Halo Planetary Nebulae Research Articles

The kinematics of the most oxygen-poor planetary nebula PN G 135.9+55.9

PN G 135.9+55.9 is a compact, high excitation nebula that has been identified recently as the most oxygen-poor halo planetary nebula. Given its very peculiar characteristics and potential implications in the realms of stellar and Galactic evolution, additional data are needed to firmly establish its true nature and evolutionary history. Here we present the first long- slit, high spectral resolution observations of this object in the lines of H and Heii4686. The position-velocity data are shown to be compatible with the interpretation of PN G 135.9+55.9 being a halo planetary nebula. In both emission lines, we find the same two velocity components that characterize the kinematics as that of an expanding elliptical envelope. The kinematics is consistent with a prolate ellipsoidal model with axis ratio about 2:1, a radially decreasing emissivity distribution, a velocity distribution that is radial, and an expansion velocity of 30 km s 1 for the bulk of the material. To fit the observed line profiles, this model requires an asymmetric matter distribution, with the blue-shifted emission considerably stronger than the red-shifted emission. We find that the widths of the two velocity components are substantially wider than those expected due to thermal motions, but kinematic structure in the projected area covered by the slit appears to be sucient to explain the line widths. The present data also rule out the possible presence of an accretion disk in the system that could have been responsible for a fraction of the H flux, further supporting the planetary nebula nature of PN G 135.9+55.9.

Analysis of Internal Motions in the Halo Planetary Nebula H4‐1

ABSTRACTUp to now, 10 planetary nebulae have been regarded as halo planetary nebulae (halo PNe). We obtained low‐ and moderate‐dispersion spectra of the spatially resolved halo planetary nebula H4‐1 in the wavelength region of 3700–6800 Å with the Cassegrain Spectrograph of the 74 inch telescope. At moderate dispersions, we were able to observe [Oiii] λλ4959, 5007 and Hα of H4‐1 at several position angles (P.A.). We assumed that the widths of these emission‐line profiles were due to Doppler broadening and that these emission lines were composed of several Gaussian components. Multiple Gaussian deconvolution analysis of such emission lines indicated H4‐1 has broad wing components (∼600 km s−1) at P.A. 135° and 180°. We think H4‐1 has a “bipolar flow” between P.A. 135° and 180°. From low‐dispersion spectra, we confirm that H4‐1 is a metal‐poor PN. In spite of the lack of spatially resolved images at present, we believe that H4‐1 has a bipolar flow and that its axis is almost parallel to the line of sight, with a small inclination angle.

Analysis on Internal Motions of the Halo Planetray Nebula, H4-1

Up to now, ten planetary nebulae are regarded as halo planetary nebulae (halo PNe). We obtained low- and moderate-dispersion spectra of the spatially resolved halo planetary nebula H4-1 in the wavelength region of λλ3700-6800 Å with the Cassegrain Spectrograph of 74-inch telescope at Okayama Astronomical Observatory. In the moderate dispersion observation, we were able to obtain [O III] λλ4959,5007 and Hα of H4-1 at several position angles (P.A.). The image was spatially resolved and its apparent angluar size should be less than 10″.0.

Observations of [S [CSC]iv[/CSC]] 10.5 μm and [N[CLC]e[/CLC] [CSC]ii[/CSC]] 12.8 μm in Two Halo Planetary Nebulae: Implications for Chemical Self-Enrichment

We have detected the [S IV] 10.5 μm and [Ne II] 12.8 μm fine-structure lines in the halo population planetary nebula (PN) DdDm 1 and set upper limits on their intensities in the halo PN H4-1. We also present new measurements of optical lines from various ions of S, Ne, O, and H for DdDm 1, based on a high-dispersion spectrum covering the spectral range 3800 A to 1 μm. These nebulae have similar O/H abundances, (O/H) ~ 1 × 10-4, but S/H and Ne/H are about half an order of magnitude lower in H4-1 than in DdDm 1; thus H4-1 appears to belong to a more metal-poor population. This supports previous suggestions that PNe arising from metal-poor progenitor stars can have elevated oxygen abundances due to internal nucleosynthesis and convective dredge-up. It is generally accepted that high abundances of carbon in many PNe result from self-enrichment. To the extent that oxygen can also be affected, the use of nebular O/H values to infer the overall metallicity of a parent stellar population (for example, in external galaxies) may be suspect, particularly for low metallicities.

The Most Oxygen-Poor Planetary Nebula

PNG135.9+55.9 is a halo planetary nebula recently discovered among the objects from the Second Byurakan Survey. Based upon our first observations, a photoionization model analysis shows that the oxygen abundance in the nebula must be extremely low, probably 10-2–10-3 of the solar value. This finding has strong implications on our understanding of the formation of planetary nebulae, of mixing processes in the stellar progenitors and of the evolution of the Galactic halo.

Evidence for binarity in the bipolar planetary nebulae A 79, He 2-428 and M 1-91

We present low and high resolution long-slit spectra of three bipolar planetary nebulae (PNe) with bright central cores: A 79, He 2-428 and M 1-91. He 2-428 and M 1-91 have high density (from 103.3 to 106.5 cm-3) unresolved nebular cores that indicate that strong mass loss/exchange phenomena are occurring close to their central stars. An F0 star is found at the centre of symmetry of A 79; its reddening and distance are consistent with the association of the star with the nebula. The spectrum of the core of He 2-428 shows indications of the presence of a hot star with red excess emission, probably arising in a late-type companion. A 79 is one of the richest PNe in and , the abundances of M 1-91 are at the lower end of the range spanned by bipolar PNe, and He 2-428 shows very low abundances, similar to those measured for halo PNe. The extended nebulae of A 79 and He 2-428 have inclined equatorial rings expanding at a velocity of ~15 km s-1, with kinematical ages ≥104 yrs. The association of these aged, extended nebulae with a dense nebular core (He 2-428) or a relatively late type star (A 79) is interpreted as evidence for the binarity of their nuclei.

The mass of the Andromeda galaxy

ABSTRA C T This paper argues that the Milky Way galaxy is probably the largest member of the Local Group. The evidence comes from estimates of the total mass of the Andromeda galaxy (M31) derived from the three-dimensional positions and radial velocities of its satellite galaxies, as well as the projected positions and radial velocities of its distant globular clusters and planetary nebulae. The available data set comprises 10 satellite galaxies, 17 distant globular clusters and nine halo planetary nebulae with radial velocities. We find that the halo of Andromeda has a mass of ,12:3 118 26 10 11 M(; together with a scalelength of ,90 kpc and a predominantly isotropic velocity distribution. For comparison, our earlier estimate for the Milky Way halo is 19 136 217 10 11 M(: Although the error bars are admittedly large, this suggests that the total mass of M31 is probably less than that of the Milky Way .W e verify the robustness of our results to changes in the modelling assumptions and to errors caused by the small size and incompleteness of the data set. Our surprising claim can be checked in several ways in the near future. The numbers of satellite galaxies, planetary nebulae and globular clusters with radial velocities can be increased by ground-based spectroscopy, while the proper motions of the companion galaxies and the unresolved cores of the globular clusters can be measured using the astrometric satellites Space Interferometry Mission (SIM) and Global Astrometric Interferometer for Astrophysics (GAIA). Using 100 globular clusters at projected radii 20 & R & 50 kpc with both radial velocities and proper motions, it will be possible to estimate the mass within 50 kpc to an accuracy of ,20 per cent. Measuring the proper motions of the companion galaxies with SIM and GAIA will reduce the uncertainty in the total mass caused by the small size of the data set to ,22 per cent.

Is the Galactic Halo Planetary Nebula PN G243−37.1 an “O vi Sequence” Variable Object?

ABSTRACTArchival IUE spectra of the Galactic halo planetary nebula PN G243−37.1 have been reprocessed by the NEWSIPS routine. The new results show a much richer emission‐line spectrum than has previously been reported. Several C iii, C iv, O v, and possibly O vi features were detected. P Cygni line profiles could not be identified with certainty. The He ii λ1640 emission, which is the strongest line in the IUE spectrum and is likely a mixture of stellar and nebular origin, increased in intensity as did the stellar continuum level between observational epochs of 1988 and 1990, which suggests that the object is a variable planetary nebula. A very recent optical spectrum confirms the UV results and suggests that the object underwent a dramatic change, possibly as a result of an episodic mass‐loss event.

Chemical Abundances of Planetary Nebulae in the Sagittarius Dwarf Elliptical Galaxy

Spectrophotometry and imaging of the two planetary nebulae He2-436 and Wray16-423, recently discovered to be in the Sagittarius dwarf elliptical galaxy, are presented. Wray16-423 is a high excitation planetary nebula (PN) with a hot central star. In contrast He2-436 is a high density PN with a cooler central star and evidence of local dust, the extinction exceeding that for Wray16-423 by E(B-V)=0.28. The extinction to Wray16-423, (E(B-V)=0.14), is consistent with the extinction to the Sagittarius (Sgr) Dwarf. Both PN show Wolf-Rayet features in their spectra, although the lines are weak in Wray16-423. Images in [O III] and H-alpha+[N II], although affected by poor seeing, yield a diameter of 1.2'' for Wray16-423 after deconvolution; He~2-436 was unresolved. He2-436 has a luminosity about twice that of Wray16-423 and its size and high density suggest a younger PN. In order to reconcile the differing luminosity and nebular properties of the two PN with similar age progenitor stars, it is suggested that they are on He burning tracks The abundance pattern is very similar in both nebulae and shows an oxygen depletion of -0.4 dex with respect to the mean O abundance of Galactic PN and [O/H] = -0.6. The Sgr PN progenitor stars are representative of the higher metallicity tail of the Sgr population. The pattern of abundance depletion is similar to that in the only other PN in a dwarf galaxy companion of the Milky Way, that in Fornax, for which new spectra are presented. However the abundances are larger than for Galactic halo PN suggesting a later formation age. The O abundance of the Sgr galaxy deduced from its PN, shows similarities with that of dwarf ellipticals around M31, suggesting that this galaxy was a dwarf elliptical before its interaction with the Milky Way.

High velocity collimated flow in a Halo Planetary Nebula, H 4-1

H 4-1, PNG 049.3+88.1 (α = 12h59m27.6s, δ = +27° 38′14″, 2000), was one of well known halo Planetary Nebulae (PNe). During our program to study the expanding characteristics of PNe, the long-slit spectroscopic observations were made by the cassegrain spectrograph of the 74 inch telescope at the Okayama Astrophysical Observatory in March 1995.

A detailed abundance analysis of nine halo planetary nebulae

A detailed abundance analysis of nine halo planetary nebulae

HST FOS spectroscopy of M2-29 and DDDM-1

The halo planetary nebulae are of special interest insofar as the sample is very limited and they show a wide range of nebular chemical properties. We are interested in deriving their detailed nebular properties and to try to determine the characteristics of their progenitor stars. We selected M2-29 and DDDM-1 since they are the most deficient in Ar and S of their group. During HST Cycle 3 we obtained WFC1 direct imagery in Hα of them to derive information on their morphology and surface brightness for performing FOS spectroscopy.

LSIV -12 deg 111 - A candidate halo proto-planetary nebula

We report on multiwavelength observations of LSIV −12°111, which may be an emerging halo planetary nebula. This object was previously classified as a young emission-line B-type star, but a model atmosphere abundance analysis of high-resolution optical spectra has revealed it to be an evolved object, probably in the postasymptotic giant branch (AGB) evolutionary phase. The presence of an infrared excess and low-excitation nebular emission lines implies that the central star may just have started to photoionize the circumstellar material ejected during the AGB phase. In this paper we discuss the nebular and dust properties of LSIV −12°111 and redetermine some metal abundances for the central star

LSIV −12° 111 – A Newly Emerging Halo Planetary Nebula

We report on multi-wavelength observations of a young halo planetary nebula, LSIV −12° 111. This object was previously classified as an emission-line young B-type star but a model atmosphere abundance analysis of high resolution optical spectra revealed it to be an evolved object, probably in the post-asymptotic giant branch (post-AGB) evolutionary phase. The presence of an infrared excess and low excitation nebular emission lines implies that the central star may have just started to photoionize the remnant (AGB) circumstellar material. Here we discuss the nebular and dust properties of LSIV −12° 111 and re-determine some metal abundances for the central star. These results are used to constrain the evolutionary status of this unique halo planetary nebula.

Ultraviolet and Optical Spectra of Central Stars of Halo Planetary Nebulae

Optical and UV spectrophotometric data are analyzed for the central stars of the known Population II planetary nebulae. From this, we derive visual magnitudes, spectral classification, color temperatures, luminosities and masses of the objects. It is found that all the stars show absorption type spectrum and most of them have normal H and He photospheric abundances, the only possible exceptions are M 2–29 and GJJC-1 which seem to be H-deficient stars.

A grain-heated, dusty planetary nebula in M22

We have carried out detailed modeling of a halo planetary nebula located in the metal-poor globular cluster M22. Models of the far-infrared continuum emission observed by the IRAS satellite indicate that the total dust mass is ∼10 −3 M ⊙ , a large amount of dust when compared to the upper limit of 4×10 −3 M ⊙ to the total H and He mass. Photoelectric emission from dust grains heats the nebular gas to temperatures ∼10 4 K and accounts for the observed [O III] and [Ne III] emission. Our grain-heated nebular models predict a large, negative temperature gradient across the nebula.

THE HALO PLANETARY NEBULAE M 2-29 AND BB-1

ABSTRACT Spectrophotometric data for the two planetary nebulae are given and compared to the data for a well-understood type of planetary nebula (PN) for classification and measurements of abundances. M 2-29 and BB-1 were observed in the wavelength ranges of 3500-5000 and 6000-7500, and the visual calibrated spectra and emission-line fluxes are given along with previous UV data. A reddening correction is applied, and the physical conditions, ionic abundances, and total abundances are presented. Of particular note are the M-2-29 O/H ratio (determined to be the lowest of the planetary nebulae), the high concentrations of C, N, and Ne in BB-1, and the low abundances of Ar and S in BB-1. M 2-29 is theorized to belong to the Type-IV PN group which contains high abundances of Ar and S, and progenitor stars are concluded to be responsible for O and Ne excesses in planetary nebulae.

Investigations of DDDM 1; The Fourth Halo Planetary Nebula

Spectral (λλ 4100 - 7300 A) and photoelectric observations of DDDM 1 (61 + 41°1; δ1950 = +38°48′) were made in 1985–86 on Crimean Station of Sternberg State Institute. Photographic absolute H3 flux is found to be F(Hβ) = (3.0±0.57) 10−12 erg cm−2 s−1, angular radius φ = 1″.0±0″.5. Interstellar reddening E(B-V) for the object is found to be less than 0″.02. Integrated flux from central star and gaseous nebula was measured in UBV-filters V = 14m.71, B-V = 0m.12, U-B = −0m.9.

HD 46703 - A high-luminosity population II F-type star

view Abstract Citations (76) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS HD 46703 : a high-luminosity population II F-type star. Luck, R. E. ; Bond, H. E. Abstract It is pointed out that A- and F-type stars lying several magnitudes above the horizontal branch occur occasionally in globular clusters. The chemical compositions and other properties of these highly evolved stars are of considerable interest. The present investigation is concerned with HD 46703, which is believed to be another field analog of the Population II A- and F-type supergiants. A description of photometry and low-resolution spectroscopy is presented, and aspects of high-resolution spectroscopy are discussed, taking into account radial velocities and equivalent widths, lines of carbon and oxygen, and H-alpha emission, Chemical abundances and their determination are considered, giving attention to the method of analysis, the iron group and light metals, the s-process elements, carbon and oxygen abundances, and the relationship to halo planetary nebulae. The evolutionary status of HD 46703 is also studied. Publication: The Astrophysical Journal Pub Date: April 1984 DOI: 10.1086/161939 Bibcode: 1984ApJ...279..729L Keywords: A Stars; Abundance; F Stars; Globular Clusters; Stellar Luminosity; Stellar Spectrophotometry; Supergiant Stars; Balmer Series; H Alpha Line; Planetary Nebulae; Spectral Line Width; Stellar Evolution; Stellar Magnitude; Ubv Spectra; Astrophysics full text sources ADS | data products SIMBAD (1)

Sulfur abundances in three halo planetary nebulae

The intensities of the (SIII) lambda9532 lines have been measured for the first time in the three known extreme halo planetary nebulae. Improved measurements have also been made of the (SII) lambda6717+lambda6731 lines. The S/H abundance ratios are (4.7 +- 6.8) x 10/sup -7/ for 108-76/sup 0/1, (1.4 +- 1.1) x 10/sup -7/ for K648, and (1.6 +- 1.1) x 10/sup -7/ for 49+88/sup 0/1. The S abundance in 108-76/sup 0/1 is too uncertain to draw any conclusions except that it is less than a tenth solar. The S abundances in the other two are approximately 1/100 of those in disk planetary nebulae and the Sun, consistent with the low Ar abundances also found in the halo planetary nebulae and with the Fe deficiency in the stars in M15, of which K648 is a member. Since the O and Ne abundances in the halo nebulae cover a wide range (nearly solar to 1/50 solar), the implication is that either the abundances of these elements have been enhanced by nuclear reactions in the planetary progenitors of S and Ar were synthesized galactically at a slower rate than O or Ne. In either case, it appears that S, like Ar, may bemore » more representative of the true heavy-metal abundance in planetary nebulae than lighter elements like O and Ne.« less