scholarly journals A Multi-Epoch Study of Radio Continuum Emission from Massive Protostars

2020 ◽  
Author(s):  
W O Obonyo ◽  
S L Lumsden ◽  
M G Hoare ◽  
S E Kurtz ◽  
S J D Purser
Keyword(s):  
Spectral Index ◽  
The Other ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Gas Bubble ◽  
Large Array ◽  
Proper Motions ◽  
Very Large Array ◽  
The Core ◽  
Displacement Vectors

Abstract We report the results of the Jansky Very Large Array (JVLA) observation of five massive protostars at 6 and 22.2 GHz. The aim of the study was to compare their current fluxes and positions with previous observations to search for evidence of variability. Most of the observed sources present the morphologies of a thermal core, hosting the protostar and exhibiting no proper motion, and associated non-thermal radio lobes that are characterised by proper motions and located away from the thermal core. Some of the protostars drive jets whose lobes have dissimilar displacement vectors, implying precession of the jets or the presence of multiple jet drivers. The jets of the protostars were found to have proper motions that lie in the range 170≤v ≤650 kms−1, and precessions of periods 40≤p ≤50 years and angles 2≤α ≤ 10○, assuming that their velocities v =500 kms−1. The core of one of the sources, S255 NIRS 3, which was in outburst at the time of our observations, showed a significant change in flux compared to the other sources. Its spectral index decreased during the outburst, consistent with the model of an expanding gas bubble. Modelling the emission of the outburst as that of a new non-thermal lobe that is emerging from a thermal core whose emission enshrouds that of the lobe also has the potential to account for the increase in flux and a decrease in the spectral index of the source’s outburst.

Bipolar outflow of gas in the spiral galaxy NGC 3079

1986 ◽  
Vol 64 (4) ◽  
pp. 531-535 ◽  
Author(s):  
Nebojsa Duric ◽  
E. R. Seaquist
Keyword(s):  
Spectral Index ◽  
Spiral Galaxy ◽  
Central Region ◽  
Qualitative Description ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Bipolar Outflow ◽  
The Galaxy

Very large array, radio-continuum observations of the edge-on spiral galaxy NGC 3079 are presented. The observations reveal that the nucleus has windlike properties and that the central region of the galaxy exhibits an unusual figure-eight morphology that shows evidence of severe depolarization and a flattening spectral index away from the nucleus. A qualitative description of a model is presented to account for the observed radio properties. It is shown that a wind-driven shock propagating away from the nucleus and focused by the ambient disk gas can give rise to the observed morphology.

scholarly journals Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State

2021 ◽  
Vol 923 (1) ◽  
pp. 3
Author(s):  
Amruta D. Jaodand ◽  
Adam T. Deller ◽  
Nina Gusinskaia ◽  
Jason W. T. Hessels ◽  
James C. A. Miller-Jones ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Millisecond Pulsar ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limit ◽  
5 Ghz ◽  
Variable Radio

Abstract 3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L 5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L 2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.

scholarly journals Protostellar Outflows at the EarliesT Stages (POETS)

2018 ◽  
Vol 619 ◽  
pp. A107 ◽  
Author(s):  
A. Sanna ◽  
L. Moscadelli ◽  
C. Goddi ◽  
V. Krishnan ◽  
F. Massi
Keyword(s):  
Spectral Index ◽  
Young Stars ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Stellar Winds ◽  
Distance Measurements ◽  
Very Large Array ◽  
Star Forming ◽  
Continuum Source ◽  
Star Forming Regions

Context. Weak and compact radio continuum and H2O masers are preferred tracers of the outflow activity nearby very young stars. Aims. We want to image the centimeter free–free continuum emission in the range 1–7 cm (26–4 GHz), which arises in the inner few 1000 au from those young stars also associated with bright H2O masers. We seek to study the radio continuum properties in combination with the H2O maser kinematics to quantify the outflow energetics powered by single young stars. Methods. We made use of the Karl G. Jansky Very Large Array (VLA) in the B configuration at K band and the A configuration at both Ku and C bands in order to image the radio continuum emission toward 25 H2O maser sites with an angular resolution and thermal rms on the order of 0.′′1 and 10 μJy beam−1, respectively. These targets add to our pilot study of 11 maser sites previously presented. The sample of H2O maser sites was selected among those regions that have accurate distance measurements, obtained through maser trigonometric parallaxes, and H2O maser luminosities in excess of 10−6 L⊙. Results. We present high-resolution radio continuum images of 33 sources belonging to 25 star-forming regions. In each region, we detect radio continuum emission within a few 1000 au of the H2O masers’ position; 50% of the radio continuum sources are associated with bolometric luminosities exceeding 5 × 103 L⊙, including W33A and G240.32 + 0.07. We provide a detailed spectral index analysis for each radio continuum source, based on the integrated fluxes at each frequency, and produce spectral index maps with the multifrequency synthesis deconvolution algorithm of CASA. The radio continuum emission traces thermal bremsstrahlung in (proto)stellar winds and jets that have flux densities at 22 GHz below 3 mJy and spectral index values between − 0.1 and 1.3. We prove a strong correlation (r > 0.8) between the radio continuum luminosity (Lrad) and the H2O maser luminosity (LH2O) of (L8 GHz∕mJy kpc2) = 103.8 × (LH2O L⊙)0.74. This power-law relation is similar to that between the radio continuum and bolometric luminosities, which confirms earlier studies. Since H2O masers are excited through shocks driven by (proto)stellar winds and jets, these results provide support to the idea that the radio continuum emission around young stars is dominated by shock ionization, and this holds over several orders of magnitude of stellar luminosites (1–105 L⊙).

scholarly journals Observations of H2O maser and continuum emission in AFGL 2591

2002 ◽  
Vol 206 ◽  
pp. 68-71
Author(s):  
Miguel A. Trinidad ◽  
Salvador Curiel ◽  
Jorge Cantó ◽  
José M. Torrelles ◽  
Luis F. Rodríguez ◽  
...  
Keyword(s):  
Radio Continuum ◽  
Continuum Emission ◽  
Molecular Flow ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Bipolar Outflow ◽  
Maser Line ◽  
H Ii Region

We report results of radio continuum (1.3 and 3.6 cm) and H2O maser line observations, made with the Very Large Array (A configuration), toward the star-forming region AFGL 2591. We detected 85 maser spots toward this region, which are distributed in three main groups. Two of these groups spatially coincide with the radio continuum sources VLA 2 and VLA 3. The maser spots associated with VLA 3 are distributed along a shell-like structure of 0.01 and nearly perpendicular to the CO bipolar outflow. We propose that VLA 3 is the center of the observed molecular flow in this region. Finally, we confirm that AFGL 2591 region is a cluster of B type stars, each one with its own optically thin H II region.

A DEEP VERY LARGE ARRAY RADIO CONTINUUM SURVEY OF THE CORE AND OUTSKIRTS OF THE COMA CLUSTER

2009 ◽  
Vol 137 (5) ◽  
pp. 4436-4449 ◽  
Author(s):  
Neal A. Miller ◽  
Ann E. Hornschemeier ◽  
Bahram Mobasher
Keyword(s):  
Radio Continuum ◽  
Large Array ◽  
Coma Cluster ◽  
Very Large Array ◽  
The Core

scholarly journals Neutral Hydrogen in HCG 95

2000 ◽  
Vol 174 ◽  
pp. 154-157 ◽  
Author(s):  
W. K. Huchtmeier ◽  
Lourdes Verdes-Montenegro ◽  
Min Yun ◽  
A. del Olmo ◽  
J. Perea
Keyword(s):  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Foreground Object ◽  
Very Large Array ◽  
Group Center

AbstractWe have observed Hɪ emission and radio continuum emission from the compact group of galaxies HCG 95 with the Very Large Array (VLA)1. Two continuum sources coincide in with galaxies in this group: HCG 95 B (3.9 mJy) and HCG95C (6 mJy). Hɪ emission and absorption was detected in galaxy HCG 95 C. In addition we detected two so far unknown dwarf galaxies by their Hɪ emission within 3.5 arcmin of the group center. We did not detect galaxy b (with ç = 8000 kms−1 it is obviously a foreground object) and galaxy d — an edge-on Sc galaxy. This group definitely is Hɪ deficient compared with the average Hɪ content expected for spiral galaxies of the same luminosity and type. The first-ranked elliptical galaxy HCG 95 A might be responsible for the observed Hɪ deficiency in this group.

The Nature of Radio Continuum Emission at Very Low Metallicity: Very Large Array Observations of I Zw 18

2005 ◽  
Vol 621 (1) ◽  
pp. L21-L24 ◽  
Author(s):  
John M. Cannon ◽  
Fabian Walter ◽  
Evan D. Skillman ◽  
Liese van Zee
Keyword(s):  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Very Large Array ◽  
Low Metallicity

scholarly journals CHANG-ES. IV. RADIO CONTINUUM EMISSION OF 35 EDGE-ON GALAXIES OBSERVED WITH THE KARL G. JANSKY VERY LARGE ARRAY IN D CONFIGURATION—DATA RELEASE 1

2015 ◽  
Vol 150 (3) ◽  
pp. 81 ◽  
Author(s):  
Theresa Wiegert ◽  
Judith Irwin ◽  
Arpad Miskolczi ◽  
Philip Schmidt ◽  
Silvia Carolina Mora ◽  
...  
Keyword(s):  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Very Large Array ◽  
Data Release ◽  
Configuration Data

scholarly journals Water maser and radio continuum emission towards IRAS 23139+5939

2007 ◽  
Vol 3 (S242) ◽  
pp. 180-181
Author(s):  
M. A. Trinidad ◽  
S. Curiel ◽  
J. M. Torrelles ◽  
L. F. Rodríguez ◽  
V. Migenes ◽  
...  
Keyword(s):  
Flux Density ◽  
Line Emission ◽  
The Other ◽  
Radio Continuum ◽  
High Mass ◽  
Continuum Emission ◽  
Maser Line ◽  
Water Masers ◽  
Water Maser ◽  
The Continuum

AbstractWe present simultaneous observations of continuum (3.5 and 1.3cm) and water maser line emission (1.3cm) carried out with the VLA-A toward the high-mass object IRAS 23139+5939. We detected two radio continuum sources at 3.5cm separated by 0”5 (~2400 AU), I23139 and I23139S. Based on the observed continuum flux density and the spectral index, we suggest that I23139 is a thermal radio jet associated with a high-mass YSO. On the other hand, based on the spatio-kinematical distribution of the water masers, together with the continuum emission information, we speculate that I23139S is also a jet source powering some of the masers detected in the region.

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