- ID:
- ivo://CDS.VizieR/J/A+A/632/A19
- Title:
- IRAM intensity maps of 3 low-mass protostars
- Short Name:
- J/A+A/632/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methanol is a key species in astrochemistry since it is the most abundant organic molecule in the interstellar medium and is thought to be the mother molecule of many complex organic species. Estimating the deuteration of methanol around young protostars is of crucial importance because it highly depends on its formation mechanisms and the physical conditions during its moment of formation. We analyse several dozens of transitions from deuterated methanol isotopologues coming from various existing observational datasets obtained with the IRAM-PdBI and ALMA sub-mm interferometers to estimate the methanol deuteration surrounding three low-mass protostars on Solar System scales. A population diagram analysis allows us to derive a [CH_2_DOH]/[CH_3_OH] abundance ratio of 3-6% and a [CH_3_OD]/[CH_3_OH] ratio of 0.4-1.6% in the warm inner (<100-200AU) protostellar regions. These values are typically ten times lower than those derived with previous single-dish observations towards these sources but they are one to two orders of magnitude higher than the methanol deuteration measured in massive hot cores. Dust temperature maps obtained from Herschel and Planck observations show that massive hot cores are located in warmer molecular clouds than low-mass sources, with temperature differences of about 10K. The comparison of our measured values with the predictions of the gas-grain astrochemical model GRAINOBLE shows that such a temperature difference is sufficient to explain the different deuteration observed in low- to high-mass sources. This suggests that the physical conditions of the molecular cloud at the origin of the protostars mostly govern the present observed deuteration of methanol and, therefore, of more complex organic molecules. Finally, the methanol deuteration measured towards young solar-type protostars on Solar System scales seems to be higher by a factor of about 5 than the upper limit in methanol deuteration estimated in comet Hale-Bopp. If this result is confirmed by subsequent observations of other comets, this would imply that an important reprocessing of the organic material likely occurred in the solar nebula during the formation of the Solar System.
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Search Results
- ID:
- ivo://CDS.VizieR/VIII/66
- Title:
- IRAM observations in pre-star forming regions
- Short Name:
- VIII/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The goal of the IRAM key-project ``Small-scale structure of pre-star forming regions'' is to map three nearby (d~150pc), quiescent molecular clouds with a high angular and spectral resolution to study the molecular cloud structure down to the smallest linear scales currently accessible by single dish radio telescopes. The key-project maps are available as data cubes (velocity, right ascension or galactic longitude, declination or galactic latitude) available as a set of 40 FITS files stored in the fits subdirectory; a summary of these 40 files is contained in the file "list.dat". The observations reported concern the molecular clouds L1512, L134A, and MCLD 123.5+24.9 in the Polaris Flare. The released data set of the IRAM key-project (Falgarone et al., 1998A&A...331..669F) are error beam corrected using the beam pattern parameters published by Garcia-Burillo, Guelin and Cernicharo (1993A&A...274..123G) and observations made with the KOSMA 3m telescope. Bensch et al. (2001A&A...365..275B) present the corrected maps using the 30m beam pattern recently published by Greve et al. (1998A&AS..133..271G). They estimate the accuracy of the maps of the key-project as 10-15% for the CO(2-1), except for two ^13^CO(2-1) maps of the MCLD 123.5+24.9/Polaris Flare and of L1512 where the uncertainties are estimated to 22% and 18% respectively. For the CO(1-0) data, the overall accuracy is 11%.
- ID:
- ivo://CDS.VizieR/J/A+A/507/241
- Title:
- IR and 610MHz observations in MGRO J2019+37
- Short Name:
- J/A+A/507/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MGROJ2019+37 is an unidentified extended source of very high energy gamma-rays originally reported by the Milagro Collaboration as the brightest TeV source in the Cygnus region. Its extended emission could be powered by either a single or several sources. The GeV pulsar AGL J2020.5+3653 discovered by AGILE and associated with PSR J2021+3651 could contribute to the emission from MGRO J2019+37. The aim of this paper is to identify radio and near-infrared sources in the field of the extended TeV source MGRO J2019+37, and study potential counterparts to explain its emission. We surveyed a region of about 6 square degrees with the Giant Metrewave Radio Telescope (GMRT) at the frequency 610MHz. We also observed the central square degree of this survey in the near-infrared Ks-band using the 3.5m telescope in Calar Alto. Archival X-ray observations of some specific fields are included. VLBI observations of an interesting radio source were performed. We explored possible scenarios to produce the multi-TeV emission from MGRO J2019+37 and studied which of the sources could be the main particle accelerator.
- ID:
- ivo://CDS.VizieR/J/A+A/544/L7
- Title:
- IRAS 16293-2422 ALMA maps
- Short Name:
- J/A+A/544/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We focus on the kinematical properties of a proto-binary to study the infall and rotation of gas toward its two protostellar components. We present ALMA Science Verification observations with high-spectral resolution of IRAS 16293-2422 at 220.2GHz. The wealth of molecular lines in this source and the very high spectral resolution offered by ALMA allow us to study the gas kinematics with unprecedented detail.
- ID:
- ivo://CDS.VizieR/J/A+A/642/L7
- Title:
- IRAS 04302+2247 CO, CS, CN, H2CO, CH3OH maps
- Short Name:
- J/A+A/642/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical composition of planets is inherited from that of the natal protoplanetary disk at the time of planet formation. Increasing observational evidence suggests that planet formation occurs in less than 1-2Myr. This motivates the need for spatially resolved spectral observations of young Class I disks, as carried out by the ALMA chemical survey of Disk-Outflow sources in Taurus (ALMA-DOT). In the context of ALMA-DOT, we observe the edge-on disk around the Class I source IRAS 04302+2247 (the butterfly star) in the 1.3mm continuum and five molecular lines. We report the first tentative detection of methanol (CH_3_OH) in a Class I disk and resolve, for the first time, the vertical structure of a disk with multiple molecular tracers. The bulk of the emission in the CO 2-1, CS 5-4, and o-H_2_CO 3_1,2_-2_1,1_ lines originates from the warm molecular layer, with the line intensity peaking at increasing disk heights, z, for increasing radial distances, r. Molecular emission is vertically stratified, with CO observed at larger disk heights (aperture z/r~0.41-0.45) compared to both CS and H2CO, which are nearly cospatial (z/r~0.21-0.28). In the outer midplane, the line emission decreases due to molecular freeze-out onto dust grains (freeze-out layer) by a factor of >100 (CO) and 15 (CS). The H_2_CO emission decreases by a factor of only about 2, which is possibly due to H2CO formation on icy grains, followed by a nonthermal release into the gas phase. The inferred [CH_3_OH]/[H_2_CO] abundance ratio is 0.5-0.6, which is 1-2 orders of magnitude lower than for Class 0 hot corinos, and a factor ~2.5 lower than the only other value inferred for a protoplanetary disk (in TW Hya, 1.3-1.7). Additionally, it is at the lower edge but still consistent with the values in comets. This may indicate that some chemical reprocessing occurs in disks before the formation of planets and comets.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A47
- Title:
- IRAS F08572+3915 CO(1-0) datacube
- Short Name:
- J/A+A/635/A47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the role that AGN feedback plays in galaxy evolution we need in-depth studies of the multi-phase structure and energetics of galaxy-wide outflows. In this work we present new, deep (~50hr) NOEMA CO(1-0) line observations of the molecular gas in the powerful outflow driven by the AGN in the ultra-luminous infrared galaxy IRAS F08572+3915. We spatially resolve the outflow, finding that its most likely configuration is a wide-angle bicone aligned with the kinematic major axis of the rotation disk. The molecular gas in the wind reaches velocities up to approximately +/-1200km/s and transports nearly 20% of the molecular gas mass in the system. We detect a second outflow component located 6 kpc north-west from the galaxy moving away at 900km/s, which could be the result of a previous episode of AGN activity. The total mass and energetics of the outflow, which includes contributions from the ionized, neutral, warm and cold molecular gas phases is strongly dominated by the cold molecular gas. In fact, the molecular mass outflow rate is higher than the star formation rate, even if we only consider the gas in the outflow that is fast enough to escape the galaxy, which accounts for about 40% of the total mass of the outflow. This results in an outflow depletion time for the molecular gas in the central ~1.5kpc region of only ~3Myr, a factor of ~2 shorter than the depletion time by star formation activity.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/363
- Title:
- IRAS flux densities of S stars
- Short Name:
- J/A+AS/129/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is the purpose of this paper to rediscuss the circumstellar properties of S stars and to put these properties in perspective with our current understanding of the evolutionary status of S stars, in particular the intrinsic/extrinsic dichotomy. This dichotomy states that only Tc-rich ("intrinsic") S stars are genuine thermally-pulsing asymptotic giant branch stars, possibly involved in the M-S-C evolutionary sequence. Tc-poor S stars are referred to as "extrinsic" S stars, because they are the cooler analogs of barium stars, and like them, owe their chemical peculiarities to mass transfer across their binary system. Accordingly, an extensive data set probing the circumstellar environment of S stars (IRAS flux densities, maser emission, CO rotational lines) has been collected and critically evaluated. This data set combines new observations (9 stars have been observed in the CO J=2-1 line and 3 in the CO J=3-2 line, with four new detections) with existing material (all CO and maser observations of S stars published in the literature). The IRAS flux densities of S stars have been re-evaluated by co-adding the individual scans, in order to better handle the intrinsic variability of these stars in the IRAS bands, and possible contamination by Galactic cirrus.
- ID:
- ivo://CDS.VizieR/J/MNRAS/276/57
- Title:
- IRAS Galactic star-forming regions. II.
- Short Name:
- J/MNRAS/276/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the analysis of the occurrence of 22.2-GHz H_2_O maser emission in a sample of 1409 IRAS sources north of declination -30deg associated with star-forming regions are presented. Our sample contains all the IRAS sources that satisfy Emerson criteria for selecting molecular cores associated with the earliest evolutionary stages of the star-forming process. In a previous paper (Paper I, 1994MNRAS.266..123P), we have reported the results of the observations of about one third of the sample. In the present paper the observations of the remaining IRAS sources are presented: 18 of them are newly detected maser sources. The results show that 20 per cent of all IRAS sources that satisfy the Wood & Churchwell criteria have H2O water masers. This is in agreement with the assumption that these criteria select objects that are connected with the early phases of the evolution of high-mass star-forming regions. Moreover, about one third of the whole sample selected according to Emerson criteria contains IRAS sources that are not associated with massive star-forming processes, but probably with molecular cores in low-mass star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/299/347
- Title:
- IRAS galaxies behind Taurus clouds
- Short Name:
- J/A+A/299/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a complete search for IRAS galaxies in the Taurus molecular cloud region at l=169deg to 177deg and b=-19deg to -12deg. We selected a total number of 36 galaxies and galaxy candidates and looked for the 21-cm H I line in 25 objects; we detected H I emission in five of them including one with previously unknown redshift. The spatial density of IRAS galaxies with cz=4000 to 6000km/s is lower in this region than in the adjacent regions at both sides along galactic longitude, where the Perseus supercluster and the Gemini-Monoceros filament are respectively located.
- ID:
- ivo://CDS.VizieR/J/A+A/499/233
- Title:
- IRAS 05345+3157 mm high-angular resolution maps
- Short Name:
- J/A+A/499/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To better understand the initial conditions of the high-mass star formation process, it is crucial to study at high-angular resolution the morphology, the kinematics, and eventually the interactions of the coldest condensations associated with intermediate-/high-mass star forming regions. The paper studies the cold condensations in the intermediate-/high-mass proto-cluster IRAS 05345+3157, focusing the attention on the interaction with the other objects in the cluster. We have performed millimeter high-angular resolution observations, both in the continuum and several molecular lines, with the PdBI and the SMA. The millimeter maps reveal the presence of 3 cores inside the interferometers primary beam, called C1-a, C1-b and C2. The lines, specifically N2H+ and N2D+, indicate the presence of two potential pre-stellar condensations (called N and S) not associated with the continuum sources. C1-b is very likely associated with a newly formed early-B ZAMS star embedded inside a hot-core, while C1-a is more likely associated with a class 0 intermediate-mass protostar. The nature of C2 is unclear. Both C1-a and C1-b are good candidates as driving sources of a powerful CO outflow, strongly interacting with both N and S, as demonstrated by the velocity gradient across both condensations. Our major conclusion is that the chemical properties of these pre-stellar cores are similar to those observed in low-mass isolated ones, while the kinematics is dominated by the turbulence triggered by the CO outflow, which can influence their evolution.
