<i>Spitzer</i>mid-infrared spectroscopic observations of planetary nebulae

Mata, H.; Ramos-Larios, G.; Guerrero, M. A.; Nigoche-Netro, A.; Toalá, J. A.; Fang, Xuan; Rubio, G.; Kemp, S. N.; Navarro, S. G.; Corral, L. J.

doi:10.1093/mnras/stw646

Cited by 22 publications

(25 citation statements)

References 70 publications

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“…Table 4 summarizes near-and mid-IR H 2 lines detected in NGC 6781. As reported by Phillips et al (2011) and Mata et al (2016), pure rotational H 2 lines are detected in the Spitzer/IRS spectra ( Fig. 1, inset).…”

Section: Physical Conditions: Spatial Distributionsupporting

confidence: 82%

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

Otsuka

Ueta

Hoof

et al. 2017

ApJS

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We perform a comprehensive analysis of the planetary nebula (PN) NGC 6781 to investigate the physical conditions of each of its ionized, atomic, and molecular gas and dust components and the object's evolution, based on panchromatic observational data ranging from UV to radio. Empirical nebular elemental abundances, compared with theoretical predictions via nucleosynthesis models of asymptotic giant branch (AGB) stars, indicate that the progenitor is a solar-metallicity, 2.25 − 3.0 M ⊙ initial-mass star. We derive the best-fit distance of 0.46 kpc by fitting the stellar luminosity (as a function of the distance and effective temperature of the central star) with the adopted post-AGB evolutionary tracks. Our excitation energy diagram analysis indicate high excitation temperatures in the photodissociation region (PDR) beyond the ionized part of the nebula, suggesting extra heating by shock interactions between the slow AGB wind and the fast PN wind. Through iterative fitting using the Cloudy code with empirically-derived constraints, we find the best-fit dusty photoionization model of the object that would inclusively reproduce all of the adopted panchromatic observational data. The estimated total gas mass (0.41 M ⊙ ) corresponds to the mass ejected during the last AGB thermal pulse event predicted for a 2.5 M ⊙ initial-mass star. A significant fraction of the total mass (about 70 %) is found to exist in the PDR, demonstrating the critical importance of the PDR in PNe that are generally recognized as the hallmark of ionized/H

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Section: Physical Conditions: Spatial Distributionsupporting

confidence: 82%

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

Otsuka

Ueta

Hoof

et al. 2017

ApJS

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“…This concept seemed to be well-substantiated by observations (e.g., Knapp 1985). Although CO has been identified in numerous PNe (e.g., Huggins et al 1996Huggins et al , 2005, as well as H 2 (e.g., Hora et al 1999;Bernard-Salas & Tielens 2005;Likkel et al 2006;Mata et al 2016), polyatomic molecules were a rarity. Recent measurements, however, are beginning to change this paradigm.…”

Section: Introductionmentioning

confidence: 76%

New Identifications of the CCH Radical in Planetary Nebulae: A Connection to C₆₀?

Schmidt

Ziurys

2017

ApJ

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New detections of CCH have been made toward nine planetary nebulae (PNe), including K4-47, K3-58, K3-17, M3-28, and M4-14. Measurements of the N = 1 → 0 and N = 3 → 2 transitions of this radical near 87 and 262 GHz were carried out using the new 12 m and the Sub-Millimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). The presence of fine and/or hyperfine structure in the spectra aided in the identification. CCH was not observed in two PNe which are sources of C 60 . The planetary nebulae with positive detections represent a wide range of ages and morphologies, and all had previously been observed in HCN and HNC. Column densities for CCH in the PNe, determined from radiative transfer modeling, were N tot (CCH) ∼ 0.2-3.3 × 10 15 cm −2 , corresponding to fractional abundances with respect to H 2 of f ∼ 0.2-47 × 10 −7 . The abundance of CCH was found to not vary significantly with kinematic age across a time span of ∼10,000 years, in contrast to predictions of chemical models. CCH appears to be a fairly common constituent of PNe that are carbon-rich, and its distribution may anti-correlate with that of C 60 . These results suggest that CCH may be a product of C 60 photodestruction, which is known to create C 2 units. The molecule may subsequently survive the PN stage and populate diffuse clouds. The distinct, double-horned line profiles for CCH observed in K3-45 and M3-28 indicate the possible presence of a bipolar flow oriented at least partially toward the line of sight.

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“…This gave access to the H 2 rotational diagram in various sources (PDRs, shocks, YSOs, PNe, SNR, low UV excited clouds, diffuse ISM), as well as its spatial variation in some extended sources (e.g. Neufeld et al, 1998;Draine and Bertoldi, 1999;Cesarsky et al, 1999;Rosenthal et al, 2000;van den Ancker et al, 2000;Lefloch et al, 2003;Neufeld et al, 2009;Maret et al, 2009;Goldsmith et al, 2010;Fleming et al, 2010;Habart et al, 2005bHabart et al, , 2011Hewitt et al, 2009;Rho et al, 2017;Sheffer et al, 2011;Mata et al, 2016). H 2 data have allowed us to better characterize the shocks (e.g., measure the temperature history, and age) associated with outflows from young stars or supernova remnants and the different possible H 2 excitation mechanisms at different evolutionary stages of young stellar objects and planetary nebulae (e.g., Neufeld et al, 1998;Pineau Des Forêts and Flower, 1999;Cesarsky et al, 1999;van den Ancker et al, 2000;Lefloch et al, 2003).…”

Section: H 2 Transitions and Specific Diagnostic Powermentioning

confidence: 99%

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

Wakelam

Bron

Cazaux

et al. 2017

Molecular Astrophysics

231

201

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a b s t r a c tMolecular hydrogen is the most abundant molecule in the universe. It is the first one to form and survive photo-dissociation in tenuous environments. Its formation involves catalytic reactions on the surface of interstellar grains. The micro-physics of the formation process has been investigated intensively in the last 20 years, in parallel of new astrophysical observational and modeling progresses. In the perspectives of the probable revolution brought by the future satellite JWST, this article has been written to present what we think we know about the H 2 formation in a variety of interstellar environments.

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Spitzermid-infrared spectroscopic observations of planetary nebulae

Cited by 22 publications

References 70 publications

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

New Identifications of the CCH Radical in Planetary Nebulae: A Connection to C₆₀?

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

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Spitzermid-infrared spectroscopic observations of planetary nebulae

Cited by 22 publications

References 70 publications

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

New Identifications of the CCH Radical in Planetary Nebulae: A Connection to C60?

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

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New Identifications of the CCH Radical in Planetary Nebulae: A Connection to C₆₀?