scholarly journals CO line and radio continuum study of elephant trunks: the Pillars of Creation in M16

2020 ◽  
Vol 492 (4) ◽  
pp. 5966-5979 ◽  
Author(s):  
Yoshiaki Sofue
Keyword(s):  
Surface Brightness ◽  
Galactic Plane ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
Very Large Array ◽  
Heating Source ◽  
Velocity Gradients ◽  
Magnetic Oscillation ◽  
H Ii Region ◽  
Line Survey

ABSTRACT Molecular line and radio continuum properties of the elephant trunks (ET, Pillars of Creation) in M16 are investigated by analysing 12CO(J = 1−0) , 13CO(J = 1−0) and C18O(J = 1−0) line survey data from the Nobeyama 45-m telescope and the Galactic plane radio survey at 20 and 90 cm with the Very Large Array. The head clump of Pillar West I is found to be the brightest radio source in M16, showing a thermal spectrum and the properties of a compact H ii region, with the nearest O5 star in NGC 6611 being the heating source. The radio pillars have a cometary structure concave to the molecular trunk head, and the surface brightness distribution obeys a simple illumination law from a remote excitation source. The molecular density in the pillar head is estimated to be several 104 H2 cm−3 and the molecular mass is $\sim 13\!-\!40 \, \mathrm{M}_\odot$. CO-line kinematics reveals random rotation of the clumps in the pillar tail at ∼1–2 km s−1, comparable with the velocity dispersion and estimated Alfvén velocity. It is suggested that the random directions of the velocity gradients would manifest as torsional magnetic oscillation of the clumps around the pillar axis.

scholarly journals S201: The Ionized Skin of a Molecular Blob

1987 ◽  
Vol 115 ◽  
pp. 196-197
Author(s):  
M. Felli ◽  
R. Cesaroni ◽  
R. M. Hjellming
Keyword(s):  
Surface Brightness ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
East Side ◽  
Extended Component ◽  
H Ii Region

S201 is an optically visible H II region whose ionizing star is hidden to the sight by heavy obscuration. The radio continuum surface brightness distribution observed at 6-cm with the VLA can be described by two distinct components: a) an extended diffuse structure, which closely reproduces the shape of the observable nebulosity, and b) a sharp bright arc feature on the east side of the extended component, unresolved towards the outside at the resolution of ∼ 4″.

scholarly journals Characterizing the radio continuum nature of sources in the massive star-forming region W75N (B)

2020 ◽  
Vol 496 (3) ◽  
pp. 3128-3141 ◽  
Author(s):  
A Rodríguez-Kamenetzky ◽  
C Carrasco-González ◽  
J M Torrelles ◽  
W H T Vlemmings ◽  
L F Rodríguez ◽  
...  
Keyword(s):  
Massive Star ◽  
Radio Continuum ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Very Large Array ◽  
Star Forming ◽  
Thermal Radio ◽  
Wide Range ◽  
H Ii Region ◽  
Continuum Data

ABSTRACT The massive star-forming region W75N (B) is thought to host a cluster of massive protostars (VLA 1, VLA 2, and VLA 3) undergoing different evolutionary stages. In this work, we present radio continuum data with the highest sensitivity and angular resolution obtained to date in this region, using the VLA-A and covering a wide range of frequencies (4–48 GHz), which allowed us to study the morphology and the nature of the emission of the different radio continuum sources. We also performed complementary studies with multi-epoch Very Large Array (VLA) data and Atacama Large Millimeter Array (ALMA) archive data at 1.3 mm wavelength. We find that VLA 1 is driving a thermal radio jet at scales of ≈0.1 arcsec (≈130 au), but also shows signs of an incipient hypercompact H ii region at scales of ≲1 arcsec (≲1300 au). VLA 3 is also driving a thermal radio jet at scales of a few tenths of arcsec (few hundred of au). We conclude that this jet is shock exciting the radio continuum sources Bc and VLA 4 (obscured Herbig–Haro objects), which show proper motions moving outward from VLA 3 at velocities of ≈112–118 km s−1. We have also detected three new weak radio continuum sources, two of them associated with millimetre continuum cores observed with ALMA, suggesting that these two sources are also embedded young stellar objects in this massive star-forming region.

scholarly journals Ultracompact H ii regions with extended emission: the complete view

2019 ◽  
Vol 492 (1) ◽  
pp. 895-914 ◽  
Author(s):  
Eduardo de la Fuente ◽  
Alicia Porras ◽  
Miguel A Trinidad ◽  
Stanley E Kurtz ◽  
Simon N Kemp ◽  
...  
Keyword(s):  
Morphological Study ◽  
Galactic Plane ◽  
Radio Continuum ◽  
H Ii Regions ◽  
Direct Connection ◽  
Infrared Excess ◽  
Very Large Array ◽  
Bubble Structure ◽  
Colour Composite ◽  
Extended Emission

ABSTRACT In this paper, we present the results of a morphological study performed on a sample of 28 ultracompact H ii (UC H ii) regions located near extended free–free emission, using radio continuum (RC) observations at 3.6 cm with the C and D Very Large Array (VLA) configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA configurations, we compiled a final catalogue of 21 UC H ii regions directly connected with the surrounding extended emission (EE). The observed morphology of most of the UC H ii regions in RC emission is irregular (single- or multipeaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. RC images superimposed on colour composite Spitzer images reinforce the assignations of direct connection by the spatial coincidence between the UC components and regions of saturated 24 μm emission. We also find that the presence of EE may be crucial to understand the observed infrared excess because an underestimation of ionizing Lyman photons was considered in previous works (e.g. Wood & Churchwell; Kurtz, Churchwell & Wood).

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 MON R2: A Blister Type H II Region

1987 ◽  
Vol 115 ◽  
pp. 193-193
Author(s):  
M. Massi ◽  
M. Felli ◽  
M. Catarzi ◽  
M. Simon
Keyword(s):  
Surface Brightness ◽  
Brightness Distribution ◽  
Circular Shape ◽  
H Ii Region

The compact H II region MONR2 has been studied with the VLA at 6 and 1.3 cm (Massi, Felli, and Simon 1985). With a resolution of 1″ the source is now well resolved. The H II region has a circular shape 27″ in diameter and a non uniform surface brightness distribution. The peak of the emission is concentrated in a small sharp strip along the SE edge.

scholarly journals Discovery of a New Population of Galactic H ii Regions with Ionized Gas Velocity Gradients

2021 ◽  
Vol 921 (2) ◽  
pp. 176
Author(s):  
Dana S. Balser ◽  
Trey V. Wenger ◽  
L. D. Anderson ◽  
W. P. Armentrout ◽  
T. M. Bania ◽  
...  
Keyword(s):  
Solid Body ◽  
Galactic Plane ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
H Ii Regions ◽  
Very Large Array ◽  
Bipolar Outflow ◽  
Velocity Gradients ◽  
Independent Observations ◽  
Many Sources

Abstract We investigate the kinematic properties of Galactic H ii regions using radio recombination line (RRL) emission detected by the Australia Telescope Compact Array at 4–10 GHz and the Jansky Very Large Array at 8–10 GHz. Our H ii region sample consists of 425 independent observations of 374 nebulae that are relatively well isolated from other, potentially confusing sources and have a single RRL component with a high signal-to-noise ratio. We perform Gaussian fits to the RRL emission in position-position–velocity data cubes and discover velocity gradients in 178 (42%) of the nebulae with magnitudes between 5 and 200 m s − 1 arcsec − 1 . About 15% of the sources also have an RRL width spatial distribution that peaks toward the center of the nebula. The velocity gradient position angles appear to be random on the sky with no favored orientation with respect to the Galactic plane. We craft H ii region simulations that include bipolar outflows or solid body rotational motions to explain the observed velocity gradients. The simulations favor solid body rotation since, unlike the bipolar outflow kinematic models, they are able to produce both the large, >40 m s − 1 arcsec − 1 , velocity gradients and also the RRL width structure that we observe in some sources. The bipolar outflow model, however, cannot be ruled out as a possible explanation for the observed velocity gradients for many sources in our sample. We nevertheless suggest that most H ii region complexes are rotating and may have inherited angular momentum from their parent molecular clouds.

scholarly journals HCO+and Radio Continuum Emission from the Star Forming Region G75.78+0.34

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Rogemar A. Riffel ◽  
Everton Lüdke
Keyword(s):  
Massive Star ◽  
Emission Measure ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Ionized Gas ◽  
Very Large Array ◽  
Star Forming ◽  
Molecular Outflows ◽  
H Ii Region ◽  
The Continuum

We present 1.3 and 3.6 cm radio continuum images and a HCO+spectrum of the massive star forming region G75.78+0.34 obtained with the Very Large Array (VLA) and with the Berkley Illinois Maryland Association (BIMA) interferometer. Three structures were detected in the continuum emission: one associated with the well-known cometary H ɪɪ region, plus two more compact structures located at 6′′ east and at 2′′ south of cometary H ɪɪ region. Using the total flux and intensity peak we estimated an electron density of≈1.5 × 104 cm−3, an emission measure of≈6 × 107 cm−6 pc, a mass of ionized gas of≈3 M⊙, and a diameter of 0.05 pc for the cometary H ɪɪ region, being typical values for an ultracompact H ɪɪ region. The HCO+emission probably originates from the molecular outflows previously observed in HCN and CO.

scholarly journals A Giant Stellar-Wind Shell and Star Formation Near the H II Region M16

1987 ◽  
Vol 115 ◽  
pp. 194-196
Author(s):  
Y. Sofue ◽  
T. Handa ◽  
E. Fürst ◽  
W. Reich ◽  
P. Reich
Keyword(s):  
Star Formation ◽  
Electron Density ◽  
Thermal Energy ◽  
Stellar Wind ◽  
Galactic Plane ◽  
Radio Continuum ◽  
Gray Scale ◽  
H Ii Region ◽  
The Mean ◽  
Total Thermal Energy

A large radio continuum loop of diameter was discovered at G16.5+0.7 on the Bonn 2.7 GHz and NRO 10 GHz galactic plane surveys. The loop is associated with the H II region M16, and the diameter is 60 pc at a distance of 2.8 kpc. Figure 1 shows the loop at 2.7 GHz in gray scale. The spectrum is thermal and the total H II mass is estimated at 3×103 M⊙. If the loop is due to a shell of the same diameter, the mean electron density on the shell is about 4 cm−3. The total thermal energy is about 6×1048ergs. The characteristics are summarized in Table 1.

scholarly journals Ultracompact H ii regions with extended emission: the case of G43.89–0.78 and its molecular environment

2020 ◽  
Vol 497 (4) ◽  
pp. 4436-4447
Author(s):  
Eduardo de la Fuente ◽  
Daniel Tafoya ◽  
Miguel A Trinidad ◽  
Alicia Porras ◽  
Alberto Nigoche-Netro ◽  
...  
Keyword(s):  
Operational Definition ◽  
Radio Continuum ◽  
Physical Parameters ◽  
Kinetic Temperature ◽  
H Ii Regions ◽  
Owens Valley ◽  
Very Large Array ◽  
Compact Component ◽  
H Ii Region ◽  
Extended Emission

ABSTRACT The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory (OVRO), Atacama Large Millimetric Array (ALMA), and the infrared Spitzer observatories are powerful facilities to study massive star formation regions and related objects such as ultra-compact (UC) H ii regions, molecular clumps, and cores. We used these telescopes to study the UC H ii region G43.89–0.78. The morphological study at arcminute scales using NVSS and Spitzer data shows that this region is similar to those observed in the bubble-like structures revealed by Spitzer observations. With this result, and including a physical characterization based on 3.6 cm data, we suggest G43.89–0.78 be classified as an UC H ii region with Extended Emission because it meets the operational definition given in this paper comparing radio continuum data at 3.6 and 20 cm. For the ultra-compact component, we use VLA data to obtain physical parameters at 3.6 cm confirming this region as an UC H ii region. Using ALMA observations, we detect the presence of a dense (2.6 × 107 cm−3) and small (∼ 2.0 arcsec; 0.08 pc) molecular clump with a mass of 220 M⊙ and average kinetic temperature of 21 K, located near to the UC H ii region. In this clump, catalogued as G43.890–0.784, water masers also exist, possibly tracing a bipolar outflow. We discover in this vicinity two additional clumps which we label as G43.899–0.786 (Td = 50 K; M  = 11 M⊙) and G43.888–0.787 (Td = 50 K; M  = 15 M⊙).

Simulated synchrotron emission for the Tycho’s supernova remnants: an asymmetric initial mass model

2020 ◽  
Vol 494 (2) ◽  
pp. 1531-1538
Author(s):  
A Moranchel-Basurto ◽  
P F Velázquez ◽  
G Ares de Parga ◽  
E M Reynoso ◽  
E M Schneiter ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
Initial Mass ◽  
Continuum Emission ◽  
Synchrotron Emission ◽  
Mass Model ◽  
Mhd Simulations ◽  
Tycho’S Snr ◽  
Good Agreement

ABSTRACT We have performed 3D magnetohydrodynamics (MHD) numerical simulations with the aim of exploring the scenario in which the initial mass distribution of a supernova (SN) explosion is anisotropic. The purpose is to analyse if this scenario can also explain the radio-continuum emission and the expansion observed in young supernova remnants (SNRs). To study the expansion, synthetic polarized synchrotron emission maps were computed from the MHD simulations. We found a good agreement (under a number of assumptions) between this expansion study and previous observational results applied to Tycho’s SNR, which represents a good example of asymmetric young SNRs. Additionally, both the observed morphology and the brightness distribution are qualitatively reproduced.

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