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Start Over Subject radio astronomy Publisher CDS
1461. Rest frequencies of dithioformic acid
ID:
ivo://CDS.VizieR/J/A+A/612/A56
Title:
Rest frequencies of dithioformic acid
Short Name:
J/A+A/612/A56
Date:
21 Oct 2021
Publisher:
CDS
Description:
A better understanding of sulphur chemistry is needed to solve the interstellar sulphur depletion problem. A way to achieve this goal is to study new S-bearing molecules in the laboratory, obtaining accurate rest frequencies for an astronomical search. We focus on dithioformic acid, HCSSH, which is the sulphur analogue of formic acid. The aim of this study is to provide an accurate line list of the two HCSSH trans and cis isomers in their electronic ground state and a comprehensive centrifugal distortion analysis with an extension of measurements in the millimetre and submillimetre range. We studied the two isomers in the laboratory using an absorption spectrometer employing the frequency-modulation technique. The molecules were produced directly within a free-space cell by glow discharge of a gas mixture. We measured lines belonging to the electronic ground state up to 478GHz, with a total number of 204 and 139 new rotational transitions, respectively, for trans and cis isomers. The final dataset also includes lines in the centimetre range available from literature. The extension of the measurements in the mm and submm range lead to an accurate set of rotational and centrifugal distortion parameters. This allows us to predict frequencies with estimated uncertainties as low as 5kHz at 1mm wavelength. Hence, the new dataset provided by this study can be used for astronomical search.
1462. Rest frequencies of methanol maser lines
ID:
ivo://CDS.VizieR/J/A+A/428/1019
Title:
Rest frequencies of methanol maser lines
Short Name:
J/A+A/428/1019
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report accurate laboratory measurements of selected methanol transition frequencies between 0.834 and 230GHz in order to facilitate astronomical velocity analyses. New data have been obtained between 10 and 27GHz and between 60 and 119GHz. Emphasis has been put on known or potential interstellar maser lines as well as on transitions suitable for the investigation of cold dark clouds. Because of the narrow line widths (<0.5km/s) of maser lines and lines detected in dark molecular clouds, accurate frequencies are needed for comparison of the velocities of different methanol lines with each other as well as with lines from other species. In particular, frequencies for a comprehensive set of transitions are given which, because of their low energy levels (<20cm^-1^ or 30K), are potentially detectable in cold clouds. Global Hamiltonian fits generally do not yet yield the required accuracy. Additionally, we report transition frequencies for other lines that may be used to test and to improve existing Hamiltonian models.
1463. Revised GB/GB2 sample of radio sources
ID:
ivo://CDS.VizieR/J/A+AS/128/153
Title:
Revised GB/GB2 sample of radio sources
Short Name:
J/A+AS/128/153
Date:
21 Oct 2021
Publisher:
CDS
Description:
The revised sample of 373 extragalactic radio sources brighter than 0.2 Jy at 1.4GHz is presented. These sources, selected from the finding Green Bank surveys, were mapped at 1465 MHz using the VLA at different configurations. The biases introduced into the original GB (Maslowski, 1972AcA....22..227M) and GB2 (Machalski, 1978AcA....28..367M) catalogues by confusion as well as partial resolution by the VLA at its A-configuration, are eliminated. In effect, a number of sources have been excluded, and a few other are included into the revised sample. Now the sample is about 99, 97 and 95 per cent complete for sources with S_1.4_>=0.55Jy, 0.25Jy<=S_1.4_<0.55Jy, and 0.2Jy<=S_1.4_<0.25Jy, respectively. Table 3 gives the compilation of the radio, optical, and X-ray data available for the sample sources.
1464. Revised source list for the Rees 38-MHz survey
ID:
ivo://CDS.VizieR/VIII/31
Title:
Revised source list for the Rees 38-MHz survey
Short Name:
VIII/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a revised machine-readable source list for the Rees 38-MHz (or '8C') survey with improved positions and no redundancy. The Rees 38-MHz survey covers an area of about 1 sr north of declination +60 degrees. The angular resolution is 4.5 x 4.5cosec(Dec) arcmin**2 and the limiting flux density over much of the survey area is about 1 Jy. Both of these figures are an improvement by nearly an order of magnitude on previous surveys at this frequency. Users of these data should consult and cite the original survey paper by Rees as primary reference (1990MNRAS.244..233R) with the present publication (1995MNRAS.274..447H) as a supplementary revision. The recommended style of reference is thus : "The revised Rees 38-MHz survey (Rees 1990, catalogue revised Hales et. al 1995)." Note that for interest the source list includes data on some sources at declinations lower than +60 degrees, but that the right ascension coverage is not complete below +60 degrees.
1465. RMS compact HII regions distances
ID:
ivo://CDS.VizieR/J/MNRAS/420/1656
Title:
RMS compact HII regions distances
Short Name:
J/MNRAS/420/1656
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high-resolution HI data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact HII regions from the Red MSX Source (RMS) survey. The high-resolution data are complemented with lower resolution archival HI data extracted from the Southern and Very Large Array (VLA) Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the HI absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1000 massive young stellar objects and compact HII regions is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined.
1466. RMS survey
ID:
ivo://CDS.VizieR/J/MNRAS/452/4029
Title:
RMS survey
Short Name:
J/MNRAS/452/4029
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of ammonia observations towards 66 massive star forming regions identified by the Red Midcourse Space Experiment Source survey. We have used the Green Bank Telescope and the K-Band Focal Plane Array to map the ammonia (NH_3_) (1,1) and (2,2) inversion emission at a resolution of 30 arcsec in 8 arcmin regions towards the positions of embedded massive star formation. We have identified a total of 115 distinct clumps, approximately two-thirds of which are associated with an embedded massive young stellar object or compact HII region, while the others are classified as quiescent. There is a strong spatial correlation between the peak NH3 emission and the presence of embedded objects. We derive the spatial distribution of the kinetic gas temperatures, line widths, and NH3 column densities from these maps, and by combining these data with dust emission maps we estimate clump masses, H_2_ column densities and ammonia abundances. The clumps have typical masses of ~1000M_{sun}_ and radii ~0.5pc, line widths of ~2km/s and kinetic temperatures of ~16-20K. We find no significant difference between the sizes and masses of the star-forming and quiescent subsamples; however, the distribution maps reveal the presence of temperature and line width gradients peaking towards the centre for the star-forming clumps while the quiescent clumps show relatively uniform temperatures and line widths throughout. Virial analysis suggests that the vast majority of clumps are gravitationally bound and are likely to be in a state of global free fall in the absence of strong magnetic fields. The similarities between the properties of the two subsamples suggest that the quiescent clumps are also likely to form massive stars in the future, and therefore provide an excellent opportunity to study the initial conditions of massive pre-stellar and protostellar clumps.
1467. RMS survey. 6cm observations of YSOs
ID:
ivo://CDS.VizieR/J/A+A/501/539
Title:
RMS survey. 6cm observations of YSOs
Short Name:
J/A+A/501/539
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified ~2000 MYSO candidates located throughout the Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of these follow-up observations is to identify other objects with similar colours such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. To identify the populations of UCHII regions and PNe within the sample and examine their Galactic distribution. We have conducted high resolution radio continuum observations at 6cm towards 659 MYSO candidates in the northern hemisphere (10{deg}<l<250{deg}) using the Very Large Array (VLA). These observations have a spatial resolution of ~1-2" and typical image rms noise values of ~0.22mJy - sensitive enough to detect a HII region powered by B0.5 star at the far side of the Galaxy. In addition to these targeted observations we present archival data towards a further 315 RMS sources extracted from a previous VLA survey of the inner Galaxy.
1468. RMS survey: molecular observations
ID:
ivo://CDS.VizieR/J/MNRAS/437/1791
Title:
RMS survey: molecular observations
Short Name:
J/MNRAS/437/1791
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the well-selected sample of ~1750 embedded, young, massive stars identified by the Red MSX Source (RMS) survey to investigate the Galactic distribution of recent massive star formation. We present molecular line observations for ~800 sources without existing radial velocities. We describe the various methods used to assign distances extracted from the literature and solve the distance ambiguities towards approximately 200 sources located within the solar circle using archival Hi data. These distances are used to calculate bolometric luminosities and estimate the survey completeness (~2x10^4^L_{sun}_). In total, we calculate the distance and luminosity of ~1650 sources, one third of which are above the survey's completeness threshold. Examination of the sample's longitude, latitude, radial velocities and mid-infrared images has identified ~120 small groups of sources, many of which are associated with well-known star formation complexes, such as G305, G333, W31, W43, W49 and W51. We compare the positional distribution of the sample with the expected locations of the spiral arms, assuming a model of the Galaxy consisting of four gaseous arms. The distribution of young massive stars in the Milky Way is spatially correlated with the spiral arms, with strong peaks in the source position and luminosity distributions at the arms' Galactocentric radii. The overall source and luminosity surface densities are both well correlated with the surface density of the molecular gas, which suggests that the massive star formation rate per unit molecular mass is approximately constant across the Galaxy. A comparison of the distribution of molecular gas and the young massive stars to that in other nearby spiral galaxies shows similar radial dependences. We estimate the total luminosity of the embedded massive star population to be ~0.76x10^8^L_{sun}_, 30 per cent of which is associated with the 10 most active star-forming complexes. We measure the scaleheight as a function of the Galactocentric distance and find that it increases only modestly from ~20-30pc between 4 and 8kpc, but much more rapidly at larger distances.
1469. RM Synthesis of 33 sources around M31
ID:
ivo://CDS.VizieR/J/A+A/559/A27
Title:
RM Synthesis of 33 sources around M31
Short Name:
J/A+A/559/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
Low-frequency radio continuum observations are best suited to search for radio halos of inclined galaxies. Polarization measurements at low frequencies allow the detection of small Faraday rotation measures caused by regular magnetic fields in galaxies and in the foreground of the Milky Way. The detection of low-frequency polarized emission from a spiral galaxy such as M31 allows us to assess the degree of Faraday depolarization, which can be compared with models of the magnetized interstellar medium.
1470. ROGUE. I. SDSS galaxies with FIRST
ID:
ivo://CDS.VizieR/J/ApJS/247/53
Title:
ROGUE. I. SDSS galaxies with FIRST
Short Name:
J/ApJS/247/53
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the catalog of Radio sources associated with Optical Galaxies and having Unresolved or Extended morphologies I (ROGUE I), consisting of 32616 spectroscopically selected galaxies. It is the largest handmade catalog of this kind, obtained by cross-matching galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 7 and radio sources from both the First Images of Radio Sky at Twenty Centimetre (FIRST) survey and the NRAO Very Large Array Sky Survey, without imposing a limit on the radio flux densities. The catalog provides a visual classification of radio and optical morphologies of galaxies presenting a FIRST core within 3" of the optical position. The radio morphological classification is performed by examining the radio-optical overlays of linear sizes equal to 1Mpc at the source distance, while the 120" image snapshots from the SDSS database are used for optical classification. The results of our search are as follows: (i) single-component unresolved and elongated radio sources constitute the major group in the ROGUE I catalog (~90%), and ~8% exhibit extended morphologies; (ii) samples of 269, 730, and 115 Fanaroff-Riley (FR) type I, II, and hybrid galaxies, respectively, are presented; (iii) we report 55 newly discovered giant/possible giant, 16 double-double, 9 X-shaped, and 25 Z-shaped radio sources; (iv) on the optical front, most galaxies have elliptical morphologies (~62%) while spirals form the second major category (~17%) followed by distorted (~12%) and lenticular (~7%) morphologies; and (v) division between the FR I and the FR II sources in the radio-optical luminosity plane is blurred, in tune with recent studies.

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