- ID:
- ivo://CDS.VizieR/J/AJ/153/140
- Title:
- The kinematics of the C II {lambda}6578 line in PNe
- Short Name:
- J/AJ/153/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic observations of the C II {lambda}6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir. We study the kinematics of the C II {lambda}6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C II {lambda}6578 line are not those expected if this line arises from the recombination of C^2+^ ions or the fluorescence of C^+^ ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in H{alpha} line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/L75
- Title:
- The short period binary CSPN of M 3-1
- Short Name:
- J/MNRAS/482/L75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of a 3h5m orbital-period binary star at the heart of the planetary nebula M 3-1 - the shortest period photometrically variable central star known and second only to V458 Vul, in general. Combined modelling of light and radial velocity curves reveals both components to be close to Roche lobe filling, strongly indicating that the central star will rapidly evolve to become a cataclysmic variable, perhaps experiencing a similar evolution to V458 Vul resulting in a nova eruption before the planetary nebula has fully dissipated. While the short orbital period and near Roche lobe filling natures of both components make the central binary of M 3-1 an important test case with which to constrain the formation processes of cataclysmic variables, novae, and perhaps even supernovae type Ia.
- ID:
- ivo://CDS.VizieR/J/PASP/106/745
- Title:
- The Spectrum of IC 418
- Short Name:
- J/PASP/106/745
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A detailed high spectral resolution study of the spectrum of IC 418 is made for the region 3650{AA} to 10050{AA}, using the Hamilton echelle spectrograph of Lick Observatory, and of the UV spectral region with archival International Ultraviolet Explorer (IUE) data.
- ID:
- ivo://CDS.VizieR/J/PAZh/32/737
- Title:
- UBV light curve and spectroscopy of StHa62
- Short Name:
- J/PAZh/32/737
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric observations of HD 51585 (OY Gem), a B[e] star with an infrared excess and a candidate for protoplanetary nebulae, obtained with a 60-cm telescope at the Crimean Station of Sternberg Astronomical Institute in 1992-2005 are presented. The star exhibited rapid irregular brightness variations with amplitudes from 0.1mag in the V band to 0.2mag in the U band within the observing season as well as slow systematic variations. with a quasi-period of ~2800-days. Low-resolution spectroscopy performed in 1994-2005 has revealed significant variability of the Balmer and Paschen hydrogen emission lines as well as the HeI and OI lines. Equivalent widths are given for the HI, HeI, OI, and FeII lines. Correlation has been found between the star's photometric variability and the hydrogen line intensities.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/30
- Title:
- UBV photometry of IRAS 18062+2410
- Short Name:
- J/PAZh/25/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photometric and spectroscopic observations of IRAS 18062+2410 = V886 Her, a candidate for protoplanetary objects, in 1996-1997 are presented. The star exhibits rapid light variations with an amplitude up to 0.3mag in V. A high-resolution spectrum of IRAS shows absorption lines of H, HeI, OI, FeII, SiII, NaI and other species, including [OII], [NII], and [FeII] that belong to the stellar envelope.
- ID:
- ivo://CDS.VizieR/J/A+A/470/317
- Title:
- UV spectra of the central star of Sh 2-216
- Short Name:
- J/A+A/470/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a comprehensive spectral analysis of LS V +46 21 in order to compare its photospheric properties to theoretical predictions from stellar evolution theory as well as from diffusion calculations. LS V +46 21 is the DAO-type central star of the planetary nebula Sh 2-216. High-resolution, high-S/N ultraviolet observations obtained with FUSE and STIS aboard the HST as well as the optical spectrum have been analyzed in order to determine the photospheric parameters and the spectroscopic distance. We performed a detailed spectral analysis of the ultraviolet and optical spectrum by means of state-of-the-art NLTE model-atmosphere techniques. From the NIV-NV, OIV-OVI, SiIV-SiV, and FeV-FeVII ionization equilibria, we determined an effective temperature of 95+/-2kK with high precision. The surface gravity is logg=6.9+/-0.2. An unexplained discrepancy appears between the spectroscopic distance d=224^+46^_-58_pc and the parallax distance d=129^+6^_-5_pc of LS V +46 21. For the first time, we have identified Mg IV and Ar VI absorption lines in the spectrum of a hydrogen-rich central star and determined the Mg and Ar abundances as well as the individual abundances of iron-group elements (Cr, Mn, Fe, Co, and Ni). With the realistic treatment of metal opacities up to the iron group in the model-atmosphere calculations, the so-called Balmer-line problem (found in models that neglect metal-line blanketing) vanishes. Spectral analysis by means of NLTE model atmospheres has presently arrived at a high level of sophistication, which is now hampered largely by the lack of reliable atomic data and accurate line-broadening tables. Strong efforts should be made to improve upon this situation.
- ID:
- ivo://CDS.VizieR/J/A+A/287/591
- Title:
- UV Variations in spectrum of Abell 35 c.star
- Short Name:
- J/A+A/287/591
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/2586
- Title:
- UWISH2 extended H2 emission line sources
- Short Name:
- J/MNRAS/454/2586
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the extended source catalogue for the UKIRT Wide Field Infrared Survey for H2 (UWISH2). The survey is unbiased along the inner Galactic Plane from l~357{deg} to l~65{deg} and |b|<=1.5{deg} and covers 209deg^2^. A further 42.0 and 35.5deg^2^ of high dust column density regions have been targeted in Cygnus and Auriga. We have identified 33200 individual extended H_2_ features. They have been classified to be associated with about 700 groups of jets and outflows, 284 individual (candidate) planetary nebulae, 30 supernova remnants and about 1300 photodissociation regions. We find a clear decline of star formation activity (traced by H_2_ emission from jets and photodissociation regions) with increasing distance from the Galactic Centre. About 60 percent of the detected candidate planetary nebulae have no known counterpart and 25 percent of all supernova remnants have detectable H_2_ emission associated with them.
- ID:
- ivo://CDS.VizieR/J/AJ/159/21
- Title:
- V and Rc light curves of medium-bright PPNe
- Short Name:
- J/AJ/159/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 10 years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F-G spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation periods of IRAS04296+3429 (71 days), 06530-0213 (80 days), and 23304+6147 (84 days). A secondary period was found for each, with a period ratio P_2_/P_1_ of 0.9. The light variations are small, 0.1-0.2mag. These are similar to values found in other PPNe. The other two are found to be giant stars. IRAS09296+1159 pulsates with a period of only 47 days but reaches pulsational light variations of 0.5mag. Supplemental spectroscopy reveals the spectrum of a CH carbon star. IRAS08359-1644 is a G1III star that does not display pulsational variability; rather, it shows nonperiodic decreases of brightness of up to 0.5mag over this 10 year interval. These drops in brightness are reminiscent of the light curves of R Corona Borealis variables, but with much smaller decreases in brightness and are likely due to transient dust obscuration. Its spectral energy distribution is very similar to that of the unusual oxygen-rich giant star HDE233517, which possesses mid-infrared hydrocarbon emission features. These two non-PPNe turn out to be members of the rare group of giant stars with large mid-infrared excesses due to dust, objects which presumably have interesting evolutionary histories.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/1042
- Title:
- Variability in C-rich proto-PNe.
- Short Name:
- J/ApJ/709/1042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of ~150 days for the coolest (G8) to 35-40 days for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-asymptotic giant branch (post-AGB) star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200K), detached dust shells and published models imply that intensive mass loss ended 400-2000 years ago.
