- ID:
- ivo://CDS.VizieR/J/A+A/642/L7
- Title:
- IRAS 04302+2247 CO, CS, CN, H2CO, CH3OH maps
- Short Name:
- J/A+A/642/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical composition of planets is inherited from that of the natal protoplanetary disk at the time of planet formation. Increasing observational evidence suggests that planet formation occurs in less than 1-2Myr. This motivates the need for spatially resolved spectral observations of young Class I disks, as carried out by the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT). In the context of ALMA-DOT, we observe the edge-on disk around the Class I source IRAS 04302+2247 (the butterfly star) in the 1.3mm continuum and five molecular lines. We report the first tentative detection of methanol (CH_3_OH) in a Class I disk and resolve, for the first time, the vertical structure of a disk with multiple molecular tracers. The bulk of the emission in the CO 2-1, CS 5-4, and o-H_2_CO 3_1,2_-2_1,1_ lines originates from the warm molecular layer, with the line intensity peaking at increasing disk heights, z, for increasing radial distances, r. Molecular emission is vertically stratified, with CO observed at larger disk heights (aperture z/r~0.41-0.45) compared to both CS and H2CO, which are nearly cospatial (z/r~0.21-0.28). In the outer midplane, the line emission decreases due to molecular freeze-out onto dust grains (freeze-out layer) by a factor of >100 (CO) and 15 (CS). The H_2_CO emission decreases by a factor of only about 2, which is possibly due to H2CO formation on icy grains, followed by a nonthermal release into the gas phase. The inferred [CH_3_OH]/[H_2_CO] abundance ratio is 0.5-0.6, which is 1-2 orders of magnitude lower than for Class 0 hot corinos, and a factor ~2.5 lower than the only other value inferred for a protoplanetary disk (in TW Hya, 1.3-1.7). Additionally, it is at the lower edge but still consistent with the values in comets. This may indicate that some chemical reprocessing occurs in disks before the formation of planets and comets.
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Search Results
- ID:
- ivo://CDS.VizieR/II/156A
- Title:
- IRAS Faint Source Catalog, |b| > 10, Version 2.0
- Short Name:
- II/156A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Faint Source Survey (FSS) is the definitive Infrared Astronomical Satellite data set for faint point sources. The FSS was produced by point-source filtering the individual detector data streams and then coadding those data streams using a trimmed-average algorithm. The resulting images, or plates, give the best estimate from the IRAS survey data of the point source flux density at every surveyed point of the sky. The Faint Source Catalog (FSC) is a compilation of the sources extracted from the FSS plates that have met reasonable reliability requirements. Averaged over the whole catalog, the FSC is at least 98.5% reliable at 12 and 25 microns, and ~94% at 60 microns. For comparison, the IRAS Point Source Catalog (PSC) is >99.997% reliable, but the sensitivity of the FSC exceeds that of the PSC by about a factor of 2.5. The FSC contains data for 173,044 point sources in unconfused regions with flux densities typically above 0.2 Jy at 12, 25, and 60 microns, and above 1.0 Jy at 100 microns. The FSS plates are somewhat more sensitive but less reliable than the FSC; typically, only sources with SNR>5-6 in the plates are contained in the FSC. Sources with SNR>3 but which do not meet the reliability requirements of the FSC are catalogued in the Faint Source Reject File (FSR, Cat. II/275). The data products, the processing methods used to produce them, results of an analysis of these products, and cautionary notes are given in the Explanatory Supplement to the IRAS Faint Source Survey (see references in fsc.txt).
- ID:
- ivo://CDS.VizieR/II/275
- Title:
- IRAS Faint Source Reject Catalog
- Short Name:
- II/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Faint Source Reject Catalog contains 593,516 sources rejected for inclusion in the Faint Source Catalog (Cat. II/156) because they failed to meet one or more of the criteria established to ensure the reliability of the FSC. The REJECTED sources in the FSR are either in confused regions of the sky, or in areas with |b|<10-20{deg}, or were detected only in a single band with a signal-to-noise ratio of 3-6. The FSR also includes sources from areas of the sky covered by fewer than six detector passes, and sources contaminated by or caused by cometary debris trails. The files described here contain selected columns from the original Faint Source Reject IRAS catalogue; the full set is available as a ascii FITS table. In the descriptions below, the original names of the columns are added at the end of the explanations of each column.
- ID:
- ivo://CDS.VizieR/J/A+A/451/431
- Title:
- IRAS fluxes in LMC starburst regions
- Short Name:
- J/A+A/451/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Filamentary structures of early type stars are found to be a common feature of the Magellanic Clouds formed at an age of about 0.9-2x10^8^yr. As we go to younger ages these large structures appear fragmented and sooner or later form young clusters and associations. In the optical domain we have detected 56 such large structures of young objects, known as stellar complexes in the LMC for which we give coordinates and dimensions. We also investigate star formation activity and evolution of these stellar complexes and define the term "starburst region".
- ID:
- ivo://CDS.VizieR/J/AJ/105/427
- Title:
- IRAS fluxes of UCM galaxies
- Short Name:
- J/AJ/105/427
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of IRAS observations of the UCM (Universidad Complutense de Madrid) sample of emission-line galaxies, which have been selected from wide-dispersion H{alpha} objective-prism plates. These data are intended to provide a convenient summary of the relevant far-infrared (FIR) properties of these galaxies. Color-color diagrams, as interpreted by theoretical models, suggest that emission from UCM galaxies is mainly due to dust heated directly by photons emitted in active star-forming regions. Statistical analysis of some samples, including the IRAS minisurvey and blue selected objective-prism samples, have been performed. Comparisons, based on FIR luminosity distributions, with the IRAS minisurvey make evident the lower metallicity of the UCM galaxies which cannot be considered as a parent population of IRAS-detected galaxies. The FIR luminosity distributions of different samples have been compared using nonparametric methods and the best correlation has been found for the UCM and Wasilewski samples. Finally, a more detailed analysis of a UCM subsample has been performed from a three component model in order to get information concerning the fractional contribution of disk, star formation activity, and nonthermal mechanisms operating in the UCM galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/276/57
- Title:
- IRAS Galactic star-forming regions. II.
- Short Name:
- J/MNRAS/276/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the analysis of the occurrence of 22.2-GHz H_2_O maser emission in a sample of 1409 IRAS sources north of declination -30deg associated with star-forming regions are presented. Our sample contains all the IRAS sources that satisfy Emerson criteria for selecting molecular cores associated with the earliest evolutionary stages of the star-forming process. In a previous paper (Paper I, 1994MNRAS.266..123P), we have reported the results of the observations of about one third of the sample. In the present paper the observations of the remaining IRAS sources are presented: 18 of them are newly detected maser sources. The results show that 20 per cent of all IRAS sources that satisfy the Wood & Churchwell criteria have H2O water masers. This is in agreement with the assumption that these criteria select objects that are connected with the early phases of the evolution of high-mass star-forming regions. Moreover, about one third of the whole sample selected according to Emerson criteria contains IRAS sources that are not associated with massive star-forming processes, but probably with molecular cores in low-mass star-forming regions.
- ID:
- ivo://CDS.VizieR/J/ApJS/89/57
- Title:
- IRAS galaxies behind southern Milky Way
- Short Name:
- J/ApJS/89/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We systematically searched for IRAS galaxies with 60nm flux density larger than 0.6Jy by using the UK Schmidt Infrared and IIIa-J Atlases in the Milky Way region (|b|<15{deg}) between l=210{deg} and 360{deg}. We first selected about 4000 IRAS point sources by using our far-infrared criteria, which are optimized for the search of IRAS galaxies behind the Milky Way region, and then inspected visually the optical counterparts of them on the Schmidt Atlas film copies. We found 966 IRAS sources associated with galaxy-like objects. The list of the objects is presented here with the IRAS source name, Galactic coordinates, IRAS flux densities, field number and emulsion of the Atlas, type and size of galaxy(-like) image, redshift, multiplicity, and cross-identification. Of these, 423 galaxies are already catalogued in the Catalog of Galaxies and Quasars Observed in the IRAS Survey (Cat. <VII/113>), and most of the remaining 543 galaxy candidates are newly identified in this search. Although the radial velocities are known for only 387 galaxies, of which 60 were newly measured by us so far, we inferred the contamination by Galactic objects to be small from the good correlation between the sky distributions of the newly identified galaxy candidates and the previously catalogued galaxies. In the regions where the Galactic molecular clouds dominate, almost all the sources were not identified as galaxies. The detected galaxies are clustered in the three regions around l=240{deg}, 280{deg}, and 315{deg}, where the projected number densities are higher than the whole-sky average of IRAS galaxies of the same flux limit.
- ID:
- ivo://CDS.VizieR/J/A+A/299/347
- Title:
- IRAS galaxies behind Taurus clouds
- Short Name:
- J/A+A/299/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a complete search for IRAS galaxies in the Taurus molecular cloud region at l=169deg to 177deg and b=-19deg to -12deg. We selected a total number of 36 galaxies and galaxy candidates and looked for the 21-cm H I line in 25 objects; we detected H I emission in five of them including one with previously unknown redshift. The spatial density of IRAS galaxies with cz=4000 to 6000km/s is lower in this region than in the adjacent regions at both sides along galactic longitude, where the Perseus supercluster and the Gemini-Monoceros filament are respectively located.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/529
- Title:
- IRAS galaxies behind the Milky Way
- Short Name:
- J/A+AS/104/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We made a search for IRAS galaxies behind the Northern Milky Way by infrared selection using IRAS Point Source Catalog and visual inspection on POSS (Palomar Observatory Sky Survey) paper prints, and carried out a redshift survey of the identified objects. This paper presents a catalog of 649 IRAS galaxies with f_60_>=0.6Jy between l=150deg and 240deg at |b|<=15deg, which contains 254 newly identified galaxies and 188 newly measured radial velocities. Due to galactic extinction, our sample is a lower limit sample of the flux limited sample of IRAS galaxies, but it can give some information on the distribution of galaxies in the region perpendicular to the Supergalactic Plane. We confirm two regions with enhanced density at l~160deg, cz~5000km/s and l~190deg, cz~5000km/s and at least two possible voids.
- ID:
- ivo://CDS.VizieR/J/ApJS/95/457
- Title:
- IRAS images of nearby dark clouds
- Short Name:
- J/ApJS/95/457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated ~100 nearby molecular clouds using the extensive, all-sky database of IRAS. The clouds in this study cover a wide range of physical properties including visual extinction, size, mass, degree of isolation, homogeneity and morphology. IRAS 100 and 60 micrometre co-added images were used to calculate the 100 micrometre optical depth of dust in the clouds. These images of dust optical depth compare very well with ^12^CO and ^13^CO observations, and can be related to H_2_ column density. From the optical depth images we locate the edges of dark clouds and the dense cores inside them. We have identified a total of 43 "IRAS clouds" (regions with Av>2) which contain a total of 255 "IRAS cores" (regions with Av>4) and we catalog their physical properties. We find that the clouds are remarkably filamentary, and that the cores within the clouds are often distributed along the filaments. The largest cores are usually connected to other large cores by filaments. We have developed selection criteria to search the IRAS Point Source Catalog for stars that are likely to be associated with the clouds and we catalog the IRAS sources in each cloud or core. Optically visible stars associated with the clouds have been identified from the Herbig and Bell catalog. From these data we characterize the physical properties of the clouds including their star-formation efficiency.
