Sub-Stellar Companions and Stellar Multiplicity in the Taurus Star-Forming Region

Daemgen, S.; Bonavita, M.; Jayawardhana, Ray; Lafrenière, David; Janson, Markus

doi:10.1088/0004-637x/799/2/155

Cited by 53 publications

(93 citation statements)

References 88 publications

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“…A weak correlation of binary fraction with increasing primary mass shows up as well for hydrogen-burning stars since lower mass binaries have on average a lower binding energy and are more susceptible to dissolution. This trend is as well qualitatively consistent to Daemgen et al (2015)'s results. The features occuring at the depicted mass limits for star-like formation and peripheral fragmentation are otherwise similar.…”

Section: Results: the Primary-mass Dependent Binarysupporting

confidence: 92%

“…Combining both populations results in a weak ≈ 1σ trend. Daemgen et al (2015) show their results for Taurus to compare well to earlier results obtained for Upper Sco (Lafrenière et al 2014). In Fig.…”

Section: Results: the Primary-mass Dependent Binarysupporting

confidence: 84%

“…find that the initially binary-dominated population changes on a crossingtime scale, i.e the resulting distributions after a few Myr depends only on the initial stellar density, the population should not be strongly altered beyond that time. Upon applying the operator for a moderate initial density (350 M ⊙ pc −3 , see Marks & Kroupa 2012) on the initial distributions for Taurus' age of ≈ 1 Myr, we see that the agreement with Daemgen et al (2015)'s data persists for the processed initial population.…”

Section: The Separation Distributionmentioning

confidence: 52%

“…In a high resolution imaging study Kraus et al (2011) find that 2/3−3/4 of all Taurus stars are multiple. In the most recent near-infrared imaging search for stellar and substellar companions Daemgen et al (2015) target 64 Taurus members with masses between 0.2 and 3M ⊙ , identifying secondaries down to 2M Jup . Within their 90% completeness limit they find a raw multiplicity fraction of 26.3 +6.6 −4.9 % in the separation range 10 − 1500 AU.…”

Section: The Stellar and Substellar Population Inmentioning

confidence: 99%

“…Note that these numbers are sensitive to the chosen limits for star-like formation and peripheral fragmentation. Daemgen et al 2015). Daemgen et al (2015)'s data is constructed using the physically bound pairs among 64 targets associated with Taurus (their table 2, see Sec.…”

Section: The Imfmentioning

confidence: 99%

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Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Marks¹,

Martín

Béjar

et al. 2017

A&A

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Context. Whether brown dwarfs (BDs) form just as stars directly from the gravitational collapse of a molecular cloud core ("star-like") or whether BDs and some very low-mass stars (VLMSs) constitute a separate population which form alongside stars comparable to the population of planets, e.g. through circumstellar disk ("peripheral") fragmentation, is one of the key questions of the star-formation problem. Aims. For young stars in Taurus-Auriga the binary fraction has been shown to be large with little dependence on primary mass above ≈ 0.2M⊙, while for BDs it is < 10%. Here we investigate a case in which BDs in Taurus formed dominantly, but not exclusively, through peripheral fragmentation, which naturally results in low binary fractions. The decline of the binary frequency in the transition region between star-like formation and peripheral formation is modelled. Methods. A dynamical population synthesis model is employed in which stellar binary formation is universal with a large binary fraction close to unity. Peripheral objects form separately in circumstellar disks with a distinctive initial mass function (IMF), own orbital parameter distributions for binaries and a low binary fraction according to observations and expectations from smoothed particle hydrodynamics (SPH) and grid-based computations. A small amount of dynamical processing of the stellar component is accounted for as appropriate for the low-density Taurus-Auriga embedded clusters. Results. The binary fraction declines strongly in the transition region between star-like and peripheral formation, exhibiting characteristic features. The location of these features and the steepness of this trend depend on the masslimits for star-like and peripheral formation. Such a trend might be unique to low density regions like Taurus which host dynamically largely unprocessed binary populations in which the binary fraction is large for stars down to M-dwarfs and low for BDs. Conclusions. The existence of a strong decline in the binary fraction -primary mass diagram will become verifiable in future surveys on BD and VLMS binarity in the Taurus-Auriga star forming region. It is a test of the (non-)continuity of star formation along the mass-scale, the separateness of the stellar and BD populations and the dominant formation channel for BDs and BD binaries in regions of low stellar density hosting dynamically unprocessed populations.

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Section: Results: the Primary-mass Dependent Binarysupporting

confidence: 92%

Section: Results: the Primary-mass Dependent Binarysupporting

confidence: 84%

Section: The Separation Distributionmentioning

confidence: 52%

Section: The Stellar and Substellar Population Inmentioning

confidence: 99%

Section: The Imfmentioning

confidence: 99%

See 3 more Smart Citations

Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Marks¹,

Martín

Béjar

et al. 2017

A&A

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Affordable échelle spectroscopy with a 60 cm telescope

et al. 2015

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A new fiber-fed spectrograph was installed at the 60 cm telescope of the Stará Lesná Observatory. The article presents tests of its performance (spectral resolution, signal-to-noise ratio, radial-velocity stability) and reports observations of selected variable stars and exoplanet host stars. First test observations show that the spectrograph is an ideal tool to observe bright eclipsing and spectroscopic binaries but also symbiotic and nova-like stars. The radial-velocity stability (60-80 m s −1 ) is sufficient to study spectroscopic binaries and to detect easily the orbital motion of hot-Jupiter extrasolar planets around bright stars.

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Search for associations containing young stars (SACY)

Elliott

Huélamo

Bouy

et al. 2015

A&A

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Context. Young loose nearby associations are unique samples of close (<150 pc), young (≈5-100 Myr) pre-main-sequence (PMS) stars. A significant number of members of these associations have been identified in the SACY (search for associations containing young stars) collaboration. We can use the proximity and youth of these members to investigate key ingredients in star formation processes, such as multiplicity. Aims. With the final goal of better understanding multiplicity properties at different evolutionary stages of PMS stars, we present the statistics of identified multiple systems from 113 confirmed SACY members. We derive multiplicity frequencies, mass-ratio, and physical separation distributions in a consistent parameter space, and compare our results to other PMS populations and the field. Methods. We have obtained adaptive-optics assisted near-infrared observations with the Nasmyth Adaptive Optics System and NearInfrared Imager and Spectrograph (NACO), ESO/VLT, and the Infrared Camera for Adaptive optics at Lick observatory (IRCAL), Lick Observatory, for at least one epoch of all 113 SACY members. We have identified multiple systems using co-moving propermotion analysis for targets with multi-epoch data, and using contamination estimates in terms of mass-ratio and physical separation for targets with single-epoch data. We have explored ranges in projected separation and mass-ratio of a [3-1000 au], and q [0.1-1], respectively. Results. We have identified 31 multiple systems (28 binaries and 3 triples). We derive a multiplicity frequency (MF) of MF 3−1000 au = 28.4 +4.7 −3.9 % and a triple frequency (TF) of TF 3-1000 au = 2.8 +2.5 −0.8 % in the separation range of 3-1000 au. We do not find any evidence for an increase in the MF with primary mass. The estimated mass-ratio of our statistical sample (with power-law index γ = −0.04 ± 0.14) is consistent with a flat distribution (γ = 0). Conclusions. Analysis from previous work using tight binaries indicated that the underlying multiple system distribution of the SACY dataset and the young star-forming region Taurus are statistically similar, supporting the idea that these two populations formed in a similar way. In this work, we show further similarities (but also hints of discrepancies) between the two populations: flat mass-ratio distributions and statistically similar MF and TF values. We also compared the SACY sample to the field (in the separation range of 19-100 au), finding that the two distributions are indistinguishable, suggesting a similar formation mechanism.

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Sub-Stellar Companions and Stellar Multiplicity in the Taurus Star-Forming Region

Cited by 53 publications

References 88 publications

Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Affordable échelle spectroscopy with a 60 cm telescope

Search for associations containing young stars (SACY)

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