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Start Over Subject planetary nebulae
91. Galactic PNe abundances
ID:
ivo://CDS.VizieR/J/MNRAS/349/793
Title:
Galactic PNe abundances
Short Name:
J/MNRAS/349/793
Date:
21 Oct 2021
Publisher:
CDS
Description:
New determinations of chemical abundances for He, N, O, Ne, Ar and S are derived for all galactic planetary nebulae (PNe) so far observed with a relatively high accuracy, in an effort to overcome differences in these quantities obtained over the years by different authors using different procedures.
92. Galactic PNe statistical distance scale
ID:
ivo://CDS.VizieR/J/ApJS/98/659
Title:
Galactic PNe statistical distance scale
Short Name:
J/ApJS/98/659
Date:
21 Oct 2021
Publisher:
CDS
Description:
A statistical distance scale is proposed. It is based on the correlation between the ionized mass and the radius and the correlation between the radio continuum surface brightness temperature and the nebular radius. The proposed statistical distance scale is an average of the two distances obtained using the correlations. These correlations, calibrated on the 132 planetary nebulae with well-determined individual distances by Zhang, can reproduce not only the average distance of a sample of Galactic Bulge planetary nebulae exactly at the distance to the Galactic center, but also the expected gaussian distribution of their distances around the Galactic center. This new distance scale is applied to 647 Galactic planetary nebulae. It is estimated that this distance scale can be accurate on average to 35%-50%. Our statistical distance scale is in good agreement with the one recently proposed by Van de Steene and Zijlstra
93. H{alpha} emission objects in the southern Milky Way
ID:
ivo://CDS.VizieR/III/277
Title:
H{alpha} emission objects in the southern Milky Way
Short Name:
III/277
Date:
21 Oct 2021
Publisher:
CDS
Description:
The stars reported in James Wray's PhD thesis result from photographic plates taken by Karl Henize in South Africa during 1949-1951 covering the Southern Galactic plane to about 10{deg} latitude. Accurate positions of the stars studied in the PhD thesis were recovered by B. Skiff, see details in the "intro.txt" file.
94. H{alpha} fluxes of Galactic planetary nebulae
ID:
ivo://CDS.VizieR/J/MNRAS/431/2
Title:
H{alpha} fluxes of Galactic planetary nebulae
Short Name:
J/MNRAS/431/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of new integrated H{alpha} fluxes for 1258 Galactic planetary nebulae (PNe), with the majority, totalling 1234, measured from the Southern H{alpha} Sky Survey Atlas (SHASSA) and/or the Virginia Tech Spectral-line Survey (VTSS). Aperture photometry on the continuum-subtracted digital images was performed to extract H{alpha}+[NII] fluxes in the case of SHASSA, and H{alpha} fluxes from VTSS. The [NII] contribution was then deconvolved from the SHASSA flux using spectrophotometric data taken from the literature or derived by us. Comparison with previous work shows that the flux scale presented here has no significant zero-point error. Our catalogue is the largest compilation of homogeneously derived PN fluxes in any waveband yet measured, and will be an important legacy and fresh benchmark for the community. Amongst its many applications, it can be used to determine statistical distances for these PNe, determine new absolute magnitudes for delineating the faint end of the PN luminosity function, provide baseline data for photoionization and hydrodynamical modelling, and allow better estimates of Zanstra temperatures for PN central stars with accurate optical photometry. We also provide total H{alpha} fluxes for another 75 objects which were formerly classified as PNe, as well as independent reddening determinations for ~270 PNe, derived from a comparison of our H{alpha} data with the best literature H{beta} fluxes. In an appendix, we list corrected H{alpha} fluxes for 49 PNe taken from the literature, including 24 PNe not detected on SHASSA or VTSS, re-calibrated to a common zero-point.
95. He, C, N and O abundances in planetary nebulae
ID:
ivo://CDS.VizieR/J/PAZh/35/574
Title:
He, C, N and O abundances in planetary nebulae
Short Name:
J/PAZh/35/574
Date:
21 Oct 2021
Publisher:
CDS
Description:
The He, C, N, and O abundances in more than 120 planetary nebulae (PNe) of our Galaxy and the Magellanic Clouds have been redetermined by analyzing new PNe observations. The characteristics of PNe obtained by modeling their spectra have been used to compile a new catalog of parameters for Galactic and extragalactic PNe, which is accessible at http://www.astro.spbu.ru/staff/afk/GalChemEvol.html. The errors in the parameters of PNe and their elemental abundances related to inaccuracies in the observational data have been analyzed. The He abundance is determined with an accuracy of 0.06dex, while the errors in the C, N, and O abundances are 0.1-0.2dex. Taking into account the inaccuracies in the corrections for the ionization stages of the elements whose lines are absent in the PNe spectra increases the errors in the He abundance to 0.1dex and in the C, N, and O abundances to 0.2-0.3dex. The elemental abundances in PNe of various Galactic subsystems and the Magellanic Clouds have been analyzed. This analysis suggests that the Galactic bulge objects are similar to type II PNe in Peimbert's classification, whose progenitor stars belong to the thin-disk population with ages of at least 4-6Gyr. A similarity between the elemental abundances in PNe of the Magellanic Clouds and the Galactic halo has been established.
96. HeII4686 line intensities of PN
ID:
ivo://CDS.VizieR/J/A+AS/106/559
Title:
HeII4686 line intensities of PN
Short Name:
J/A+AS/106/559
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have compiled the intensities of the HeII 4686 lines measured in Galactic planetary nebulae. We present a few observational diagrams related to this parameter, and discuss them with the help of theoretical diagrams obtained from simple model planetary nebulae surrounding evolving central stars of various masses. We determine the hydrogen and helium Zanstra temperature for all the objects with accurate enough data. We argue that, for Galactic planetary nebulae as a whole, the main cause for the Zanstra discrepancy is leakage of stellar ionizing photons from the nebulae.
97. Hen 2-155 and Hen 2-161 photometry and spectroscopy
ID:
ivo://CDS.VizieR/J/A+A/580/A19
Title:
Hen 2-155 and Hen 2-161 photometry and spectroscopy
Short Name:
J/A+A/580/A19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of Hen 2-155 and Hen 2-161, two planetary nebulae which bear striking morphological similarities to other planetary nebulae known to host close-binary central stars. Both central stars are revealed to be photometric variables while spectroscopic observations confirm that Hen 2-155 is host to a double-eclipsing, post-common-envelope system with an orbital period of 3h 33m making it one of the shortest period binary central stars known. The observations of Hen 2-161 are found to be consistent with a post-common-envelope binary of period ~1-day.
98. Hen 2-260 emission line fluxes
ID:
ivo://CDS.VizieR/J/A+A/567/A15
Title:
Hen 2-260 emission line fluxes
Short Name:
J/A+A/567/A15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analysed the planetary nebula Hen 2-260 using optical spectroscopy and photometry. We compared our observations with the literature data in order to search for evolutionary changes. We also searched for photometric variability of the central star. Hen 2-260 was observed with the SAAO 1.0m telescope (photometry) and the SALT telescope (low resolution spectroscopy). We also used archive high resolution Very Large Telescope spectra and Hubble Space Telescope imaging. The nebular line fluxes were modelled with the Cloudy photoionization code in order to derive the stellar and nebular parameters. The planetary nebula shows a complex structure and possibly a bipolar outflow. The nebula is relatively dense and young. The central star is just starting O^+^ ionization (Teff~30000K). Comparison of our observations with literature data indicates a 50% increase of the [OIII] 5007{AA} line flux between 2001 and 2012. We interpret it as the result of the progression of the ionization of O^+^. The central star evolves to higher temperatures at a rate of 45+/-7K/yr. The heating rate is consistent with post-AGB evolutionary tracks for a final mass of 0.626^+0.003^_-0.005_M_{sun}_ or 0.645+/-0.008M_{sun}_ for two different sets of tracks from literature. The photometric monitoring of Hen 2-260 revealed non-periodic variations on a timescale of hours or days. There is no direct indication for central star binarity in the spectrum, nor for a strong stellar wind. The variability may be caused by pulsations of the star. The temperature evolution of the central star can be traced using spectroscopic observations of the surrounding planetary nebula spanning a timescale of roughly a decade. This allows us for precise determination of the stellar mass, since the pace of the temperature evolution depends critically on the core mass. The method is independent on the absolute age of the nebula. The kinematical age of the nebula is consistent with the age obtained from the evolutionary track. The final mass of the central star is close to the peak of the mass distribution for central stars of planetary nebulae found in other studies. The object belongs to a group of young central stars of planetary nebulae showing photometric variability.
99. High-dispersion spectrum of the PN DdDm 1
ID:
ivo://CDS.VizieR/J/ApJ/705/509
Title:
High-dispersion spectrum of the PN DdDm 1
Short Name:
J/ApJ/705/509
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the High Dispersion Spectrograph (HDS) at the Subaru Telescope, we secured the high-resolution line spectra in the 3600-7500{AA} wavelength range of the Galactic halo planetary nebula DdDm 1. We also analyzed the Hubble Space Telescope Faint Object Spectrograph data in the 1200-6730{AA} wavelength range. The diagnostic results indicate the electron temperatures of T_{epsilon}_~11000-14000K and the electron number densities of N_{epsilon}_~2000-10500cm^-3^. In spite of high gaseous temperatures, we have not detected high excitation lines, e.g., HeII. We derived abundance based on the ionic concentration of permitted and forbidden lines and the photoionization model. A comparison of the ionic concentrations from forbidden lines to recombination lines shows the abundance discrepancy between them. We tested various possibilities, e.g., temperature fluctuation and high-density blob components, to explain the discrepancy. The high-density components or density fluctuation might be partly responsible for the discrepancy. DdDm 1 shows a low carbon abundance that corresponds to metal-poor stars, [Fe/H]<=-1. Assuming a distance of 10kpc to DdDm 1, theoretical models suggest that the central star has T_eff_~39000K and L~2000-3000L_{sun}_. The relatively high gas temperatures appear to be caused by very low heavy elemental abundances or insufficient coolants in the shell gas. Its progenitor, born in an extremely carbon-poor environment as an initial mass of about 0.9M_{sun}_, had probably experienced only the first dredge-up.
100. Hubble Space Telescope Heritage Press Release Images
ID:
ivo://mast.stsci/siap/heritage
Title:
Hubble Space Telescope Heritage Press Release Images
Short Name:
HST.heritage
Date:
23 Jul 2020 19:38:59
Publisher:
Space Telescope Science Institute Archive
Description:
WFPC2 and ACS images used to create the Heritage project color composite press releases. The data has been expertly prepared, significantly beyond the standard pipeline processing. This usually involves careful image registration, combination, and cleaning via drizzling, making it ready for further scientific analysis and educational use. These data will typically be made available at the time of the associated press release.