- ID:
- ivo://CDS.VizieR/J/A+A/647/A110
- Title:
- Arches cluster JVLA 6 and 10GHz images
- Short Name:
- J/A+A/647/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high angular resolution radio observations of the Arches cluster in the Galactic centre, one of the most massive young clusters in the Milky Way. The data were acquired in two epochs and at 6 and 10 GHz with the Karl G. Jansky Very Large Array (JVLA). The rms noise reached is 3-4 times better than previous observations and we have almost doubled the number of known radio stars in the cluster. Nine of them have spectral indices consistent with thermal emission from ionised stellar winds. One is a confirmed wind colliding binary and two sources are ambiguous cases. Regarding variability, the radio emission appears to be stable on time scales of a few to ten years. Finally, we have showed that the number of radio stars can be used as a tool for constraining the age or mass of a cluster and also its mass function.
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- ID:
- ivo://CDS.VizieR/J/ApJ/880/141
- Title:
- Arecibo 21cm obs. of sources in 5 GMC regions
- Short Name:
- J/ApJ/880/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report Arecibo 21cm absorption-emission observations to characterize the physical properties of neutral hydrogen (HI) in the proximity of five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong HI absorption was detected toward all 79 background-continuum sources in the ~60x20 square degree region. Gaussian decompositions were performed to estimate temperatures, optical depths, and column densities of the cold and warm neutral medium (CNM and WNM). The properties of individual CNM components are similar to those previously observed along random Galactic sightlines and in the vicinity of molecular clouds, suggesting a universality of cold HI properties. The CNM spin temperature (Ts) histogram peaks at ~50K. The turbulent Mach numbers of CNM components vary widely, with a typical value of ~4, indicating that their motions are supersonic. About 60% of the total HI gas is WNM, and nearly 40% of the WNM lies in thermally unstable regime 500-5000K. The observed CNM fraction is higher around GMCs than in diffuse regions, and increases with increasing column density (N_HI_) to a maximum of ~75%. On average, the optically thin approximation (N_HI_^*^) underestimates the total column density by ~21%, but we find large regional differences in the relationship between N_HI_ and the required correction factor, f=N_HI_/N_HI_^*^. We examine two different methods (linear fit of f versus log_10_(N_HI_^*^) and uniform Ts) to correct for opacity effects using emission data from the GALFA-HI survey. We prefer the uniform Ts method because the linear relationship does not produce convincing fits for all subregions.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/255
- Title:
- Arecibo methanol maser Galactic Plane Survey
- Short Name:
- J/ApJ/656/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an unbiased survey for 6.7GHz methanol masers in the Galactic plane carried out using the 305m Arecibo radio telescope. A total of 18.2deg^2^ was surveyed with uniform sampling at 35.2<=l<=53.7, |b|<=0.41. The large collecting area of Aecibo and the sensitive C-Band High receiver allowed the survey to be complete at the level of 0.27Jy, making this the most sensitive blind survey carried out to date. We detected a total of 86 sources, 48 of which are new detections. Most of the new detections have a peak flux density below 2Jy. Many methanol masers are clustered, reflecting the formation of massive stars in clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/669/435
- Title:
- Arecibo Methanol Maser Galactic Plane Survey. II.
- Short Name:
- J/ApJ/669/435
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the properties of the 6.7GHz methanol maser sample detected in the Arecibo Methanol Maser Galactic Plane Survey. The distribution of the masers in the Galaxy, and statistics of their multiwavelength counterparts is consistent with the hypothesis of 6.7GHz maser emission being associated with massive young stellar objects. Using the detection statistics of our survey, we estimate the minimum number of methanol masers in the Galaxy to be 1275.
- ID:
- ivo://CDS.VizieR/J/ApJS/93/549
- Title:
- Arecibo 1612 MHz survey supplement
- Short Name:
- J/ApJS/93/549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The completeness of the Arecibo 1612 MHz survey of color-selected/IRAS sources (see references) is extended to (25-12){mu}m>-0.7. In addition (1) most IR sources with spectral types normally associated with OH/IR stars and colors outside the coverage of the original survey have been examined; (2) most ambiguous observations during the survey have been reobserved: (3) most single peaked sources have been reexamined, and 17 found with second peaks. We report 39 new 1612MHz detections, of which 34 are original. These are also surveyed in the mainlines. Analysis of the complete flux-limited survey confirms the existence of a longitude sensitivity effect in the detection of sources, which reduces the total number detected by ~4%. This analysis sets an upper limit of 16%, on the proportion of a color-selected sample that may be identified with carbon stars and/or star-formation regions.
- ID:
- ivo://CDS.VizieR/VIII/9
- Title:
- Argentina High-Latitude H I Survey
- Short Name:
- VIII/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This survey consists of H I 21-cm spectra covering the southern sky with absolute galactic latitude |b|>10 degrees and a declination dec<-25 degrees. The observations were made with the 30m telescope of the Instituto Argentino de Radioastronomia during 1973 to 1977 and were described in Colomb et al. (1977A&AS...29...89C). The data were obtained by keeping the telescope fixed on the meridian at the desired declination and letting the sky drift through the field. The individual spectra were obtained with a 56-channel filterbank and covering the velocity range from about -40 to +40km/s. The velocity resolution is 2km/s, and the beamwidth is 30arcmin.
- ID:
- ivo://CDS.VizieR/J/MNRAS/490/1202
- Title:
- ASKAP EMU ESP, Radio Continuum Survey of the SMC
- Short Name:
- J/MNRAS/490/1202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two new radio continuum images from the Australian Square Kilometre Array Pathnder (ASKAP) survey in the direction of the Small Magellanic Cloud (SMC). These images are part of the Evolutionary Map of the Universe (EMU) Early Science Project (ESP) survey of the Small and Large Magellanic Clouds. The two new source lists produced from these images contain radio continuum sources observed at 960MHz (4489 sources) and 1320MHz (5954 sources) with a bandwidth of 192MHz and beam sizes of 30.0"x30.0" and 16.3"x15.1", respectively. The median Root Mean Squared (RMS) noise values are 186Jy/beam (960MHz) and 165Jy/beam (1320MHz). To create point source catalogues, we use these two source lists, together with the previously published Molonglo Observatory Synthesis Telescope (MOST) and the Australia Telescope Compact Array (ATCA) point source catalogues to estimate spectral indices for the whole population of radio point sources found in the survey region. Combining our ASKAP catalogues with these radio continuum surveys, we found 7736 point-like sources in common over an area of 30deg^2^. In addition, we report the detection of two new, low surface brightness supernova remnant candidates in the SMC. The high sensitivity of the new ASKAP ESP survey also enabled us to detect the bright end of the SMC planetary nebula sample, with 22 out of 102 optically known planetary nebulae showing point-like radio continuum emission. Lastly, we present several morphologically interesting background radio galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/83
- Title:
- Associations to 1FGL sources
- Short Name:
- J/ApJ/753/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of {gamma}-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit {gamma} rays, 630 of these sources are "unassociated" (i.e., have no obvious counterparts at other wavelengths). Here, we employ two statistical analyses of the primary {gamma}-ray characteristics for these unassociated sources in an effort to correlate their {gamma}-ray properties with the active galactic nucleus (AGN) and pulsar populations in 1FGL. Based on the correlation results, we classify 221 AGN-like and 134 pulsar-like sources in the 1FGL unassociated sources. The results of these source "classifications" appear to match the expected source distributions, especially at high Galactic latitudes. While useful for planning future multiwavelength follow-up observations, these analyses use limited inputs, and their predictions should not be considered equivalent to "probable source classes" for these sources. We discuss multiwavelength results and catalog cross-correlations to date, and provide new source associations for 229 Fermi-LAT sources that had no association listed in the 1FGL catalog. By validating the source classifications against these new associations, we find that the new association matches the predicted source class in ~80% of the sources.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A80
- Title:
- Astrometric classification of 647 VLBI sources
- Short Name:
- J/A+A/618/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the result of our Allan standard deviation based classification according to their astrometric stability. The classification is divided into three categories (stable sources, intermediate sources, unstable sources). Stability of sources is qualified by the astrometric behavior of the source. This determines in which category the source falls into. Then, stability of the source is also quantified by a stability index (two are proposed in the table). Those indexes enable to order sources in each category of the classification.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A10
- Title:
- Astrometric positions of radio sources
- Short Name:
- J/A+A/510/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the results of an investigation of astrometric positions of extragalactic radio sources from a list for the International Celestial Reference Frame.
