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— Images and long-slit spectra of NGC 7094 and Abell 43 taken from the SPM Kinematic Catalogue of Galactic Planetary Nebulae, http://kincatpn.astrosen.unam.mx/.
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We present the first morpho-kinematical analysis of the planetary nebulae Kn
61 and Pa 5 and explore the nature of their central stars. Our analysis is
based on high resolution and medium resolution spectroscopic observations, deep
narrow-band imaging, and integral photometry. This material allows us to
identify the morphological components and stu...
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Citations
... A deep image from the Gemini North telescope is given by De Marco et al. (2015). The = 18.24 central star was studied spectroscopically by García-Díaz et al. (2014) and De Marco et al. (2015), and assigned a PG 1159 spectral type. Neither study obtained spectra at wavelengths short enough to cover the O doublet; to our knowledge, we are the first to detect it in emission. ...
... Neither study obtained spectra at wavelengths short enough to cover the O doublet; to our knowledge, we are the first to detect it in emission. García-Díaz et al. (2014) reported photometric variability of the central star, with a peak-to-peak amplitude of ∼0.02 mag and a period of 5.7 ± 0.4 days. Because Kn 61 lies in the field in Cygnus that was monitored by the Kepler mission, De Marco et al. (2015) were able to analyze the extensive Kepler photometry. ...
We report initial results from an ongoing spectroscopic survey of central stars of faint planetary nebulae (PNe), obtained with the Low-Resolution Spectrograph on the Hobby-Eberly Telescope. The six PN nuclei (PNNi) discussed here all have strong emission at the O VI 3811-3834 A doublet, indicative of very high temperatures. Five of them--the nuclei of Ou 2, Kn 61, Kn 15, Abell 72, and Kn 130--belong to the hydrogen-deficient PG 1159 class, showing a strong absorption feature of He II and C IV at 4650-4690 A. Based on exploratory comparisons with synthetic model-atmosphere spectra, and the presence of Ne VIII emission lines, we estimate them to have effective temperatures of order 170,000 K. The central star of Kn 15 has a Wolf-Rayet-like spectrum, with strong and broad emission lines of He II, C IV, N V, and O V-VI. We classify it [WO2], but we note that the N V 4604-4620 A emission doublet is extremely strong, indicating a relatively high nitrogen abundance. Several of the emission lines in Kn 15 vary in equivalent width by factors as large as 1.5 among our four observations from 2019 to 2022, implying significant variations in the stellar mass-loss rate. We encourage spectroscopic monitoring. Follow-up high-time-resolution photometry of these stars would be of interest, given the large fraction of pulsating variables seen among PG 1159 and [WO] PNNi.
... Kronberger et al. 2012;De Marco et al. 2015). García-Díaz et al. (2014) compared mediumresolution optical spectra of the CSPN Kn 61 with spectra published by Werner et al. (2014) and found a particularly close resemblance of the CSPN Kn 61 to SDSS 075415.12 + 085232.18, ...
Stellar post asymptotic giant branch (post-AGB) evolution can be completely altered by a final thermal pulse (FTP) which may occur when the star is still leaving the AGB (AFTP), at the departure from the AGB at still constant luminosity (late TP, LTP) or after the entry to the white-dwarf cooling sequence (very late TP, VLTP). Then convection mixes the He-rich material with the H-rich envelope. According to stellar evolution models the result is a star with a surface composition of $\mathrm{H}\approx \, 20$ per cent by mass (AFTP), ≈ 1 per cent (LTP), or (almost) no H (VLTP). Since FTP stars exhibit intershell material at their surface, spectral analyses establish constraints for AGB nucleosynthesis and stellar evolution. We performed a spectral analysis of the so-called hybrid PG 1159-type central stars (CS) of the planetary nebulae Abell 43 and NGC 7094 by means of non-local thermodynamical equilibrium models. We confirm the previously determined effective temperatures of $\mbox{$T_\mathrm{eff}$}\, = 115\, 000\pm 5\, 000 \, \mathrm{K}$ and determine surface gravities of $\log\,(g\,/\,(\mathrm{cm}\,\mathrm{s}^{-2} )) = 5.6\pm 0.1$ for both. From a comparison with AFTP evolutionary tracks, we derive stellar masses of $0.57^{+0.07}_{-0.04}$ M⊙ and determine the abundances of H, He, and metals up to Xe. Both CS are likely AFTP stars with a surface H mass fraction of 0.25 ± 0.03 and 0.15 ± 0.03, respectively, and an Fe deficiency indicating subsolar initial metallicities. The light metals show typical PG 1159-type abundances and the elemental composition is in good agreement with predictions from AFTP evolutionary models. However, the expansion ages do not agree with evolution time-scales expected from the AFTP scenario and alternatives should be explored.
... C0 and C1 channels hold the visual range filters (observations reported in this paper were taken with the r and i filters), C2 and C3 channels contain the near-infrared filters, and H2RG (HAWAII-2RG) are teledyne mercury-cadmium-telluride detectors. shown here (see also García-Díaz et al. 2014;Tapia et al. 2014;Ricci et al. 2015). Observations are executed in an automated queue mode (Watson et al. 2012) if no gamma-ray burst events are ongoing. ...
As part of our multi-observatory, multifilter campaign, we present r–i color observations of 82 near-Earth objects (NEOs) obtained with the reionization and transients infrared camera (RATIR) instrument on the 1.5 m robotic telescope at the San Pedro Martir’s National Observatory in Mexico. Our project is particularly focused on rapid-response observations of small (≲850 m) NEOs. The rapid response and the use of spectrophotometry allows us to constrain the taxonomic classification of NEOs with high efficiency. Here we present the methodology of our observations and our result, suggesting that the ratio of C-type to S-type asteroids in a size range of ∼30–850 m is 1.1, which is in accordance with our previous results. We also find that 10% of all NEOs in our sample are neither C- nor S-type asteroids
... Two long period binaries with periods of 1100 days and > 1800 days were discovered by Van Winckel et al. (2014), for PN G052.7+50.7 and LoTr 5. The PN IPHASXJ211420.0+434136 (Ou 5) gained a binary companion with a period of 8.4 h (Corradi et al. 2014b), and Kn 61 has a possible binary companion, with a period of 5.7 days (García-Díaz et al. 2014): its nebula is hydrogen deficient. NGC 2392 may have a 0.12 d companion, from radial velocity variations (Prinja & Urbaneja 2014); the star shows a strongly variable wind. ...
Planetary nebulae had a double anniversary in 2014, 250 year since their
discovery and 150 year since the correct spectroscopic identification. This
paper gives an overview of planetary nebula research published in 2014. Topics
include surveys, central stars, abundances, morphologies, magnetic fields,
stellar population and galactic dynamics. An important continuing controversy
is the discrepancy between recombination-line and forbidden-line abundances. A
new controversy is the relation between symbiotic stars and [WC] stars. PN of
the year is undoubtedly CRL 618, with papers on its binary symbiotic/[WC]
nucleus, rapid stellar evolution, expanding jets and magnetic fields.
... To these we add the PN Pa 5, for which the central star shows a wide He II 5412Å absorption line and the resolved nebula shows a narrow He II 5412Å emission line (García-Díaz et al. 2014). The minimum in the broad absorption line is 4 × 10 −17 erg s −1 cm −2Å−1 below the continuum, and the total absorbed flux is 10 −15 erg s −1 cm −2 . ...
We account for recent observations of the binary system at the center of the
bipolar planetary nebula Henize 2-428 by the presence of one degenerate core
with a low-mass main sequence companion, rather than by two degenerate objects.
We argue that the variability of the He II 5412A spectral line can be accounted
for by a time-varying broad absorption line from the central star on top of
which there is a time-varying narrow emission line from the compact nebula. The
two (almost) symmetric broad minima in the light curve are attributed to tidal
distortion caused by a companion. We find problems in the recently proposed and
competing explanation of two equal-mass degenerate objects that supposedly will
eventually merge, possibly leading to a SN Ia. We conclude that Henize 2-428
cannot be claimed yet to support the double-degenerate scenario for Type Ia
supernovae.
We report initial results from an ongoing spectroscopic survey of central stars of faint planetary nebulae (PNe), obtained with the Low-Resolution Spectrograph on the Hobby-Eberly Telescope. The six PN nuclei (PNNi) discussed here all have strong emission at the O vi 3811–3834 Å doublet, indicative of very high temperatures. Five of them—the nuclei of Ou 2, Kn 61, Kn 15, Abell 72, and Kn 130—belong to the hydrogen-deficient PG 1159 class, showing a strong absorption feature of He ii and C iv at 4650–4690 Å. Based on exploratory comparisons with synthetic model-atmosphere spectra, and the presence of Ne viii emission lines, we estimate them to have effective temperatures of order 170,000 K. The central star of Kn 15 has a Wolf-Rayet-like spectrum, with strong and broad emission lines of He ii, C iv, N v, and O v-vi. We classify it [WO2], but we note that the N v 4604–4620 Å emission doublet is extremely strong, indicating a relatively high nitrogen abundance. Several of the emission lines in Kn 15 vary in equivalent width by factors as large as 1.5 among our four observations from 2019 to 2022, implying significant variations in the stellar mass-loss rate. We encourage spectroscopic monitoring. Follow-up high-time-resolution photometry of these stars would be of interest, given the large fraction of pulsating variables seen among PG 1159 and [WO] PNNi.
Planetary nebulae represent a potential late stage of stellar evolution, however, their central stars (CSPNe) are relatively faint and, therefore, pertinent information is available for merely < 20% of the Galactic sample. Consequently, the literature was surveyed to construct a new catalogue of 620 CSPNe featuring important spectral classifications and information. The catalogue supersedes the existing iteration by 25% and includes physical parameters such as luminosity, surface gravity, temperature, magnitude estimates, and references for published spectra. The marked statistical improvement enabled the following pertinent conclusions to be determined: the H-rich/H-poor ratio is 2:1, there is a deficiency of CSPNe with types [WC 5-6], and nearly 80% of binary central stars belong to the H-rich group. The last finding suggests that evolutionary scenarios leading to the formation of binary central stars interfere with the conditions required for the formation of H-poor CSPN. Approximately 50% of the sample with derived values of log L ⋆ , log T eff , and log g , exhibit masses and ages consistent with single stellar evolutionary models. The implication is that single stars are indeed able to form planetary nebulae. Moreover, it is shown that H-poor CSPNe are formed by higher mass progenitors. The catalogue is available through the Vizier database.
Six planetary nebulae (PN) are known in the Kepler space telescope field of view, three of which are newly identified. Of the five central stars of PN with useful Kepler data, one, J193110888+4324577, is the first short-period, post-common envelope binary exhibiting relativistic beaming effects.
A second, the central star of the newly identified PN Pa 5, has a rare O(He) spectral type and a periodic variability consistent
with an evolved companion, where the orbital axis is almost aligned with the line of sight. The third PN, NGC 6826, has a
fast rotating central star, something that can only be achieved in a merger. Fourth, the central star of the newly identified
PN Kn 61, has a PG1159 spectral type and a mysterious semi-periodic light variability which we conjecture to be related to
the interplay of binarity with a stellar wind. Finally, the central star of the circular PN A61 does not appear to have a
photometric variability above 2 mmag. With the possible exception of the variability of Kn 61, all other variability behaviour,
would not easily have been detected from the ground. We conclude, based on very low numbers, that there may be many more close
binary or close binary products to be discovered with ultra-high-precision photometry. With a larger number of high-precision
photometric observations, we will be able to determine how much higher than the currently known 15 per cent, the short-period
binary fraction for central stars of PN is likely to be.
