- ID:
- ivo://CDS.VizieR/J/ApJS/109/489
- Title:
- OH observations of Arecibo OH/IR stars
- Short Name:
- J/ApJS/109/489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Arecibo 1612MHz survey of a complete sample of color-selected IRAS sources with 25{mu}m fluxes S(25)>2 Jy detected 393 OH/IR stars. A complementary 1667 and 1665MHz OH survey of these objects is presented here. Main-line masers have been detected in 238 surveyed objects: 18 exhibit only 1665MHz emission, 220 exhibit 1667MHz masers, and 119 exhibit both. The main lines were not detected in 159 objects.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/123/2772
- Title:
- OH-selected AGB and post-AGB objects. I.
- Short Name:
- J/AJ/123/2772
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using 766 compact objects found in a systematic survey of the Galactic plane in the 1612MHz masing OH line, new light is cast on the IR properties of evolved stars on the thermally pulsing asymptotic giant branch (AGB) and beyond. The usual mid-IR selection criteria for post-AGB, based on IRAS colors, largely fail to distinguish early post-AGB stages. A two-color diagram from much narrower band MSX flux densities, with bimodal distributions, provides a better tool for doing this. Four mutually consistent selection criteria for OH-masing red protoplanetary nebulae are given, as well as two for early post-AGB masers and one for all post-AGB masers including the earliest ones. All these criteria miss a group of blue, high-outflow post-AGB sources with 60{mu}m excess; these will be discussed in detail in Paper II (Sevenster, 2002AJ....123.2772S). The majority of post-AGB sources show regular double-peaked spectra in the OH 1612MHz line, with fairly low outflow velocities, although the fractions of single peaks and irregular spectra may vary with age and mass. The OH flux density shows a fairly regular relation with the stellar flux and the envelope optical depth, with the maser efficiency increasing with IRAS color R_21_. The OH flux density is linearly correlated with the 60{mu}m flux density.
- 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/ApJ/549/155
- Title:
- [OIII] emission in a sample of AGNs
- Short Name:
- J/ApJ/549/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The emission-line flux ratio of [OIII]4363/[OIII]5007 (R_OIII_) is a useful diagnostic for the ionization mechanism and physical properties of emission-line regions in active galactic nuclei (AGNs). However, it is known that simple photoionization models underpredict the [OIII]4363 intensity, being inconsistent with observations. In this paper we report on several pieces of evidence that a large fraction of the [OIII]4363 emission arises from the dense gas obscured by putative tori: (1) the visibility of high-R_OIII_ regions is correlated to that of broad-line regions, (2) higher R_OIII_ objects show hotter mid-infrared colors, (3) higher R_OIII_ objects show stronger highly ionized emission lines such as [FeVII] 6087 and [FeX]6374, and (4) higher R_OIII_ objects have broader line width of [OIII]4363 normalized by that of [OIII]5007.
- ID:
- ivo://CDS.VizieR/J/A+A/596/A26
- Title:
- OMC-2 FIR 3 and FIR 4 [OI] maps
- Short Name:
- J/A+A/596/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detection of a jet in the far-IR [OI] lines from an intermediate mass protostar. We have carried out a Herschel/PACS spectral mapping study in the [OI] lines of OMC-2 FIR 3 and FIR 4, two of the most luminous protostars in Orion outside of the Orion Nebula. The spatial morphology of the fine structure line emission reveals the presence of an extended photodissociation region (PDR) and a narrow, but intense jet emission connecting the two protostars. The jet seen in [OI] emission is spatially aligned with the Spitzer/IRAC 4.5um jet and the CO (6-5) molecular outflow centered on FIR 3. The mass loss rate derived from the total [OI] 63um line luminosity of the jet is 7.7*10^-6^M_{sun}_/yr, which is more than an order of magnitude higher than that measured for typical low mass class 0 protostars. The implied accretion luminosity is significantly higher than the observed bolometric luminosity of FIR 4, indicating that the [OI] jet is unlikely to be associated with FIR 4. We argue that the peak line emission seen toward FIR 4 originates in the terminal shock produced by the jet driven by FIR 3. The higher mass loss rate that we find for FIR 3 is consistent with the idea that intermediate mass protostars drive more powerful jets than their low-mass counterparts. Our results also call into question the nature of FIR 4.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A136
- Title:
- OMC-2 FIR4 fits images
- Short Name:
- J/A+A/657/A136
- Date:
- 21 Mar 2022 09:38:35
- Publisher:
- CDS
- Description:
- Isotopic fractionation is an important tool for investigating the chemical history of our Solar System. In particular, the isotopic fraction of nitrogen (^14^N/^15^N) is lower in comets and other pristine Solar System bodies with respect to the value measured for the protosolar nebula, suggesting a local chemical enrichment of ^15^N during the formation of the Solar System. Therefore, interferometric studies of nitrogen fractionation in Solar System precursors are needed for us to obtain clues about our astrochemical origins. In this work we have investigated the variation in the ^14^N/^15^N ratio in one of the closest analogues of the environment in which the Solar System was born: the protocluster OMC-2 FIR4. We present the first comparison at high angular resolution between HCN and N_2_H^+^ using interferometric data. We analysed observations of the HCN isotopologues H^13^CN and HC^15^N in the OMC-2 FIR4 protocluster. Specifically, we observed the transitions H^13^CN (1-0) and HC^15^N (1-0) with the NOrthern Extended Millimeter Array (NOEMA) within the context of the IRAM Seeds Of Life In Space (SOLIS) Large Program. We combined our results with analysis of archival data obtained with the Atacama Large Millimeter Array (ALMA) of N_2_H^+^ and its ^15^N isotopologues. Our results show a small regional variation in the ^14^N/^15^N ratio for HCN, from ~250 to 500. The ratios in the central regions of FIR4, where the candidate protostars are located, are largely consistent with one another and within that range (~300). They also show little variation from the part of the protocluster known to harbour a high cosmic-ray ionisation rate to the portion with a lower rate. We also found a small variation in the ^14^N/^15^N ratio of N_2_H^+^ across different regions, from ~200 to ~400. These results suggest that local changes in the physical parameters occurring on the small linear scales probed by our observations in the protocluster do not seem to affect the ^14^N/^15^N ratio in either HCN or N_2_H^+^ and hence that this is independent of the molecule used. Moreover, the high level of irradiation due to cosmic rays does not affect the N fractionation either.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1395
- Title:
- omega Cen Spitzer photometry
- Short Name:
- J/AJ/135/1395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Spitzer Space Telescope imaging survey of the most massive Galactic globular cluster, {omega} Centauri, and investigate stellar mass loss at low metallicity and the intracluster medium (ICM). The survey covers approximately 3.2x the cluster half-mass radius at 3.6, 4.5, 5.8, 8, and 24um, resulting in a catalog of over 40000 point sources in the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/160/282
- Title:
- Optical and IR spectroscopy of Europa
- Short Name:
- J/AJ/160/282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The composition of Europa's trailing hemisphere reflects the combined influences of endogenous geologic resurfacing and exogenous sulfur radiolysis. Using spatially resolved visible-wavelength spectra of Europa obtained with the Hubble Space Telescope, we map multiple spectral features across the trailing hemisphere and compare their geographies with the distributions of large-scale geology, magnetospheric bombardment, and surface color. Based on such comparisons, we interpret some aspects of our spectra as indicative of purely exogenous sulfur radiolysis products and other aspects as indicative of radiolysis products formed from a mixture of endogenous material and magnetospheric sulfur. The spatial distributions of two of the absorptions seen in our spectra-a widespread downturn toward the near-UV and a distinct feature at 530nm-appear consistent with sulfur allotropes previously suggested from ground-based spectrophotometry. However, the geographies of two additional features-an absorption feature at 360nm and the spectral slope at red wavelengths-are more consistent with endogenous material that has been altered by sulfur radiolysis. We suggest irradiated sulfate salts as potential candidates for this material, but we are unable to identify particular species with the available data.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/62
- Title:
- Optical and NIR spectra and LCs of SN2016ija
- Short Name:
- J/ApJ/853/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our analysis of the Type II supernova DLT16am (SN2016ija). The object was discovered during the ongoing D<40Mpc (DLT40) one-day cadence supernova search at r~20.1mag in the "edge-on" nearby (D=20.0+/-4.0Mpc) galaxy NGC1532. The subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extinguished transient, with E(B-V)=1.95+/-0.15mag, consistent with a standard extinction law with R_V_=3.1 and a bright (M_V_=-18.48+/-0.77mag) absolute peak magnitude. A comparison of the photometric features with those of large samples of SNe II reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of S_50V_=0.84+/-0.04mag/50days, consistent with the photometric properties typical of those of fast-declining SNeII. Despite the large uncertainties on the distance and the extinction in the direction of DLT16am, the measured photospheric expansion velocity and the derived absolute V-band magnitude at ~50days after the explosion match the existing luminosity-velocity relation for SNeII.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A9
- Title:
- Optical and NIR spectra of SN iPTF13ebh
- Short Name:
- J/A+A/578/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (NIR) time-series spectroscopy, as well as complementary ultraviolet (UV), optical, and NIR data, of the Type Ia supernova (SN Ia) iPTF13ebh, which was discovered within two days from the estimated time of explosion. The first NIR spectrum was taken merely 2.3 days after explosion and may be the earliest NIR spectrum yet obtained of a SN Ia. The most striking features in the spectrum are several NIR CI lines, and the CI {lambda}1.0693um line is the strongest ever observed in a SN Ia. Interestingly, no strong optical CII counterparts were found, even though the optical spectroscopic time series began early and is densely-cadenced. Except at the very early epochs, within a few days from the time of explosion, we show that the strong NIR CI compared to the weaker optical CII appears to be general in SNe Ia. iPTF13ebh is a fast decliner with {Delta}m15(B)=1.79+/-0.01, and its absolute magnitude obeys the linear part of the width-luminosity relation. It is therefore categorized as a "transitional" event, on the fast-declining end of normal SNe Ia as opposed to subluminous/91bg-like objects. iPTF13ebh shows NIR spectroscopic properties that are distinct from both the normal and subluminous/91bg-like classes, bridging the observed characteristics of the two classes. These NIR observations suggest composition and density of the inner core similar to that of 91bg-like events, and a deep reaching carbon burning layer not observed in slower declining SNe Ia. There is also a substantial difference between the explosion times inferred from the early-time light curve and the velocity evolution of the SiII {lambda}0.6355um line, implying a long dark phase of ~4 days.
