scholarly journals High-velocity Wind from IRS 1 in the NGC 2071IR

2014 ◽  
Vol 10 (S305) ◽  
pp. 301-304
Author(s):  
Miguel Angel Trinidad
Keyword(s):  
High Velocity ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Central Source ◽  
Star Forming ◽  
The North ◽  
Infrared Sources ◽  
The Impact ◽  
Water Maser ◽  
East West

AbstractWe present the results of 1.3 and 3.6 cm radio continuum emission toward the NGC 2071IR star-forming region, carried out with the VLA in its A configuration. We detect continuum emission toward the infrared sources IRS 1 and IRS 3 at both wavelengths. In particular, IRS 1 breaks up into three continuum peaks (IRS 1E, 1C, and 1W), aligned in the east-west direction, being IRS 1 the central source. The morphology of the condensation IRS 1W is very interesting, which has an elongated structure and shows a significant curvature towards the north. We suggest that this morphology could be explained as the impact of a high-velocity wind or jetlike outflow from IRS 1 on a close companion or other obstruction, which also explains the strong water maser emission observed toward IRS 1W.

scholarly journals A Highly-collimated Water Maser Bipolar Outflow in the Cepheus A HW3d Massive Protostellar Object

2012 ◽  
Vol 8 (S287) ◽  
pp. 141-145
Author(s):  
James O. Chibueze ◽  
Hiroshi Imai ◽  
Daniel Tafoya ◽  
Toshihiro Omodaka ◽  
Osamu Kameya ◽  
...  
Keyword(s):  
Strong Support ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Very Large Array ◽  
Star Forming ◽  
Bipolar Outflow ◽  
Long Baseline ◽  
Cepheus A ◽  
Continuum Data ◽  
Water Maser

AbstractWe report the results of multi-epoch very long baseline interferometry (VLBI) water (H2O) maser observations carried out with the VLBI Exploration of Radio Astrometry (VERA) toward the HW3d object within the Cepheus A star-forming region. We measured proper motions of 30 water maser features, tracing a compact bipolar outflow. This outflow is highly collimated, extending through ~400 mas (290 AU), and having a typical proper motion velocity of ~6 mas yr−1 (~21 km s−1). The dynamical timescale of the outflow was estimated to be ~100 years, showing that the outflow is tracing a very early star-formation phase. Our results provide strong support that the HW3d object harbors an internal massive protostar, as previous observations suggested. In addition, we have analyzed Very Large Array (VLA) archive 1.3 cm continuum data of the 1995 and 2006 epochs obtained towards Cepheus A. These results indicate possible different protostars around HW3d and/or strong variability in its radio continuum emission.

scholarly journals A search for water maser emission from post-AGB stars

2007 ◽  
Vol 3 (S242) ◽  
pp. 287-291
Author(s):  
J. M. Chapman ◽  
R. M. Deacon ◽  
A. J. Green ◽  
M. Cohen
Keyword(s):  
High Velocity ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Agb Stars ◽  
Maser Emission ◽  
Evolved Stars ◽  
Thermal Radio ◽  
Water Maser

AbstractWe have used the Tidbinbilla 70-m antenna to search for 22 GHz H2O maser emission from a sample of 85 evolved stars. 21 detections were made. Of these 15 were from massive AGB stars. High-velocity H2O maser emission was detected from five sources, of which four are post-AGB stars. Three of the high-velocity sources, b292 (IRAS 18043–2116), d46 (IRAS 15445–5449), and d62 (IRAS 15544–5332) were new discoveries. d46 is also a source of non-thermal radio continuum emission. The high-velocity H2O maser emission and the radio continuum from post-AGB stars are probably associated with shocks that form from wind-wind interactions.

scholarly journals Near-Infrared Sources in the Complex H II Region NGC 6357

1987 ◽  
Vol 115 ◽  
pp. 187-188
Author(s):  
P. Persi ◽  
M. Ferrari-Toniolo ◽  
M. Roth ◽  
M. Tapia
Keyword(s):  
Near Infrared ◽  
Baja California ◽  
Infrared Emission ◽  
Radio Continuum ◽  
Star Forming ◽  
H Ii Region ◽  
Infrared Sources ◽  
Near Infrared Emission ◽  
Water Maser

We have searched for the near-infrared emission from selected areas of the star forming region NGC 6357. Six fields of 90x90 arcsec2 centered on the far-IR peaks G353.19+0.91, G353.22+0.67, G353.13+0.64, G353.05+0.56, on the 6-cm radio continuum peak G353.035+0.78, and on the water maser source H20353.27+0.64, were scanned through the K(2.2 μm) filter at the 2.1-m telescope of the Observatorio Astronómico Nacional at S. Pedro Mártir, Baja California, México.

scholarly journals Radio continuum size evolution of star-forming galaxies over 0.35 < z < 2.25

2019 ◽  
Vol 625 ◽  
pp. A114 ◽  
Author(s):  
E. F. Jiménez-Andrade ◽  
B. Magnelli ◽  
A. Karim ◽  
G. Zamorani ◽  
M. Bondi ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Gaussian Model ◽  
Cosmic Time ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Selection Function ◽  
Star Forming ◽  
Size Evolution ◽  
Galaxy Population

To better constrain the physical mechanisms driving star formation, we present the first systematic study of the radio continuum size evolution of star-forming galaxies (SFGs) over the redshift range 0.35 <  z <  2.25. We use the VLA COSMOS 3 GHz map (noise rms = 2.3 μJy beam−1, θbeam = 0.75 arcsec) to construct a mass-complete sample of 3184 radio-selected SFGs that reside on and above the main sequence (MS) of SFGs. We constrain the overall extent of star formation activity in galaxies by applying a 2D Gaussian model to their radio continuum emission. Extensive Monte Carlo simulations are used to validate the robustness of our measurements and characterize the selection function. We find no clear dependence between the radio size and stellar mass, M⋆, of SFGs with 10.5 ≲ log(M⋆/M⊙) ≲ 11.5. Our analysis suggests that MS galaxies are preferentially extended, while SFGs above the MS are always compact. The median effective radius of SFGs on (above) the MS of Reff = 1.5 ± 0.2 (1.0 ± 0.2) kpc remains nearly constant with cosmic time; a parametrization of the form Reff ∝ (1 + z)α yields a shallow slope of only α = −0.26 ± 0.08 (0.12 ± 0.14) for SFGs on (above) the MS. The size of the stellar component of galaxies is larger than the extent of the radio continuum emission by a factor ∼2 (1.3) at z = 0.5 (2), indicating star formation is enhanced at small radii. The galactic-averaged star formation rate surface density (ΣSFR) scales with the distance to the MS, except for a fraction of MS galaxies (≲10%) that harbor starburst-like ΣSFR. These “hidden” starbursts might have experienced a compaction phase due to disk instability and/or a merger-driven burst of star formation, which may or may not significantly offset a galaxy from the MS. We thus propose to use ΣSFR and distance to the MS in conjunction to better identify the galaxy population undergoing a starbursting phase.

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.

A new jet/outflow maser in the nucleus of the Compton-thick AGN IRAS 15480-0344

2017 ◽  
Vol 13 (S336) ◽  
pp. 129-132
Author(s):  
Paola Castangia ◽  
Andrea Tarchi ◽  
Alessandro Caccianiga ◽  
Paola Severgnini ◽  
Gabriele Surcis ◽  
...  
Keyword(s):  
Detection Rate ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Maser Emission ◽  
X Ray ◽  
Vlbi Observations ◽  
S0 Galaxies ◽  
Water Maser

AbstractInvestigations of H2O maser galaxies at X-ray energies reveal that most harbor highly absorbed AGN. Possible correlations between the intrinsic X-ray luminosity and the properties of water maser emission have been suggested. With the aim of looking into these correlations on a more solid statistical basis, we have search for maser emission in a well-defined sample of Compton-thick AGN. Here we report the results of the survey, which yielded a surprisingly high maser detection rate, with a particular focus on the newly discovered luminous water maser in the lenticular (field) S0 galaxy IRAS 15480-0344. Recently, VLBI observations have been obtained to image the line and continuum emission in the nucleus of this galaxy. The radio continuum emission at VLBI scales is resolved into two compact components that are interpreted as jet knots. Based on the single-dish profile, the variability of the maser emission, and the position of the maser spots with respect to these continuum sources, we favor of a jet/outflow origin for the maser emission, consistent with similar cases found in other radio-quiet AGN. This scenario is consistent with the hypothesis of the presence of strong nuclear winds recently invoked to explain the main characteristics of field S0 galaxies.

Water masers as signposts of extremely young planetary nebulae

2017 ◽  
Vol 13 (S336) ◽  
pp. 377-380
Author(s):  
José F. Gómez ◽  
Luis F. Miranda ◽  
Lucero Uscanga ◽  
Olga Suárez
Keyword(s):  
Planetary Nebulae ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Water Masers ◽  
Water Maser

AbstractOnly five planetary nebulae (PNe) have been confirmed to emit water masers. They seem to be very young PNe. The water emission in these objects preferentially traces circumstellar toroids, although in K 3-35 and IRAS 15103-5754, it may also trace collimated jets. We present water maser observations of these two sources at different epochs. The water maser distribution changes on timescales of months to a few years. We speculate that these changes may be due to the variation of the underlying radio continuum emission, which is amplified by the maser process in the foreground material.

scholarly journals Observational constraints on dust disk sizes in tidally truncated protoplanetary disks in multiple systems in the Taurus region

2019 ◽  
Vol 628 ◽  
pp. A95 ◽  
Author(s):  
C. F. Manara ◽  
M. Tazzari ◽  
F. Long ◽  
G. J. Herczeg ◽  
G. Lodato ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Protoplanetary Disks ◽  
Mass Range ◽  
Outer Radius ◽  
Continuum Emission ◽  
Stellar Systems ◽  
Multiple Systems ◽  
Star Forming ◽  
Dust Disk ◽  
The Impact

The impact of stellar multiplicity on the evolution of planet-forming disks is still the subject of debate. Here we present and analyze disk structures around ten multiple stellar systems that were included in an unbiased, high spatial resolution survey performed with ALMA of 32 protoplanetary disks in the Taurus star-forming region. At the unprecedented spatial resolution of ~0.12′′ we detect and spatially resolve the disks around all primary stars, and those around eight secondary and one tertiary star. The dust radii of disks around multiple stellar systems are smaller than those around single stars in the same stellar mass range and in the same region. The disks in multiple stellar systems also show a steeper decay of the millimeter continuum emission at the outer radius than disks around single stars, suggestive of the impact of tidal truncation on the shape of the disks in multiple systems. However, the observed ratio between the dust disk radii and the observed separation of the stars in the multiple systems is consistent with analytic predictions of the effect of tidal truncation only if the eccentricities of the binaries are rather high (typically >0.5) or if the observed dust radii are a factor of two smaller than the gas radii, as is typical for isolated systems. Similar high-resolution studies targeting the gaseous emission from disks in multiple stellar systems are required to resolve this question.

scholarly journals Extreme gas kinematics in an off-nuclear HII region of SDSS J143245.98+404300.3

2019 ◽  
Vol 630 ◽  
pp. A124
Author(s):  
Bruno Rodríguez Del Pino ◽  
Santiago Arribas ◽  
Javier Piqueras López ◽  
Alejandro Crespo Gómez ◽  
José M. Vílchez
Keyword(s):  
High Velocity ◽  
Stellar Winds ◽  
Hii Region ◽  
Star Forming ◽  
Spectral Signatures ◽  
Gas Kinematics ◽  
Spatially Resolved ◽  
Broad Emission ◽  
The Impact ◽  
Gas Component

We present and discuss the properties of an ionized gas component with extreme kinematics in a recently reported off-nuclear HII region located at ∼0.8−1.0 kpc from the nucleus of SDSS J143245.98+404300.3. The high-velocity-gas component is identified by the detection of very broad emission wings in the Hα line, with full width at half maximum (FWHM)  ≥ 850−1000 km s−1. Such gas kinematics are outstandingly high compared to other HII regions in local galaxies and are similar to those reported in some star-forming clumps of galaxies at z ∼ 2. The spatially resolved analysis indicates that the high-velocity gas extends at least ∼90 pc and it could be compatible with an ionized outflow entraining gas at a rate between approximately seven and nine times faster than the rate at which gas is being converted into stars. We do not detect broad emission wings in other emission lines such as Hβ, perhaps due to moderate dust extinction, nor in [N II]λλ6548, 6584 or [S II]λλ6717, 6731, which could be due to the presence of turbulent mixing layers originated by the impact of fast-flowing winds. The lack of spectral signatures associated to the presence of Wolf–Rayet stars points towards stellar winds from a large number of massive stars and/or supernovae as the likely mechanisms driving the high-velocity gas.

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⊙).

Sign in / Sign up

Export Citation Format

Share Document