Circumstellar Envelopes Of Carbon Stars Research Articles

Gas-phase preparation of the dibenzo[e,l]pyrene (C24H14) butterfly molecule via a phenyl radical-mediated ring annulation.

A high temperature phenyl-mediated addition-cyclization-dehydrogenation mechanism to form peri-fused polycyclic aromatic hydrocarbon (PAH) derivatives-illustrated through the formation of dibenzo[e,l]pyrene (C24H14)-is explored through a gas-phase reaction of the phenyl radical (C6H5˙) with triphenylene (C18H12) utilizing photoelectron photoion coincidence spectroscopy (PEPICO) combined with electronic structure calculations. Low-lying vibrational modes of dibenzo[e,l]pyrene exhibit out-of-plane bending and are easily populated in high temperature environments such as combustion flames and circumstellar envelopes of carbon stars, thus stressing dibenzo[e,l]pyrene as a strong target for far-IR astronomical surveys.

Gas phase synthesis of the C40 nano bowl C40H10

Nanobowls represent vital molecular building blocks of end-capped nanotubes and fullerenes detected in combustion systems and in deep space such as toward the planetary nebula TC-1, but their fundamental formation mechanisms have remained elusive. By merging molecular beam experiments with electronic structure calculations, we reveal a complex chain of reactions initiated through the gas-phase preparation of benzocorannulene (C24H12) via ring annulation of the corannulenyl radical (C20H9•) by vinylacetylene (C4H4) as identified isomer-selectively in situ via photoionization efficiency curves and photoion mass-selected threshold photoelectron spectra. In silico studies provided compelling evidence that the benzannulation mechanism can be expanded to pentabenzocorannulene (C40H20) followed by successive cyclodehydrogenation to the C40 nanobowl (C40H10) – a fundamental building block of buckminsterfullerene (C60). This high-temperature pathway opens up isomer-selective routes to nanobowls via resonantly stabilized free-radical intermediates and ring annulation in circumstellar envelopes of carbon stars and planetary nebulae as their descendants eventually altering our insights of the complex chemistry of carbon in our Galaxy.

Molecular structure and spectroscopic properties of two radicals of C4H2N: a DFT study.

The cyano propargyl radical (CH2C3N and HC3HCN) is important reaction intermediate in both combustion flames and extraterrestrial environments such as cold molecular clouds and circumstellar envelopes of carbon stars. The acquisition of spectroscopic constants and anharmonic effect facilitates a more in-depth study of this radical. However, the data available in the literature do not allow the precise predictions for it in the interstellar medium. In this work, complete spectroscopic parameters as well as anharmonic constants of two radicals of C4H2N have been evaluated by different DFT methods. The calculated results show that it is reasonable to study the molecular spectroscopic properties of C4H2N by wB97XD/6-311++G theoretical level. On this basis, the sextic centrifugal distortion constants, anharmonic constants, vibration-rotation interaction constants, and so on are predicted for the study of high-precision rovibrational spectrum. In addition, the relationship between the anharmonic effect and vibration mode of CH2C3N and HC3HCN and their infrared spectroscopic characteristics are discussed. The calculation of the anharmonic force fields and spectroscopy properties was performed using B3LYP, B3PW91, CAM-B3LYP, and wB97XD methods combined with the 6-311++G and aug-ccpVTZ basis sets, respectively, by the Gaussian16 program suite. The IR spectra were performed with Multiwfn3.8.

How to add a five-membered ring to polycyclic aromatic hydrocarbons (PAHs) - molecular mass growth of the 2-naphthyl radical (C10H7) to benzindenes (C13H10) as a case study.

The three-ring polycyclic aromatic hydrocarbons (PAHs) 3H-benz[e]indene (C13H10) and 1H-benz[f]indene (C13H10) along with their naphthalene-based isomers 2-(prop-2-yn-1-yl)naphthalene (C13H10), 2-(prop-1-yn-1-yl)naphthalene (C13H10), and 2-(propa-1,2-dien-1-yl)naphthalene (C13H10) were formed through a "directed synthesis"via a high temperature chemical micro reactor under combustion-like conditions (1300 ± 35 K) through the reactions of the 2-naphthyl isomer (C10H7˙) with allene (C3H4) and methylacetylene (C3H4). The isomer distributions were probed utilizing tunable vacuum ultraviolet radiation from the Advanced Light Source (ALS) by recording the photoionization efficiency curves at mass-to-charge of m/z = 166 (C13H10) and 167 (13CC12H10) of the products in a supersonic molecular beam. Complemented by electronic structure calculations, our study reveals critical mass growth processes via annulation of a five-membered ring from the reaction between aryl radicals and distinct C3H4 isomers at elevated temperatures as present in combustion processes and in circumstellar envelopes of carbon stars. The underlying reaction mechanisms proceed through the initial addition of the 2-naphthyl radical with its radical center to the π-electron density of the allene and methylacetylene reactants via entrance barriers between 8 and 14 kJ mol-1, followed by isomerization (hydrogen shifts, ring closure), and termination via atomic hydrogen losses accompanied by aromatization. The reaction mechanisms reflect the formation of indene - the prototype PAH carrying a single five- and a single six-membered ring - synthesized through the reaction of the phenyl radical (C6H5˙) with allene and methylacetylene. This leads us to predict that aryl radicals - upon reaction with allene/methylacetylene - may undergo molecular mass growth processes via ring annulation and de facto addition of a five-membered ring to form molecular building blocks essential to transit planar PAHs out of the plane.

Unravelling the sulphur chemistry of AGB stars

AbstractThere are clear differences in what sulphur molecules form in AGB circumstellar envelopes (CSEs) across chemical types. CS forms more readily in the CSEs of carbon stars, while SO and SO2 have only been detected towards oxygen-rich stars. However, we have also discovered differences in sulphur chemistry based on the density of the CSE, as traced by mass-loss rate divided by expansion velocity. For example, the radial distribution of SO is drastically different between AGB stars with lower and higher density CSEs. H2S can be found in high abundances towards higher density oxygen-rich stars, whereas SiS accounts for a significant portion of the circumstellar sulphur for higher density carbon stars.

Estimating the dust production rate of carbon stars in the Small Magellanic Cloud

We employ newly computed grids of spectra reprocessed by dust for estimating the total dust production rate (DPR) of carbon stars in the Small Magellanic Cloud (SMC). For the first time, the grids of spectra are computed as a function of the main stellar parameters, i.e. mass-loss rate, luminosity, effective temperature, current stellar mass and element abundances at the photosphere, following a consistent, physically grounded scheme of dust growth coupled with stationary wind outflow. The model accounts for the dust growth of various dust species formed in the circumstellar envelopes of carbon stars, such as carbon dust, silicon carbide and metallic iron. In particular, we employ some selected combinations of optical constants and grain sizes for carbon dust that have been shown to reproduce simultaneously the most relevant colour–colour diagrams in the SMC. By employing our grids of models, we fit the spectral energy distributions of ≈3100 carbon stars in the SMC, consistently deriving some important dust and stellar properties, i.e. luminosities, mass-loss rates, gas-to-dust ratios, expansion velocities and dust chemistry. We discuss these properties and we compare some of them with observations in the Galaxy and Large Magellanic Cloud. We compute the DPR of carbon stars in the SMC, finding that the estimates provided by our method can be significantly different, between a factor of ≈2–5, than the ones available in the literature. Our grids of models, including the spectra and other relevant dust and stellar quantities, are publicly available at http://starkey.astro.unipd.it/web/guest/dustymodels.

GAS PHASE SYNTHESIS OF (ISO)QUINOLINE AND ITS ROLE IN THE FORMATION OF NUCLEOBASES IN THE INTERSTELLAR MEDIUM

Nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) have been proposed to play a key role in the astrochemical evolution of the interstellar medium, yet the formation mechanisms of even their simplest prototypes—quinoline and isoquinoline—remain elusive. Here, we reveal a novel concept that under high temperature conditions representing circumstellar envelopes of carbon stars, (iso)quinoline can be synthesized via the reaction of pyridyl radicals with two acetylene molecules. The facile gas phase formation of (iso)quinoline in circumstellar envelopes defines a hitherto elusive reaction class synthesizing aromatic structures with embedded nitrogen atoms that are essential building blocks in contemporary biological-structural motifs. Once ejected from circumstellar shells and incorporated into icy interstellar grains in cold molecular clouds, these NPAHs can be functionalized by photo processing forming nucleobase-type structures as sampled in the Murchison meteorite.

AN EXPERIMENTAL AND THEORETICAL STUDY OF THE IONIZATION ENERGIES OF SiC2Hx(x= 0, 1, 2) ISOMERS

We present a combined experimental and theoretical study on the formation processes and ionization energies of small organo-silicon molecules of the formula SiC2Hx (x?= 0, 1, 2). These organic molecules are considered important benchmark systems in understanding the formation of silicon- and carbon-bearing grains in the outflow of carbon stars. The studies identify four distinct (hydrogenated) silicon-carbon molecules together with their ionization energies: c-SiC2 [9.75?? 0.10?eV; 9.83?? 0.05?eV], l-HCCSi [7.00?? 0.05?eV], c-SiC2H [7.27?? 0.05?eV], and c-SiC2H2 [9.05?? 0.05?eV; 8.96?? 0.05?eV] with numbers in italics depicting computed data. Implications of these results to the non-equilibrium chemistry in shocked regions of circumstellar envelopes of carbon stars are also discussed.

A crossed molecular beams study of the reaction of dicarbon molecules with benzene

We conducted the reaction of dicarbon molecules in their electronic ground, C 2 ( X 1 Σ g + ) , and first excited state, C 2(a 3Π u), with benzene, C 6H 6(X 1A 1g). The phenylethynyl radical (C 6H 5CC; X 2A′) and atomic hydrogen were inferred to be the reaction products under single collision conditions. The reactions were indirect via short-lived C 8H 6 intermediates which decomposed via atomic hydrogen elimination without exit barrier (singlet surface) and via a tight exit transition state (triplet surface). Our experiments suggest that the phenylethynyl radical can be likely formed via bimolecular reactions involving dicarbon molecules with benzene in extreme environments such as circumstellar envelopes of carbon stars, planetary nebulae, and combustion flames.

A Combined Experimental and Theoretical Study of the Reaction of Dicarbon (C2) with D1‐Acetylene (HCCD): Possible Mechanisms for Deuterium Enrichment in the Interstellar D1‐Butadiynyl Radical, CCCCD(X2Σ+)

The reaction of the dicarbon molecule (C2) with D1-acetylene (HCCD) was carried out under single-collision conditions in a crossed molecular beams machine to investigate deuterium enrichment processes in cold molecular clouds and in circumstellar envelopes of carbon stars. The experiments were merged with electronic structure calculations. Our combined experimental and theoretical studies suggest that this barrierless neutral-neutral reaction can induce a deuterium enrichment in the D1-1,3-butadiynyl radical (CCCCD) over a broad range of collision energies formally corresponding to temperatures from 10 to a few thousand kelvin as present in cold molecular clouds and circumstellar envelopes close to the photosphere, respectively. Generalized, each rapid, neutral-neutral reaction, which proceeds through indirect scattering dynamics via a reaction intermediate residing in a deep potential energy well, can induce a deuterium enrichment in cold molecular clouds (10 K) and evenat elevatedtemperatures of a few thousand K as present, for instance, in the envelope of the dying carbon star IRC +10216. These findings should trigger an astronomical survey of the D1-1,3-butadiynyl molecule in the circumstellar shells of IRC +10216. Subject headingg ISM: molecules — molecular processes

SiO in C-rich circumstellar envelopes of AGB stars: effects of non-LTE chemistry and grain adsorption

Aims.New SiO multi-transition millimetre line observations of a sample of carbon stars, including J = observations with the APEX telescope, are used to probe the role of non-equilibrium chemistry and the influence of grains in circumstellar envelopes of carbon stars.

Reaction dynamics of carbon-bearing radicals in circumstellar envelopes of carbon stars

Crossed molecular beams experiments on dicarbon molecules, C2(X1sigmag+/a3piu), with unsaturated hydrocarbons acetylene (C2H2(X1sigmag+), ethylene (C2H4(X1Ag)), methylacetylene (CH3CCH(X1A1)), and allene (H2CCCH2 (X1A1)) were carried out at 18 collision energies between 10.6 and 50.3 kJ mol(-1) utilizing a universal crossed beams machine to untangle the reaction dynamics forming hydrogen deficient hydrocarbon radicals in circumstellar envelopes of carbons stars and in cold molecular clouds. We find that all reactions proceed without the entrance barrier through indirect (complex forming) scattering dynamics. Each bimolecular collision is initiated by an addition of the dicarbon molecule to the pi bond of the unsaturated hydrocarbon molecule yielding initially acyclic (triplet) and three- or four-membered cyclic collision complexes (triplet and singlet surface). On the singlet surface, the cyclic structures isomerize to form eventually diacetylene (HCCCCH; C2/C2H2), butatriene (H2CCCCH2; C2/C2H4), methyldiacetylene (CH3CCCCH; C2/CH3CCH), and pentatetraene (H2CCCCCH2; C2/H2CCCH2) intermediates. The latter were found to decompose via atomic hydrogen loss yielding the buta-1,3-diynyl [C4H(X2sigma+) HCCCC], 1-butene-3-yne-2-yl [i-C4H3(X2A') H2CCCCH], penta-2,4-diynyl-1 [C5H3(X2B1) HCCCCCH2], and penta-1,4-diynyl-3 radical [C5H3(X2B1) HCCCHCCH] under single collision conditions. The underlying characteristics of these dicarbon versus atomic hydrogen replacement pathways (indirect scattering dynamics; no entrance barrier; isomerization barriers below the energy of the separated reactants; exoergic reactions) suggest the enormous potential of the dicarbon plus unsaturated hydrocarbon reaction class to form highly hydrogen-deficient carbonaceous molecules in cold molecular clouds and in circumstellar envelopes of carbon stars. The studies therefore present an important advancement in establishing a comprehensive database of reaction intermediates and products involved in bimolecular collisions of dicarbon molecules with unsaturated hydrocarbons which can be utilized in refined astrochemical models and also in future searches of hitherto unidentified interstellar molecules. Implications of these experiments to understand related combustion processes are also addressed.

A crossed beams study of the reaction of carbon atoms, C(3Pj), with vinyl cyanide, C2H3CN(X1A′)—investigating the formation of cyano propargyl radicals

The chemical dynamics of the reaction of ground state carbon atoms, C(3Pj), with vinyl cyanide, C2H3CN(X 1A'), were examined under single collision conditions at collision energies of 29.9 and 43.9 kJ mol(-1) using the crossed molecular beams approach. The experimental studies were combined with electronic structure calculations on the triplet C4H3N potential energy surface (H. F. Su, R. I. Kaiser, A. H. H. Chang, J. Chem. Phys., 2005, 122, 074320). Our investigations suggest that the reaction follows indirect scattering dynamics via addition of the carbon atom to the carbon-carbon double bond of the vinyl cyanide molecule yielding a cyano cyclopropylidene collision complex. The latter undergoes ring opening to form cis/trans triplet cyano allene which fragments predominantly to the 1-cyano propargyl radical via tight exit transition states; the 3-cyano propargyl isomer was inferred to be formed at least a factor of two less; also, no molecular hydrogen elimination channel was observed experimentally. These results are in agreement with the computational studies predicting solely the existence of a carbon versus hydrogen atom exchange pathway and the dominance of the 1-cyano propargyl radical product. The discovery of the cyano propargyl radical in the reaction of atomic carbon with vinyl cyanide under single collision conditions implies that this molecule can be an important reaction intermediate in combustion flames and also in extraterrestrial environments (cold molecular clouds, circumstellar envelopes of carbon stars) which could lead to the formation of cyano benzene (C6H5CN) upon reaction with a propargyl radical.

Stripping dynamics in the reactions of electronically excited carbon atoms, C(1D), with ethylene and propylene—production of propargyl and methylpropargyl radicals

The reactions of electronically excited carbon atoms, C(1D), with ethylene and propylene were studied at three collision energies between 48 and 104 kJmol−1 employing the crossed molecular beam technique. Forward-convolution fitting of our data combined with electronic structure calculations suggests that the reactions proceed via stripping dynamics. Extremely short-lived allene and 1,2-butadiene intermediates decompose via atomic hydrogen emission to yield propargyl and methylpropargyl radicals, respectively. These production routes are of potential importance to form benzene, toluene, and o-/p-xylenes in circumstellar envelopes of carbon stars and combustion flames.

Product Branching Ratios of the C(3P) + C2H3(2A‘) and CH(2Π) + C2H2(1Σg+) Reactions and Photodissociation of H2CC⋮CH(2B1) at 193 and 242 nm: an ab Initio/RRKM Study

The C(3P) + C2H3(2A‘) and CH(2Π) + C2H2 reactions have been studied using ab initio/RRKM calculations to investigate possible formations of C3H2 and C3H isomers in extraterrestrial environments such as circumstellar envelopes of carbon stars and cold molecular clouds, combustion processes, and CVD. Microcanonical rate constants and product branching ratios have been calculated. Product branching ratios for the C(3P) + C2H3(2A‘) are obtained as 78.3−81.8% for the HCCCH(3B) +H products, 6.1−7.3% for c-C3H2(1A1) + H, 4.4−8.1% for H2CCC(1A1) + H, 5.5% for HCCC(2A‘) + H2, and 1.0−2.0% for the CH(2Π) + C2H2 products, depending on the initial concentrations of intermediates c-H2CCCH and H2CC(H)C, both of which can be produced at the initial reaction step without entrance barrier. Thus, the C(3P) + C2H3(2A‘) reaction can be expected to mainly produce C3H2 isomers in extraterrestrial environments. Product branching ratios for the CH(2Π) + C2H2 reaction slightly vary with the initial concentrations of two initial complexes c-C3H3 and CHCHCH, which can be formed from the reactants without barriers and are calculated as 84.5−87.0% for HCCCH(3B) + H, 10.2−12.8% for c-C3H2(1A1) + H, 1.8−1.9% for HCCC(2A‘) + H2, and 0.9% for H2CCC(1A1) + H. The photodissociation of propargyl radical has been also investigated at photon energies of 193 and 242 nm, assuming internal conversion into the ground electronic state before dissociation. Product branching ratios calculated at 193 nm are 86.5% for the HCCCH(3B) + H channel, 3.6% for c-C3H2(1A1) + H, 5.5% for HCCC(2A‘) + H2, 3.5% for H2CCC(1A1) + H, and 0.9% for CH(2Π) + C2H2. These results are in line with experimental measurements (ref 24), which gave 96% and 4% branching ratios for the C3H2 + H and C3H + H2 channels, respectively. Product branching ratios obtained at 242 nm are 90.2% for the HCCCH(3B) + H channel, 5.1% for c-C3H2(1A1) + H, 3.0% for HCCC(2A‘) + H2, 1.6% for H2CCC(1A1) + H, and 0.1% for CH(2Π) + C2H2. Thus, HCCCH(3B) and H are predicted to be the major products, while c-C3H2 and H are expected to play only a minor role.

A combined crossed beam and ab initio investigation on the reaction of carbon species with C4H6 isomers. III. 1,2-butadiene, H2CCCH(CH3) (X 1A′)—a non-Rice–Ramsperger–Kassel–Marcus system?

Crossed molecular beam experiments were conducted to investigate the reaction of ground state carbon atoms, C(3Pj), with 1,2-butadiene, H2CCCH(CH3) (X 1A′), at three collision energies of 20.4 kJ mol−1, 37.9 kJ mol−1, and 48.6 kJ mol−1. Ab initio calculations together with our experimental data reveal that the reaction is initiated by a barrier-less addition of the carbon atom to the π system of the 1,2-butadiene molecule. Dominated by large impact parameters, C(3Pj) attacks preferentially the C2–C3 double bond to form i1 (mechanism 1); to a minor extent, small impact parameters lead to an addition of atomic carbon to the C1–C2 bond yielding i2 (mechanism 2). Both cyclic intermediates i1 and i2 ring open to triplet methylbutatriene complexes i3′ (H2CC*CCH(CH3)) and i3″, (H2CCC*CH(CH3)); C* denotes the attacked carbon atom. i3′ is suggested to decay nonstatistically prior to a complete energy randomization via atomic hydrogen loss forming 1- and 4-methylbutatrienyl CH3CCCCH2 (X 2A″) and HCCCCH(CH3) (X 2A″), respectively. The energy randomization in i3″ is likely to be complete. This isomer decomposes via H atom loss to 3-vinylpropargyl, H2CCCC2H3(X 2A″), as well as 1- and 4-methylbutatrienyl radicals. In high-density environments such as the inner regions of circumstellar envelopes of carbon stars and combustion flames, these linear C5H5 isomers might undergo collision induced isomerization to cyclic structures like the cyclopentadienyl radical. This isomer is strongly believed to be a key intermediate involved in the production of polycyclic aromatic hydrocarbon molecules and soot formation. These characteristics make the reactions of atomic carbon with C4H6 isomers compelling candidates to form C5H5 isomers in the outflow of AGB stars and oxygen-deficient hydrocarbon flames.

A combined crossed beam and ab initio investigation on the reaction of carbon species with C4H6 isomers. II. The dimethylacetylene molecule, H3CCCCH3(X1A1g)

The reaction of ground state carbon atoms, C(3Pj), with dimethylacetylene, H3CCCCH3, was studied at three collision energies between 21.2 and 36.9 kJmol−1 employing the crossed molecular beam approach. Our experiments were combined with ab initio and RRKM calculations. It is found that the reaction is barrierless via a loose, early transition state located at the centrifugal barrier following indirect scattering dynamics through a complex. C(3Pj) attacks the π system of the dimethylacetylene molecule to form a dimethylcyclopropenylidene intermediate either in one step via an addition to C1 and C2 of the acetylenic bond or through an addition to only one carbon atom to give a short-lived cis/trans dimethylpropenediylidene intermediates followed by ring closure. The cyclic intermediate ring opens to a linear dimethylpropargylene radical which rotates almost parallel to the total angular momentum vector J. This complex fragments to atomic hydrogen and a linear 1-methylbutatrienyl radical, H2CCCCCH3(X2A″), via a tight exit transition state located about 18 kJmol−1 above the separated products. The experimentally determined exothermicity of 190±25 kJmol−1 is in strong agreement with our calculated data of 180±10 kJmol−1. The explicit verification of the carbon versus hydrogen exchange pathway together with the first identification of the H2CCCCCH3 radical represents a third pathway to form chain C5H5 radicals in the reactions of C(3Pj) with C4H6 isomers under single collision conditions. Previous experiments of atomic carbon with the 1,3-butadiene isomer verified the formation of 1- and 3-vinylpropargyl radicals, HCCCHC2H3(X2A″), and H2CCCC2H3(X2A″), respectively. In high-density environments such as combustion flames and circumstellar envelopes of carbon stars, these linear isomers can undergo collision-induced ring closure(s) and/or H atom migration(s) which can lead to the cyclopentadienyl radical. The latter is thought to be a crucial reactive intermediate in soot formation and possibly in the production of polycyclic aromatic hydrocarbon molecules in outflow of carbon stars. Likewise, a H atom catalyzed isomerization can interconvert the 3-vinylpropargyl and the 1-methylbutatrienyl radical.

Formation of Core-Mantle Type Grains Consisting of a SiC Core and a Carbon Mantle in Circumstellar Envelopes of Carbon Stars

Formation of Core-Mantle Type Grains Consisting of a SiC Core and a Carbon Mantle in Circumstellar Envelopes of Carbon Stars

Water maser emission toward V788 Cygni - A carbon star

view Abstract Citations (54) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Water Maser Emission toward V788 Cygni, a Carbon Star Nakada, Y. ; Izumiura, H. ; Onaka, T. ; Hashimoto, O. ; Ukita, N. ; Deguchi, S. ; Tanabe, T. Abstract Radio emission lines of H2O, SiO, HCN, and CO have been searched in the circumstellar envelopes of carbon stars which exhibit the 10 μm silicate feature in the IRAS low-resolution spectra. Water maser emission at 22 GHz has been detected in V778 Cyg. No other emission has been detected in the carbon stars BM Gem, V778 Cyg, and EU And. Two competing interpretations for this curious association of the silicate feature and the water maser with the carbon star, the transient stage hypothesis and the binary one, are examined based upon the present observations. Five other carbon stars and two S stars were also observed for comparison. Publication: The Astrophysical Journal Pub Date: December 1987 DOI: 10.1086/185061 Bibcode: 1987ApJ...323L..77N Keywords: Carbon Stars; Stellar Envelopes; Stellar Spectra; Water Masers; Binary Stars; Carbon Monoxide; Cygnus Constellation; Infrared Astronomy Satellite; S Stars; Silicates; Astrophysics; MASERS; STARS: CARBON; STARS: CIRCUMSTELLAR SHELLS; STARS: INDIVIDUAL CONSTELLATION NAME: V778 CYGNI full text sources ADS | data products SIMBAD (8)