A Magnetized Jet from a Massive Protostar

Carrasco-González, Carlos; Rodrı́guez, Luis F.; Anglada, Guillem; Martı́, Josep; Torrelles, J. M.; Osorio, M. R. Zapatero

doi:10.1126/science.1195589

Cited by 196 publications

(228 citation statements)

References 35 publications

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“…Jets and outflows are observed during the formation of stars over the whole stellar spectrum, from brown dwarfs (e.g., Whelan et al 2005Whelan et al , 2012 to high-mass stars (e.g., Motogi et al 2013;Carrasco-González et al 2010;Qiu et al 2011Qiu et al , 2008Qiu et al , 2007Zhang et al 2007), strongly indicating a universal launching mechanism at work (see § 4 and also chapter by Frank et al in this volume).…”

Section: Early Outflowsmentioning

confidence: 99%

The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and Outflows

Li¹,

Banerjee²,

Jørgensen³

et al. 2014

Protostars and Planets VI

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The formation of stars and planets are connected through disks. Our theoretical understanding of disk formation has undergone drastic changes in recent years, and we are on the brink of a revolution in disk observation enabled by ALMA. Large rotationally supported circumstellar disks, although common around more evolved young stellar objects, are rarely detected during the earliest, "Class 0" phase; a few excellent candidates have been discovered recently around both low-and high-mass protostars though. In this early phase, prominent outflows are ubiquitously observed; they are expected to be associated with at least small magnetized disks. Whether the paucity of large Keplerian disks is due to observational challenges or intrinsically different properties of the youngest disks is unclear. In this review we focus on the observations and theory of the formation of early disks and outflows, and their connections with the first phases of planet formation. Disk formation -once thought to be a simple consequence of the conservation of angular momentum during hydrodynamic core collapse -is far more subtle in magnetized gas. In this case, the rotation can be strongly magnetically braked. Indeed, both analytic arguments and numerical simulations have shown that disk formation is suppressed in the strict ideal magnetohydrodynamic (MHD) limit for the observed level of core magnetization. We review what is known about this "magnetic braking catastrophe", possible ways to resolve it, and the current status of early disk observations. Possible resolutions include non-ideal MHD effects (ambipolar diffusion, Ohmic dissipation and Hall effect), magnetic interchange instability in the inner part of protostellar accretion flow, turbulence, misalignment between the magnetic field and rotation axis, and depletion of the slowly rotating envelope by outflow stripping or accretion. Outflows are also intimately linked to disk formation; they are a natural product of magnetic fields and rotation and are important signposts of star formation. We review new developments on early outflow generation since PPV. The properties of early disks and outflows are a key component of planet formation in its early stages and we review these major connections.

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Section: Early Outflowsmentioning

confidence: 99%

The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and Outflows

Li¹,

Banerjee²,

Jørgensen³

et al. 2014

Protostars and Planets VI

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“…All the earlier observations of massive protostellar radio jets have been at higher frequencies (> 1.4 GHz) with signatures of non-thermal emission discerned in few cases (Curiel et al 1993;Marti, Rodriguez & Reipurth 1993;Garay et al 1996;Wilner, Reid & Menten 1999;Rodríguez-Kamenetzky et al 2016;Purser et al 2016). While synchrotron emission from a protostellar jet has been detected conclusively solely in one case with the measurement of polarised emission (Carrasco-González et al 2010), the presence of non-thermal emission in other jet systems is usually deduced through the radio spectral indices. If there is a combination of non-thermal and optically thick thermal emission in a region (with the latter anticipated for low radio frequencies), the radio spectral indices are expected to flatten out depending on the contribution of each process, since the slopes have opposite signs for the two processes (Rodríguez-Kamenetzky et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, polarised radio emission from the radio knots on the jet at ∼ 0.5 pc from the driving source has been discovered, a first for a jet associated with a protostar. This is interpreted as arising due to synchrotron emission from a magnetic field estimated to be ∼ 0.2 mG, that is parallel to the jet axis (Carrasco-González et al 2010). Shocked gas close to the central protostar and the associated HH objects HH80-81 have also been detected in soft X-rays (Pravdo, Tsuboi & Maeda 2004).…”

Section: Introductionmentioning

confidence: 99%

Detection of non-thermal emission from the massive protostellar jet HH80-81 at low radio frequencies using GMRT

Vig

Veena

Mandal

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Low radio frequencies are favourable for the identification of emission from non-thermal processes such as synchrotron emission. The massive protostellar jet associated with IRAS 18162-2048 (also known as the HH80-81 system) has been imaged at low radio frequencies: 325, 610 and 1300 MHz, using the Giant Metrewave Radio Telescope, India. This is the first instance of detection of non-thermal emission from a massive protostellar jet at such low radio frequencies. The central region displays an elongated structure characteristic of the jet. In addition, the associated Herbig-Haro objects such as HH80, HH81, HH80N, and other condensations along the inner regions of the jet exhibit negative spectral indices. The spectral indices of most condensations are ∼ −0.7, higher than the value of −0.3 determined earlier using high frequency measurements. The magnetic field values derived using radio flux densities in the present work, under the assumption of equipartition near minimum energy condition, lie in the range 116 − 180 µG. We probe into the hard X-ray nature of a source that has been attributed to HH80, in an attempt to reconcile the non-thermal characteristics of radio and X-ray measurements. The flux densities of condensations at 610 MHz, measured nearly 11 yrs apart, display variability that could be ascribed to the cooling of condensations, and emphasize the importance of coeval or nearly-coeval measurements for estimation of spectral indices.

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“…This scenario has been confirmed only very recently, after we presented the detection of linearly polarized emission from a YSO jet [22] (see Fig. 2).…”

Section: Synchrotron Emission In Yso Jetsmentioning

confidence: 87%

“…Although the Figure 2. Detection of linearly polarized emission at radio wavelengths in the YSO jet HH 80-81 (from [22]). In panel (b) the intensity of the polarized emission is shown in colors while the total continuum emission is shown in contours.…”

Section: Synchrotron Emission In Yso Jetsmentioning

confidence: 99%

Discovery of synchrotron emission from a YSO jet

Carrasco-González

Rodrı́guez

Anglada

et al. 2013

EPJ Web of Conferences

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Abstract. Synchrotron emission at radio wavelengths is commonly found in relativistic jets from active galactic nuclei (AGNs) and microquasars and allows the study of the magnetic field in these kind of jets. In contrast, the radio emission from jets from young stellar objecs (YSOs) is usually of very different nature: thermal free-free emission, which does not provide direct information about their magnetic field. Thus, that the magnetic field is still one of the most unknown physical parameters in these YSO jets. However, very recently, we detected for the first time polarized synchrotron emission from of a YSO (HH 80-81), a result that has two important consequences. First, it allows to study the magnetic field in a YSO jet by analyzing the properties of the synchrotron emission, in a similar way than in the case of AGN jets. Secondly, the presence of synchrotron emission in a YSO jet implies the presence of relativistic particles, and therefore, an acceleration mechanism that should be taken place in these "slow" jets. These results open new windows for the study of YSO jets in a wide range of wavelengths, from radio to X-and Gamma-rays.

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A Magnetized Jet from a Massive Protostar

Cited by 196 publications

References 35 publications

The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and Outflows

The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and Outflows

Detection of non-thermal emission from the massive protostellar jet HH80-81 at low radio frequencies using GMRT

Discovery of synchrotron emission from a YSO jet

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