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11. ALMA viewing of OH 231.8+4.2
ID:
ivo://CDS.VizieR/J/A+A/618/A164
Title:
ALMA viewing of OH 231.8+4.2
Short Name:
J/A+A/618/A164
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present continuum and molecular line emission ALMA observations of OH 231.8+4.2, a well studied bipolar nebula around an asymptotic giant branch (AGB) star. The high angular resolution (~0.2"-0.3") and sensitivity of our ALMA maps provide the most detailed and accurate description of the overall nebular structure and kinematics of this object to date. We have identified a number of outflow components previously unknown. Species studied in this work include ^12^CO, ^13^CO, CS, SO, SO_2_, OCS, SiO, SiS, H_3_O^+^, Na^37^Cl, and CH_3_OH. The molecules Na^37^Cl and CH_3_OH are first detections in OH 231.8+4.2, with CH_3_OH being also a first detection in an AGB star.
12. ALMA view of GMCs in NGC 300
ID:
ivo://CDS.VizieR/J/ApJ/857/19
Title:
ALMA view of GMCs in NGC 300
Short Name:
J/ApJ/857/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a ^12^CO(2-1) survey of several molecular gas complexes in the vicinity of HII regions within the spiral galaxy NGC300 using the Atacama Large Millimeter Array (ALMA). Our observations attain a resolution of 10pc and 1km/s, sufficient to fully resolve giant molecular clouds (GMCs) and the highest obtained to date beyond the Local Group. We use the CPROPS algorithm to identify and characterize 250 GMCs across the observed regions. GMCs in NGC300 appear qualitatively and quantitatively similar to those in the Milky Way disk: they show an identical scaling relationship between size R and linewidth {Delta}V ({Delta}V{propto}R^0.48+/-0.05^), appear to be mostly in virial equilibrium, and are consistent with having a constant surface density of about 60M_{sun}_/pc^2^. The GMC mass spectrum is similar to those in the inner disks of spiral galaxies (including the Milky Way). Our results suggest that global galactic properties such as total stellar mass, morphology, and average metallicity may not play a major role in setting GMC properties, at least within the disks of galaxies on the star-forming main sequence. Instead, GMC properties may be more strongly influenced by local environmental factors such as the midplane disk pressure. In particular, in the inner disk of NGC 300, we find this pressure to be similar to that in the local Milky Way but markedly lower than that in the disk of M51, where GMCs are characterized by systematically higher surface densities and a higher coefficient for the size-linewidth relation.
13. A mapping survey of massive CO cores
ID:
ivo://CDS.VizieR/J/MNRAS/391/869
Title:
A mapping survey of massive CO cores
Short Name:
J/MNRAS/391/869
Date:
21 Oct 2021
Publisher:
CDS
Description:
We mapped 21 star-forming regions with the ^12^CO, ^13^CO and C^18^O (1-0) lines using the 13.7-m telescope of Purple Mount Observatory. This mapping survey resolved 53 ^13^CO cores, of which 22 are sourceless. We obtained the physical parameters of these cores. The relation between ^13^CO linewidth and core size and that between column density and core size were analysed. The cores 00211+6549-1 and 22566+5830 were found to have outflows. Systematic VLSR shifts were detected in nine regions: 00211+6549, 00232+6437, 05168+3634, 19199+1358, 20160+3911, 22566+5830, 23042+6000, S146 and S270. Signatures of infall and cloud collision were found in regions 18507+0121 and 19199+1358, respectively. We studied the mass function of these ^13^CO cores. The core masses range from 3.40 to 4.64x10^4^M_{sun}_, and the core mass function is a power-law distribution of index -0.82+/-0.04.
14. A 3mm line survey in 37 IR dark clouds
ID:
ivo://CDS.VizieR/J/ApJ/756/60
Title:
A 3mm line survey in 37 IR dark clouds
Short Name:
J/ApJ/756/60
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have observed 37 Infrared Dark Clouds (IRDCs), containing a total of 159 clumps, in high-density molecular tracers at 3mm using the 22m ATNF Mopra Telescope located in Australia. After determining kinematic distances, we eliminated clumps that are not located in IRDCs and clumps with a separation between them of less than one Mopra beam. Our final sample consists of 92 IRDC clumps. The most commonly detected molecular lines are (detection rates higher than 8%) N_2_H^+^, HNC, HN^13^C, HCO^+^, H^13^CO^+^, HCN, C_2_H, HC_3_N, HNCO, and SiO. We investigate the behavior of the different molecular tracers and look for chemical variations as a function of an evolutionary sequence based on Spitzer IRAC and MIPS emission. Optical depth calculations show that in IRDC clumps the N_2_H^+^ line is optically thin, the C_2_ H line is moderately optically thick, and HNC and HCO^+^ are optically thick.
15. Ammonia in high-mass star formation regions
ID:
ivo://CDS.VizieR/J/ApJ/790/84
Title:
Ammonia in high-mass star formation regions
Short Name:
J/ApJ/790/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report systematic mapping observations of the NH_3_(1, 1) and (2, 2) inversion lines toward 62 high-mass star-forming regions using the Very Large Array (VLA) in its D and DnC array configurations. The VLA images cover a spatial dynamic range from 40'' to 3'', allowing us to trace gas kinematics from ~1 pc scales to <~ 0.1 pc scales. Based on the NH_3_ morphology and the infrared nebulosity on 1 pc scales, we categorize three subclasses in the sample: filaments, hot cores, and NH_3_-dispersed sources. The ubiquitous gas filaments found on 1 pc scales have a typical width of ~0.1 pc and often contain regularly spaced fragments along the major axis. The spacing of the fragments and the column densities is consistent with the turbulent supported fragmentation of cylinders. Several sources show multiple filaments that converge toward a center where the velocity field in the filaments is consistent with gas flows. We derive rotational temperature maps for the entire sample. For the three hot core sources, we find a projected radial temperature distribution that is best fit by power-law indices from -0.18 to -0.35. We identify 174 velocity-coherent ~0.1 pc scale dense cores from the entire sample. The mean physical properties for these cores are 1.1 km/s in intrinsic linewidth, 18 K in NH_3_ rotational temperature, 2.3x10^15^/cm2 in NH_3_gas column density, and 67 M_{sun}_in molecular mass. The dense cores identified from the filamentary sources are closer to being virialized. Dense cores in the other two categories of sources appear to be dynamically unstable.
16. Annotations to the second Planck cluster catalog
ID:
ivo://CDS.VizieR/J/A+A/592/A48
Title:
Annotations to the second Planck cluster catalog
Short Name:
J/A+A/592/A48
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an all sky map of the y-type distortion calculated from the full mission Planck HFI (High Frequency Instrument) data using the recently proposed approach to component separation based on parametric model fitting and model selection. This simple model selection approach allows us to distinguish between carbon monoxide (CO) line emission and y-type distortion, something that is not possible using the internal linear combination based methods. We create a mask to cover the regions of significant CO emission relying on the information in the {chi}^2^ map obtained when fitting for the y-distortion and CO emission to the lowest four HFI channels. We revisit the second Planck cluster catalog and try to quantify the quality of the cluster candidates in an approach that is similar in spirit to Aghanim et al. (2015A&A...580A.138A). We find that at least 93% of the clusters in the cosmology sample are free of CO contamination. We also find that 59% of unconfirmed candidates may have significant contamination from molecular clouds. We agree with Planck Collaboration et al. (2016, A&A, in press., arXiv:1502.01598) for the worst offenders. We suggest an alternative validation strategy of measuring and subtracting the CO emission from the Planck cluster candidates using radio telescopes thus improving the reliability of the catalog. Our CO mask and annotations to the Planck cluster catalog identifying cluster candidates with possible CO contamination are made publicly available.
17. APEX observations of HOPS protostars
ID:
ivo://CDS.VizieR/J/ApJ/767/36
Title:
APEX observations of HOPS protostars
Short Name:
J/ApJ/767/36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument on board the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel Orion Protostar Survey (HOPS). A total of 55 new protostar candidates are detected at 70{mu}m and 160{mu}m that are either too faint (m_24_>7mag) to be reliably classified as protostars or undetected in the Spitzer/MIPS 24{mu}m band. We find that the 11 reddest protostar candidates with log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65 are free of contamination and can thus be reliably explained as protostars. The remaining 44 sources have less extreme 70/24 colors, fainter 70{mu}m fluxes, and higher levels of contamination. Taking the previously known sample of Spitzer protostars and the new sample together, we find 18 sources that have log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65; we name these sources "PACS Bright Red sources," or PBRs. Our analysis reveals that the PBR sample is composed of Class 0 like sources characterized by very red spectral energy distributions (SEDs; T_bol_<45K) and large values of sub-millimeter fluxes (L_smm_/L_bol_>0.6%). Modified blackbody fits to the SEDs provide lower limits to the envelope masses of 0.2-2M_{sun}_ and luminosities of 0.7-10L_{sun}_. Based on these properties, and a comparison of the SEDs with radiative transfer models of protostars, we conclude that the PBRs are most likely extreme Class 0 objects distinguished by higher than typical envelope densities and hence, high mass infall rates.
18. APOGEE-2 survey of Orion Complex. II.
ID:
ivo://CDS.VizieR/J/AJ/156/84
Title:
APOGEE-2 survey of Orion Complex. II.
Short Name:
J/AJ/156/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of spectroscopic and astrometric data from APOGEE-2 and Gaia DR2 (Cat. I/345) to identify structures toward the Orion Complex. By applying a hierarchical clustering algorithm to the six-dimensional stellar data, we identify spatially and/or kinematically distinct groups of young stellar objects with ages ranging from 1 to 12 Myr. We also investigate the star-forming history within the Orion Complex and identify peculiar subclusters. With this method we reconstruct the older populations in the regions that are currently largely devoid of molecular gas, such as Orion C (which includes the {sigma} Ori cluster) and Orion D (the population that traces Ori OB1a, OB1b, and Orion X). We report on the distances, kinematics, and ages of the groups within the Complex. The Orion D group is in the process of expanding. On the other hand, Orion B is still in the process of contraction. In {lambda} Ori the proper motions are consistent with a radial expansion due to an explosion from a supernova; the traceback age from the expansion exceeds the age of the youngest stars formed near the outer edges of the region, and their formation would have been triggered when they were halfway from the cluster center to their current positions. We also present a comparison between the parallax and proper-motion solutions obtained by Gaia DR2 and those obtained toward star-forming regions by the Very Long Baseline Array.
19. APOGEE-2 survey of Orion Complex (OSFC). I.
ID:
ivo://CDS.VizieR/J/ApJS/236/27
Title:
APOGEE-2 survey of Orion Complex (OSFC). I.
Short Name:
J/ApJS/236/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Orion Star-forming Complex (OSFC) is a central target for the APOGEE-2 Young Cluster Survey. Existing membership catalogs span limited portions of the OSFC, reflecting the difficulty of selecting targets homogeneously across this extended, highly structured region. We have used data from wide-field photometric surveys to produce a less biased parent sample of young stellar objects (YSOs) with infrared (IR) excesses indicative of warm circumstellar material or photometric variability at optical wavelengths across the full 420deg^2^ extent of the OSFC. When restricted to YSO candidates with H<12.4, to ensure S/N~100 for a six-visit source, this uniformly selected sample includes 1307 IR excess sources selected using criteria vetted by Koenig & Leisawitz (2014ApJ...791..131K) and 990 optical variables identified in the Pan-STARRS1 3{pi} survey: 319 sources exhibit both optical variability and evidence of circumstellar disks through IR excess. Objects from this uniformly selected sample received the highest priority for targeting, but required fewer than half of the fibers on each APOGEE-2 plate. We filled the remaining fibers with previously confirmed and new color-magnitude selected candidate OSFC members. Radial velocity measurements from APOGEE-1 and new APOGEE-2 observations taken in the survey's first year indicate that ~90% of the uniformly selected targets have radial velocities consistent with Orion membership. The APOGEE-2 Orion survey will include >1100 bona fide YSOs whose uniform selection function will provide a robust sample for comparative analyses of the stellar populations and properties across all sub-regions of Orion.
20. Arecibo 21cm obs. of sources in 5 GMC regions
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.

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