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

Olofsson, H.; Vlemmings, Wouter; Bergman, P.; Humphreys, E. M. L.; Lindqvist, Michael; Maercker, M.; Nyman, L.-Å.; Ramstedt, S.; Tafoya, Daniel

doi:10.1051/0004-6361/201731170

Cited by 17 publications

(26 citation statements)

References 36 publications

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“…In the protoplanetary disk around DG Tau, a T Tauri star, disk-height-averaged column densities of H 2 CO and CH 3 OH were estimated at ∼0.3−4 × 10 14 cm −2 and <0.04−0.7 × 10 14 cm −2 , respectively, with a CH 3 OH/H 2 CO abundance ratio <1 and a H 2 CO ring located beyond the CO snow line (Podio et al 2019). In the circumstellar envelope of the post-asymptotic giant branch (AGB) object HD 101584 (Olofsson et al 2017), H 2 CO, H 13 2 CO, and CH 3 OH were also observed.…”

Section: Introductionmentioning

confidence: 99%

Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices

Basalgète

Dupuy

Féraud

et al. 2021

A&A

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Context. Astrophysical observations show complex organic molecules (COMs) in the gas phase of protoplanetary disks. X-rays emitted from the central young stellar object that irradiate interstellar ices in the disk, followed by the ejection of molecules in the gas phase, are a possible route to explain the abundances observed in the cold regions. This process, known as X-ray photodesorption, needs to be quantified for methanol-containing ices. This Paper I focuses on the case of X-ray photodesorption from pure methanol ices. Aims. We aim at experimentally measuring X-ray photodesorption yields (in molecule desorbed per incident photon, displayed as molecule/photon for more simplicity) of methanol and its photo-products from pure CH3OH ices, and to shed light on the mechanisms responsible for the desorption process. Methods. We irradiated methanol ices at 15 K with X-rays in the 525–570 eV range from the SEXTANTS beam line of the SOLEIL synchrotron facility. The release of species in the gas phase was monitored by quadrupole mass spectrometry, and photodesorption yields were derived. Results. Under our experimental conditions, the CH3OH X-ray photodesorption yield from pure methanol ice is ~10−2 molecule/photon at 564 eV. Photo-products such as CH4, H2CO, H2O, CO2, and CO also desorb at increasing efficiency. X-ray photodesorption of larger COMs, which can be attributed to either ethanol, dimethyl ether, and/or formic acid, is also detected. The physical mechanisms at play are discussed and must likely involve the thermalization of Auger electrons in the ice, thus indicating that its composition plays an important role. Finally, we provide desorption yields applicable to protoplanetary disk environments for astrochemical models. Conclusions. The X-rays are shown to be a potential candidate to explain gas-phase abundances of methanol in disks. However, more relevant desorption yields derived from experiments on mixed ices are mandatory to properly support the role played by X-rays in nonthermal desorption of methanol (see Paper II).

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Section: Introductionmentioning

confidence: 99%

Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices

Basalgète

Dupuy

Féraud

et al. 2021

A&A

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“…This implies a fractional abundance of methanol of the order of X(CH 3 OH)≈10 −8 -10 −7 . This value, while it is expected to have large errorbars, is intermediate to the methanol fractional abundance found in the post-AGB object HD 101584 (~3×10 −6 , Olofsson et al 2017) and in the yellow hypergiant IRC+10420 (~7×10 −8 , Quintana-Lacaci et al 2016).…”

Section: Resultsmentioning

confidence: 58%

“…The detection of CH 3 OH in evolved stars has remained elusive until very recently. Indeed, OH 231.8 is the first CSE of an AGB star in which gas-phase methanol has been identified, after the recent discovery of this molecule with ALMA in the post-AGB object HD 101584 (Olofsson et al 2017). Only one year before, methanol was detected in the yellow hypergiant IRC+10420 (Quintana-Lacaci et al 2016), although this is a different class of object descending from a much more massive star (~50 M ⊙ ) than QX Pup and HD 101584.…”

Section: Resultsmentioning

confidence: 99%

Through the magnifying glass: ALMA acute viewing of the intricate nebular architecture of OH 231.8+4.2

Contreras

Alcolea

Castro-Carrizo

et al. 2018

A&A

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We present continuum and molecular line emission ALMA observations of OH 231.8+4.2, a well studied bipolar nebula around an asymptotic giant branch (AGB) star. The high angular resolution (∼0·″2-0·″3) and sensitivity of our ALMA maps provide the most detailed and accurate description of the overall nebular structure and kinematics of this object to date. We have identified a number of outflow components previously unknown. Species studied in this work include 12CO, 13CO, CS, SO, SO2, QCS, SiO, SiS, H3O+, Na37Cl, and CH3OH. The molecules Na37Cl and CH3OH are first detections in OH 231.8+4.2, with CH3OH being also a first detection in an AGB star. Our ALMA maps bring to light the totally unexpected position of the mass-losing AGB star (QX Pup) relative to the large-scale outflow. QX Pup is enshrouded within a compact (≲60 AU) parcel of dust and gas (clump S) in expansion (Vexp~5-7 km s−1) that is displaced by ∼0·″6 to the south of the dense equatorial region (or waist) where the bipolar lobes join. Our SiO maps disclose a compact bipolar outflow that emerges from QX Pup’s vicinity. This outflow is oriented similarly to the large-scale nebula but the expansion velocities are about ten times lower (Vexp≲35km s−1). We deduce short kinematical ages for the SiO outflow, ranging from ~50-80 yr, in regions within ~150 AU, to ~400-500 yr at the lobe tips (~3500 AU). Adjacent to the SiO outflow, we identify a small-scale hourglass-shaped structure (mini-hourglass) that is probably made of compressed ambient material formed as the SiO outflow penetrates the dense, central regions of the nebula. The lobes and the equatorial waist of the mini-hourglass are both radially expanding with a constant velocity gradient (Vexp ∝ r). The mini-waist is characterized by extremely low velocities, down to ~1 km s−1 at ~150 AU, which tentatively suggest the presence of a stable structure. The spatio-kinematics of the large-scale, high-velocity lobes (HV lobes) and the dense equatorial waist (large waist) known from previous works are now precisely determined, indicating that both were shaped nearly simultaneously about ~800-900 yr ago. We report the discovery of two large (~8″×6″), faint bubble-like structures (fish bowls) surrounding the central parts of the nebula. These are relatively old structures although probably slightly (~100-200 yr) younger than the large waist and the HV lobes. We discuss the series of events that may have resulted in the complex array of nebular components found in OH 231.8+4.2 as well as the properties and locus of the central binary system. The presence of ≲80 yr bipolar ejections indicate that the collimated fast wind engine is still active at the core of this outstanding object.

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“…Another infrared interferometric imaging campaign was performed on HD101584 that has been extensively studied with the Atacama Large Millimeter/submillimeter Array (ALMA). [33][34][35] These observations revealed a bipolar environment as traced by the CO gas (see Fig. 2).…”

Section: Revealing a Complex Environment: Imaging Hd101584mentioning

confidence: 72%

VLTI images of circumbinary disks around evolved stars

Kluska

Claes

Corporaal

et al. 2020

Optical and Infrared Interferometry and Imaging VII

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The new generation of VLTI instruments (GRAVITY, MATISSE) aims to produce routinely interferometric images to uncover the morphological complexity of different objects at high angular resolution. Image reconstruction is, however, not a fully automated process. Here we focus on a specific science case, namely the complex circumbinary environments of a subset of evolved binaries, for which interferometric imaging provides the spatial resolution required to resolve the immediate circumbinary environment. Indeed, many binaries where the main star is in the post-asymptotic giant branch (post-AGB) phase are surrounded by circumbinary disks. Those disks were first inferred from the infrared excess produced by dust. Snapshot interferometric observations in the infrared confirmed disk-like morphology and revealed high spatial complexity of the emission that the use of geometrical models could not recover without being strongly biased. Arguably, the most convincing proof of the disk-like shape of the circumbinary environment came from the first interferometric image of such a system (IRAS08544-4431) using the PIONIER instrument at the VLTI. This image was obtained using the SPARCO image reconstruction approach that enables to subtract a model of a component of the image and reconstruct an image of its environment only. In the case of IRAS08544-4431, the model involved a binary and the image of the remaining signal revealed several unexpected features. Then, a second image revealed a different but also complex circumstellar morphology around HD101584 that was well studied by ALMA. To exploit the VLTI imaging capability to understand these targets, we started a large programme at the VLTI to image post-AGB binary systems using both PIONIER and GRAVITY instruments.

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

Cited by 17 publications

References 36 publications

Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices

Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices

Through the magnifying glass: ALMA acute viewing of the intricate nebular architecture of OH 231.8+4.2

VLTI images of circumbinary disks around evolved stars

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