- ID:
- ivo://CDS.VizieR/J/A+A/648/A93
- Title:
- 4 post-AGB stars datacubes
- Short Name:
- J/A+A/648/A93
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- There is a class of binary post-AGB stars with a remarkable near-infrared excess that are surrounded by Keplerian or quasi-Keplerian disks and extended outflows composed of gas escaping from the disk. The Keplerian dynamics had been well identified in four cases, namely the Red Rectangle, AC Her, IW Car, and IRAS 08544-4431. In these objects, the mass of the outflow represents ~10% of the nebular mass, the disk being the dominant component of the nebula. We aim to study the presence of rotating disks in sources of the same class in which the outflow seems to be the dominant component. We present interferometric NOEMA maps of ^12^CO and ^13^CO J=2-1 in 89 Her and ^12^CO J=2-1 in AC Her, IRAS 19125+0343, and R Sct. Several properties of the nebula are obtained from the data and model fitting, including the structure, density, and temperature distributions, as well as the dynamics. We also discuss the uncertainties on the derived values. The presence of an expanding component in AC Her is doubtful, but thanks to new maps and models, we estimate an upper limit to the mass of this outflow of <=3x10^-5^M^{sun}_, that is, the mass of the outflow is <=5% of the total nebular mass. For 89 Her, we find a total nebular mass of 1.4x10^-2^M_{sun}_, of which ~50% comes from an hourglass-shaped extended outflow. In the case of IRAS 19125+0343, the nebular mass is 1.1x10^-2^M_{sun}_, where the outflow contributes ~70% of the total mass. The nebular mass of R Sct is 3.2x10^-2^M_{sun}_, of which ~75% corresponds to a very extended outflow that surrounds the disk. Our results for IRAS 19125+0343 and R Sct lead us to introduce a new subclass of binary post-AGB stars, for which the outflow is the dominant component of the nebula. Moreover, the outflow mass fraction found in AC Her is smaller than those found in other disk-dominated binary post-AGB stars. 89 Her would represent an intermediate case between both subclasses.
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- ID:
- ivo://CDS.VizieR/J/A+A/479/155
- Title:
- Proper motions of Galactic Planetary Nebulae
- Short Name:
- J/A+A/479/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- More than 1500 Galactic planetary nebulae (PNe) are known but only a tiny fraction of them have measured proper motions. To date, the largest set of proper motion (PM) data for PNe is the one by Cudworth (1974AJ.....79.1384C), which includes 62 objects 25 of which have PM with significance better than 3{sigma}. With our new compilation of 234 PNe we enlarge - compared to Cudworth's 25 - by almost an order of magnitude the number of PNe and central stars (CSs) with reliably measured proper motion (i.e. with significance better than 3{sigma} in at least one component) and confirm some previous measurements. We have used all-sky astrometric catalogues available via the Vizier database to collect proper motion information for a sample of objects selected from the catalogue of PNe positions of Kerber et al. (2003, Cat. <J/A+A/408/1029>).
- ID:
- ivo://CDS.VizieR/J/A+A/593/A29
- Title:
- Properties of galactic PNe central stars
- Short Name:
- J/A+A/593/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained multi-wavelength observations of compact Galactic planetary nebulae (PNe) to probe post-asymptotic giant branch (AGB) evolution from the onset of nebular ejection. We analyze new observations from Hubble Space Telescope to derive the masses and evolutionary status of their central stars (CSs) in order to better understand the relationship between the CS properties and those of the surrounding nebulae. We work with HST/WFC3 images of 51 targets obtained in a snapshot survey (GO-11657). The high spatial resolution of HST allows us to resolve these compact PNe and distinguish the CS emission from that of their surrounding PNe. The targets were imaged through the filters F200LP, F350LP, and F814W from which we derive Johnson V and I magnitudes. We derive CS bolometric luminosities and effective temperatures using the Zanstra technique, from a combination of HST photometry and ground-based spectroscopic data. We present new unique photometric measurements of 50 CSs, and derived effective temperatures and luminosities for most of them.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A164
- Title:
- Protoplanetary nebulae and young PN CO spectra
- Short Name:
- J/A+A/649/A164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fast outflows and their interaction with slow shells (generally known as the fossil circumstellar envelope of asymptotic giant branch stars) play an important role in the structure and kinematics of protoplanetary and planetary nebulae (pPNe, PNe). To properly study their effects within these objects, we also need to observe the intermediate-temperature gas, which is only detectable in the far-infrared (FIR) and submillimetre (submm) transitions. We study the physical conditions of the outflows presented in a number of pPNe and PNe, with a focus on their temperature and excitation states. We carried out Herschel/HIFI observations in the submm lines of 12CO in nine pPNe and nine PNe and complemented them with low-J CO spectra obtained with the IRAM 30m telescope and taken from the literature. The spectral resolution of HIFI allows us to identify and measure the different nebular components in the line profiles. The comparison with large velocity gradient (LVG) model predictions was used to estimate the physical conditions of the warm gas in the nebulae, such as excitation conditions, temperature, and density. We found high kinetic temperatures for the fast winds of pPNe, typically reaching between 75K and 200K. In contrast, the high-velocity gas in the sampled PNe is colder, with characteristic temperatures between 25K and 75K, and it is found in a lower excitation state. We interpret this correlation of the kinetic temperature and excitation state of fast outflows with the amount of time elapsed since their acceleration (probably driven by shocks) as a consequence of the cooling that occurred during the pPN phase.
- ID:
- ivo://CDS.VizieR/J/A+A/373/1032
- Title:
- Radio emission from planetary nebulae
- Short Name:
- J/A+A/373/1032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analysed the radio fluxes for 264 planetary nebulae for which reliable measurements of fluxes at 1.4 and 5 GHz, and of nebular diameters are available. For many of the investigated nebulae, the optical thickness is important, especially at 1.4 GHz. Simple models like the one specified only by a single optical thickness or spherical, constant density shells do not account satisfactorily for the observations. Also an r^-2^ density distribution is ruled out. A reasonable representation of the observations can be obtained by a two-component model having regions of two different values of optical thickness. We show that the nebular diameters smaller than 10" are uncertain, particularly if they come from photographic plates or Gaussian fitting to the radio profile. While determining the interstellar extinction from an optical to radio flux ratio, caution should be paid regarding optical thickness effects in the radio. We have developed a method for estimating the value of self absorption. At 1.4 GHz self absorption of the flux is usually important and can exceed a factor of 10. At 5 GHz self absorption is negligible for most of the objects, although in some cases it can reach a factor of 2. The Galactic bulge planetary nebulae when used to calibrate the Shklovsky method give a mean nebular mass of 0.14M_{sun}_. The statistical uncertainty of the Shklovsky distances is smaller than a factor of 1.5.
- ID:
- ivo://CDS.VizieR/J/ApJS/159/282
- Title:
- 315 radio identified planetary nebulae
- Short Name:
- J/ApJS/159/282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 1.4GHz NRAO VLA Sky Survey (NVSS, Cat. <VIII/65>) images and source catalog, we identified 315 radio sources stronger than ~2.5mJy among over 1000 recently discovered planetary nebulae north of J2000 declination {delta}=-40{deg}. Two-thirds of these radio sources are weaker than 10mJy at 1.4GHz. This result is a uniform supplement to the previous NVSS radio identification of known PNe and a large homogeneous sample including over 1000 PNe with NVSS sources is obtained. By examining the radio properties of PNe, it is found that most of the planetary nebulae detected at both 1.4 and 5.0GHz are optically thick at {lambda}=20cm.
- ID:
- ivo://CDS.VizieR/J/A+A/274/895
- Title:
- Radio observations of South. PN Candidates
- Short Name:
- J/A+A/274/895
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS sources having IR colours typical of planetary nebulae and located outside the Galactic bulge were observed in the radio continuum at 6cm with the Australian Compact Array (ACA). 18 new planetary nebulae were discovered among 89 candidates. The observations were performed in March and April 1991.
- ID:
- ivo://CDS.VizieR/J/A+A/476/1019
- Title:
- RMS survey of southern candidate massive YSOs
- Short Name:
- J/A+A/476/1019
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey is an ongoing effort to return a large, well-selected sample of massive young stellar objects (MYSOs) within our Galaxy. 2000 candidates have been colour-selected from the Mid-course Space Experiment (MSX) point source catalogue (PSC). A series of ground-based follow-up observations are being undertaken in order to remove contaminant objects (ultra-compact HII (UCHII) regions, planetary nebulae (PN), evolved stars), and to begin characterising these MYSOs. As a part of these follow-up observations, high resolution (~1") mid-IR imaging aids the identification of contaminant objects which are resolved (UCHII regions, PN) as opposed to those which are unresolved (YSOs, evolved stars) as well as identifying YSOs near UCHII regions and other multiple sources. We present 10.4{mu}m imaging observations for 346 candidate MYSOs in the RMS survey in the Southern Hemisphere, primarily outside the region covered by the GLIMPSE Spitzer Legacy Survey. These were obtained using TIMMI2 on the ESO 3.6m telescope in La Silla, Chile. Our photometric accuracy is of order 0.05Jy, and our astrometric accuracy is 0.8", which is an improvement over the nominal 2" accuracy of the MSX PSC.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A46
- Title:
- Simulated IR spectra of PN Hubble 12
- Short Name:
- J/A+A/655/A46
- Date:
- 10 Mar 2022 07:09:39
- Publisher:
- CDS
- Description:
- We present a visible-infrared imaging study of young planetary nebula (PN) Hubble 12 (Hb 12; PN G111.8-02.8) obtained with Hubble Space Telescope (HST) archival data and our own Canada-France-Hawaii Telescope (CFHT) measurements. Deep HST and CFHT observations of this nebula reveal three pairs of bipolar structures and an arc-shaped filament near the western waist of Hb 12. The existence of nested bipolar lobes together with the presence of H2 knots suggests that these structures originated from several mass-ejection events during the pre-PN phase. To understand the intrinsic structures of Hb 12, a three-dimensional model enabling the visualisation of this PN at various orientations was constructed. The modelling results show that Hb 12 may resemble other nested hourglass nebulae, such as Hen 2-320 and M 2-9, suggesting that this type of PN may be common and the morphologies of PNs are not so diverse as is shown by their visual appearances. The infrared spectra show that this PN has a mixed chemistry. We discuss the possible material that may cause the unidentified infrared emissions. The analyses of the infrared spectra and the spectral energy distribution suggest the existence of a cool companion in the nucleus of this object.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/185
- Title:
- SiO masers in OH/IR stars, proto-PN and PN
- Short Name:
- J/A+AS/127/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a search for SiO masers towards a sample of 126 objects including OH/IR stars, proto-planetary and planetary nebulae. All objects are classified as oxygen-rich, and most of them are associated with OH or H_2_O masers. SiO masers were found only in variable objects like the OH/IR stars and a few objects classified as proto-planetary nebulae, but with variable central stars that may be part of binary systems. In one object, OH 15.7+0.8, which appears to be varying irregularly and most likely recently left the AGB, an SiO maser was tentatively detected. Thus, we conclude that variability and SiO maser emission are closely linked, and that SiO masers disappear very soon after a star has reached the end of the AGB, when pulsation and mass loss cease.
