THE SEARCH FOR PLANETARY MASS COMPANIONS TO FIELD BROWN DWARFS WITH<i>HST</i>/NICMOS

Stumpf, M. B.; Brandner, W.; Joergens, V.; Henning, Th.; Bouy, H.; Köhler, Rainer H.; Kasper, Markus

doi:10.1088/0004-637x/724/1/1

Cited by 13 publications

(14 citation statements)

References 96 publications

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“…We herewith established a low occurrence rate of giant planets around M/L dwarfs in the 0.1-0.8 AU separation range and closed the gap between the previously found low occurrence at smaller <0.05 AU (Blake et al 2010) and larger >1-2 AU (Stumpf et al 2010) separations.…”

Section: Occurrence Of Giant Planetssupporting

confidence: 84%

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Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2014

A&A

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Context. Extrasolar-planet searches that target very low-mass stars and brown dwarfs are hampered by intrinsic or instrumental limitations. Time series of astrometric measurements with precisions better than one milli-arcsecond can yield new evidence on the planet occurrence around these objects. Aims. We present first results of an astrometric search for planets around 20 nearby dwarf stars with spectral types M8-L2. Methods. Over a time-span of two years, we obtained I-band images of the target fields with the FORS2 camera at the Very Large Telescope. Using background stars as references, we monitored the targets' astrometric trajectories, which allowed us to measure parallax and proper motions, set limits on the presence of planets, and to discover the orbital motions of two binary systems. Results. We determined trigonometric parallaxes with an average accuracy of 0.09 mas ( 0.2%), which resulted in a reference sample for the study of ultracool dwarfs at the M/L transition, whose members are located at distances of 9.5-40 pc. This sample contains two newly discovered tight binaries (DE0630−18 and DE0823−49) and one previously known wide binary (DE1520−44). Only one target shows I-band variability >5 mmag rms. We derived planet exclusion limits that set an upper limit of 9% on the occurrence of giant planets with masses 5 M J in intermediate-separation (0.01-0.8 AU) orbits around M8-L2 dwarfs. Conclusions. We demonstrate that astrometric observations with an accuracy of 120 µas over two years are feasible from the ground and can be used for a planet-search survey. The detection of two tight very low-mass binaries shows that our search strategy is efficient and may lead to the detection of planetary-mass companions through follow-up observations.

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Section: Occurrence Of Giant Planetssupporting

confidence: 84%

“…At wider separations 2 AU, direct-imaging searches equally excluded a large population of giant planets (Stumpf et al 2010). Two very low-mass stars were found to host Earthmass (Kubas et al 2012, using microlensing) and Mars-sized A&A 565, A20 (2014) (Muirhead et al 2012, using Kepler) planets.…”

Section: Introductionmentioning

confidence: 99%

Astrometric planet search around southern ultracool dwarfs

Lazorenko

Ségransan

Martín

et al. 2014

A&A

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“…We ran 100 simulations, adding a binary at each point on a grid in separation, position angle and contrast ratio, in both J and H bands, as a co-joint fit. We then added Gaussian noise randomly to each of these, with the distribution given by our measured Stumpf et al (2010). A PSF broadening was noticed but no other unambiguous signal was detected.…”

Section: Possible New Companions At Higher Contrastsmentioning

confidence: 99%

Dancing in the Dark: New Brown Dwarf Binaries From Kernel Phase Interferometry

Pope

Martinache

Tuthill

2013

ApJ

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This paper revisits a sample of ultracool dwarfs in the Solar neighborhood previously observed with the Hubble Space Telescope's NICMOS NIC1 instrument. We have applied a novel high angular resolution data analysis technique based on the extraction and fitting of kernel phases to archival data. This was found to deliver a dramatic improvement over earlier analysis methods, permitting a search for companions down to projected separations of ∼1 AU on NIC1 snapshot images. We reveal five new close binary candidates and present revised astrometry on previously-known binaries, all of which were recovered with the technique. The new candidate binaries have sufficiently close separation to determine dynamical masses in a short-term observing campaign. We also present four marginal detections of objects which may be very close binaries or high contrast companions. Including only confident detections within 19 parsecs, we report a binary fraction of at least ǫ b = 17.2 +5.7 −3.7 %. The results reported here provide new insights into the population of nearby ultracool binaries, while also offering an incisive case study of the benefits conferred by the kernel phase approach in the recovery of companions within a few resolution elements of the PSF core.

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“…However, various radial velocity and high spatial resolution imaging works in the literature (see also Sect. 5.5) have not revealed the presence of a second, massive object in relatively close orbits around J0045+1634, J0355+1133, J1726+1538, and J2208+2921 (Reid et al , 2006Bouy et al 2003;Bernat et al 2010;Blake et al 2010;Stumpf et al 2010). Our age estimate for J0355+1133 (120 As explained in Kirkpatrick (2005) and Cruz et al (2009), the β and γ appended to the L subtypes indicate intermediateand very low-gravity spectra, respectively.…”

Section: Hr Diagram: Ages and Massesmentioning

confidence: 66%

Trigonometric parallaxes of young field L dwarfs

Osorio

Béjar

Miles-Páez

et al. 2014

A&A

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Aims. We aim to determine the trigonometric parallaxes and proper motions of a sample of ten field L0-L5 dwarfs with spectroscopic evidence for low-gravity atmospheres. The ten sources were located in color-absolute magnitude diagrams and in the HertzsprungRussell (HR) diagram for age and mass derivations and were compared with field and star cluster dwarfs of related spectral classification and with state-of-the-art solar-metallicity evolutionary models. Methods. We obtained J and K s imaging data using 2-4 m class telescopes with a typical cadence of one image per month between 2010 January and 2012 December, in which the data cover a time baseline of nearly three years. We also obtained low resolution optical spectra (R ∼ 300, 500-1100 nm) using the 10 m Gran Telescopio de Canarias to assess the presence of lithium absorption in four targets and confirm their young age. The derived parallaxes and proper motions were combined with data from the literature to determine T eff , luminosity, and space velocities. All this information along with the lithium observations was used to assess the ages and masses of the sample. The astrometric curves were also examined for periodic perturbations indicative of unseen companions. Results. Trigonometric parallaxes and proper motions were derived to typical accuracies of a milliarcsecond (mas) and ±10 mas yr −1 , respectively. All ten L dwarfs have large motions (μ ≥ 70 mas yr −1 ) and are located at distances between 9 and 47 pc. They lie above and on the sequence of field dwarfs in the diagrams of absolute J and K s magnitude versus spectral type and luminosity versus effective temperature, which implies ages similar to or smaller than those typical of the field. In the HR diagram, 2MASS J00332386−1521309 (L4), 2MASS J00452143+1634446 (L2), 2MASS J03552337+1133437 (L5), 2MASS J05012406−0010452 (L4), G 196-3B (L3), 2MASS J17260007+1538190 (L3), and 2MASS J22081363+2921215 (L3) occupy locations that are compatible with the most likely ages in the interval ≈10-500 Myr if they are single objects. All of these dwarfs (except for 2MASS J00332386−1521309) show strong lithium absorption at 670.8 nm, thus confirming the young ages and masses ranging from ≈11 through ≈45 M Jup for this subsample. The detection of atomic lithium in the atmosphere of 2MASS J00452143+1634446 (L2) is reported for the first time. The lack of lithium in 2MASS J00332386−1521309 (L4) is not compatible with its position in the HR diagram, suggesting a spectral type earlier than L4. The remaining three dwarfs, 2MASS J02411151−0326587 (L0), 2MASS J10224821+5825453 (L1), and 2MASS J15525906+2948485 (L0) have locations in the HR diagram indicative of older ages and higher masses consistent with the observed lithium depletion previously published. The dynamical studies based on space velocities derived from our parallaxes and proper motions fully support the aforementioned results for 2MASS J00452143+1634446, 2MASS J03552337+1133437, G 196-3B, 2MASS J10224821+5825453, and 2MASS J15525906+2948485. We did ...

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THE SEARCH FOR PLANETARY MASS COMPANIONS TO FIELD BROWN DWARFS WITHHST/NICMOS

Cited by 13 publications

References 96 publications

Astrometric planet search around southern ultracool dwarfs

Astrometric planet search around southern ultracool dwarfs

Dancing in the Dark: New Brown Dwarf Binaries From Kernel Phase Interferometry

Trigonometric parallaxes of young field L dwarfs

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