Young Stars Near the Sun

Zuckerman, B.; Song, Inseok

doi:10.1146/annurev.astro.42.053102.134111

Cited by 576 publications

(641 citation statements)

References 147 publications

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“…Over the last two decades, a growing number of young stars much closer to the Sun and with wider ranging ages (∼8-150 Myr) have been identified (e.g., Zuckerman & Song 2004;Torres et al 2008). The proximity of these stars offers many benefits, including the possibility of spatially resolving binaries with smaller semimajor axes and correspondingly shorter orbital periods for dynamical mass determinations.…”

Section: Introductionmentioning

confidence: 99%

High-Precision Radio and Infrared Astrometry of LSPM J1314+1320ab. Ii. Testing Pre-Main-Sequence Models at the Lithium Depletion Boundary With Dynamical Masses

Dupuy

Forbrich

Rizzuto

et al. 2016

ApJ

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We present novel tests of pre-main-sequence models based on individual dynamical masses for the M7 binary LSPMJ1314+1320AB. Joint analysis of Keck adaptive optics astrometric monitoring along with Very Long Baseline Array radio data from a companion paper yield component masses of 92.8±0.6 M Jup (0.0885±0.0006 M ☉ ) and 91.7±1.0 M Jup (0.0875±0.0010 M ☉ ) and a parallactic distance of 17.249±0.013 pc. We find component luminosities consistent with the system being coeval at 80.8±2.5 Myr, according to BHAC15 evolutionary models. The presence of lithium is consistent with model predictions, marking the first test of the theoretical lithium depletion boundary using ultracool dwarfs of known mass. However, we find that the evolutionary model-derived average effective temperature (2950±5 K) is 180 K hotter than that given by a spectral type-T eff relation based on BT-Settl models (2770±100 K). We suggest that the dominant source of this discrepancy is model radii being too small by ≈13%. In a test mimicking the typical application of models by observers, we derive masses on the H-R diagram using luminosity and BT-Settl temperature. The estimated masses are lower by -(2.0σ) than we measure dynamically and would imply that this is a system of ≈50 M Jup brown dwarfs, highlighting the large systematic errors possible in H-R diagram properties. This is the first time masses have been measured for ultracool ( M6) dwarfs displaying spectral signatures of low gravity. Based on features in the infrared, LSPMJ1314+1320AB appears to have higher gravity than typical Pleiades and ABDor members, opposite the expectation given its younger age. The components of LSPMJ1314+1320AB are now the nearest, lowest mass pre-main-sequence stars with direct mass measurements.

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Section: Introductionmentioning

confidence: 99%

High-Precision Radio and Infrared Astrometry of LSPM J1314+1320ab. Ii. Testing Pre-Main-Sequence Models at the Lithium Depletion Boundary With Dynamical Masses

Dupuy

Forbrich

Rizzuto

et al. 2016

ApJ

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“…Using an average distance of 45 pc (from the EB and WD independent studies presented here), the RV derived by Torres et al (2006), and the proper motions measured by Hipparcos (see Table 1), we have derived the UVW components of the Galactic space velocity vector: UVW = −6.0, −0.5, −21.6 km s −1 . We have compared these values with the UVW vectors of young moving groups in the solar neighborhood included in Zuckerman & Song (2004) and Torres et al (2008a). We conclude that HIP 96515 A does not share the kinematical properties of any of these associations.…”

Section: Discussionmentioning

confidence: 99%

The triple system HIP 96515: a low-mass eclipsing binary with a DB white dwarf companion

Huélamo¹,

Vaz

Torres

et al. 2009

A&A

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Context. HIP 96515 A is a double-lined spectroscopic binary included in the SACY catalog as a potential young star. It has a visual companion (CCDM 19371-5134 B, HIP 96515 B) at 8. 6. If bound to the primary, the optical and infrared colors of this wide companion are consistent with those of a white dwarf. Aims. We attempt to characterize the system HIP 96515 A&B by studying each of its components. Methods. We analyzed spectroscopic and photometric observations of HIP 96515 A and its visual companion, HIP 96515 B. To confirm the system as a common proper-motion pair, we analyzed the astrometry of the components using high-angular resolution infrared observations obtained within a time span of two years, and archival astrometry. Results. The high-resolution optical spectrum of HIP 96515 A was used to derive a mass ratio, M 2 /M 1 , close to 0.9. The optical lightcurve of HIP 96515 A shows periodic variations with P orbital = 2.3456 days, revealing that HIP 96515 A is an eclipsing binary with preliminary orbital parameters of i = 89.• 0 ± 0.• 2, and M 1 = 0.59 ± 0.03 M and M 2 = 0.54 ± 0.03 M , for the primary and secondary, respectively, at an estimated distance of 42 ± 3 pc. This is a new eclipsing binary with component masses below 0.6 M . Multi-epoch observations of HIP 96515 A&B show that the system is a common proper-motion pair. The optical spectrum of HIP 96515 B is consistent with a pure helium atmosphere (DB) white dwarf. The comparison with evolutionary cooling sequence models provides T eff,WD = 19 126 ± 195 K, log g WD = 8.08, M WD /M = 0.6, and a distance of ∼46 pc. The estimated WD cooling age is ∼100 Myr and the total age of the object (including the main-sequence phase) is ∼400 Myr. Finally, if HIP 96515 A&B are coeval, and assuming a common age of ∼400 Myr, the comparison of the masses of the eclipsing binary members with evolutionary tracks shows that they are underestimated by ∼15% and 10%, for the primary and secondary, respectively.

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“…For stars with higher mass the most robust method is to identify stars in young moving groups which share a common age and determine a consistent age for all the stars in the group (e.g. Zuckerman & Song 2004). Alternatively, if an A star is in a binary system with a solar-type star, age-dating the solar-type secondary can yield the age of the higher-mass primary.…”

Section: Previous Methodsmentioning

confidence: 99%

“…We assign the star an age of 10 Myr as Zuckerman & Song (2004) identify HR 4796 as a member of the TW Hydra Association (TWA). We designed our NICI observations to place the known M2 companion HR 4796 B (Jura et al 1995) off the detector so that its light would not limit the dynamic range we could reach.…”

Section: Hr 4796mentioning

confidence: 99%

The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars

Nielsen

Liu

Wahhaj³

et al. 2013

Proc. IAU

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We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI PlanetFinding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (≈1.5-2.5 M ⊙ ) conducted to date and includes the planet hosts β Pic and Fomalhaut. We obtained follow-up astrometry of all candidate companions within 400 AU projected separation for stars in uncrowded fields and identified new low-mass −20 M Jup and 55 +20 −19 M Jup , making this system one of the rare substellar binaries in orbit around a star. Considering the contrast limits of our NICI data and the fact that we did not detect any planets, we use high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M ⊙ stars can have giant planets greater than 4 M Jup between 59 and 460 AU at 95% confidence, and fewer than 10% of these stars can have a planet more massive than 10 M Jup between 38 and 650 AU. Overall, we find that large-separation giant planets are not common around B and A stars: fewer than 10% of B and A stars can have an analog to the HR 8799 b (7 M Jup , 68 AU) planet at 95% confidence. We also describe a new Bayesian technique for determining the ages of field B and A stars from photometry and theoretical isochrones. Our method produces more plausible ages for high-mass stars than previous age-dating techniques, which tend to underestimate stellar ages and their uncertainties.

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Young Stars Near the Sun

Cited by 576 publications

References 147 publications

High-Precision Radio and Infrared Astrometry of LSPM J1314+1320ab. Ii. Testing Pre-Main-Sequence Models at the Lithium Depletion Boundary With Dynamical Masses

High-Precision Radio and Infrared Astrometry of LSPM J1314+1320ab. Ii. Testing Pre-Main-Sequence Models at the Lithium Depletion Boundary With Dynamical Masses

The triple system HIP 96515: a low-mass eclipsing binary with a DB white dwarf companion

The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars

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