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771. A 3mm line survey in 37 IR dark clouds
ID:
ivo://CDS.VizieR/J/ApJ/756/60
Title:
A 3mm line survey in 37 IR dark clouds
Short Name:
J/ApJ/756/60
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have observed 37 Infrared Dark Clouds (IRDCs), containing a total of 159 clumps, in high-density molecular tracers at 3mm using the 22m ATNF Mopra Telescope located in Australia. After determining kinematic distances, we eliminated clumps that are not located in IRDCs and clumps with a separation between them of less than one Mopra beam. Our final sample consists of 92 IRDC clumps. The most commonly detected molecular lines are (detection rates higher than 8%) N_2_H^+^, HNC, HN^13^C, HCO^+^, H^13^CO^+^, HCN, C_2_H, HC_3_N, HNCO, and SiO. We investigate the behavior of the different molecular tracers and look for chemical variations as a function of an evolutionary sequence based on Spitzer IRAC and MIPS emission. Optical depth calculations show that in IRDC clumps the N_2_H^+^ line is optically thin, the C_2_ H line is moderately optically thick, and HNC and HCO^+^ are optically thick.
772. A 3mm molecular line survey of NGC1068
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.
773. Ammonia and CO outflow around 6.7GHz methanol masers
ID:
ivo://CDS.VizieR/J/AJ/152/92
Title:
Ammonia and CO outflow around 6.7GHz methanol masers
Short Name:
J/AJ/152/92
Date:
21 Oct 2021
Publisher:
CDS
Description:
Single point observations are presented in NH_3_ (1, 1) and (2, 2) inversion transitions using the Effelsberg 100m telescope for a sample of 100 6.7GHz methanol masers and mapping observations in the ^12^CO and ^13^CO (1-0) transitions using the Purple Mountain Observatory Delingha 13.7m telescope for 82 sample sources with detected ammonia. A further 62 sources were selected for either ^12^CO or ^13^CO line outflow identification, producing 45 outflow candidates, 29 using ^12^CO and 16 using ^13^CO data. Twenty-two of the outflow candidates were newly identified, and 23 had trigonometric parallax distances. Physical properties were derived from ammonia lines and CO outflow parameters were calculated. Histograms and statistical correlations for ammonia, CO outflow parameters, and 6.7GHz methanol maser luminosities are also presented. No significant correlation was found between ammonia and maser luminosity. However, weak correlations were found between outflow properties and maser luminosities, which may indicate that outflows are physically associated with 6.7GHz masers.
774. Ammonia in high-mass star formation regions
ID:
ivo://CDS.VizieR/J/ApJ/790/84
Title:
Ammonia in high-mass star formation regions
Short Name:
J/ApJ/790/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report systematic mapping observations of the NH_3_(1, 1) and (2, 2) inversion lines toward 62 high-mass star-forming regions using the Very Large Array (VLA) in its D and DnC array configurations. The VLA images cover a spatial dynamic range from 40'' to 3'', allowing us to trace gas kinematics from ~1 pc scales to <~ 0.1 pc scales. Based on the NH_3_ morphology and the infrared nebulosity on 1 pc scales, we categorize three subclasses in the sample: filaments, hot cores, and NH_3_-dispersed sources. The ubiquitous gas filaments found on 1 pc scales have a typical width of ~0.1 pc and often contain regularly spaced fragments along the major axis. The spacing of the fragments and the column densities is consistent with the turbulent supported fragmentation of cylinders. Several sources show multiple filaments that converge toward a center where the velocity field in the filaments is consistent with gas flows. We derive rotational temperature maps for the entire sample. For the three hot core sources, we find a projected radial temperature distribution that is best fit by power-law indices from -0.18 to -0.35. We identify 174 velocity-coherent ~0.1 pc scale dense cores from the entire sample. The mean physical properties for these cores are 1.1 km/s in intrinsic linewidth, 18 K in NH_3_ rotational temperature, 2.3x10^15^/cm2 in NH_3_gas column density, and 67 M_{sun}_in molecular mass. The dense cores identified from the filamentary sources are closer to being virialized. Dense cores in the other two categories of sources appear to be dynamically unstable.
775. Ammonia observations in G79.29+0.46
ID:
ivo://CDS.VizieR/J/A+A/564/A21
Title:
Ammonia observations in G79.29+0.46
Short Name:
J/A+A/564/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of observations of the ammonia (1,1) and (2,2) lines in a field of 7'x7' centered in the LBV ring nebula G79.29+0.46. The survey also includes a significant part of the IRDC G79.3+0.3. Data have been gathered with the 100m radio telescope at Effelsberg. Both lines have been observed simultaneously with excellent spectral resolution. A clump of the IRDC, referred in the paper as the SW region, is sampled every 20"; sampling is 40" elsewhere.
776. Ammonia on YSOs IRAS sources
ID:
ivo://CDS.VizieR/J/A+A/308/573
Title:
Ammonia on YSOs IRAS sources
Short Name:
J/A+A/308/573
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present observations of NH_3_ (1,1) and (2,2) lines in two flux-limited samples of IRAS sources selected according to colour criteria which should result in a high fraction of Young Stellar Objects. The first sample contains sources (named 'LOW') whose evolutionary status is essentially unknown, while the second sample contains sources (named 'HIGH') possibly associated with ultracompact HII regions, the distinction being based on the IRAS [25-12] colour.
777. Ammonia spectral atlas in Perseus
ID:
ivo://CDS.VizieR/J/ApJS/175/509
Title:
Ammonia spectral atlas in Perseus
Short Name:
J/ApJS/175/509
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present ammonia observations of 193 dense cores and core candidates in the Perseus molecular cloud made using the Robert F. Byrd Green Bank Telescope. We simultaneously observed the NH_3_(1,1), NH_3_(2,2), C_2_S (2_1_=>1_0_), and C^34^_2_S(2_1_=>1_0_) transitions near {nu}=23GHz for each of the targets with a spectral resolution of {delta}v~0.024km/s. We find ammonia emission associated with nearly all of the (sub)millimeter sources, as well as at several positions with no associated continuum emission. For each detection, we have measured physical properties by fitting a simple model to every spectral line simultaneously. Where appropriate, we have refined the model by accounting for low optical depths, multiple components along the line of sight, and imperfect coupling to the GBT beam. For the cores in Perseus, we find a typical kinetic temperature of T_k_=11K, a typical column density of N_NH3_~10^14.5^/cm2, and velocity dispersions ranging from {sigma}v=0.07 to 0.7km/s. However, many cores with {sigma}v>0.2km/s show evidence for multiple velocity components along the line of sight.
778. A 3.5mm polarimetric survey of radio-loud AGNs
ID:
ivo://CDS.VizieR/J/ApJS/189/1
Title:
A 3.5mm polarimetric survey of radio-loud AGNs
Short Name:
J/ApJS/189/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from the first large (>100 sources) 3.5mm polarimetric survey of radio-loud active galactic nuclei (AGNs). This wavelength is favorable within the radio-millimeter range for measuring the intrinsic linearly polarized emission from AGNs, since in general it is only marginally affected by Faraday rotation of the electric vector position angle and depolarization. The I, Q, U, and V Stokes parameter observations were performed with the XPOL polarimeter at the IRAM 30m Telescope on different observing epochs from 2005 July (when most of the measurements were made) to 2009 October. Our sample consists of 145 flat-radio-spectrum AGNs with declination >-30{deg} (J2000.0) and flux density >~1Jy at ~86GHz, as measured at the IRAM 30m Telescope from 1978 to 1994. This constraint on the radio spectrum causes our sample to be dominated by blazars, which allows us to conduct new statistical studies on this class of high-luminosity, relativistically beamed emitters. Over our entire source sample, the luminosity of the jets is anticorrelated with the degree of linear polarization. Consistent with previous findings claiming larger Doppler factors for brighter {gamma}-ray blazars, quasars listed in our sample, and in the Fermi Large Area Telescope Bright Source Catalog (LBAS, Abdo et al., 2009ApJ...700..597A), show larger luminosities than non-LBAS ones, but our data do not allow us to confirm the same for BL Lac objects. Our new data can be used to estimate the 3.5mm AGN contribution to measurements of the linear polarization of the cosmic microwave background, such as those performed by the Planck satellite.
779. Amplitude of variability for 150 YSOs in Orion
ID:
ivo://CDS.VizieR/J/ApJ/885/64
Title:
Amplitude of variability for 150 YSOs in Orion
Short Name:
J/ApJ/885/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a quantitative, empirically based argument that at least some Class I sources are low-mass, pre-main-sequence stars surrounded by spatially extended envelopes of dusty gas. The source luminosity arises principally from stellar gravitational contraction, as in optically visible pre-main-sequence stars that lack such envelopes. We base our argument on the fact that some Class I sources in Orion and other star-forming regions have been observed by Spitzer to be periodic variables in the mid-infrared, and with periods consistent with T Tauri rotation rates. Using a radiative transfer code, we construct a variety of dust envelopes surrounding rotating, spotted stars, to see whether an envelope that produces a Class I spectral energy distribution at least broadly matches the observed modulations in luminosity. Acceptable envelopes can be either spherical or flattened and may or may not have polar cavities. The key requirement is that they have a modest equatorial optical depth at the Spitzer waveband of 3.6{mu}m, typically {tau}3.6~0.6. The total envelope mass, based on this limited study, is at most about 0.1M{sun}, less than a typical stellar mass. Future studies should focus on the dynamics of the envelope, to determine whether material is actually falling onto the circumstellar disk.
780. Amplitudes of single-mode Cepheids
ID:
ivo://CDS.VizieR/J/A+A/504/959
Title:
Amplitudes of single-mode Cepheids
Short Name:
J/A+A/504/959
Date:
21 Oct 2021
Publisher:
CDS
Description:
The dependence of amplitude on the pulsation period differs from other Cepheid-related relationships. We attempt to revise the period-amplitude (P-A) relationship of Galactic Cepheids based on multi-colour photometric and radial velocity data. Reliable P-A graphs for Galactic Cepheids constructed for the U, B, V, Rc, and Ic photometric bands and pulsational radial velocity variations facilitate investigations of previously poorly studied interrelations between observable amplitudes. The effects of both binarity and metallicity on the observed amplitude, and the dichotomy between short- and long-period Cepheids can both be studied. A homogeneous data set was created that contains basic physical and phenomenological properties of 369 Galactic Cepheids. Pulsation periods were revised and amplitudes were determined by the Fourier method. P-A graphs were constructed and an upper envelope to the data points was determined in each graph. Correlations between various amplitudes and amplitude-related parameters were searched for, using Cepheids without known companions.

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