- 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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- ID:
- ivo://CDS.VizieR/J/A+A/648/A49
- Title:
- Comet 46P/Wirtanen millimetre-wave spectra
- Short Name:
- J/A+A/648/A49
- Date:
- 08 Feb 2022
- Publisher:
- CDS
- Description:
- We present the results of a molecular survey of comet 46P/Wirtanen undertaken with the IRAM 30-m and NOEMA radio telescopes in December 2018. Observations at IRAM 30-m during the 12-18 Dec. period comprise a 2mm spectral survey, which covers 25GHz, and a 1mm survey which covers 62GHz. The gas outflow velocity and kinetic temperature have been accurately constrained by the observations. We derive abundances of 11 molecules, some being identified remotely for the first time in a Jupiter-family comet, including complex organic molecules such as formamide, ethylene glycol, acetaldehyde or ethanol. Sensitive upper limits on the abundances of 24 other molecules are obtained. The comet is found to be relatively rich in methanol (3.4% relative to water) but relatively depleted in CO, CS, HNC, HNCO or HCOOH.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A71
- Title:
- CO spectra of 55 LIRGs and ULIRGs
- Short Name:
- J/A+A/628/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present IRAM-30m Telescope ^12^CO and ^13^CO observations of a sample of 55 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in the local universe. This sample is a subset of the Great Observatory All-Sky LIRG Survey (GOALS), for which we use ancillary multi-wavelength data to better understand their interstellar medium and star formation properties. Fifty-three (96%) of the galaxies are detected in ^12^CO, and 29 (52%) are also detected in ^13^CO above a 3{sigma} level. The median full width at zero intensity (FWZI) velocity of the CO line emission is 661km/s, and 54% of the galaxies show a multi-peak CO profile. Herschel photometric data is used to construct the far-IR spectral energy distribution of each galaxy, which are fit with a modified blackbody model that allows us to derive dust temperatures and masses, and infrared luminosities. We make the assumption that the gas-to-dust mass ratio of (U)LIRGs is comparable to local spiral galaxies with a similar stellar mass (i.e., gas/dust of mergers is comparable to their progenitors) to derive a CO-to-H_2_ conversion factor of <{alpha}>=1.8^+1.3^_0.8_M_{sun}_/(K.km/s/pc^2^); such a value is comparable to that derived for (U)LIRGs based on dynamical mass arguments. We derive gas depletion times of 400-600Myr for the (U)LIRGs, compared to the 1.3Gyr for local spiral galaxies. Finally, we re-examine the relationship between the ^12^CO/^13^CO ratio and dust temperature, confirming a transition to elevated ratios in warmer systems.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A94
- Title:
- CO spectra of 49 semi-regular variables
- Short Name:
- J/A+A/629/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to study the main properties of a volume-limited unbiased sample of well characterized semi-regular variables (SRs) in order to clarify important issues that need to be further explained, such as the formation of axially symmetric planetary nebulae (PNe) from spherical circumstellar envelopes (CSEs) that takes place during the mass loss process along the AGB phase. We present new high S/N IRAM 30m observations of the ^12^CO J=2-1, ^12^CO J=1-0, and ^13^CO J=1-0 lines, in a volume-limited sample of SRs for which the Hipparcos distances are between 100-500 pc and declinations above -25{deg}. We analyzed the data by characterizing the main properties of the CSEs. The ^12^CO J=2-1 data have been used to study the profiles, while the ^12^CO J=1-0 data have been used to estimate mass-loss rates for the complete sample. Moreover, the ^12^CO J=2-1 line has been used to determine the possible structures responsible for such profiles. We have classified the sources into four groups according to the different profiles and final gas expansion velocities. Type 1 and 2 profiles are broad and narrow symmetric lines, respectively. Type 1 profiles, furthermore, are more related to standard spherically symmetric envelopes already studied. Type 3 profiles, on the contrary, are strange profiles with very pronounced asymmetries. Type 4 profiles, finally, are those which show two different components: a narrow line profile superimposed on a broad pedestal component. We find that for sources which show this kind of profile, with two different components, the variation amplitude is very low, what means that these SRs do not have a well developed inner envelope differentiated from the outer one. Interestingly, we report a moderate correlation between mass-loss rates and ^12^CO J=1-0/^12^CO J=2-1 line intensity ratios for O-rich SRs, suggesting a different behaviour between C- and O-rich SRs. By using SHAPE+shapemol, we find a unified simple model based on an oblate spheroid, placed in different orientations, that may explain all the ^12^CO profiles in the sample, indicating that the gas expansion is, in general, predominantly equatorial. Moreover, in order to explain the type 4 profiles, we define an extra component which may somehow be a biconical structure or similar according to the structures already found in this kind of sources. Type 1 and 2 profiles, curiously, may also be explained by standard spherically symmetric envelopes, but often requiring anomalously low velocities. Type 3 and 4 profiles, however, need axial symmetry to be explained. We conclude that most circumstellar shells around SRs show axial, strongly non-spherical symmetry. More interferometric observations are needed in order to make firm conclusions about mass-loss processes and possible morphologies of SRs.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/98
- Title:
- DISCS. II. Southern sky disk data
- Short Name:
- J/ApJ/734/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers based on data from DISCS, a Submillimeter Array observing program aimed at spatially and spectrally resolving the chemical composition of 12 protoplanetary disks. We present data on six Southern sky sources -IM Lup, SAO 206462 (HD 135344b), HD 142527, AS 209, AS 205, and V4046 Sgr- which complement the six sources in the Taurus star-forming region reported previously. CO 2-1 and HCO^+^ 3-2 emission are detected and resolved in all disks and show velocity patterns consistent with Keplerian rotation. Where detected, the emission from DCO^+^ 3-2, N_2_H^+^ 3-2, H_2_CO 3_0 3_-2_0 2_ and 4_1 4_-3_1 3_, HCN 3-2, and CN 2_3 3/4/2_-1_2 2/3/1_ are also generally spatially resolved. The detection rates are highest toward the M and K stars, while the F star SAO 206462 has only weak CN and HCN emission, and H2CO alone is detected toward HD 142527.
- ID:
- ivo://CDS.VizieR/J/AJ/138/1380
- Title:
- Dust clumps in the Galactic Plane
- Short Name:
- J/AJ/138/1380
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present imaging observations of continuum emission from interstellar dust at 850 and 1200um of a section of the Galactic Plane covering 2deg^2^ centered at l=44{deg}. Complementary jiggle-mapping and fast-scanning techniques were used, respectively, at these two wavelengths. The mapped area includes the well-known star formation regions W49 and G45.1/45.5. Using an automated clump-finding routine, we identify 132 compact 850um emission features within the region above a completeness level of about 200mJy/beam. The positions of the latter objects were used to determine fluxes from the 1200um image. Spectral line data were subsequently obtained with the same observing beamwidth as at 850um for almost half of the objects; these were either imaged in the ^13^CO (3-2) line, or basic characteristics determined using the ^12^CO (3-2) transition. We use these data, supplemented by existing ^13^CO (1-0) and HI survey data, to determine distances and hence derive masses for the dust clump ensemble, assuming a uniform dust temperature of 15K. From these data we find that the number-mass relationship for clumps in the field is similar to that found for individual star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/607/A39
- Title:
- 7 FU Orionis-type stars CO spectral cubes
- Short Name:
- J/A+A/607/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- FU Orionis-type objects are pre-main sequence, low-mass stars with large outbursts in visible light that last for several years or decades. They are thought to represent an evolutionary phase during the life of every young star when accretion from the circumstellar disk is enhanced during recurring time periods. These outbursts are able to rapidly build up the star while affecting the physical conditions inside the circumstellar disk and thus the ongoing or future planet formation. In many models, infall from a circumstellar envelope seems to be necessary to trigger the outbursts. We characterise the morphology and the physical parameters of the circumstellar material around FU Orionis-type stars using the emission of millimetre-wavelength molecular tracers. The high-spatial-resolution study provides insight into the evolutionary state of the objects, the distribution of parameters in the envelopes and the physical processes forming the environment of these stars. We observed the J=1-0 rotational transition of ^13^CO and C^18^O towards eight northern FU Orionis-type stars (V1057 Cyg, V1515 Cyg, V2492 Cyg, V2493 Cyg, V1735 Cyg, V733 Cep, RNO 1B and RNO 1C) and determine the spatial and velocity structure of the circumstellar gas on a scale of a few thousand AU. We derive temperatures and envelope masses and discuss the kinematics of the circumstellar material.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A135
- Title:
- Gas dynamics in Massive Dense Cores in Cygnus-X
- Short Name:
- J/A+A/527/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the kinematic properties of dense gas surrounding massive protostars in a sample of five Massive Dense Cores (MDCs) in Cygnus-X. The aim is to investigate whether turbulent support plays a major role in stabilizing the cores against a rapid fragmentation into Jeans-mass objects. Alternatively the observed kinematics could indicate a high level of dynamics suggesting that the cores are actually not in equilibrium and dynamical processes could be the main driver to build up the final stellar masses.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A14
- Title:
- GaussPy+ decomposition of Galactic Ring Survey
- Short Name:
- J/A+A/633/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics on Galactic scales and, in particular, its link with the formation and evolution of dense structures in the interstellar medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines contained in these enormous data sets. In this work, we present an overview and the first results of a Gaussian decomposition of the entire Galactic Ring Survey (GRS) ^13^CO (1-0) data that consists of about 2.3 million spectra. We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussian components to the GRS spectra. These decomposition results enable novel and unexplored ways to interpret and study the gas velocity structure. We discuss the statistics of the fit components and relations between the fitted intensities, velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase towards the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also used our decomposition results to infer global properties of the gas emission and find that the number of fit components used per spectrum is indicative of the amount of structure along the line of sight. We find that the emission lines from regions located on the far side of the Galaxy show increased velocity dispersion values, which are likely due to beam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure by disentangling emission that belongs to the nearby Aquila Rift molecular cloud from emission that is more likely associated with the Perseus and Outer spiral arms. With this work, we also make our entire decomposition results available.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/160
- Title:
- 6.7GHz Class II methanol maser survey
- Short Name:
- J/ApJ/846/160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a systematic 6.7GHz Class II methanol maser survey using the Shanghai Tianma Radio Telescope toward targets selected from the all-sky Wide-Field Infrared Survey Explorer (WISE) point catalog. In this paper, we report the results from the survey of those at high Galactic latitudes, i.e., |b|>2{deg}. Of 1473 selected WISE point sources at high latitude, 17 point positions that were actually associated with 12 sources were detected with maser emission, reflecting the rarity (1%-2%) of methanol masers in the region away from the Galactic plane. Out of the 12 sources, 3 are detected for the first time. The spectral energy distribution at infrared bands shows that these new detected masers occur in the massive star-forming regions. Compared to previous detections, the methanol maser changes significantly in both spectral profiles and flux densities. The infrared WISE images show that almost all of these masers are located in the positions of the bright WISE point sources. Compared to the methanol masers at the Galactic plane, these high-latitude methanol masers provide good tracers for investigating the physics and kinematics around massive young stellar objects, because they are believed to be less affected by the surrounding cluster environment.
