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1171. OH megamasers at z>0.1. III
ID:
ivo://CDS.VizieR/J/AJ/124/100
Title:
OH megamasers at z>0.1. III
Short Name:
J/AJ/124/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final results from the Arecibo Observatory OH megamaser survey. We discuss in detail the properties of the remaining 18 OH megamasers detected in the survey, including three redetections. We place upper limits on the OH emission from 85 nondetections and examine the properties of 25 ambiguous cases for which the presence or absence of OH emission could not be determined. The complete survey has discovered 50 new OH megamasers (OHMs) in (ultra)luminous infrared galaxies ([U]LIRGs), which doubles the sample of known OHMs and increases the sample at z>0.1 sevenfold.
1172. OH megamasers infrared photometry
ID:
ivo://CDS.VizieR/J/AJ/133/496
Title:
OH megamasers infrared photometry
Short Name:
J/AJ/133/496
Date:
21 Oct 2021
Publisher:
CDS
Description:
OH megamasers are the most luminous masers in the universe. The total of 109 OH megamaser (OHM) galaxies known so far have been collected, and cross-identifications of those OHM galaxies with Two Micron All Sky Survey (2MASS) sources are made in this paper. Using 2MASS (Cat. II/246) and IRAS (Cat. II/125, II/156) data, the infrared properties of OHM-detected and non-detected sources are compared.
1173. OH 6035MHz line in high-mass SFRs
ID:
ivo://CDS.VizieR/J/A+A/642/A145
Title:
OH 6035MHz line in high-mass SFRs
Short Name:
J/A+A/642/A145
Date:
21 Oct 2021
Publisher:
CDS
Description:
The excited states of OH masers detected in the environment of high-mass young stellar objects (HMYSOs) are important for improving our understanding of the physical conditions of these objects and also provide information about their magnetic fields. We aim to search for excited-state OH 6035MHz maser emission in HMYSOs which might have escaped detection in previous surveys or were never searched for. Methods. A sample of HMYSOs derived from untargeted surveys of the 6668MHz methanol maser line was observed at 6035MHz OH transition with the Torun 32m radio telescope. The 6035MHz detections were observed in the OH 6031MHz line. Two-thirds of the detections were observed at least three times over a two-year period. Out of 445 targets, 37 were detected at 6035MHz, including seven new discoveries. The 6031MHz line was detected towards ten 6035MHz sources, one of which was not previously reported. All the newly detected sources are faint with the peak flux density lower than 4Jy and show significant or high variability on timescales of 4 to 20 months. Zeeman pair candidates identified in three new sources imply a magnetic field intensity of 2-11mG. Comparison of our spectra with those obtained ~10yr ago indicates different degrees of variability but there is a general increase in the variability index on an ~25yr timescale, usually accompanied by significant changes in the profile shape.
1174. OH observations of Arecibo OH/IR stars
ID:
ivo://CDS.VizieR/J/ApJS/109/489
Title:
OH observations of Arecibo OH/IR stars
Short Name:
J/ApJS/109/489
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Arecibo 1612MHz survey of a complete sample of color-selected IRAS sources with 25{mu}m fluxes S(25)>2 Jy detected 393 OH/IR stars. A complementary 1667 and 1665MHz OH survey of these objects is presented here. Main-line masers have been detected in 238 surveyed objects: 18 exhibit only 1665MHz emission, 220 exhibit 1667MHz masers, and 119 exhibit both. The main lines were not detected in 159 objects.
1175. OH-selected AGB and post-AGB objects. I.
ID:
ivo://CDS.VizieR/J/AJ/123/2772
Title:
OH-selected AGB and post-AGB objects. I.
Short Name:
J/AJ/123/2772
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using 766 compact objects found in a systematic survey of the Galactic plane in the 1612MHz masing OH line, new light is cast on the IR properties of evolved stars on the thermally pulsing asymptotic giant branch (AGB) and beyond. The usual mid-IR selection criteria for post-AGB, based on IRAS colors, largely fail to distinguish early post-AGB stages. A two-color diagram from much narrower band MSX flux densities, with bimodal distributions, provides a better tool for doing this. Four mutually consistent selection criteria for OH-masing red protoplanetary nebulae are given, as well as two for early post-AGB masers and one for all post-AGB masers including the earliest ones. All these criteria miss a group of blue, high-outflow post-AGB sources with 60{mu}m excess; these will be discussed in detail in Paper II (Sevenster, 2002AJ....123.2772S). The majority of post-AGB sources show regular double-peaked spectra in the OH 1612MHz line, with fairly low outflow velocities, although the fractions of single peaks and irregular spectra may vary with age and mass. The OH flux density shows a fairly regular relation with the stellar flux and the envelope optical depth, with the maser efficiency increasing with IRAS color R_21_. The OH flux density is linearly correlated with the 60{mu}m flux density.
1176. OMC 1 reduced H_2_CO(3-2) datacubes
ID:
ivo://CDS.VizieR/J/A+A/609/A16
Title:
OMC 1 reduced H_2_CO(3-2) datacubes
Short Name:
J/A+A/609/A16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We mapped the kinetic temperature structure of the Orion molecular cloud 1 (OMC-1) with para-H_2_CO(J_KaKc_=3_03_-2_02_, 3_22_-2_21_, and 3_21_-2_20_) using the APEX 12m telescope. This is compared with the temperatures derived from the ratio of the NH_3_ (2,2)/(1,1) inversion lines and the dust emission. Using the RADEX non-LTE model, we derive the gas kinetic temperature modeling the measured averaged line ratios of para-H_2_CO 3_22_-2_21_/3_03_-2_02_ and 3_21_-2_20_/3_03_-2_02_. The gas kinetic temperatures derived from the para-H_2_CO line ratios are warm, ranging from 30 to >200K with an average of 62+/-2K at a spatial density of 10^5^cm^-3^. These temperatures are higher than those obtained from NH_3_ (2,2)/(1,1) and CH_3_CCH(6-5) in the OMC-1 region. The gas kinetic temperatures derived from para-H_2_CO agree with those obtained from warm dust components measured in the mid infrared (MIR), which indicates that the para-H_2_CO(3-2) ratios trace dense and warm gas. The cold dust components measured in the far infrared (FIR) are consistent with those measured with NH_3_ (2,2)/(1,1) and the CH_3_CCH(6-5) line series. With dust at MIR wavelengths and para-H_2_CO(3-2) on one side and dust at FIR wavelengths, NH_3_ (2,2)/(1,1), and CH_3_CCH(6-5) on the other, dust and gas temperatures appear to be equivalent in the dense gas (n(H_2_)>~10^4^cm^-3^) of the OMC-1 region, but provide a bimodal distribution, one more directly related to star formation than the other. The non-thermal velocity dispersions of para-H2CO are positively correlated with the gas kinetic temperatures in regions of strong non-thermal motion (Mach number >~2.5) of the OMC-1, implying that the higher temperature traced by para-H2CO is related to turbulence on a ~0.06pc scale. Combining the temperature measurements with para-H_2_CO and NH3 (2,2)/(1,1) line ratios, we find direct evidence for the dense gas along the northern part of the OMC-1 10km/s filament heated by radiation from the central Orion nebula.
1177. 16O18O isotopomer collision rate
ID:
ivo://CDS.VizieR/J/A+A/328/617
Title:
16O18O isotopomer collision rate
Short Name:
J/A+A/328/617
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, a chemical model of interstellar clouds including ^18^O and ^13^C isotopic reactions with a non-LTE calculations of ^16^O^18^O rotational population has been used to predict the intensity of the three ^16^O^18^O lines observable from the ground, namely 234, 298 and 402GHz.
1178. Oph A mosaic image
ID:
ivo://CDS.VizieR/J/A+A/631/A58
Title:
Oph A mosaic image
Short Name:
J/A+A/631/A58
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity, which are intimately connected to the evolution of protoplanetary disks and the formation of planets. We have carried out sensitive continuum observations toward the Ophiuchus A star-forming region using the Karl G. Jansky Very Large Array (VLA) at 10GHz over a field-of-view of 6' with a spatial resolution of {theta}_maj_x{theta}_min_~0.4"x0.2". We achieved a 5{mu}Jy/beam root-mean-square noise level at the center of our mosaic field of view. Among the eighteen sources we detected, sixteen are YSOs (three Class 0, five Class I, six Class II, and two Class III) and two are extragalactic candidates.We find that thermal dust emission generally contributes less that 30% of the emission at 10GHz. The radio emission is dominated by other types of emission such as gyro-synchrotron radiation from active magnetospheres, free-free emission from thermal jets, free-free emission from the outflowing photo-evaporated disk material, and/or synchrotron emission from accelerated cosmic-rays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our non-detections towards Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain the disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolve with time. The sensitivity of our data cannot exclude photoevaporation due to X-ray photons as an efficient mechanism for disk dispersal. Deeper surveys with the Square Kilometre Array will be able to provide strong constraints on disk photoevaporation.
1179. Optical and radio data for rich Abell clusters
ID:
ivo://CDS.VizieR/J/AJ/126/119
Title:
Optical and radio data for rich Abell clusters
Short Name:
J/AJ/126/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical observations and radio continuum imaging data for a sample of rich, X-ray-bright Abell clusters at intermediate (z~0.2) redshifts. We find that the radio galaxy population varies substantially from cluster to cluster within this homogeneous sample. The spatial distribution of the high-luminosity radio galaxies (HLRGs; L1.4>10^23^W/Hz) is very different from the low-luminosity radio galaxies (LLRGs; L1.4<=10^22.75^W/Hz), with the LLRGs displaying a flat spatial distribution in contrast to the centrally peaked HLRGs. A color-morphology classification shows that the HLRGs are composed primarily of galaxies with old stellar populations, whereas the LLRGs have a much more diverse composition. We do not see a correlation between the cluster radio fraction and cluster blue fraction. However, there is a moderate anticorrelation with richness, suggesting that a rich cluster is less likely to have radio-bright galaxies, whether the radio emission is due to active galactic nuclei or star formation.
1180. Optical astrometry of Benchmark radio sources. III
ID:
ivo://CDS.VizieR/J/A+AS/115/75
Title:
Optical astrometry of Benchmark radio sources. III
Short Name:
J/A+AS/115/75
Date:
21 Oct 2021
Publisher:
CDS
Description:
Optical positions, relative to the International Reference Stars catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 35 extragalactic radio sources south of {delta}~+3deg. Many of these sources are being considered as possible Benchmark objects for the establishment of a quasi-inertial unified radio/optical reference frame. Precision levels better than 0.2" in both coordinates were achieved. A comparison with VLBI radio positions available for these sources is presented. We give evidence for a possible offset in RA between the radio and optical reference frames.