A<i>λ</i>3 mm and 1 mm line survey toward the yellow hypergiant IRC +10420

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

doi:10.1051/0004-6361/201527688

Cited by 22 publications

(26 citation statements)

References 39 publications

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“…The SO (1 × 10 −6 ), SiO (5 × 10 −6 ), and CS (1 × 10 −6 ; after correcting the 13 CS abundance by the estimated 12 C/ 13 C ≈ 10) abundances all lie in the range reported for AGB CSEs (Danilovich et al 2016;Schöier et al 2013;Velilla Prieto et al 2017), while the H 2 CO abundance (2 × 10 −6 ; assuming an orthoto-para ratio of 3) is about an order of magnitude higher than in IK Tau (Velilla Prieto et al 2017). CH 3 OH has an estimated abundance of 3 × 10 −6 (assuming an E-to-A ratio of 1), almost two orders of magnitude higher than towards the supergiant IRC+10420 (Quintana-Lacaci et al 2016). However, the large distance between HD 101584 and the EVS (3 × 10 17 cm) combined with a reasonable expansion velocity of the AGB wind (15 km s −1 ) indicate a time scale of ≈6500 yr.…”

Section: Chemistrysupporting

confidence: 50%

First detection of methanol towards a post-AGB object, HD 101584

Olofsson

Vlemmings

Bergman

et al. 2017

A&A

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The circumstellar environments of objects on the asymptotic giant branch and beyond are rich in molecular species. Nevertheless, methanol has never been detected in such an object, and is therefore often taken as a clear signpost for a young stellar object. However, we report the first detection of CH 3 OH in a post-AGB object, HD 101584, using ALMA. Its emission, together with emissions from CO, SiO, SO, CS, and H 2 CO, comes from two extreme velocity spots on either side of the object where a high-velocity outflow appears to interact with the surrounding medium. We have derived molecular abundances, and propose that the detected molecular species are the effect of a post-shock chemistry where circumstellar grains play a role. We further provide evidence that HD 101584 was a low-mass, M-type AGB star.

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Section: Chemistrysupporting

confidence: 50%

First detection of methanol towards a post-AGB object, HD 101584

Olofsson

Vlemmings

Bergman

et al. 2017

A&A

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“…While common in the envelopes of young stars, methanol is very rare around more evolved stars, having been reported to date towards only three other systems, all in a post-MS phase: the binary system HD 101584 in a common envelope phase with an A6Ia primary that terminated as a postasymptotic giant branch (post-AGB) or red supergiant star (Olofsson et al 2017(Olofsson et al , 2019; in the bi-polar nebula around the post-AGB Mira-type variable OH231.8+4.2 (Sánchez Contreras et al 2018); and a low-significance detection at extremely low abundance towards the massive yellow hypergiant IRC+10420 (Quintana-Lacaci et al 2016). The detections in η Car indicate conditions favorable to complex molecule formation at the upper extreme of stellar mass and evolutionary end point, as a candidate progenitor of a core collapse supernova of Type II (should the primary explode in its current phase) or Type Ib/c.…”

Section: Introductionmentioning

confidence: 99%

CO, Water, and Tentative Methanol in η Carinae Approaching Periastron

Morris

Charnley

Corcoran

et al. 2020

ApJL

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In circumstellar gas, the complex organic molecule methanol has been found almost exclusively around young stellar objects, and is thus regarded as a signpost of recent star formation. Here we report the first probable detection of methanol around an evolved high-mass star, in the complex circumstellar environment around the Luminous Blue Variable η Carinae, while using ALMA to investigate molecular cloud conditions traced by CO (2-1) in an orbit phase of the massive binary preceding the 2020 periastron. Favoring methanol over a 13 CS alternative, the emission originates from hot (T gas 700 K) material, ∼2 (0.02 pc) across, centered on the dust-obscured binary in contrast to the CO which traces inner layers of the extended massive equatorial torus, and is accompanied by prominent absorption in a cooler (T gas 110 K) layer of gas. We also report detections of water in Herschel/HIFI observations at 557 GHz and 988 GHz. The methanol abundance is several to 50 times higher than observed towards several lower mass stars, while water abundances are similar to those observed in cool, dense molecular clouds. The very high methanol:water abundance ratio in the core of η Carinae may suggest methanol formation processes similar to Fischer-Tropsch-type catalytic reactions on dust grains. These observations prove that complex molecule formation can occur in the chemically evolved environments around massive stars in the end stages of their evolution, given sufficient gas densities and shielding conditions as may occur in material around massive interacting companions and merger remnants.

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“…The modelling exercises of Wong (2013) found that it was impossible to explain the SiO emission, in particular the radial intensity profiles, with the model of two disconnected gas shells from Castro-Carrizo et al (2007). Indeed, a higher gas density throughout the entire SiO-emitting region is required (Wong 2013;Quintana-Lacaci et al 2016). Therefore, it is speculated that the SiO emission originates from localised clumpy structures, possibly created by shocks, that are not represented by the global mass-loss history as traced by CO emission (Wong 2013, Dinh-V.-Trung et al, in prep.…”

Section: Nh 3 Model Of Irc +10420mentioning

confidence: 99%

“…These O-rich sources towards which Nbearing molecules other than HCN have been detected include OH 231.8+4.2 Sánchez Contreras et al 2015), IRC +10420 (Quintana- Lacaci et al 2013Lacaci et al , 2016, and IK Tau (Velilla Prieto et al 2017). This may suggest that there could be a general enhancement of the production of 14 N from stellar nucleosynthesis (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Circumstellar ammonia in oxygen-rich evolved stars

Wong

Menten

Kamiński

et al. 2018

A&A

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Context. The circumstellar ammonia (NH 3 ) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH 3 abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry. Aims. We would like to characterise the spatial distribution and excitation of NH 3 in the oxygen-rich circumstellar envelopes (CSEs) of four diverse targets: IK Tau, VY CMa, OH 231.8+4.2, and IRC +10420. Methods. We observed NH 3 emission from the ground state in the inversion transitions near 1.3 cm with the Very Large Array (VLA) and submillimetre rotational transitions with the Heterodyne Instrument for the Far-Infrared (HIFI) aboard Herschel Space Observatory from all four targets. For IK Tau and VY CMa, we observed NH 3 rovibrational absorption lines in the ν 2 band near 10.5 µm with the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF). We also attempted to search for the rotational transition within the excited vibrational state ( 2 = 1) near 2 mm with the IRAM 30m Telescope. Non-LTE radiative transfer modelling, including radiative pumping to the vibrational state, was carried out to derive the radial distribution of NH 3 in the CSEs of these targets. Results. We detected NH 3 inversion and rotational emission in all four targets. IK Tau and VY CMa show blueshifted absorption in the rovibrational spectra. We did not detect vibrationally excited rotational transition from IK Tau. Spatially resolved VLA images of IK Tau and IRC +10420 show clumpy emission structures; unresolved images of VY CMa and OH 231.8+4.2 indicate that the spatial-kinematic distribution of NH 3 is similar to that of assorted molecules, such as SO and SO 2 , that exhibit localised and clumpy emission. Our modelling shows that the NH 3 abundance relative to molecular hydrogen is generally of the order of 10 −7 , which is a few times lower than previous estimates that were made without considering radiative pumping and is at least 10 times higher than that in the carbon-rich CSE of IRC +10216. NH 3 in OH 231.8+4.2 and IRC +10420 is found to emit in gas denser than the ambient medium. Incidentally, we also derived a new period of IK Tau from its V-band light curve. Conclusions. NH 3 is again detected in very high abundance in evolved stars, especially the oxygen-rich ones. Its emission mainly arises from localised spatial-kinematic structures that are probably denser than the ambient gas. Circumstellar shocks in the accelerated wind may contribute to the production of NH 3 . Future mid-infrared spectroscopy and radio imaging studies are necessary to constrain the radii and physical conditions of the formation regions of NH 3 .

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Aλ3 mm and 1 mm line survey toward the yellow hypergiant IRC +10420

Cited by 22 publications

References 39 publications

First detection of methanol towards a post-AGB object, HD 101584

First detection of methanol towards a post-AGB object, HD 101584

CO, Water, and Tentative Methanol in η Carinae Approaching Periastron

Circumstellar ammonia in oxygen-rich evolved stars

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