- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/612/A117
- Title:
- CO isotopes towards Galactic YSOs and HII regions
- Short Name:
- J/A+A/612/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aims. Determining molecular abundance ratios is important not only for the study of Galactic chemistry, but also because they are useful to estimate physical parameters in a large variety of interstellar medium environments. One of the most important molecules for tracing the molecular gas in the interstellar medium is CO, and the ^13^CO/C^18^O abundance ratio is usually used to estimate molecular masses and densities of regions with moderate to high densities. Nowadays isotope ratios are in general indirectly derived from elemental abundances ratios. We present the first ^13^CO/C^18^O abundance ratio study performed from CO isotope observations towards a large sample of Galactic sources of different natures at different locations. Methods. To study the ^13^CO/C^18^O abundance ratio, we used ^12^CO J=3-2 data obtained from the CO High-Resolution Survey, ^13^CO and C^18^O J=3-2 data from the ^13^CO/C^18^O (J=3-2) Heterodyne Inner Milky Way Plane Survey, and some complementary data extracted from the James Clerk Maxwell Telescope database. We analyzed a sample of 198 sources composed of young stellar objects (YSOs), and HII and diffuse HII regions as catalogued in the Red MSX Source Survey in 27.5{deg}<=l<=46.5{deg} and |b|<0.5{deg}. Results. Most of the analyzed sources are located in the galactocentric distance range 4.0-6.5kpc. We found that YSOs have, on average, lower ^13^CO/C^18^O abundance ratios than HII and diffuse HII regions. Taking into account that the gas associated with YSOs should be less affected by the radiation than in the case of the others sources, selective far-UV photodissociation of C^18^O is confirmed. The ^13^CO/C^18^O abundance ratios obtained in this work are systematically lower than those predicted from the known elemental abundance relations. These results will be useful in future studies of molecular gas related to YSOs and HII regions based on the observation of these isotopes.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/13
- Title:
- Co I transition probabilities
- Short Name:
- J/ApJS/220/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New emission branching fraction measurements for 898 lines of the first spectrum of cobalt (Co I) are determined from hollow cathode lamp spectra recorded with the National Solar Observatory 1m Fourier transform spectrometer on Kitt Peak, AZ and a high-resolution echelle spectrometer. Published radiative lifetimes from laser induced fluorescence measurements are combined with the branching fractions to determine accurate absolute atomic transition probabilities for the 898 lines. Hyperfine structure (hfs) constants for levels of neutral Co in the literature are surveyed and selected values are used to generate complete hfs component patterns for 195 transitions of Co I. These new laboratory data are applied to determine the Co abundance in the Sun and metal-poor star HD 84937, yielding log{epsilon}(Co)=4.955+/-0.007 ({sigma}=0.059) based on 82 Co I lines and log{epsilon}(Co)=2.785+/-0.008 ({sigma}=0.065) based on 66 Co I lines, respectively. A Saha or ionization balance test on the photosphere of HD 84937 is performed using 16 UV lines of Co II, and good agreement is found with the Co I result in this metal-poor ([FeI/H]=-2.32, [FeII/H]=-2.32) dwarf star. The resulting value of [Co/Fe]=+0.14 supports a rise of Co/Fe at low metallicity that has been suggested in other studies.
- 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.
- 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.
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/157/228
- Title:
- Cold Classical TNOs: LCs & rotational properties
- Short Name:
- J/AJ/157/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey of the rotational and physical properties of the dynamically low inclination Cold Classical (CC) trans-Neptunian objects (TNOs). The CCs are primordial planetesimals and contain information about our solar system and planet formation over the first 100 million years after the Sun's formation. We obtained partial/complete light curves for 42 CCs. We use statistical tests to derive general properties about the shape and rotational frequency distributions of the CCs and infer that they have slower rotations and are more elongated/deformed than the other TNOs. On the basis of the full light curves, the mean rotational period of the CCs is 9.48+/-1.53 hr compared to 8.45+/-0.58 hr for the rest of the TNOs. About 65% of the TNOs have a light-curve amplitude below 0.2 mag compared to the 36% of CCs with small amplitude. We present the full light curve of one likely contact binary, 2004 VC_131_, with a potential density of 1 g/cm^3^ for a mass ratio of 0.4. We have hints that 2004 MU_8_ and 2004 VU_75_ are perhaps potential contact binaries, on the basis of their sparse light curves, but more data are needed to confirm this finding. Assuming equal-sized binaries, we find that ~10%-25% of the CCs could be contact binaries, suggesting a deficit of contact binaries in this population compared to previous estimates and to the (~40%-50%) possible contact binaries in the Plutino population. These estimates are lower limits and may increase if nonequal-sized contact binaries are considered. Finally, we put in context the results of the New Horizons flyby of 2014 MU_69_.
3990. 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.
