- 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.
Number of results to display per page
Search Results
- 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.
- 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/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/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/A+A/564/A65
- Title:
- Cold gas properties of Herschel Reference Survey
- Short Name:
- J/A+A/564/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new ^12^CO(1-0) observations of 59 late-type galaxies belonging to the Herschel Reference Survey (HRS), a complete K-band-selected, volume-limited (15<=D<=25Mpc) sample of nearby galaxies spanning a wide range in morphological type and luminosity. We studied different recipes to correct single-beam observations of nearby galaxies of different sizes and inclinations for aperture effects. This was done by comparing single-beam and multiple-beam observations along the major axis, which were corrected for aperture effects using different empirical or analytical prescriptions, to integrated maps of several nearby galaxies, including edge-on systems observed by different surveys. The resulting recipe is an analytical function determined by assuming that late-type galaxies are 3D exponentially declining discs with a characteristic scale length r_CO_=0.2r_24.5_, where r_24.5_ is the optical, g- (or B-) band isophotal radius at the 24.5mag/arcsec^2^ (25mag/arcsec^2^), as well as a scale height z_CO_=1/100r_24.5_. Our new CO data are then combined with those available in the literature to produce the most updated catalogue of CO observations for the HRS, now including 225 out of the 322 galaxies of the complete sample. The 3D exponential disc integration is applied to all the galaxies of the sample to measure their total CO fluxes, which are later transformed into molecular gas masses using a constant and a luminosity-dependent X_CO_ conversion factor. We also collect HI data for 315 HRS galaxies from the literature and present it in a homogenised form.
- ID:
- ivo://CDS.VizieR/J/A+A/496/45
- Title:
- CO maps of three lensed submillimetre galaxies
- Short Name:
- J/A+A/496/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Submillimetre galaxies (SMGs) are distant, dusty galaxies undergoing star formation at prodigious rates. Recently there has been major progress in understanding the nature of the bright SMGs (i.e. S_850um_>5mJy). The samples for the fainter SMGs are small and are currently in a phase of being built up through identification studies. We study the molecular gas content in the two SMGs, SMMJ163555 and SMMJ163541, at redshifts z=1.034 and z=3.187 with unlensed submillimetre fluxes of 0.4mJy and 6.0mJy. Both SMGs are gravitationally lensed by the foreground cluster Abell 2218. We used the IRAM Plateau de Bure Interferometer to obtain observations at 3mm of the lines CO(2-1) for SMMJ163555 and CO(3-2) for SMMJ163541. Additionally, we obtained CO(4-3) observations for the candidate z=4.048 SMMJ163556 with an unlensed submillimetre flux of 2.7mJy. Results: The CO(2-1) line was detected for SMMJ163555 at redshift 1.0313 with an integrated line intensity of 1.2+/-0.2Jy.km/s and a line width of 410+/-120km/s. From this a gas mass of 1.6x10^9^M_{sun}_ is derived and a star formation efficiency of 440L_{sun}_/M_{sun}_ estimated. The CO(3-2) line was detected for SMMJ163541 at redshift 3.1824, possibly with a second component at redshift 3.1883, with an integrated line intensity of 1.0+/-0.1Jy.km/s and a line width of 280+/-50km/s. From this a gas mass of 2.2x10^10^M_{sun}_ is derived and a star formation efficiency of 1000L_{sun}_/M_{sun}_ is estimated. For SMMJ163556, the CO(4-3) is undetected within the redshift range 4.035-4.082 down to a sensitivity of 0.15Jy.km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A127
- Title:
- Comet C/2016 R2 (PanSTARRS) IRAM spectra
- Short Name:
- J/A+A/619/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23-24 January 2018 with the IRAM 30m telescope, and in January to March 2018 with the Nancay radio telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH_3_OH, H_2_CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N_2_ ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.
- ID:
- ivo://CDS.VizieR/J/PASJ/60/1297
- Title:
- CO molecular clouds in Carina flare supershell
- Short Name:
- J/PASJ/60/1297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of ^12^CO(J=1-0) and ^13^CO(J=1-0) molecular clouds in the spatio-velocity range of the Carina Flare supershell, GSH287+04-17. The data cover a region of ~66 square degrees and were taken with the NANTEN 4m telescope, at spatial and velocity resolutions of ~2.6' and 0.1km/s. Decomposition of the emission results in the identification of 156 ^12^CO clouds and 60 ^13^CO clouds, for which we provide observational and physical parameters.
- ID:
- ivo://CDS.VizieR/J/PASJ/53/1081
- Title:
- CO molecular clouds in Lupus
- Short Name:
- J/PASJ/53/1081
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lupus star-forming region has been surveyed for molecular clouds in ^12^CO with the NANTEN radio telescope, and a cloud mass of 1.7x10^4^M_{sun}_ has been revealed. We were able to detect 105 molecular clouds, most of which are relatively small and of low mass. The members of the Sco OB 2 association and the X-ray detected pre-main-sequence stars (PMSs) are distributed all around this region. The OB stars and the molecular clouds show exclusive distributions. Large fractions of the PMSs are located away from the molecular clouds, and are thus isolated. The origin of the isolated PMSs is discussed. About 40% of the PMSs have candidates of their parent clouds less massive than 20M_{sun}_ within 4pc, which suggests in-situ star formation in the small clouds and their rapid dissipation. The separations from the PMSs to the clouds are typically larger than those in the Chamaeleon region, probably because of coexisting OB stars. From the cloud structures and the distributions of the OB stars, PMSs, and H I expanding shell, it is suggested that the molecular clouds have been effectively dissipated by the OB stars and a shock wave, which may also have triggered star formation in Lupus and the {rho} Oph clouds.
