The Tucana/Horologium, Columba, Ab Doradus, and Argus Associations: New Members and Dusty Debris Disks

Zuckerman, B.; Rhee, J.; Song, Inseok; Bessell, M. S.

doi:10.1088/0004-637x/732/2/61

Cited by 261 publications

(298 citation statements)

References 67 publications

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“…Additional evidence for a young age of the Columba association comes from the interferometric measurements of the proposed member HR 8799 (Zuckerman et al 2011), where the radius of the star is consistent with an age ∼30 Myr (Baines et al 2012) 9 . Dynamical stability studies of the planetary system that orbits HR 8799 provide additional indirect evidence for a young system age.…”

Section: Tucana Columba Carina and Argusmentioning

confidence: 93%

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

Desidera

Covino

Messina

et al. 2015

A&A

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Context. Young, close stars are ideal targets for searching planets using the direct imaging technique. The determination of stellar parameters is crucial for the interpretation of imaging survey results, particularly since the luminosity of substellar objects has a strong dependence on system age. Aims. We have conducted a large program with NaCo at the VLT to search for planets and brown dwarfs in wide orbits around 86 stars. A large fraction of the targets observed with NaCo were poorly investigated in the literature. We performed a study to characterize the fundamental properties (age, distance, and mass) of the stars in our sample. To improve target age determinations, we compiled and analyzed a complete set of age diagnostics. Methods. We measured spectroscopic parameters and age diagnostics using dedicated observations acquired with FEROS and CORALIE spectrographs at La Silla Observatory. We also made extensive use of archival spectroscopic data and the results that are available in the literature. Additionally, we exploited photometric time-series, which are available in ASAS and Super-WASP archives, to derive a rotational period for a large fraction of our program stars. Results. We provided updated characterization of all the targets observed in the VLT NaCo Large program, a survey designed to probe the occurrence of exoplanets and brown dwarfs in wide orbits. The median distance and age of our program stars are 64 pc and 100 Myr, respectively. Nearly all the stars have masses between 0.70 and 1.50 M , with a median value of 1.01 M . The typical metallicity is close to solar with a dispersion that is smaller than that of samples usually observed in radial velocity surveys. Several stars are confirmed or proposed here to be members of close young moving groups. Eight spectroscopic binaries are identified.

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Section: Tucana Columba Carina and Argusmentioning

confidence: 93%

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

Desidera

Covino

Messina

et al. 2015

A&A

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“…van Leeuwen (2007) reported a Hipparcos parallax of 20.31 mas, placing it at a distance of r ≈ 49 pc. McDonald et al (2012) reported an effective temperature of T eff ≈ 6032 K, while the estimate of Vican & Schneider (2014) was T eff ≈ 6100 K. Furthermore, Vican & Schneider (2014) reported a radius of R ≈ 1.05 R , while Zuckerman et al (2011) presented the value R ≈ 1.08 R . We adopted the value 1.1 R .…”

Section: V1358 Orimentioning

confidence: 93%

“…Montes et al 2001), while HD 29615 has been proposed as a member of the Tucana/Horologium association indicating an age of ∼30 Myr (see e.g. Zuckerman et al 2011). They are, however, slightly hotter than the young Sun.…”

Section: Observed Stars and Their Adopted Stellar Parametersmentioning

confidence: 99%

Zeeman-Doppler imaging of active young solar-type stars

Hackman

Lehtinen

Rosén

et al. 2016

A&A

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Context. By studying young magnetically active late-type stars, i.e. analogues to the young Sun, we can draw conclusions on the evolution of the solar dynamo. Aims. We determine the topology of the surface magnetic field and study the relation between the magnetic field and cool photospheric spots in three young late-type stars. Methods. High-resolution spectropolarimetry of the targets was obtained with the HARPSpol instrument mounted at the ESO 3.6 m telescope. The signal-to-noise ratios of the Stokes IV measurements were boosted by combining the signal from a large number of spectroscopic absorption lines through the least squares deconvolution technique. Surface brightness and magnetic field maps were calculated using the Zeeman-Doppler imaging technique.Results. All three targets show clear signs of magnetic fields and cool spots. Only one of the targets, V1358 Ori, shows evidence of the dominance of non-axisymmetric modes. In two of the targets, the poloidal field is significantly stronger than the toroidal one, indicative of an α 2 -type dynamo, in which convective turbulence effects dominate over the weak differential rotation. In two of the cases there is a slight anti-correlation between the cool spots and the strength of the radial magnetic field. However, even in these cases the correlation is much weaker than in the case of sunspots. Conclusions. The weak correlation between the measured radial magnetic field and cool spots may indicate a more complex magnetic field structure in the spots or spot groups involving mixed magnetic polarities. Comparison with a previously published magnetic field map shows that on one of the stars, HD 29615, the underlying magnetic field changed its polarity between 2009 and 2013.

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“…Therefore, for a given detection threshold, observing younger stars is sensitive to lower mass planets. Our sample selection is based on recent publications on associations (AB Dor, β Pic, Her/Lyr, Argus, Tuc/Hor, Columba, and Upper Cen/Lupus) from Zuckerman et al (2011), Torres et al (2008 and Rhee et al (2007). Indeed, stars belonging to these moving groups share common kinematic properties and ages.…”

Section: Target Selectionmentioning

confidence: 99%

“…HIP 114189 / HR 8799 -HR 8799 is a well-known λ Boo, γ Dor star, surrounded by a debris disk ) and belonging to the 30 Myr-old Columba association (Zuckerman et al 2011). It hosts four planetary-mass companions between 14 and 68 AU (Marois et al 2008(Marois et al , 2010, which makes this multiple-planet system the first imaged so far.…”

Section: Substellar Companionsmentioning

confidence: 99%

A survey of young, nearby, and dusty stars conducted to understand the formation of wide-orbit giant planets

Rameau

Chauvin

Lagrange

et al. 2013

A&A

107

148

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Context. Over the past decade, direct imaging has confirmed the existence of substellar companions on wide orbits from their parent stars. To understand the formation and evolution mechanisms of these companions, their individual as well as the full population properties must be characterized. Aims. We aim at detecting giant planet and/or brown dwarf companions around young, nearby, and dusty stars. Our goal is also to provide statistics on the population of giant planets at wide-orbits and discuss planet formation models. Methods. We report the results of a deep survey of 59 stars, members of young stellar associations. The observations were conducted with the ground-based adaptive optics system VLT/NaCo at L -band (3.8 μm). We used angular differential imaging to reach the best detection performances down to the planetary mass regime. A statistical analysis of about 60% of the young and southern A-F stars closer than 65 pc allowed us to derive the fraction of giant planets on wide orbits. We used gravitational instability models and planet population synthesis models following the core-accretion scenario to discuss the occurrence of these companions. Results. We resolve and characterize new visual binaries and do not detect any new substellar companion. The survey's median detection performance reaches contrasts of 10 mag at 0.5 and 11.5 mag at 1.0 . We find the occurrence of planets to be between 10.8 and 24.8% at 68% confidence level assuming a uniform distribution of planets in the interval [1, 13] M J and [1, 1000] AU. Considering the predictions of planetary formation models, we set important constraints on the occurrence of massive planets and brown dwarf companions that would have formed by gravitational instability. We show that this mechanism favors the formation of rather massive clumps (M clump > 30 M J ) at wide (a > 40 AU) orbits, which may evolve dynamically and/or fragment. For the population of close-in giant planets that would have formed by core accretion (without considering any planet -planet scattering), our survey marginally explores physical separations (≤20 AU) and cannot constrain this population. We will have to wait for the next generation of planet finders to start exploring that population, and even for the extremely large telescopes for a more complete overlap with other planet-hunting techniques.

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The Tucana/Horologium, Columba, Ab Doradus, and Argus Associations: New Members and Dusty Debris Disks

Cited by 261 publications

References 67 publications

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits

Zeeman-Doppler imaging of active young solar-type stars

A survey of young, nearby, and dusty stars conducted to understand the formation of wide-orbit giant planets

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