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1671. Model spectra for identifying age spreads
ID:
ivo://CDS.VizieR/J/MNRAS/505/979
Title:
Model spectra for identifying age spreads
Short Name:
J/MNRAS/505/979
Date:
22 Feb 2022
Publisher:
CDS
Description:
In this third paper of a series on the precision of obtaining ages of stellar populations using the full spectrum fitting technique, we examine the precision of this technique in deriving possible age spreads within a star cluster. We test how well an internal age spread can be resolved as a function of cluster age, population mass fraction, and signal-to-noise (S/N) ratio. For this test, the two ages (Age (SSP1) and Age (SSP2)) are free parameters along with the mass fraction of SSP1. We perform the analysis on 118,800 mock star clusters covering all ages in the range 6.8<log(age/yr)<10.2, with mass fractions from 10% to 90% for two age gaps (0.2dex and 0.5dex). Random noise is added to the model spectra to achieve S/N ratios between 50 to 100 per wavelength pixel. We find that the mean of the derived Age (SSP1) generally matches the real Age (SSP1) to within 0.1dex up to ages around log(age/yr)=9.5. The precision decreases for log(age/yr)>9.6 for any mass fraction or S/N, due to the similarity of SED shapes for those ages. In terms of the recovery of age spreads, we find that the derived age spreads are often larger than the real ones, especially for log(age/yr)<8.0 and high mass fractions of SSP1. Increasing the age gap in the mock clusters improves the derived parameters, but Age (SSP2) is still overestimated for the younger ages.
1672. Model spectra of hot stars at the pre-SN stage
ID:
ivo://CDS.VizieR/J/A+A/558/A131
Title:
Model spectra of hot stars at the pre-SN stage
Short Name:
J/A+A/558/A131
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the fundamental properties of core-collapse Supernova (SN) progenitors from single stars at solar metallicity. We combine Geneva stellar evolutionary models with initial masses of Mini=20-120M_{sun}_ with atmospheric/wind models using CMFGEN. We provide synthetic photometry and high-resolution spectra of hot stars at the pre-SN stage. For Mini=9-20M_{sun}_, we supplement our analysis using publicly available MARCS model atmospheres of RSGs. We employ observational criteria of spectroscopic classification and find that massive stars, depending on Mini and rotation, end their lives as red supergiants (RSG), yellow hypergiants (YHG), luminous blue variables (LBV), and Wolf-Rayet (WR) stars of the WN and WO spectral types. For rotating models, we obtain the following types of SN progenitors: WO1-3 (Mini<=32M_{sun}_), WN10-11 (25<Mini< 32M_{sun}_), LBV (20<=Mini<25M_{sun}_), G1 Ia+ (18<Mini<20M_{sun}_), and RSGs (9<=Mini<=18M_{sun}_). For non-rotating models, we find spectral types WO1-3 (Mini>40M_{sun}_), WN7-8 (25<Mini<=40M_{sun}_), WN11h/LBV (20<Mini<=25M_{sun}_), and RSGs (9<=Mini<=20M_{sun}_). Our rotating models indicate that SN IIP progenitors are all RSG, SN IIL/b progenitors are 56% LBVs and 44% YHGs, SN Ib progenitors are 96% WN10-11 and 4% WOs, and SN Ic progenitors are all WO stars. We find that not necessarily the most massive and luminous SN progenitors are the brighter ones in a given filter. We show that SN IIP progenitors (RSGs) are bright in the RIJHK_S filters and faint in the UB filters. SN IIL/b progenitors (LBVs and YHGs), and SN Ib progenitors (WNs) are relatively bright in optical/IR filters, while SN Ic progenitors (WOs) are faint in all optical filters. We argue that SN Ib and Ic progenitors from single stars should be undetectable in the available pre-explosion images with the current magnitude limits, in agreement with observational results.
1673. Molecular absorption lines in PKS 1830-211
ID:
ivo://CDS.VizieR/J/A+A/574/A108
Title:
Molecular absorption lines in PKS 1830-211
Short Name:
J/A+A/574/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
Based on measurements with the Effelsberg 100-m telescope, a multiline study of molecular species is presented toward the southwestern source of the gravitational lens system PKS 1830-211, which is by far the best known target for studying molecular gas in absorption at intermediate redshift. Determining line parameters and optical depths and performing large velocity gradient radiative transfer calculations, the aims of this study are (1) to evaluate physical parameters of the absorbing foreground gas at z~0.89, in particular its homogeneity, and (2) to monitor the spectroscopic time variability caused by fluctuations in the z~2.5 background continuum source.
1674. Molecular clumps CO, HCO and HCN data
ID:
ivo://CDS.VizieR/J/other/RAA/20.115
Title:
Molecular clumps CO, HCO and HCN data
Short Name:
J/other/RAA/20.1
Date:
19 Jan 2022 00:26:13
Publisher:
CDS
Description:
Gravitational accretion accumulates the original mass. This process is crucial for us to understand the initial phases of star formation. Using the specific infall profiles in optically thick and thin lines, we searched the clumps with infall motion from the Milky Way Imaging Scroll Painting (MWISP) CO data in previous work. In this study, we selected 133 sources as a sub-sample for further research and identification. The excitation temperatures of these sources are between 7.0 and 38.5K, while the H_2_ column densities are between 10^21^ and 10^23^cm^-2^. We have observed optically thick lines HCO+(1-0) and HCN(1-0) using the DLH 13.7-m telescope, and found 56 sources with a blue profile and no red profile in these two lines, which are likely to have infall motions, with a detection rate of 42%. This suggests that using CO data to restrict the sample can effectively improve the infall detection rate. Among these confirmed infall sources are 43 associated with Class 0/I young stellar objects (YSOs), and 13 which are not. These 13 sources are probably associated with the sources in the earlier evolutionary stage. In comparison, the confirmed sources that are associated with Class 0/I YSOs have higher excitation temperatures and column densities, while the other sources are colder and have lower column densities. Most infall velocities of the sources that we confirmed are between 10^-1^ to 100km/s, which is consistent with previous studies.
1675. Molecular gas content of spiral galaxies
ID:
ivo://CDS.VizieR/J/A+A/327/522
Title:
Molecular gas content of spiral galaxies
Short Name:
J/A+A/327/522
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 12CO(J=1-0) line observations of 73 spiral galaxies mostly in the Coma/A1367 supercluster. From these data, combined with data available in the literature, we extract the first complete, optically selected sample (mpg<15.2) of 37 isolated and of 27 cluster galaxies. The 12CO(1-0) line spectra are accessible as postscript figures.
1676. Molecular ions in L1157-B1
ID:
ivo://CDS.VizieR/J/A+A/565/A64
Title:
Molecular ions in L1157-B1
Short Name:
J/A+A/565/A64
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we perform a complete census of molecular ions with an abundance larger than ~10^-10^ in the protostellar shock L1157-B1. This allows us to study the ionization structure and chemistry of the shock. An unbiased high-sensitivity survey of L1157-B1 performed with the IRAM-30m and Herschel/HIFI as part of the CHESS and ASAI large programs allows searching for molecular ions emission. Then, by means of a radiative transfer code in the Large Velocity Gradient approximation, the gas physical conditions and fractional abundances of molecular ions are derived. The latter are compared with estimates of steady-state abundances in the cloud and their evolution in the shock calculated with the chemical model Astrochem.
1677. Molecular lines in EGOs
ID:
ivo://CDS.VizieR/J/ApJ/710/150
Title:
Molecular lines in EGOs
Short Name:
J/ApJ/710/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the first systematic survey of molecular lines (including HCO^+^(1-0) and ^12^CO, ^13^CO, C^18^O(1-0) lines at the 3mm band) toward a new sample of 88 massive young stellar object (MYSO) candidates associated with ongoing outflows (known as extended green objects or EGOs) identified from the Spitzer GLIMPSE survey in the northern hemisphere with the Purple Mountain Observatory 13.7m radio telescope. By analyzing the asymmetries of the optically thick line HCO^+^ for 69 of 72 EGOs with HCO^+^ detection, we found 29 sources with "blue asymmetric profiles" and 19 sources with "red asymmetric profiles."
1678. Molecular lines in 4 IRCS clumps
ID:
ivo://CDS.VizieR/J/A+A/570/A51
Title:
Molecular lines in 4 IRCS clumps
Short Name:
J/A+A/570/A51
Date:
21 Oct 2021
Publisher:
CDS
Description:
The earliest phases of high-mass star formation are poorly understood. Aims. Our goal is to determine the physical conditions and kinematic structure of massive starforming cloud clumps. We analyse H_2_O 557GHz line profiles observed with HIFI toward four positions in two infrared-dark cloud clumps. By comparison with ground-based C_17_O, N_2_H^+^, CH_3_OH, and NH_3_ line observations, we constrain the volume density and kinetic temperature of the gas and estimate the column density and abundance of H_2_O and N_2_H^+^. The observed water lines are complex with emission and absorption components. The absorption is redshifted and consistent with a cold envelope, while the emission is interpreted as resulting from proto-stellar outflows. The gas density in the clumps is ~10^7^cm^-3^. The o-H_2_O outflow column density is 0.3-3.0x10^14^cm^-2^. The o-H_2_O absorption column density is between 1.5x10^14^ and 2.6x10^15^cm^-2^ with cold o-H_2_O abundances between 1.5x10^-9^ and 3.1x10^-8^. All clumps have high gas densities (~10^7^cm^-3^) and display infalling gas. Three of the four clumps have outflows. The clumps form an evolutionary sequence as probed by H_2_O N_2_H+, NH_3_, and CH_3_OH. We find that G28-MM is the most evolved, followed by G11-MM and then G28-NH3. The least evolved clump is G11-NH3 which shows no signposts of starformation; G11-NH3 is a high-mass pre-stellar core.
1679. Molecular lines in 5 massive dense cores
ID:
ivo://CDS.VizieR/J/A+A/504/853
Title:
Molecular lines in 5 massive dense cores
Short Name:
J/A+A/504/853
Date:
21 Oct 2021
Publisher:
CDS
Description:
Two mid-infrared quiet and two brighter massive cores were observed in various transitions (E_up_ up to 289K) of CS, OCS, H_2_S, SO, and SO_2_ and of their ^34^S isotopologues at mm wavelengths with the IRAM 30m and CSO telescopes. The 1D modeling of the dust continuum is used to derive the density and temperature laws, which were then applied in the RATRAN code to modeling the observed line emission and to deriving the relative abundances of the molecules. All lines are detected, except the highest energy SO_2_ transition. Infall (up to 2.9km/s) may be detected towards the core W43MM1. We propose an evolutionary sequence of our sources (W43MM1 - IRAS18264-1152 - IRAS05358+3543 - IRAS18162-2048), based on the SED analysis. The analysis of the variations in abundance ratios from source to source reveals that the SO and SO_2_ relative abundances increase with time, while CS and OCS decrease. Molecular ratios, such as [OCS/H_2_S], [CS/H_2_S], [SO/OCS], [SO_2_/OCS], [CS/SO], and [SO_2_/SO] may be good indicators of evolution, depending on layers probed by the observed molecular transitions. Observations of molecular emission from warmer layers, so that involving higher upper energy levels must be included.
1680. Monitoring AGNs with H{beta} Asymmetry (MAHA). I.
ID:
ivo://CDS.VizieR/J/ApJ/869/142
Title:
Monitoring AGNs with H{beta} Asymmetry (MAHA). I.
Short Name:
J/ApJ/869/142
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have started a long-term reverberation mapping (RM) project using the Wyoming Infrared Observatory 2.3m telescope titled "Monitoring AGNs with H{beta} Asymmetry" (MAHA). The motivations of the project are to explore the geometry and kinematics of the gas responsible for complex H{beta} emission-line profiles, ideally leading to an understanding of the structures and origins of the broad-line region (BLR). Furthermore, such a project provides the opportunity to search for evidence of close binary supermassive black holes. We describe MAHA and report initial results from our first campaign, from 2016 December to 2017 May, highlighting velocity-resolved time lags for four active galactic nuclei (AGNs) with asymmetric H{beta} lines. We find that 3C120, Ark120, and Mrk6 display complex features different from the simple signatures expected for pure outflow, inflow, or a Keplerian disk. While three of the objects have been previously reverberation mapped, including velocity-resolved time lags in the cases of 3C120 and Mrk6, we report a time lag and corresponding black hole mass measurement for SBS1518+593 for the first time. Furthermore, SBS1518+593, the least asymmetric of the four, does show velocity-resolved time lags characteristic of a Keplerian disk or virialized motion more generally. Also, the velocity-resolved time lags of 3C120 have significantly changed since previously observed, indicating an evolution of its BLR structure. Future analyses of the data for these objects and others in MAHA will explore the full diversity of H{beta} lines and the physics of AGN BLRs.

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