AMI radio continuum observations of young stellar objects with known outflows★

Ainsworth, Rachael; Scaife, Anna M. M.; Ray, T. P.; Buckle, Jane; Davies, Matthew; Franzen, T. M. O.; Grainge, Keith; Hobson, M.; Hurley‐Walker, N.; Lasenby, A.; Olamaie, Malak; Perrott, Y. C.; Pooley, G. G.; Richer, J. S.; Rodríguez‐Gonzálvez, Carmen; Saunders, Richard D. E.; Schammel, Michel P.; Scott, Paul F.; Shimwell, T. W.; Titterington, D.; Waldram, Elizabeth

doi:10.1111/j.1365-2966.2012.20935.x

Cited by 21 publications

(11 citation statements)

References 142 publications

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“…The dot-dashed line corresponds to the radio luminosity predicted by the models of Curiel et al (1987Curiel et al ( , 1989 dent variable, as it was considered to be less affected by observational uncertainties. The correlation was confirmed with fits to larger samples (Anglada 1995Anglada et al 1998;Shirley et al 2007;AMI Consortium et al 2011a. The best fit to the low-luminosity sources (1 L bol 1000 L ) presented in Table 2 gives (see also …”

Section: Observational Properties: Radio Luminosity To Outflow Momentsupporting

confidence: 54%

Radio jets from young stellar objects

Anglada

Rodrı́guez²,

Carrasco-González³

2018

Astron Astrophys Rev

132

151

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Jets and outflows are ubiquitous in the process of formation of stars since outflow is intimately associated with accretion. Free-free (thermal) radio continuum emission in the centimeter domain is associated with these jets. The emission is relatively weak and compact, and sensitive radio interferometers of high angular resolution are required to detect and study it. One of the key problems in the study of outflows is to determine how they are accelerated and collimated. Observations in the cm range are most useful to trace the base of the ionized jets, close to the young central object and the inner parts of its accretion disk, where optical or near-IR imaging is made difficult by the high extinction present. Radio recombination lines in jets (in combination with proper motions) should provide their 3D kinematics at very small scale (near their origin). Future instruments such as the Square Kilometre Array (SKA) and the Next Generation Very Large Array (ngVLA) will be crucial to perform this kind of sensitive observations. Thermal jets are associated with both high and low mass protostars and possibly even with objects in the substellar domain. The ionizing mechanism of these radio jets appears to be related to shocks in the associated outflows, as suggested by the observed correlation between the centimeter luminosity and the outflow momentum rate. From this correlation and that of the centimeter luminosity with the bolometric luminosity of the system it will be possible to discriminate between unresolved HII regions and jets, and to infer additional physical properties of the embedded objects. Some jets associated with young stellar objects (YSOs) show indications of nonthermal emission (negative spectral indices) in part of their lobes. Linearly polarized synchrotron emission has been found in the jet of HH 80-81, allowing one to measure the direction and intensity of the jet magnetic field, a key ingredient to determine the collimation and ejection mechanisms. As only a fraction of the emission is polarized, very sensitive observations such as those that will be feasible with the interferometers previously mentioned are required to perform studies in a large sample of sources. Jets are present in many kinds of astrophysical scenarios. Characterizing radio jets in YSOs, where thermal emission allows one to determine their physical conditions in a reliable way, would also be useful in understanding acceleration and collimation mechanisms in all kinds of astrophysical jets, such as those associated with stellar and supermassive black holes and planetary nebulae.

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Section: Observational Properties: Radio Luminosity To Outflow Momentsupporting

confidence: 54%

Radio jets from young stellar objects

Anglada

Rodrı́guez²,

Carrasco-González³

2018

Astron Astrophys Rev

132

151

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“…An extensive literature search was conducted for integrated flux densities (on scales comparable with the GMRT) to include in the spectral energy distributions following Ainsworth et al (2012). Where uncertainties were not provided, an error of 10 per cent was used in the model fittings and this is indicated by a † .…”

Section: Appendix A: Sed Reference Tablesmentioning

confidence: 99%

GMRT detections of low-mass young stars at 323 and 608 MHz

Ainsworth¹,

Scaife²,

Green³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present the results of a pathfinder project conducted with the Giant Metrewave Radio Telescope (GMRT) to investigate protostellar systems at low radio frequencies. The goal of these investigations is to locate the break in the free-free spectrum where the optical depth equals unity in order to constrain physical parameters of these systems, such as the mass of the ionised gas surrounding these young stars. We detect all three target sources, L1551 IRS 5 (Class I), T Tau and DG Tau (Class II), at frequencies 323 and 608 MHz (wavelengths 90 and 50 cm, respectively). These are the first detections of low mass young stellar objects (YSOs) at such low frequencies. We combine these new GMRT data with archival information to construct the spectral energy distributions for each system and find a continuation of the optically thin free-free spectra extrapolated from higher radio frequencies to 323 MHz for each target. We use these results to place limits on the masses of the ionised gas and average electron densities associated with these young systems on scales of ∼ 1000 au. Future observations with higher angular resolution at lower frequencies are required to constrain these physical parameters further.

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“…Bontemps et al 1996;van der Marel et al 2013;Maud et al 2015;van Kempen et al 2016) and radio continuum jets (e.g. AMI Consortium et al 2012;Moscadelli et al 2016;Purser et al 2016). We include these sources for comparison in Figure 30.…”

Section: Comparison To Other Types Of Outflows / Quantifying the Outfmentioning

confidence: 99%

“…We note the typical uncertainty for these two methods of estimating the outflow force alongside the appropriate symbol in the plot legend. For comparison, we plot the outflow force estimates derived from radio continuum observations (triangles) byAMI Consortium et al (2012);Moscadelli et al (2016);Purser et al (2016) and the outflow force estimated from low-J CO lines (squares) byBontemps et al (1996); van der Marel et al (2013); Duarte-Cabral et al (2013); Maud et al (2015); van Kempen et al (2016).…”

mentioning

confidence: 99%

Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula

Reiter

Kiminki

Smith

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present proper motion measurements of 37 jets and HH objects in the Carina Nebula measured in two epochs of H α images obtained ∼10 yr apart with Hubble Space Telescope/Advanced Camera for Surveys (ACS). Transverse velocities in all but one jet are faster than 25 km s −1 , confirming that the jet-like H α features identified in the first epoch images trace outflowing gas. Proper motions constrain the location of the jet-driving source and provide kinematic confirmation of the intermediate-mass protostars that we identify for 20/37 jets. Jet velocities do not correlate with the estimated protostar mass and embedded driving sources do not have slower jets. Instead, transverse velocities (median ∼75 km s −1 ) are similar to those in jets from low-mass stars. Assuming a constant velocity since launch, we compute jet dynamical ages (median ∼10 4 yr). If continuous emission from inner jets traces the duration of the most recent accretion bursts, then these episodes are sustained longer (median ∼700 yr) than the typical decay time of an FU Orionis outburst. These jets can carry appreciable momentum that may be injected into the surrounding environment. The resulting outflow force, dP/dt, lies between that measured in low-and high-mass sources, despite the very different observational tracers used. Smooth scaling of the outflow force argues for a common physical process underlying outflows from protostars of all masses. This latest kinematic result adds to a growing body of evidence that intermediate-mass star formation proceeds like a scaled-up version of the formation of low-mass stars.

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AMI radio continuum observations of young stellar objects with known outflows★

Cited by 21 publications

References 142 publications

Radio jets from young stellar objects

Radio jets from young stellar objects

GMRT detections of low-mass young stars at 323 and 608 MHz

Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula

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