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- ID:
- ivo://CDS.VizieR/J/other/RMxAA/37.115
- Title:
- Optical coordinates of southern PNe
- Short Name:
- J/other/RMxAA/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A homogeneous set of new measurements of nearly all (995 out of 1007) objects from the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Cat. <V/100>) or in the first supplement of this catalogue in the area covered by the DENIS survey (<B/denis>) ({delta}<+2{deg}) is given here. A list of 24 new and 27 wrong cross-identifications with sources in the IRAS PSC catalogue and some confusion in the literature is listed as well.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A63
- Title:
- Optical spectra of new low-excitation PNs
- Short Name:
- J/A+A/563/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present mid-resolution spectroscopic observations of four new planetary nebula (PN) candidates selected from the INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS) and Deep Sky Hunter (DSH) catalogues. The PN status of these objects was confirmed by mid-resolution spectra. Based on the locations of these objects in the log(H-alpha/[NII]) versus log (H-alpha/[SII]) diagnostic diagram, these sources are evolved low- excitation PNs.
- ID:
- ivo://CDS.VizieR/J/A+A/458/173
- Title:
- Optical spectroscopy of 253 IRAS sources
- Short Name:
- J/A+A/458/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the optical spectral properties of a sample of stars showing far infrared colours similar to those of well-known planetary nebulae. The large majority of them were unidentified sources or poorly known in the literature at the time when this spectroscopic survey started, some 15 years ago. We present low-resolution optical spectroscopy, finding charts and improved astrometric coordinates of a sample of 253 IRAS sources.
- ID:
- ivo://CDS.VizieR/J/A+A/404/545
- Title:
- Optical spectrum of M 2-24
- Short Name:
- J/A+A/404/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained medium-resolution, deep optical long-slit spectra of the bulge planetary nebula (PN) M 2-24. The spectrum covers the wavelength range from 3610-7330{AA}. Over two hundred emission lines have been detected. The spectra show a variety of optical recombination lines (ORLs) from C, N, O and Ne ions. The diagnostic diagram shows significant density and temperature variations across the nebula. Our analysis suggests that the nebula has a dense central emission core. The nebula was thus studied by dividing it into two regions: 1) an high ionization region characterized by an electron temperature of T_e_=16300K and a density of logN_e_(cm^-3^)=6.3; and 2) a low ionization region represented by T_e_=11400K and logN_e_(cm^-3^)=3.7. A large number of ORLs from C, N, O and Ne ions have been used to determine the abundances of these elements relative to hydrogen. In general, the resultant abundances are found to be higher than the corresponding values deduced from collisionally excited lines (CELs). This bulge PN is found to have large enhancements in two {alpha}-elements, magnesium and neon.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A48
- Title:
- 4 oxygen-rich evolved stars NH3 spectra
- Short Name:
- J/A+A/612/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The circumstellar ammonia (NH_3_) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH_3_ abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry. We would like to characterise the spatial distribution and excitation of NH_3_ in the oxygen-rich circumstellar envelopes (CSEs) of four diverse targets: IK Tau, VY CMa, OH 231.8+4.2, and IRC +10420. We observed NH_3_ emission from the ground state in the inversion transitions near 1.3cm with the Very Large Array (VLA) and submillimetre rotational transitions with the Heterodyne Instrument for the Far-Infrared (HIFI) aboard Herschel Space Observatory from all four targets. For IK Tau and VY CMa, we observed NH_3_ rovibrational absorption lines in 2 band near 10.5um with the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF).We also attempted to search for the rotational transition within the excited vibrational state (v_2_=1) near 2mm with the IRAM 30m Telescope. Non-LTE radiative transfer modelling, including radiative pumping to the vibrational state, was carried out to derive the radial distribution of NH_3_ in the CSEs of these targets. We detected NH_3_ inversion and rotational emission in all four targets. IK Tau and VY CMa show blueshifted absorption in the rovibrational spectra. We did not detect vibrationally excited rotational transition from IK Tau. Spatially resolved VLA images of IK Tau and IRC +10420 show clumpy emission structures; unresolved images of VY CMa and OH 231.8+4.2 indicate that the spatial-kinematic distribution of NH_3_ is similar to that of assorted molecules, such as SO and SO2, that exhibit localised and clumpy emission. Our modelling shows that the NH_3_ abundance relative to molecular hydrogen is generally of the order of 10^-7^, which is a few times lower than previous estimates that were made without considering radiative pumping and is at least ten times higher than that in the carbon-rich CSE of IRC +10216. NH_3_ in OH 231.8+4.2 and IRC +10420 is found to emit in gas denser than the ambient medium. Incidentally, we also derived a new period of IK Tau from its V-band light curve. NH_3_ is again detected in very high abundance in evolved stars, especially the oxygen-rich ones. Its emission mainly arises from localised spatial-kinematic structures that are probably denser than the ambient gas. Circumstellar shocks in the accelerated wind may contribute to the production of NH_3_. Future mid-infrared spectroscopy and radio imaging studies are necessary to constrain the radii and physical conditions of the formation regions of NH_3_.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/121
- Title:
- Photometric survey of planetary nebulae in M31
- Short Name:
- J/ApJ/792/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search the Hubble Space Telescope (HST) Advanced Camera for Surveys and Wide Field Camera 3 broadband imaging data from the Panchromatic Hubble Andromeda Treasury (PHAT) survey to identify detections of cataloged planetary nebulae (PNs). Of the 711 PNs currently in the literature within the PHAT footprint, we find 467 detected in the broadband. For these 467, we are able to refine their astrometric accuracy from ~0.3'' to 0.05''. Using the resolution of the HST, we are able to show that 152 objects currently in the catalogs are definitively not PNs, and we show that 32 objects thought to be extended in ground-based images are actually point-like and therefore good PN candidates. We also find one PN candidate that is marginally resolved. If this is a PN, it is up to 0.7 pc in diameter. With our new photometric data, we develop a method of measuring the level of excitation in individual PNs by comparing broadband and narrowband imaging and describe the effects of excitation on a PN's photometric signature. Using the photometric properties of the known PNs in the PHAT catalogs, we search for more PNs, but do not find any new candidates, suggesting that ground-based emission-line surveys are complete in the PHAT footprint to F475W =~ 24.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/133
- Title:
- 1889-2015 photometry of Stingray nebula
- Short Name:
- J/ApJ/812/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980s ionization event by declining from B=10.30 in 1889 to B=10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20mag/yr, reaching B=14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994 to 2015, the V-band light curve is almost entirely from the flux of two bright [OIII] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090mag/yr. This steady fading (also seen in the radio and infrared) has a timescale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/657/76
- Title:
- Planetary nebula candidates in 3 galaxies
- Short Name:
- J/ApJ/657/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an [OIII] {lambda}5007 survey for PNe in five galaxies that were hosts of well-observed SNe Ia: NGC 524, NGC 1316, NGC 1380, NGC 1448, and NGC 4526. The goals of this survey are to better quantify the zero point of the maximum magnitude-decline rate relation for SNe Ia and to validate the insensitivity of Type Ia luminosity to parent stellar population using the host galaxy Hubble type as a surrogate. We detected a total of 45 PN candidates in NGC 1316, 44 candidates in NGC 1380, and 94 candidates in NGC 4526.
- ID:
- ivo://CDS.VizieR/J/A+A/332/721
- Title:
- Planetary nebulae abundances
- Short Name:
- J/A+A/332/721
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long slit spectrophotometry of 13 bipolar planetary nebulae has been used to study their physical and chemical properties. In each nebula, one to seven different spatial regions have been considered in order to search for possible abundance variations through the nebulae. We obtained the following main results: - within the errors, the He, O, and N abundances are constant through all the nebulae. - the Ne, Ar, and S abundances are also constant, within the errors, but their face values have systematic increases toward the outer regions of the nebulae. These trends may be attributed to inaccuracies in the ionization correction factors, as predicted by Alexander & Balick (1997AJ....114..713A) for long-slit observations of extended PNe. The corresponding increase of the N abundance predicted by those authors is, however, generally not observed (with one exception). - The present sample contains some of the Galactic PNe with the highest He and N/O abundances known to date (M 3-2, He 2-111, NGC 6537). The highest He overabundances cannot by reproduced by any current model of AGB evolution. - Oxygen depletion is suggested for the nebulae with the highest N/O abundances, indicating that efficient ON cycle process has occurred in their progenitors.
