- ID:
- ivo://CDS.VizieR/J/A+A/630/A69
- Title:
- Radio observations of G074.11+00.11
- Short Name:
- J/A+A/630/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present molecular line and dust continuum observations of a Planck-detected cold cloud, G074.11+00.11. The cloud consists of a system of curved filaments and a central star-forming clump. The clump is associated with several infrared sources and H_2_O maser emission. We aim to determine the mass distribution and gas dynamics within the clump, to investigate if the filamentary structure seen around the clump repeats itself on a smaller scale, and to estimate the fractions of mass contained in dense cores and filaments. The velocity distribution of pristine dense gas can be used to investigate the global dynamical state of the clump, the role of filamentary inflows, filament fragmentation and core accretion. We use molecular line and continuum observations from single dish observatories and interferometry facilities to study the kinematics of the region. The molecular line observations show that the central clump may have formed as a result of a large-scale filament collision. The central clump contains three compact cores. Assuming a distance of 2.3kpc, based on Gaia observations and a three-dimensional extinction method of background stars, the mass of the central clump exceeds 700 solar masses, which is roughly 25% of the total mass of the cloud. Our virial analysis suggests that the central clump and all identified substructures are collapsing. We find no evidence for small-scale filaments associated with the cores. Our observations indicate that the clump is fragmented into three cores with masses in the range of [10,50] solar masses and that all three are collapsing. The presence of an H_2_O maser emission suggests active star formation. However the CO lines show only weak signs of outflows. We suggest that the region is young and any processes leading to star formation have just recently begun.
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- ID:
- ivo://CDS.VizieR/J/A+A/602/A61
- Title:
- Radio spectra of globulettes in Carina nebula
- Short Name:
- J/A+A/602/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carina nebula hosts a large number of globulettes. An optical study of these tiny molecular clouds shows that the majority are of planetary mass, but there are also those with masses of several tens up to a few hundred Jupiter masses. We seek to search for, and hopefully detect, molecular line emission from some of the more massive objects; in case of successful detection we aim to map their motion in the Carina nebula complex and derive certain physical properties. Methods.We carried out radio observations of molecular line emission in ^12^CO and ^13^CO (2-1) and (3-2) of 12 globulettes in addition to positions in adjacent shell structures using APEX. All selected objects were detected with radial velocities shifted relative to the emission from related shell structures and background molecular clouds. Globulettes along the western part of an extended dust shell show a small spread in velocity with small velocity shifts relative to the shell. This system of globulettes and shell structures in the foreground of the bright nebulosity surrounding the cluster Trumpler 14 is expanding with a few km/s relative to the cluster. A couple of isolated globulettes in the area move at similar speed. Compared to similar studies of the molecular line emission from globulettes in the Rosette nebula, we find that the integrated line intensity ratios and line widths are very different. The results show that the Carina objects have a different density/temperature structure than those in the Rosette nebula. In comparison the apparent size of the Carina globulettes is smaller, owing to the larger distance, and the corresponding beam filling factors are small. For this reason we were unable to carry out a more detailed modelling of the structure of the Carina objects in the way as performed for the Rosette objects. The Carina globulettes observed are compact and denser than objects of similar mass in the Rosette nebula. The distribution and velocities of these globulettes suggest that they have originated from eroding shells and elephant trunks. Some globulettes in the Trumpler 14 region are quite isolated and located far from any shell structures. These objects move at a similar speed as the globulettes along the shell, suggesting that they once formed from cloud fragments related to the same foreground shell.
- ID:
- ivo://CDS.VizieR/J/ApJ/807/5
- Title:
- R-band polarimetry data in the region of Lupus I
- Short Name:
- J/ApJ/807/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep R-band CCD linear polarimetry collected for fields with lines of sight toward the Lupus I molecular cloud is used to investigate the properties of the magnetic field within this molecular cloud. The observed sample contains about 7000 stars, almost 2000 of them with a polarization signal-to-noise ratio larger than 5. These data cover almost the entire main molecular cloud and also sample two diffuse infrared patches in the neighborhood of Lupus I. The large-scale pattern of the plane-of-sky projection of the magnetic field is perpendicular to the main axis of Lupus I, but parallel to the two diffuse infrared patches. A detailed analysis of our polarization data combined with the Herschel/SPIRE 350{mu}m dust emission map shows that the principal filament of Lupus I is constituted by three main clumps that are acted on by magnetic fields that have different large-scale structural properties. These differences may be the reason for the observed distribution of pre- and protostellar objects along the molecular cloud and the cloud's apparent evolutionary stage. On the other hand, assuming that the magnetic field is composed of large-scale and turbulent components, we find that the latter is rather similar in all three clumps. The estimated plane-of-sky component of the large-scale magnetic field ranges from about 70 to 200{mu}G in these clumps. The intensity increases toward the Galactic plane. The mass-to-magnetic flux ratio is much smaller than unity, implying that Lupus I is magnetically supported on large scales.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A45
- Title:
- R-band polarisation of stars in Gal 110-13 direction
- Short Name:
- J/A+A/588/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out optical polarimetry of an isolated cloud, Gal 110-13, to map the plane-of-the-sky magnetic field geometry. The main aim of the study is to understand the most plausible mechanism responsible for the unusual cometary shape of the cloud in the context of its magnetic field geometry. When unpolarized starlight passes through the intervening interstellar dust grains that are aligned with their short axes parallel to the local magnetic field, it gets linearly polarized. The plane-of-the-sky magnetic field component can therefore be traced by doing polarization measurements of background stars projected on clouds. Because the light in the optical wavelength range is most efficiently polarized by the dust grains typically found in the outer layers of the molecular clouds, optical polarimetry enables us to trace the magnetic field geometry of the outer layers of the clouds. We made R-band polarization measurements of 207 stars in the direction of Gal 110-13. The distance of Gal 110-13 was determined as ~450+/-80pc using our polarization and 2MASS near-infrared data. The foreground interstellar contribution was removed from the observed polarization values by observing a number of stars located in the vicinity of Gal 110-13 which has Hipparcos parallax measurements. The plane-of-the-sky magnetic field lines are found to be well ordered and aligned with the elongated structure of Gal 110-13. Using structure function analysis, we estimated the strength of the plane-of-the-sky component of the magnetic field as ~25{mu}G. Based on our results and comparing them with those from simulations, we conclude that compression by the ionization fronts from 10 Lac is the most plausible cause of the comet-like morphology of Gal 110-13 and of the initiation of subsequent star formation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1609
- Title:
- RCW 106 Giant Molecular Cloud 13CO mapping
- Short Name:
- J/MNRAS/367/1609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first paper in a series detailing the results of ^13^CO observations of a ~1{deg}^2^ region of the giant molecular cloud (GMC) complex associated with the HII region RCW 106. The ^13^CO observations are also the first stage of a multi-molecular line study of the same region. These observations were amongst the first made using the new on-the-fly mapping capability of the Australia Telescope National Facility Mopra Telescope. In the configuration used, the instrument provided a full width at half-maximum (FWHM) beam size of 33arcsec and a velocity resolution of 0.17km/s. The gas emission takes the form of a string of knots, oriented along an axis that extends from the north-west (NW) to the south-east (SE) of the field of the observations, and which is surrounded by a more extended, diffuse emission. We analyse the 2D integrated ^13^CO emission using the CLUMPFIND algorithm and identify 61 clumps. We compare the gas data in the GMC with the dust data provided by 21um Midcourse Space Experiment (MSX) and 1.2mm Swedish European Southern Observatory Submillimetre Telescope (SEST) images that we both regridded to the cell spacing of the Mopra data and smoothed to the same resolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/256
- Title:
- RCW 106 Giant Molecular Cloud NH_3_ emission
- Short Name:
- J/MNRAS/441/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we report observations of the two lowest inversion transitions of ammonia (NH_3_) with the 70-m Tidbinbilla radio telescope. The aim of the observations is to determine the kinetic temperatures in the dense clumps of the G333 giant molecular cloud associated with RCW 106 and to examine the effect that accurate measures of temperature have on the calculation of derived quantities such as mass. This project is part of a larger investigation to understand the time-scales and evolutionary sequence associated with high-mass star formation, particularly its earliest stages. Assuming that the initial chemical composition of a giant molecular cloud is uniform, any abundance variations within will be due to evolutionary state. We have identified 63 clumps using SEST Imaging Bolometer Array 1.2-mm dust continuum maps and have calculated gas temperatures for most (78 per cent) of these dense clumps. After using Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 8.0{mu}m emission to separate the sample into infrared (IR)-bright and IR-faint clumps, we use statistical tests to examine whether our classification shows different populations in terms of mass and temperature.
- ID:
- ivo://CDS.VizieR/J/ApJ/825/91
- Title:
- Refined classification for Orion A protostars
- Short Name:
- J/ApJ/825/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the list of young stellar objects (YSOs) compiled by Megeath et al. (2012, J/AJ/144/192) for the Orion A molecular cloud, only 44 out of 1208 sources found projected onto low extinction (A_K_<0.8mag) gas are identified as protostars. These objects are puzzling because protostars are not typically expected to be associated with extended low extinction material. Here, we use high resolution extinction maps generated from Herschel data, optical/infrared and Spitzer Space Telescope photometry and spectroscopy of the low extinction protostellar candidate sources to determine if they are likely true protostellar sources or contaminants. Out of 44 candidate objects, we determine that 10 sources are likely protostars, with the rest being more evolved YSOs (18), galaxies (4), false detections of nebulosity and cloud edges (9), or real sources for which more data are required to ascertain their nature (3). We find none of the confirmed protostars to be associated with recognizable dense cores and we briefly discuss possible origins for these orphaned objects.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A2
- Title:
- rho Oph region revisited with Gaia EDR3
- Short Name:
- J/A+A/652/A2
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Young and embedded stellar populations are important probes of the star formation process. Their properties and the environments they create have the potential to affect the formation of new planets. Paradoxically, we have a better census of nearby embedded young populations than of the slightly more evolved optically visible young populations. The high accuracy measurements and all-sky coverage of Gaia data are about to change this situation. This work aims to construct the most complete sample to date of YSOs in the {rho} Oph region. We compile a catalog of 1114 Ophiuchus YSOs from the literature and crossmatch it with the Gaia EDR3, Gaia-ESO, and APOGEE-2 surveys. We apply a multivariate classification algorithm to this catalog to identify new, co- moving population candidates. We find 191 high-fidelity new YSO candidates in the Gaia EDR3 catalog belonging to the {rho} Oph region. The new sources appear to be mainly Class III M-stars and substellar objects and are less extincted than the known members, while we find that 28 of previously unknown sources are YSOs with circumstellar disks (Class I or Class II). The analysis of the proper motion distribution of the entire sample reveals a well-defined bimodality, implying two distinct populations sharing a similar 3D volume. The first population comprises young stars' clusters around the {rho} Ophiuchi star and the main Ophiuchus clouds (L1688, L1689, L1709). In contrast, the second population is slightly older (~10Myr), more dispersed, has a distinct proper motion, and is possibly from the Upper-Sco group. The two populations are moving away from each other at about 4.1km/s and will no longer overlap in about 4Myr. Finally, we flag 17 sources in the literature sample as likely impostors, which are sources that exhibit large deviations from the average properties of the {rho} Oph population. Our results show the importance of accurate 3D space and motion information for improved stellar population analysis.
- 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.
