masses of the unseen companions. For nine companions the derived upper mass limit lies in the planetary and for 75 companions in the brown dwarf mass regime, proving the substellar nature of those objects. Two of those objects have minimum masses also in the brown dwarf regime and are thus proven to be brown dwarfs. . Of the others, many are either brown dwarfs or very low mass stars. For Eri, we derive a solution which is very similar to the one obtained using Hubble Space Telescope data.

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Section: Summary and Discussionmentioning

confidence: 99%

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

Reffert¹,

Quirrenbach²

2011

A&A

107

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“…On a larger scale, the GAIA satellite (e.g. Lindegren 2010) will advance the field of astrometric detection and characterisation of planetary systems, because of its outstanding measurement precision (Casertano et al 2008). …”

Section: Introductionmentioning

confidence: 99%

Search for brown-dwarf companions of stars

Sahlmann

Ségransan

Queloz

et al. 2010

A&A

Self Cite

214

314

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Context. The frequency of brown-dwarf companions in close orbit around Sun-like stars is low compared to the frequency of planetary and stellar companions. There is presently no comprehensive explanation of this lack of brown-dwarf companions. Aims. By combining the orbital solutions obtained from stellar radial-velocity curves and Hipparcos astrometric measurements, we attempt to determine the orbit inclinations and therefore the masses of the orbiting companions. By determining the masses of potential brown-dwarf companions, we improve our knowledge of the companion mass-function. Methods. The radial-velocity solutions revealing potential brown-dwarf companions are obtained for stars from the CORALIE and HARPS planet-search surveys or from the literature. The best Keplerian fit to our radial-velocity measurements is found using the Levenberg-Marquardt method. The spectroscopic elements of the radial-velocity solution constrain the fit to the intermediate astrometric data of the new Hipparcos reduction. The astrometric solution and the orbit inclination are found using non-linear χ 2 -minimisation on a two-parameter search grid. The statistical confidence of the adopted orbital solution is evaluated based on the distribution-free permutation test. Results. The discovery of nine new brown-dwarf candidates orbiting stars in the CORALIE and HARPS radial-velocity surveys is reported. New CORALIE radial velocities yielding accurate orbits of six previously-known hosts of potential brown-dwarf companions are presented. Including the literature targets, 33 hosts of potential brown-dwarf companions are examined. Employing innovative methods, we use the new reduction of the Hipparcos data to fully characterise the astrometric orbits of six objects, revealing M-dwarf companions of masses between 90 M J and 0.52 M . In addition, the masses of two companions can be restricted to the stellar domain. The companion to HD 137510 is found to be a brown dwarf. At 95% confidence, the companion of HD 190228 is also a brown dwarf. Twenty-three companions remain brown-dwarf candidates. On the basis of the CORALIE planet-search sample, we obtain an upper limit of 0.6% for the frequency of brown-dwarf companions around Sun-like stars. We find that the companion-mass distribution function increases toward the lower end of the brown-dwarf mass range, suggesting that we detect the high-mass tail of the planetary distribution. Conclusions. Our findings agree with the results of previous similar studies and confirm the pronounced paucity of brown-dwarf companions around Sun-like stars. They are affected by the Hipparcos astrometric precision and mission duration, which limits the minimum detectable companion mass, and some of the remaining candidates are probably brown-dwarf companions.

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“…If confirmed, these results would suggest that the discovery space for EPICS at E-ELT overlaps well with those from RV instruments (HARPS at ESO 3.6 m telescope, ESPRESSO at VLT, and especially CODEX at E-ELT) as well as with that of GAIA (Casertano et al 2008). …”

Section: Predicting the Synergies Between Different Techniquesmentioning

confidence: 62%

MESS (multi-purpose exoplanet simulation system)

Bonavita

Chauvin

Desidera

et al. 2012

A&A

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Context. The high number of planet discoveries made in the last years provides a good sample for statistical analysis, leading to some clues on the distributions of planet parameters, such as masses and periods, at least in close proximity to the host star. We likely need to wait for the extremely large telescopes (ELTs) to have an overall view of the extrasolar planetary systems. Those facilities will finally ensure an overlap of the discovery space of direct and indirect techniques, which is desirable to completely understand the nature of the discovered objects, obtaining both orbital parameters and physical characterization. Aims. In this context it would be useful to have a tool that can be used for the interpretation of the present results that are obtained with various observing techniques, and also to predict what the outcomes would be of the future instruments. Methods. For this reason we built MESS: a Monte Carlo simulation code that uses either the results of the statistical analysis of the properties of discovered planets or the results of the planet formation theories to build synthetic planet populations that are fully described in terms of frequency, orbital elements and physical properties. These synthetic planets can then be used to either test the consistency of their properties with the observed ones given different detection techniques (radial velocity, imaging and astrometry) or to predict the expected number of planets for future surveys, as well as to optimize the future multi-technique observations for their characterization down to telluric masses. Results. In addition to the code description, we present here some of its applications to probe the physical and orbital properties of a putative companion within the circumstellar disk of a given star and to test or constrain the orbital distribution properties of a potential planet population around the members of the TW Hydrae association. Finally, we investigated the synergy of future space and ground-based telescopes instrumentation with the predictive mode of the code, to identify the mass-period parameter space that will be probed in future surveys for giant and rocky planets.

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Double-blind test program for astrometric planet detection with Gaia

Cited by 158 publications

References 132 publications

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

Mass constraints on substellar companion candidates from the re-reducedHipparcosintermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs

Search for brown-dwarf companions of stars

MESS (multi-purpose exoplanet simulation system)

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