Astrometric detection of exoplanets from the ground

Lazorenko, P. F.; Mérand, A.; Queloz, D.; Ségransan, D.; Woillez, J.

doi:10.1117/12.2023929

Cited by 6 publications

(5 citation statements)

References 61 publications

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“…In Fig. 6, the juvenile binary DE0823−49 (L1.5, Sahlmann et al 2014c) appears slightly overluminous. The seemingly overluminous object is DE1733−16 (L1), which is probably caused by blending with a background source in this extremely dense starfield.…”

Section: Discussionmentioning

confidence: 94%

“…The spectrum was reduced using the ESO pipeline in standard setup. We measured the radial velocity on the UVES spectrum using strong atomic lines (Rb  and Cs ) with the method described in Sahlmann et al (2014c) and determined a heliocentric radial velocity of −13.0 ± 1.1 km s −1 . Notes.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…The project is described in Sahlmann et al (2014b), and its first result, the discovery of a low-mass companion to an L dwarf, is reported in Sahlmann et al (2013) and updated by Sahlmann et al (2014c). Details on the astrometric reduction methods are given in Lazorenko et al (2014).…”

Section: Introductionmentioning

confidence: 99%

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Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2015

A&A

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Using astrometric measurements obtained with the FORS2/VLT camera, we are searching for low-mass companions around 20 nearby ultracool dwarfs. With a single-measurement precision of ∼0.1 milli-arcsec, our survey is sensitive to a wide range of companion masses from planetary companions to binary systems. Here, we report the discovery and orbit characterisation of a new ultracool binary at a distance of 19.5 pc from Earth that is composed of the M8.5-dwarf primary DE0630−18 and a substellar companion. The nearly edge-on orbit is moderately eccentric (e = 0.23) with an orbital period of 1120 d, which corresponds to a relative separation in semimajor axis of approximately 1.1 AU. We obtained a high-resolution optical spectrum with UVES/VLT and measured the system's heliocentric radial velocity. The spectrum does not exhibit lithium absorption at 670.8 nm, indicating that the system is not extremely young. A preliminary estimate of the binary's physical parameters tells us that it is composed of a primary at the stellar-substellar limit and a massive brown-dwarf companion. DE0630−18 is a new very low-mass binary system with a well-characterised orbit.

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Section: Discussionmentioning

confidence: 94%

Section: Observations and Data Reductionmentioning

confidence: 99%

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Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2015

A&A

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“…Surveys of small samples indicate that the occurrence of compact UCD binaries is significant (Blake et al 2010;Bardalez Gagliuffi et al 2014;Sahlmann et al 2014b) and that many of those systems have photocentre orbit amplitudes in the range of mas. It has therefore been predicted that Gaia astrometry will eventually characterize hundreds of UCD binary orbits (Sahlmann et al 2014a) and significantly improve our knowledge on the occurrence and properties of compact UCD binaries.…”

Section: Ultracool Dwarf Binariesmentioning

confidence: 99%

GaiaData Release 3

Arenou¹,

Babusiaux²,

Barstow³

2023

A&A

126

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Context. The Gaia DR3 Catalogue contains for the first time about eight hundred thousand solutions with either orbital elements or trend parameters for astrometric, spectroscopic and eclipsing binaries, and combinations of them. Aims. This paper aims to illustrate the huge potential of this large non-single star catalogue. Methods. Using the orbital solutions together with models of the binaries, a catalogue of tens of thousands of stellar masses, or lower limits, partly together with consistent flux ratios, has been built. Properties concerning the completeness of the binary catalogues are discussed, statistical features of the orbital elements are explained and a comparison with other catalogues is performed. Results. Illustrative applications are proposed for binaries across the H-R diagram. The binarity is studied in the RGB/AGB and a search for genuine SB1 among long-period variables is performed. The discovery of new EL CVn systems illustrates the potential of combining variability and binarity catalogues. Potential compact object companions are presented, mainly white dwarf companions or double degenerates, but one candidate neutron star is also presented. Towards the bottom of the main sequence, the orbits of previously-suspected binary ultracool dwarfs are determined and new candidate binaries are discovered. The long awaited contribution of Gaia to the analysis of the substellar regime shows the brown dwarf desert around solar-type stars using true, rather than minimum, masses, and provides new important constraints on the occurrence rates of substellar companions to M dwarfs. Several dozen new exoplanets are proposed, including two with validated orbital solutions and one super-Jupiter orbiting a white dwarf, all being candidates requiring confirmation. Beside binarity, higher order multiple systems are also found. Conclusions. By increasing by more than one order of magnitude the number of known binary orbits, Gaia DR3 will provide, beside a rich reservoir of dynamical masses, an important contribution to the analysis of stellar multiplicity.

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“…On the ground, the main practical limitation is turbulence in the Earth's atmosphere (Sahlmann et al 2013a), which can be overcome with the use of large-aperture telescopes, interferometry, or adaptive optics.…”

Section: Introductionmentioning

confidence: 99%

Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2014

A&A

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Aims. We describe the astrometric reduction of images obtained with the FORS2/VLT camera in the framework of an astrometric planet search around 20 M/L-transition dwarfs. We present the correction of systematic errors, the achieved astrometric performance, and a new astrometric catalogue containing the faint reference stars in 20 fields located close to the Galactic plane. Methods. Remote reference stars were used both to determine the astrometric trajectories of the nearby planet search targets and to identify and correct systematic errors. Results. We detected three types of systematic errors in the FORS2 astrometry: the relative motion of the camera's two CCD chips, errors that are correlated in space, and an error contribution of as yet unexplained origin. The relative CCD motion probably has a thermal origin and typically is 0.001-0.010 px (∼0.1-1 mas), but sometimes amounts to 0.02-0.05 px (3-6 mas). This instability and space-correlated errors are detected and mitigated using reference stars. The third component of unknown origin has an amplitude of 0.03-0.14 mas and is independent of the observing conditions. We find that a consecutive sequence of 32 images of a well-exposed star over 40 min at 0.6 seeing results in a median rms of the epoch residuals of 0.126 mas. Overall, the epoch residuals are distributed according to a normal law with a χ 2 value near unity. We compiled a catalogue of 12 000 stars with I-band magnitudes of 16-22 located in 20 fields, each covering ∼2 × 2 . It contains I-band magnitudes, ICRF positions with 40-70 mas precision, and relative proper motions and absolute trigonometric parallaxes with a precision of 0.1 mas/yr and 0.1 mas at the bright end, respectively. Conclusions. This work shows that an astrometric accuracy of ∼100 micro-arcseconds over two years can be achieved with a large optical telescope in a survey covering several targets and varying observing conditions.

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Astrometric detection of exoplanets from the ground

Cited by 6 publications

References 61 publications

Astrometric planet search around southern ultracool dwarfs

Astrometric planet search around southern ultracool dwarfs

GaiaData Release 3

Astrometric planet search around southern ultracool dwarfs

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