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3061. CO in extragalactic giant molecular clouds
ID:
ivo://CDS.VizieR/J/ApJ/686/948
Title:
CO in extragalactic giant molecular clouds
Short Name:
J/ApJ/686/948
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use high spatial resolution observations of CO to systematically measure the resolved size-line width, luminosity-line width, luminosity-size, and mass-luminosity relations of GMCs in a variety of extragalactic systems. Although the data are heterogeneous, we analyze them in a consistent manner to remove the biases introduced by limited sensitivity and resolution, thus obtaining reliable sizes, velocity dispersions, and luminosities. We compare the results obtained in dwarf galaxies with those from the Local Group spiral galaxies. We find that extragalactic GMC properties measured across a wide range of environments are very much compatible with those in the Galaxy. The property that shows the largest variability is their resolved brightness temperature, although even that is similar to the average Galactic value in most sources.
3062. CO in Galactic HII regions
ID:
ivo://CDS.VizieR/J/ApJS/181/255
Title:
CO in Galactic HII regions
Short Name:
J/ApJS/181/255
Date:
21 Oct 2021
Publisher:
CDS
Description:
We derive the molecular properties for a sample of 301 Galactic HII regions including 123 ultra compact (UC), 105 compact, and 73 diffuse nebulae. We analyze all sources within the BU-FCRAO Galactic Ring Survey (GRS) of ^13^CO emission known to be HII regions based upon the presence of radio continuum and cm-wavelength radio recombination line emission. Unlike all previous large area coverage ^13^CO surveys, the GRS is fully sampled in angle and yet covers ~75deg^2^ of the Inner Galaxy. The angular resolution of the GRS (46") allows us to associate molecular gas with HII regions without ambiguity and to investigate the physical properties of this molecular gas. We find clear CO/HII morphological associations in position and velocity for ~80% of the nebular sample. Compact HII region molecular gas clouds are on average larger than UC clouds: 2.2' compared to 1.7'.
3063. CO in HCG galaxies with enhanced warm H_2_
ID:
ivo://CDS.VizieR/J/A+A/570/A24
Title:
CO in HCG galaxies with enhanced warm H_2_
Short Name:
J/A+A/570/A24
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galaxies in Hickson Compact Groups (HCGs) are believed to experience morphological transformations from blue, star-forming galaxies to red, early-type galaxies. Galaxies with a high ratio between the luminosities of the warm H_2_ to the 7.7micron PAH emission (so-called Molecular Hydrogen Emission Galaxies, MOHEGs) are predominantly in an intermediate phase, the green valley. Their enhanced H_2_ emission suggests that the molecular gas is affected in the transition. We study the properties of the molecular gas traced by CO in galaxies in HCGs with measured warm H_2_ emission in order to look for evidence of the perturbations affecting the warm H_2_ in the kinematics, morphology and mass of the molecular gas. We observed the CO(1-0) emission of 20 galaxies in HCGs and complemented our sample with 11 CO(1-0) spectra from the literature. Most of the galaxies have measured} warm H_2_ emission, and 14 of them are classified as MOHEGs. We mapped some of these galaxies in order to search for extra-galactic CO emission. We analyzed the molecular gas mass derived from CO(1-0), MH_2_, and its kinematics, and then compared it to the mass of the warm molecular gas, the stellar mass and star formation rate (SFR). Our results are the following. (i) The mass ratio between the CO-derived and the warm H_2_ molecular gas is in the same range as found for field galaxies. (ii) Some of the galaxies, mostly MOHEGs, have very broad CO linewidths of up to 1000km/s in the central pointing. The line shapes are irregular and show various components. (iii) In the mapped objects we found asymmetric distributions of the cold molecular gas. (iv) The star formation efficiency (=SFR/MH_2_) of galaxies in HCGs is very similar to isolated galaxies. No significant difference between MOHEGs and non-MOHEGs or between early-type and spiral galaxies has been found. In a few objects the SFE is significantly lower, indicating the presence of molecular gas that is not actively forming stars. (v) The molecular gas masses, MH_2_, and ratios MH_2_/Lk are lower in MOHEGs (predominantly early-types) than in non-MOHEGs (predominantly spirals). This trend remains when comparing MOHEGs and non-MOHEGs of the same morphological type. We found differences in the molecular gas properties of MOHEGs that support the view that they have suffered (or are presently suffering) perturbations of the molecular gas, as well as a decrease in the molecular gas content and associated SFR. Higher resolution observations of the molecular gas are needed to shed light on the nature of these perturbations and their cause.
3064. CO in Protostars (COPS): Herschel spectroscopy
ID:
ivo://CDS.VizieR/J/ApJ/860/174
Title:
CO in Protostars (COPS): Herschel spectroscopy
Short Name:
J/ApJ/860/174
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present full spectral scans from 200 to 670{mu}m of 26 Class 0+I protostellar sources obtained with Herschel-SPIRE as part of the "COPS-SPIRE" Open Time program, complementary to the DIGIT and WISH Key Programs. Based on our nearly continuous, line-free spectra from 200 to 670{mu}m, the calculated bolometric luminosities (Lbol) increase by 50% on average, and the bolometric temperatures (Tbol) decrease by 10% on average, in comparison with the measurements without Herschel. Fifteen protostars have the same class using Tbol and Lbol/Lsmm. We identify rotational transitions of CO lines from J=4->3 to J=13->12, along with emission lines of ^13^CO, HCO^+^, H_2_O, and [CI]. The ratios of ^12^CO to ^13^CO indicate that ^12^CO emission remains optically thick for J_up_<13. We fit up to four components of temperature from the rotational diagram with flexible break points to separate the components. The distribution of rotational temperatures shows a primary population around 100K with a secondary population at ~350K. We quantify the correlations of each line pair found in our data set and find that the strength of the correlation of CO lines decreases as the difference between J levels between two CO lines increases. The multiple origins of CO emission previously revealed by velocity-resolved profiles are consistent with this smooth distribution if each physical component contributes to a wide range of CO lines with significant overlap in the CO ladder. We investigate the spatial extent of CO emission and find that the morphology is more centrally peaked and less bipolar at high-J lines. We find the CO emission observed with SPIRE related to outflows, which consists of two components, the entrained gas and shocked gas, as revealed by our rotational diagram analysis, as well as the studies with velocity-resolved CO emission.
3065. 12CO J=3-2 datacube toward N11
ID:
ivo://CDS.VizieR/J/A+A/628/A96
Title:
12CO J=3-2 datacube toward N11
Short Name:
J/A+A/628/A96
Date:
21 Oct 2021
Publisher:
CDS
Description:
After 30 Doradus, N11 is the second largest and brightest nebula in the Large Magellanic Cloud (LMC). This large nebula has several OB associations with bright nebulae at its surroundings. N11 was previously mapped at the lowest rotational transitions of ^12^CO (J=1-0 and 2-1), and in some particular regions, pointings of the ^13^ CO J=1-0 and 2-1 lines were also performed. Observationsof higher CO rotational transitions are needed to map gas with higher critical densities, which are useful to study the physical conditions of the gas component and its relation with the UV radiation more accurately. Using the Atacama Submillimeter Telescope Experiment, we mapped the whole extension of the N11 nebula in the ^12^CO J=3-2 line and three subregions in the ^13^CO J=3-2 line. The regions mapped in the ^13^CO J=3-2 were selected with the criterion that they were to be exposed to the radiation in different ways: a region lying across the nebula, which is related to the OB association LH10 (N11B), another region that it is associated with the southern part of the nebula, which is related to the OB association LH13 (N11D), and finally an area farther away in the southwest without any embedded OB association (N11I) We found that the morphology of the molecular clouds lying in each region shows some signatures that could be explained by the expansion of the nebulae and the action of the radiation. Fragmentation generated in a molecular shell due to the expansion of the N11 nebula is suggested. The integrated line ratios ^12^CO/^13^CO show evidence of selective photodissociation of the ^13^CO, and probably other mechanisms such as chemical fractionation. The values found for the integrated line ratios ^12^CO J=3-2/1-0 are in agreement with values that were assumed in previous works, and the CO contribution to the continuum at 870um was derived directly. The distribution of the integrated line ratios ^12^CO J=3-2/2-1 show indications of stellar feedback in N11B and N11D. The ratio between the virial and local thermal equilibrium (LTE) mass (M_vir_/M_LTE_) is higher than unity in all analyzed molecular clumps, which suggests that the clumps are not gravitationally bounded and may be supported by external pressure. A non-LTE analysis suggests that we map gas with densities of about a few 10^3^cm^-3^. The molecular clump at N11B, the unique molecular feature with direct evidence of ongoing star formation, is the densest of the clumps we analyzed.
3066. CO (J=1-0) data of cold IRAS sources
ID:
ivo://CDS.VizieR/J/ApJS/141/157
Title:
CO (J=1-0) data of cold IRAS sources
Short Name:
J/ApJS/141/157
Date:
21 Oct 2021
Publisher:
CDS
Description:
We conducted a large-scale survey for the cold infrared sources along the northern Galactic plane in the CO (J=1-0) line. There are 1912 IRAS sources selected on the basis of their color indices over the 12, 25, and 60{mu}m wave bands and their association with regions of recent star formation. A quick single-point survey was made toward all of the sources, which results in a detection of 1331 sources with significant CO emission above the detection limit of 0.7K, inferring a CO detection rate of 70%. Located over a wide range of the Galactocentric distances, the CO sources show high concentration toward the spiral arms. Among the detected sources, there are 351 sources found to have high-velocity CO wing emission. A search for the latest catalog of high-velocity CO flows (HVFs) from young stellar objects indicates that 289 sources are beyond the present lists of HVFs. These high-velocity wing sources provide us with a comprehensive database for the study of HVFs from young stellar objects. Using the known outflow sources as an effective indicator, we found that the detection rate for high-velocity wings during the quick survey is 62%, moderately sensitive in searching for new outflow sources. The CO detection rate of the IRAS sources, combined with the ratio of high-velocity wing, suggests that 41% of the CO sources are undergoing the HVF phase. In this paper, the CO spectra are presented along with the preliminary statistics of the data.
3067. CO J=2-1 NOEMA observations of mu Cep
ID:
ivo://CDS.VizieR/J/MNRAS/485/2417
Title:
CO J=2-1 NOEMA observations of mu Cep
Short Name:
J/MNRAS/485/2417
Date:
21 Oct 2021
Publisher:
CDS
Description:
Red supergiant stars are surrounded by a gaseous and dusty circumstellar environment created by their mass loss which spreads heavy elements into the interstellar medium. The structure and the dynamics of this envelope are crucial to understand the processes driving the red supergiant mass loss and the shaping of the pre-supernova ejecta. We have observed the emission from the CO J=2-1 line from the red supergiant star {mu} Cep with the NOEMA interferometer. In the line the synthesized beam was 0.92x0.72-arcsec (590x462au at 641pc). The continuum map shows only the unresolved contribution of the free-free emission of the star chromosphere. The continuum-subtracted channel maps reveal a very inhomogeneous and clumpy circumstellar environment. In particular, we detected a bright CO clump, as bright as the central source in the line, at 1.80-arcsec south-west from the star, in the blue channel maps. After a deprojection of the radial velocity assuming two different constant wind velocities, the observations were modelled using the 3D radiative transfer code LIME to derive the characteristics of the different structures. We determine that the gaseous clumps observed around {mu} Cep are responsible for a mass loss rate of (4.9+/-1.0)x10^-7^M_[sun}_/yr, in addition to a spatially unresolved wind component with an estimated mass-loss rate of 2.0x10^-6^M_[sun}_/yr. Therefore, the clumps have a significant role in {mu} Cep's mass loss (>=25%). We cannot exclude that the unresolved central outflow may be made of smaller unresolved clumps.
3068. COLA. III. AGN in compact IR galaxies
ID:
ivo://CDS.VizieR/J/ApJ/720/555
Title:
COLA. III. AGN in compact IR galaxies
Short Name:
J/ApJ/720/555
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from 4.8GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_IR_=10^11.01^L_{sun}_) COLA (Compact Objects in Low-power AGNs) sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^21^W/Hz) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
3069. CO large-field observations around l=150{deg}
ID:
ivo://CDS.VizieR/J/ApJ/838/49
Title:
CO large-field observations around l=150{deg}
Short Name:
J/ApJ/838/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present large-field (4.25x3.75deg^2^) mapping observations toward the Galactic region centered at l=150{deg},b=3.5{deg} in the J=1-0 emission line of CO isotopologues (^12^CO, ^13^CO, and C^18^O), using the 13.7m millimeter-wavelength telescope of the Purple Mountain Observatory. Based on the ^13^CO observations, we reveal a filamentary cloud in the Local Arm at a velocity range of -0.5 to 6.5km/s. This molecular cloud contains 1 main filament and 11 sub-filaments, showing the so-called "ridge-nest" structure. The main filament and three sub-filaments are also detected in the C^18^O line. The velocity structures of most identified filaments display continuous distribution with slight velocity gradients. The measured median excitation temperature, line width, length, width, and linear mass of the filaments are ~9.28K, 0.85km/s, 7.30pc, 0.79pc, and 17.92M_{sun}_/pc, respectively, assuming a distance of 400pc. We find that the four filaments detected in the C^18^O line are thermally supercritical, and two of them are in the virialized state, and thus tend to be gravitationally bound. We identify in total 146 ^13^CO clumps in the cloud, about 77% of the clumps are distributed along the filaments. About 56% of the virialized clumps are found to be associated with the supercritical filaments. Three young stellar object candidates are also identified in the supercritical filaments, based on the complementary infrared data. These results indicate that the supercritical filaments, especially the virialized filaments, may contain star-forming activities.
3070. Cold galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/453/2050
Title:
Cold galaxies
Short Name:
J/MNRAS/453/2050
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use 350 {mu}m angular diameter estimates from Planck to test the idea that some galaxies contain exceptionally cold (10-13 K) dust, since colder dust implies a lower surface brightness radiation field illuminating the dust, and hence a greater physical extent for a given luminosity. The galaxies identified from their spectral energy distributions as containing cold dust do indeed show the expected larger 350 {mu}m diameters. For a few cold dust galaxies where Herschel data are available, we are able to use submillimetre maps or surface brightness profiles to locate the cold dust, which as expected generally lies outside the optical galaxy.

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