Centimeter Continuum Observations of the Northern Head of the Hh 80/81/80n Jet: Revising the Actual Dimensions of a Parsec-Scale Jet

Masqué, Josep M.; Girart, J. M.; Estalella, R.; Rodrı́guez, Luis F.; Beltrán, M. T.

doi:10.1088/2041-8205/758/1/l10

Cited by 28 publications

(47 citation statements)

References 22 publications

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“…The flux-scaled images were corrected for the GMRT primary beams to produce the final images. At 1300 MHz, a bright source is observed (αJ2000: 18 h 19 m 36.9 s , δJ2000: −20 • 36 ′ 30.7 ′′ ) that contaminates the flux density measurement of the radio knot S34 (Source 34, nomenclature from Masqué et al 2012). The flux density in presence of the contamination due to side lobes from the bright source is 73 µJy.…”

Section: Gmrt Observations and Data Reductionmentioning

confidence: 99%

“…Here, we estimate the magnetic field strength in the individual radio condensations extending from S34 to HH80. In order to estimate the magnetic field strength, we employ the classi- Marti, Rodriguez & Reipurth (1993) and Masqué et al (2012).…”

Section: Magnetic Field Estimates In the Radio Condensationsmentioning

confidence: 99%

“…In the above equation, the frequencies, νo, ν1 and ν2 are expressed in GHz. For estimation of the magnetic field, we assume K ∼ 40 for Fermi accelerated electrons typical of astrophysical environments (Beck & Krause 2005), η ∼ 0.5 to account for clumpiness within the condensations that is evident from the detailed structure of HH80 and HH81 objects (Heathcote, Reipurth & Raga 1998), and φ ∼ 34 • (Masqué et al 2012). We consider the GMRT flux densities at frequency of νo = 0.610 GHz (2016) while the cutoff frequencies are taken as ν1 = 0.01 GHz and ν2 = 100 GHz.…”

Section: Magnetic Field Estimates In the Radio Condensationsmentioning

confidence: 99%

“…The jet is highly energetic and the measured velocities of condensations lie in the range 600 − 1400 km s −1 (Marti, Rodriguez & Reipurth 1995;Heathcote, Reipurth & Raga 1998). The radio emission from the jet as well as the HH objects have been the targets of several studies (Rodríguez & Reipurth 1989;Marti, Rodriguez & Reipurth 1993;Masqué et al 2012). Marti, Rodriguez & Reipurth (1993) carried out a careful analysis of radio emission in this region using the VLA (20, 6, 3.6 and 2 cm) and find that the knots have spectral indices of −0.3 suggesting the non-thermal nature of emission.…”

Section: Introductionmentioning

confidence: 99%

“…The jet comprises more than a dozen knots of radio emission with spacing of 1400 AU and widths of less than 500 AU. More recently, Masqué et al (2012) detected a radio knot further north that is likely to be associated with the jet, thus increasing the size of the jet to 18.7 pc. 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.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Gmrt Observations and Data Reductionmentioning

confidence: 99%

Section: Magnetic Field Estimates In the Radio Condensationsmentioning

confidence: 99%

Section: Magnetic Field Estimates In the Radio Condensationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Radio jets from young stellar objects

Anglada

Rodrı́guez²,

Carrasco-González³

2018

Astron Astrophys Rev

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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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