A new optical extinction law and distance estimate for the Taurus-Auriga molecular cloud

Kenyon, Scott J.; Dobrzycka, D.; Hartmann, L.

doi:10.1086/117200

Cited by 304 publications

(317 citation statements)

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“…The Taurus star-formation region has a distance of 140 pc (Kenyon et al 1994;Wichmann et al 1998), which is nearby, and extends over a region of (100 • ) 2 on the sky. The age of its population is ≈1 Myr.…”

Section: Taurusmentioning

confidence: 99%

Inverse dynamical population synthesis

Marks

Kroupa

2012

A&A

253

302

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Binary populations in young star clusters show multiplicity fractions both lower and up to twice as high as those observed in the Galactic field. We follow the evolution of a population of binary stars in dense and loose star clusters starting with an invariant initial binary population and a formal multiplicity fraction of unity, and demonstrate that these models can explain the observed binary properties in Taurus, ρ Ophiuchus, Chamaeleon, Orion, IC 348, Upper Scorpius A, Praesepe, and the Pleiades. The model needs to consider solely different birth densities for these regions. The evolved theoretical orbital-parameter distributions are highly probable parent distributions for the observed ones. We constrain the birth conditions (stellar mass, M ecl , and half-mass radius, r h ) for the derived progenitors of the star clusters and the overall present-day binary fractions allowed by the present model. The results compare very well with properties of molecular cloud clumps on the verge of star formation. Combining these with previously and independently obtained constraints on the birth densities of globular clusters, we identify a weak stellar mass -half-mass radius correlation for cluster-forming cloud clumps, r h /pc ∝ (M ecl /M ) 0.13 ± 0.04 . The ability of the model to reproduce the binary properties in all the investigated young objects, covering present-day densities from 1−10 stars pc −3 (Taurus) to 2 × 10 4 stars pc −3 (Orion), suggests that environment-dependent dynamical evolution plays an important role in shaping the present-day properties of binary populations in star clusters, and that the initial binary properties may not vary dramatically between different environments.

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Section: Taurusmentioning

confidence: 99%

Inverse dynamical population synthesis

Marks

Kroupa

2012

A&A

253

302

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“…The Taurus star-formation region has a distance of ≈ 140 pc (Kenyon et al 1994;Wichmann et al 1998;Torres et al 2012) and extends over a region of one hundred square degrees on the sky. The age of its population is ≈ 1 − 2 Myr, but Daemgen et al (2015) found an additional co-moving sub-population of ≈ 20 Myr.…”

Section: The Stellar and Substellar Population Inmentioning

confidence: 99%

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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“…At a distance of 100 pc this corresponds to physical sizes of ∼400−500 AU and ∼700−1000 AU, respectively. The clouds observed in the c2d program are assumed to be located at distances A&A 519, A3 (2010) Enoch et al 2006), Taurus-Auriga (160 pc Kenyon et al 1994), Serpens (260 pc Straizys et al 1996). ranging from 125 pc (Ophiuchus) to 260 pc (Serpens) increasing the physical area observed.…”

Section: Separating Disk and Cloud Emission -Optimal Extractionmentioning

confidence: 99%

c2dSpitzerIRS spectra of embedded low-mass young stars: gas-phase emission lines

Lahuis

Dishoeck

Jørgensen

et al. 2010

A&A

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Context. A survey of mid-infrared gas-phase emission lines of H 2 , H 2 O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer "Cores to Disks" (c2d) legacy program. Aims. The environment of embedded protostars is complex both in its physical structure (envelopes, outflows, jets, protostellar disks) and the physical processes (accretion, irradiation by UV and/or X-rays, excitation through slow and fast shocks) which take place. The mid-IR spectral range hosts a suite of diagnostic lines which can distinguish them. A key point is to spatially resolve the emission in the Spitzer-IRS spectra to separate extended PDR and shock emission from compact source emission associated with the circumstellar disk and jets.Methods. An optimal extraction method is used to separate both spatially unresolved (compact, up to a few hundred AU) and spatially resolved (extended, thousand AU or more) emission from the IRS spectra. The results are compared with the c2d disk sample and literature PDR and shock models to address the physical nature of the sources. Conclusions. The observed emission on ≥1000 AU scales is characteristic of PDR emission and likely originates in the outflow cavities in the remnant envelope created by the stellar wind and jets from the embedded young stars. Weak shocks along the outflow wall can also contribute. The compact emission is likely of mixed origin, comprised of optically thick circumstellar disk and/or jet/outflow emission from the protostellar object.

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A new optical extinction law and distance estimate for the Taurus-Auriga molecular cloud

Cited by 304 publications

References 0 publications

Inverse dynamical population synthesis

Inverse dynamical population synthesis

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

c2dSpitzerIRS spectra of embedded low-mass young stars: gas-phase emission lines

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