- ID:
- ivo://CDS.VizieR/J/ApJS/122/221
- Title:
- A mid-IR survey of Proto-PNs Candidates
- Short Name:
- J/ApJS/122/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the data from a mid-infrared (MIR) imaging survey of 66 proto-planetary nebula candidates using two MIR cameras (MIRAC2 and Berkcam) at the NASA Infrared Telescope Facility and the United Kingdom Infrared Telescope. The goal of this survey is to determine the size, flux, and morphology of the MIR emission regions, which sample the inner regions of the circumstellar dust shells of protoplanetary nebulae. We imaged these protoplanetary nebulae with narrowband filters({delta}{lambda}/{lambda}{=~}10%) at wavelengths of notable dust features. With our typical angular resolution of 1'', we resolve 17 sources, find 48 objects unresolved, and do not detect one source. For several sources we checked optical and infrared associations and positions of the sources. In table format, we list the size and flux measurements for all of the detected objects and show figures of all of the resolved sources. The proto-planetary nebula candidate sample includes, in addition to the predominant proto-planetary nebulae, extreme asymptotic giant branch stars, young planetary nebulae, a supergiant, and a luminous blue variable. We find that dust shells that are cooler (T{=~}150 K) and brighter in the infrared are more easily resolved. Eleven of the seventeen resolved sources are extended and fall into one of two types of MIR morphological classes: core/elliptical or toroidal. Core/elliptical structures show unresolved cores with lower surface brightness elliptical nebulae. Toroidal structures show limb-brightened peaks suggesting equatorial density enhancements. We argue that core/ellipticals have denser dust shells than toroidals.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/900/9
- Title:
- AMIGA: The Circumgalactic Medium of Andromeda
- Short Name:
- J/ApJ/900/9
- Date:
- 14 Mar 2022 07:38:05
- Publisher:
- CDS
- Description:
- Project AMIGA (Absorption Maps In the Gas of Andromeda) is a survey of the circumgalactic medium (CGM) of Andromeda (M31, R_vir_~300kpc) along 43 QSO sightlines at impact parameters 25<~R<~569kpc (25 at R<~R_vir_). We use ultraviolet absorption measurements of SiII, SiIII, SiIV, CII, and CIV from the Hubble Space Telescope/Cosmic Origins Spectrograph and OVI from the Far Ultraviolet Spectroscopic Explorer to provide an unparalleled look at how the physical conditions and metals are distributed in the CGM of M31. We find that SiIII and OVI have a covering factor near unity for R<~1.2R_vir_ and <~1.9R_vir_, respectively, demonstrating that M31 has a very extended ~104-105.5K ionized CGM. The metal and baryon masses of the 104-105.5K CGM gas within R_vir_ are >~108 and >~4x1010 (Z/0.3Z{sun})-1M{sun}, respectively. There is not much azimuthal variation in the column densities or kinematics, but there is with R. The CGM gas at R<~0.5R_vir_ is more dynamic and has more complicated, multiphase structures than at larger radii, perhaps a result of more direct impact of galactic feedback in the inner regions of the CGM. Several absorbers are projected spatially and kinematically close to M31 dwarf satellites, but we show that those are unlikely to give rise to the observed absorption. Cosmological zoom simulations of ~L* galaxies have OVI extending well beyond R_vir_ as observed for M31 but do not reproduce well the radial column density profiles of the lower ions. However, some similar trends are also observed, such as the lower ions showing a larger dispersion in column density and stronger dependence on R than higher ions. Based on our findings, it is likely that the Milky Way has a ~104-105.5K CGM as extended as for M31 and their CGM (especially the warm-hot gas probed by OVI) are overlapping.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/893
- Title:
- AMI-LA 16 GHz sources in Perseus region
- Short Name:
- J/MNRAS/415/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Perseus molecular cloud by the Spitzer c2d programme at a wavelength of 1.8cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). We detect 72% of Class 0 objects from this sample and 31% of Class I objects. No starless cores are detected. We use the flux densities measured from these data to improve constraints on the correlations between radio luminosity and bolometric luminosity, infrared luminosity and, where measured, outflow force. We discuss the differing behaviour of these objects as a function of protostellar class and investigate the differences in radio emission as a function of core mass. Two of four possible very low luminosity objects (VeLLOs) are detected at 1.8cm.
- 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.
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/143/28
- Title:
- Analysis of B6-A9 stars from INES UV spectra
- Short Name:
- J/AJ/143/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Main-sequence (MS) and giant late-B and early-A type stars are the best targets for searching for nearby interstellar (IS) SiIV and CIV resonance lines because they are not able to produce them, either in atmospheric layers or in their circumstellar environment, and because many stars of these spectral types are nearby and located in the local interstellar medium (LISM). In addition, the use of certain stars hotter than B6 can lead to misinterpretations (e.g., alpha Arae). This work analyzes the reliable Short-Wavelength Prime (SWP) high-resolution UV spectra of 558 B6-A9 type stars observed by the International Ultraviolet Explorer at distances lower than 400pc from the Sun. For the first time, this work utilizes the entire INES database to extract stellar and IS information in a systematic way from homogeneous data. Stars were classified into seven groups: normal (MS and subgiant), giant, peculiar, emission line, Algols, pre-main sequence or Herbig Ae/Be, and shell stars. Only 10 normal stars, located beyond 90pc, show weak SiIV and CIV absorptions and are clustered around the direction of Sco-Cen, while 85 located closer than 90pc, as well as another 89 beyond 90pc, do not show any absorptions at all.
- ID:
- ivo://CDS.VizieR/J/A+A/490/213
- Title:
- 1.4 and 3.4mm interferometry of W3 IRS5
- Short Name:
- J/A+A/490/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of PdBI 1.4 and 3.4mm interferometric observations of the high-mass star-forming region W3 IRS5 in the AB configurations. From the continuum maps we identified five individual sources with counterparts in the NIR, MIR or radio (Q-band), except for one source that is a new identification. Three of the sources are within the inner 2100AU, where the protostellar number density exceeds 10^6^ protostars pc^-3^ assuming spherical symmetry. Lower limits for the circumstellar masses of the sources range from ~0.3 to ~40M_{sun}_ although they were strongly affected by the spatial filtering of the interferometer. We mapped the SiO(2-1), SiO(5-4), SO2(22-22), and SO2(8-9) molecular transitions. We identify five molecular outflows in SiO, two of them nearly in the line of sight direction. The SO2 velocity structure indicates a rotating, bound system, and we find tentative signatures of converging flows as predicted by the gravoturbulent star formation and converging flow theories. The obtained data strongly indicate that the clustered environment has a major influence on the formation of high-mass stars; however, our data do not clearly allow us to distinguish whether the ongoing star-forming process follows a monolithic collapse or a competitive accretion mechanism.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/4274
- Title:
- Angular sizes of AGN cores at 2-43GHz
- Short Name:
- J/MNRAS/452/4274
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured the angular sizes of radio cores of active galactic nuclei (AGN) and analyzed their sky distributions and frequency dependencies to study synchrotron opacity in AGN jets and the strength of angular broadening in the interstellar medium. We have used archival very long baseline interferometry (VLBI) data of more than 3000 compact extragalactic radio sources observed at frequencies, {nu}, from 2 to 43GHz to measure the observed angular size of VLBI cores. We have found a significant increase in the angular sizes of the extragalactic sources seen through the Galactic plane (|b|<10{deg}) at 2, 5 and 8GHz, about 1/3 of which show significant scattering. These sources are mainly detected in directions to the Galactic bar, the Cygnus region, and a region with galactic longitudes 220{deg}<l<260{deg} (the Fitzgerald window). The strength of interstellar scattering of the AGNs is found to correlate with the Galactic H{alpha} intensity, free-electron density, and Galactic rotation measure. The dependence of scattering strengths on source redshift is insignificant, suggesting that the dominant scattering screens are located in our Galaxy. The observed angular size of Sgr-A* is found to be the largest among thousands of AGN observed over the sky; we discuss possible reasons of this strange result. Excluding extragalactic radio sources with significant scattering, we find that angular size of opaque cores in AGN scales typically as {nu}^-1^ confirming predictions of a conical synchrotron jet model with equipartition.
