Circumprotostellar environments. I - Molecular outflows from protostar candidates in Taurus

Moriarty‐Schieven, G. H.; Wannier, P. G.; Tamura, Motohide; Keene, J.

doi:10.1086/171992

Cited by 48 publications

(55 citation statements)

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“…Feedback from outflows is one of them, as illustrated by the points in the vicinity of IRAS 04169+2702, which lies in B213-NW, near D = 1600 . This Class I source powers a well-known bipolar outflow previously studied in CO by Moriarty-Schieven et al (1992), Bontemps et al (1996), and Narayanan et al (2012). As Fig.…”

Section: Non-thermal Velocity Componentmentioning

confidence: 62%

Chains of dense cores in the Taurus L1495/B213 complex

Tafalla

Hacar

2015

A&A

146

174

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Context. Cloud fragmentation into dense cores is a critical step in the process of star formation. A number of recent observations show that it is connected to the filamentary structure of the gas, but the processes responsible for core formation remain mysterious. Aims. We studied the kinematics and spatial distribution of the dense gas in the L1495/B213 filamentary region of the Taurus molecular cloud with the goal of understanding the mechanism of core formation. Methods. We mapped the densest regions of L1495/B213 in N 2 H + (1-0) and C 18 O(2-1) with the IRAM 30 m telescope, and complemented these data with archival dust-continuum observations from the Herschel Space Observatory. Results. The dense cores in L1495/B213 are significantly clustered in linear chain-like groups about 0.5 pc long. The internal motions in these chains are mostly subsonic and the velocity is continuous, indicating that turbulence dissipation in the cloud has occurred at the scale of the chains and not at the smaller scale of the individual cores. The chains also present an approximately constant abundance of N 2 H + and radial intensity profiles that can be modeled with a density law that follows a softened power law. A simple analysis of the spacing between the cores using an isothermal cylinder model indicates that the cores have likely formed by gravitational fragmentation of velocity-coherent filaments. Conclusions. Combining our analysis of the cores with our previous study of the large-scale C 18 O emission from the cloud, we propose a two-step scenario of core formation in L1495/B213. In this scenario, named "fray and fragment", L1495/B213 originated from the supersonic collision of two flows. The collision produced a network of intertwined subsonic filaments or fibers (fray step). Some of these fibers accumulated enough mass to become gravitationally unstable and fragment into chains of closely-spaced cores.

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Section: Non-thermal Velocity Componentmentioning

confidence: 62%

Chains of dense cores in the Taurus L1495/B213 complex

Tafalla

Hacar

2015

A&A

146

174

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“…IRAS 04295+2251 has appeared pointlike in previous near-IR imaging observations (e.g., Park & Kenyon 2002) and is tentatively associated with a molecular outflow ( Moriarty-Schieven et al 1992). Previous investigators analyzed SEDs and scattered light images (separately) in the context of infalling envelope models and foundṀ ¼ ( 1 5 Kenyon et al 1993a;Whitney et al 1997).…”

Section: Iras 04295+2251mentioning

confidence: 88%

“…For this object, the best fit to the complete data set is obtained for disk+extinction and disk+envelope models, although the SED and 10 m spectra are fitted best by the disk+envelope model. and driving a molecular outflow (Myers et al 1988;Terebey et al 1989;Moriarty-Schieven et al 1992). Previous modeling of this source in terms of an infalling envelope model foundṀ $ 5 ; 10 À6 M yr…”

Section: Iras 04016+2610mentioning

confidence: 96%

Constraining the Evolutionary Stage of Class I Protostars: Multiwavelength Observations and Modeling

Eisner

Hillenbrand

Carpenter

et al. 2005

ApJ

118

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We present new Keck images at 0.9 m and OVRO 1.3 mm continuum images of five Class I protostars in the Taurus star-forming region. We analyze these data in conjunction with broadband spectral energy distributions (SEDs) and 8-13 m spectra from the literature using a Monte Carlo radiative transfer code. By fitting models for the circumstellar dust distributions simultaneously to the scattered light images, millimeter continuum data, and the SEDs, we attempt to distinguish between flared disks, infalling envelopes with outflow cavities, and combinations of disks and envelopes. For each of these circumstellar density distributions, we generate grids of models for varying geometries, dust masses, and accretion rates and determine the best fits by minimizing the residuals between model and data. Comparison of the residuals for best-fit disk, envelope, and disk+envelope models demonstrates that, in general, models incorporating both massive envelopes and massive embedded disks fit the imaging+SED data best. The implied envelope infall rates for these disk+envelope models are generally consistent with infall rates derived by previous investigators, although they are approximately an order of magnitude larger than inner disk accretion rates inferred from recent spectroscopic measurements. In addition, the disk masses inferred from our models are close to or larger than the limit for gravitationally stable disks, indicating that Class I disks may undergo periodic episodes of enhanced accretion, perhaps as a result of gravitational instabilities. An important caveat to these results is that in some cases, no single model can fit all of the imaging and SED data well, suggesting that further refinements to models of the circumstellar dust distributions around Class I sources are necessary. We discuss several potential improvements to the models, as well as new constraints that will become available with upcoming millimeter and infrared facilities.

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“…In addition, large‐scale outflow activity has been identified (e.g. Heyer et al 1987; Moriarty‐Schieven et al 1992; Wang et al 2001). The source is established as a prototypical small‐scale site of star formation.…”

Section: Introductionmentioning

confidence: 99%

A multiwavelength view of the protostellar binary IRAS 04325+2402: a case for turbulent fragmentation

Scholz¹,

Wood²,

Wilner³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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IRAS 04325+2402 (hereinafter IRAS 04325) is a complex protostellar system hosting two young stellar objects (AB and C) at a separation of 1250 au. Here, we present a new deep Gemini imaging and spectroscopy for the system covering the wavelength regime from 1 to 12 μm as well as Submillimeter Array interferometry at 870 μm, in combination with Spitzer and literature data. Based on this rich data set, we provide a comprehensive picture of IRAS 04325 over scales from a few au to several parsec. Object AB is a low‐mass star with a disc/envelope system and an outflow cavity, which is prominently seen in infrared images. Object C, previously suspected to be a brown dwarf, is likely a very low mass star, with an effective temperature of ∼3400 K. It features an edge‐on disc and an elongated envelope, and shows strong indications for accretion and ejection activities. Both objects are likely to drive parsec‐scale molecular outflows. The two objects are embedded in an isolated, dense molecular cloud core. High extinction, lack of X‐ray emission, and relatively high bolometric luminosity argue for a very young age below 1 Myr. The disc/outflow systems of objects AB and C are misaligned by ∼60° against each other and by 80° and 40° against the orbital plane of the binary. The system might be a good case for primordial misalignment, as opposed to misalignment caused by dynamical interactions, because the outflow direction is constant and the realignment time‐scale is likely larger than the system age. This favours turbulent fragmentation, rather than rotational fragmentation, as the formation scenario. We show that the spectral energy distributions and images for the two objects can be reproduced with radiative transfer models for disc/envelope systems. Our analysis provides reassurance in the established paradigm for the structure and early evolution of young stellar objects, but stresses the importance of developing three‐dimensional models with sophisticated dust chemistry.

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Circumprotostellar environments. I - Molecular outflows from protostar candidates in Taurus

Cited by 48 publications

References 0 publications

Chains of dense cores in the Taurus L1495/B213 complex

Chains of dense cores in the Taurus L1495/B213 complex

Constraining the Evolutionary Stage of Class I Protostars: Multiwavelength Observations and Modeling

A multiwavelength view of the protostellar binary IRAS 04325+2402: a case for turbulent fragmentation

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