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681. ALMA data cubes for HD 101584
ID:
ivo://CDS.VizieR/J/A+A/623/A153
Title:
ALMA data cubes for HD 101584
Short Name:
J/A+A/623/A153
Date:
21 Oct 2021
Publisher:
CDS
Description:
There is growing evidence that red giant evolution is often affected by an interplay with a nearby companion, in some cases taking the form of a common-envelope evolution. We have performed a study of the characteristics of the circumstellar environment of the binary object HD ,101584, that provides information on a likely evolutionary scenario. We have obtained and analyzed ALMA observations, complemented with observations using APEX, of a large number of molecular lines. An analysis of the spectral energy distribution has also been performed. Emissions from 12 molecular species (not counting isotopologues) have been observed, and most of them mapped with angular resolutions in the range 0.1" to 0.6". Four circumstellar components are identified: i) a central compact source of size ~=0.15", ii) an expanding equatorial density enhancement (a flattened density distribution in the plane of the orbit) of size ~=3", iii) a bipolar high-velocity outflow (~=150km/s), and iv) an hourglass structure. The outflow is directed almost along the line of sight. There is evidence of a second bipolar outflow. The mass of the circumstellar gas is ~=0.5[D/1kpc]^2^M_{sun}_, about half of it lies in the equatorial density enhancement. The dust mass is ~=0.01[D/1kpc]^2^M_{sun}_, and a substantial fraction of this is in the form of large-sized, up to 1mm, grains. The estimated kinetic age of the outflow is ~=770[D/1kpc]yr. The kinetic energy and the scalar momentum of the accelerated gas are estimated to be 7x10^45^[D/1kpc]^2^erg and 10^39^[D/1kpc]^2^g.cm/s, respectively. We provide good evidence that the binary system HD 101584 is in a post-common-envelope-evolution phase, that ended before a stellar merger. Isotope ratios combined with stellar mass estimates suggest that the primary star's evolution was terminated already on the first red giant branch (RGB). Most of the energy required to drive the outflowing gas was probably released when material fell towards the companion.
682. ALMA data cubes for IRC+10216
ID:
ivo://CDS.VizieR/J/A+A/629/A146
Title:
ALMA data cubes for IRC+10216
Short Name:
J/A+A/629/A146
Date:
21 Oct 2021
Publisher:
CDS
Description:
Low-mass evolved stars are major contributors to interstellar medium enrichment as a consequence of the intense mass-loss process these stars experience at the end of their lives. The study of the gas in the envelopes surrounding asymptotic giant branch (AGB)stars through observations in the millimetre wavelength range provides information about the history and nature of these molecular factories. Here we present ALMA observations at subarsecond resolution, complemented with IRAM-30m data, of several lines of SiO, SiS, and CS towards the best-studied AGB circumstellar envelope, IRC+10 216. We aim to characterise their spatial distribution and determine their fractional abundances mainly through radiative transfer and chemical modelling. The three species display extended emission with several enhanced emission shells. CS displays the most extended distribution reaching distances up to ap-proximately 20". SiS and SiO emission have similar sizes of approximately 11", but SiS emission is slightly more compact. We have estimated fractional abundances relative to H_2_, which on average are equal to f(SiO)~10^-7^, f(SiS)~10^-6^, and f(CS)~10^-^6 up to the photo-dissociation region. The observations and analysis presented here show evidence that the circumstellar material displays clear deviations from an homogeneous spherical wind, with clumps and low density shells that may allow UV photons from the interstellar medium (ISM) to penetrate deep into the envelope, shifting the photo-dissociation radius inwards. Our chemical model predicts photo-dissociation radii compatible with those derived from the observations, although it is unable to predict abundance variations from the starting radius of the calculations (~10R_{sun}_), which may reflect the simplicity of the model. We conclude that the spatial distribution of the gas proves the episodic and variable nature of the mass loss mechanism of IRC+10 216, on timescales of hundreds of years
683. ALMA datacubes of 6 nearby galaxies
ID:
ivo://CDS.VizieR/J/A+A/641/A24
Title:
ALMA datacubes of 6 nearby galaxies
Short Name:
J/A+A/641/A24
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigated the influence of the random velocity of molecular gas on star-formation activities of 6 nearby galaxies. The physical properties of a molecular cloud, such as temperature and density, influence star-formation activities in the cloud. Additionally, local and turbulent motions of molecules in a cloud may exert substantial pressure against gravitational collapse and thus prevent or reduce star formation in the cloud. However, the influence of gas motion on star-formation activities remains poorly understood. We used data from the Atacama Large Millimeter/submillimeter Array to obtain ^12^CO(J=1-0) flux and velocity dispersion. We then combined these data with 3.6 and 8 micron midinfrared data from the Spitzer Space Telescope to evaluate the effects of gas motion on star-formation activities in several nearby galaxies. We discovered that relatively high velocity dispersion in molecular clouds corresponded with relatively low star-formation activity. Considering the velocity dispersion as an additional parameter, we derived a modified Kennicutt-Schmidt law with a gas surface density power index 0.84 and velocity dispersion power index -0.61.
684. ALMA data for 5 luminous & ultraluminous IR gal.
ID:
ivo://CDS.VizieR/J/ApJ/882/5
Title:
ALMA data for 5 luminous & ultraluminous IR gal.
Short Name:
J/ApJ/882/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new analysis of high-resolution data from the Atacama Large Millimeter/submillimeter Array for five luminous or ultraluminous infrared galaxies gives a slope for the Kennicutt-Schmidt (KS) relation equal to 1.74_-0.07_^+0.09^ for gas surface densities {Sigma}_mol_>10^3^M_{sun}_/pc^2^ and an assumed constant CO-to-H2 conversion factor. The velocity dispersion of the CO line, {sigma}_v_, scales approximately as the inverse square root of {Sigma}_mol_, making the empirical gas scale height determined from H~0.5{sigma}^2^/({pi}G{Sigma}_mol_) nearly constant, 150-190pc, over 1.5 orders of magnitude in {Sigma}_mol_. This constancy of H implies that the average midplane density, which is presumably dominated by CO-emitting gas for these extreme star-forming galaxies, scales linearly with the gas surface density, which in turn implies that the gas dynamical rate (the inverse of the freefall time) varies with {Sigma}_mol_^1/2^, thereby explaining most of the super-linear slope in the KS relation. Consistent with these relations, we also find that the mean efficiency of star formation per freefall time is roughly constant, 5%-7%, and the gas depletion time decreases at high {Sigma}_mol_, reaching only ~16Myr at {Sigma}_mol_~10^4^M_{sun}_/pc^2^. The variation of {sigma}_v_ with {Sigma}_mol_ and the constancy of H are in tension with some feedback-driven models, which predict {sigma}_v_ to be more constant and H to be more variable. However, these results are consistent with simulations in which large-scale gravity drives turbulence through a feedback process that maintains an approximately constant Toomre Q instability parameter.
685. ALMA FITS cubes of CO(1-0) and CO(2-1)
ID:
ivo://CDS.VizieR/J/A+A/605/A116
Title:
ALMA FITS cubes of CO(1-0) and CO(2-1)
Short Name:
J/A+A/605/A116
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our goal is to characterize the intermediate age, detached shell carbon star U Antliae morphologically and physically in order to study the mass-loss evolution after a possible thermal pulse. High spatial resolution ALMA observations of unprecedented quality in thermal CO lines allow us to derive first critical spatial and temporal scales and constrain modeling effects to estimate mass-loss rates for both the present day as well as the ejection period of the detached shell. The detached shell is remarkably thin, overall spherically symmetric, and shows a barely resolved filamentary substructure possibly caused by instabilities in the interaction zone of winds with different outflow velocities. The expansion age of the detached shell is of the order of 2700 years and its overall width indicates a high expansion-velocity and high mass-loss period of only a few hundred years at an average mass-loss rate of ~10^-5^M_{sun}_/yr. The post-high-mass-loss-rate-epoch evolution of U Ant shows a significant decline to a substantially lower gas expansion velocity and a mass-loss rate amounting to 4x10^-8^M_{sun}_/yr, at present being consistent with evolutionary changes as predicted for the period between thermal pulses.
686. ALMA Frontier Fields Survey. I.
ID:
ivo://CDS.VizieR/J/A+A/597/A41
Title:
ALMA Frontier Fields Survey. I.
Short Name:
J/A+A/597/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dusty star-forming galaxies are among the most prodigious systems at high redshift (z>1), characterized by high star-formation rates and huge dust reservoirs. The bright end of this population has been well characterized in recent years, but considerable uncertainties remain for fainter dusty star-forming galaxies, which are responsible for the bulk of star formation at high redshift and thus play a key role in galaxy growth and evolution. In this first paper of our series, we describe our methods for finding high redshift faint dusty galaxies using millimeter observations with ALMA. We obtained ALMA 1.1mm mosaic images for three strong-lensing galaxy clusters from the Frontier Fields Survey, which constitute some of the best studied gravitational lenses to date. The ~2'x2' mosaics overlap with the deep HST WFC3/IR footprints and encompass the high magnification regions of each cluster for maximum intrinsic source sensitivity. The combination of extremely high ALMA sensitivity and the magnification power of these clusters allows us to systematically probe the sub-mJy population of dusty star-forming galaxies over a large surveyed area. We present a description of the reduction and analysis of the ALMA continuum observations for the galaxy clusters Abell 2744 (z=0.308), MACS J0416.1-2403 (z=0.396) and MACS J1149.5+2223 (z=0.543), for which we reach observed rms sensitivities of 55, 59 and 71uJy/beam respectively. We detect 12 dusty star-forming galaxies at S/N>=5.0 across the three clusters, all of them presenting coincidence with near-infrared detected counterparts in the HST images. None of the sources fall close to the lensing caustics, thus they are not strongly lensed. The observed 1.1mm flux densities for the total sample of galaxies range from 0.41 to 2.82mJy, with observed effective radii spanning <~0.05" to 0.37"+/-0.21". The lensing-corrected sizes of the detected sources appear to be in the same range as those measured in brighter samples, albeit with possibly larger dispersion.
687. ALMA Frontier Fields Survey. V.
ID:
ivo://CDS.VizieR/J/A+A/633/A160
Title:
ALMA Frontier Fields Survey. V.
Short Name:
J/A+A/633/A160
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Hubble Frontier Fields offer an exceptionally deep window into the high-redshift universe, covering a substantially larger area than the Hubble Ultra-Deep field at low magnification and probing 1-2mags deeper in exceptional high-magnification regions. This unique parameter space, coupled with the exceptional multi-wavelength ancillary data, can facilitate for useful insights into distant galaxy populations. We aim to leverage Atacama Large Millimetre Array (ALMA) band 6 (~263GHz) mosaics in the central portions of five Frontier Fields to characterize the infrared (IR) properties of 1582 ultraviolet (UV)-selected Lyman-Break Galaxies (LBGs) at redshifts of z~2-8. We investigated individual and stacked fluxes and IR excess (IRX) values of the LBG sample as functions of stellar mass (M_star), redshift, UV luminosity and slope {beta}, and lensing magnification. LBG samples were derived from color-selection and photometric redshift estimation with Hubble Space Telescope photometry. Spectral energy distributions (SED)-templates were fit to obtain luminosities, stellar masses, and star formation rates for the LBG candidates. We obtained individual IR flux and IRX estimates, as well as stacked averages, using both ALMA images and u-v visibilities. Two (2) LBG candidates were individually detected above a significance of 4.1-sigma, while stacked samples of the remaining LBG candidates yielded no significant detections. We investigated our detections and upper limits in the context of the IRX-M_star and IRX-{beta} relations, probing at least one dex lower in stellar mass than past studies have done. Our upper limits exclude substantial portions of parameter space and they are sufficiently deep in a handful of cases to create mild tension with the typically assumed attenuation and consensus relations. We observe a clear and smooth trend between M* and {beta}, which extends to low masses and blue (low) {beta} values, consistent with expectations from previous works.
688. ALMA galaxy properties in the COSMOS survey field
ID:
ivo://CDS.VizieR/J/ApJ/820/83
Title:
ALMA galaxy properties in the COSMOS survey field
Short Name:
J/ApJ/820/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
ALMA Cycle 2 observations of long-wavelength dust emission in 145 star-forming galaxies are used to probe the evolution of the star-forming interstellar medium (ISM). We also develop a physical basis and empirical calibration (with 72 low-z and z~2 galaxies) for using the dust continuum as a quantitative probe of ISM masses. The galaxies with the highest star formation rates (SFRs) at <z>=2.2 and 4.4 have gas masses up to 100 times that of the Milky Way and gas mass fractions reaching 50%-80%, i.e., gas masses 1-4x their stellar masses. We find a single high-z star formation law: SFR=35 M_mol_^0.89^x(1+z)_z=2_^0.95^x(sSFR)_MS_^0.23^ M_{sun}_/yr - an approximately linear dependence on the ISM mass and an increased star formation efficiency per unit gas mass at higher redshift. Galaxies above the main sequence (MS) have larger gas masses but are converting their ISM into stars on a timescale only slightly shorter than those on the MS; thus, these "starbursts" are largely the result of having greatly increased gas masses rather than an increased efficiency of converting gas to stars. At z>1, the entire population of star-forming galaxies has ~2-5 times shorter gas depletion times than low-z galaxies. These shorter depletion times indicate a different mode of star formation in the early universe - most likely dynamically driven by compressive, high-dispersion gas motions - a natural consequence of the high gas accretion rates.
689. ALMA 106GHz continuum observations in Chamaeleon I
ID:
ivo://CDS.VizieR/J/ApJ/823/160
Title:
ALMA 106GHz continuum observations in Chamaeleon I
Short Name:
J/ApJ/823/160
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an Atacama Large Millimeter/submillimeter Array (ALMA) 106 GHz (Band 3) continuum survey of the complete population of dense cores in the Chamaeleon I molecular cloud. We detect a total of 24 continuum sources in 19 different target fields. All previously known Class 0 and Class I protostars in Chamaeleon I are detected, whereas all of the 56 starless cores in our sample are undetected. We show that the Spitzer+Herschel census of protostars in Chamaeleon I is complete, with the rate at which protostellar cores have been misclassified as starless cores calculated as <1/56, or <2%. We use synthetic observations to show that starless cores collapsing following the turbulent fragmentation scenario are detectable by our ALMA observations when their central densities exceed ~10^8^/cm^3^, with the exact density dependent on the viewing geometry. Bonnor-Ebert spheres, on the other hand, remain undetected to central densities at least as high as 10^10^/cm^3^. Our starless core non-detections are used to infer that either the star-formation rate is declining in Chamaeleon I and most of the starless cores are not collapsing, matching the findings of previous studies, or that the evolution of starless cores are more accurately described by models that develop less substructure than predicted by the turbulent fragmentation scenario, such as Bonnor-Ebert spheres. We outline future work necessary to distinguish between these two possibilities.
690. ALMA images of HD 135344B
ID:
ivo://CDS.VizieR/J/A+A/619/A161
Title:
ALMA images of HD 135344B
Short Name:
J/A+A/619/A161
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spiral arms, rings and large scale asymmetries are structures observed in high resolution observations of protoplanetary disks, and it appears that some of the disks showing spiral arms in scattered light also show asymmetries in millimeter-sized dust. HD 135344B is one of these disks. Planets are invoked as the origin of these structures, but no planet has been observed so far and up per limits are becoming more stringent with time. We want to investigate the nature of the asymmetric structure in the HD 135344B disk in order to understand the origin of the spirals and of the asymmetry seen in this disk. Ultimately, we aim at understanding whether or not one or more planets are needed to explain such structures. We present new ALMA sub-0.1" resolution observations at optically thin wavelengths (lambda=2.8mm and 1.9mm) of the HD 135344B disk. The high spatial resolution allows us to unambiguously characterize the mm-dust morphology of the disk. The low optical depth of continuum emission probes the bulk of the dust content of the vortex. Moreover, we combine the new observations with archival data at shorter wavelengths to perform a multi-wavelength analysis and to obtain information about the dust distribution and properties inside the observed asymmetry. We resolve the asymmetric disk into a symmetric ring + asymmetric crescent, and observe that: (1) the spectral index strongly decreases at the center of the vortex, consistent with the presence of large grains; (2) for the first time, an azimuthal shift of the peak of the vortex with wavelength is observed; (3) the azimuthal width of the vortex decreases at longer wavelengths, as expected for dust traps. These features allow to confirm the nature of the asymmetry as a vortex. Finally, under the assumption of optically thin emission, a lower limit to the total mass of the vortex is 0.3M_Jupiter_. Considering the uncertainties involved in this estimate, it is possible that the actual mass of the vortex is higher and possibly within the required values (~4M_Jupiter_) to launch spiral arms similar to those observed in scattered light. If this is the case, no outer planet is needed to explain the morphology.

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