scholarly journals A VLA Radio Continuum Survey of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 60-60
Author(s):  
A. Zijlstra ◽  
S. R. Pottasch ◽  
C. Bignell
Keyword(s):  
High Resolution ◽  
Planetary Nebulae ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array

With the Very Large Array it is now possible to make high resolution radio continuum maps with sensitivity less than a milliJansky in an observation of only 5 minutes. We have used this so-called snapshot capability to measure about 400 PN north of declination −35. Most of the measurements were carried out at 6 cm. Some of the stronger sources were observed at several frequencies. Most sources were detected, however many nebulae were too weak to map in detail. The resolution ranges from 1.5″ to 1′, depending on the size of the PN. The selected PN have sizes in the range from 4″ to 6′.

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals 20cm VLA radio-continuum study of M31: Images and point source catalogues

2012 ◽  
pp. 41-68 ◽  
Author(s):  
T.J. Galvin ◽  
M.D. Filipovic ◽  
E.J. Crawford ◽  
N.F.H. Tothill ◽  
G.F. Wong ◽  
...  
Keyword(s):  
High Resolution ◽  
Angular Resolution ◽  
High Sensitivity ◽  
Radio Continuum ◽  
High Angular Resolution ◽  
Radio Sources ◽  
Large Array ◽  
Complete Sample ◽  
Very Large Array ◽  
Discrete Radio Sources

We present a series of new high-sensitivity and high-resolution radio-continuum images of M31 at ?=20 cm (?=1.4 GHz). These new images were produced by merging archived 20 cm radio-continuum observations from the Very Large Array (VLA) telescope. Images presented here are sensitive to rms=60 ?Jy and feature high angular resolution (<10??). A complete sample of discrete radio sources have been catalogued and analyzed across 17 individual VLA projects. We identified a total of 864 unique discrete radio sources across the field of M31. One of the most prominent regions in M31 is the ring feature for which we estimated total integrated flux of 706 mJy at ?=20 cm. We compare here detected sources to those listed in Gelfand et al. (2004) at ?=92 cm and find 118 sources in common to both surveys. The majority (61%) of these sources exhibit a spectral index of ? <-0.6 indicating that their emission is predominantly non-thermal in nature, that is more typical for background objects.

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 The VLA and VLBA at Millimeter Wavelengths

1994 ◽  
Vol 140 ◽  
pp. 41-43
Author(s):  
Edward B. Fomalont
Keyword(s):  
High Resolution ◽  
Radio Astronomy ◽  
Large Array ◽  
Very Large Array ◽  
Millimeter Wavelengths

AbstractAlthough the Very Large Array (VLA) and the Very Large Baseline Array (VLBA) were originally intended as centimeter wavelength instruments, the exciting results from high resolution millimeter radio astronomy over the last ten years have generated interest in pushing these arrays into the millimeter region. This report will describe two aspects of recent development at NRAO: the new capability of the VLA at 7mm wavelength which will be operational in 1994, and the completion of the VLBA with its anticipated use at 7mm and 3.6mm.

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.

scholarly journals A multifrequency study of the active star forming region NGC 6357

2006 ◽  
Vol 2 (S237) ◽  
pp. 400-400
Author(s):  
C. E. Cappa ◽  
R. H. Barbá ◽  
M. Arnal ◽  
N. Duronea ◽  
E. Fernández Lajús ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Massive Stars ◽  
Radio Continuum ◽  
Large Array ◽  
Schmidt Telescope ◽  
Ionized Gas ◽  
Very Large Array ◽  
Active Star ◽  
Star Forming ◽  
Spiral Arm

To investigate the interaction of the massive stars with the gas and dust in the active star forming region NGC 6357, located in the Sagittarius spiral arm at a distance of 1.7-2.6 kpc (Massey et al. 2001), we analyzed the distribution of the neutral and ionized gas, and that of the dust, based on Hα, [OIII] and [SII] images obtained with the Curtis-Schmidt telescope at CTIO, radio continuum observations at 1.465 MHz obtained with the Very Large Array (NRAO) in the DnC configuration (synthesized beam = 38″), Hi data from the Parkes survey (angular resolution = 15′), CO(1-0) observations obtained with the Nanten radiotelescope at Las Campanas Observatory (angular resolution = 2.7′), and IR images in the four MSX bands (angular resolution = 18.3″).

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 A Sub-arcsecond Study of Ionized Gas in NGC 253

2001 ◽  
Vol 205 ◽  
pp. 400-403
Author(s):  
K.R. Anantharamaiah ◽  
Niruj R. Mohan ◽  
W.M. Goss
Keyword(s):  
Mass Function ◽  
Star Cluster ◽  
Initial Mass Function ◽  
Radio Continuum ◽  
Starburst Galaxy ◽  
Large Array ◽  
Nuclear Region ◽  
Ionized Gas ◽  
Very Large Array ◽  
Stellar Density

The nuclear region of the starburst galaxy NGC 253 was observed in H92α (8.3 GHz) and H75α (15.4 GHz) recombination lines at sub-arcsecond resolution using the A-configuration of the Very Large Array (VLA). In the highest resolution observations at 15.3 GHz, we have detected a compact (< 5 pc), high density (> 5 × 104 cm−3) ionized region which is nearly coincident with the radio continuum peak near the nucleus. Modeling of RRL emission from this region shows that about 1000 O stars are needed to maintain the ionization. Assuming the Salpeter initial mass function, the implied overall stellar density corresponds to that of a super star cluster.

scholarly journals VLA Observations of Planetary Nebulae at the Galactic Centre

1983 ◽  
Vol 103 ◽  
pp. 423-424
Author(s):  
R. Gathier ◽  
S.R. Pottasch ◽  
W.M. Goss ◽  
J.H. van Gorkom
Keyword(s):  
New Mexico ◽  
Detection Limit ◽  
Selection Effect ◽  
Planetary Nebulae ◽  
Radial Velocities ◽  
Galactic Centre ◽  
Large Array ◽  
Very Large Array ◽  
Instrumental Resolution

The Very Large Array (VLA) in Socorro, New Mexico, has been used to measure the 6 cm continuum flux densities and the angular sizes of 42 planetary nebulae (PN) in the direction of the galactic centre (GC). These were all optically confirmed PN for which the radial velocities (and positions on the sky) make it very likely that they are close to the GC. With a detection limit of about 1 mJy, 34 PN were detected. Their flux densities range from 2 to 100 mJy. Initially we used a configuration of the VLA with an instrumental resolution of 1″. About 80% of the detected PN could be clearly resolved with this resolution. The unresolved PN were observed again with a configuration of the VLA that has a resolution of 0″.4. For all but one of the 34 detected PN we could determine reliable angular sizes. The inferred total ionized masses range from < 0.01 to ~ 0.5 M⊙, assuming a distance to the GC of 9 kpc. The results argue strongly against the use of the Shklovsky method for distance determinations. Previous measurements of PN at the GC showed that their luminosities were substantially higher than those for nearby PN (Pottasch, 1980). The luminosity distribution of the PN in our sample is broader towards lower luminosities (up to the detection limit of the observations), but the luminosities are still high compared with nearby PN. We interpret this as a selection effect: by studying only optically confirmed PN, the intrinsically brightest PN are selected.

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