- ID:
- ivo://CDS.VizieR/J/ApJ/707/103
- Title:
- Observation of Ser FIRS 1 at 230GHz
- Short Name:
- J/ApJ/707/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a program to characterize the disk and envelope structure of typical Class 0 protostars in nearby low-mass star-forming regions. We use Spitzer Infrared Spectrograph (IRS) mid-infrared spectra, high-resolution Combined Array for Research in Millimeter-wave Astronomy (CARMA) 230GHz continuum imaging, and two-dimensional radiative transfer models to constrain the envelope structure, as well as the size and mass of the circumprotostellar disk in Serpens FIRS 1. The primary envelope parameters (centrifugal radius, outer radius, outflow opening angle, and inclination) are well constrained by the spectral energy distribution (SED), including Spitzer IRAC and MIPS photometry, IRS spectra, and 1.1mm Bolocam photometry. These together with the excellent uv-coverage (4.5-500k{lambda}) of multiple antenna configurations with CARMA allow for a robust separation of the envelope and a resolved disk. The SED of Serpens FIRS 1 is best fit by an envelope with the density profile of a rotating, collapsing spheroid with an inner (centrifugal) radius of approximately 600AU, and the millimeter data by a large resolved disk with M_disk_~1.0M_{sun}_ and R_disk_~300AU.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/778/16
- Title:
- Observations of HCO^+^ in NGC 7293
- Short Name:
- J/ApJ/778/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The J=1->0 transition of HCO^+^ at 89GHz has been mapped across the Helix Nebula (NGC 7293) with 70" spatial resolution (1.68km/s velocity resolution) using the Arizona Radio Observatory 12m telescope. This work is the first large-scale mapping project of a dense gas tracer (n(H_2_)~10^5^/cm3) in old planetary nebulae. Observations of over 200 positions encompassing the classical optical image were conducted with a 3{sigma} noise level of ~20mK. HCO^+^ was detected at most positions, often exhibiting multiple velocity components indicative of complex kinematic structures in dense gas. The HCO^+^ spectra suggest that the Helix is composed of a bipolar, barrel-like structure with red- and blue-shifted halves, symmetric with respect to the central star and oriented ~10{deg} east from the line of sight. A second bipolar, higher velocity outflow exists as well, situated along the direction of the Helix "plumes." The column density of HCO^+^ across the Helix is N_tot_~1.5x10^10^-5.0x10^11^/cm2, with an average value N_ave_~1x10^11^/cm2, corresponding to an abundance, relative to H_2_, of f~1.4x10^-8^. This value is similar to that observed in young PN, and contradicts chemical models, which predict that the abundance of HCO^+^ decreases with nebular age. This study indicates that polyatomic molecules readily survive the ultraviolet field of the central white dwarf, and can be useful in tracing nebular morphology in the very late stages of stellar evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/138
- Title:
- Observed transitions of CH_3_OH and CH_3_CHO
- Short Name:
- J/ApJ/880/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAM 30m Observations toward eight protostellar outflow sources were taken in the 96-176GHz range. Transitions of CH_3_OH and CH_3_CHO were detected in seven of them. The integrated emissions of the transitions of each species that fell into the observed frequency range were measured and fit using RADEX and LTE models. Column densities and gas properties inferred from this fitting are presented. The ratio of the A and E-type isomers of CH_3_OH indicates that the methanol observed in these outflows was formed on the grain surface. Both species demonstrate a reduction of terminal velocity in their line profiles in faster outflows, indicating destruction in the post-shock gas phase. This destruction, and a near constant ratio of the CH_3_OH and CH_3_CHO column densities, imply it is most likely that CH_3_CHO also forms on the grain surface.
- ID:
- ivo://CDS.VizieR/J/A+A/655/L2
- Title:
- OGHReS 12CO(2-1) data cubes
- Short Name:
- J/A+A/655/L2
- Date:
- 10 Mar 2022 07:17:54
- Publisher:
- CDS
- Description:
- Filaments are a ubiquitous morphological feature of the molecular interstellar medium and are identified as sites of star formation. In recent years, more than 100 large-scale filaments (with length >10pc) have been observed in the inner Milky Way. As they appear linked to Galactic dynamics, studying those structures represents an opportunity to link kpc-scale phenomena to the physics of star formation, which operates on much smaller scales. In this letter, we use newly acquired Outer Galaxy High Resolution Survey (OGHReS) ^12^CO(2-1) data to demonstrate that a significant number of large-scale filaments are present in the outer Galaxy as well. The 37 filaments identified appear tightly associated to inter-arm regions. In addition, their masses and linear masses are, on average, one order of magnitude lower than similar-sized molecular filaments located in the inner Galaxy, showing that Milky Way dynamics is able to create very elongated features in spite of the lower gas supply in the Galactic outskirts.
- ID:
- ivo://CDS.VizieR/J/A+A/459/85
- Title:
- O/H and gas densities in star-forming galaxies
- Short Name:
- J/A+A/459/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Generally the gas metallicity in distant galaxies can only be inferred by using a few prominent emission lines. Various theoretical models have been used to predict the relationship between emission line fluxes and metallicity, suggesting that some line ratios can be used as diagnostics of the gas metallicity in galaxies. However, accurate empirical calibrations of these emission line flux ratios from real galaxy spectra spanning a wide metallicity range are still lacking. In this paper we provide such empirical calibrations by using the combination of two sets of spectroscopic data: one consisting of low-metallicity galaxies with a measurement of [O III]{lambda}4363 taken from the literature, including spectra from the Sloan Digital Sky Survey (SDSS), and the other one consisting of galaxies in the SDSS database whose gas metallicity has been determined from various strong emission lines in their spectra. This combined data set constitutes the largest sample of galaxies with information on the gas metallicity available so far and spanning the widest metallicity range. By using these data we obtain accurate empirical relations between gas metallicity and several emission line diagnostics, including the R23 parameter, the [NII]{lambda}6584/H{alpha} and [O III]{lambda}5007/[NII]{lambda}6584 ratios.
636. OH masers in W3(OH)
- ID:
- ivo://CDS.VizieR/J/ApJ/668/331
- Title:
- OH masers in W3(OH)
- Short Name:
- J/ApJ/668/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies of methanol and ground-state OH masers at very high spectral resolution have shed new light on small-scale maser processes. The nearby source W3(OH), which contains numerous bright masers in several different transitions, provides an excellent laboratory for high spectral resolution techniques. We present a model of W3(OH) based on European VLBI Network (EVN) observations of the rotationally excited 6030 and 6035MHz OH masers taken at 0.024km/s spectral resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/406/L47
- Title:
- 17OH spin-rotation transition frequencies
- Short Name:
- J/A+A/406/L47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The frequencies and line strengths of the ^2^{Pi}_3/2_ J=5/2-3/2 rotational transition of ^17^OH have been calculated from an analysis of its far-infrared laser magnetic resonance spectrum. These results have been used to make the first detection of a pure rotational transition of ^17^OH in the ISM. Two resolved components of this transition appear in absorption towards the giant molecular cloud Sagittarius B2, which was observed at a spectral resolution of 33km/s with the Fabry-Perot mode of the ISO Long Wavelength Spectrometer. The corresponding transition of ^18^OH was also observed and its line shape was modelled using HI measurements. The ^18^O/^17^O ratio of 3.5 was then used to compare this with the observed ^17^OH line shape.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A118
- Title:
- OH-streamer in SgrA at 1665 and 1667MHz
- Short Name:
- J/A+A/582/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the structure and kinematics of the OH-streamer and the +80km/s cloud and their interactions with the circumnuclear disk (CND) and with other molecular clouds in the vicinity of the Galactic centre (GC), and we map OH absorption at about 6" resolution at R<=10pc from the GC, with about 9km/s of velocity resolution. The VLA was used to map OH line absorption at the 1665 and 1667MHz lambda doublet main lines of the ^2^{PI}_3/2_ state towards the Sagittarius A complex.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/55
- Title:
- OI, GeII, KrI & H abundances from HST UV spectra
- Short Name:
- J/ApJ/872/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a survey of archived ultraviolet spectra of 100 stars recorded by the echelle spectrograph of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we measure the strengths of the weak absorption features of OI, GeII, and KrI in the interstellar medium. Our objective is to undertake an investigation that goes beyond earlier abundance studies to see how these elements are influenced independently by three different environmental properties: (1) values of a generalized atomic depletion factor F_*_ due to condensations onto dust grains (revealed here by the abundances of Mg and Mn relative to H), (2) the fraction of H atoms in the form of H_2_/f(H_2_), and (3) the ambient intensity I of ultraviolet starlight relative to an average value in our part of the Galaxy I_0_. As expected, the gas-phase abundances of all three elements exhibit negative partial correlations with F*. The abundances of free O atoms show significant positive partial correlations with logf(H_2_) and log(I/I_0_), while Ge and Kr exhibit negative partial correlations with log(I/I_0_) at marginal levels of significance. After correcting for these trends, the abundances of O relative to H show no significant variations with location, except for the already-known radial gradient of light-element abundances in the Milky Way. A comparison of Ge and O abundances revealed no significant regional enhancements or deficiencies of neutron-capture elements relative to {alpha}-process ones.
- ID:
- ivo://CDS.VizieR/VII/106
- Title:
- Open Cluster Interstellar Matter Database
- Short Name:
- VII/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a compilation of the characteristics of 128 open clusters and the interstellar medium associated with them. It is distributed as the "OCISM Database" which is the set of data files, processing and analysis software written in FORTRAN, and the supporting documentation. As provided by the author, the data are in a multi-record format which is best accessed with the author's software. The clusters in this database have been relatively well-studied, have declinations greater than -20 deg., are between 1 and 5 kpc distant, and are younger than 100 million years old. Characteristics compiled for these clusters include cluster identification, spatial coordinates, radial velocities (of stellar clusters, H II regions, and molecular clouds), proper motions, distance, angular diameter, linear diameter, age, mass (based on stellar and atomic gas, ionized gas, molecular clouds, and dust determinations), visual extinction, and reddening.
