- ID:
- ivo://CDS.VizieR/J/A+A/632/A106
- Title:
- LMC-N11 (LHA 120-N11) [CII], HI, CO spectra
- Short Name:
- J/A+A/632/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ambiguous origin of the [CII] 158um line in the interstellar medium complicates its use for diagnostics concerning the star-formation rate and physical conditions in photodissociation regions. We investigate the origin of [CII] in order to measure the total molecular gas content, the fraction of CO-dark H_2_ gas, and how these parameters are impacted by environmental effects such as stellar feedback. We observed the giant HII region N 11 in the Large Magellanic Cloud with SOFIA/GREAT. The [CII] line is resolved in velocity and compared to HI and CO, using a Bayesian approach to decompose the line profiles. A simple model accounting for collisions in the neutral atomic and molecular gas was used in order to derive the H_2_ column density traced by C^+^. The profile of [CII] most closely resembles that of CO, but the integrated [CII] line width lies between that of CO and that of HI. Using various methods, we find that [CII] mostly originates from the neutral gas. We show that [CII] mostly traces the CO-dark H_2_ gas but there is evidence of a weak contribution from neutral atomic gas preferentially in the faintest components (as opposed to components with low [CII]/CO or low CO column density). Most of the molecular gas is CO-dark. The CO-dark H_2_ gas, whose density is typically a few 100s/cm^3^ and thermal pressure in the range 10^3.5-5^K/cm^3^, is not always in pressure equilibrium with the neutral atomic gas. The fraction of CO-dark H_2_ gas decreases with increasing CO column density, with a slope that seems to depend on the impinging radiation field from nearby massive stars. Finally we extend previous measurements of the photoelectric-effect heating efficiency, which we find is constant across regions probed with Herschel, with [CII] and [OI] being the main coolants in faint and diffuse, and bright and compact regions, respectively, and with polycyclic aromatic hydrocarbon emission tracing the CO-dark H_2_ gas heating where [CII] and [OI] emit. We present an innovative spectral decomposition method that allows statistical trends to be derived for the molecular gas content using CO, [CII], and HI profiles. Our study highlights the importance of velocity-resolved photodissociation region (PDR) diagnostics and higher spatial resolution for HI observations as future steps.
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Search Results
- ID:
- ivo://CDS.VizieR/VII/114
- Title:
- Massachusetts-Stony Brook Galactic Plane CO Survey
- Short Name:
- VII/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Massachusetts-Stony Brook Galactic Plane CO Survey data consists of 40551 12CO(J=1-0) spectra covering Galactic longitudes 8-90 deg and latitudes -1.05 to +1 deg. The spectra were obtained with the 14m antenna at the Five College Radio Astronomy Observatory. Each spectrum consists of 350 channels with 1km/s width; up to 300 channels per spectrum are defined. The extra channels allow for shifts of the central velocity with longitude to keep the Galactic emission within the frequency range of the backend. The spectra have RMS noise of 0.4K per channel and intensities are on the T(R)* scale. The spectra were taken on a 3'x3' grid for longitudes between 18 deg and 55 deg. At other longitudes, the grid spacing was 6'x6'. The data are in 3-dimensional FITS files; the axes are LSR velocity, latitude, and longitude.
- ID:
- ivo://CDS.VizieR/J/A+A/380/665
- Title:
- Massive dense cores with ^13^CO J=1-0 lines
- Short Name:
- J/A+A/380/665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports ^13^CO J=1-0 line observations toward 107 IRAS or H2O maser sources with the 13.7m telescope of the Purple Mountain Observatory (PMO). Parameters of emission components are obtained and the profile characteristics are identified. Table1 lists the observed results. It contains source name and its coordinates. ^13^CO line parameters and profile characteristics are given out. Distance, IRAS color indices and bolometric luminosity are also presented.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/645
- Title:
- Massive molecular outflows distance-limited sample
- Short Name:
- J/MNRAS/453/645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 99 mid-infrared-bright, massive young stellar objects and compact HII regions drawn from the Red MSX source survey in the J=3-2 transition of ^12^CO and ^13^CO, using the James Clerk Maxwell Telescope. 89 targets are within 6kpc of the Sun, covering a representative range of luminosities and core masses. These constitute a relatively unbiased sample of bipolar molecular outflows associated with massive star formation. Of these, 59, 17 and 13 sources (66, 19 and 15 percent) are found to have outflows, show some evidence of outflow, and have no evidence of outflow, respectively. The time-dependent parameters of the high-velocity molecular flows are calculated using a spatially variable dynamic time-scale. The canonical correlations between the outflow parameters and source luminosity are recovered and shown to scale with those of low-mass sources. For coeval star formation, we find the scaling is consistent with all the protostars in an embedded cluster providing the outflow force, with massive stars up to ~30M_{sun}_ generating outflows. Taken at face value, the results support the model of a scaled-up version of the accretion-related outflow-generation mechanism associated with discs and jets in low-mass objects with time-averaged accretion rates of ~ 10^-3^M_{sun}_/yr on to the cores. However, we also suggest an alternative model, in which the molecular outflow dynamics are dominated by the entrained mass and are unrelated to the details of the acceleration mechanism. We find no evidence that outflows contribute significantly to the turbulent kinetic energy of the surrounding dense cores.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/3
- Title:
- Massive outflows associated with ATLASGAL clumps
- Short Name:
- J/ApJS/235/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken the largest survey for outflows within the Galactic plane using simultaneously observed ^13^CO and C^18^O data. Out of a total of 919 ATLASGAL clumps, 328 have data suitable to identify outflows, and 228 (69%+/-3%) show high-velocity outflows. The clumps with detected outflows show significantly higher clump masses (M_clump_), bolometric luminosities (L_bol_), luminosity-to-mass ratios (L_bol_/M_clump_), and peak H_2_ column densities (N_H2_) compared to those without outflows. Outflow activity has been detected within the youngest quiescent clump (i.e., 70{mu}m weak) in this sample, and we find that the outflow detection rate increases with M_clump_, L_bol_, L_bol_/M_clump_, and N_H2_, approaching 90% in some cases (UC HII regions = 93%+/-3%; masers = 86%+/-4%; HC HII regions = 100%). This high detection rate suggests that outflows are ubiquitous phenomena of massive star formation (MSF). The mean outflow mass entrainment rate implies a mean accretion rate of ~10^-4^M_{sun}_/yr, in full agreement with the accretion rate predicted by theoretical models of MSF. Outflow properties are tightly correlated with M_clump_, L_bol_, and L_bol_/M_clump_ and show the strongest relation with the bolometric clump luminosity. This suggests that outflows might be driven by the most massive and luminous source within the clump. The correlations are similar for both low-mass and high-mass outflows over 7 orders of magnitude, indicating that they may share a similar outflow mechanism. Outflow energy is comparable to the turbulent energy within the clump; however, we find no evidence that outflows increase the level of clump turbulence as the clumps evolve. This implies that the origin of turbulence within clumps is fixed before the onset of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/876/70
- Title:
- Massive YSOs in the IR dark cloud G79.3+0.3
- Short Name:
- J/ApJ/876/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- G79.3+0.3 is an infrared dark cloud in the Cygnus-X complex that is home to massive deeply embedded young stellar objects (YSOs). We have produced a Submillimeter Array (SMA) 1.3mm continuum image and ^12^CO line maps of the eastern section of G79.3+0.3 in which we detect five separate YSOs. We have estimated physical parameters for these five YSOs and others in the vicinity of G79.3+0.3 by fitting existing photometry from Spitzer, Herschel, and ground-based telescopes to spectral energy distribution models. Through these model fits we find that the most massive YSOs seen in the SMA 1.3mm continuum emission have masses in the 5-6M_{sun}_ range. One of the SMA sources was observed to power a massive collimated ^12^CO outflow extending at least 0.94pc in both directions from the protostar, with a total mass of 0.83M_{sun}_ and a dynamical timescale of 23kyr.
- ID:
- ivo://CDS.VizieR/J/A+A/522/A3
- Title:
- M33 CO(2-1) and HI integrated intensity maps
- Short Name:
- J/A+A/522/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30m IRAM telescope in the CO(2-1) line, achieving a resolution of 12"x2.6km/s, enabling individual giant molecular clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5kpc, and covers entirely the 2'x40' radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main-beam temperature is 20-50mK at 2.6km/s velocity resolution. The CO(2-1) luminosity of the observed region is 1.7+/-0.1x10^7^K.km/s.pc^2^ and is estimated to be 2.8+/-0.3x10^7^K.km/s.pc^2^ for the entire galaxy, corresponding to H_2_ masses of 1.9x10^8^ and 3.3x10^8^ respectively (including He), calculated with N(H_2_)/I_CO_(1-0) twice the Galactic value due to the half-solar metallicity of M 33. The HI 21cm VLA archive observations were reduced, and the mosaic was imaged and cleaned using the multi-scale task in the CASA software package, yielding a series of datacube with resolutions ranging from 5" to 25". The HI mass within a radius of 8.5kpc is estimated to be 1.4x10^9^. The azimuthally averaged CO surface brightness decreases exponentially with a scale length of 1.9+/-0.1kpc whereas the atomicgas surface density is constant at {Sigma}_HI_=6+/-2pc^-2^ deprojected to face-on. For an (H_2_)/I_CO_(1-0) conversion factor twice that of the Milky Way, the central kiloparsec H2 surface density is {Sigma}_HI_=8.5+/-0.2pc^-2^. The star formation rate per unit moecular gas (SF efficiency, the rate of transformation of molecular gas into stars), as traced by the ratio of CO to H{alpha} and FIR brightness, is constant with radus. The SFE, with a N(H2)/I_CO_(1-0) factor twice galactic, appears 2-4 times greater than for large spiral galaxies. A morphological comparison of molecular and atomic gas with tracers of star formation is presented showing good agreement between these maps both in terms of peaks and holes. A few exceptions are noted. Several spectra, including those of a molecular cloud situated more than 8kpc from the galaxy center, are presented.
118. M16 CO maps
- ID:
- ivo://CDS.VizieR/J/A+A/627/A27
- Title:
- M16 CO maps
- Short Name:
- J/A+A/627/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to investigate the impact of the ionized radiation from the M16 HII region on the surrounding molecular cloud and on its hosted star formation. To present comprehensive multi-wavelength observations towards the M16 HII region, we used new CO data and existing infrared, optical, and submillimeter data. The ^12^CO J=1-0, ^13^CO J=1-0, and C^18^O J=1-0 data were obtained with the Purple Mountain Observatory (PMO) 13.7m radio telescope. To trace massive clumps and extract young stellar objects (YSOs) associated with the M16 HII region, we used the ATLASGAL and GLIMPSE I catalogs, respectively. From CO data, we discern a large-scale filament with three velocity components. Because these three components overlap with each other in both velocity and space, the filament may be made of three layers. The M16 ionized gas interacts with the largescale filament and has reshaped its structure. In the large-scale filament, we find 51 compact cores from the ATLASGAL catalog, 20 of them being quiescent. The mean excitation temperature of these cores is 22.5K, while this is 22.2K for the quiescent cores. This high temperature observed for the quiescent cores suggests that the cores may be heated by M16 and do not experience internal heating from sources in the cores. Through the relationship between the mass and radius of these cores, we obtain that 45% of all the cores are massive enough to potentially form massive stars. Compared with the thermal motion, the turbulence created by the nonthermal motion is responsible for the core formation. For the pillars observed towards M16, the H II region may give rise to the strong turbulence.
119. M31 CO(2-1) spectra
- ID:
- ivo://CDS.VizieR/J/A+A/549/A27
- Title:
- M31 CO(2-1) spectra
- Short Name:
- J/A+A/549/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With IRAM-30m/HERA, we have detected CO(2-1) gas complexes within 30arcsec (100pc) from the center of M31 that amount to a minimum total mass of 4.2x10^4^M_{sun}_ (one third of the positions are detected). Averaging the whole HERA field, we show that there is no additional undetected diffuse component. Moreover, the gas detection is associated with gas lying on the far side of the M31 center as no extinction is observed in the optical, but some emission is present on infrared Spitzer maps. The kinematics is complex. (1) The velocity pattern is mainly redshifted: the dynamical center of the gas differs from the black hole position and the maximum of optical emission, and only the redshifted side is seen in our data. (2) Several velocity components are detected in some lines of sight. Our interpretation is supported by the reanalysis of the effect of dust on a complete planetary nebula sample. Two dust components are detected with respective position angles of 37deg and -66deg. This is compatible with a scenario where the superposition of the (PA=37deg) disk is dominated by the 10kpc ring and the inner 0.7kpc ring detected in infrared data, whose position angle (-66deg) we measured for the first time. The large-scale disk, which dominates the HI data, is steeply inclined (i=77deg), warped and superposed on the line of sight on the less inclined inner ring. The detected CO emission might come from both components.
- 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.
