Detection of circumstellar nitric oxide

Quintana-Lacaci, G.; Agúndez, M.; Cernicharo, J.; Bujarrabal, V.; Contreras, C. Sánchez; Castro-Carrizo, A.; Alcolea, J.

doi:10.1051/0004-6361/201322728

Cited by 28 publications

(36 citation statements)

References 19 publications

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“…Humphreys et al [17] determined V sys = 58 − 60 km s −1 using a combination of CO and OH bands. We note that the latter is also close to the velocities derived from radio lines of other molecules (see [28] and references therein).…”

Section: Radial Velocities Of Various Features In 2001-2014supporting

confidence: 85%

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

Клочкова

Ченцов

Мирошниченко

et al. 2016

Mon. Not. R. Astron. Soc.

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We present the results of a study of spectral features and the velocity field in the atmosphere and the circumstellar envelope of the hypergiant V1302 Aql, the optical counterpart of the IR source IRC+10420, based on high-resolution spectroscopic observations obtained in 2001-2014. We measured radial velocities of the following types of lines: forbidden and permitted pure emissions, absorption and emission components of lines of ions, pure absorptions (e.g., He i, Si ii), and interstellar components of the Na i D-lines, K i, and DIBs. The heliocentric radial velocity measured for pure absorptions as well as for the forbidden and permitted pure emissions is close to the systemic radial velocity and equal to V r = 63.7±0.3, 65.2±0.3, and 62.0±0.4 km s −1 , respectively. Positions of the absorption components of the lines with inverse P Cyg profiles are stable and indicate the presence of clumps moving toward the star with a velocity of ∼20 km s −1 . The average radial velocity of the DIBs is V r (DIB) = 4.6±0.2 km s −1 . Comparison of the absorption lines observed in [2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014] and those in earlier data shows no noticeable variations. We conclude that the hypergiant reached a phase of slowing down (or termination) of the effective temperature growth and is currently located near the high-temperature boundary of the Yellow Void in the Hertszprung-Russell diagramme.

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Section: Radial Velocities Of Various Features In 2001-2014supporting

confidence: 85%

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

Клочкова

Ченцов

Мирошниченко

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Our model is based on that by Agúndez & Cernicharo (2006) and we have used it recently to study the new N-bearing species detected in OH 231.8 by Velilla Prieto et al (2015). The code has also been employed to model the chemistry in different astrophysical environments, including the prototypical C-rich star IRC+10216 (see, e.g., Agúndez et al 2007Agúndez et al , 2008Agúndez et al , 2010bAgúndez et al , 2012Cernicharo et al 2010Cernicharo et al , 2013, and the O-rich yellow hypergiant IRC+10420 (Quintana-Lacaci et al 2013). The chemical network in our code includes gas-phase reactions, cosmic rays, and photoreactions with interstellar UV photons; it does not incorporate reactions involving dust grains, X-rays or shocks.…”

Section: Chemical Modelmentioning

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

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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.

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“…Several small molecules have been identified in O-rich evolved stars, for instance, CO, H 2 O, HCN, HNC, CN, OH, SiS, SiO, and NO (e.g., Cho & Ukita 1998;Ziurys 2006;Schöier et al 2007;Ziurys et al 2009;Maercker et al 2009;Decin et al 2010b;Quintana-Lacaci et al 2013;Velilla Prieto et al 2015). In addition, some O-bearing inorganic species, e.g., AlO and AlOH, have been identified in the supergiant VY Canis Majoris .…”

Section: Introductionmentioning

confidence: 99%

Chemistry and distribution of daughter species in the circumstellar envelopes of O-rich AGB stars

Millar

Heays

et al. 2016

A&A

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Context. Thanks to the advent of Herschel and ALMA, new high-quality observations of molecules present in the circumstellar envelopes of asymptotic giant branch (AGB) stars are being reported that reveal large differences from the existing chemical models. New molecular data and more comprehensive models of the chemistry in circumstellar envelopes are now available. Aims. The aims are to determine and study the important formation and destruction pathways in the envelopes of O-rich AGB stars and to provide more reliable predictions of abundances, column densities, and radial distributions for potentially detectable species with physical conditions applicable to the envelope surrounding IK Tau. Methods. We use a large gas-phase chemical model of an AGB envelope including the effects of CO and N 2 self-shielding in a spherical geometry and a newly compiled list of inner-circumstellar envelope parent species derived from detailed modeling and observations. We trace the dominant chemistry in the expanding envelope and investigate the chemistry as a probe for the physics of the AGB phase by studying variations of abundances with mass-loss rates and expansion velocities. Results. We find a pattern of daughter molecules forming from the photodissociation products of parent species with contributions from ion-neutral abstraction and dissociative recombination. The chemistry in the outer zones differs from that in traditional PDRs in that photoionization of daughter species plays a significant role. With the proper treatment of self-shielding, the N → N 2 and C + → CO transitions are shifted outward by factors of 7 and 2, respectively, compared with earlier models. An upper limit on the abundance of CH 4 as a parent species of ( 2.5 × 10 −6 with respect to H 2 ) is found for IK Tau, and several potentially observable molecules with relatively simple chemical links to other parent species are determined. The assumed stellar mass-loss rate, in particular, has an impact on the calculated abundances of cations and the peak-abundance radius of both cations and neutrals: as the mass-loss rate increases, the peak abundance of cations generally decreases and the peak-abundance radius of all species moves outwards. The effects of varying the envelope expansion velocity and cosmic-ray ionization rate are not as significant.

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Detection of circumstellar nitric oxide

Cited by 28 publications

References 19 publications

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

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

Chemistry and distribution of daughter species in the circumstellar envelopes of O-rich AGB stars

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Detection of circumstellar nitric oxide

Cited by 28 publications

References 19 publications

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001–2014

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

Chemistry and distribution of daughter species in the circumstellar envelopes of O-rich AGB stars

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