Halo Planetary Nebulae Research Articles

Seimei/KOOLS-IFU mapping of the gas and dust distributions in Galactic PNe: Unveiling the origin and evolution of the Galactic halo PN H4-1

Abstract H4-1 is a planetary nebula (PN) located in the Galactic halo, and is notably carbon-rich and one of the most metal-deficient PNe in the Milky Way. To unveil its progenitor evolution through accurate measurement of the gas mass, we conducted a comprehensive investigation of H4-1, using the newly obtained Seimei/KOOLS-IFU spectra and multiwavelength spectro-photometry data. The emission-line images generated from the KOOLS-IFU data cube successfully resolve the ellipsoidal nebula and the equatorial flattened disk that are frequently seen in bipolar PNe evolved from massive progenitors. By a fully data-driven method, we directly derived the seven elemental abundances, the gas-to-dust mass ratio, and the gas and dust masses based on our own distance scale. By comparing the observed quantities with both the photoionization model and the binary nucleosynthesis model, we conclude that the progenitors of initial masses of 1.87 M$_{\odot }$ and 0.82 M$_{\odot }$ are second-generation stars formed ∼4 Gyr after the Big Bang that have undergone mass transfers and a binary merger, and have ultimately evolved into a PN showing unique chemical abundances. Our binary model successfully reproduces the observed abundances and also explains the evolutionary time scale of H4-1.

J-PLUS: Tools to identify compact planetary nebulae in the Javalambre and southern photometric local Universe surveys

Context. From the approximately 3500 planetary nebulae (PNe) discovered in our Galaxy, only 14 are known to be members of the Galactic halo. Nevertheless, a systematic search for halo PNe has never been performed. Aims. In this study, we present new photometric diagnostic tools to identify compact PNe in the Galactic halo by making use of the novel 12-filter system projects, Javalambre Photometric Local Universe Survey (J-PLUS) and Southern-Photometric Local Universe Survey (S-PLUS). Methods. We reconstructed the Isaac Newton Telescope Photometric Hα Survey of the Northern Galactic Plane diagnostic diagram and propose four new ones using (i) the J-PLUS and S-PLUS synthetic photometry for a grid of photo-ionisation models of halo PNe, (ii) several observed halo PNe, as well as (iii) a number of other emission-line objects that resemble PNe. All colour–colour diagnostic diagrams are validated using two known halo PNe observed by J-PLUS during the scientific verification phase and the first data release (DR1) of S-PLUS and the DR1 of J-PLUS. Results. By applying our criteria to the DR1s (~1190 deg2), we identified one PN candidate. However, optical follow-up spectroscopy proved it to be a H II region belonging to the UGC 5272 galaxy. Here, we also discuss the PN and two H II galaxies recovered by these selection criteria. Finally, the cross-matching with the most updated PNe catalogue (HASH) helped us to highlight the potential of these surveys, since we recover all the known PNe in the observed area. Conclusions. The tools here proposed to identify PNe and separate them from their emission-line contaminants proved to be very efficient thanks to the combination of many colours, even when applied – like in the present work – to an automatic photometric search that is limited to compact PNe.

The spatial structure of the Galaxy subsystems as it looks from an analysis of the system of galactic planetary nebulae

We recalculated the distance to 554 galactic Planetary Nebulae (PNe) using the relation between the ionized mass of the nebula μ and the optical thickness parameter τ obtained by Akimkin et al. [1]. We classified these nebulae according to the Peimbert [9] types modified by Quireza et al. [11]. The obtained by us distances to galactic PNe were used to obtain the scale heights h for different subsystem of the Milky Way. Next values if h were estimated: h = 208 ± 10 pc for thin disk objects, h = 600 ± 54 pc for thick disk ones, and h = 1378 ± 180 pc for halo PNe.

Chemical Abundances of Planetary Nebulae in the Substructures of M31. II. The Extended Sample and a Comparison Study with the Outer-disk Group*

Abstract We report deep spectroscopy of 10 planetary nebulae (PNe) in the Andromeda Galaxy (M31) using the 10.4 m Gran Telescopio Canarias (GTC). Our targets reside in different regions of M31, including halo streams and the dwarf satellite M32, and kinematically deviate from the extended disk. The temperature-sensitive [O iii] λ4363 line is observed in all PNe. For four PNe, the GTC spectra extend beyond 1 μm, enabling the explicit detection of the [S iii] λ6312 and λλ9069, 9531 lines and thus determination of the [S iii] temperature. Abundance ratios are derived and generally consistent with AGB model predictions. Our PNe probably all evolved from low-mass (<2 M ☉) stars, as analyzed with the most up-to-date post-AGB evolutionary models, and their main-sequence ages are mostly ∼2–5 Gyr. Compared to the underlying, smooth, metal-poor halo of M31, our targets are uniformly metal rich ([O/H] ≳ −0.4), and seem to resemble the younger population in the stream. We thus speculate that our halo PNe formed in the Giant Stream’s progenitor through extended star formation. Alternatively, they might have formed from the same metal-rich gas as did the outer-disk PNe but were displaced into their present locations as a result of galactic interactions. These interpretations are, although speculative, qualitatively in line with the current picture, as inferred from previous wide-field photometric surveys, that M31's halo is the result of complex interactions and merger processes. The behavior of the N/O of the combined sample of the outer-disk and our halo/substructure PNe signifies that hot bottom burning might actually occur at <3 M ☉ but careful assessment is needed.

The kinematics of the nebular shells around low mass progenitors of PNe with low metallicity

AbstractIn the past few years we provided strong observational support for theoretical studies regarding the internal kinematics of Planetary Nebulae (PNe). A total of 257 objects segregated by different galactic populations were analized. Based upon spatially-resolved, long-slit, echelle spectroscopy drawn from the San Pedro Mártir Kinematic Catalogue of PNe†, we characterized the kinematics of PNe shells measuring their global expansion velocities. We present here a brief summary of these observational results, with a focus on our most recent study of about 26 PNe with low metallicity that appear to derive from progenitor stars of the lowest masses (including the halo PNe population). Low expansion velocities were found for these nebulae, less than 20 km s−1, which are most likely associated with a weak central star wind driving the kinematics of the nebular shell in this particular population.

Observations of the planetary nebula RWT 152 with OSIRIS/GTC

RWT 152 is one of the few known planetary nebulae with an sdO central star. We present subarcsecond red tunable filter Halpha imaging and intermediate-resolution, long-slit spectroscopy of RWT 152 obtained with OSIRIS/GTC with the goal of analyzing its properties. The Halpha image reveals a bipolar nebula with a bright equatorial region and multiple bubbles in the main lobes. A faint circular halo surrounds the main nebula. The nebular spectra reveal a very low-excitation nebula with weak emission lines from H^+, He^+, and double-ionized metals, and absence of emission lines from neutral and single-ionized metals, except for an extremely faint [NII]6584 emission line. These spectra may be explained if RWT 152 is a density-bounded planetary nebula. Low nebular chemical abundances of S, O, Ar, N, and Ne are obtained in RWT 152, which, together with the derived high peculiar velocity ($\sim$ 92-131 km s$^{-1}$), indicate that this object is a halo planetary nebula. The available data are consistent with RWT 152 evolving from a low-mass progenitor ($\sim$ 1 M$_{\odot}$) formed in a metal-poor environment.

Searching for planetary nebulae at the Galactic halo via J-PAS

AbstractThe Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) is a narrow-band imaging, very wide field cosmological survey. It will last 5 years and will observe 8500 sq. deg. of the sky. There will be 54 contiguous narrow-band filters of 145Å FWHM, from 3,500 to 10,000Å. Two broad-band filters will be added at the extremes, UV and IR, plus the 3–g, r, and i– SDSS filters. Thus, J-PAS can be an important tool to search for new planetary nebulae (PNe) at the halo, increasing their numbers, because only 14 of them have been convincingly identified in the literature. Halo PNe are able to reveal precious information for the study of stellar evolution and the early chemical conditions of the Galaxy. The characteristic low continuum and intense emission lines of PNe make them good objects to be searched by J-PAS. Though covering a significantly smaller sky area, data from the ALHAMBRA survey were used to test our J-PAS strategy to search for PNe. Our first results are shown in this contribution.

Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

AbstractThe diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60–90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

CHEMICAL ABUNDANCES AND DUST IN THE HALO PLANETARY NEBULA K648 IN M15: ITS ORIGIN AND EVOLUTION BASED ON AN ANALYSIS OF MULTIWAVELENGTH DATA

We report an investigation of the extremely metal-poor and C-rich planetary nebula (PN) K648 in the globular cluster M15 using the UV to far-IR data obtained using the Subaru, HST, FUSE, Spitzer, and Herschel. We determined the nebular abundances of ten elements. The enhancement of F ([F/H]=+0.96) is comparable to that of the halo PN BoBn1. The central stellar abundances of seven elements are determined. The stellar C/O ratio is similar to the nebular C/O ratios from recombination line and from collisionally excited line (CEL) within error, and the stellar Ne/O ratio is also close to the nebular CEL Ne/O ratio. We found evidence of carbonaceous dust grains and molecules including Class B 6-9 um and 11.3 um polycyclic aromatic hydrocarbons and the broad 11 um feature. The profiles of these bands are similar to those of the C-rich halo PNe H4-1 and BoBn1. Based on the theoretical model, we determined the physical conditions of the gas and dust and their masses, i.e., 0.048 Msun and 4.95x10^{-7} Msun, respectively. The observed chemical abundances and gas mass are in good agreement with an asymptotic giant branch nucleosynthesis model prediction for stars with an initial 1.25 Msun plus a 2.0x10^{-3} Msun partial mixing zone (PMZ) and stars with an initial mass of 1.5 Msun without a PMZ. The core-mass of the central star is approximately 0.61-0.63 Msun. K648 is therefore likely to have evolved from a progenitor that experienced coalescence or tidal disruption during the early stages of evolution, and became a ~1.25-1.5 Msun blue straggler.

CHEMICAL ABUNDANCES IN THE EXTREMELY CARBON-RICH AND XENON-RICH HALO PLANETARY NEBULA H4-1

We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H]-2) halo planetary nebula H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III]5846 A line in H4-1 and determination of its elemental abundance ([Xe/H]>+0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a ~2.0 Msun single star model with initially r-process element rich ([r/Fe]=+2.0 dex). The observed Xe abundance would be a product of the r-process in primordial SNe. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with two types of carbon-enhanced metal-poor stars (CEMP), CEMP-r/s and CEMP-no stars. The progenitor of H4-1 is a presumably binary formed in an r-process rich environment.

The ionization state of the halo planetary nebula NGC 2438

AbstractNGC 2438 is a classical multiple shell or halo planetary nebula (PN). Its central star and the main nebula are well studied. Also it was target of various hydrodynamic simulations (Corradi et al. 2000). This initiated a discussion whether the haloes are mainly containing recombined gas (Schönberner et al. 2002), or if they are still ionized (Armsdorfer et al. 2003). An analysis of narrow-band images and long slit spectra at multiple slit positions was done to obtain a deeper look on morphological details and the properties of the outer shell and halo. For this work there was data available from ESO (direct imaging and long slit spectroscopy) and from SAAO (spectroscopic observations using a small slit, scanning over the whole nebula). Using temperature measurements from emission lines resulted in an electron temperature which clearly indicates a fully ionized stage. Additionally measurements of the electron density suggest a variation of the filling factor.

THE ORIGIN AND EVOLUTION OF THE HALO PN BoBn 1: FROM A VIEWPOINT OF CHEMICAL ABUNDANCES BASED ON MULTIWAVELENGTH SPECTRA

We have performed a comprehensive chemical abundance analysis of the extremely metal-poor ([Ar/H]<-2) halo planetary nebula (PN) BoBn 1 based on IUE archive data, Subaru/HDS spectra, VLT/UVES archive data, and Spitzer/IRS spectra. We have detected over 600 lines in total and calculated ionic and elemental abundances of 13 elements using detected optical recombination lines (ORLs) and collisionally excited lines (CELs). The estimations of C, N, O, and Ne abundances from the ORLs and Kr, Xe, and Ba from the CELs are done the first for this nebula, empirically and theoretically. The C, N, O, and Ne abundances from ORLs are systematically larger than those from CELs. The abundance discrepancies apart from O could be explained by a temperature fluctuation model, and that of O might be by a hydrogen deficient cold component model. We have detected 5 fluorine and several s-process elements. The amounts of [F/H], [Kr/H], and [Xe/H] suggest that BoBn 1 is the most F-rich among F detected PNe and is a heavy s-process element rich PN. We have confirmed dust in the nebula that is composed of amorphous carbon and PAHs with a total mass of 5.8 x 10^-6 Msun. The photo-ionization models built with non-LTE theoretical stellar atmospheres indicate that the progenitor was a 1-1.5 Msun star that would evolve into a white dwarf with an ~0.62 Msun core mass and ~0.09 Msun ionized nebula. The derived elemental abundances have been reviewed from the standpoint of theoretical nucleosynthesis models. It is likely that the elemental abundances except N could be explained either by a 1.5 Msun single star model or by a binary model composed of 0.75 Msun + 1.5 Msun stars. Careful examination implies that BoBn 1 has evolved from a 0.75 Msun + 1.5 Msun binary and experienced coalescence during the evolution to become a visible PN, similar to the other extremely metal-poor halo PN, K 648 in M 15.

HIGH-DISPERSION SPECTRUM OF THE HALO PLANETARY NEBULA DdDm 1

Using the High Dispersion Spectrograph (HDS) at the Subaru Telescope, we secured the high-resolution line spectra in the 3600-7500 A 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 A wavelength range. The diagnostic results indicate the electron temperatures of T {sub e}psilonapprox 11,000-14,000 K and the electron number densities of N {sub e}psilonapprox 2000-10,500 cm{sup -3}. In spite of high gaseous temperatures, we have not detected high excitation lines, e.g., He II. 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 10 kpc to DdDm 1, theoretical models suggest that the central star has T {sub eff}approx = 39,000 K and Lapprox = 2000-3000 L {sub sun}. The relatively high gas temperaturesmore » 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 0.9 M {sub sun}, had probably experienced only the first dredge-up.« less

A search for s-process elements in extremely metal-poor halo planetary nebulae

AbstractWe have performed deep high-dispersion spectroscopy to examine enhancement of s-process elements in the exremely metal-poor ([Ar/H]~−2.1) halo planetary nebulae H4-1 and BoBn1 using the 8.2-m Subaru telescope/High-Dispersion Spectrograph (HDS). We have detected several emission lines of s-process elements in H4-1 and BoBn1, and we have found that the enhancement of heavy s-process elements in these objects is comparable with that in s-process enhanced CEMP stars with [Fe/H]&gt;−2.5. The C- and N-rich abundances of H4-1 and BoBn1 might be explained by binary evolution models. We have detected 5 fluorine lines in BoBn1. The re-estimated F abundance using these lines is [F/H]=+1.4±0.1.

Detection of Fluorine in the Halo Planetary Nebula BoBn 1: Evidence for a Binary Progenitor Star

We have found the fluorine lines [F IV] ??3996.92, 4059.90 in the extremely metal-poor ([Ar/H] = ?2.10 ? 0.21) halo planetary nebula (PN) BoBn 1 in high-dispersion spectra from the 8.2 m VLT UVES archive. Chemical abundance analysis shows that the fluorine abundance is [F/H] = +1.06 ? 0.08, making BoBn 1 the most fluorine-enhanced and metal-poor PN among fluorine-detected PNe and providing new evidence that fluorine is enhanced by nucleosynthesis in low-mass metal-poor stars. A comparison with the abundances of carbon-enhanced metal-poor (CEMP) stars suggests that BoBn 1 shares their origin and evolution with CEMP- s stars such as HE 1305+0132. BoBn 1 might have evolved from a binary consisting of ~2 M? primary and ~0.8 M? secondary stars.

A Multiwavelength Analysis of the Halo Planetary Nebula DdDm‐1

We present new HST optical imagery as well as new UV and IR spectroscopic data obtained with the Hubble Space Telescope and Spitzer Space Telescope, respectively, of the halo planetary nebula DdDm-1. For the first time we present a resolved image of this object, which indicates that the morphology of DdDm-1 can be described as two orthogonal elliptical components in the central part surrounded by an extended halo. The extent of the emission is somewhat larger than was previously reported in the literature. We combine the spectral data with our own previously published optical measurements to derive nebular abundances of He, C, N, O, Ne, Si, S, Cl, Ar, and Fe. The metallicity, as gauged by oxygen, is found to be 0.60 dex below the solar value, confirming DdDm-1's status as a halo PN. In addition, we find that Si and Fe are markedly underabundant, suggesting their depletion onto dust. The very low C/O ratio suggests that the chemistry of the nebula should be consistent with an oxygen-rich environment. With regard to the unexpectedly low S abundance relative to O often seen in PNe, we find that the sulfur abundance of DdDm-1 is only slightly below the value expected based on the normal lockstep behavior between S and O observed in H II regions and blue compact galaxies. We performed a photoionization model analysis from which we inferred a central star effective temperature and luminosity of 55,000 K and 1000 L☉, respectively, implying an initial progenitor mass of <1 M☉. Finally, we report on a new radial velocity determination from echelle observations.

Expansion Velocities and Core Masses of Bright Planetary Nebulae in the Virgo Cluster

The line-of-sight velocities and [O III] 5007 A expansion velocities are measured for 11 planetary nebulae (PNs) in the Virgo Cluster core, at 15 Mpc distance, with the FLAMES spectrograph on the ESO VLT. These PNs are located about halfway between the two giant elliptical galaxies M87 and M86. From the [O III] 5007 A line profile widths, the average half-width at half-maximum expansion velocity for this sample of 11 PNs is HWHM = 16.5 km s−1 (rms = 2.6 km s−1). We use the PN subsample bound to M87 to remove the distance uncertainties and the resulting [O III] 5007 A luminosities to derive the central star masses. We find these masses to be at least 0.6 M☉ and obtain PN observable lifetimes tPN < 2000 yr, which imply that the bright PNs detected in the Virgo Cluster core are compact, high-density nebulae. We finally discuss several scenarios for explaining the high central star masses in these bright M87 halo PNs.

Identification of PN G232.0+05.7 as a new halo planetary nebula and of IRAS 19336-0400 as a new type III planetary nebula

Aims.We determined the nature and Peimbert type of two low-excitation planetary nebulae, PNG 232.0+05.7 and IRAS 19336-0400.

High Dispersion Spectroscopy of the PN K 648 in the Globular Cluster M 15

We present our recent results of the high dispersion spectroscopy of a Galactic halo planetary nebula, K 648, in the globular cluster M 15. The position-velocity diagrams of our spectra indicate the existence of collimated outflows in K 648. In the [N II in the central region of K648.

Endogenous oxygen in the extremely metal-poor planetary nebula PN G135.9+55.9

It is shown that, in contrast to recent claims, oxygen (and helium) may not be extraordinarily underabundant in the new galactic halo planetary nebula (GHPN) PN G135.9+55.9 (hereafter PN G135). Determining elemental abundances in hot, highly ionized objects such as PN G135 depends critically on a proper description of the collisional excitation of the hydrogen Balmer lines, the departure from Case B recombination of hydrogen, the underlying stellar absorption lines, the shape of the primary continuum and the ionization equilibrium of highly ionized species of both oxygen and neon. Conversely, PN G135 provides unique checks of atomic data in unusual conditions: the H  collision strengths obtained by Aggarwal et al. (1991) for 1s − n transitions (3 ≤ n ≤ 5) are too large, while those obtained by Anderson et al. (2002) are acceptable. Empirical collision strengths are presented for n > 5. Photoionization models of PN G135 that fit all available optical data can be demonstrated only for oxygen abundances 12 + log (O/H) > 7. 2( >1/30 solar) and values 0.6 dex larger are possible, depending on the assumed C/O abundance ratio. Plausible variations in the geometry of the nebula, the primary stellar continuum and the atomic data do not alter this conclusion. The C/O ratio is less than 10 by number and Ne/O is at most solar. A satisfactory model for PN G135 can be obtained in which elemental abundances are nearly the same as those of a new detailed model for K 648, the prototypical GHPN in the old globular cluster M 15 (with 12 + log (O/H) = 7.58 ∼ 1/13 solar), although C/O may be smaller. Nonetheless, given the paucity of argon and iron in the nebula, PN G135 is likely to be a more extreme Population II object than K 648, reinforcing the idea of an endogenous origin for part of the oxygen in very metal-poor PNe. Assuming a standard H-burning post-Asymptotic Giant Branch evolution, timescale and spectroscopic considerations lead to an optimal solution, in which the distance to PN G135 is 8 kpc, the effective temperature of the nucleus slightly less than 1.3 × 10 5 K, its luminosity 1.4 × 10 37 erg s −1 , its mass 0.59 M� , the age of the ionized shell 10 4 yrs, the ionized mass 0.05 Mand the abundances by number (H:He:C:O:Ne) = (10 6 :81 500:90:30:4.5), with C/H being rather an upper limit and O/ Ha nd Ne/H uncertain by ±0.3 and ±0.1 dex respectively. Line intensities that could be used as diagnostics of the nebular elemental abundances are provided. Detailed imaging together with ultraviolet and very deep far-red spectra of PN G135 will be essential to definitely narrow the range of acceptable parameters and help us decide whether this exceptional PN is so oxygen-poor as to possibly influence current views on stellar evolution.