- ID:
- ivo://CDS.VizieR/J/A+A/619/A35
- Title:
- 86GHz SiO maser survey of late-type stars. IV
- Short Name:
- J/A+A/619/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an 86GHz SiO (v=1, J=2->1) maser search towards late-type stars located within |b|<0.5{deg} and 20{deg}<l<50{deg}. This search is an extension at longer longitudes of the work by Messineo et al. (2002, Cat. J/A+A/393/115). We selected 135 stars from the MSX catalog using color and flux criteria and detected 92 (86 new detections). The detection rate is 68%, the same as in our previous study. The last few decades have seen the publication of several catalogues of point sources detected in infrared surveys (MSX, 2MASS, DENIS, ISOGAL, WISE, GLIMPSE, AKARI, and MIPSGAL). We searched each catalogue for data on the 444 targets of our earlier survey and for the 135 in the survey reported here. We confirm that, as anticipated, most of our targets have colors typical of oxygen-rich AGB stars. Only one target star may have left the AGB already. Ten stars have colors typical of carbon-rich stars, meaning a contamination of our sample with carbon stars of <=1.7%.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/716/521
- Title:
- 31GHz sky survey with the SZA
- Short Name:
- J/ApJ/716/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first sample of 31GHz selected sources to flux levels of 1mJy. From late 2005 to mid-2007, the Sunyaev-Zel'dovich Array observed 7.7deg^2^ of the sky at 31GHz to a median rms of 0.18mJy/beam. We identify 209 sources at greater than 5{sigma} significance in the 31GHz maps, ranging in flux from 0.7mJy to ~200mJy. Archival NVSS data at 1.4GHz and observations at 5GHz with the Very Large Array are used to characterize the sources. We determine the maximum-likelihood integrated source count to be N(>S)=(27.2+/-2.5)deg^-2^x(S_mJy_)^-1.18+/-0.12^ over the flux range 0.7-15mJy. This result is significantly higher than predictions based on 1.4GHz selected samples, a discrepancy which can be explained by a small shift in the spectral index distribution for faint 1.4GHz sources. From comparison with previous measurements of sources within the central arcminute of massive clusters, we derive an overdensity of 6.8+/-4.4, relative to field sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/845/44
- Title:
- 340GHz SMA obs. of 50 nearby protoplanetary disks
- Short Name:
- J/ApJ/845/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey at subarcsecond resolution of the 340GHz dust continuum emission from 50 nearby protoplanetary disks, based on new and archival observations with the Submillimeter Array. The observed visibility data were modeled with a simple prescription for the radial surface brightness profile. The results were used to extract intuitive, empirical estimates of the emission "size" for each disk, R_eff_, defined as the radius that encircles a fixed fraction of the total continuum luminosity, L_mm_. We find a significant correlation between the sizes and luminosities, such that R_eff_{propto}L_mm_^0.5^, providing a confirmation and quantitative characterization of a putative trend that was noted previously. This correlation suggests that these disks have roughly the same average surface brightness interior to their given effective radius, ~0.2Jy/arcsec^2^ (or 8K in brightness temperature). The same trend remains, but the 0.2dex of dispersion perpendicular to this relation essentially disappears, when we account for the irradiation environment of each disk with a crude approximation of the dust temperatures based on the stellar host luminosities. We consider two (not mutually exclusive) explanations for the origin of this size-luminosity relationship. Simple models of the growth and migration of disk solids can account for the observed trend for a reasonable range of initial conditions, but only on timescales that are much shorter than the nominal ages present in the sample. An alternative scenario invokes optically thick emission concentrated on unresolved scales, with filling factors of a few tens of percent, which is perhaps a manifestation of localized particle traps.
5474. 1.4 GHz source survey
- ID:
- ivo://CDS.VizieR/J/AJ/99/1071
- Title:
- 1.4 GHz source survey
- Short Name:
- J/AJ/99/1071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on 1.4GHz continuum observations for 56 contiguous VLA fields, using the D configuration, in a region devoid of nearby, rich galaxy clusters (at z<0.4). 354 continuum sources are tabulated, with fluxes down to about 1.5mJy, in an area of about 12degres^+2^. Only about seven of the 354 radio sources are associated with known rich galaxy clusters at z>0.4 (tabulated by Gunn, Hoessel, and Oke, 1986ApJ...306...30G). We compare source positions with those from an optical catalog (generated from a POSS plate with the use of the Minnesota Automated Plate Scanner) and find mild correlations on angular scales of order 1arcmin. This suggests some association of radio sources with galaxy groups (sizes of order 200 kpc) at redshifts of order z~0.1, even though there are no rich galaxy clusters in this redshift range.
5475. 1-22 GHz spectra survey
- ID:
- ivo://CDS.VizieR/J/A+AS/139/545
- Title:
- 1-22 GHz spectra survey
- Short Name:
- J/A+AS/139/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observational results for extragalactic radio sources with milliarcsecond components, obtained with the 600 meter ring radio telescope RATAN-600 from 1st to 22nd December, 1997. For each source, a six frequency broad band radio spectrum was obtained by observing simultaneously with an accuracy up to a minute at 1.4, 2.7, 3.9, 7.7, 13 and 31 cm. The observed list is selected from Preston et al. (1985AJ.....90.1599P) VLBI survey and contains all the sources in the declinations between -30 and +43 degrees with a correlated flux density exceeding 0.1 Jy at 13 cm. The sample includes the majority of sources to be studied in the current VSOP survey and the future RadioAstron Space VLBI mission.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A147
- Title:
- 80-116GHz spectrum of L483
- Short Name:
- J/A+A/625/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An exhaustive chemical characterization of dense cores is mandatory to our understanding of chemical composition changes from a starless to a protostellar stage. However, only a few sources have had their molecular composition characterized in detail. Here we present a 3mm line survey of L483, a dense core around a Class 0 protostar, which was observed with the IRAM 30m telescope in the 80-116GHz frequency range. We detected 71 molecules (140 including different isotopologs), most of which are present in the cold and quiescent ambient cloud according to their narrow lines (FWHM~0.5km/s) and low rotational temperatures (<~10K). Of particular interest among the detected molecules are the cis isomer of HCOOH, the complex organic molecules HCOOCH_3_, CH_3_OCH_3_, and C_2_H_5_OH, a wide variety of carbon chains, nitrogen oxides like N_2_O, and saturated molecules like CH_3_SH, in addition to eight new interstellar molecules (HCCO, HCS, HSC, NCCNH^+^, CNCN, NCO, H_2_NCO^+^, and NS^+^) whose detection has already been reported. In general, fractional molecular abundances in L483 are systematically lower than in TMC-1 (especially for carbon chains), tend to be higher than in L1544 and B1-b, and are similar to those in L1527. Apart from the overabundance of carbon chains in TMC-1, we find that L483 does not have a marked chemical differentiation with respect to starless/prestellar cores like TMC-1 and L1544, although it does chemically differentiate from Class 0 hot corino sources like IRAS 16293-2422. This fact suggests that the chemical composition of the ambient cloud of some Class 0 sources could be largely inherited from the dark cloud starless/prestellar phase. We explore the use of potential chemical evolutionary indicators, such as the HNCO/C_3_S, SO_2_/C_2_S, and CH_3_SH/C_2_S ratios, to trace the prestellar/protostellar transition. We also derived isotopic ratios for a variety of molecules, many of which show isotopic ratios close to the values for the local interstellar medium (remarkably all those involving ^34^S and ^33^S), while there are also several isotopic anomalies like an extreme depletion in ^13^C for one of the two isotopologs of c-C_3_H_2_, a drastic enrichment in ^18^O for SO and HNCO (SO being also largely enriched in ^17^O), and different abundances for the two ^13^C substituted species of C_2_H and the two ^15^N substituted species of N_2_H^+^. We report the first detection in space of some minor isotopologs and quantify for the first time the deuterium fractionation for HDCCO and c-C_3_D. The exhaustive chemical characterization of L483 presented here, together with similar studies of other prestellar and protostellar sources, should allow us to identify the main factors that regulate the chemical composition of cores along the process of formation of low-mass protostars.
- ID:
- ivo://CDS.VizieR/J/ApJ/533/611
- Title:
- 1.4GHz survey in HDF region
- Short Name:
- J/ApJ/533/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a deep radio survey with the Very Large Array at 1.4GHz of a region containing the Hubble Deep Field (HDF). This survey overlaps previous observations at 8.5GHz allowing us to investigate the radio spectral properties of microJansky sources to flux densities greater than 40{mu}Jy at 1.4GHz and greater than 8{mu}Jy at 8.5GHz. A total of 371 sources have been catalogued at 1.4GHz as part of a complete sample within 20 of the HDF.
- ID:
- ivo://CDS.VizieR/J/A+AS/41/421
- Title:
- 1.4GHz survey in the Virgo region
- Short Name:
- J/A+AS/41/421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum observations made with the Westerbork Synthesis Radio Telescope at 1.4GHz are presented for 274 galaxies in the Virgo Cluster region. The observations are partly full syntheses and partly east-west strip distributions. For the 55 detected galaxies the emission is separated into central and extended components. A brief summary of the analysis is also given.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/1433
- Title:
- 31GHz survey of low-frequency radio sources
- Short Name:
- J/ApJ/704/1433
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 100m Robert C. Byrd Green Bank Telescope and the 40m Owens Valley Radio Observatory telescope have been used to conduct a 31GHz survey of 3165 known extragalactic radio sources over 143deg^2^ of the sky. Target sources were selected from the NRAO VLA Sky Survey in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4GHz flux densities of 3-10mJy. The resulting 31GHz catalogs are presented in full online. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4-31GHz spectral indices of these sources, we find a mean 31-1.4GHz flux ratio of 0.110+/-0.003 corresponding to a spectral index of {alpha}=-0.71+/-0.01 (S_{nu}_{prop.to}{nu}^{alpha}^); 9.0%+/-0.8% of sources have {alpha}>-0.5 and 1.2%+/-0.2% have {alpha}>0. By combining this spectral-index distribution with 1.4GHz source counts, we predict 31GHz source counts in the range 1mJy<S_31_<4mJy, N(>S_31_)=(16.7+/-1.7)deg^-2^(S_31_/1mJy)^-0.80+/-0.07^.
- ID:
- ivo://CDS.VizieR/J/ApJ/874/64
- Title:
- 5GHz TMRT observations of 71 pulsars
- Short Name:
- J/ApJ/874/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present integrated pulse profiles at 5GHz for 71 pulsars, including eight millisecond pulsars (MSPs), obtained using the Shanghai Tian Ma Radio Telescope. Mean flux densities and pulse widths are measured. For 19 normal pulsars and one MSP, these are the first detections at 5GHz --and for a further 19, including five MPSs, the profiles have a better signal-to-noise ratio than previous observations. Mean flux density spectra between 400MHz and 9GHz are presented for 27 pulsars and correlations of power-law spectral index are found with characteristic age, radio pseudo-luminosity, and spin-down luminosity. Mode changing was detected in five pulsars. The separation between the main pulse and interpulse is shown to be frequency independent for six pulsars, but a frequency dependence of the relative intensity of the main pulse and interpulse is found. The frequency dependence of component separations is investigated for 20 pulsars, and three groups are found: in seven cases, the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping; in 11 cases, the separation is nearly constant; in the remaining two cases, the separation between the outmost components increases with frequency. We obtain the correlations of pulse widths with pulsar period and estimate the core widths of 23 multicomponent profiles and conal widths of 17 multicomponent profiles at 5GHz using Gaussian fitting, and we discuss the width-period relationship at 5GHz compared with the results at at 1.0 and 8.6GHz.