<i>Herschel</i>Planetary Nebula Survey (HerPlaNS)

Ueta, Toshiya; Ladjal, D.; Exter, Katrina; Otsuka, Masaaki; Szczerba, R.; Siódmiak, N.; Aleman, Isabel; Hoof, P. A. M. van; Kastner, Joel H.; Montez, Rodolfo; McDonald, Iain; Wittkowski, M.; Ramstedt, S.; Marco, Orsola De; Villaver, E.; Chu, You‐Hua; Sandín, C.; Vlemmings, Wouter; Izumiura, Hideyuki; Sahai, Raghvendra; López, J. A.; Balick, Bruce; Zijlstra, A. A.; Tielens, A. G. G. M.; Rattray, R. E.; Behar, E.; Blackman, Eric G.; Hebden, K.; Hora, J. L.; Murakawa, K.; Nordhaus, Jason; Nordon, R.; Yamamura, I.

doi:10.1051/0004-6361/201322940

Cited by 28 publications

(29 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Models with T * > 80 kK all predict surface brightnesses similar to or higher than observations, while for T * = 50 kK the predicted values are below the lowest observed. Aleman et al (2014) only detected OH + emission from PNe with T * ≥ 100 kK -while our models in this temperature range are consistent with the observed surface brightness, we also predict similar values for T * = 80 kK, whereas observations by Aleman et al (2014) of three high-luminosity PNe with 80 kK ≤ T * < 100 kK did not detect any OH + lines. The reasons for this are discussed in Section 4.5.…”

Section: Resultssupporting

confidence: 88%

“…Our models with T * = 80 kK predict OH + surface brightnesses similar to those with T * = 100 kK. However, of the three PNe listed by Aleman et al (2014) as having T * in the range of 80 − 90 kK, none have OH + detections. All three PNe (NGC 3242, NGC 7009 and NGC 7026) are highly luminous (L * ∼ 2000 − 5000 L⊙; Frew 2008), and have ionized radii of ∼ 0.1 pc, smaller than assumed in our low luminosity models, so the increase in the UV flux, and therefore the photodissociation rates, will be very substantial, accounting for their lack of detectable molecular line emission.…”

Section: Non-detections Of Oh +supporting

confidence: 53%

“…OH + 971 GHz surface brightness versus T * , for models with n H = 10 5 cm −3 , log g = 6.0 and L * = 100 L ⊙ (solid line) and 1000 L ⊙ (dashed line). The dotted horizontal lines show the range of observed values fromEtxaluze et al (2014) andAleman et al (2014).…”

mentioning

confidence: 99%

See 2 more Smart Citations

OH+ emission from cometary knots in planetary nebulae

Priestley

Barlow

2018

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We model the molecular emission from cometary knots in planetary nebulae (PNe) using a combination of photoionization and photodissociation region (PDR) codes, for a range of central star properties and gas densities. Without the inclusion of ionizing extreme ultraviolet (EUV) radiation, our models require central star temperatures T * to be near the upper limit of the range investigated in order to match observed H 2 and OH + surface brightnesses consistent with observations -with the addition of EUV flux, our models reproduce observed OH + surface brightnesses for T * ≥ 100 kK. For T * < 80 kK, the predicted OH + surface brightness is much lower, consistent with the non-detection of this molecule in PNe with such central star temperatures. Our predicted level of H 2 emission is somewhat weaker than commonly observed in PNe, which may be resolved by the inclusion of shock heating or fluorescence due to UV photons. Some of our models also predict ArH + and HeH + rotational line emission above detection thresholds, despite neither molecule having been detected in PNe, although the inclusion of photodissociation by EUV photons, which is neglected by our models, would be expected to reduce their detectability.

show abstract

Section: Resultssupporting

confidence: 88%

Section: Non-detections Of Oh +supporting

confidence: 53%

See 1 more Smart Citation

OH+ emission from cometary knots in planetary nebulae

Priestley

Barlow

2018

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Given the number of molecular lines seen in the spectra, especially with the rare OH + detection (Aleman et al 2014), NGC 6781 has to be treated as a PN rich in neutral gas. Then, it is critical to include the PDR of the nebula for a complete understanding of all of its components (ions, atoms, molecules, and dust).…”

Section: The Molecular Gas Componentmentioning

confidence: 99%

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

Otsuka

Ueta

Hoof

et al. 2017

ApJS

View full text Add to dashboard Cite

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

show abstract

“…more than 30 molecular ions have been detected, however, in the envelopes around low-to-intermediate mass evolved stars detections still remain scarce and limited to HCO + in most cases (see, e.g., Sandford 2011 (Cernicharo et al 1997;Hasegawa & Kwok 2001;Zhang et al 2008, and references therein) and the pre-PN CRL618, where HCO + and N 2 H + are detected (Bujarrabal et al 1988;Pardo et al 2007). Recently, the ion OH + has been detected with Herschel in five PNe (Etxaluze et al 2014;Aleman et al 2014). To our knowledge, in CSEs negatively charged molecular anions have been found to date only in the C-rich AGB star IRC+10216 (e.g., McCarthy et al 2006;Cernicharo et al 2007;Agúndez et al 2010a).…”

Section: Introductionmentioning

confidence: 99%

Molecular ions in the O-rich evolved star OH231.8+4.2: HCO⁺, H¹³CO⁺and first detection of SO⁺, N₂H⁺, and H₃O⁺

Contreras

Velilla-Prieto

Agúndez

et al. 2015

A&A

View full text Add to dashboard Cite

ABSTRACT+ transitions observed are consistent with this ion arising from denser, inner (and presumably warmer) layers of the fossil remnant of the slow AGB CSE at the core of the nebula. From rotational diagram analysis, we deduce excitation temperatures of T ex ∼ 10−20 K for all ions except for H 3 O + , which is most consistent with T ex ≈ 100 K. Although uncertain, the higher excitation temperature suspected for H 3 O + is similar to that recently found for H 2 O and a few other molecules, which selectively trace a previously unidentified, warm nebular component. The column densities of the molecular ions reported here are in the range N tot ≈ [1−8] × 10 13 cm −2 , leading to beam-averaged fractional abundances relative to H 2 of X(HCO + ) ≈ 10 −8 , X(H 13 CO + ) ≈ 2 × 10 −9 , X(SO + ) ≈ 4 × 10 −9 , X(N 2 H + ) ≈ 2 × 10 −9 , and X(H 3 O + ) ≈ 7 × 10 −9 cm −2 . We have performed chemical kinetics models to investigate the formation of these ions in OH 231.8 as the result of standard gas phase reactions initiated by cosmic-ray and UV-photon ionization. The model predicts that HCO + , SO + , and H 3 O + can form with abundances comparable to the observed average values in the external layers of the slow central core (at ∼[3−8] × 10 16 cm); H 3 O + would also form quite abundantly in regions closer to the center (X(H 3 O + ) ∼ 10 −9 at ∼10 16 cm). For N 2 H + , the model abundance is lower than the observed value by more than two orders of magnitude. The model fails to reproduce the abundance enrichment of HCO + , SO + , and N 2 H + in the lobes, which is directly inferred from the broad emission profiles of these ions. Also, in disagreement with the narrow H 3 O + spectra, the model predicts that this ion should form in relatively large, detectable amounts (≈10 −9 ) in the external layers of the slow central core and in the high-velocity lobes. Some of the model-data discrepancies are reduced, but not suppressed, by lowering the water content and enhancing the elemental nitrogen abundance in the envelope. The remarkable chemistry of OH 231.8 probably reflects the molecular regeneration process within its envelope after the passage of fast shocks that accelerated and dissociated molecules in the AGB wind ∼800 yr ago.

show abstract

HerschelPlanetary Nebula Survey (HerPlaNS)

Cited by 28 publications

References 59 publications

OH+ emission from cometary knots in planetary nebulae

OH+ emission from cometary knots in planetary nebulae

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

Molecular ions in the O-rich evolved star OH231.8+4.2: HCO⁺, H¹³CO⁺and first detection of SO⁺, N₂H⁺, and H₃O⁺

Contact Info

Product

Resources

About

HerschelPlanetary Nebula Survey (HerPlaNS)

Cited by 28 publications

References 59 publications

OH+ emission from cometary knots in planetary nebulae

OH+ emission from cometary knots in planetary nebulae

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

Molecular ions in the O-rich evolved star OH231.8+4.2: HCO+, H13CO+and first detection of SO+, N2H+, and H3O+

Contact Info

Product

Resources

About

Molecular ions in the O-rich evolved star OH231.8+4.2: HCO⁺, H¹³CO⁺and first detection of SO⁺, N₂H⁺, and H₃O⁺