- ID:
- ivo://CDS.VizieR/J/AZh/84/839
- Title:
- Methanol emission of isolated maser condensations
- Short Name:
- J/AZh/84/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of the radial velocities of class I methanol masers relative to the velocities of their parent molecular clouds is analyzed. This analysis is based on catalog data for methanol masers detected up to the present time in both the northern and southern hemispheres, together with catalog data for the CS(2-1) line, which traces dense, quiescent gas. Results for a large sample of sources show that, in contrast to class II methanol masers, which undergo Keplerian motions in protoplanetary disks, class I methanol masers retain their velocities in the local system of rest of the surrounding medium, and do not participate in the ejection of matter in bipolar out flows. They can be adequately described using a model in which matter ejected from active parts of the associated star-forming regions flows around isolated maser condensations. This compresses the maser clumps, enhancing the concentration of methanol and facilitating collisional pumping of the masers.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AZh/79/328
- Title:
- Methanol maser condensations in W 48
- Short Name:
- J/AZh/79/328
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The methanol-line spectra in two maser condensations at velocities ~41 and ~45km/s in the star-forming region W 48 have been studied.
- ID:
- ivo://CDS.VizieR/J/AZh/79/610
- Title:
- Methyl acetylene observations of warm clouds
- Short Name:
- J/AZh/79/610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a survey of 63 galactic star-forming region in the 6k-5k and 5k-4k methyl acetylene lines at 102.5 and 85.5GHz are presented. Fourty-three sources were detected at 102.5GHz, and twenty-five at 85.5GHz
- ID:
- ivo://CDS.VizieR/J/A+A/636/A16
- Title:
- M43, Horsehead, MonR2, M17SW [CII]158um spectra
- Short Name:
- J/A+A/636/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The [CII] 158um FIR fine-structure line is one of the most important cooling lines of the star-forming ISM. It is used as a tracer of star formation efficiency in external galaxies and to study feedback effects in parental clouds. High spectral resolution observations have shown complex structures in the line profiles of the [CII] emission. To determine whether the complex profiles observed in [^12^CII] are due to individual velocity components along the line-of-sight or due to self-absorption, one has to compare the [^12^CII] and isotopic [^13^CII] line profiles. Deep integrations with the SOFIA/upGREAT 7-pixel array receiver in the sources M43, Horsehead PDR, Monoceros R2 and M17 SW allow to detect with high S/N the optically thin [^13^CII] and simultaneously the [^12^CII] emission lines. We first derive the [^12^CII] optical depth and the [CII] column density from a single component model. However, the complex line profiles observed require a double layer model with an emitting background and an absorbing foreground. A multi-component velocity fit allows to derive the physical conditions of the [CII] gas: column density and excitation temperature. We find moderate to high [^12^CII] optical depths in all four sources, and self-absorption of [^12^CII] in Mon R2 and M17 SW. The high column density of the warm background emission corresponds to an equivalent Av of up to 41mag. The foreground absorption requires substantial column densities of cold and dense [CII] gas, with an equivalent Av ranging up to about 13mag. The column density of the warm background material requires multiple PDR surfaces stacked along the line of sight and in velocity. The substantial column density of dense and cold foreground [CII] gas detected in absorption cannot be explained with any known scenario and we can only speculate about its origin.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/1507
- Title:
- Mid-IR photometry in IC 1396A
- Short Name:
- J/ApJ/702/1507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used Spitzer/Infrared Array Camera (IRAC) to conduct a photometric monitoring program of the IC1396A dark globule in order to study the mid-IR (3.6-8um) variability of the heavily embedded young stellar objects (YSOs) present in that area. We obtained light curves covering a 14 day timespan with a twice daily cadence for 69 YSOs, and continuous light curves with approximately 12s cadence over 7hr for 38 YSOs. Typical accuracies for our relative photometry were 1%-2% for the long timespan data and a few millimagnitude, corresponding to less than 0.5%, for the 7hr continuous "staring-mode" data. More than half of the YSOs showed detectable variability, with amplitudes from ~0.05mag to ~0.2mag. One star, IC1396A-47, shows a 3.5hr periodic light curve; this object may be a PMS Delta Scuti star.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A135
- Title:
- Mid-J CO emission of Top100 clumps
- Short Name:
- J/A+A/622/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-mass stars are formed within massive molecular clumps, where a large number of stars form close together. The evolution of the clumps with different masses and luminosities is mainly regulated by their high-mass stellar content and the formation of such objects is still not well understood. In this work, we characterise the mid-J CO emission in a statistical sample of 99 clumps (TOP100) selected from the ATLASGAL survey that are representative of the Galactic proto-cluster population. High-spatial resolution APEX-CHAMP+ maps of the CO (6-5) and CO (7-6) transitions were obtained and combined with additional single-pointing APEX-FLASH+ spectra of the CO (4-3) line. The data were convolved to a common angular resolution of 13.4". We analysed the line profiles by fitting the spectra with up to three Gaussian components, classified as narrow or broad, and computed CO line luminosities for each transition. Additionally, we defined a distance-limited sample of 72 sources within 5kpc to check the robustness of our analysis against beam dilution effects. We have studied the correlations of the line luminosities and profiles for the three CO transitions with the clump properties and investigate if and how they change as a function of the evolution. All sources were detected above 3-{sigma} in all three CO transitions and most of the sources exhibit broad CO emission likely associated with molecular outflows. We find that the extension of the mid-J CO emission is correlated with the size of the dust emission traced by the Herschel-PACS 70um maps. The CO line luminosity (LCO) is correlated with the luminosity and mass of the clumps. However, it does not correlate with the luminosity-to-mass ratio. The dependency of the CO luminosity with the properties of the clumps is steeper for higher-J transitions. Our data seem to exclude that this trend is biased by self-absorption features in the CO emission, but rather suggest that different J transitions arise from different regions of the inner envelope. Moreover, high-mass clumps show similar trends in CO luminosity as lower mass clumps, but are systematically offset towards larger values, suggesting that higher column density and (or) temperature (of unresolved) CO emitters are found inside high-mass clumps.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A96
- Title:
- Mid-J CO shock tracing observations of IRDCs II
- Short Name:
- J/A+A/587/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present maps measuring 4 square arcminutes of the ^12^CO, ^13^CO, and C^18^O J=3 to 2 lines from selected locations within the C and F (G028.37+00.07 and G034.43+00.24) infrared dark clouds (IRDCs), as well as single pointing observations of the ^13^CO and C^18^O J=2 to 1 lines towards three cores within these clouds. We derive CO gas temperatures throughout the maps and find that CO is significantly frozen out within these IRDCs. We find that the CO depletion tends to be the highest near column density peaks with maximum depletion factors between 5 and 9 in IRDC F and between 16 and 31 in IRDC C. We also detect multiple velocity components and complex kinematic structure in both IRDCs. Therefore, the kinematics of IRDCs seem to point to dynamically evolving structures yielding dense cores with considerable depletion factors.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/57
- Title:
- Milky Way molecular clouds from ^12^CO
- Short Name:
- J/ApJ/834/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the ^12^CO emission observed within b+/-5^{deg}^. The catalog was produced using a hierarchical cluster identification method applied to the result of a Gaussian decomposition of the Dame+ (2001ApJ...547..792D) data. The total H_2_ mass in the catalog is 1.2x10^9^M_{sun}_, in agreement with previous estimates. We find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. The most probable cloud size is R~30pc. We find that M{propto}R^2.2+/-0.2^, with no correlation between the cloud surface density, {Sigma}, and R. In contrast with the general idea, we find a rather large range of values of {Sigma}, from 2 to 300M_{sun}_/pc^2^, and a systematic decrease with increasing Galactic radius, R_gal_. The cloud velocity dispersion and the normalization {sigma}_0_={sigma}_v_/R^1/2^ both decrease systematically with R_gal_. When studied over the whole Galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between {sigma}_v_ and {Sigma}R. The normalization of this correlation is constant to better than a factor of two for R_gal_<20kpc. This relation is used to disentangle the ambiguity between near and far kinematic distances. We report a strong variation of the turbulent energy injection rate. In the outer Galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/488/1141
- Title:
- Milky Way Project DR2 bubbles & bow shocks
- Short Name:
- J/MNRAS/488/1141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Citizen science has helped astronomers comb through large data sets to identify patterns and objects that are not easily found through automated processes. The Milky Way Project (MWP), a citizen science initiative on the Zooniverse platform, presents internet users with infrared (IR) images from Spitzer Space Telescope Galactic plane surveys. MWP volunteers make classification drawings on the images to identify targeted classes of astronomical objects. We present the MWP second data release (DR2) and an updated data reduction pipeline written in Python. We aggregate 3 million classifications made by MWP volunteers during the years 2012-2017 to produce the DR2 catalogue, which contains 2600 IR bubbles and 599 candidate bow-shock driving stars. The reliability of bubble identifications, as assessed by comparison to visual identifications by trained experts and scoring by a machine-learning algorithm, is found to be a significant improvement over DR1. We assess the reliability of IR bow shocks via comparison to expert identifications and the colours of candidate bow-shock driving stars in the 2MASS point-source catalogue. We hence identify highly-reliable subsets of 1394 DR2 bubbles and 453 bow-shock driving stars. Uncertainties on object coordinates and bubble size/shape parameters are included in the DR2 catalog. Compared with DR1, the DR2 bubbles catalogue provides more accurate shapes and sizes. The DR2 catalogue identifies 311 new bow shock driving star candidates, including three associated with the giant HII regions NGC 3603 and RCW 49.
- ID:
- ivo://CDS.VizieR/J/A+A/476/1243
- Title:
- Millimeter continuum mapping of Cygnus X
- Short Name:
- J/A+A/476/1243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a millimeter continuum survey of the entire Cygnus X molecular complex. We used the MAMBO and MAMBO-2 bolometer arrays on the IRAM 30m telescope to map a 3deg^2^ area at 1.2mm (see fits files of Figures 2, kept to 11" resolution). Our MAMBO-2 imaging gives a complete view of the cloud structures ranging from 0.03pc to 5pc, i.e. from dense cores to clumps. We perform a multi-resolution analysis to extract 129 compact dense cores (~0.1pc, see Table 1) and identify 40 massive large-scale clumps (~0.7pc, see Table 2). The 21um fluxes arising from dense cores are taken from the MSX point source catalog (MSX C6, Cat. <V/114>).
