- ID:
- ivo://CDS.VizieR/J/A+A/556/L1
- Title:
- ALMA observations of 12CO/13CO around R Scl
- Short Name:
- J/A+A/556/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detached-shell source R Scl, displaying CO emission from recent mass loss, in a binary-induced spiral structure as well as in a clumpy shell produced during a thermal pulse, provides a unique laboratory for studying the differences in CO isotope abundances throughout its recent evolution. We observed both the ^12^CO(J=3-2) and the ^13^CO(J=3-2) line using ALMA. We find significant variations in the ^12^CO/^13^CO intensity ratios and consequently in the abundance ratios. The average CO isotope abundance ratio is at least a factor three lower in the shell (~19) than that in the present-day (<~300yr) mass loss (>60). Additionally, variations in the ratio of more than an order of magnitude are found in the shell itself. We attribute these variations to the competition between selective dissociation and isotope fractionation in the shell, of which large parts cannot be warmer than ~35K. However, we also find that the ^12^CO/^13^CO ratio in the present-day mass loss is significantly higher than the ^12^C/^13^C ratio determined in the stellar photosphere from molecular tracers (~19). The origin of this discrepancy is still unclear, but we speculate that it is due to an embedded source of UV-radiation that is primarily photo-dissociating ^13^CO. This radiation source could be the hitherto hidden companion. Alternatively, the UV-radiation could originate from an active chromosphere of R Scl itself. Our results indicate that caution should be taken when directly relating the ^12^CO/^13^CO intensity and ^12^C/^13^C abundance ratios for specific asymptotic giant branch stars, in particular binaries or stars that display signs of chromospheric stellar activity.
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- ID:
- ivo://CDS.VizieR/J/ApJ/903/145
- Title:
- ALMaQUEST. IV. ALMA-MaNGA QUEnching & star formation
- Short Name:
- J/ApJ/903/145
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- The ALMaQUEST (ALMA-MaNGA QUEnching and STar formation) survey is a program with spatially resolved 12CO(1-0) measurements obtained with the Atacama Large Millimeter Array (ALMA) for 46 galaxies selected from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) DR15 optical integral-field spectroscopic survey. The aim of the ALMaQUEST survey is to investigate the dependence of star formation activity on the cold molecular gas content at kiloparsec scales in nearby galaxies. The sample consists of galaxies spanning a wide range in specific star formation rate (sSFR), including starburst (SB), main-sequence (MS), and green valley (GV) galaxies. In this paper, we present the sample selection and characteristics of the ALMA observations and showcase some of the key results enabled by the combination of spatially matched stellar populations and gas measurements. Considering the global (aperture-matched) stellar mass, molecular gas mass, and star formation rate of the sample, we find that the sSFR depends on both the star formation efficiency (SFE) and the molecular gas fraction (f_H_2__), although the correlation with the latter is slightly weaker. Furthermore, the dependence of sSFR on the molecular gas content (SFE or f_H_2__) is stronger than that on either the atomic gas fraction or the molecular-to-atomic gas fraction, albeit with the small Hi sample size. On kiloparsec scales, the variations in both SFE and f_H_2__ within individual galaxies can be as large as 1-2dex, thereby demonstrating that the availability of spatially resolved observations is essential to understand the details of both star formation and quenching processes.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/23
- Title:
- Aminoacetonitrile transition frequencies
- Short Name:
- J/ApJS/209/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aminoacetonitrile, NH_2-CH_2_-CN, has been considered one of the important precursors of glycine, the simplest amino acid, and was identified in Sgr B2(N) by Belloche et al. (2008, Cat. J/A+A/482/179) based on their reanalysis of previous laboratory measurements. However, these laboratory measurements were limited to the 1mm wavelength region even for the normal species, and recent new radio telescopes like ALMA require rest frequencies in a higher frequency range. Therefore, we have extended the pure rotational spectra of aminoacetonitrile and its amino-hydrogen-deuterated isotopologues (NHDCH_2_CN and ND_2_CH_2_CN) up to 1.2THz and 0.6THz, respectively. Belloche et al. indicated that the normal species may have been misassigned in a previous microwave study by Bogey et al. (1990JMoSp.143..180B). We found that two more b-type spectral transitions were misassigned, and all b-type transition frequencies above K_a_=2 had to be remeasured. For isotopologues, spectra above 40 GHz were observed for the first time and higher order centrifugal distortion constants have been determined. The extension of the measurements helped improve the molecular constants. The errors in the frequency catalog data of normal and deuterated isotopologues are on the order of 100kHz up to 1.2THz and 0.6THz, respectively, which are precise enough for the future astronomical observations.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A39
- Title:
- A 3mm molecular line survey of NGC1068
- Short Name:
- J/A+A/549/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the molecular composition of the interstellar medium (ISM) surrounding an active galactic nucleus (AGN), by making an inventory of molecular species and their abundances, to establish a chemical differentiation between starburst galaxies and AGN. We used the IRAM-30m telescope to observe the central 1.5-2kpc region of NGC 1068, covering the frequencies between 86.2GHz and 115.6GHz. Using Boltzmann diagrams, we calculated the column densities of the detected molecules. We used a chemical model to reproduce the abundances found in the AGN, to determine the origin of each detected species, and to test the influence of UV fields, cosmic rays, and shocks on the ISM.
- ID:
- ivo://CDS.VizieR/J/ApJS/177/275
- Title:
- 1.3 and 2mm survey of IRC+10216
- Short Name:
- J/ApJS/177/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our spectral line surveys in the 1.3 and 2mm windows toward the carbon-rich envelope of IRC+10216. There were 377 lines detected in total, of which 360 lines are assigned to 57 known molecules (including 29 rare isotopomers and two cyclic isomers). Only 17 weak lines remain unidentified. Rotational lines of isotopomers ^13^CCH and HN^13^C are detected for the first time in IRC+10216 . The detection of the formaldehyde lines in this star is also confirmed. Possible abundance differences among the three ^13^C-substituted isotopic isomers of HC_3_N is reported. Isotopic ratios of C and O are confirmed to be nonsolar while those of S and Si to be nearly solar. Column densities have been estimated for 15 molecular species. Modified spectroscopic parameters have been calculated for NaCN, Na^13^CN, KCN, and SiC_2_. Transition frequencies from the present observations were used to improve the spectroscopic parameters of Si^13^CC, ^29^SiC_2_, and ^30^SiC_2_.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A30
- Title:
- APM 08279+5255 CO(4-3) spectrum
- Short Name:
- J/A+A/608/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a high sensitivity observation of the UFO/BAL quasar APM 08279+5255 at z=3.912 with NOEMA at 3.2mm, aimed at detecting fast moving molecular gas. We report the detection of blueshifted CO(4-3) with maximum velocity (v95%) of -1340km/s, with respect to the systemic peak emission, and a luminosity of L'=9.9x10^9^{mu}^-1^K.km/s/pc^2^, where {mu} is the lensing magnification factor. We discuss various scenarios for the nature of this emission and conclude that this is the first detection of fast molecular gas at redshift >3. We derived a mass flow rate of molecular gas in the range dM/dt=3-7.4x10^3^M_{sun}_/yr and momentum boost (dP_OF_/dt)/(dP_AGN_/dt)~2-6, which is therefore consistent with a momentum conserving flow. For the largest dP_OF_ the scaling is also consistent with an energy conserving flow with an efficiency of ~10-20%. The present data can hardly discriminate between the two expansion modes. The mass loading factor of the molecular outflow {eta}=(dM_OF_/dt)/SFR is >>1. We also detected a molecular emission line at a frequency of 94.83GHz corresponding to a rest-frame frequency of 465.8GHz; we tentatively identified this frequency with the cation molecule N_2_H^+^(5-4), which would be the first detection of this species at high redshift. We discuss the alternative possibility that this emission is due to a CO emission line from the, so far undetected, lens galaxy. Further observations of additional transitions of the same species with NOEMA can discriminate between the two scenarios.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A146
- Title:
- ATLASGAL cold high-mass clumps with NH_3_
- Short Name:
- J/A+A/544/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The APEX Telescope Large Area Survey: The Galaxy (ATLASGAL) is an unbiased continuum survey of the inner Galactic disk at 870 micron. It covers +/-60{deg} in Galactic longitude and aims to find all massive clumps at various stages of high-mass star formation in the inner Galaxy, particularly the earliest evolutionary phases. We aim to determine properties such as the gas kinetic temperature and dynamics of new massive cold clumps found by ATLASGAL. Most importantly, we derived their kinematical distances from the measured line velocities. We observed the ammonia (J,K)=(1,1) to (3,3) inversion transitions toward 862 clumps of a flux-limited sample of submm clumps detected by ATLASGAL and extracted ^13^CO(1-0) spectra from the Galactic Ring Survey (GRS). We determined distances for a subsample located at the tangential points (71 sources) and for 277 clumps whose near/far distance ambiguity is resolved. Most ATLASGAL clumps are cold with rotational temperatures from 10-30K with a median of 17K. They have a wide range of NH_3_ linewidths (1-7km/s with 1.9km/s as median, which by far exceeds the thermal linewidth, as well as a broad distribution of high column densities from 10^14^ to 10^16^cm^-2^ (median of 2x10^15^cm^-2^) with an NH_3_ abundance in the range of 5 to 30x10^-8^. ATLASGAL sources are massive, >100M_{sun}_, and a fraction of clumps with a broad linewidth is in virial equilibrium. We found an enhancement of clumps at Galactocentric radii of 4.5 and 6kpc. The comparison of the NH_3_ lines as high-density probes with the GRS ^13^CO emission as low-density envelope tracer yields broader linewidths for ^13^CO than for NH_3_. The small differences in derived clump velocities between NH_3_ (representing dense core material) and ^13^CO (representing more diffuse molecular cloud gas) suggests that the cores are essentially at rest relative to the surrounding giant molecular cloud. The high detection rate (87%) confirms ammonia as an excellent probe of the molecular content of the massive, cold clumps revealed by ATLASGAL. A clear trend of increasing rotational temperatures and linewidths with evolutionary stage is seen for source samples ranging from 24 micron dark clumps to clumps with embedded HII regions. The survey provides the largest ammonia sample of high-mass star forming clumps and thus presents an important repository for the characterization of statistical properties of the clumps and the selection of subsamples for detailed, high-resolution follow-up studies.
- ID:
- ivo://CDS.VizieR/J/AJ/154/152
- Title:
- CARMA 1 cm spectral line survey of Orion-KL
- Short Name:
- J/AJ/154/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orion-KL is a well-known high-mass star-forming region that has long been the target of spectral line surveys and searches for complex molecules. One spectral window where the region had never been surveyed is around wavelengths of {lambda}=1 cm. This is an important window to observe, due to the fundamental and low energy transitions of numerous complex molecules that indicate the maximum spatial extent of the molecular species; knowing the spatial distribution of a molecule aids in determining the formation mechanism(s) of that molecule. Additionally, there are fewer transitions in this window, reducing confusion caused by blended lines that can be very problematic at shorter wavelengths ({lambda}<3 mm). In this work, we present the first spectral line survey at {lambda}=1 cm of the Orion-KL region. A total of 89 transitions were detected from 14 molecular species and isotopologues, and two atomic species. The observations were conducted with the Combined Array for Research in Millimeter-wave Astronomy in both interferometric and single dish modes.
- ID:
- ivo://CDS.VizieR/J/A+A/566/L5
- Title:
- C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy) spectra
- Short Name:
- J/A+A/566/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectral survey in the 1mm wavelength range was undertaken in the long-period comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy) using the 30m telescope of the Institut de radioastronomie millimetrique (IRAM) in April and November-December 2013. We report the detection of ethylene glycol (CH_2OH)_2 (aGg' conformer) and formamide (NH_2CHO) in the two comets. The abundances relative to water of ethylene glycol and formamide are 0.2-0.3% and 0.02% in the two comets, similar to the values measured in comet C/1995 O1 (Hale-Bopp). We also report the detection of HCOOH and CH_3_CHO in comet C/2013 R1 (Lovejoy), and a search for other complex species (methyl formate, glycolaldehyde).
- ID:
- ivo://CDS.VizieR/J/A+A/589/A78
- Title:
- C/2012 F6 (Lemmon) and C/2013 R1 spectra (Lovejoy)
- Short Name:
- J/A+A/589/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The apparition of bright comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy) in March-April 2013 and January 2015, combined with the improved observational capabilities of submillimeter facilities, offered an opportunity to carry out sensitive compositional and isotopic studies of the volatiles in their coma. We observed comet Lovejoy with the IRAM 30m telescope between 13 and 26 January 2015, and with the Odin submillimeter space observatory on 29 January - 3 February 2015. We detected 22 molecules and several isotopologues. The H216O and H218O production rates measured with Odin follow a periodic pattern with a period of 0.94 days and an amplitude of ~25%. The inferred isotope ratios in comet Lovejoy are ^16^O/^18^O=499+/-24 and D/H=1.4+/-0.4*10^-4^ in water, ^32^S/^34^S=24.7+/-3.5 in CS, all compatible with terrestrial values. The ratio ^12^C/^13^C=109+/-14 in HCN is marginally higher than terrestrial and ^14^N/^15^N=145+/-12 in HCN is half the Earth ratio. Several upper limits for D/H or ^12^C/^13^C in other molecules are reported. From our observation of HDO in comet C/2014 Q2 (Lovejoy), we report the first D/H ratio in an Oort Cloud comet that is not larger than the terrestrial value. On the other hand, the observation of the same HDO line in the other Oort-cloud comet, C/2012 F6 (Lemmon), suggests a D/H value four times higher. Given the previous measurements of D/H in cometary water, this illustrates that a diversity in the D/H ratio and in the chemical composition, is present even within the same dynamical group of comets, suggesting that current dynamical groups contain comets formed at very different places or times in the early solar system.
