Origin of the ionized wind in MWC 349A

Báez-Rubio, A.; Martı́n-Pintado, J.; Thum, C.; Planesas, P.; Redondo, Josefina Torres

doi:10.1051/0004-6361/201424389

Cited by 15 publications

(16 citation statements)

References 25 publications

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“…Our detection of HC 3 N * emission, indicative of extremely high column densities of gas and dust around the heating protostars, suggest that the condensations detected in the continuum by Leroy et al (2018) represent indeed the earliest phases of SSCs evolution. In fact, some of them (10, 11 and 13) show strong Hydrogen recombination lines likely associated to H ii regions with a steep electron density profile (Báez-Rubio et al 2018), as expected for extremely young UCHII regions (Jaffe & Martín-Pintado 1999;Báez-Rubio et al 2014). We have detected 8 out of 14 SSCs candidates in HC 3 N * (i.e.…”

Section: Sizessupporting

confidence: 64%

Super Hot Cores in NGC 253: witnessing the formation and early evolution of super star clusters

Rico-Villas

Martı́n-Pintado

González-Alfonso

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Using 0.2 (∼ 3 pc) ALMA images of vibrationally excited HC 3 N emission (HC 3 N * ) we reveal the presence of 8 unresolved Super Hot Cores (SHCs) in the inner 160 pc of NGC 253. Our LTE and non-LTE modelling of the HC 3 N * emission indicate that SHCs have dust temperatures of 200 − 375 K, relatively high H 2 densities of 1 − 6 × 10 6 cm −3 and high IR luminosities of 0.1−1×10 8 L . As expected from their short lived phase (∼ 10 4 yr), all SHCs are associated with young Super Star Clusters (SSCs). We use the ratio of luminosities form the SHCs (protostar phase) and from the free-free emission (ZAMS star phase), to establish the evolutionary stage of the SSCs. The youngest SSCs, with the larges ratios, have ages of a few 10 4 yr (proto-SSCs) and the more evolved SSCs are likely between 10 5 and 10 6 yr (ZAMS-SSCs). The different evolutionary stages of the SSCs are also supported by the radiative feedback from the UV radiation as traced by the HNCO/CS ratio, with this ratio being systematically higher in the young proto-SSCs than in the older ZAMS-SSCs. We also estimate the SFR and the SFE of the SSCs. The trend found in the estimated SFE (∼ 40% for proto-SSCs and > 85% for ZAMS-SSCs) and in the gas mass reservoir available for star formation, one order of magnitude higher for proto-SSCs, suggests that star formation is still going on in proto-SSCs. We also find that the most evolved SSCs are located, in projection, closer to the center of the galaxy than the younger proto-SSCs, indicating an inside-out SSC formation scenario.

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Section: Sizessupporting

confidence: 64%

Super Hot Cores in NGC 253: witnessing the formation and early evolution of super star clusters

Rico-Villas

Martı́n-Pintado

González-Alfonso

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…However, at the millimeter wavelengths, below 3 mm, this source presents strong, double-peaked hydrogen recombination lines (Martín-Pintado et al 1989). These spectra arise from a dense Keplerian-rotating disk, that is observed nearly edge-on (Weintroub et al 2008;Báez-Rubio et al 2014). The flux density of these features is an order or magnitude larger than expected from the LTE assumption and the inference that maser emission is at work seems well justified.…”

Section: Non-lte Radio Recombination Linesmentioning

confidence: 99%

Radio jets from young stellar objects

Anglada

Rodrı́guez²,

Carrasco-González³

2018

Astron Astrophys Rev

137

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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“…Other high-mass sources, MWC349A (Báez-Rubio et al 2014;Zhang et al 2017) and Orion Source I (Matthews et al 2010;Greenhill et al 2013;Issaoun et al 2017;Ginsburg et al 2018) also drive disc winds. There is still some debate as to whether MWC349A is a preor post-main sequence star, while in Orion Source I the radio emission is not consistent with an equatorial ionised disc wind (Matthews et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Chasing discs around O-type (proto)stars

Maud

Cesaroni

Kumar

et al. 2018

A&A

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We present high angular resolution (∼0.2 ) continuum and molecular emission line Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of G17.64+0.16 in Band 6 (220−230 GHz) taken as part of a campaign in search of circumstellar discs around (proto)-O-stars. At a resolution of ∼400 au the main continuum core is essentially unresolved and isolated from other strong and compact emission peaks. We detect SiO (5-4) emission that is marginally resolved and elongated in a direction perpendicular to the large-scale outflow seen in the 13 CO (2−1) line using the main ALMA array in conjunction with the Atacama Compact Array (ACA). Morphologically, the SiO appears to represent a disc-like structure. Using parametric models we show that the position-velocity profile of the SiO is consistent with the Keplerian rotation of a disc around an object between 10 and 30 M in mass, only if there is also radial expansion from a separate structure. The radial motion component can be interpreted as a disc wind from the disc surface. Models with a central stellar object mass between 20 and 30 M are the most consistent with the stellar luminosity (1 × 10 5 L ) and indicative of an O-type star. The H30α millimetre recombination line (231.9 GHz) is also detected, but spatially unresolved, and is indicative of a very compact, hot, ionised region co-spatial with the dust continuum core. The broad line-width of the H30α emission (full-width-half-maximum = 81.9 km s −1 ) is not dominated by pressure-broadening but is consistent with underlying bulk motions. These velocities match those required for shocks to release silicon from dust grains into the gas phase. CH 3 CN and CH 3 OH thermal emission also shows two arc shaped plumes that curve away from the disc plane. Their coincidence with OH maser emission suggests that they could trace the inner working surfaces of a wide-angle wind driven by G17.64 which impacts the diffuse remnant natal cloud before being redirected into the large-scale outflow direction. Accounting for all observables, we suggest that G17.64 is consistent with a O-type young stellar object in the final stages of protostellar assembly, driving a wind, but that has not yet developed into a compact HII region. The existance and detection of the disc in G17.64 is likely related to its isolated and possibly more evolved nature, traits which may underpin discs in similar sources.The reduced datacubes are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

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Origin of the ionized wind in MWC 349A

Cited by 15 publications

References 25 publications

Super Hot Cores in NGC 253: witnessing the formation and early evolution of super star clusters

Super Hot Cores in NGC 253: witnessing the formation and early evolution of super star clusters

Radio jets from young stellar objects

Chasing discs around O-type (proto)stars

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